JPS615255A - Image forming method - Google Patents

Abstract

PURPOSE:To eliminate fogging by forming a developed image layer of a two- component type developer consisting of a toner and carrier having a specific compsn. on a developer carrying body and supplying the developer layer into a developing space where an oscillating electric field is generated. CONSTITUTION:The space between a sleeve 2 and the drum-shaped electrostatic charge image carrying body 1 consisting of a photosensitive body made of Se, etc. is set in a several 10-2,000mum range. The magnetic flux density on the surface of the magnetic brush formed on the surface of the sleeve 2 changes according to the rotation of the sleeve 2 when the electrostatic charge image on the body 1 is developed. The magnetic brush is consequently moved under oscillation on the sleeve 2, by which the brush is smoothly passed through the space between the sleeve 2 and the body 1. The uniform developing effect is provided to the surface of the body 1 during this time and the stable development of the high image density is thus made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a process of developing a latent image formed by electrophotography, silent recording method, electrostatic printing method, etc. using a two-component developer. This relates to an image/forming method including.

[Prior art]

At present, methods using electrostatic latent images or magnetic latent images, such as electrophotography, are widely used to form visible images from image information. For example, according to an example of electrophotography, a static charge formed on a static image support made of a photoconductive photoreceptor through a charging process and an exposure process is transferred to a developer consisting of electroscopically colored particles called toner. After development, the toner particles are usually transferred and fixed to a transfer material to obtain a visible image.

The developer used to develop such an electrostatic latent image or a magnetic latent image includes a so-called two-component developer consisting of a mixture of toner and a carrier, and a magnetic toner containing a magnetic substance. In systems using a so-called one-component developer, which is used alone without being mixed with a carrier, or a two-component developer, when the toner and the powder are mechanically stirred, the toner is triboelectrically charged. By selecting the characteristics of the carrier, stirring conditions, etc., it is possible to control the toner's charge polarity and charge amount to a degree similar to that of a priest.
In this respect, single-component developers are also superior.

Development methods using such a two-component developer include a magnetic brush method and a custard method, among which the magnetic brush method is preferably used. In this method, a developer layer consisting of brush-like spikes is formed by magnetic force on the surface of the latent image carrier, and this developer layer is rubbed against the surface of the latent image carrier so that all the toner particles adhere to the latent image. Melt.

Conventionally, the two-component developer used in such a magnetic brush method is generally composed of toner particles with an average particle size of about 10-odd μm and magnetic carrier particles with an average particle size of about 70 to 200 μm. In addition, since only the toner is consumed in development using such a two-component developer,
There is a problem in that the toner concentration in the developer changes and the image quality deteriorates, so it is necessary to replenish the toner in the developer and control the toner concentration to be within a certain allowable range.

However, in the above-mentioned two-component developer containing a carrier with a larger diameter than the toner, the allowable range of toner concentration is small, and very advanced technology is required to control the toner concentration. Therefore, there is a problem that the device for controlling the toner concentration is expensive.Moreover, since the diameter of the carrier is large, the brush-like bristles of the developer are inevitably rough. Therefore, the development of the latent image becomes uneven and has poor reproducibility, which poses a problem in that it is difficult to obtain a high-quality image.

For this reason, a small-diameter carrier was developed in which fine magnetic particles were dispersed in a binder resin (Japanese Patent Laid-Open No. 54-66134). According to a two-component developer using such a carrier, the surface area of the entire carrier particles is significantly increased compared to the same amount of large-diameter carrier, which increases the chances of frictional contact between the toner particles and the carrier particles. The smaller the variation in image quality caused by changes in toner density, the wider the allowable range of toner #, making it easier to control toner density. -2-'- However, in a developer containing such a small-diameter carrier, if the charge control substance contained in the toner material, for example, the binder resin of the toner, adheres to the surface of the carrier particles, the triboelectric charging ability of the carrier may be affected. This makes it impossible to impart the desired electrification charge to the toner, making it difficult to use the carrier repeatedly over a long period of time. It is difficult for the particles to separate from the carrier particles.9 As a result, fogging is likely to occur, trailing phenomenon occurs, image density is reduced, and image clarity is low.9 As a result, it is necessary to reduce the carrier diameter. The problem is that it is not possible to fully reap the benefits of doing so.

[Purpose of the invention]

The purpose of this invention is to produce high-density and clear images without fogging by using a two-component developer containing a /J\ diameter carrier. An object of the present invention is to provide an image forming method that can stably form images for a long period of time.

[Structure of the invention]

The above purpose is to form a developer layer of a two-component developer consisting of toner and carrier on a developer transport carrier, and to supply this developer # to a development space that generates an oscillating electric field to carry a latent image. In an image forming method including a developing step for developing a latent image on a body, the binder is made of particles having an average particle diameter of 10 to 50 μm, in which fine magnetic powder is dispersed in the carrier-binder resin. This is achieved by an image forming method characterized in that the resin is a polymer obtained from a fluorine-containing vinyl monomer represented by the following general formula (1) (where R is represents a hydrogen atom or a methyl group; X represents an oxygen atom, a COO group, or a CO group; and R and f represent a fluoroalkyl group.] The present invention will be described in detail below.

In the present invention, a developer transport carrier is disposed opposite to a latent image carrier carrying a latent image with a certain space in which development is performed, that is, a development space, and within this developer transport carrier, for example, developer is held. A developer Iji is produced by arranging a magnet and using the magnetic force of the magnet to cause a two-component developer containing a special carrier (details of which will be described later) to stand up like a brush on the surface of a developer transport carrier. , and the developer layer is in a state where it is not in contact with the latent image carrier, that is, the height of the developer spike is lower than the shortest distance between the latent image carrier and the developer transport carrier in the development space. The particles are supplied to the developing space in a small state, and an oscillating electric field is applied to the developing space, and this oscillating electric field forms developer S (the particles are vibrated and dispersed to form a latent image carrier and a developer transport carrier). This causes the toner particles to adhere to the latent image carried on the latent image carrier, thereby performing development and forming a toner image.

Next, the toner image is transferred to a transfer material such as paper, and the transferred image is fixed in a fixing device by, for example, a contact heat fixing method using a heating roller, thereby forming a visible image.

Next, the carrier that constitutes the entire two-component developer used in the method of the present invention will be explained.

The carrier used in the method of the present invention is a polymer obtained by polymerizing a fluorine-containing vinyl monomer represented by the general formula (1) (hereinafter also simply referred to as a "fluorine-containing vinyl monomer") or A polymer obtained by copolymerizing a fluorine-containing vinyl monomer and other copolymerizable polymerizable monomers used as necessary is used as a binder resin for the carrier, and a magnetic substance is contained in this binder resin. It is a particulate powder with an average particle size of 10 to 50 μm, which is composed of dispersed fine powder.

Structurally, the fluorine-containing vinyl monomer is preferably one in which seven atoms are bonded via two or more atoms to the carbon atoms in the main chain, more preferably three or more atoms. are connected via. Examples of such monomers include those represented by the following general formulas (2) to (5). 0 General formula (2) % Formula % General formula (3).

OH2g=0 0-0-OH20FgOF2-0-R.

pith General formula (4) %formula% General formula (6) GH2 ratio CH 0+CH2-CH2-05R3 General formula (7) %formula% General formula (8) CH2-CH o-ca2cy2cy2-on2.

General formula (9) CF2=CH o-cx1x2x3 General formula (LL) cn2-OH CF2-R2 General formula (b) CH22OH C; F2CH2-0+CH2-CH2-0+-R3 general formula) CF2CH -Q Summer CH2 -0+CH2-GHr-0-)CH3 general formula exposure 4
) CH2-OH ■ 0 days 0 CH2CH2CH2-o- (cn2-C12-0 preferred also in general formula) CH2-CH -Q CH2CH2-o-cn2cy2 CF2-0-112
However, in the above general formula, 1 represents a hydrogen atom or a methyl group, and R2 has 1 to 2 carbon atoms, preferably 2 to 2 carbon atoms.
12, particularly preferably 2 to 8 fluorotetraalkyl groups? R3 represents an alkyl group of carbon 82 to B in which more than half of the hydrogen atoms are substituted with fluorine atoms, and
1, X2, and
m is oll, any of 2.3 *a washi, n f41 or 2? ! -Represent.

Among the monomers represented by the above general formulas (2) to (2), preferred are those represented by general formulas (2) to (5).

Specific examples of the fluorine-containing vinyl monomer include the following.

Exemplary compound (M-1) CFCF3CH2OC0CH=CH2(
2) F5CH20COC(CHIs)<F2(pa
-3) CF5 and F2 have HH2OC0CH=CH2(-
4) CF3CF2CH20GOC: (CH5)-CF
2(M-5) CF3(CF2)2 to H2O00 to H<
F2(M-6) CP, (CF2)2GH20r;0
C(CH5)”0M2(M-7) 015(C;F2
), cH2ococHhiraGH2 (M-8) 0F3
(CF2), 0R20COC(CH,)<Ii□(M
-9) cp5(cp2)4aH2ococn-CH2
(M-10) CF5(OF2)40H2000C(O
H,)=CH2(M-11) cp3(Cr2)6c
H20coca=cn2(M-12) 0Fs(CF
2), 5CH20COCt(CH5)-CH2(M-
13) GF5(CF2)6aH2ococ
n-cn2 (M-54) cp, (CF2) 8
aH2ococ(cn,)se-OH2(M-15) c
p, gcp2cr2CH2ococa-CH2(hl-
16) F2C to CF30; F2CH20(:QC
(CH3)"-CH2(M-+7) CF310F2
0CF'2CQGH20COCR-CH2(M-18
) CF50F200P 20F 20H20COC (
CH3) Engineering CH2 (M-19) cF'3 (CF2)
2 oar2cp2 an2ococH=cu2(M-
X)) CF5(012)200F2t, F2CF20
C, OG(CH3)-CH2(M-21) CP, (
CF2), QCF2(:F2CH2F2CH2OC0
CII=CH2(0F3(cp2)50CF2CF2C
I+2000C(CJ)=cx(2(M-25)C;
F, H2OCl20H20GOCI God CH2 (M-2
6) CF, G1-120GH2GH20COC(CH
y, )=CH7(M −27) GF 2 HCF20
CH2CH2000CH-CH2(M-28) cp
2ncp2ocH2CH20GOC(C14t, )-
CH2(M-29) OF2HCF2(OC
I'I 20H2) 20COCR=CH2(M -3
0) OF 2H to F2 (0 to I(20H2) 20
CO (CH5) = cn2 (M-31) CP
f; 120F 2 to H2OCH2C; F2OC0CH heavy GH2 (M -32) CF3CF2 CF2 CH2
0CH2CH20CO (CH5)=(iH2(M −
33) Ck' 2H to F20 CH2CH20CH=
CH2 (M-34) H2θGH2CH to CF5CF2
20C; H-GH2 (M --35) CF2 H to F
20CI'12 to J (20 to i(2CH2-QC:H
=GH2 The binder resin of the carrier used in the method of the present invention is, for example, a polymer obtained by polymerizing the same type or multiple types of the fluorine-containing vinyl monomers, or the fluorine-containing vinyl monomers. A polymer obtained by copolymerizing the polymerizable monomer and another copolymerizable monomer may be used.

Examples of polymerizable monomers that can be copolymerized with the heptad vinyl monomer include the following.

Namely, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, acrylic fQn
-Butyl, acrylic dispersion butyl, tert acrylic acid
-butyl, neopentyl acrylate, pentyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, 2-chloroethyl acrylate, 2-methoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, proyl methacrylate,
inglovir methacrylate, inbutyl methacrylate,
Inbutyl methacrylate, tert-butyl methacrylate, neopentyl methacrylate, pentyl methacrylate, diuryl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2-methacrylate
Acrylic esters and methacrylic esters such as chloroethyl, 2-methoxyethyl methacrylate, and ethyl methacrylate; a-methylstyrene, vinyltoluene, 4-bromustyrene, 4-chloro-5-fluorostyrene, 2-chlorostyrene , 2.5-dichlorostyrene, 2. s-difluorosterene, 2,4-dimethylstyrene, 4-ethoxystyrene, 4-ethylstyrene, 4
- Styrenes such as iodostyrene and 4-nonadecyl styrene; Vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ether ketone, and vinyl isopropenyl ketone. Class 7; Propylene, ethylene,
Examples include unsaturated hydrocarbons such as isophrene and butadiene. These monopolymerizable monomers can be used alone or in a suitable combination of two or more types. When the copolymer is constituted by coalescence, the content ratio of the fiber-containing vinyl monomer in the copolymer is preferably 50 mol or more, particularly preferably 70 mol or more. Further, the weight proportion of fluorine atoms in the copolymer is preferably 15 to 60% by weight.

The magnetic fine powder used in the carrier used in the method of the present invention includes substances that are strongly magnetized in the direction of a magnetic field;
For example, ferrite, magnetite, iron,
Ferromagnetic metals such as cobalt and nickel, alloys or compounds containing these metals, ferromagnetic elements t-
Alloys that do not contain ferromagnetic gold but become ferromagnetic by proper heat treatment, such as Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin, or alloys such as chromium dioxide, etc. Powders may be mentioned. The average particle size of such fine magnetic powder is preferably about 0.05 to 3 μm, and the content of fine magnetic powder is preferably Fi2 (1 to 300 parts by weight based on parts by weight of binder resin Inn). parts, particularly preferably 50 to 150 parts by weight.

As a method for manufacturing the carrier used in the method of the present invention, conventionally known general toner manufacturing methods can be applied as is. That is, for example, the binder resin, magnetic fine powder, and other additives to be added as necessary are premixed in a ball mill or the like all around the body to be uniformly mixed and dispersed.

Next, the mixture is kneaded using heated rolls, and then cooled and crushed. Next, in order to obtain carriers with a desired particle size, they are classified according to necessity, and carriers with an average particle size of 10 to 50 μm are classified.
jlli build.

The average particle size of the carrier used in the method of the present invention is 10 to 50μ
The particle diameter is preferably 15 to 40 μm, and the particle size is preferably uniform.

In addition, it is preferable that the carrier used in the method of the present invention has a spherical shape because it can improve fluidity, and such a spherical carrier can be obtained, for example, by the above-mentioned manufacturing method. A preferred method is to further spray the pulverized carrier particles into hot air using a known spray dryer or the like to instantaneously melt the surface of the carrier particles and make the carrier particles spherical by surface tension. .

Other manufacturing methods for the carrier used in the method of the present invention include a method in which a monomer component of a binder resin is polymerized to form a polymer in the presence of fine magnetic powder;
This method is preferred because it is industrially stable and easy to manufacture. Specifically, the following methods can be mentioned, for example.

0) A method in which ordinary bulk polymerization is carried out without a solvent at a temperature of 611 to 120°C under a nitrogen stream.

(b) In water at a temperature of 60 to 12°C (1°C) under a nitrogen stream, for example, gelatin, starch, polyvinyl alcohol, barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, calcium phosphate, talc, sticky material, silicic acid, or gold JI
A method in which suspension polymerization is carried out by a conventional method in the presence of a dispersant such as 6-dispersant powder.

(c) Emulsion polymerization is carried out by a conventional method at a temperature of 40 to 90°C under a nitrogen stream using an aqueous polymerization initiator in the presence of a surfactant such as sodium dodecylbenzenesulfonate, an alkyl sulfate type anionic emulsifier, and sodium dodecylsulfonate. How to do it.

B) A method in which solution polymerization is carried out by a conventional method under a nitrogen stream at a temperature of 60 to 1.20° C. in a diluted state with a suitable solvent (eg, evabenzene, xylene, ethanol, methyl ethyl ketone).

When manufacturing a 1:5 carrier ft using such method 17i, it is preferable that the fine magnetic powder used has a pH of 6 or more. Also most preferred! ! The manufacturing method is the method 0) above using a suspended heavy alloy.

Furthermore, if the magnetic fine powder is exposed in a bare state on the surface of the carrier particles, the triboelectric charging properties of the carrier particles may be adversely affected by the triboelectric charging properties of the magnetic fine powder. It is desirable to coat the surface of the fine magnetic powder with a resin or higher fatty acid before incorporating the entire powder into the binder resin. Examples of higher fatty acids that can be used for this purpose include stearic acid, fatty acid, oleic acid, and the like. Coating can be easily carried out by immersing the fine magnetic powder in a solution of these higher fatty acids dissolved in an organic solvent such as trichloroethylene or dichloroethane.

It is preferable that the carrier used in the method of the present invention has a glass transition temperature (Tg) of at least 600. If the glass transition temperature is low, heat will be generated due to friction between the carriers and friction between the carrier and the wall of the developing device. In this case, the carrier becomes sticky and has poor fluidity. The carrier used in the method of the present invention is preferably one that imparts an electric charge of 5 to 40 microcoulombs/l in absolute value to the toner used together under normal usage conditions.

It is made up of toner ore, which constitutes a two-component developer, along with the above 5 carriers, and toner components such as colorants are completely dispersed in a binder resin.As the binder resin, various thermoplastic resins are required. used. Specific examples thereof include, for example, methoxybenzene, parachlorostyrene,
Styrenes such as a-methylstyrene; methyl acrylate, ethyl acrylate, niprovir acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n methacrylate
-butyl, lauryl methacrylate, 2-ethylhexyl methacrylate, and other a-methylene fatty acid IF [monocarboxylic acid esters; acrylonitrile, methacrylonitrile, and other vinyl nitriles; 2-vinylpyridine, 4
- Vinylpyridines such as vinylpyridine; vinyl erthyls such as vinyl methyl ether and vinyl isobutyl ether: vinyl methyl ketone, vinyl ethyl ketone,
Methyl impropenyl ketone 'I Which vinyl ketones;
Monomers such as unsaturated hydrocarbons and their halides such as ethylene, propylene, isoprene, and butadiene, and halogen-based unsaturated hydrocarbons such as chloroprene,
or copolymers obtained by combining these monomers with t-28 or more, and mixtures thereof, such as rosin-modified phenol-formalin resins, oil i
Examples include non-vinyl condensation resins such as polyester epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, and polyether resins, or mixtures of these and the vinyl resins. Examples of colorants include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow,
Mention may be made of ultramarine blue, methylene blue, rose bengal, 7-talocyanine blue or mixtures thereof. Toner components other than the colorant may include minerals, charge control agents, anti-offset agents, fluidity improvers, etc., and if necessary, fine magnetic powder may be contained.

Such a toner can be obtained by a conventionally known toner manufacturing method, and has an average particle size of 20 μm or less, particularly 8 to 12 μm.
μm toner is preferred.

The mixing ratio of carrier and toner in the two-component developer used in the method of the present invention is not particularly limited, but is within a range where the mixing ratio C() - weight ÷ carrier weight) is expressed by the following formula: It is preferable to be inside.

ρT: toner density distribution: carrier density, more preferably 0 or more within the range expressed by the following formula.The two-component developer used in the method of the present invention has been described. 'The specific development process for developing the turtle image will be described.

The developer transport carrier for supplying developer to the entire development space is
A device similar to the conventional one capable of applying a bias pressure can be used, and in particular, a structure in which a rotating magnet having a plurality of magnetic poles is provided inside a sleeve that carries a developer layer on its surface. Gold can be preferably 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 successively supplied. Furthermore, even if there is some degree of non-uniformity in the layer thickness of the developer layer on the surface of the sleeve, its influence is sufficiently covered by the above-mentioned undulations so that it does not become a problem in practice.

It is preferable that the developer conveying speed 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. Further, it is preferable that the rotation of the rotating magnet body and the conveyance direction due to the rotation of the sleeve be in the same direction. When the same direction is the opposite direction, F also has excellent image reproducibility. However, it is not limited to these.

Further, it is preferable that the thickness of the developer layer supported on the developer transport carrier be uniform. For example, the developer adhering to the developer transport carrier may be sufficiently scraped off with a blade that regulates the thickness to make the thickness uniform. It is preferable to make the layer into a layer. The gap between the developer transport carrier and the electrostatic image carrier is several 10
~211 n nm is preferable, and if the gap between the developer transport carrier and the electrostatic image Jr4 carrier becomes too narrow by several 10 μmjυ, it will be difficult to form a magnetic band s that acts as a uniform -VC'gt image in the image space. In addition, it becomes difficult to supply a sufficient amount of toner particles during development, and as a result, it becomes difficult to perform stable development, and vice versa.
) When the temperature is increased so that the gap greatly exceeds 2000 μm, the opposing electrode effect decreases and sufficient image density cannot be obtained [
In addition, the edge effect in which more toner adheres to the contours of the electrostatic image than to the center also increases.

Also, the gap and the thickness of the developer layer are 1 when no oscillating electric field is applied, and the ear of the magnetic brush is on the surface of the electrostatic image carrier f! :
It is particularly preferable to set the conditions so that they do not touch each other, but are close to each other. This is due to the force required to prevent scratches and fogging caused by the rubbing of the magnetic brush on the toner image.

The oscillating electric field is preferably formed by applying an oscillating bias voltage to the sleeve of the developer transport carrier. Further, as the bias voltage, it is preferable to use a voltage that is a combination of a DC voltage that prevents toner particles from adhering to non-image areas and an AC voltage that 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 developing step in the method of the present invention is shown in FIG. In FIG. 1, l is a drum-shaped electrostatic image bearing member made of a photoreceptor such as 8e, which rotates in the direction of the arrow and rotates in the direction of the arrow. An electrostatic charge image is formed on the surface using an exposure device. Reference numeral 2 denotes a sleeve made of a non-magnetic material such as aluminum, and 3 a magnet body provided along the upper circumference of a plurality of N, 8 magnetic poles provided inside the sleeve 2. The sleeve 2 and the magnet body 3 form a developer transport carrier. is configured. These sleeve 2 and magnet body 3 are relatively rotatable, and in the illustrated example, sleeve 2 is rotated in the direction of the arrow, and magnet body 3 is fixed.

The ON and S magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 15 flO 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 20. .

Reference numeral 4 designates a regulating blade made of magnetic or non-magnetic material that regulates the height and size of the magnetic brush, and 5 a cleaning blade that removes the magnetic brush that has passed through the clear image space A from above the sleeve 2. The surface of the sleeve 29 is in contact with the developer pool in the developer reservoir 96, thereby supplying the developer. It is a stirring screw that makes the water uniform. When the developer reservoir 6 is developed, the toner particles T are consumed, so the toner particles T in the toner hopper 8 are replenished appropriately. 9 is a surface on which the toner particles T are dropped into the developer reservoir 6. It is a supply loan with a recess in .101
This is a bias power supply that applies the entire bias voltage to the sleeve 2K through the ζ resistance resistor II. AC component vibrated by this bias power supply 10? A bias voltage of 7 is applied between the sleeve 2 and the base 1a of the electrostatic image carrier 1, which is grounded.

As this bias voltage, for example, a weight voltage of a DC voltage and an AC voltage is used.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 potential of the non-image area, for example, 5A to 600V, is used, and for the AC voltage component, a frequency of 1 (1 ('lHz to 1Hz) is used.
10kHz, preferably 1-5kHzT: LnOV
~5KV] ttEEiz5 used.

If the DC voltage component contains toner particles or magnetic material, the non-image area electric potential may be low. If the frequency of the AC voltage component is too low, the effect of imparting vibration will be reduced by 7J, and if it is too high, the developer will not be able to follow the vibrations of the electric field, resulting in a decrease in image quality and a sharp, high-quality image. f) A tendency appears when it becomes impossible to obtain. In addition, the voltage of the current voltage component is also related to the frequency, but the higher the voltage, the more the magnetic brush can be vibrated, which increases the effect, but if it is too high, fogging is likely to occur, which can cause problems such as lightning strikes. This is not preferable because dielectric breakdown is likely to occur.

In the above-described apparatus, 1. The gap between the sleeve 2 and the electrostatic image carrier 1 is set to be in the range of several lO to 2000 μnt, and the electrostatic image on the electrostatic image carrier 1 is developed. Since the magnetic flux density on the surface of the magnetic brush formed on the surface of the sleeve 2 changes as the sleeve 2 rotates, the magnetic brush moves on the sleeve 2 while vibrating. As a result, the electrostatic charge image carrier 1 is stably and smoothly passed through the gap with the electrostatic charge image carrier 1, and at this time, a willow-like developing effect is imparted to the surface of the electrostatic charge image carrier 1, resulting in a stable and high level of development. Enables development of image density.

Although an example of the apparatus that can be used in the method of the present invention has been described above with reference to FIG. 1, the present invention is not limited thereto. For example, even if several electrode wires are stretched around the developing area between the developer transport carrier and the electrostatic image carrier and a vibrating voltage is applied to them, the magnetic brush is vibrated and the development effect is achieved. 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. Furthermore, the method of the present invention can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage approximately equal to the receiving potential in the non-image background portion of the electrostatic image carrier. Furthermore, the method of the present invention can be applied even when the image to be developed is a magnetic latent image.

[Function and effect of the invention]

The present invention is based on the method described above, and the carrier constituting the two-component developer is small-diameter particles in which fine magnetic powder is dispersed in a binder resin, and the binder resin has a specific content. Since it is made of a polymer formed from fluorinated vinyl monomers, the carrier has excellent negative friction band properties, and therefore charges the toner with a sufficient amount of charge to the opposite polarity. This makes it possible to improve the adhesion of the toner particles to the latent image. Since the carrier has such excellent triboelectrification properties, it is either completely unpopular to include the charge control agent in the toner, or even if it is necessary, it may be necessary to use only a small amount. Therefore, the cause of contaminating the surface of the carrier is substantially eliminated, and as a result, the excellent friction band t% property of the carrier does not change, so that the charging of the toner becomes stable for a long period of time. Furthermore, in the development process, an oscillating electric field is applied to the developing space, so even though the toner particles are difficult to separate from the carrier particles due to the small diameter of the carrier, the oscillating electric field causes As a result of the particles and the carrier particles being vibrated while being subjected to forces in opposite directions, the toto particles separate from the carrier particles and behave as unit particles, which allows development to be carried out with a sufficient amount of toner adhesion. I can do it. As a result, the benefit of making the carrier smaller in diameter is that the toner concentration range in the two-component developer is wider and toner replenishment becomes easier. It is possible to stably form clear, high-density, fog-free images over a long period of time while obtaining high density images. However, since toner is consumed along with image formation, even if carrier material were to adhere to the surface of toner particles, it would be a major problem. The impact is small and does not actually pose a problem.

[Embodiments of the invention]

Specific examples of the present invention will be described below, but the present invention is not limited to these examples. Furthermore, “department”
represents "parts by weight".

Example 1 Styrene, methyl methacrylate and exemplary compound (M-14
) and 50 parts of a copolymer obtained by polymerizing them at a weight ratio of 60:20:20 and magnetite
-1!1iPJ (manufactured by Titanium Kogyo Co., Ltd.) (50 parts) and subjected to a ball mill for about 24 hours, kneaded using hot rolls, cooled and pulverized, and then the obtained powder was sprayed into hot air. After drying and classifying, the spherical carrier having an average particle size of 25 μm was advanced.

85 copies of this carrier and an electrophotographic copying machine [U-Bix]
A two-component developer was produced by FA by mixing with 15 parts of toner for 1600J (Konishi Roku Photo Industry Co., Ltd. #), and this developer was used to produce an electrophotographic copy @ equipped with a developing mechanism similar to that shown in Fig. 1.
When a live photo test was carried out using a modified rU-Bix t6no machine, the images obtained were very clear and had no edge effects or fog and were of extremely high density. 1 5
After continuous printing 10,000 times, it was possible to obtain good images that were stable and unchanged from beginning to end.

In this example, the developing conditions are as follows. That is, the electrostatic charge gI! The carrier is an organic photoconductive photoreceptor C having a negatively charged two-layer structure, which uses an anthrone pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance. ),
The circumferential speed of the oPc photoconductor is 18Qlul/ @ e C
, the highest potential of the electrostatic image formed on the electrostatic image carrier is -50 oV, the outer diameter of the sleeve is 30 mm, the rotation speed of the sleeve is 1 (10 rpm, N of the magnet body, the magnetic flux density of the 8 magnetic poles is 900 Gauss, The thickness of the developer layer in the development space is 05 m, the gap between the sleeve and the electrostatic image carrier is 700 μm, and the bias voltage applied to the sleeve has a DC voltage component of 1250 V.
, AC voltage component is 1.5kHz, 500V
=.

Example 2 A carrier #1 was produced in the same manner as in Example 1 except that Exemplified Compound (M-20) was used instead of Exemplified Compound (M-14) in Example 1.

A developer was prepared using this carrier in the same manner as in Example 1, and a photographic test was conducted, and as in Example 1, good results were obtained.

Example 3 A carrier was produced in the same manner as in Example 1, except that Exemplified Compound (M-30) was used in place of Exemplified Compound (N-14) used in Example 3.

A developer was prepared using this carrier in the same manner as in Example 1, and a photographic test was conducted, and as in Example 1, good results were obtained.

Comparative Example 1 A carrier was entirely produced in the same manner as in Example J except that n-butyl methacrylate was used instead of the exemplary compound (M-14) in Example 1.

When a developer was prepared using this carrier in the same manner as in Example 1 and all photographic tests were carried out, the resulting images had a lot of fog and low image density. Note that this image was a reversed image.

Example 4 In a 1.23% polyvinyl alcohol aqueous solution, 150 parts of magnetite [Mapico Black BL-1nnJ (Titan Kogyo Co., Ltd.), 50 parts of styrene, 15 parts of methyl methacrylate, and 35 parts of exemplified compound (M-4) were added. and 1 part of benzoyl peroxide and stirred at 3110 + 1 rpm using a zTK homogenizer (manufactured by Tokushu Kogyo Co., Ltd.).
The temperature was raised to 0°C and polymerized for 6 hours, and after completion of polymerization, polymer particles t
A carrier having an average particle size of 20 μm was produced by separating the mixture with F and drying.

On the other hand, styrene-methyl methacrylate-methacrylic acid n
-Butyl copolymer (weight ratio 5 (1: 211 230)
100 parts of carbon black [Mogul LJ (manufactured by Cabot Corporation)] 1 part and 3 parts of low-molecular-weight polyglobylene "Viscol 66 (IPj (manufactured by Sanyo Chemical Industries, Ltd.)) were mixed in a ball mill, mixed, crushed, A toner having an average particle size of 10 .mu.m was produced by carrying out all the classification operations.20 parts of this horse chestnut and 80 parts of the # carrier were mixed to prepare a developer.

Using this developer, a developing mechanism similar to that shown in Fig. 1 is provided and OP
Electrophotographic copying machine "U-Bix2so" equipped with C photoreceptor
o'' (Konishi Roku Photo Industry Co., Ltd.) When we conducted a live-photography test using a modified machine, the images obtained were clear, high-density images without edge effects or capri, and the images were continuously copied 6ooooo times. There was no deterioration in image quality even after the image was removed.The developing conditions were the same as in Example 1.

Example 5 Styrene, methyl methacrylate and exemplary compound (M-23
) and 60 parts of a copolymer obtained by polymerizing them at a weight ratio of 75:10:15 and magnetite [Toda Color EPT-5
(40 parts of IOJ (manufactured by Padako'iM)) was mixed with a ball mill for about 24 hours, kneaded with hot rolls, cooled, and pulverized, and the resulting powder was sprayed into hot air. After drying, it was classified to produce a carrier having an average particle size of 20 μm.

Using this carrier, a developer was prepared in the same manner as in Example 4, and a photocopying test was conducted. As in Example 4, a good copy image was obtained.

Comparative Example 2 Spherical iron powder r [5P-135CJ (manufactured by Dowa Iron Powder Industries Co., Ltd.) 100 A carrier IJ with a film thickness of approximately 2 μm was fabricated by coating the portion.

A developer was prepared by mixing 98 parts of this carrier with 2 parts of the toner used in Example 4, and when a photocopying test was conducted in the same manner as in Example 4, unevenness occurred in the image.
Moreover, when the live-action test was repeated many times, the image quality of the obtained images fluctuated and became unstable.

[Brief explanation of drawings]

FIG. 1 is a schematic illustrative cross-sectional view of an example of a developing apparatus that can be used to carry out the developing process in practicing the method of the present invention. . l...Static charge 1#! Carrier 2... Sleeve 3
, ... Magnet body 4 ... Regulation blade 5
... Cleaning blade 6 ... Developer reservoir 7 ... Stirring screw 8 ... Toner hopper 9 ... Supply roller 1
0...Bias power supply 11...Conservation resistance A.
...Development space D...Developer T...Toner particles N8...Magnetic pole decoy

Claims (1)

[Claims] 1) A developer layer of a two-component developer consisting of toner and carrier is formed on a developer transport carrier, and this developer layer is supplied to a development space in which an oscillating electric field is generated. In an image forming method including a developing step of developing a latent image on a latent image carrier, the carrier 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; An image forming method characterized in that the binder resin is a polymer obtained from a fluorine-containing vinyl monomer represented by the following general formula (1). General formula (1) ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [In the formula, R represents a hydrogen atom or a methyl group, X represents an oxygen atom, a COO group, or a CO group, and Rf represents a fluoroalkyl group. ]