JPH09160304A - Carrier for electrostatic latent image developer, electrostatic latent image developer using that and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a long-life carrier for a developer which can be easily produced and realizes desired charge property even for a coated carrier, to provide a developer with which an image of excellent reproducibility for halftone by using this carrier, and to provide an image forming method using this developer. SOLUTION: This carrier for an electrostatic latent image developer consists of a carrier core and a coating layer comprising a resin and a conductive powder. In this carrier, the average primary particle size (B)μm of the conductive powder and the thickness (A) μm of the resin coating film satisfy the relation of (A)<=(B)<=(A)+3μm. It is preferable that the resin to form the coating layer contains one or more kinds selected from a group of fluorocarbon resin and silicone resin and that the thickness of the resin coating layer is preferably 0.1-10μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carrier for an electrostatic latent image developer used for an electrostatic latent image in an electrophotographic method or an electrostatic recording method, an electrostatic latent image developer using the carrier, and The present invention relates to an image forming method.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, an electrostatic latent image is formed on a photosensitive member or an electrostatic recording member by using various means,
A method of developing an electrostatic latent image by attaching electroconductive fine particles called toner to the electrostatic latent image is generally used.

In this development, carrier particles called carriers are mixed with toner particles and both are triboelectrically charged to give a proper amount of positive or negative electric charge to the toner. Carriers are generally roughly classified into a coated carrier having a coating layer on the surface and a non-coated carrier having no coating layer on the surface. In consideration of the developer life, etc.,
Since the coated carrier is superior, various types of coated carriers have been developed and put into practical use.

Although there are various characteristics required of the coated carrier, it is required to impart appropriate chargeability (charge amount and charge distribution) to the toner and to maintain the proper chargeability of the toner for a long period of time. Impact resistance, wear resistance,
It is particularly important that the chargeability of the toner is not changed even with environmental changes such as humidity and temperature, and various coat carriers have been proposed.

For the purpose of providing a coated carrier having a long service life against such problems, JP-A-61-80161, JP-A-61-80162 and JP-A-61-80163 are used.
In the publication, a resin such as a copolymer of a nitrogen-containing fluorinated alkyl (meth) acrylate and a vinyl-based monomer or a copolymer of a fluorinated alkyl (meth) acrylate and a nitrogen-containing vinyl-based monomer is used as a carrier core material. Techniques for coating the surface have been proposed. According to these, although a carrier having a relatively long life can be obtained, the chargeability of the carrier at the time of development is lowered due to the insulation of the carrier caused by the resin coating, so that the solid effect such as the edge effect is produced particularly in the black solid part. It has drawbacks such as poor reproducibility and a very poor reproducibility when the subject is a halftone image like a photograph.

On the other hand, for the purpose of improving the reproducibility of solids, carriers in which a conductive material is dispersed in a coat film are disclosed in JP-A-1-101560 and JP-A-1-105264.
No. 1993. The electric resistance of such a coated carrier depends on the contact probability between the conductive materials dispersed in the coat film, but it is difficult to control the dispersion of the conductive material in the coat film. Therefore, efficient charging cannot be obtained with respect to the dispersed amount of the conductive material.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the prior art. Therefore, the object of the present invention is to obtain a desired chargeability without increasing the resistance of the developer even in a coated carrier in which the carrier surface is coated with a resin, thus forming an image with excellent halftone reproducibility. Another object of the present invention is to provide a carrier for an electrostatic latent image developer which can be obtained and has a very long life.

Another object of the present invention is to provide a carrier for an electrostatic latent image developer which allows a conductive material in a coat film to act efficiently and can be easily manufactured.

Another object of the present invention is an electrostatic latent image developer which is capable of forming an image having excellent halftone reproducibility using the electrostatic latent image developing carrier having the above characteristics.
Another object of the present invention is to provide an electrostatic latent image developer suitable for use with a color toner containing no charge control agent inside.

Another object of the present invention is to provide an image forming method capable of forming an image having excellent halftone reproducibility by using an electrostatic latent image developer having such excellent characteristics. .

[0011]

DISCLOSURE OF THE INVENTION The inventors of the present invention have diligently studied and studied an electrostatic latent image developing carrier in order to improve the above-mentioned drawbacks in the prior art. Is a carrier for an electrostatic latent image developer having a coating layer comprising a resin and a conductive powder on a carrier core material, and the coating layer is such that the conductive powder is exposed on the surface of the resin coating layer. It was found that the above-mentioned object can be achieved by retaining the inside, and completed the present invention.

That is, the first electrostatic latent image developer carrier of the present invention is an electrostatic latent image developer carrier having a coating layer made of a resin and a conductive powder on a carrier core material. When the average primary particle diameter of the conductive powder is (B) μm and the resin coat thickness is (A) μm, the relationship between the two satisfies the following formula. (A) ≦ (B) ≦ (A) +3 (μm) At this time, the resin coating the carrier may contain at least one kind or two or more kinds selected from the group consisting of a fluororesin and a silicone resin. Preferably, the average particle size of the carrier core material is 10 to 500 μm, and the resin coat thickness is 0.1 to 1
It is preferably 0 μm.

The electrostatic latent image developer of the present invention comprises toner particles composed of a binder resin and a colorant, a carrier having a coating layer composed of a resin and a conductive powder on a carrier core material,
In the electrostatic latent image developer, the average primary particle diameter of the conductive powder is (B) μm, and the resin coat thickness is (A) μm.
Then, the relationship between them satisfies the following equation.

(A) ≦ (B) ≦ (A) +3 (μm) From the viewpoint of the effect of the present invention, it is preferable that the toner particles used in the electrostatic latent image developer are color toner particles. .

In the electrostatic latent image developer of the present invention, the resin constituting the coating layer of the carrier core material is at least one selected from the group consisting of fluorine resin and silicone resin. It is preferable to contain the carrier core material, the average particle diameter of the carrier core material is preferably 10 to 500 μm, and the resin coat thickness is preferably 0.1 to 10 μm.

Further, in the image forming method of the present invention, a step of forming a latent image on the latent image carrier, a step of developing the latent image with a developer, and a developed toner image on the transfer body. In the image forming method including the step of transferring and the step of heating and fixing the toner image on the transfer body, the specific electrostatic latent image developer is used as the developer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The electrostatic latent image developing carrier of the present invention can be applied to a so-called magnetic substance-dispersed carrier in which a magnetic substance is dispersed in a resin, or a resin-coated carrier having a metal powder surface coated with a resin. The effect is effective even if it is used in any one.

Materials for the magnetic material or carrier core material used in the present invention include magnetic metals such as iron, steel, nickel and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. From the viewpoint of using the magnetic brush method for the above, it is desirable to be selected from magnetic metals and magnetic oxides.

When used as a magnetic material for a magnetic material dispersion type carrier, the average particle diameter is generally 0.05 μm to 1
It is about μm, and preferably 0.1 μm to 0.6 μm. The average particle size of the carrier core material is generally 1
Those having a size of 0 μm to 500 μm are used, and preferably 30
Those having a thickness of μm to 150 μm are used.

In the present invention, the conductive powder used is a metal powder of gold, silver, copper or the like, carbon black, a semiconductive oxide such as titanium oxide or zinc oxide,
Examples include powders of titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, etc. whose surface is coated with tin oxide, carbon black, or metal, and whose specific resistance is 10 ¹⁰ Ω · cm or less. preferable.

The average primary particle diameter of these conductive powders is (B) (μm), and the resin coat thickness is (A) (μm).
Then, the relationship between (A) and (B) must satisfy the following formula.

(A) .ltoreq. (B) .ltoreq. (A) +3 (μm) When the above formula is satisfied, the conductive powder contained in the coating layer of the carrier core material is a powder alone coated with an insulating resin. It can be present so as to have a contact with the carrier core and be exposed on the surface of the coating layer of the carrier. From this fact, most of the conductive inorganic powders act as a conductive path in the resin coating film, and further, they can act as a single substance, so that a dispersion technique such as controlling the structure of carbon black is not required so much. Therefore, the amount of conductive powder added to the resin coating film can be reduced,
It is possible to reduce the cost in manufacturing the carrier.

If the average primary particle diameter of the conductive powder is smaller than the resin coat thickness [(A) <(B)], the conductive powder alone cannot act as a conductive path in the resin coat film, and The particle size exceeds the upper limit of the above range [(A)
If +3 (μm) <(B)], the conductive powder is likely to fall off from the carrier surface coating layer, and there is a possibility that image variations occur with an increase in the number of copying, which is not preferable.

The average primary particle size of the conductive powder is 0.1 μm.
It can be appropriately selected depending on the purpose of use (desired charging property) of the carrier within a range of more than m and less than 13 μm and a relationship with the resin coat thickness satisfying the above formula.

As the resin constituting the carrier coating layer, a polyolefin resin (eg polyethylene, polypropylene etc.), polyvinyl and polyvinylidene resin (eg polystyrene etc.), acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol. , Polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone, polyester, polyurethane, polycarbonate, amino resin (for example, urea-formaldehyde resin), epoxy resin, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid Copolymer, linear silicone resin composed of organosiloxane bond and its modified product, fluororesin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinyl Kka vinylidene, polychlorotrifluoroethylene), and the like.

The resin used for the coating layer in the carrier for electrostatic latent image developer of the present invention is not particularly limited, but one or two selected from the group consisting of fluorine resin and silicone resin which are low surface energy materials. It is preferable to contain at least one species from the viewpoint of suppressing contamination of the carrier surface.

As a method of forming the coating layer on the surface of the carrier core material, a method of dispersing the conductive powder in the resin in advance and then coating the core material is applied. Is preferable from the viewpoint of the adhered state of. Examples of the dispersing method include a method of dissolving the coating resin in a solvent, adding a conductive powder, and dispersing by a known mechanical dispersing means such as a sand mill, a ball mill and a homomixer.

The amount of the conductive powder compounded is preferably in the range of 0.01 to 50% by weight of the coating resin,
If it is less than 0.01% by weight, the electrical conductivity will be insufficient and
If the amount exceeds 0% by weight, the adhesive strength will be reduced, which is not preferable.

The method for forming the coating layer on the carrier core material with the coating resin in which the conductive powder is dispersed is not particularly limited, and a known coating method, for example, a powder as the carrier core material is used for forming the coating layer. Immersion method of immersing in the solution, spray method of spraying the coating layer forming solution on the surface of the carrier core material,
A fluidized bed method of spraying a coating layer forming solution in a state where the carrier core material is suspended by fluidized air, a kneader coater method of removing the solvent by mixing the carrier core material and the coating layer forming solution in a kneader coater, etc. Although any of them can be applied, the kneader coater method is particularly preferably used in the present invention. According to this method,
Since the coating is completed while mechanically shearing the carrier powder to be processed, the conductive powder easily holds a contact with the carrier core material.

The solvent used in the coating liquid for forming the coating layer is not particularly limited as long as it dissolves the coating resin, and can be selected so as to be compatible with the coating resin used. Generally, for example, toluene,
Aromatic hydrocarbons such as xylene, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran and dioxane can be used.

The thickness of the resin coat layer formed (resin coat thickness) is usually 0.1 to 10 μm, preferably 0.4.
４4 μm. This resin coat thickness is simply calculated by the following formula, where ρ _{D is} the specific gravity of the carrier core material, _{D is} the average particle diameter of the carrier core material, ρ _C is the specific gravity of the coated resin, and W _C is the total coating amount of the resin. Calculated to.

[0033]

[Equation 1]

From the above formula, by adjusting to a suitable resin coat thickness, it is possible to easily prepare a coated carrier having a good relation between the average primary particle diameter of the conductive powder and the resin coat thickness.

This electrostatic latent image developing carrier exhibits excellent performance in which both suitable conductivity and long life due to resin coating are achieved.

Next, the electrostatic latent image developer of the present invention will be described. The electrostatic latent image developer of the present invention comprises the above electrostatic latent image developing carrier and toner particles composed of a binder resin and a colorant, and is suitable for both black and color. Although it can be used, the effect is remarkable especially in combination with color toner particles.

That is, usually, an external additive is often used in the color toner from the viewpoint of heat retention, but when the external additive comes into contact with the carrier, it moves to the carrier and abrades the coat resin of the carrier, There is a possibility that the charge control force of the resin may be reduced. When the thickness of the resin coat is increased in order to improve the abrasion resistance, it becomes a high resistance carrier, and there is a problem that a low resistance carrier is not suitable for a color developer. The carrier used in the electrostatic latent image developer of the present invention,
The thickness of the resin coat is in a suitable range, and since the inorganic powder, which is a conductive powder, is exposed on the surface of the coating layer, the abrasion resistance is good, and the resistance is low, so it is used in combination with the color toner particles. It has suitable carrier characteristics.

As the colorant for toner particles used in the developer of the present invention, carbon black, nigrosine, aniline blue, calcyl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine. Blue, Malachite Green Oxalate, Lamp Black, Rose Bengal, C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 and the like can be exemplified.

As the binder resin for the toner particles, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene,
Vinyl acetate, vinyl propionate, vinyl benzoate, vinyl acetate and other vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, Α-methylene aliphatic monocarboxylic acid esters such as butyl methacrylate and dodecyl methacrylate, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. Examples thereof include homopolymers and copolymers, and particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, and styrene. - acrylonitrile copolymer, styrene - butadiene copolymer, styrene - maleic anhydride copolymer, polyethylene, polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin,
Paraffin and waxes can also be mentioned as typical binder resins.

Among these binder resins, it is particularly preferable to use polyester as the binder resin. For example, a linear polycondensate containing bisphenol A and a polyvalent aromatic carboxylic acid as main monomer components. Polyester resin can be preferably used.

From the viewpoint of physical properties, the softening point is 90 to 1
50 ° C., glass transition point is 50 to 70 ° C., number average molecular weight is 2,000 to 6,000, and weight average molecular weight is 8,000 to 15,
Resins having a 0000, an acid value of 5 to 30, and a hydroxyl value of 5 to 40 can be particularly preferably used as the binder resin.

The toner particles used in the developer of the present invention may contain known additives such as a charge control agent and a fixing aid, if desired, in addition to the colorant and the binder resin.

The electrostatic latent image developer of the present invention is formed by adding toner particles to the carrier for electrostatic latent image developer of the present invention and coating the surface of the carrier with the toner particles. The amount of particles added is within a known range.

According to the electrostatic latent image developer of the present invention, the chargeability of the carrier at the time of development is not lowered, the solid reproducibility is good, and the subject is in a halftone as in a photograph. Also has the advantage that an image with very good reproducibility can be obtained.

Next, the image forming method of the present invention will be described. The image forming method of the present invention comprises the steps of forming a latent image on a latent image carrier, developing the latent image with a developer, and transferring the developed toner image onto a transfer body.
An image forming method including the step of heating and fixing a toner image on a transfer body, wherein the electrostatic latent image developer of the present invention is used as a developer. For example, the life of the developer is long, the reproducibility of a halftone image is good, and even if the image formation is repeated, the image deterioration can be prevented.

[0046]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Production of Carrier Carrier A Ferrite particles (average particle size: 50 μm) 100 parts by weight Toluene 14 parts by weight Styrene methacrylate copolymer 2.0 parts by weight Aluminum borate coated with tin oxide (average particle size) Diameter: 1 μm) 0.5 parts by weight The above components excluding the ferrite particles that are the carrier core material were dispersed in a sand mill for 10 minutes to prepare a coating layer forming liquid.
Further, this coating layer forming liquid and ferrite particles are put in a vacuum degassing type kneader, stirred at a temperature of 60 ° C. for 10 minutes, and then depressurized to distill off toluene which is a solvent, and boric acid which is a conductive powder. A carrier A was obtained in which a coating layer made of a coating resin in which aluminum was dispersed was formed on a core material.

The film thickness of the resin coat obtained by the calculation was 0.8 μm. (A = 0.8) ≦ (B = 1) ≦ (3.8) (μm) (Example 2) Carrier B Ferrite particles (average particle size; 50 μm) 100 parts by weight Toluene 14 parts by weight Styrene methacrylate copolymer 1.6 parts by weight Perfluoroacrylate copolymer 0.5 parts by weight Barium borate coated with tin oxide (average particle size; 2 μm) 1 part by weight The above components except ferrite particles are dispersed for 10 minutes with a homomixer to form a film. A layer forming liquid is prepared, and the coating layer forming liquid and ferrite particles are put in a vacuum degassing type kneader,
After stirring at a temperature of 60 ° C. for 30 minutes, the toluene was distilled off under reduced pressure, and a coating layer made of a coating resin containing a fluorine-based resin, in which barium borate as a conductive powder was dispersed, was formed on the core material. The formed carrier B was obtained.

The film thickness of the resin coat obtained by calculation was 0.84 μm. (A = 0.84) ≦ (B = 2) ≦ (3.84) (μm) (Comparative Example 1) Carrier C In the preparation of Carrier B of Example 2, barium sulfate coated with tin oxide (average diameter; Carrier C was obtained in the same manner as in Example 2 except that barium sulfate (average diameter; 0.3 μm) coated with tin oxide was used instead of 2 μm).

The film thickness of the resin coat obtained by the calculation was 0.84 μm. (A = 0.84)> (B = 0.3) (μm) (Comparative Example 2) Carrier D In the preparation of Carrier B of Example 2, barium sulfate coated with tin oxide (average diameter: 2 μm) was removed. A carrier D was obtained in the same manner as in Example 2 except for the above.

The film thickness of the resin coat obtained by the calculation is 2
μm. (Comparative Example 3) Carrier E Ferrite particles (average particle size; 50 μm) 100 parts by weight Toluene 14 parts by weight Styrene methacrylate copolymer 0.5 parts by weight The above components except ferrite particles are dispersed for 10 minutes by a sand mill to form a coating layer. A liquid is prepared, and the coating layer forming liquid and ferrite particles are put into a vacuum degassing type kneader and stirred at a temperature of 60 ° C. for 10 minutes, and then toluene is distilled off under reduced pressure to remove the styrene methacrylate copolymer from the copolymer. A carrier E having a coating layer of

The film thickness of the resin coat obtained by the calculation was 0.2 μm. Preparation of Developer 100 parts by weight of each of the carriers of Examples 1 and 2 and Comparative Examples 1 to 3 were mixed with 6 parts by weight of a toner A (magenta toner) having an average particle diameter of 8 μm prepared by the following manufacturing method, and mixed. Different types of developers were prepared. The obtained developers are referred to as developers 1 to 5, respectively. Toner A linear polyester resin 100% by weight (linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4,000, Mw = 35,000, acid value = 12, hydroxyl value = 25) Magenta pigment (CI Pigment Red 57) 3% by weight The above mixture was kneaded with an extruder, pulverized with a jet mill, and then dispersed with a wind classifier to obtain d50 = 8 μm.
Magenta toner particles were obtained. Image formation An electrophotographic copying machine using these developers 1 to 5
(A-Color 630, manufactured by Fuji Xerox Co., Ltd.), the following items were subjected to a copy test.

Initial image: Medium temperature and humidity (22 ° C 55% RH)
The image formed in 1. was visually evaluated to determine the presence or absence of the edge effect.

Toner charge amount after 10 copies: high temperature and high humidity (2
1 copy under each atmosphere of 8 ℃ 85% RH, medium temperature and humidity (22 ℃ 55% RH), low temperature and low humidity (10 ℃ 15% RH).
The toner charge amount (μC / g) after 0 sheets were prepared was measured. The charge amount is a value measured by image analysis of CSG (charge spectrograph method).

Toner charge amount after 10,000 copies: 10,000 copies in an environment of moderate temperature and humidity (22 ° C. 55% RH)
The toner charge amount after the sheet was prepared was measured by the CSG method.

The results are shown in Table 1 below.

[0057]

[Table 1]

As is clear from Table 1, in the case of the developers 1 and 2 using the electrostatic latent image developing carriers of Examples 1 and 2, good images having no edge effect were obtained. The image density measured at this time was stable at 1 to 1.2.

It was also found that the toner charge amount is stable and is not easily affected by the environment regardless of the atmospheric conditions from high temperature and high humidity to low temperature and low humidity. Furthermore, copy 10
It was confirmed that the toner charge amount after 000 sheets was almost the same as that at the initial stage (after 10 copies), showed a stable toner charge amount, and had good durability.

On the other hand, in the case of the developer 3 using the carrier C of Comparative Example 1 in which the conductive powder having a particle diameter smaller than that of the coating film thickness is used, the toner charge amount is low, and the edge is slightly edged. An effective image was obtained. Further, in the case of the developer 4 using the carrier D of Comparative Example 2 which does not contain the conductive powder and has the resin coating layer containing the fluorine-based resin, in particular, the developer is charged under an atmosphere of medium temperature / humidity to low temperature / low humidity. The amount was slightly low, and the edge effect was clearly visible in the obtained image. In the case of the developer 5 using the carrier E of Comparative Example 3 having the resin coating layer containing no conductive powder, an image having no edge effect was initially obtained, but the toner charge amount after 10,000 copies was It was significantly reduced, and it was found that the durability as a developer was lacking.

[0061]

The carrier for an electrostatic latent image developer of the present invention comprises
Because of the above-mentioned constitution, the chargeability of the developer is good, an image having excellent halftone reproducibility can be obtained, and further, even when continuously used for a long time, a good charge imparting ability is maintained. There is. In addition, an electrostatic latent image developer using this carrier for electrostatic latent image developer can obtain an image with excellent halftone reproducibility,
Excellent developer durability. According to the image forming method using the developer of the present invention, an image excellent in halftone reproducibility is obtained.
It can be obtained continuously, and deterioration of the image due to continuous use can be prevented.

Claims (10)

[Claims] 1. A carrier for an electrostatic latent image developer having a coating layer made of a resin and a conductive powder on a carrier core material, wherein the conductive powder has an average primary particle diameter of (B) μm and a resin coat thickness. (A) A carrier for an electrostatic latent image developer, characterized in that the relationship between them satisfies the following expression, where μm is used. (A) ≦ (B) ≦ (A) +3 (μm) 2. The electrostatic latent image developing carrier according to claim 1, wherein the resin contains at least one selected from the group consisting of a fluorine resin and a silicone resin. 3. The average particle diameter of the carrier core material is 10 to 5
The electrostatic latent image developing carrier according to claim 1, wherein the carrier is 00 μm. 4. The resin coat thickness is 0.1 to 10 μm.
2. The carrier for developing an electrostatic latent image according to claim 1, wherein 5. An electrostatic latent image developer comprising toner particles composed of a binder resin and a colorant, and a carrier having a coating layer composed of a resin and a conductive powder on a carrier core material. The electrostatic latent image developer is characterized in that, when the average primary particle diameter is (B) μm and the resin coat thickness is (A) μm, the relationship between the two satisfies the following formula. (A) ≦ (B) ≦ (A) +3 (μm) 6. The electrostatic latent image developer according to claim 5, wherein the toner particles are color toner particles. 7. The resin constituting the coating layer of the carrier core material contains at least one kind or two or more kinds selected from the group consisting of a fluorine resin and a silicone resin. Electrostatic latent image developer. 8. The average particle size of the carrier core material is 10 to 5
The electrostatic latent image developer according to claim 5, having a size of 00 μm. 9. The resin coat thickness is 0.1 to 10 μm.
The electrostatic latent image developer according to claim 5, wherein 10. A step of forming a latent image on a latent image carrier,
An image forming method comprising: a step of developing the latent image with a developer; a step of transferring the developed toner image onto a transfer body; and a step of heating and fixing the toner image on the transfer body. An image forming method, wherein the electrostatic latent image developer according to claim 5 is used as a developer.