JP2000010348A - Electrostatic developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the carrier drawing and toner scattering and stabilize the toner density and chargeability so as to be conformable to high printing rate print by specifying the toner density, and including a specified boron- containing organic matter in the toner particle. SOLUTION: In an electrostatic developer containing at least toner particle and a magnetic carrier particle, the magnetic carrier particle is a spherical particle, the toner density T/D (%) satisfies the expression T/D>Ceff, and the toner particle contains at least a boron-containing organic matter represented by the formula. Ceff represents 2.ρt/(2.ρt+X.ρc)×100(%), X represents R/r, T/D represents the toner particle weight content (%) in the developer, ρt represents the true density (g/cm3) of the toner particle, ρc represents the true density (g/cm3) of the magnetic carrier particle, R represents the average radius (μm) of the magnetic carrier particle, and (r) represents the average radius (μm) of the toner particle. In the formula, R1 and R4 represent hydrogen atom, an alkyl group or the like, R2 and R3 represent an aromatic ring, and X+ represents a cation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic developer used for developing an electrostatic latent image in an apparatus to which an electrophotographic method is applied, such as a copying machine and a printer.
More specifically, a full-color copying machine with a large print area ratio,
The present invention relates to an electrostatic developer used for a printer or the like.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat. No. 2,297,691.
No., JP-B-42-23910 and JP-B-43-2
As variously disclosed in, for example, Japanese Patent No. 4748, an electrostatic latent image is generally formed on a photoreceptor containing a photoconductive material by various means, and the latent image is previously stored in a carrier or a developing tank. The image is developed as a powder image with toner charged in contact with the wall, and if necessary, the powder image is transferred to paper or the like, and then fixed by heating, pressurizing, or solvent vapor. The toner is obtained by dispersing various dyes and pigments in a resin such as styrene acrylic or polyester.
A powder finely pulverized to about 30 μm, called a carrier, which carries toner to the vicinity of a photoreceptor by itself while carrying toner by electrostatic force on its surface, and has a powder diameter of 30 to 200 μm.
Magnetic-component development that is used as a two-component developer by mixing with iron powder, ferrite, and magnetite of about μm, or is replaced by magnetic powder that uses the carrier function in the toner powder without using a carrier. It is used as a non-magnetic one-component developer that is transported to the vicinity of an electrical latent image and developed by electrostatic adhesion only to the container wall of the developing tank without using a developer or magnetic force.

In a two-component developer using a toner and a carrier, when the toner is used for development and the toner concentration in the developer decreases, it is possible to supply the toner to the developer and use the toner while always maintaining the proper toner concentration. preferable. The replenished toner is quickly charged by contact with the carrier and used for development. If the toner is not rapidly charged, the toner scatters outside the developing tank, or adheres to a potential portion of the electric latent image where the toner should not be applied. In order to charge the toner quickly, the replenished toner needs to come into contact with the carrier surface and be charged. If the carrier particles are completely covered with the toner particles and the replenished toner particles cannot come into contact with the carrier, rapid charging cannot be expected. A method of calculating an appropriate upper limit of toner concentration is described in "Hoshi, Anzai: Effective Carrier Coverage of Two-Component Developer" (Journal of the Electrophotographic Society, Vol. 25, No. 4, (19)
86) p17) is generally known, and C eff = 2 · ρt / (2 · ρt + X · ρc) × 100
(%) X = R / r ρt: true density of toner particles (g / cm ³ ) ρc: true density of magnetic carrier particles (g / cm ³ ) R: radius of magnetic carrier particles (μm) r: toner particle It is said that the effective toner density C eff (%) calculated by the radius (μm) is the upper limit of the toner density that is practically used.

[0004]

In recent years, as copiers and printers have become full color and digitized, originals such as photographs and illustrations having a high solid printing rate have been increasingly printed. When printing with a high printing rate is performed, the consumption of toner from the developer increases, and a large amount of toner must be supplied. In that case, the following problems are likely to occur. 1. The toner supply to the developer cannot be completed in time, and the toner concentration decreases. 2. The replenished toner is not charged in time, and scatters or fog worsens. In order to solve Problem 1,
It is necessary to set the toner density to a high value so that the image density does not decrease so much even when the toner density is lowered in high printing rate printing. In order to solve the problem 2, it is necessary to set the toner concentration at a low level so that the replenished toner can quickly contact the carrier surface. The solutions to problems 1 and 2 are contradictory.

On the other hand, in a developing method using a two-component developer, a defect called “carrier pull” is known. When an electric latent image is developed with a developer, the developer is attached to a developing roller containing a magnet, the developer is brought into contact with or close to the surface of the photoreceptor on which the electric latent image is formed, and toner particles are formed by Coulomb force. A method of transferring to a photoreceptor is generally used. At this time, an undesired phenomenon in which a part of the carrier particles deviates from the magnetic binding force of the developing roll and is transferred to the photoreceptor is called "carrier pulling".

[0006] As a solution to the "carrier pulling", the magnetizing force of the magnet is increased, the magnetization of the carrier particles is increased,
There are known methods such as cutting small-sized carrier particles that are easy to "carrier pull" into a sharp particle size distribution, and selectively removing carrier particles with weak magnetization by magnetic separation. It is most effective to increase the average carrier particle size within a range that does not deteriorate. When the average carrier particle size is increased, the surface area per unit weight of the carrier is reduced, and the effective toner density C eff is reduced, so that it is more difficult to solve the above-described problem at the time of printing at a high printing ratio.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems of "carrier pulling" and "high printing rate printing" and to obtain a high-performance developer.
The present invention has been achieved by using toner particles containing a boron-containing organic substance having a specific composition and setting the toner concentration higher than the effective toner concentration. More specifically, in an electrostatic developer containing at least toner particles and magnetic carrier particles, the magnetic carrier particles are spherical particles, the toner concentration T / D (%) satisfies the expression (1), and the toner particles The present invention has been attained by using an electrostatic developer characterized by containing at least a boron-containing organic substance represented by the following general chemical formula. T / D> C eff (1) C eff = 2 · ρt / (2 · ρt + X · ρc) × 100
(%) X = R / r T / D: Toner particle weight content in the developer (%) ρt: true density of toner particles (g / cm ³⁾ rho] c: true density of magnetic carrier particles (g / cm ³ R: Average radius of magnetic carrier particles (μm) r: Average radius of toner particles (μm) General chemical formula

[0008]

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(Wherein R ₁ and R ₄ represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ represent a substituted or unsubstituted aromatic ring (condensed ring) X ⁺ represents a cation.)

Hereinafter, the present invention will be described in detail.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The toner particles used in the present invention are fine powders in which a coloring agent, a boron-containing organic substance as a charge controlling agent, a releasing agent, and other substances as necessary are dispersed in a binder resin. Average particle size of toner is 4-20 μm
Is preferred. As the binder resin used in the present invention, various known resins suitable for toner can be used.
For example, polystyrene, polychlorostyrene, poly-α
-Methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, Styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer and styrene-
Phenyl acrylate copolymer), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate) Styrene-based resins (including styrene or styrene-substituted products) such as copolymers and styrene-phenyl methacrylate copolymers), styrene-α-methyl methyl acrylate copolymer, and styrene-acrylonitrile-acrylate copolymer. Homopolymer or copolymer), vinyl chloride resin, rosin-modified maleic resin, phenol resin, epoxy resin, saturated polyester resin,
Unsaturated polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc. Preferred resins include styrene resins, saturated or unsaturated polyester resins, and epoxy resins.

Among the polyester resins, the crosslinkable polyester resin is composed of a divalent carboxylic acid monomer, a divalent alcohol monomer, a trivalent or higher polyvalent carboxylic acid monomer or a polyhydric alcohol monomer. Obtained by polycondensation of Examples of the dihydric alcohol monomer include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
4-butanediol, neopentyl glycol, 1,4
Diols such as butenediol, bisphenol A,
Examples include etherified bisphenols such as polyoxyethylenated bisphenol A and polyoxypropyleneated bisphenol A, and other dihydric alcohol monomers. As the divalent carboxylic acid monomer, isophthalic acid,
Terephthalic acid, adipic acid, sebacic acid, diphenic acid,
Examples include naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, and anhydrides or lower alkyl esters of these acids as main components. Examples of the trivalent or higher polycarboxylic acid include trimellitic acid, cyclohexanetricarboxylic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, octanetetracarboxylic acid, anhydrides of these acids, and others. As a trihydric or higher polyhydric alcohol monomer,
Trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like.

[0013] Among the styrene resins and polyester resins, those which are non-crosslinkable and have a narrow molecular weight distribution are preferable as the binder resin used for full color which requires gloss and transparency. Polyester resins are more preferred. Weight average molecular weight is 5 of number average molecular weight
It is preferably at most 3 times, more preferably at most 3 times.

The non-crosslinkable polyester resin is obtained by polycondensation containing a divalent carboxylic acid monomer and a divalent alcohol monomer as main components. Examples of the dihydric alcohol monomer and the divalent carboxylic acid monomer include those similar to the crosslinkable polyester resin. The trivalent or higher polyvalent carboxylic acid monomer or polyhydric alcohol monomer may be added to the extent that the properties of the non-crosslinkable resin are not substantially lost, that is, within a range that gives a highly branched structure to the linear polymer. You may add about 2 mol% or less.

Further, the present invention is not limited to the use of one type at a time.
More than one kind of binder resin can be used in combination. The softening point of the developer produced by using the binder resin is preferably 150 ° C. or lower, more preferably 135 ° C. or lower, as measured by a flow tester method. 1
If the temperature exceeds 50 ° C., sufficient low-temperature fixability cannot be obtained,
This is not preferable because the fixing strength tends to deteriorate. The binder resin used for full color which requires gloss and transparency is preferably 125 ° C. or lower, more preferably 115 ° C. or lower. The lower the softening point is, the better the fixing property is, and it is preferable. However, as the softening point is lowered, the glass transition point described later is also lowered.

The glass transition temperature of the developer produced using the binder resin is preferably such that the transition start point (inflection point) as measured by a differential thermal analyzer is 50 ° C. or higher, and 60 ° C. or higher. Are more preferred. When the glass transition temperature is less than 50 ° C., thermal stability during long-term storage is poor,
This causes aggregation and solidification of the toner, which causes a problem in use. 7 more
When the temperature is 5 ° C. or higher, there is a margin in fusing the toner and pulverizing the fine powder, but the softening point increases as the glass transition point increases, so that the fixability tends to deteriorate.

As the colorant used in the present invention, known pigments and dyes may be used. For example, carbon black,
Titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine, navy blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, anthraquinone dye, Coloring agents such as monoazo and disazo dyes and pigments can be used alone or in combination of two or more.

As a colorant for a black toner, carbon black is generally used. Regarding the colorant for full-color toner, C.I. I. Pig
ment yellow 14, C.I. I. Pigmen
t Yellow 17, C.I. I. Pigment Y
yellow 93, C.I. I. PigmentYello
w94, C.I. I. Pigment Yellow 1
38 and the like are known. For magenta, C.I. I.
Pigment Red 48: 1, C.I. I. Pigm
ent Red 53: 1, C.I. I. Pigment
Red 57: 1, C.I. I. Pigment Red 1
22, C.I. I. Pigment Red 123 and the like are known. For cyan, C.I. I. Pigmen
t Blue 15: 3, C.I. I. Pigment B
lue 60 and the like are known. These colorants may be used alone or in combination of two or more. Further, the hue may be adjusted by using a coloring agent such as orange, green, or violet.

The content of the colorant may be sufficient to color the toner so that a visible image can be formed by development. For example, 1 to 20 parts by weight, and especially 3-15 parts by weight are preferred. As the charge control agent used in the present toner,

[0020]

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Wherein R ₁ and R ₄ represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ represent a substituted or unsubstituted aromatic ring (condensed ring) X ⁺ represents a cation.), And an organic substance represented by the general chemical formula is used. Of these organic substances, those that are colorless or light-colored are suitable for use as color toners. Particularly, a boron-containing organic substance represented by the following chemical formula is preferable,

[0022]

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As a commercially available product, LR-147 manufactured by Nippon Carlit Co. is well known and suitable. The amount of the organic substance added is preferably 0.2 to 10% by weight, more preferably 0.4 to 5% by weight in the toner.

Further, it may be used in combination with another charge controlling agent. As other charge control agents, JP-B-3-37183,
Japanese Unexamined Patent Publication No. 2-16916 discloses a gold-containing azo dye, a salicylic acid metal complex described in JP-B-55-42752, a salicylic acid metal salt described in JP-A-63-163374, and the like. A calixarene compound containing no metal element described in Japanese Unexamined Patent Publication No. Hei 5-119535 is mentioned. When used in combination for color, colorless to light-colored ones are preferable, and colorless to light-colored salicylic acid metal complexes, salicylic acid metal salts, and calixarene compounds are known. Commercially available products include Copy Charge NX VP434 manufactured by Hoechst and Pontron E-81, E-84, E-8 manufactured by Orient Chemical Industries.
9 and the like are well known. As a method for incorporating the charge control agent into the toner, there are a method of adding the charge control agent inside the toner and a method of externally adding the charge control agent.

The release agent used in the present invention includes polyalkylene wax, paraffin wax, silicone oil, higher fatty acid, fatty acid amide and the like. The addition amount is 0.05 parts with respect to 100 parts by weight of the binder resin.
-10 parts by weight is preferred. When used in full color applications requiring gloss and transparency, the use of a large amount of these auxiliaries may be harmful. In particular, a toner to which silicone oil has been added is effective not only in the fixing step but also in the developing step. The effect of reducing toner scattering and fog was confirmed.
Considering the characteristics of the silicone oil, the effect of lowering and averaging the adhesive force other than the electrostatic force due to the release effect may produce a preferable effect, but details are not clear.

In the case of a method for producing a toner by a pulverization method, the above-mentioned components may be kneaded with a kneader or the like, cooled, pulverized and classified. An external additive may be added to the toner particles of the present invention. As the external additives, various known inorganic or organic external additives can be used. In particular, in order to improve the fluidity of the toner and suppress aggregation, titania, silica, alumina, zinc oxide, magnesium oxide, etc. Inorganic fine powders are preferred.

In order to improve the flowability of the toner, the external additive has a BET specific surface area of 20 to 700 m ² / g, preferably 5 to 700 m ² / g.
It is preferably about 0 to 500 m ² / g. Specific surface area is 20m ² /
If the amount is less than g, sufficient fluidity cannot be imparted to the toner, so that the screen passing property in the sieving apparatus is deteriorated, and the toner yield is deteriorated (productivity is deteriorated), the transportability during development is deteriorated, and the frictional charging function is deteriorated. There is an invitation problem. In addition, the specific surface area is 700 m ² / g
If it is larger, the partition effect between the toner particles is lost, the storage stability at high temperature is deteriorated, and the external additives are easily aggregated, so that the handleability and uniform dispersion on the toner surface are difficult.

The mixing amount of the external additive varies depending on the average particle diameter and the particle size distribution of the external additive and the toner particles to be used, but it is preferable to obtain the desired toner fluidity, for example, based on 100 parts by weight of the toner particles. 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight. If the mixing amount is less than 0.05 parts by weight, there is no fluidity improving effect and the yield in the sieving apparatus is deteriorated. If the mixing amount is more than 10 parts by weight, filming of the photoreceptor by the partially released external additive is performed. It is not preferable because it is generated or is deposited in the developing tank to cause troubles such as deterioration of the charging function of the developer.

Further, from the viewpoint of stability in a high humidity environment, the external additive is more preferably subjected to hydrophobic treatment with a known treating agent such as silane coupling in the case of inorganic fine powder. In consideration of the properties, dimethyldichlorosilane, monooctyltrichlorosilane, hexamethyldisilazane, silicone oil, etc. may be used as the treating agent for imparting negative charge, and aminosilane, etc. may be used as the treating agent for imparting positive charge. I just need.

In addition, known magnetites, farites, conductive titanium, antimony oxide, tin oxide, cerium oxide, hydrotalcites, etc., other than those for improving fluidity, are used as toner external additives for purposes such as resistance adjustment and abrasives. An appropriate amount of fine powder such as a compound, acrylic beads, silicone beads, and polyethylene beads may be mixed, and the mixing amount is preferably 0.005 to 10 parts by weight based on 100 parts by weight of the toner. When externally adding to the toner particles, the classified toner and the external additive may be stirred and mixed with a high-speed stirrer (such as a Henschel mixer or a super mixer).

As the magnetic carrier particles used in the present invention, conventionally known ones such as iron powder, ferrite powder, magnetite powder, and magnetic resin carrier can be used. Spherical particles that make uniform and soft contact with the photoreceptor during development are preferred, and spherical ferrite powder and spherical magnetite powder are most preferred. As the spherical ferrite powder, the general formula (M
O) _m (Fe ₂ O ₃ ) _n is preferred, and the (MO) component includes CuO, ZnO, Ni
One or more components such as O, FeO, MnO, MgO, BaO, and LiO may be selected and used. Commercially available products include Powdertech F-100, F-150, F-150
L-150 and FSL-100 are the most well-known spherical ferrite powders for electrostatic developing carriers.

The magnetic carrier particles used in the present invention are:
A more preferable effect is exhibited by performing a surface treatment with a resin coating material containing at least conductive fine particles dispersed therein. By adding conductive fine particles, the absolute value of the charge amount becomes lower,
This has the effect of reducing carrier pulling and the effect of improving the color overlay transferability in a full-color development system or the like.
In general, it is said that toner scattering increases when the charge amount is low. However, it was confirmed that toner scattering did not significantly increase when the charge amount was reduced by dispersing and containing conductive fine particles. This is a preferable direction considering stability in continuous printing at a high printing rate. As the conductive fine particles, conductive fine particles such as carbon black, titanium oxide, antimony oxide, tin oxide, zinc oxide, magnetite, maghemite, hematite, and ferrite can be used. It is preferable to exert the effect by adding as little as possible, and those having a low resistivity and a fine particle diameter are more preferable. The resistivity is preferably 10 ⁸ Ω · cm or less, most preferably 10 Ω · cm or less. The primary particle size is preferably 200 nm or less, more preferably 50 nm or less. Therefore,
Carbon black having a low resistivity and a small particle size can be most preferably used. The addition amount depends on the resistivity and the particle size, but is preferably in the range of 25% by weight or less of the coating material.

As the resin coating material used in the present invention, a known silicone resin, acrylic resin, fluorine resin, styrene resin, epoxy resin, polyester resin, polyamide resin, etc., to which an amino group is bonded. Things can be used. The resin may be used alone or may be blended. Alternatively, a resin obtained by coating these resins in a single layer or a multilayer may be used. Particularly, a silicone resin is preferable.

It is more preferable to coat with a coating material containing a resin containing an amino group as the resin coating material. The use of a coating material containing an amino group further reduces toner scattering, and is more preferable due to a synergistic effect with a boron-containing organic substance. As the amino group, 3
Hydrogen, an alkyl group, an allyl group, an aryl group, an aralkyl group or a substituent thereof bonded to a valence nitrogen, such as an unsubstituted amino group —NH ₂ , an alkylamino group, or a dialkylamino group. As the resin containing an amino group, a resin in which an amino group is bonded to a known silicone resin, acrylic resin, fluorine resin, styrene resin, epoxy resin, polyester resin, polyamide resin, or the like can be used. As the coating material containing a resin containing an amino group, a resin containing an amino group alone may be used, and in particular, a known silicone resin containing no amino group, an acrylic resin, a fluorine resin, a styrene resin, an epoxy resin It may be blended with resin, polyester resin, or polyamide resin. Further, at the time of coating, an amino group-containing coupling agent may be added and reacted. In particular, a combination of an amino group-containing resin and a silicone resin, an amino group-modified silicone resin, and a resin to which an aminosilane coupling agent is added when coating the silicone resin are most preferable.

The average particle size of the magnetic carrier particles used in the present invention is not particularly limited as long as it is selected within a range that does not cause “carrier pull” in the developing system to be used.
Those having an average particle diameter of 50 to 200 μm are preferable, and those having an average particle diameter of 90 μm or more are more preferable. The toner concentration T / D (%) of the electrostatic developer used in the present invention is defined by percentage by weight of the toner in the developer. That is, the toner density T / D (%) is calculated by T / D (%) = (weight of toner in developer) / (weight of developer) × 100. The toner concentration T / D (%) of the electrostatic developer used in the present invention is set in a range satisfying the expression (1). T / D> C eff (1) C eff = 2 · ρt / (2 · ρt + X · ρc) × 100
(%) X = R / r T / D: Toner particle weight content in the developer (%) ρt: true density of toner particles (g / cm ³⁾ rho] c: true density of magnetic carrier particles (g / cm ³ R: average radius of magnetic carrier particles (μm) r: average radius of toner particles (μm)

When printing at a high printing rate is continuously performed, if the toner supply cannot keep up with the consumption, the toner density gradually decreases. When used at a toner density T / D lower than the effective toner density C eff, the image quality such as the image density greatly changes due to a decrease in the toner density. When used within a range satisfying the expression (1), the change in image quality is small. Generally, a method using a Coulter counter is widely used for measuring the particle size of toner particles. The average particle size of the toner particles used in the present invention is determined by Coulter Counter TA
The toner particles were dispersed in Isoton using an aperture of 100 μm for Type-II, the toner particle size distribution was measured using channels 3 to 16 and determined by volume averaging. The average radius of the toner particles is の of the average particle size.

The size of the magnetic carrier particles is generally measured using a plurality of sieves having different openings. The sieves with smaller openings are placed one on top of the other with the larger sieve on top, the magnetic carrier particles are sieved, the particle size distribution is determined from the weight of the carrier particles remaining on each sieve, The particle size of the carrier particles is calculated by averaging the mesh size of the sieve and the mesh size of the upper sieve, and calculating the weight average particle size. The average radius of the magnetic carrier particles is defined as 1/2 of this weight average particle size.

The softening point of the binder resin was measured using a flow tester method. Flow tester (C made by Shimadzu Corporation)
FT500), using a nozzle having a diameter of 1 mm and a length of 10 mm, setting the heating body at 80 ° C.
Input. After lightly pressing the plunger and preheating for 300 seconds, a pressure of 30 kg / square cm is applied and the temperature is raised at a rate of 3 ° C./min. The binder resin is softened by the temperature rise, the binder resin is extruded from the nozzle, and the plunger descends. The softening point is the temperature at the midpoint of the plunger's descent distance from the start to the end of the descent.

The glass transition point of the binder resin and the toner particles was determined by using a differential thermal analyzer (DT-30, manufactured by Shimadzu Corporation), charging about 20 mg of the binder resin or the toner particles into the sample cell and setting the same in the measuring section. After heating to 100 ° C. at a rate of temperature rise of 10 ° C./min and cooling to room temperature, the temperature was raised again at 10 ° C./min, and a tangent was drawn from each of the smooth curves before and after the inflection temperature portion of the DTA curve. The intersection of these tangents is taken as the glass transition point. To measure the weight average molecular weight and the number average molecular weight of the binder resin, a known ordinary method is used. For example, an appropriate method in usual gel permeation chromatography is used as follows.

1. Measurement conditions Temperature: 40 ° C. Solvent: tetrahydrofuran Flow rate: 0.5 ml / min. Sample concentration: 0.1% by weight Sample injection volume: 100 μl

2. Column As a column used for appropriately measuring the molecular weight region, a combination of a plurality of commercially available polystyrene gel columns is used. In the measurement of the present invention, GMHXL (30 cm × 2) manufactured by Tosoh Corporation was used.

3. Calibration curve The calibration curve is prepared using standard polystyrene. As standard polystyrene, for example, Pressu
re Chemical Co. Manufactured by Tosoh Corporation or having a molecular weight of 6 × 10 ² , 2.8 × 10 ^2
3 , 6.2 × 10 ³ , 1.03 × 10 ⁴ , 1.67 × 1
^{0 4, 4.39 × 10 4,} 1.02 × 10 5, 1.86
× 10 ⁵ , 2.2 × 10 ⁵ , 7.75 × 10 ⁵ , 1.2
It is appropriate to use 6 × 10 ⁶ and use at least about 10 standard polystyrenes.

4. Detector An RI (refractive index) detector is used as the detector.

[0044]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. Example 1 100 parts by weight of spherical ferrite was coated with about 1 part by weight of a silicone resin to which an aminosilane coupling agent had been added to obtain magnetic carrier particles. The average particle size of the magnetic carrier particles was 105 μm, and the true specific gravity was 4.9 g / cm ³ . 60 parts by weight of a branched polyester resin (constituent monomers: polyoxypropylene bisphenol A, polyoxyethylenated bisphenol A, terephthalic acid, trimellitic acid) Flow tester softening point 114 ° C Glass transition point 67 ° C Volume average molecular weight / number average molecular weight = 2.5) Pigment Pigment Red 122 40 parts by weight was blended and kneaded, crushed, and a magenta pigment pre-kneaded product was procured.

Branched polyester resin (same composition as for pre-kneaded product) 91 parts by weight Magenta pigment pre-kneaded product 15 parts by weight Charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.) 2 parts by weight

[0046]

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The mixture was kneaded, kneaded, pulverized and classified to obtain an unexternally added toner. 100 parts by weight of this non-externally added toner and 0.4 parts by weight of hydrophobic silica (R974, manufactured by Nippon Aerosil Co., Ltd.) were mixed to obtain toner particles (magenta externally added toner).
The volume average particle size of the toner particles is 8.1 μm, and the true specific gravity is 1.
It was 2 g / cm ³ .

A developer having a toner concentration T / D of 4% was obtained by mixing 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles. The effective toner concentration C eff of this developer is 3.64.
%.

The toner particles and the developer were loaded in a machine modified from a commercially available monochrome digital copying machine and the fixing roller portion was removed, and an actual printing test was performed. The printed image was fixed by an external fixing roller coated with silicone oil and evaluated. Stop the machine while printing a blank page,
A scotch mending tape was applied to the position after the development of the OPC photoreceptor and before the transfer, and an attempt was made to collect carrier particles attached to the OPC photoreceptor. That was confirmed.

Printing rate 20% (the white area of the base is
A document with 0% and a black image area of 20%) was set, and 100 sheets of continuous printing were performed, and the maintenance of solid density (followability) and the amount of scattered toner were examined. The maintainability (followability) of the solid density was evaluated by comparing the image densities of the first print image and the 100th print image. The amount of scattered toner was evaluated by comparing the amount of scattered toner accumulated under a developing roller of a developing tank loaded with a developer after printing 100 sheets. The image density was 1.35 on the first sheet and 1.23 on the 100th sheet, and it was confirmed that the image density was stable. The toner scattering was slight but no problem. Next, the paper feeding section of a commercially available monochrome digital copying machine was modified to create a part where the rollers, etc., did not touch the surface of the transfer paper, so that unfixed toner images could be fed only at that position, and the fixing roller was removed. Prepared machine. A simulated test of overlap transfer was performed by loading the developer and copying the same original twice on transfer paper. The print image copied twice was fixed by an external fixing roller coated with silicone oil. The transferred image was formed almost uniformly, and was good even when color superposition development such as full color was assumed.

Example 2 Using the magnetic carrier particles and toner particles obtained in Example 1, 95.5 parts by weight of the magnetic carrier particles and 4.5 parts by weight of the toner particles were mixed as the developer, and the toner concentration T / D4. 5%
Developer was procured. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the solid density maintenance property (following property), the first sheet was 1.47 and the 100th sheet was 1.40, and it was confirmed that the sheet was stable. As in Example 1, toner scattering was slight, but at a level that did not cause any problem. Even in the overlay transfer simulation test, a transfer image was formed almost uniformly as in Example 1, and the results were good even when color overlay development such as full color was assumed.

Comparative Example 1 Using the magnetic carrier particles and toner particles obtained in Example 1, 96.5 parts by weight of the magnetic carrier particles and 3.5 parts by weight of the toner particles were mixed as the developer, and the toner concentration T / D3. 5%
Developer was procured. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the maintainability (followability) of the solid density, it was 1.28 for the first sheet and 1.10 for the 100th sheet, and the image density slightly dropped. The scattering of the toner was better than that of Example 1 and was almost at a level. The simulation test of the superimposition transfer was a transfer image that was slightly less uniform than that of Example 1, and was disadvantageous when color superimposition development such as full color was assumed.

Comparative Example 2 Using the magnetic carrier particles and the toner particles obtained in Example 1, 97 parts by weight of the magnetic carrier particles and 3 parts by weight of the toner particles were mixed, and a developer having a toner concentration T / D of 3% was used. Procured. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, a small amount of carrier particles were collected.
In the evaluation of maintainability (followability) of solid density, the first sheet was 1.21,
The image was 0.98 for the 100th sheet, and the image density of the first sheet was low and the drop in image density was large. Comparative Example 1
Even better. The overlay transfer simulation test was a transfer image with poor uniformity compared to Example 1, and was disadvantageous when color overlay development such as full color was assumed.

Comparative Example 3 Magnetic carrier particles were obtained in the same manner as in Example 1 except that the spherical ferrite had a smaller particle size than that of Example 1. The average particle size of the magnetic carrier particles was 85 μm, and the true specific gravity was 4.9 g / cm ³ . Example 1 of toner particles
The one procured in the above was used. Mixing 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles, the toner concentration T / D 4%
Developer was procured. The effective toner concentration C e of this developer
ff is 4.46%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, a large amount of carrier particles were collected. In the evaluation of the solid density maintenance property (following property), the image density was 1.37 on the first sheet and 1.20 on the 100th sheet. The toner scattering was good as in Comparative Example 2. Even in the overlay transfer simulation test, a transfer image was formed almost uniformly as in Example 1, and the results were good even when color overlay development such as full color was assumed.

Comparative Example 4 The magnetic carrier particles obtained in Example 1 were used. toner
The particles are charged with a charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.).
Bontron E-81 manufactured by Orient Chemical Co., Ltd.
Chromium butylsalicylate complex)
Was procured in the same manner as in Example 1 as described below. Branched polyester resin (used in Example 1) 91 parts by weight Magenta pigment pre-kneaded product (procured in Example 1) 15 parts by weight Charge control agent (Orient Chemical Industries E-81) 2 parts by weight , Kneading, pulverizing and classifying to obtain an unexternally added toner. Real
In the same manner as in Example 1, 100 parts by weight of the non-
0.4 parts by weight of Rica (R974 made by Nippon Aerosil Co., Ltd.)
Mix and procure toner particles (magenta externally added toner)
Was. The volume average particle size of the toner particles is 8.3 μm, and the true specific gravity is
1.2g / cm ^ThreeMet. 96 weight magnetic carrier particles
Parts and 4 parts by weight of toner particles, and the toner concentration T / D4
% Of the developer was procured. Effective toner concentration C of this developer
eff is 3.73%. The same live-action test as in Example 1
went. In the carrier pull evaluation, the carrier particles
Was collected. In the evaluation of solid concentration maintenance (followability)
The first sheet is 1.10 and the 100th sheet is 0.99.
The image density of the 100th sheet was low. Example of toner scattering
As in the case of No. 1, the level was slight but no problem.
In the simulation test of the superimposition transfer, the uniformity was poor as compared with Example 1.
This is a transfer image that is
Was disadvantageous.

Comparative Example 5 The magnetic carrier particles obtained in Example 1 were used. toner
The particles are charged with a charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.).
Hoechst copy charge NX VP434 (grade 4
Example)
1 Procured in the same manner. Branched polyester resin (used in Example 1) 91 parts by weight Magenta pigment pre-kneaded product (produced in Example 1) 15 parts by weight Charge control agent (Copy Charge NX VP434 manufactured by Hoechst) 2 parts by weight The mixture was kneaded, kneaded, pulverized, and classified to obtain an unexternally added toner. Real
In the same manner as in Example 1, 100 parts by weight of the non-
0.4 parts by weight of Rica (R974 made by Nippon Aerosil Co., Ltd.)
Mix and procure toner particles (magenta externally added toner)
Was. The volume average particle size of the toner particles is 8.1 μm, and the true specific gravity is
1.2g / cm ^ThreeMet. 96 weight magnetic carrier particles
Parts and 4 parts by weight of toner particles, and the toner concentration T / D4
% Of the developer was procured. Effective toner concentration C of this developer
eff is 3.64%. The same live-action test as in Example 1
went. In the carrier pulling evaluation, the carrier particles were the same as in Example 1.
Little pups were collected. Solid density maintenance (follow
The evaluation was 1.40 for the first sheet and 1.25 for the 100th sheet.
The image density decrease is slightly larger than in the first embodiment, but is stable.
Was confirmed. A large amount of toner scattering occurred.
The simulation of the overlay transfer was slightly more uniform than in Example 1.
Is a poor transfer image, and is intended for full-color and other color overlay development.
It was disadvantageous if specified.

Example 3 The magnetic carrier particles procured in Example 1 were used. toner
Particles were added except that 0.2 part of silicone oil was added.
Procured in the same manner as in Example 1 as described below. Branched polyester resin (used in Example 1) 91 parts by weight Magenta pigment pre-kneaded product (produced in Example 1) 15 parts by weight Charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.) 2 parts by weight Silicone oil ( 0.2 parts by weight (KF96-500CS manufactured by Shin-Etsu Chemical Co., Ltd.)
And a kinematic viscosity of 500 centistokes. )
The mixture was kneaded, pulverized and classified to obtain an unexternally added toner. Example
1 Similarly, 100 parts by weight of the non-external toner and hydrophobic silica
(R974 manufactured by Nippon Aerosil Co., Ltd.) mixed with 0.4 parts by weight
Then, toner particles (magenta externally added toner) were procured. G
The volume average particle diameter of the toner particles is 8.2 μm, and the true specific gravity is 1.2.
g / cm ^ThreeMet. 96 parts by weight of magnetic carrier particles
4 parts by weight of the toner particles, and the toner concentration T / D 4%
The imaging agent was procured. The effective toner concentration Ceff of this developer is
3.68%. The same live-action test as in Example 1 was performed
Was. In the carrier pulling evaluation, the carrier particles were the same as in Example 1.
Little was collected. Evaluation of solid density maintenance (followability)
The price is 1.40 for the first sheet and 1.27 for the 100th sheet.
It was confirmed that it was set. Example 1 toner scattering
Very good and almost no level. Simulated test of overlay transfer
In this case, the transfer image is formed more uniformly than in Example 1, and
Good even when assuming color overlay development such as color
Met.

Example 4 Magnetic carrier particles were obtained in the same manner as in Example 1 except that carbon black as a conductive agent was dispersed in 5 parts by weight based on 100 parts by weight of the resin in the resin to be coated. The average particle size of the magnetic carrier particles was 105 μm, and the true specific gravity was 4.8 g / cm ³ . The toner particles obtained in Example 3 were used. 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles were mixed to procure a developer having a toner concentration T / D of 4%. Effective toner concentration Ceff of this developer
Is 3.76%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the maintainability (followability) of the solid density, it was 1.45 for the first sheet and 1.36 for the 100th sheet, and it was confirmed that the sheet was stable. As in Example 1, toner scattering was slight, but at a level that did not cause any problem. In the overlay transfer simulation test, the transferred image was formed more uniformly than in Example 1, and was good even when color overlay development such as full color was assumed.

Example 5 As a coating material, 5 parts by weight of carbon black as a conductive agent was dispersed in 100 parts by weight of a silicone resin partially modified with an amino group of -RNHR'NH ₂ (R and R 'are alkylene groups). Use a ferrite containing spherical ferrite 10
0 parts by weight was coated with about 1 part by weight of a coating material to obtain magnetic carrier particles. The average particle size of the magnetic carrier particles is 10
0 μm, and the true specific gravity was 5.0 g / cm ³ . The toner particles obtained in Example 3 were used. 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles were mixed to procure a developer having a toner concentration T / D of 4%. The effective toner concentration Ceff of this developer is 3.79%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the maintainability (followability) of the solid density, 1.37 for the first sheet and 1.100 for the 100th sheet.
25, which was confirmed to be stable. The scattering of the toner was better than that of Example 1 and was almost at a level. Even in the overlay transfer simulation test, a transfer image was formed almost uniformly as in Example 1, and the results were good even when color overlay development such as full color was assumed.

Example 6 As a coating material, 100 parts by weight of a silicone resin partially modified with an amino group of -RNH ₂ (R is an alkylene group) was dispersed and contained 5 parts by weight of carbon black as a conductive agent. A magnetic carrier particle was obtained by coating 100 parts by weight of spherical ferrite with about 1 part by weight of a coating material. The average particle size of the magnetic carrier particles was 105 μm, and the true specific gravity was 4.9 g / cm ³ . Using the non-externally added toner procured in Example 3, the silica was changed to R972 manufactured by Nippon Aerosil Co., Ltd.
The toner particles were externally added in the same manner as in Example 3 except that the amount was changed to 0.5 part by weight. The volume average particle size of the toner particles was 8.2 μm, and the true specific gravity was 1.2 g / cm ³ . 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles were mixed to procure a developer having a toner concentration T / D of 4%. The effective toner concentration Ceff of this developer is 3.68%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. The evaluation of the solid density maintenance (followability) was 1.47 for the first sheet and 1.32 for the 100th sheet. The image density was slightly lower than that in Example 1, but it was confirmed that the image density was stable. As in Example 1, toner scattering was slight, but at a level that did not cause any problem. In the overlay transfer simulation test, the transferred image was formed more uniformly than in Example 1, and was good even when color overlay development such as full color was assumed.

Example 7 The magnetic carrier particles obtained in Example 5 were used. The toner particles are a charge control agent (LR-147 manufactured by Nippon Carlit Co., Ltd.)
Was procured in the same manner as in Example 5, except that the addition amount of was changed from 2 parts by weight to 0.5 parts by weight. The volume average particle size of the toner particles was 8.0 μm, and the true specific gravity was 1.2 g / cm ³ . 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles were mixed to procure a developer having a toner concentration T / D of 4%. The effective toner concentration Ceff of this developer is 3.70%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the maintainability (followability) of the solid density, the result was 1.32 for the first sheet and 1.20 for the 100th sheet, and it was confirmed that the sheet was stable. As in Example 1, toner scattering was slight, but at a level that did not cause any problem. Even in the overlay transfer simulation test, a transfer image was formed almost uniformly as in Example 1, and the results were good even when color overlay development such as full color was assumed.

Example 8 The magnetic carrier particles obtained in Example 5 were used. The toner particles are a charge control agent (LR-147 manufactured by Nippon Carlit Co., Ltd.)
Except that the amount of added was changed from 2 parts by weight to 4 parts by weight.
Procured in the same manner as in Example 5. The volume average particle diameter of the toner particles was 8.4 μm, and the true specific gravity was 1.2 g / cm ³ . 96 parts by weight of magnetic carrier particles and 4 parts by weight of toner particles were mixed to procure a developer having a toner concentration T / D of 4%.
The effective toner concentration Ceff of this developer is 3.88%. The same actual test as in Example 1 was performed. In the carrier pulling evaluation, almost no carrier particles were collected as in Example 1. In the evaluation of the maintenance (followability) of the solid density,
It was 1.33 for the 44th and 100th sheets, and it was confirmed that it was stable. As in Example 1, toner scattering was slight, but at a level that did not cause any problem. In the overlay transfer simulation test, the transferred image was formed more uniformly than in Example 1, and was good even when color overlay development such as full color was assumed.

Example 9 60 parts by weight of a branched polyester resin (used in Example 1), 40 parts by weight of Pigment Yellow 93 were mixed and kneaded, and crushed to obtain a yellow pigment pre-kneaded product. A branched polyester resin (used in Example 1) 60 parts by weight Pigment Blue 15: 3 40 parts by weight was mixed and kneaded, and crushed to obtain a cyan pigment pre-kneaded product. Branched polyester resin (used in Example 1) 91 parts by weight Yellow pigment pre-kneaded product 15 parts by weight Charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.) 2 parts by weight Silicone oil (KF96-500CS manufactured by Shin-Etsu Chemical Co., Ltd.) 0 The mixture was kneaded, kneaded, crushed, and classified in an amount of 0.2 parts by weight to obtain a toner not externally added to yellow. Branched polyester resin (used in Example 1) 93 parts by weight Cyan pigment pre-kneaded product 12 parts by weight Charge control agent (LR147 manufactured by Nippon Carlit Co., Ltd.) 2 parts by weight Silicone oil (KF96-500CS manufactured by Shin-Etsu Chemical Co., Ltd.) 0 The mixture was kneaded, kneaded, pulverized, and classified in an amount of 0.2 parts by weight to obtain a toner not having cyan externally added. In the same manner as in Example 1, 100 parts by weight of the non-externally added toner and 0.4 parts by weight of hydrophobic silica (R974 manufactured by Nippon Aerosil Co., Ltd.) were mixed, and yellow toner particles (yellow externally added toner) and cyan toner particles (cyan). External toner). The volume average particle size of the yellow toner particles is 8.2 μm,
The true specific gravity was 1.2 g / cm ³ . Cyan toner particles have a volume average particle size of 8.1 μm and a true specific gravity of 1.2 g / cm.
^{Was 3} . Magnetic carrier particles 96 procured in Example 4
By weight, 4 parts by weight of these toner particles were mixed to obtain a yellow developer and a cyan developer having a toner concentration T / D of 4%. The effective toner concentration Ceff of the yellow developer is 3.7.
6%. The effective toner concentration Ceff of the cyan developer is 3.71%. For each of the yellow and cyan developers and toner particles, the same carrier pull, solid density maintenance (followability), and toner scattering test were performed as in Example 1. In the carrier pulling evaluation, almost no carrier particles were collected in both yellow and cyan as in Example 1. In the evaluation of the maintainability (followability) of the solid density, yellow was 1.32 for the first sheet and 1.20 for the 100th sheet, and cyan was 1.43 for the first sheet and 1.33 for the 100th sheet. Was confirmed. With respect to toner scattering, yellow was at a level that was better than that of Example 1 and was almost nonexistent. Cyan was at a slight, but no problem, level as in Example 1. In the simulation test of the superimposed transfer, the first copy was performed with a yellow developer according to the test method of Example 1, and the second copy was performed with a cyan developer using an unfixed yellow image. The image was fixed by an external fixing machine. The two color superimposed images were transferred uniformly to form a uniform green image, which was good even when color superimposition development such as full color was assumed.

[0064]

According to the present invention, both toner concentration and chargeability are stabilized while preventing carrier pulling and toner scattering,
It is possible to provide a high-quality electrostatic developer capable of coping with high printing ratio printing.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) G03G 9/10 352 354 (72) Inventor Shinichi Shinichi 1 Fukudacho, Joetsu-shi, Niigata Mitsubishi Chemical Corporation Naoetsu In-house (72) Inventor Toshihiko Aihara 1, Fukuda-cho, Joetsu-shi, Niigata Pref. In Naoetsu, Mitsubishi Chemical Corporation 72) Inventor Kazuo Mitsuhashi 1000, Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa F-term in Yokohama Research Laboratory, Mitsubishi Chemical Corporation 2H005 AA06 BA06 BA07 CA02 CA03 CA07 CA08 CA09 CA11 CA12 CA25 CA28 CB04 DA02 EA05 EA07 EA10

Claims (9)

[Claims] In an electrostatic developer containing at least toner particles and magnetic carrier particles, the magnetic carrier particles are spherical particles, the toner concentration T / D (%) satisfies the formula (1), and the toner particles are An electrostatic developer containing at least a boron-containing organic substance represented by the following general formula. T / D> C eff (1) C eff = 2 · ρt / (2 · ρt + X · ρc) × 100
(%) X = R / r T / D: Toner particle weight content in the developer (%) ρt: true density of toner particles (g / cm ³⁾ rho] c: true density of magnetic carrier particles (g / cm ³ R: Average radius of magnetic carrier particles (μm) r: Average radius of toner particles (μm) General chemical formula (Wherein, R ₁ and R ₄ represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic ring (including a condensed ring), and R ₂ and R ₃ represent a substituted or unsubstituted aromatic ring (including a condensed ring) ) And X ⁺ represents a cation.) 2. The method according to claim 1, wherein the boron-containing organic substance contained in the toner particles is represented by the following chemical formula, and the content of the boron-containing organic substance in the toner particles is 0.4 to 5% by weight. The electrostatic developer according to claim 1, wherein Embedded image 3. The magnetic carrier particles having a volume average particle size of 90 μm.
The electrostatic developer according to claim 1, wherein the electrostatic developer is m or more ferrite particles. 4. The electrostatic developer according to claim 1, wherein the magnetic carrier particles are surface-treated with a resin coating material containing at least conductive fine particles dispersed therein. 5. The electrostatic developer according to claim 4, wherein the magnetic carrier particles are coated with a coating material containing at least a resin containing an amino group. 6. The resin containing an amino group is selected from the group consisting of a silicone resin, an acrylic resin, a fluorine resin, a styrene resin, an epoxy resin, a polyester resin, and a polyamide resin to which an amino group is bonded. The electrostatic developer according to claim 5, wherein the electrostatic developer is a developer. 7. A resin coating material containing an amino group-containing resin, wherein the resin containing an amino group and a silicone resin not containing an amino group, an acrylic resin, a fluorine resin,
The electrostatic developer according to claim 5, which is a mixture with a styrene resin, an epoxy resin, a polyester resin, or a polyamide resin. 8. The electrostatic developer according to claim 5, wherein the resin coating material containing the amino group-containing resin is a silicone resin to which an aminosilane coupling agent is added. 9. A plurality of electrostatic developers containing toner particles of different colors, and electrostatic toner used in multicolor development for visualizing a multicolor image on a transfer material by the toner particles of different colors. 9. The electrostatic developer according to claim 1, which is a developer.