JPH02109059A - Developer for magnetic brush development - Google Patents

Abstract

PURPOSE:To enhance image quality and durability of a developer by specifying the particle diameters of fine colored particles and the specific area of a fluidity donor and mixing 2 kinds of carriers different in particle diameter and saturation magnetization with the colored particles and the fluidity donor. CONSTITUTION:The developer is a mixture of a toner composed of fine colored particles (A) having an average particle diameter of 3 - 9mum, and as the fluidity donor (B) the fine powder having a surface area of >=50m<2> measured by the BET method, such as silica powder, and carrier particles (C) composed of a mixture of 10 - 50wt.% magnetic particles having an average particle diameter of 25 - 45mum and a saturation magnetization of 140 - 240emu/g, and 50 - 90wt.% magnetic particles having an average particle diameter of 45 - 80mum and a saturation magnetization of 45 - 90emu/g.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a dry developer for use in developing electrostatic images used in electrophotography, electrostatic recording, electrostatic printing, and the like. [Prior Art] Conventionally, US Pat. No. 2,297,89 describes the electrophotographic method.
1 s>, Special Publication No. 1973-23910
As described in Japanese Patent No. 24748, etc., the electrostatic charge is changed in the photoconductive layer by corona discharge, and a light image corresponding to the original is exposed to the photoconductive layer. The latent image is formed by erasing it. Development is carried out by depositing a finely powdered electrostatic substance, so-called toner, on the electrostatic latent image thus obtained. The toner is statically attracted to the latent image depending on the amount of load on the light guide layer, forming a toner image with shading. This toner image is transferred to a supporting surface such as paper or cloth as required, and is permanently fixed to the supporting surface using a suitable fixing step such as heating, pressure, solvent treatment, or overcoating. Furthermore, if it is desired to omit the toner image transfer step, this toner image can also be placed on the photoconductive layer. In developing the electrostatic latent image, the toner is mixed with carrier having relatively large particles and used as an electrophotographic developer. All or phase of both toner and carrier! The contact friction of f is chosen so that the toner has a polarity opposite to that of the photoconductive layer. Also, as a result of the contact friction between the two, the carrier electrostatically attaches the toner to the surface.
As a developer, it is transported through the developing device and also supplies toner to the photoconductive layer. One of the conventionally known developing methods is a magnetic brush developing method. This development method uses toner particles made by dispersing dye and face 4 in a binder resin, and highly magnetically permeable powders (carrier particles) such as reduced iron powder, iron oxide powder, carbonyl iron powder, ferrite, and sendust alloy. The mixed dry developer is moved by a magnet, and by the action of the magnetic field, it forms a brush on the surface of the 81 Z5. When this magnetic brush rubs the surface holding the electrostatic latent image, the toner is absorbed by the attraction of the electrostatic latent image. The static latent image is attracted by the magnetic brush and the latent image is visualized. Conventionally, the developer used in the &i magnetic brush development method is an insulating toner with a particle size of about 5 to 10 liters, and a toner with a particle size of 100 to 2
It is constituted by mixing with a carrier consisting of iron powder of about 0.00 μm. However, in the development method using this type of developer, stable development cannot be expected unless the mixing ratio of toner and carrier is kept constant at all times.Moreover, the tolerance range for the mixing ratio is narrow, so the mixing ratio must be kept constant. Measures to keep it constant:'; IX! i must,
Furthermore, images developed by the magnetic brush method using this type of developer are difficult to differentiate in image fi and density regardless of the strength of electrostatic charge, making it impossible to obtain a JII image of an original with rich gradations, and the reproducibility of fine lines is poor. However, it is not something we should be satisfied with. In addition, since the magnetic properties of the iron powder carrier are large, developers containing iron powder carriers may form hard magnetic brushes, which have the disadvantage of causing white lines in solid black areas (white lines in solid black areas). . Furthermore, developers using iron powder carriers have a heavy specific gravity and strong magnetic properties, so the toner particles collide strongly with the carrier particles and stick to them, contaminating the carrier particles and adversely affecting the development characteristics.
It also has the disadvantage of requiring a large amount of torque to drive the magnetic brush. In recent years, it has been proposed to use ferrite as a carrier for magnetic brush development. Since the magnetic properties of Ferrai i carrier are not greater than those of iron powder, solid black lines do not occur due to hard plans, and the durability of the developer is also improved.
Another advantage is that large torque is not required to drive the magnetic brush. However, even when a ferrite carrier is used in the magnetic brush development method, a developer that exhibits sufficiently excellent developability in both gradation and fine line reproducibility has not been obtained. - When the particle size of the toner in the crotch is small (less than 9 squares), the gradation property and 7a line reproducibility are excellent. However, when the particle size of the toner is reduced, the ratio table +hi Jt"t of the toner increases, so it is necessary to reduce the mixing ratio of carrier and toner, and as a result, the degree of C per image becomes low. However, reducing the particle size of the toner deteriorates the fluidity of the toner, making it difficult to mix the toner with the carrier sufficiently, which tends to cause burrs and toner scattering.Therefore, these shortcomings are improved. As a means for achieving this, there is a method of using small particle size iron powder or ferrite as a carrier and further adding a fluid external agent to the small particle size toner. Reproducibility, solid image density, local color, etc. are relatively small, but,
When a small particle size iron powder carrier is used, there are problems such as solid white lines on black areas, carrier contamination by toner, and the need for a large torque to drive the magnetic brush. When used, since the magnetic properties of the carrier are small, the carrier adheres to the photoconductive layer and is transferred onto the surface of a support such as paper, causing deterioration of image quality. [5F, Problems that Ming attempts to solve] Undeveloped [JJ provides a developer for magnetic brush development that solves the above-mentioned drawbacks. That is, the present invention provides a dry type developer that provides high-quality images with excellent line images, solid black images, gradation reproducibility, resolution, etc. Another feature of IJ that has not yet been developed is to provide a dry type developer that can always produce good and high-quality images even if the toner IH level fluctuates. Another object of the present invention is to provide a dry developer that can withstand repeated use without deterioration of performance. Another object of the present invention is to provide a dry developer which has excellent conveyance properties and toner supply efficiency and which can be applied to a wide range of copying equipment from low-speed machines to high-speed machines. [Means and effects for solving the problems] The present invention provides a developer prepared by mixing a toner consisting of colored fine particles and a fluidity improver with carrier particles, wherein the average particle size of each colored fine particle is 3 to 9 μm. The fluidity imparting agent is an ultrafine powder with a specific surface area of 50 rg' and 1 g LI as determined by the BET method, and the carrier particles are magnetic with an average particle size of 25 to 45 mm and a saturation magnetization of 140 to 240 emu/g. A developer for magnetic brush development comprising a mixture of 10 to 50% by weight of particles A and 50 to 90% by weight of magnetic particles B having an average particle size of 45 to 80 l and a saturation magnetization of 45 to 90 emu/g. . The particle size of the colored fine particles used in the present invention is 3 to 91 in volume average particle size, and coarse powder with a particle size of 20.2 pm or more is

[1] is preferably 1.0 $ or less. Since the toner particle size is fine, there is very little static! The toner adheres to the image faithfully, and there is little disturbance in the toner adhesion at the edges of the latent image.As a result, an image with high resolution and good color 1 developability can be obtained. In particular, photographic images often have halftone areas, which are collections of minute latent images, and are more layered.
The effect of the toner particle size appears, resulting in a good f-image. However, on the other hand, since the toner particle size is small, the fluidity of the toner deteriorates, and the 8-coupling between the carrier and the toner is not carried out effectively, causing capri and scattering. Therefore, in the present invention, a fluidity improver is added to the colored fine particles R to improve the fluidity of the toner to I-4. The finer the particle size of the fluidized external agent used in the present invention, the better, and the specific surface area measured by the BET method should be at least 50 ts2/g, preferably at least 80 ts2/g. Examples of such fluidity improvers include, but are not necessarily limited to, those listed in 1- below. For example, silicon oxide, K, aluminum oxide, titanium oxide, zinc oxide, zirconium oxide, carbon black, zinc stearate, calcium stearate, Teflon,
Boria vinylidene chloride, 4j, carrion, white (
;, basic magnesium carbonate, precipitated magnesium carbonate,
Other whole tfl powders can be used. Among them, silicon oxide, titanium oxide, and aluminum oxide zirconium dioxide can be easily produced with a suitable particle size by a one-gas phase method, and are colorless or white, so when used in color toners, they have no negative effect on color. It is more preferable. Furthermore, two or more of these fluidity imparting agents may be added to the nit toner. Application 1- of these fluidizing agents is toner ri I+
), the effect of the present invention is exhibited when the amount is 0.0 to 10% to 1%, and particularly preferably when 0.03 to 5% is added, excellent fluidity and charging stability of the toner can be obtained. show. Furthermore, in the configuration of unreleased II, in addition to l・ner as described in -h, there are 11 magnetic particles A with an average grain size of 25 to 45 μ and a saturation magnetization of 140 to 240 emu/g, and t
:1 diameter is 45~80 hiro and its saturation magnetization is 45~8
Carrier particles containing 62 pieces of magnetic particles E-B of 0 ermu/g are used. Since the magnetic particles 't'-A used in the present invention have a small particle size, they can increase the specific surface area of two carriers, and even if the toner particle size becomes small, the toner and carrier can efficiently maintain a contact zone of centric force < Of ability. becomes. Therefore, fogging and toner scattering do not occur even if the toner concentration in the developer varies slightly, and high image density can be achieved because the carrier retains toner (it is possible to increase the number of crossroads). Although magnetic particle A has a small particle size, it has a large saturation magnetization, so it is difficult to cause carrier adhesion. However, since magnetic particle A has a large saturation magnetization, if it exceeds 50% of the total gear, it will cause solid black parts. Carrier contamination by white lines and toner is likely to occur, and furthermore, a large torque is required to drive the magnetic brush.On the other hand, magnetic particles B used by being mixed with magnetic particles are
It is preferable that the particle size is larger and the IL saturation magnetization is smaller than that of magnetic particle A. By mixing magnetic particle B with magnetic particle A, problems such as solid black white lines and carrier contamination caused by toner can be solved. is improved. In addition, the specific surface area of this mixed carrier is considerably larger than that of conventional carriers, so even if the toner has a small particle size, it can be efficiently charged by contact with the carrier.There is no fogging or toner scattering, and there is no fogging or toner scattering. Providing high-quality images with excellent density etc. 5
6゜The materials used for magnetic particles -A and H are 5.From the respective magnetic property values, magnetic particles A are iron powder, magnetic particles /-B
Although ferrite powder is most preferred, it is not necessarily limited to this. Furthermore, A: The mixed carrier used in the invention may be coated with a resinous material in order to control toner charging, etc. 1-The coating material on the surface of the magnetic particles varies depending on the toner material. For example, as the resin for the positive band, aminoacrylate resin, acrylic resin, or a combination of these resins and styrene resin may be used. Preferred examples of negatively charged resins include silicone resins, polyester resins, polytetrafluoroethylene polymers, monochlorotrifluoroethylene polymers, etc. Polyvinylidene fluoride, etc.
It is located on the negative side of the HF electric series and is preferred, but not necessarily reduced to this. - On the other hand, as the binder resin of the toner used in the present invention, styrene and its substituted products such as polystyrene, polyp-chlorostyrene, and polyvinyltoluene are used. ti ton combination; styrene-P-chlorostyrene copolymer, styrene-
Propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-
Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , styrene-butyl methacrylate copolymer, styrene-acrylic-aminoacrylic copolymer, styrene-aminoacrylic copolymer, styrene-alpha chloromethacrylate Medidere J (tall combination, styrene-acrylonitrile copolymer ('11) , styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether J (ffc
styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene 8m polymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, etc. Styrenic copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyvinyl a
Pyrene, polyester, polyurethane, polyamide, epoxy resin 2 polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin. Aromatic petroleum resin, chlorinated paraffin, paraffin wax,
Can be used alone or in combination. In toners, any suitable pigment or dye can be used as a 4 color 6+1. For example, there are known facial cleansing agents such as carbon black, iron black, phthalocyanine blue, Shin-♂t, quinahydrone, and benzidine yellow. In addition, as a charge control agent, amine compounds, quaternary ammonium compounds, and organic dyes, especially salts, salts, dimethyl-hexadecylammonium chloride, decyl-trimethylammonium chloride, nigrosine base, etc. , nigrosine and dolochloride, Sakuranino γ and crystal/hayleft may also be added. After thorough kneading, mechanical pulverization and classification may be used, or a method of dispersing a material such as magnetic powder in a binder solution and then spray-drying it.
Alternatively, various methods can be applied, such as a polymerized toner manufacturing method in which a toner is obtained by mixing a predetermined material with the J monomer constituting the binder resin and then polymerizing the emulsified suspension. [Examples] The present invention will be specifically explained below using Examples, but these are not intended to limit the present invention in any way. In the present invention, the mM reproducibility was measured by the following method. In other words, an image of an original document with thin lines exactly 100 μm wide, copied under appropriate copying conditions, was used as a measurement sample, and as a measurement device,
From a monitor image enlarged using the Rousev 2F 450 particle anatizer. The line width is measured using the indicator.
Since the fine line image of the toner has unevenness in the width direction, the line width measurement position is set at the uniform line width of the unevenness. From this, the value (%) of fine line reproducibility is calculated using the following formula. , fP: In the invention, the resolution was measured by the following method. In other words, it is a pattern consisting of five thin lines with equal line width and spacing, and 2.8.3.2
．． 3.6.4.0.4.5.5.0.5.8.6.3.
Create an original image that appears to have 7.1 or 8.0 lines. This i 0! f! Observe with a magnifying glass an image obtained by copying an original manuscript with similar line images under appropriate copying conditions, and calculate the resolution value by the number of images (lines/ms) in which iB lines 1111 are clearly separated. do. The larger this number, the higher the resolution. In addition, the number of parts in the formulation of υ is all 1 part. Example 1 The above mixture was heated and kneaded in a roll mill. After cooling it, it was coarsely crushed with a Kafter mill, finely pulverized with an ultra-IF jet mill, and then divided into particles of about 2 to 15 μm with an air classifier.
Nine colored particles with a body average diameter of 7.5 μm were obtained. 100 parts of this particle has a ground surface area of 2508 by the BET method.
A toner was prepared by externally adding 0.8 parts of 27 g of fine silica powder. On the other hand, were mixed respectively to obtain a mixed carrier. The mixed carrier thus formed and the toner were mixed into 9
They were mixed at an it ratio of 0:10 to form a developer. When this developer was used for copying using a commercially available MP-COLOR-D (Canon copier), as shown in Table 1, an image with excellent gradation, excellent image density, fine line reproducibility, and resolution was obtained. Also, even after 10,000 sheets were continuously copied, the image remained as good as the initial one. Comparative Example 1 As a fluidity imparting agent, the specific surface area measured by the BET method was 3.
0rs! The same procedure as in Example 1 was carried out except that 7 g of silica fine powder was used, and the fluidity of the toner was as follows.
, it was difficult to mix well with the carrier, resulting in fogging and toner scattering in images. Comparative Example 2 The average particle size of the iV color particles prepared in Example 1 was 13
．． The same procedure as in Example 1 was carried out except that the 8μ layer was used, and although there was no fog and the image density was high, the III line reproducibility and resolution and 1 gradation were not very good tlf. Using Example 2, the average particle size of potted plants was 6.2 in the same manner as in Example 1.
A red fine powder of μ-yellow was obtained. ARyCh fine powder having a specific surface area of 300 m2/g by BET method was added to the above fine powder as a fluidity imparting agent.
1.0 part was added externally to prepare a toner. − force and were mixed respectively to obtain a mixed carrier. The mixed carrier and toner thus formed were mixed together for 32 hours.
The mixture was mixed at a weight ratio of 2.8 to 28 to form a developer. When this developer was used in the same manner as in Example 1, good results were obtained as in Example 1, as shown in Table 1. Comparative Example 3 When the same procedure as in Example 2 was carried out except that a mixed carrier of the following was used as the carrier, fogging occurred. Comparative Example 4 The same procedure as in Example 2 was carried out except that a mixed carrier of the following was used as the carrier. However, carrier adhesion occurred in both the image area and the non-image area, making it unsuitable for practical use. Actual & Example 3 To the red particles prepared in Example 2, as a fluidity imparting agent,
TlO2 with a specific surface area of 90 m2/g by BET method
Example 2 was carried out in the same manner as in Example 2, except that 1.0 part of fine powder was externally added to form a toner, and the same good results as in Example 2 were obtained. Example 4 The volume average particle diameter of the blue particles prepared in Example 1 was 5.1
gm, and 100 parts of the particles were mixed with surface hydrophobized silica fine powder having a specific surface area of 310 m2/H by the BET method.
5 parts were added externally to form a toner. On the other hand, were mixed respectively to obtain a mixed carrier. The mixed carrier and toner thus formed were mixed at 90:
They were mixed at a deuterium ratio of 10 to form a developer. When this developer was used in the same manner as in Example 1, the same good results as in Example 1 were obtained. (The following is a blank space) Effects of Invention C As described above, Mokubun's developer exhibits excellent effects as described in F. ■1] Fine line + IrIr development A developer with excellent image resolution tonality and image density (2) Always good and high quality IrIr even when toner density fluctuates
IIIl image 1. L3r is a developer that can be used repeatedly without causing performance deterioration. Applicant: Can Co., Ltd.

Claims (1)

[Claims] (1) A toner comprising colored fine particles and a fluidity imparting agent;
A developer formed by mixing carrier particles, in which the colored fine particles have an average particle size of 3 to 9μ, and the fluidity imparting agent is BE.
Magnetic particles A1 are ultrafine powders with a specific surface area of 50 m^2/g or more by T method, carrier particles have an average particle diameter of 25 to 45 μ, and a saturation magnetization of 140 to 240 emu/g.
Magnetic particles B50-9 with an average particle size of 45-80 μ and a saturation magnetization of 45-90 emu/g.
A developer for magnetic brush development characterized by comprising 0% by weight.