JP2741602B2 - Multicolor electrophotographic color developer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a developer used for developing an electric latent image or a magnetic latent image in electrophotography, electrostatic printing, or the like, and particularly to a multicolor developer. The present invention relates to a color developer for multicolor electrophotography using a color developer having significantly improved image quality of a color image.

[Prior Art] Conventionally, as a method for developing an electrostatic latent image using toner in electrophotography, a method using a so-called two-component developer in which a small amount of toner is dispersed in a medium called a carrier, and a method using a carrier are described. There is a method using a so-called one-component developer which uses toner alone without using it. The present invention relates to a two-component developer comprising a toner and a carrier among the above-mentioned developers. The carrier constituting the two-component developer is roughly classified into a conductive carrier and an insulating carrier. As the conductive carrier, oxidized or unoxidized iron powder is usually used. In
There is a drawback that the triboelectric charging property with respect to the toner is unstable and that a visible image formed by the developer is fogged. That is, with the use of the developer, toner particles adhere and accumulate (spent toner) on the surface of the iron powder carrier particles, so that the electric resistance of the carrier particles increases, the bias current decreases, and the triboelectric charging property is increased. Becomes unstable, and as a result, the image density of the visible image formed decreases and fog increases. Therefore, if the copying operation is continuously performed by an electronic copying apparatus using a developer containing an iron powder carrier, the developer deteriorates in a small number of times, so that it is necessary to replace the developer at an early stage, resulting in a high cost. It will be.

A typical example of the insulating carrier is a carrier in which the surface of a carrier core material made of a ferromagnetic material such as iron, nickel, or ferrite is uniformly coated with an insulating resin. In the developer using this carrier, toner particles are less likely to fuse to the carrier surface than in the case of the conductive carrier, and at the same time, it is easy to control the triboelectric charging property between the toner and the carrier, and the durability is high. This is advantageous in that it is particularly suitable for high-speed electronic copiers in that it has excellent service life and a long service life.

However, in this insulating carrier, a coating layer covering the surface of the carrier core material is uniform, and a desired size and a charged state of polarity can be stably obtained by friction with a specific color toner used with the carrier. Required. That is, if the surface of the resin-coated carrier is non-uniform, the triboelectric charging between the color toner and the carrier becomes unstable, and as a result, the image quality of a visible image obtained after copying is reduced.

Therefore, for the purpose of making the carrier surface after resin coating uniform, it has been attempted to coat the resin after smoothing the surface layer of the carrier core material itself. Although the uniformity is obtained, the adhesiveness between the carrier core material and the coating resin becomes unstable, and the usable coating resin is limited to only the resin having good adhesiveness. If the amount of the coating resin is increased to further increase the coating strength, the carrier itself is strongly charged to the opposite polarity to the toner particles due to the insulating property of the coating resin, which causes a problem of carrier adhesion to the background portion. I will.

On the other hand, it has been proposed to disperse, for example, conductive carbon black or the like in a coating resin for the purpose of eliminating carrier adhesion caused by the carrier itself being strongly charged. It cannot be said that a stable coating state is always achieved, and new problems such as fogging due to release of carbon black and the like due to long-term use have occurred.

As described above, the carrier core material surface layer and the characteristics of the resin-coated carrier have a close relationship. However, for the surface layer of the carrier core material, for example, a spherical magnetite is used as a carrier in JP-A-61-151551. Although the layer is limited in terms of porosity, the proposal merely discloses the percentage of vacancies, does not refer to the diameter of each vacancy, and defines the surface state of the carrier core material. Is inappropriate.

As described above, there is no example describing the correlation between the surface state of the carrier core material and the electrophotographic characteristics, but the findings obtained as a result of intensive studies by the present inventors are as follows.

It has been found that the surface state of the carrier core material and the pore size distribution on the surface of the carrier core material are very correlated. If the average pore size on the surface of the carrier core material is too large, the carrier core material is too smooth and coated with the carrier core material. Adhesion with resin decreases, and
If the average pore size on the surface of the carrier core material is too small, the uniformity of the coating resin on the carrier core material is impaired, and as a result, the triboelectric charging characteristics between the non-magnetic color toner and the carrier particles become unstable, which may be obtained in copying. It has been found that fog in a visual image, a decrease in image density, and further, carrier adhesion on a latent image carrier occur, thereby significantly impairing the quality of a multicolor image.

[Problems to be Solved by the Invention] The present invention is to provide a developer free from the above-mentioned drawbacks, and to provide a developer having stable triboelectric charging characteristics and excellent carrier adhesion prevention.

Another object of the present invention is to provide a color developer having a high image density, no fog, excellent color mixing, and particularly excellent transparency in OHP.

Another object is to provide a color developer with less toner scattering.

It is another object of the present invention to provide a long-life color developer having a stable developing ability due to the fact that toner spent hardly occurs on the surface of carrier particles and the carrier coating resin adheres firmly.

[Means and Actions for Solving the Problems] That is, the present invention includes a toner charged to the same polarity as the electrostatic image potential on the electrostatic image carrier and a carrier charged to the opposite polarity to the toner. The developer is carried on the surface of the developer carrying member, and an alternating electrolysis having an alternating current component and a direct current component is formed in the developing section, and the electrostatic image on the electrostatic image carrier is developed on the developer carrying member. Used in a developing method of developing with a developer, the developer having a volume average particle size of at least 4 to 10 μm.
And a carrier obtained by coating a carrier core material having a weight average particle diameter of 30 to 65 μ with an electric insulating resin in an amount of 0.1 to 5.0% by weight based on the weight of the carrier core material. In the weight distribution, the content of the carrier core material having a weight distribution of 35 μm or less is 1 to 5% by weight, the average pore diameter on the surface of the carrier core material is 1500 ° to 25000 °, and the carrier has at least a hydroxy group. Polymerized with at least one monomer selected from monomers of acrylic acid or its esters and methacrylic acid or its esters, and at least one monomer selected from styrene monomers Coating with a resin containing copolymer A obtained by the above method, and then coating a polymer blend of resin B containing fluorine and a copolymer A with fluorine charged to the opposite polarity to that of copolymer A. The present invention relates to a color developer for multicolor electrophotography, which is a resin-coated carrier.

When the average pore diameter of the carrier core material surface is less than 1500 mm, the unevenness on the core material surface increases, and the coating state of the electrically insulating resin becomes very uneven at the unevenness, and the triboelectric charge amount is extremely unstable and good. Images cannot be obtained. Conversely, if the average pore diameter is larger than 25000Å, the coating state is stable, but the adhesion of the coating resin to the carrier core material is reduced,
Lack of stability in long-term use causes problems such as fog and toner scattering. However, the average pore diameter of the carrier core material surface in the present invention is 1500 ~ 25000 Å, preferably 5
It is better to be in the range of 000 to 2000 mm.

As the carrier core material used in the present invention, for example, metals such as surface-oxidized or unoxidized iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earths, and alloys or oxides thereof and ferrites can be used. . There is no particular restriction on the manufacturing method.

Further, in the present invention, the surface of the carrier core material is coated with a resin or the like, as a method of dissolving or suspending a coating material such as a resin in a solvent and applying the solution to adhere to the carrier core material, Any conventionally known method such as a method of simply mixing with a powder can be applied, but it is more preferable that the coating material be dissolved in a solvent for the stability of the coating layer.

In particular, in the present invention, the most stable coated carrier can be obtained when it contains an acrylic monomer containing a hydroxy group in order to improve the adhesion to the carrier core material. Such acrylic monomers include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
2-hydroxymethyl methacrylate, 2-hydroxypropyl methacrylate and the like are suitable.

As the material of the carrier core material used in the present invention, 98
% By weight or more Cu-Zn-Fe composition ratio (5-20): (5-2
0): Ferrite particles having a composition of (30 to 80)｝ are particularly preferable in that they can easily make the surface uniform and have stable chargeability and can stabilize the coat. It is most preferable to use an acrylic resin or a styrene-acrylic resin copolymer as the compound on the side and a silicone resin polyvinylidene fluoride or a polyvinylidene fluoride-polytetrafluoroethylene copolymer as the compound on the negative charge side.

In particular, in the present invention, in order to improve the adhesiveness to the carrier core material surface, the positively charged compound is a monomer of at least a hydroxy group-containing acrylic acid or its ester and a methacrylic acid or its ester. A resin containing a copolymer obtained by polymerizing at least one monomer selected from monomers and at least one monomer selected from styrene-based monomers is a carrier core material due to the effect of the hydroxy group. And the adhesiveness with the adhesive.

Further, the surface of the carrier core is 0.
The step of coating with an electrically insulating resin of 1 to 5.0% by weight is at least twice or more, and the acrylic resin containing at least a hydroxy group of 30 to 60% by weight of the total coating resin of the carrier core material in the first coating step. Obtained by polymerizing at least one monomer selected from an acid or ester monomer and methacrylic acid or an ester monomer and at least one monomer selected from styrene monomers The resin containing the copolymer is coated, and in the second and subsequent coating steps, 70 to 40% by weight of the total coating resin of the carrier core material is a monomer of acrylic acid or an ester thereof containing at least a hydroxy group and A copolymer obtained by polymerizing at least one monomer selected from methacrylic acid or its ester monomer and at least one monomer selected from styrene monomers The polymer containing the resin and the fluorine-containing resin charged to the opposite polarity to the copolymer with respect to the surface of the carrier core material in the range of 30:70 (weight ratio) to 70:30 (weight ratio). It is more effective to cover the blended electrically insulating resin.

This is because, in order to compensate for the poor adhesion of the fluorocarbon resin to the carrier core, the surface of the carrier core is coated with a resin containing a hydroxy group having good adhesion to the carrier core before the non-magnetic toner. In particular, by coating the carrier surface with a negatively-chargeable fluorine-based resin that suppresses excessive charging of the negatively-charged toner, the fluorine-based resin is easily exposed to the carrier particle surface layer, and at the same time, stable coating is achieved. It is.

The amount of the resin to be treated may be appropriately determined so that the carrier satisfies the above-mentioned conditions. In general, the total amount is desirably 0.1 to 5% by weight (preferably 0.3 to 3% by weight) with respect to the carrier of the present invention.

The weight average particle size of the carrier core material is 30 to 65 μ, preferably
It is preferably from 40 to 60μ. Further, the carrier core material has a particle size of 35 μm or less in a weight distribution of 1 to 5% by weight, and a weight distribution of a particle size of
Not less than 20% by weight and a particle size of 74 μm
When the content is 5% by weight or less, a good image can be maintained.

That is, in the present invention, in order to obtain a good multicolor image, sharp-melting colorant-containing resin particles are used, but the colorant-containing resin particles are extremely fused on the latent image carrier. Cheap. However, when the colorant-containing resin particles fuse to the latent image carrier, electric charges are accumulated on the latent image carrier.
| V _DC −V _D | exceeds 200V. | V _DC −V _D | is 200V
Is exceeded, the carrier core material having a size of 35 μm or less adheres to the latent image carrier, and the effect of scraping off the fused material on the latent image carrier is exhibited, thereby eliminating image defects.

At this time, the carrier core material having a weight distribution of 35 μm or less is 5%.
Is exceeded, | V _DC −V _D | also adheres to portions smaller than 200 V, causing problems such as image defects and drum scraping.

On the other hand, if the carrier core material having a particle diameter of 35 μm or less is less than 1%, the effect of polishing the magnetic particles is insufficient, and it is not possible to eliminate the image defect by shaving off the fused material.

In the present invention, the carrier core material having a size of 35 μm or less is 1 to 5%.
Is that the volume average particle size of the colorant-containing resin particles is 4 to
It is more effective in the case of 10 μm. This is 4-10μ
This is because the colorant-containing resin particles having a small particle size of m have a small particle size, so that the adhesive force with the latent image carrier is strong and it is easier to fuse.

Here, the particle diameter of the colorant-containing fine particles used in the present invention is preferably 4 to 10 μm in volume average particle diameter, and 1.0% or less in a volume distribution of coarse powder of 20.2 μm or more.

Since the particle size is small, toner adherence to a minute electrostatic latent image is faithful, and disturbance of toner adherence at the end of the electrostatic latent image is small. As a result, an image with high resolution and good color reproducibility can be obtained. In particular, in a photographic image, there are many halftone areas, which are collections of minute latent images, and the effect of the particle diameter is further exhibited, resulting in a good image.

Examples of the binder used in the colorant-containing resin particles used in the present invention include polystyrene, poly-p-chlorostyrene, polyvinyltoluene, styrene-p-chlorostyrene copolymer, and styrene-vinyltoluene copolymer. Homopolymers of styrene and its substituents and copolymers thereof; styrene-methyl acrylate copolymer, styrene
Ethyl acrylate copolymer, styrene-acrylic acid-n
A copolymer of styrene and an acrylate such as -butyl copolymer; a styrene-methyl methacrylate copolymer,
Copolymers of styrene and methacrylic ester such as styrene-ethyl methacrylate copolymer and styrene-methacrylic acid-n-butyl copolymer; multi-component copolymers of styrene with acrylate and methacrylate; other styrene -Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-butadiene copolymer, styrene-vinyl methyl ketone copolymer, styrene-acrylonitrile-indene copolymer, styrene-
Styrene copolymers of styrene and other vinyl monomers such as maleic ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyester, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid, Phenol resins, aliphatic or alicyclic hydrocarbon resins, petroleum resins, chlorinated paraffins, and the like can be used alone or in combination. In particular, low-molecular-weight polyethylene, low-molecular-weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, higher fatty acid, polyamide resin, polyester resin, etc. are used as binder resins for toners subjected to the pressure fixing method. They can be used alone or in combination.

Particularly preferred resins for the practice of the present invention include styrene-acrylate resins and polyester resins.

In particular, (Wherein R is an ethylene or propylene group, x, y
Is an integer of 1 or more, and the average value of x + y is 2 to 10. A) a carboxylic acid component consisting of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid,
A polyester resin obtained by at least co-condensation polymerization with maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc. is more preferable since it has sharp melting characteristics.

In particular, the apparent viscosity at 90 ° C. is 5 × 10 ^{4 to} 5 × 10 ⁶ poise, preferably 25 × 10 ⁴ to 5
2 × 10 ⁶ poise, more preferably 10 ⁵ to 10 ⁶ poise, and the apparent viscosity at 100 ° C. is 10 ^{4 to} 5 × 10 ⁵ poise, preferably 10 ^{4 to} 3.0 × 10 ⁵ poise, more preferably 10 ⁴ poise. ~ 2
× 10 ⁵ poise color OHP with good transparency
And good results of fixing property, color mixing property and high-temperature offset resistance can be obtained even as a full-color toner.

In particular the absolute value of 2 × 10 ⁵ <of the difference between the apparent viscosity P ₂ at apparent viscosity P ₁ and 100 ° C. at 90 ° C. | preferably in the range of ^{_{<4 × 10 6 | P 1}} -P 2.

The toner according to the present invention may contain a charge control agent for stabilizing the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable.
In the present invention, when a negatively charged developer is used, the present invention becomes more effective. In this case, as the negatively charge controlling agent, for example, a metal complex of an alkyl-substituted salicylic acid (for example, di-
Chromium or zinc complex of tert-butylsalicylic acid)
And organometallic complexes such as When the negative charge control agent is blended in the toner, 0.1 to 100 parts by weight of the binder resin is used.
It is preferable to add 10 parts by weight, preferably 0.5 to 8 parts by weight.

When a two-component developer is prepared by mixing a toner and a carrier, the mixing ratio is determined as the toner concentration in the developer.
2.0% to 12% by weight, preferably 3% to 9% by weight
In general, good results are obtained. 2.0 toner density
%, The image density is too low to be practical, and above 12%, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

As the coloring agent used in the present invention, known dyes and pigments, for example, phthalocyanine blue, indaslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be widely used. .
The content thereof is not more than 12 parts by weight, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to reflect sensitively on the permeability of the OPH film.

Hereinafter, the phenomenon in the developing section of the developing method according to the present invention will be described.

FIG. 2 and FIG. 3 are enlarged explanatory views of the developing section in the developing method according to the present invention. Reference numeral 14 denotes a latent image charge of a bright portion on the latent image holding member. Reference numeral 12 denotes a toner. Reference numeral 13 denotes an alternating voltage power supply on which a DC component is superimposed. FIG. 2 shows a case where a negative waveform component of the alternating voltage is applied to the sleeve 11, and FIG. 3 shows a case where a positive waveform component of the alternating voltage is added. The polarity of the latent image charge is shown as minus, and the polarity of the developer is shown as minus.

Since the resistance of the developing brush 15 is relatively large (greater than about 10 ¹² Ωcm), the developing brush 15 has a triboelectric charge with the toner 12 depending on the charge / discharge time constant of electricity by the material and the like of the developing brush 15 itself. Alternatively, there is a mirror charge, a charge injected by a latent image electric field on the latent image holding member 10 and an alternating electric field between the latent image holding member 10 and the sleeve 11.

When the electric field due to the latent image charge 14 in the bright portion on the latent image holding member 10 does not coincide with the electric field due to the alternating electric field, the developing brush 15 is in a state of maximum bending in the direction of the sleeve 11.

When the direction of the electric field due to the latent image charge on the latent image carrier 10 and the direction of the electric field due to the alternating electric field match, the bending of the developing brush 15 becomes small, and the developing brush 15 comes into contact with the latent image carrier.

In any case, the brush produced by the alternating electric field as described above
Reference numeral 15 denotes a fine but violent vibration state, and the fog toner excessively attached on the latent image holding member is slid by the developing brush, removed from the latent image holding member 10, and pulled back onto the brush. In addition, the above-described vibration of the brush makes it easier for the toner to separate from the brush 15 and to be easily supplied to the latent image holding member 10, thereby improving the image density. Also brush 15
Due to the above vibration, the toner is loosened in the brush 15, which contributes to improvement of image density and prevention of ghost. further,
When the vibration state is severe, a part of the magnetic brush separates from the brush or the sleeve, and reciprocating motion occurs between the latent image holding member and the sleeve surface. The kinetic energy of the reciprocating brush is large, and the effect of the above-described vibration is expected efficiently. The behavior of the carrier particles in the developing section described above is a phenomenon observed as a result of high-speed shooting of 8000 frames per second with a high-speed camera.

In order to remove the discharge between the sleeve and the latent image carrier due to the alternating electric field as the carrier particles used in the present invention, it is desirable to have an electrically high resistance, and the surface is entirely or partially coated with an electrically insulating resin. It is preferred that Here, the electrical insulation is 10 ¹² Ωcm or more, preferably 10 ¹⁴ Ωcm.
Refers to Ωcm or more.

Hereinafter, each measurement method (1) to (4) of the present invention will be described.

(1) Particle size distribution measurement: Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting a number average distribution and a volume average distribution and a CX-1 personal computer (manufactured by Canon) ) And the electrolyte is 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride.

As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 0.5 to 50 mg of a measurement sample is further added.

The electrolyte in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II was used to perform 2 to 4 using a 100 μ aperture as an aperture.
The volume average distribution and the number average distribution are determined by measuring the particle size distribution of 0 μm particles.

From the obtained volume average distribution and number average distribution, the volume average particle size, the number average distribution 6.35μ or less, the volume average distribution
Each value of 20.2μ or less is obtained.

(2) Measurement of triboelectric charge: The measurement method will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of an apparatus for measuring a triboelectric charge amount of a toner. First, in a metal measuring container 2 having a 500-mesh screen 3 at the bottom, a mixture of a toner and a carrier in a weight ratio of 1: 9 to be measured for triboelectric charge is put into a polyethylene bottle having a volume of 50 to 100 ml. Shake by hand for about 10 to 40 seconds, add about 0.5 to 1.5 g of the mixture (developer) and close the metal lid 4. At this time, the weight of the entire measuring container 2 is weighed and W ₁
(G). Next, in the suction device 1 (at least a portion in contact with the measurement container 2 is an insulator), the air is adjusted through the suction port 7 to prepare the air volume control valve 6, and the pressure of the vacuum gauge 5 is set to 250 mmAq. In this state, suction is sufficiently performed, preferably for about 2 minutes, to remove the toner by suction. The potential of the electrometer 9 at this time is set to V (volt). Here, 8 is a capacitor whose capacity is C
(ΜF). Further, the weight of the whole measurement container after suction is weighed to be W ₂ (g). The triboelectric charge of this toner (μc /
g) is calculated as follows.

(However, the measurement conditions are 23 ° C. and 60% RH.) (3) Apparent viscosity measurement: Use a flow tester CFT-500 type (manufactured by Shimadzu Corporation). The sample weighs about 1.0 to 1.5 g of a 60mesh pass product. This is pressed for 1 minute at a load of 100 kg / cm ² using a molding machine.

The pressurized sample is subjected to a flow tester measurement under the following conditions under normal temperature and normal humidity (temperature: about 20 to 30 ° C., humidity: 30 to 70% RH) to obtain a humidity-apparent viscosity curve. From the obtained smooth curve, the apparent viscosities at 90 ° C. and 100 ° C. are determined and are defined as the apparent viscosities for the temperature of the sample.

RATE TEMP 6.0 D / M (℃ 1 minute) SET TEMP 70.0 DEG (℃) MAX TEMP 200.0 DEG INTERVAL 3.0 DEG PREHEAT 300.0 SEC (second) LOAD 20.0 KGF (kg) DIE (DIA) 1.0 MM (mm) DIE (LENG) 1.0 MM PLUNGER 1.0 CM ² (cm ² ) (4) Measurement of carrier particle size distribution (based on JIS-J2601) 1. Weigh carrier particles to the order of 100 g and 0.1 g.

2. Use standard sieves of 100 Mesh to 500 Mesh (hereinafter referred to as sieves), stack them in order of size 100, 200, 250, 350, 400, 500 from the top, place a saucer on the bottom, and put the carrier particles in the top sieve and cover.

3. This is shaken by a vibrator at 285 ± 6 horizontal revolutions per minute and 150 ± 10 impulse revolutions per minute for 15 minutes.

4. After sieving, measure the iron powder in each sieve and tray to the nearest 0.1 g.

5. Calculate to the second decimal place by weight percentage and round to the first decimal place according to JIS-Z8401.

However, 1. The size of the sieve frame shall be 200 mm in inner diameter above the sieve surface and 45 mm in depth from the upper surface to the sieve surface. 2. The total weight of iron powder in each part shall be It should not be less than 99% of the mass.

(5) Carrier electrical resistance measurement 1. Weigh about 1 g of resin.

2. Pack the toner in the cylindrical cell of the tablet for IR
It is pressurized at 0 kg / cm ² for 1 minute to obtain a molding device having a thickness of 0.5 to 1 cm. The diameter of the cell at this time is about 1.3 cm.

3. Apply conductive resin dootite to the molding device and fix it between the electrodes.

4. Apply an applied voltage of 100 V between the electrodes and read the current value one minute later.

5. The resistance value is calculated by the following formula.

Resin resistance S = surface area of molding machine (cm ² ) V = voltage (100 V) d = thickness (cm) i = current value (A) (6) Measurement of carrier average pore diameter Measurement of surface pore diameter according to the present invention Is a mercury intrusion porosimeter [Carlo Erba MER
CURY PRESSURE PORPSIMETER MOD 220].

Measurement of pore size by the mercury intrusion method is based on the properties of non-wetting liquids in capillaries. Liquids with a wetting angle of 90 ° or more cannot enter the pores themselves due to surface tension. Therefore, in order to put the liquid into the pores, it is necessary to apply pressure from the outside, and the pressure has a certain relationship with the pore diameter. The relationship between the applied pressure and the pore diameter (radius) is expressed by the following equation.

Pγ = 2σ · cos θ (1) γ = pore diameter [Å] σ = mercury surface tension: 480 [dyn / cm] θ = wetting angle with mercury: 141.3 [゜] P = applied pressure [kg / cm ^2] Substituting σ and θ into equation (1) gives:

γ = 7500 / P (2) Since the surface tension of mercury changes with temperature and the wetting angle also differs with the sample, the values used here are average values.

[Example] Hereinafter, an example of the present invention will be described in detail. Note that “%” and “parts” indicate “% by weight” and “parts by weight”.

Production Example 1 of Toner A polyester resin 100 obtained by condensing propoxylated bisphenol and fumaric acid 100 A phthalocyanine pigment 5 A chromium complex 4 of di-tert-butylsalicylic acid 4 is sufficiently premixed with a Henschel mixer, and at least 2 with a three-roll mill. The mixture was melt-kneaded more than once, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by an air jet pulverizer. Further, the obtained finely pulverized product was classified to select a particle size of 2 to 10 μm so as to have the particle size distribution of the present invention, thereby obtaining colorant-containing resin particles having a volume average particle size of 7.8 μm (namely, toner particles).

The apparent viscosity of the particles is 6.0 × 10 ⁵ poise at 90 ° C., 100
It was 1.1 × 10 ⁴ poise at ° C.

To 100 parts of the colorant-containing resin particles, 0.6 part of colloidal silica (primary particle size of 0.1 to 0.2 μ as observed by an electron microscope) was externally added to obtain a cyan toner.

Toner Production Example 2 In place of the phthalocyanine pigment, CI Pigment Yellow 173.5 parts was used to obtain a 7.6 μm yellow toner.

Toner Production Example 3 CI Solvent Red instead of phthalocyanine pigment
Use 0.9 part of 49, 1.0 part of CI Solvent Red 52 and 7.5μ
Magenta toner.

Production Example 4 Toner A 7.5 μm black toner was obtained by using 1.2 parts of CI Pigment Yellow 17, 2.8 parts of CI Pigment Red 5 and 1.5 parts of CI Pigment Blue 15 instead of the phthalocyanine pigment.

Production Example 1 of Carrier Copolymer A consisting of 10% by weight of 2-hydroxyethyl methacrylate, 60% by weight of methyl methacrylate and 30% by weight of styrene was prepared to have a weight average particle diameter of 52 μm and a particle diameter of 35 μm or less of 3.5%.
8% by weight, particle size 35-40μ is 8% by weight, particle size 74μ or more is 0.5%
Cu-Zn-Fe ferrite 100 having a particle size distribution of 100% by weight
After coating 0.5% by weight (based on the carrier core material) on a carrier core material (average pore diameter of 18000Å) by weight, the copolymer A and the vinylidene fluoride-tetrafluoroethylene copolymer B (copolymer molar ratio) 8: 2) in a weight ratio of 50:50 was coated with 0.5% by weight (based on the carrier core material) to obtain Carrier 1.

In the first coating step of the carrier core material, about 67% by weight of the copolymer A was coated, and in the second coating step, about 33% by weight of the copolymer A was coated.

Carrier Production Example 2 Carrier 2 was prepared in the same manner as in Production Example 1, except that 2-hydroxypropyl methacrylate was used instead of 2-hydroxyethyl methacrylate.

Production Example of Carrier 3 A carrier was produced in the same manner as in Production Example 1 except that the weight ratio of copolymer A and copolymer B was changed to 30:70.

Carrier Production Example 4 In Production Example 3, 1.0% by weight of copolymer A and copolymer B in a 30:70 weight ratio without coating of copolymer A (based on carrier core material). A carrier was produced in the same manner as in Production Example 3 except that the carrier B was coated to obtain Comparative Carrier 1. As a result, copolymer B released from the carrier core material was observed.

Carrier Production Example 5 A carrier was produced in the same manner as in Production Example 1 except that the mixing weight ratio of the copolymer A and the copolymer B was changed to 20:80, to obtain a comparative carrier 2. Copolymer B released from the material was observed.

Carrier Production Example 6 A carrier was produced in the same manner as in Production Example 1 except that a carrier core material having a particle size of 35 μm or less and 5.5% by weight was used.

Carrier Production Example 7 A carrier was produced in the same manner as in Production Example 1 except that a carrier core material having a particle size of 35 μm or less and 0.8% by weight was used, and Comparative Carrier 4 was produced.

Production Example 8 of Carrier In Production Example 1, 1% by weight was used without using copolymer B.
A carrier was produced in the same manner as in Production Example 1 except that the carrier core material was coated in a single coating step using the copolymer A (based on the carrier core material) to obtain a comparative carrier 5.

Production Example 9 of Carrier In Production Example 1, 0.04% by weight of copolymer A was used for the first time.
(Based on carrier core material) Same as Production Example 1 except that a second time, a 50:50 weight ratio of a polyblend of copolymer A and copolymer B was coated with 0.05% by weight (based on carrier core material). The carrier was manufactured as Comparative Carrier 6.

Production Example 10 of Carrier In Production Example 1, 2.3% by weight of copolymer A was added for the first time.
(Based on carrier core material) Same as Production Example 1 except that a second blend of 3% by weight (based on carrier core material) was obtained by polyblending copolymer A and copolymer B at a weight ratio of 50:50. When the carrier was manufactured as Comparative Carrier 7, the granulated material was extremely large and could not be used for evaluation.

Carrier Production Example 11 In Production Example 1, the carrier core material having an average pore diameter of 26000 変 え (weight average particle diameter of 55
μ, a particle size of 35 μm or less is 2.3% by weight, a particle size of 35 to 40μ is 9.5% by weight, and a particle size of 74 μm or more is 0.7% by weight. As a result, the adhesion of the coating resin was poor, and uniform coating could not be performed.

Carrier Production Example 12 In Production Example 1, the carrier core material having an average pore diameter of 1200 mm (weight average particle diameter 51 μm,
Particle size 35μ or less 2.8% by weight, Particle size 35-40μ 8.3% by weight,
First, 1.8% by weight of copolymer A (based on carrier core material), 50% by weight of copolymer A and copolymer B in the second time A carrier was produced in the same manner as in Production Example 1 except that 2.0% by weight (based on the carrier core material) of the polyblend was coated to obtain Comparative Carrier 9, and the surface of the carrier core material was too uneven and stable. No coated carrier was obtained.

Carrier Production Example 13 A carrier was produced in the same manner as in Production Example 1 except that in Example 1, 2-hydroxyethyl methacrylate was not used, but a copolymer C of 70% by weight of methyl methacrylate and 30% by weight of styrene was used. Thus, Comparative Carrier 10 was obtained.

Carrier Production Example 14 In Production Example 1, the carrier core material having an average pore diameter of 75,000 変 え (weight average particle diameter 55
μ, particle size 35μ or less 3.1% by weight, particle size 35-40μ 9.2% by weight, particle size 74μ or more 0.6% by weight). Standard) Carrier is produced in the same manner as in Production Example 1 except that the second time is coated with 1.5% by weight (based on carrier core material) of a polyblend of copolymer A and copolymer B at a weight ratio of 50:50. The carrier 4 was obtained.

In the first coating step of the carrier core material, about 57% by weight of the copolymer A was coated, and in the second coating step, about 43% by weight of the copolymer A was coated.

Table 1 shows the results of image formation using CLC-1 (manufactured by Canon) using each carrier shown in Carrier Production Examples 1 to 14. As the toner, full-color images were obtained using the four color toners shown in Toner Production Examples 1 to 4.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for measuring a triboelectric charge amount of a toner, and FIGS. 2 and 3 are enlarged explanatory views of a developing section of a developing method according to the present invention.

Claims (3)

(57) [Claims] A developer having a toner charged to the same polarity as the electrostatic image potential on the electrostatic image carrier and a carrier charged to a polarity opposite to the toner, carried on the surface of the developer carrying member; A developer used in a developing method for forming an alternating electrolysis having an AC component and a DC component in a developing unit and developing an electrostatic image on an electrostatic image carrier with a developer on a developer carrying member. The developer comprises at least a non-magnetic color toner having a volume average particle size of 4 to 10 μm and a carrier core material having a weight average particle size of 30 to 65 μm having an electrical insulation of 0.1 to 5.0% by weight based on the weight of the carrier core material. The carrier core material has a content of the carrier core material of 35 μm or less in the weight distribution of 1 to 5% by weight, and the average pore diameter of the surface of the carrier core material is 1500 mm. 225000Å, and the carrier comprises a carrier core At least one monomer selected from a group-containing acrylic acid or ester monomer and methacrylic acid or ester monomer, and at least one monomer selected from styrene monomers Coating with a resin containing a copolymer A obtained by polymerization, and then coating with a polymer blend of a resin A containing fluorine and a copolymer B having fluorine charged to a polarity opposite to that of the copolymer A A color developer for multicolor electrophotography, which is a resin-coated carrier obtained by the following method. 2. The carrier is coated with 30 to 60% by weight of copolymer A in the entire coating resin of the carrier core in the first coating step of the carrier core, and then coated with 70 to 40% by weight. The copolymer A and the fluorine-containing resin B were mixed at a ratio of 30:70 (weight ratio) to 7
2. The color developer for multicolor electrophotography according to claim 1, wherein the carrier is a resin-coated carrier coated with an electrically insulating resin polymer-blended within a range of 0:30 (weight ratio). . 3. A Cu—Zn—Fe containing 98% by weight or more of a carrier core material.
3. The color developer for multicolor electrophotography according to claim 1, wherein the core material is a ferrite carrier core material having the following composition.