JPS619663A - Magnetic powder dispersed type microcarrier - Google Patents

Abstract

PURPOSE:To improve mold releasability, to enhance fixability, and to form visible images good in reproducibility stably for a long period by incorporating a mold releasing agent in the binder resin of a carrier specified in particle diameter contg. a fine magnetic powder dispersed into it. CONSTITUTION:The mold releasing agent is incorporated in the carrier powder having an average particle diameter of 10-50mum prepared by dispersing the fine magnetic powder into the binder resin. A part of such a carrier small in diameter is fed together with a toner to develop a latent image, but since the carrier contains said releasing agent and has superior mold releasability, it is not fixed to a heating roller at the time of fixing. Accordingly, stains on the reverse side of a transfer paper or winding on the roller, etc., are prevented. The use of the small-diameter carrier can enhance toner concn. and enlarge its allowance, so visible images high in density can be obtained stably. Further, since each bristle of a magnetic brush in the magnetic brush development can be formed properly delicately and softly, the obtained visible image is good in sharpness and gradation and high in reproduciblity.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to a method used for developing an electrostatic latent image or a magnetic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc. The present invention relates to a carrier, and more specifically to a magnetic material-dispersed microcarrier.

[Technology background]

Generally, in electrophotography or electrostatic recording, in order to develop an electrostatic latent image formed on a latent image carrier made of a photoconductive photoreceptor or a dielectric material, toner, which is a colored fine powder, and a carrier are used. Two-component developers are widely used. This two-component developer uses agitation to cause friction between the toner and carrier to charge the toner to a specific polarity, and uses electrostatic attraction with the electrostatic charges that make up the electrostatic latent image to hold the toner as a latent image. Development is achieved by adhering the toner to the body, and it is relatively easy to control triboelectrification of the toner, and it is also possible to provide the developer with sufficiently high fluidity, making it possible to form sharp visible images. It has characteristics. However, with two-component developers, on the other hand, only the toner is consumed as development progresses, so the mixing ratio of toner to carrier (hereinafter referred to as "
"toner concentration". ) has the disadvantage that the amount of toner replenishment must be strictly regulated in order to maintain it within a certain range. In other words, if the toner concentration is too low, sufficient image density cannot be obtained in the development process, and if the toner concentration is too high, the contact between the toner and the carrier will be insufficient, resulting in poor toner triboelectric charging control. However, it is difficult to obtain a high image quality due to the occurrence of fog, etc., and in the end, the toner density must be adjusted within a certain tolerance range from both viewpoints.

By the way, in the conventional two-component developers that have been put to practical use, the average particle size of the toner is approximately.

The carrier is composed of a large number of particles with an average diameter of about 70 to 200 μm. In such a two-component developer, the average particle size of the carrier is considerably larger than the average particle size of the toner, and the ratio of the total surface area of the carrier to the total surface area of the toner is small, so it is difficult to ensure sufficient contact between the two. While it is necessary to lower the total toner density considerably in order to achieve the desired image density, it is necessary to increase the toner density from the viewpoint of image density, which means that the tolerance range is narrow and it is difficult to obtain visible images with stable image quality. There are problems. Furthermore, if the average particle size of the carrier is large, when a suitable magnetic brush development method is adopted as the development method, the ears of the magnetic brush formed on the developer transport carrier for transporting the developer will be rough. Therefore, the resolution tends to be insufficient and the sharpness and gradation of the formed visible image tend to be low.

In order to solve the above-mentioned problems, it is effective to reduce the average particle size of the carrier.
Japanese Patent No. 6134 discloses a small diameter carrier for magnetic brush development formed by dispersing magnetic fine particles in an insulating resin.

However, such small-diameter carriers have a particle size that is not much different from that of toner, and are easily scattered. Because it is difficult to make the toner have large magnetic properties, the holding force exerted by the magnetic sleeve for transporting the developer is small, and as a result, during development, a considerable amount of carrier carries the latent image along with the toner. In some cases, up to 30% of the powder image formed by development may be formed by carrier particles. As a result, such powder images are transferred to later transfer and fixing processes, resulting in various problems.

For example, if a heat roller fixing method is used as the fixing method, which is advantageous in that it has high thermal efficiency and can perform high-speed fixing, the carrier to be fixed will adhere to the heat roller, resulting in a large diameter When using a carrier of However, there is a problem in that even if the toner is of good quality, a visible image of good quality cannot be obtained.

[Purpose of the invention]

The present invention was made against the above-mentioned background, and its purpose is to have excellent mold releasability, achieve good fixing with toner by a hot roller fixing method, and improve reproducibility. An object of the present invention is to provide a magnetic material-dispersed microcarrier that can stably form an excellent visible image over a long period of time.

[Structure of the invention]

The above purpose is to provide particle powder with an average particle size of 10 to 50 μm, in which fine magnetic powder is dispersed in a binder resin,
This is achieved by a magnetic material-dispersed microcarrier which is characterized by containing a mold-releasing substance.

The present invention will be explained in detail below.

In the present invention, fine magnetic powder is dispersed in a binder resin to form carrier particles, and a releasing substance is present inside and/or on the surface of the carrier particles, and if necessary, charge control is performed. The average particle size is 10 to 50μ by containing other additive components such as
A magnetic substance-dispersed microcarrier is constituted by particle powder having a particle size of 15 to 40 m, preferably 15 to 40 m.

Such a carrier can be produced by (a) a method of melt-kneading a binder resin and carrier components such as magnetic fine powder and a mold-releasing substance, followed by pulverization and further classification, and (b) a method of adding a mold-releasing substance to the binder resin. Manufactured using a method such as dispersing and containing a carrier component such as fine magnetic powder to form core particles, applying a solution of a releasing substance to the surface of the core particles by spraying, etc., and drying. can do.

As the binder resin in the present invention, various thermoplastic resins can be used, including addition polymerization type resins such as styrene resin, styrene-acrylic resin, styrene-butadiene resin, and acrylic resin, polyester resin,
Examples include condensation polymerization resins such as polyamide resins, and epoxy resins.

Among these resins, monomers for forming addition polymerization type resins include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2.4- dimethylstyrene, p
-n-butylstyrene, p-tert-phthylstyrene, p-n-hexylstyrene, p-n-octylstyrene 5 p-n-nonylstyrene, p-n-decylstyrene p -n-totecylstyrene, p-methoxy Styrene, p-phenylstyrene, p-chlorostyrene, 3.
Styrenes such as 4-dichlorostyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl chloride, vinylidene chloride,
Vinyl halides such as vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl globionate, vinyl benzoate, and vinyl butyrate; methyl acrylate,
Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, i-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, acrylic acid Phenyl, α-
Methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylate α-methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl acrylate, stearyl methacrylate, phenyl methacrylate, dimethylamine ethyl methacrylate, and diethylaminoethyl methacrylate; acrylics such as acrylonitrile, methacrylonitrile, and acrylamide Acid or methacrylic acid tlj d form: Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl impropenyl ketone; N-vinylpyrrole, N-vinyl N-vinyl compounds such as carbazole, N-vinylindole, and hepinylpyrrolidone; monoolefin monomers such as vinylnaphthalene; diolefin monomers such as propadiene, phtadiene, isoprene, chlorobrene, pentagene, and hexadiene. can be exemplified. These monomers can be used alone or in combination of two or more.

In addition, monomers for forming the condensation polymerization type resin include ethylene glycol, triethylene glycol, 1.
2-propylene glycol, ■, 3-propylene oligolicol, 4-butanediol, neopentyl glycol, ■, 4-butynediol, 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A.

Polyhydric alcohols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A, polyhydric amines such as ethylene diamine, tetramethylene diamine, pentamethylene diamine, piperazine, hexamethylene diamine, and maleic acid, fumaric acid, and mesaconic acid. , citraconic acid, itaconic acid, gutataconic acid,
Phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, cepatic acid,
Examples include polyhydric carboxylic acids such as malonic acid or esters thereof with acid anhydrides or lower alcohols, and dimers of liluic acid.

The magnetic materials constituting the magnetic fine powder in the present invention include substances that are extremely strongly magnetized in the direction of a magnetic field;
For example, metals such as iron, cobalt, nickel, ferrite, magnetite, hemata, etc.
Alloys or compounds containing ferromagnetic elements such as cobalt and nickel, or alloys that do not contain ferromagnetic elements but can become ferromagnetic through appropriate heat treatment;
For example, alloys called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide can be used.

The average particle size of the magnetic fine powder is preferably about 0.05 to 3 μm. The proportion of the magnetic fine powder to be used is 30 to 80% by weight, preferably 50 to 75% by weight based on the carrier.
It is desirable to set it as weight%. - The releasable substance in the present invention is selected from among substances that melt at a temperature lower than the softening point of the binder resin constituting the carrier, have low surface energy, and have good releasability.

Examples of such releasing substances include polyolefins, fatty acid metal salts, fatty acid esters, partially saponified fatty acid esters, higher fatty acids, higher alkyls, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, and silicone. Fes, aliphatic fluorocarbon, fluorine-containing surfactant, etc. can be mentioned. Such mold-releasing substances can be used alone or in combination of two or more.

Examples of the polyolefin include polypropylene,
Resin such as polyethylene or polybutene, JIS wood 2
531-1960 when measured by the ring and ball method, the softening point is 80 to 180°C, preferably 100 to 180°C.
The temperature is 160°C. Examples of the fatty acid metal salts include metal salts of maleic acid and zinc, magnesium, calcium, etc.; metal salts of stearic acid and zinc, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium, etc.; Dibasic lead stearate; oleic acid and zinc, magnesium, iron, co-quart, copper,
Metal salts of lead, calcium, etc.; metal salts of palmitic acid and aluminum, calcium, etc.; lead caprylate; lead caproate; metal salts of linoleic acid and zinc, co-curth, etc.;
Calcium ricinoleate: metal salts of ricylinic acid with zinc, cadmium, etc., and mixtures thereof.

Examples of the fatty acid ester include ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, and ethylene glycol montanate. Examples of the partially saponified fatty acid ester include partially saponified calcium esters of montanic acid.

Examples of the higher fatty acids include dodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, arachidic acid, behenic acid, lignoceric acid, montanic acid, ceracoleic acid, etc., and mixtures thereof. can be mentioned. Examples of the higher alcohol include silyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, aracyl alcohol, and behenyl alcohol. Examples of the paraffin wax include natural paraffin, microwax, synthetic paraffin, and chlorinated hydrocarbons. As the amide wax,
For example, stearic acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide,
Examples include methylene bis stearamide and ethylene bis stearamide. Examples of the polyhydric alcohol ester include glycerin stearate, glycerin lysyllate, glycerin JJ monobehenate, nrubitan monostearate, propylene glycol monostearate, sorbitan triolate, and the like. As the silicon face, for example, methyl silicon face,
Examples include phenyl silicone fest. Examples of the aliphatic fluorocarbon include low polymer compounds such as tetrafluoroethylene and hexafluoropropylene. Further, as the fluorine-containing surfactant, for example, JP-A-53-1
Examples include those described in No. 24428.

The ratio of these mold release substances used is 0.0% to the carrier.
5 to 20% by weight, preferably 1 to 10% by weight;
is desirable. If the proportion of the mold-releasing substance used is less than 0.5% by weight, sufficient mold-releasing properties cannot be obtained;
If it exceeds 0% by weight, the fluidity of the carrier will decrease.

In the present invention, additives such as colorants and charge control agents may be included as necessary.

Such colorants include carbon black, aniline blue (C0f, NIIL50405), calco oil blue (C, I, N [Lazoec Blue 3)
s chrome yellow (c, r, Nl1t4oc+o),
Ultramarine Blue (C31, N[L77103),
DuPont Oil Red (C, I.

N11L26105), quinoline ye o -(-c,
I, N147005), methylene blue chloride (
C, I, N152015), Phthalocyanine Blue (C,1, Na7.4160), Malachite Green Oxale) (C,1, Na42000), Lamp Black (C,1, N177266), Rose Bengal (
C,1,N[L45435), mixtures thereof, and others.

Further, as the charge control agent, for example,
Fettgchw HBN (Fettgchw) having positive triboelectric charging properties as described in Japanese Patent No. 2427
Brz HBN ; C, 1, N[L 2615 (j
) Nigrosine soluble in alcohol
n: C, 1, 50415).

Sudan Chief Shubarut BB (5udan tie
fschwarz138; Solhento Black 3
; C, 1, Na26150).

Brilliant Spirit Schwarz TN (Brilla
nts-pritschwarz'INS Falpen, Faprikken, manufactured by Bahia), Zaponspar 7
X (ZaponschwBrz
I (l G; Falpen, Fapriken, Bahia), Chromosin Spartz ETOO (Chromog
en 5chtvarz Round sword; C, 1, N [LL46
45), Azo Oil Black (R) (Azo-Oi 1
-Black (R) "rsV E f le, -y=
+) Nsha H').

Examples include dyes such as Spin Black TRH (manufactured by Hodogaya Chemical Co., Ltd.) and Bontron 534 (manufactured by Orient Chemical Co., Ltd.) and pigments such as phthalocyanine blue. Further, oxidized carbon black and resins having positive or negative charge control groups can be considered as a type of charge control agent.

Further, in order to improve the compatibility of these charge control agents with the resin component, they can be added in the form of salts formed with higher fatty acids, or a compatibility improver can be added separately.

The toner to be mixed with the carrier of the present invention to form the developer is not particularly limited, and any known toner can be used, but the toner has an average particle size of 20 μm or less, preferably 8 to 12 μm.
The above-mentioned releasing substance is added to the toner for 1
It is preferable that the content is 25% by weight.

The two-component developer composed of the carrier and toner of the present invention can be used in conventional dry developing methods such as the cascade method, bristle brush method, and magnetic brush method, and is particularly suitable for the magnetic brush method. Can be used.

Next, we will discuss a method in which an oscillating electric field is applied to the visual developer layer on the surface of the developer transporting carrier, which is suitable for developing an electrostatic latent image using a two-component developer constituted by the carrier of the present invention. The magnetic brush development method will be described.

The developer transport carrier for supplying the developer to the development space is
A device similar to the conventional one capable of applying a bias voltage can be used, and a structure in which a rotating magnet having a plurality of magnetic poles is provided inside a sleeve on which a developer layer is supported on one surface is particularly preferable. Can be used. In such a developer transport carrier, the rotation of the rotating magnet causes the developer layer carried on the surface of the sleeve to move in an undulating manner, so that new developer is continuously supplied. Furthermore, even if there is some degree of non-uniformity in the thickness of the developer layer on the surface of the sleeve, the above-mentioned wave-like undulations sufficiently cover the effect so that it does not become a problem in practice. It is preferable that the developer transport speed V due to the rotation of the rotating magnet or the rotation of the sleeve is almost the same as or faster than the moving speed of the electrostatic image carrier. Also,
The conveyance direction due to the rotation of the rotating magnet and the rotation of the sleeve is
The same direction is preferred. Image reproducibility is better in the same direction than in the opposite direction. However, it is not limited to these.

Further, it is preferable that the developer layer supported on the developer transport carrier has a uniform thickness.For example, the developer adhering to the developer transport carrier is sufficiently scraped off by a blade that regulates the thickness. It is preferable to form a uniform layer. The gap between the developer transport carrier and the electrostatic image carrier is expressed by the number 1.
0 to 2000 μm is preferable. If the gap 1 between the developer transport carrier and the electrostatic image carrier becomes too narrow by several 10 μm, it will be difficult to form a magnetic brush S that acts uniformly in the developing space, and a sufficient amount of toner particles cannot be supplied to the development space.

It becomes difficult to perform stable development, and on the other hand, if the gap is 2
If it greatly exceeds 000 μm, the counter electrode effect will deteriorate and sufficient image density will not be obtained, and there will also be an edge effect in which more toner adheres to the contours than to the center of the electrostatic charge image. growing.

In addition, it is especially important to set the gap and the thickness of the developer layer so that the ears of the magnetic brush do not come into contact with the surface of the electrostatic image carrier without applying an oscillating electric field, and are as close as possible to the surface of the electrostatic image carrier. Preferable. This is because scratches caused by the rubbing of the magnetic brush on the toner image and fogging can be prevented.

Preferably, the oscillating electric field is created by applying an oscillating bias voltage to the sleeve of the developer transport carrier. As the bias voltage, it is preferable to use a voltage obtained by superimposing a DC voltage, which prevents toner particles from adhering to non-image areas, with an AC voltage, which makes it easier for the toner particles to separate from the carrier particles. However, the present invention is not limited to these methods.

An example of a specific apparatus that can be used to carry out the above-described development process is shown in FIG. In Figure 1, l
1 is a drum-shaped electrostatic image carrier made of a photoreceptor such as Se, which rotates in the direction of the arrow, and an electrostatic image is formed on its surface by a charging exposure device (not shown). 2 is a sleeve made of a non-magnetic material such as aluminum; 3 is a magnet body provided inside the sleeve 2 and having a plurality of N and S magnetic poles around the circumference; the sleeve 2 and the magnet body 3 transport the developer; A carrier is constructed. The sleeve 2 and the magnet body 3 are relatively rotatable, and in the illustrated example, the IJ-sphere 2 is rotated in the direction of the arrow, and the magnet body 3 is fixed. The N and S magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force forms a layer of developer material, ie, a magnetic brush, consisting of brush-like spikes on the surface of the sleeve 2. do. 4 is a regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic brush; 5 is a cleaning blade that removes the magnetic brush that has passed through the developing space A from above the sleeve 2; The surface of the sleeve 2 comes into contact with the developer reservoir in the developer reservoir 6, so that the developer reservoir is supplied, and the developer reservoir 7 stirs the developer reservoir to uniformly distribute the components. This is a stirring screw.

Since the toner particles in the developer reservoir 6 are consumed when development is performed, the toner particles T in the toner hopper 8 are
will be replenished accordingly. Reference numeral 9 denotes a supply roller having a concave portion on its surface for dropping the toner particles T into the developer reservoir. A bias power supply 10 applies a bias voltage to the sleeve 2 via a protective resistor 11. A bias voltage having an oscillating alternating current component is applied by the bias power supply 10 between the grounded base 1a of the electrostatic image carrier 1 and the sleeve 2. This bias voltage is, for example, a superimposed voltage of a DC voltage and an AC voltage.The DC component prevents fogging, and the AC component vibrates the magnetic brush to improve the developing effect. For this DC voltage component, a voltage approximately equal to or higher than the non-direct voltage component, for example, 50 to 600 V, is usually used, and for the AC voltage component, a frequency of 100 Hz to l is used.
0KH7, preferably 1-5 K, Hz Te100v
~l OKV voltage is applied. Note that when the toner particles contain a magnetic material, the DC voltage component may be lower than the non-current potential. If the frequency of the AC voltage component is too low, the effect of vibration will be reduced, and if it is too high, the developer will be unable to follow the vibrations of the electric field, resulting in a decrease in image density and the inability to obtain clear, high-quality images. A trend emerges. In addition, the voltage of the AC voltage component is also related to the frequency, but the higher the voltage, the more the magnetic force will vibrate and the more effective it will be, but if it is too high, it will easily cause fogging, and it will cause problems such as lightning strikes. This is not preferable because dielectric breakdown is likely to occur.

In the apparatus described above, the gap between the sleeve 2 and the electrostatic image carrier 1 is set to be in the range of several tens to 2000 μm, and the electrostatic image on the electrostatic image carrier 1 is developed. When this is done, the magnetic brush formed on the surface of the sleeve 2 becomes
As the magnetic flux density on the surface of the sleeve 2 changes as the sleeve 2 rotates, it moves on the sleeve 2 while vibrating, thereby stably and smoothly passing through the gap with the electrostatic image carrier 1. However, at this time, a uniform developing effect is imparted to the surface of the electrostatic image carrier 1, making it possible to stably develop a high image density.

'Also, for example, if several electrode wires are stretched around the development area between the developer transport carrier and the electrostatic image carrier and a vibrating voltage is applied to them, the magnetic brush will not be vibrated. The developing effect can be improved. In that case as well, a direct current bias voltage may be applied to the developer transport carrier, or oscillating voltages of different frequencies may be applied.

Further, the above-described method can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage that is approximately equal to the receiving potential in the non-image background portion of the electrostatic image carrier.

Furthermore, the above-described method can also be applied when the image to be developed is a magnetic latent image.

〔Effect of the invention〕

Since the carrier of the present invention is dusted with a small diameter, a part of it is used together with the toner to develop the latent image. However, since the carrier contains a releasing substance and has excellent releasing properties, This prevents the powder image from being transferred to the heat roller during fixing, resulting in offset phenomena and
The occurrence of staining on the back side of the transfer paper or wrapping of the transfer paper is suppressed. As a result, the effect of using a small diameter carrier, that is, (a) the toner concentration is high and its tolerance range is wide.
Visible images with high image density can be stably obtained.
(b) In the development process using the magnetic brush development method, the ears of the magnetic brush become appropriately delicate and flexible, making it possible to obtain highly reproducible visible images with good sharpness and gradation. It becomes possible to realize the advantages reliably.

In addition, it is possible to keep the content ratio of the release material that should be contained in the toner relatively low, and as a result, the charge control property of the toner that occurs when a large amount of release material is contained in the toner can be reduced. It is possible to avoid adverse effects such as a decrease in the flow rate or a decrease in fluidity.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited to these.

Note that "parts" represent parts by weight.

<Manufacture of toner> 1) Styrene-n-butyl methacrylate copolymer (monomer composition ratio 70:30) 100 parts Carbon black "#30" (manufactured by Mitsubishi Chemical Corporation) 15 parts Load fi control 5iFIJr Nigrosine Base BXJ (manufactured by Orient Chemical Co., Ltd.) 3-part mold release agent “Viscol 550Pj (manufactured by Sanyo Chemical Industries, Ltd.)
Three parts or more of the substances were mixed in a ball mill, further kneaded with two rolls, and then crushed and classified to obtain a nonmagnetic toner with an average particle size of 12 μm. This will be referred to as "toner a."

2) Tos-b A non-magnetic toner was obtained in the same manner as toner a, except that 10 parts of Viscoel 550PJ was used in toner a. This is referred to as "toner b."

3) Tosu-C Styrene-n-butyl methacrylate copolymer (monomer composition ratio 70:30) 100 parts Carbon black R#30J (manufactured by Mitsubishi Chemical Corporation) 15 parts Charge control agent "Bondron 534J (Orient Chemical Co., Ltd.) 3 parts mold release agent "Viscol 550PJ" 3 parts or more of the material was mixed in a ball mill, further kneaded with two rolls, then crushed and classified to obtain a non-magnetic toner with an average particle size of 12 μm. C”.

4) Tos-d Toner C [A non-magnetic toner was obtained in the same manner as Toner C except that 10 parts of Viscoel 550Pj was used. This is called "toner d".

Examples 1 to 12 Polyester resin [Dialec MB/S Cj (manufactured by Diamond Jamrock Co., Ltd.) 100 parts Magnetite rEpT-1000 (manufactured by Toda Kogyo Co., Ltd.) 185 parts or more of substances and 12 types of release agents shown in Table 1. 10 parts of each of the moldable substances were mixed in a ball mill, kneaded with two rolls, then crushed and classified to obtain 12 types of carriers of the present invention having an average particle size of 28 μm. These carriers are referred to as "carrier 1" to "carrier 12J".

Comparative Example 1 Example 1 to Example 1 described above except that no releasing substance was added.
I got a carrier in the same way as in 2.

This will be referred to as "comparison carrier l."

A total of 14 types of developers were prepared by mixing each of the above carriers 1 to 2 and comparative carrier 1 with toner a or toner b in the combinations shown in Table 1 at a weight ratio of 85:15. With each of these, an electrophotographic copying machine [U-Bi
x 1200J (manufactured by Konishiroku Photo Industry Co., Ltd.) was used for a live copying test. The number of copies until the back side became smudged was investigated, and the fluidity of each developer was also investigated. The results are also listed in Table 1. In addition, the electrophotographic copying machine rU-Bix 120
In the 0J modified machine, the shortest distance between the electrostatic image carrier and the sleeve is 0.7 m, and the distance between the regulating blade for regulating the height of the magnetic brush and the sleeve is 0.5 m.
It is 5M.

Examples 13 to 24 Styrene-methyl methacrylate copolymer (monomer composition ratio 70:30) 100 parts magnetite [EPT-1000J 185 parts Charge control agent [Nigrosine Base EXJ (manufactured by Orient Chemical Co., Ltd.)]
7 parts or more of the substance and 10 parts of each of the 12 types of releasable substances shown in Table 2 are mixed in a ball mill, further kneaded with two rolls, then crushed and classified,
Twelve types of carriers of the present invention having an average particle size of 28 μm were obtained. These carriers are called “Career 13” to “Career 24”
shall be.

Comparative Example 2 A carrier was obtained in the same manner as in Examples 13 to 24 above, except that no releasing substance was added. This will be referred to as "comparison carrier 2."

Each of the above carriers 13 to 24 and comparative carrier 2 was mixed with toner cl or toner d in the combinations shown in Table 2 at a weight ratio of 85:15 to prepare a developer.

The electrophotographic copying machine "U" which adopted the magnetic brush method was developed by
A photocopying test was carried out using a modified Bix 1200J (manufactured by Konishiroku Photo Industry Co., Ltd.), and the image density and stain resistance of the resulting copied images were examined, as well as the fluidity of each developer. The results are also listed in Table 2. In addition, in the modified electrophotographic copying machine rU-Bix 1200J, the shortest distance between the electrostatic image carrier and the sleeve is 0.7u, and the regulating blade and sleeve for regulating the height of the magnetic brush are The distance is 0.55 ms. Furthermore, a selenium photoreceptor is used as the photoreceptor.

From the results in Tables 1 and 2, it is clear that all the developers using the carrier of the present invention have high image density, and no contamination such as heat roller stains occurs even after 20,000 continuous copies. Moreover, the fluidity of the developer was also good. On the other hand, in the comparative developer using the comparative carrier, contamination such as hot roller stains occurred after about 500 to 600 cycles, making it difficult to achieve good fixing. Further, in order to completely improve the stain resistance of the comparative developer, using a toner with a large addition ratio of a releasing substance improved the stain resistance, but the image density and the fluidity of the developer were significantly reduced.

Next, as an electrophotographic copying machine, the previously mentioned rU-Bix
The 1200j modified machine was further modified, (a) the distance between the regulating blade and the sleeve was set to 0.30+u to keep the developer layer and the electrostatic image carrier in a non-contact state, and (b) the electrostatic image carrier and the sleeve were kept in a non-contact state. A DC electric field of 1250 cm and an AC electric field of 800 V, 1.5 KH2 were applied between the
Using a modified 200j machine, a photocopying test was carried out using the above-mentioned developer and a comparative developer, and the image density and stain resistance were determined, and the fluidity of each developer was also investigated. The results are shown in Table 3 and Table 4.

From the results in Tables 3 and 4, it is clear that all the developers using the carrier of the present invention have high image density, and no contamination such as heat roller stains occurs even after 20,000 continuous copies. Moreover, the fluidity of the developer was also good. On the other hand, in the comparative developer using the comparative carrier, contamination such as hot roller stains occurred after about 500 to 600 cycles, making it difficult to achieve good fixing.

Furthermore, in order to improve the stain resistance of the comparative developer, when a toner with a large addition ratio of a releasing substance was used, the stain resistance was improved, but the image density and the fluidity of the developer were significantly lowered.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view schematically showing an example of a developing device that can be used to perform a developing process with a developer using a carrier of the present invention. l... Electrostatic image carrier 2... Sleeve 3...
・Magnet 4...Regulation blade 5...
cleaning blade

Claims (1)

[Claims] 1) A magnetic material-dispersed microcarrier characterized in that it is a particle powder having an average particle size of 10 to 50 μm, in which fine magnetic powder is dispersed in a binder resin, and the material contains a releasing substance.