JP2893147B2 - Electrophotographic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developer used in electrophotography, electrostatic recording and electrostatic printing.

[0002]

2. Description of the Related Art The development of an electrostatic image has mostly shifted to dry development because of its convenience in handling, but a dry developer is a one-component system comprising a magnetic toner capable of forming a visible image and having magnetic transportability. There is a two-component developer containing a developer and a colored toner that forms a visible image and a magnetic carrier that holds and conveys the toner and that contributes to frictional charging with the toner. Good binary systems are preferred.

[0003] Such a developer is required to have many functional characteristics in terms of developability and fixability, such as electrostatic, thermal or strong physical properties, chemical or fluidity, and blocking of toner. In view of the above, powder properties related to particle size distribution and the like are problematic, and in response to this, various additives for complementing the shape, material and forming method of the toner particles, and complementing the characteristics are used.

Further, in order to ensure the homeostasis of repeated, long-term, continuous development, the selectivity of consumption of constituent particles in a developer,
It must be free from deformation, deterioration, contamination of the photoreceptor and the like and damage, and must have good cleaning properties.

On the other hand, the toner needs to have an appropriate fluidity due to the transportability and chargeability of the particles. For this purpose, inorganic fine particles having a small particle size (average particle size: about 5 to 100 nm) are required. And a method of adding inorganic fine particles having an average particle size of about 0.5 to 5 μm to impart cleaning properties (Japanese Patent Application Laid-Open Nos. 57-174866, 60-136752, and 60-32060).
Or organic fine particles having an average particle size of about 0.05 to 5 μm (JP-A-60-186854, JP-A-60-186859, JP-A-60-18686)
No. 4, No. 60-186866) are known.

[0006] As the number of copies increases, the toner containing the inorganic and organic fine particles externally incorporated therein embeds the fine particles in the toner particles, resulting in a decrease in fluidity and a decrease in image quality due to a decrease in chargeability. I was

To solve these problems, (1) silica is adhered to the toner surface in a partially agglomerated state (Japanese Patent Laid-Open No. 2-289859).

(2) Silica having a primary diameter of 100 nm or less and titania are added (Japanese Patent Publication No. 227664).

(3) Silica having a primary diameter of 1 to 30 nm and 150 nm to
Add 5um of inorganic oxide (Japanese Patent Publication No. 2-45188).

[0010] Each of them has its own drawbacks, and each has its own drawbacks. In the following order: (1) Due to the pressing force applied to the toner in a developing device or the like, the silica aggregates are dispersed to a primary diameter and burial occurs. I do.

(2) The particle size of the two types of additive particles is too small to prevent burial.

(3) The particle size ratio between silica and the inorganic oxide is not appropriate, and the fluidity of the toner is insufficient, or the silica is buried by the inorganic oxide.

[0013] That is, in the external addition treatment of the external additive of fine particles, not limited to the inorganic and organic fine particles of the fluidizing agent, according to the prior art, the external additive is embedded in the toner surface by increasing the copy number (external additive). Burial) phenomenon occurs.

When the external additive is buried, the effects of the external additive, such as fluidity and charge control, are lost, resulting in many problems as an electrophotographic toner.

[0015] Recently, disposal of collected toner has been regarded as an important issue from the viewpoint of environmental protection. To solve this problem, it is preferable to use a copying machine with a toner recycling mechanism that does not generate any waste toner. However, since the recycled toner is more likely to receive stress, the problem of image quality deterioration due to the burying of the external additive is more serious, and the conventional toner cannot withstand recycling.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner which does not cause the external additive to be buried even when the number of copies is increased, and stably provides high quality even when the number of copies is increased.

Still another object is to obtain a highly durable toner compatible with a toner recycling mechanism.

[0018]

The object of the present invention is as follows: an aggregate of silica fine particles (A) adhered to the toner surface, and a particle (B) larger than the average diameter r of the aggregate: specifically, an inorganic particle (C) or The ratio r / R to the average primary particle size R of the organic particles (D) is 1
The problem is solved by an externally added toner prepared in a range of from 1/10 to preferably 1 to 1/6.

In addition, a conventionally known external addition mixer can be used for the external addition treatment for providing this state.

As the type of the particles (B), specifically, (C) and (D), conventionally known types can be used, and a material which satisfies the characteristics required for the intended electrophotographic toner can be selected. The average particle size R is preferably the average toner particle size R.
(T) in the range of 1/1000 to 1/10, more preferably 1
Those having a range of / 500 to 1/10 can provide a better effect.

The procedure of the treatment is, for example, to add a required amount of the silica fine particles (A) to the toner sufficiently mixed with each of the particles (B) so that the average diameter r of the attached aggregates is in a required size range. The mixing process is performed for a short time. However, when particles having good dispersibility are used, it is not necessary to be bound by the above procedure, and a procedure that can easily control the diameter of the adhered aggregate may be adopted.

Regarding the average diameter r of the surface-attached aggregate according to the present invention, an SEM photograph of the toner surface is taken, and the outline of the external additive-attached aggregate is extracted from the photograph by image processing to determine the aggregate diameter. . This operation was performed for 300 aggregates, and the 50% diameter of the distribution was defined as the average diameter r of the attached aggregates.

The main cause of a decrease in toner performance with an increase in the number of copies in the conventional copying process is that the silica fine particles added to the toner are buried in the toner and lose their function.

The burying of the silica fine particles occurs when a pressing force is directly applied to the silica fine particles. Then, it proceeds due to the stirring of the developer in the developing device, the passage of the spike regulating plate portion, and in the case of a copying machine with a toner recycling mechanism, the cleaning portion and the recycled toner conveying portion in addition thereto.

In order to prevent the silica particles from being buried,
It is effective to reduce the pressing force directly applied to the silica fine particles.

As a specific countermeasure, sub-particles having a large contact area with the toner are used together to disperse the pressing force applied to the external additive.

That is, a combination of silica fine particles having a high fluidity-imparting effect and sub-particles having a high burial-preventing effect is used.

However, simply using both of them simply results in
Silica fine particles alone are selectively buried, and the fluidity and charge amount drop sharply, or the silica fine particles do not act at all and sufficient fluidity cannot be obtained, and stable high image quality cannot be obtained .

As a result of intensive studies, it has been found that selecting the particle size of the sub-particles in accordance with the average diameter of the attached aggregates of the silica fine particles prevents not only the sub-particles but also the silica fine particles from being buried, so that even when used for a long time, It is possible to keep the effects of the external additives of both particle sizes at a high level in a well-balanced manner, and as a result, a high-quality output image can be stably obtained.

The average diameter of the aggregates of the adhered silica fine particles r [n
m] Primary particle size of sub-particles R [nm]: (sub-particles
(B): (C), (D), etc.) R> 10r: The acting force of the silica fine particles is smaller than that of the auxiliary particles, and sufficient fluidity cannot be obtained.

R <r: The effect of the sub-particles is so small that burying cannot be prevented. Therefore, the deterioration of the toner fluidity and the charging characteristics as in the related art occurs.

When r / R = 1/1 to 1/10, burying of the external additive can be prevented, and a highly durable toner can be obtained.

As a method for adding the silica fine particles to the surface of the resin fine particles, there is a method in which the toner particles and the silica fine particles are charged into a mixer such as a turbula mixer, a redige mixer, a Henschel mixer, or the like, and stirred.

The degree of the adhesion diameter changes depending on the magnitude of the mechanical energy of the stirring. The mechanical energy can be adjusted by, for example, the peripheral speed of the stirring blade, the stirring time, the quality of the treatment and the like.

The amount of the silica fine particles to be added to the toner particles may be an amount capable of uniformly covering the surface of the toner particles. Specifically, although it varies depending on the particle size and specific gravity of the silica fine particles, 0.1 to 5 parts by weight based on 100 parts by weight
Part by weight is preferred, and 0.5 to 2 parts by weight is particularly preferred. For example, when the addition amount of the silica fine particles is too small, the surface of the toner particles becomes non-uniform, the chargeability changes, and it may be difficult to obtain a desired charge amount. On the other hand, when the addition amount of the silica fine particles is excessive, the amount of the silica fine particles becomes excessive with respect to the surface of the toner particles, and the released silica fine particles are generated. In some cases, it may be difficult to obtain the toner, and further, excessive silica fine particles may adhere to the photoreceptor to cause cleaning failure.

The organic resin particles constituting the sub-particles used in the present invention have an average particle size of 0.05 to 1 from the viewpoints of preventing silica burial and at the same time cleaning and triboelectric charging.
μm, and particularly preferably 0.1 to 0.5 μm. The average particle size of the resin particles is determined by SEM observation.

As the resin material constituting the organic sub-particles,
Various resins are used without any particular limitation. For example, styrene resin such as styrene, α-methylstyrene, divinylbenzene, etc., methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, acrylic resin such as butyl acrylate, styrene, α -A copolymer of a styrene monomer such as methylstyrene and divinylbenzene and an acrylic monomer such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate and butyl acrylate; A styrene-acrylic copolymer,
Examples include a nitrogen-containing resin containing dimethylamino methacrylate, diethylamino methacrylate, and vinylpyridine, a fluorine-containing resin containing Teflon, vinylidene fluoride, and the like, a polyolefin such as polypropylene and polyethylene, a nylon resin, a urethane resin, and a urea resin.

Means for obtaining resin particles composed of the above-mentioned resins include a method of synthesizing a monomer by a polymerization reaction such as emulsion polymerization or suspension polymerization, and a method of melting the resin itself by heat or the like. Examples thereof include a method of atomizing by spraying and a method of dispersing in water or the like to obtain a predetermined particle size. In the case where the resin particles are produced by a polymerization method, a so-called soap-free polymerization method is preferably used so that a surfactant or the like does not remain on the surface of the resin particles in order to stabilize the chargeability. A method of removing the suspension stabilizer may be used.

As the inorganic particles constituting the sub-particles, from the viewpoint of preventing silica burial and improving the cleaning property,
Those having an average particle diameter of 0.05 to 1 μm as a primary average particle diameter are preferable, and those having a primary average particle diameter of 0.1 to 0.5 μm are particularly preferable. In addition, the primary average particle of the inorganic particles refers to a number average particle diameter measured by image analysis observed with a scanning electron microscope.

As the inorganic material constituting the inorganic particles, various inorganic oxides, carbides, nitrides, borides and the like are preferably used. For example, silica, alumina, titania, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, calcium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide , Manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, boron nitride, and the like.

The amount of the sub-particles added to the toner particles is determined based on the viewpoint of enhancing the cleaning property by the polishing effect and not impairing the triboelectric charging property of the toner particles.
It is preferably from 0.01 to 5% by weight, particularly preferably from 0.1 to 2% by weight.

When mixing, it is preferable to use a turbular mixer, Henschel mixer or the like.

The sub-particles may be subjected to a fixing treatment as required.

The toner particles contain a binder resin, a colorant, and other additives such as a charge control agent, if necessary, and have an average particle size of usually 1 to 30 μm. Range.

The charging polarity of the toner particles themselves is determined by the developing method. If necessary, a charge control agent can also be used,
The chargeability of the toner particles can be controlled by the type and amount of the charge control agent, the combination with the resin, and the like. Examples of the charge control agent include salicylic acid derivatives.

Examples of other additives include a fixing property improving agent such as a low molecular weight polyolefin.

When a magnetic toner is obtained, magnetic particles are contained as an additive in the toner particles. As such magnetic particles, particles such as ferrite and magnetite having an average particle diameter of 0.1 to 2 μm are used. The addition amount of the magnetic particles is usually in the range of 20 to 70% by weight of the toner particles.

The developer of the present invention can be used in combination with various conventionally known developing methods.
(1) A magnetic brush of the developer is carried on a developer carrying carrier in a state where the layer thickness is larger than the gap of the developing area, and the magnetic brush is carried into the developing area and the latent image is rubbed by the magnetic brush. A contact-type magnetic brush method in which toner particles or particles in the magnetic brush are attached to a latent image to perform development;
(2) The magnetic brush of the developer is carried on the developer carrying carrier in a state where the layer thickness is smaller than the gap of the developing area, for example, and the magnetic brush is carried into the developing area and the oscillating electric field is applied to the developing area. Accordingly, a developing method such as a non-contact magnetic brush method, in which toner particles or particles are attached to a latent image while flying the toner particles or particles in the magnetic brush to perform development, and (3) a cascade method are used. And can be developed.

The gap between the developing sleeve surface and the photosensitive member surface is
The thickness may be larger or smaller than the thickness of the toner layer. Further, the developing bias may be a DC component only, or an AC bias may be applied simultaneously.

[0050]

Next, the present invention will be described in detail with reference to examples.

First, the reference toner production and the developer will be described as common items.

: Production of toner: 100 parts by weight of polyester resin 10 parts by weight of carbon black 4 parts by weight of low molecular weight polypropylene The above materials were mixed well and kneaded with a kneader set at 130 ° C. After cooling the obtained kneaded material, it was coarsely pulverized by a cutter mill and further finely pulverized by an air-flow crusher. afterwards,
Classification was performed with an air classifier to obtain a toner having a volume average diameter of 8.0 μm.

Preparation of developer: 72 g of toner and styrene
1728 g of a carrier having a spherical ferrite surface coated with a methyl methacrylate copolymer was mixed to prepare a two-component developer.

Example 1 To the obtained toner, 1.0 part by weight of titania fine particles T1 (average primary particle size: 120 nm) was added, and the high-speed stirring type mixer was set at a stirring blade peripheral speed of 40 m / s for 3 minutes. External processing was performed.

Further, 1.0 part by weight of silica fine particles S1 (average primary particle size: 16 nm) was added to the externally added toner, and external addition was performed for 3 minutes with a high-speed stirring mixer in the same manner. The average diameter of the aggregate was adjusted to 50 nm.

U-Bix5070
And a continuous copy was carried out, and a clear image having a very high image density without fogging and covering up to 50,000 copies could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled, and SEM observation was performed. As a result, it was recognized that a large amount of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 2 A two-component developer was obtained in the same manner as in Example 1 except that 2.0 parts by weight of alumina fine particles A1 (average primary particle size 210 nm) were added instead of the titania fine particles T1.

When this developer was mounted on a U-Bix5070 and continuous copying was carried out, a fog up to 50,000 copies was obtained, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled and observed by SEM. As a result, it was found that a large amount of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 3 A two-component developer was obtained in the same manner as in Example 1, except that 2.0 parts by weight of titania fine particles T2 (average primary particle size: 420 nm) was added instead of the titania fine particles T1.

When this developer was mounted on a U-Bix5070 and continuous copying was performed, fog was obtained up to 50,000 copies, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycling pipe was sampled and observed by SEM. As a result, it was found that a large amount of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 4 A two-component developer was obtained in the same manner as in Example 1 except that 2.0 parts by weight of alumina fine particles A1 (average primary particle diameter 210 nm) was added instead of the titania fine particles T4.

When this developer was mounted on a U-Bix5070 and continuous copying was carried out, a fog up to 50,000 copies was obtained, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled and observed by SEM. As a result, it was found that a large number of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 5 Instead of the titania fine particles T1, polymethyl methacrylate (hereinafter referred to as PMMA) fine particles P1 (average primary particle diameter 130 nm) were used.
Performed in the same manner as in Example 1 except that 0.8 part by weight was added.
A component developer was obtained.

When this developer was mounted on a U-Bix5070 and continuous copying was performed, a fog up to 50,000 copies was obtained, and a clear image with very high image density and no spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled, and SEM observation was performed. As a result, it was found that a large number of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 6 A two-component developer was prepared in the same manner as in Example 1 except that 1.6 parts by weight of polystyrene (hereinafter referred to as PSt) fine particles P2 (average primary particle diameter 200 nm) were added in place of the titania fine particles T1. Obtained.

When this developer was mounted on a U-Bix5070 and continuous copying was performed, a fog up to 50,000 copies was obtained, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled and observed by SEM. As a result, it was found that a large number of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Example 7 Instead of the titania fine particles T1, styrene-butyl methacrylate (hereinafter referred to as St-BMA) fine particles P3 (average primary particle size of 45)
0 nm) was obtained in the same manner as in Example 1 except that 1.6 parts by weight of the two-component developer was added.

When this developer was mounted on a U-Bix5070 and continuous copying was performed, a fog up to 50,000 copies was obtained, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled, and SEM observation was performed. As a result, it was recognized that a large number of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared to the initial value.

Example 8 Instead of the titania fine particles T4, PSt fine particles P2 (average primary particle size 2
(00 nm) was added in the same manner as in Example 4 except that 1.6 parts by weight was added to obtain a two-component developer.

When this developer was mounted on a U-Bix5070 and continuous copying was performed, fog was obtained up to 50,000 copies, and a clear image having a very high image density without spots could be obtained all the time.

At the end of 50,000 copies, the toner in the recycle pipe was sampled and observed by SEM. As a result, it was found that a large amount of silica fine particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Comparative Example (1) To the obtained toner, 1.0 part by weight of silica fine particles S1 (average primary particle size: 16 nm) was added, and a high-speed stirring type mixer was set at a stirring blade peripheral speed of 40 m / s to obtain a toner. An external addition treatment was performed for 5 minutes to adjust the average diameter of the aggregates of the adhered silica fine particles to 50 nm.

When the developer composed of this toner was mounted on the U-Bix5070 and continuous copying was performed, the output image density was reduced from 15,000 copies, and the image resolution was also reduced.

At the end of 15,000 copies, the toner in the recycling pipe was sampled and observed by SEM. As a result, almost no silica fine particles were present on the toner surface.

Further, the charge amount of the developer was significantly reduced as compared with the initial value.

Comparative Example (2) To the obtained toner, 1.0 part by weight of titania fine particles T1 (average primary particle size: 50 nm) was added, and a high-speed stirring type mixer was set at a stirring blade peripheral speed of 40 m / s to obtain a toner. An external addition process was performed for minutes.

When the developer consisting of the toner was mounted on the U-Bix5070 and continuous copying was performed, the density of the output image was low from the beginning, and the resolution of the output image was low. In addition, many stains on the non-image portion were observed.

Comparative Example (3) To the obtained toner, 1.0 part by weight of titania fine particles T1 (average primary particle size: 50 nm) was added, and a high-speed stirring type mixer was set at a stirring blade peripheral speed of 40 m / s to obtain a toner. External addition was performed for a minute.

Further, 1.0 part by weight of silica fine particles S1 (average primary particle size: 16 nm) was added to the externally added toner, and external addition was performed for 3 minutes with a high-speed stirring mixer in the same manner. The average diameter of the aggregate was adjusted to 100 nm.

The developer comprising the toner was used in a U-Bix5070
, And continuous copying was performed, the density of the output image was reduced from 20,000 copies, and the resolution of the image was also reduced.

At the end of 20,000 copies, the toner in the recycling pipe was sampled and observed by SEM. As a result, almost no silica fine particles were present on the toner surface.

Further, the charge amount of the developer was significantly reduced compared to the initial stage.

Comparative Example (4) To the obtained toner, 2.0 parts by weight of titania fine particles T2 (average primary particle size: 420 nm) were added, and a high-speed stirring type mixer was set at a stirring blade peripheral speed of 40 m / s. External addition was performed for a minute.

Further, 0.6 parts by weight of silica fine particles S3 (average primary particle size: 7 nm) was added to the externally added toner, and external addition was performed for 3 minutes with a high-speed stirring mixer in the same manner. The average diameter of the aggregate was adjusted to 30 nm.

The developer comprising the toner was supplied to U-Bix5070
, And continuous copying was performed. As a result, the output image density was lower than 12,000 copies, and the image resolution was lower. Thereafter, when the toner in the recycling pipe was taken out and observed, many strong blockings of the toner were observed.

At the end of 12,000 copies, the toner was sampled and observed by SEM. As a result, almost no silica fine particles were present on the toner surface.

Further, the charge amount of the developer was significantly reduced compared to the initial stage.

Comparative Example (5) PMMA fine particles P1 (average primary particle diameter)
50 nm), and the external addition was performed for 3 minutes with the high-speed stirring type mixer set at a stirring blade peripheral speed of 40 m / s.

When the developer composed of this toner was mounted on the U-Bix5070 and continuous copying was performed, the density of the output image was low and the resolution of the output image was low from the beginning. In addition, many stains on the non-image portion were observed.

Comparative Example (6) Instead of titania fine particles T1, PMMA fine particles P1 (average primary particle diameter)
Comparative Example 3 was repeated except that 0.8 parts by weight of 50 nm) was added to obtain a two-component developer.

The developer composed of this toner was used in U-Bix5070
, The density of the output image was lower than that of 18,000 copies, and the resolution of the image was lower.

At the end of 18,000 copies, the toner in the recycle pipe was sampled and observed by SEM. As a result, it was found that many fine silica particles were present on the toner surface.

Further, the charge amount of the developer hardly decreased compared with the initial value.

Comparative Example (7) A two-component developer was obtained in the same manner as in Comparative Example 4, except that 1.6 parts by weight of St-MMA fine particles P3 (average primary particle diameter: 450 nm) was added instead of the titania fine particles T2.

[0110] The developer comprising the toner was used in a U-Bix5070
, And continuous copying was performed, the output image density was reduced from 10,000 copies, and the image resolution was also reduced. Thereafter, when the toner in the recycling pipe was taken out and observed, many strong blockings of the toner were observed.

At the end of 10,000 copies, the toner was sampled and observed by SEM. As a result, almost no silica fine particles were present on the toner surface.

Further, the charge amount of the developer was significantly reduced compared to the initial stage.

Table 1 summarizes the data and characteristics of the above Examples and Comparative Examples.

[0114]

[Table 1]

[0115]

According to the present invention, even when the number of copies increases, the external additive does not bury. Further, even when the toner is recycled, the external additive is not buried.

As a result, good fluidity and stable charging characteristics can be obtained, and a high-quality copy can be obtained for a long period of time.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. A method in which a silica fine particle (A) and a particle (B) having a larger average primary particle size than the silica fine particle (A) are added to the surface of a toner, And the ratio of the average primary particle size R of the fine particles (B) to 1: 1 to 1:10. 2. A toner obtained by adding silica fine particles (A) and inorganic particles (C) having a larger average primary particle size to the surface thereof, the average particle size of the silica fine particles (A) adhered to the toner surface. r, and the ratio of the primary particle size R of the inorganic particles (C) to 1: 1 to 1/10. 3. An average particle diameter of the silica fine particles (A) attached to the toner surface of a toner in which silica fine particles (A) and organic particles (D) having a larger average primary particle diameter are added to the surface. r, the ratio of the primary particle size R of the organic particles (D) to 1: 1 to 1/10.