JP2000131873A - Toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner having sharp image characteristics small in fog and high in image density and superior in reproducibility and gradation in a highlight part and durability and storage stability by incorporating titanium in fine alumina particles in a specified proportion and controlling a BET specific surface area of these particles in the specified range. SOLUTION: The toner particles contain a binder resin and a colorant and the fine alumina particles containing the titanium in an amount of 10-300 μg/g having a BHT specific surface area of 100-350 m2/g. When the above titanium content exceeds 300 μg/g, the surface activity of the alumina and the aggregation tendency of the particles rises remarkably, thus permitting the BET specific surface area to be remarkably decreased. When the titanium amount drops to <10 μg/g, the reactivity of the fine alumina particles with a surface treating agent not to be sufficiently enhanced and uniformity of the surface treatment of the fine alumina particles to be unsufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a toner for developing an electrostatic image such as electrophotography, electrostatic recording, and electrostatic printing or a toner for forming a toner jet image.

[0002]

2. Description of the Related Art It is well known that an image is formed on the surface of a photoconductive material by electrostatic means and is developed by toner.

More specifically, US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-43 are disclosed.
A number of methods are known, such as US Pat. No. 24,748, and the like. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the toner is called a toner on the latent image. A toner image corresponding to an electrostatic latent image is formed by attaching an extremely finely pulverized inspection material.

Then, if necessary, the toner is transferred onto the surface of an image support such as paper, and then fixed by heating, pressurizing or solvent vapor to obtain a copy. When a step of transferring a toner image is provided, a step for removing the remaining toner is usually provided.

[0005] A developing method for visualizing an electric latent image by using a toner is described in, for example, a powder cloud method described in US Pat. No. 2,221,776, and US Pat. No. 2,618,55.
No. 2,874,063, a magnetic brush method, and a conductive property described in 3,909,258. A method using a magnetic toner is known.

As the toner applied to these developing methods, generally, a colorant-containing resin particle obtained by mixing and dispersing a colorant in a thermoplastic resin and then pulverizing the mixture is used. As the thermoplastic resin, polystyrene resin is the most common, but polyester resin, epoxy resin, acrylic resin,
Urethane resins and the like are also used. As a coloring agent, carbon black is most widely used, and in the case of a magnetic toner, iron oxide black magnetic powder is often used. In the case of a system using a so-called two-component developer, the toner is usually used by being mixed with carrier particles such as glass beads, iron powder, and ferrite powder.

[0007] The toner image on the final copy image forming member such as paper is permanently fixed on the support by heat, pressure or the like. Conventionally, this fixing step has often been performed by heat.

In the case where a step of transferring a toner image is provided, a step for removing residual toner on the photoreceptor is usually provided.

In recent years, the development of monocolor copying to full-color copying in copying machines and the like has been rapidly progressing, and the study and commercialization of two-color copying machines and full-color copying machines have been greatly increased. For example, “Journal of the Society of Electrophotography,” Vol.
22, no. 1 (1983) and "Journal of the Institute of Electrophotography" Vo
l 25, No. 1, P52 (1986).

[0010] However, for those who are not immediately compared with the real thing like televisions, photographs, and color prints, and for those who see a color image processed more beautifully than the real thing, full color electrophotography which is currently in practical use is considered. The images are not always satisfactory.

[0011] Color image formation by full-color electrophotography generally reproduces all colors using three primary color toners of yellow, magenta, and cyan.

In the method, first, an electrostatic latent image is formed on a photoconductive layer by passing light from a document through a color separation light transmitting filter having a complementary color relationship with the color of the toner, and then the toner is developed and transferred. Hold on the support. This process is sequentially performed a plurality of times, and while the registration is being performed, the toner is overlaid on the same support, and the final full-color image is obtained by one-time fixing.

Generally, in the case of a so-called two-component developing system in which a developer is composed of a toner and a carrier, the developer charges the toner to a required charge amount and charge polarity by friction with the carrier, and utilizes electrostatic attraction. Therefore, in order to obtain a good visible image, it is necessary for the toner to have good triboelectric charging properties mainly determined by the relationship with the carrier.

In order to solve the above-mentioned problems, search for a carrier core material and a carrier coating agent and optimization of a coating amount, or study of a charge control agent and a fluidity imparting agent to be added to a toner, and further, a binder as a base material Many studies have been made to achieve excellent triboelectrification in all materials constituting a developer, such as improvement of the developer.

For example, Japanese Patent Publication No. 52-32256 and Japanese Patent Application Laid-Open No. 56-64352 disclose a technique for adding a charge auxiliary agent such as chargeable fine particles to a toner. JP-A-61-160760 discloses that a fluorine-containing compound is added to each developer,
Techniques for obtaining stable triboelectric charging properties have been proposed, and many charging aids have been developed today.

Further, various techniques have been devised as a method for adding the above-mentioned charging aid. For example, a method of attaching the toner particles to the surface of the toner particles by electrostatic force of the toner particles and a charge auxiliary agent or van der Waals force is generally used.
Stirring, a mixer and the like are used. However, in this method, it is not easy to uniformly disperse the additive on the surface of the toner particles, and the presence of the additive which has not adhered to the toner particles and aggregated with each other to form a so-called free state is present. It is difficult to avoid. This tendency becomes more conspicuous as the specific electrical resistance of the charging aid increases and as the particle size decreases. In such a case, the performance of the toner is affected. For example, the amount of triboelectric charge becomes unstable, the image density is not constant, and the image has a lot of fog.

Alternatively, if continuous copying or the like is performed, the content of the charging auxiliary changes, and the image quality in the initial stage cannot be maintained.

As another addition method, there is a method in which a charging auxiliary is added in advance together with a binder resin and a colorant at the time of manufacturing a toner. However, the fact that it is not easy to make the charge control agent uniform, and that it substantially contributes to the chargeability,
Since it is near the surface of the toner particles and the charge auxiliary and charge control agent present inside the particles do not contribute to the charging property, it is not easy to control the amount of the charge auxiliary and the amount of dispersion on the surface. Further, even in the toner obtained by such a method, the amount of triboelectric charge of the toner is unstable, and a toner which satisfies the developer characteristics cannot be easily obtained as described above. The fact is that it is not possible to obtain products of satisfactory quality by itself.

It has been proposed to add an external additive to toner particles to stabilize the triboelectric charging property of the toner. For example, use of hydrophobized alumina is disclosed in Japanese Patent Application Laid-Open Nos. 61-275,862 and 61-275,863.
Has been proposed. These are aluminas whose amino-modified silicone oils are coated on the surface. Aggregation of the alumina particles after the treatment is unavoidable, and it is difficult to impart high fluidity to the toner.

The use of hydrophobically treated alumina is disclosed in JP-A-62-8164 and JP-A-62-12.
9860, JP-A-62-129866, JP-A-62-209538, and JP-A-4-34516.
No. 8, JP-A-4-345169. However, they do not mention at all about the reactivity and crystal structure of alumina particles and a hydrophobizing agent for uniform hydrophobizing treatment, and they are mainly used for stabilizing charging. However, high fluidity is imparted to the toner by using it in combination with silica or the like, and there is a point to be improved in terms of imparting high fluidity and abrasiveness by alumina itself.

Furthermore, Japanese Patent Application Laid-Open No. 251970/1990 also describes alumina as an external lubricating agent having been subjected to a surface treatment with a coupling agent. Problems tend to occur in the charge stabilization under the following conditions, and the addition of fluidity is not satisfactory.

Further, the use of hydrophobized alumina fine powder for the purpose of ensuring fluidity and stabilizing the charge, especially for preventing overcharge at low temperature and low humidity, is disclosed in JP-A-4-280254 and JP-A-4-280254. 280255, JP-A-4-345
No. 169 proposes an alumina fine powder having a degree of hydrophobicity of 40% or more. Certainly, it is effective in stabilizing charging, but it is still required to further improve fluidity compared to fine powders with a high BET specific surface area, such as silica, and uniform treatment has been applied. There is a strong demand for hydrophobized alumina fine powder having a small amount of aggregated particles and maintaining a high BET specific surface area.

Further, Japanese Patent Application Laid-Open No. 3-191363 discloses that
There is a description of a toner containing a hydrophobic γ-crystal alumina polishing substance, but this is intended to ensure that the polishing effect of alumina, which has been conventionally shown, is uniform and effective when a photoconductor made of amorphous silicon is used. It has been studied and has completely different properties from alumina fine powder which simultaneously satisfies the functions of imparting fluidity and stabilizing charge in addition to imparting abrasiveness to the toner.

JP-A-5-34984 discloses a toner containing titanium oxide and alumina, which is an invention for the purpose of stabilizing charging and imparting fluidity and increasing the activity of alumina. For this purpose, the properties are completely different from those of alumina fine particles having titanium oxide.

In recent years, the demand for higher definition and higher image quality of copying machines has been increasing in the market. In the technical field, attempts have been made to achieve higher image quality and color by reducing the particle size of toner. However, as the particle size becomes smaller, the surface area per unit weight increases, and the amount of charge of the toner tends to increase. In addition, since the charge amount of the toner is large, the adhesion between the toners is strong, the fluidity is reduced, and problems arise in the stability of toner replenishment and the application of tribo to the replenished toner.

In the case of a color toner, since it does not contain a conductive substance such as a magnetic material or carbon black, there is no portion where the charge leaks, and the charge amount generally tends to be large. This tendency is more remarkable especially when a polyester binder having high charging performance is used.

Particularly, in the case of color toner, the following properties are strongly desired. (1) In order that the fixed toner does not diffusely reflect light and hinder color reproduction, the toner needs to be in a state of almost complete melting such that the shape of the toner particles cannot be determined. (2) It must be a colored toner having transparency that does not interfere with the toner layers of different colors under the toner layer. (3) Each of the constituent toners must have balanced hue and spectral reflection characteristics and sufficient saturation.

From this point of view, many studies have been made on binder resins, and toners satisfying the above-mentioned characteristics are expected. In the art today, polyester resins are widely used as binder resins for color. However, toners made of polyester resins are generally susceptible to temperature and / or humidity and have an excessive charge amount under low humidity. In addition, there is a problem that the charge amount is insufficient under high humidity, and there is an urgent need to develop a color toner having a stable charge amount even in a wide range of environments.

[0029]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner which solves the above-mentioned problems.

That is, an object of the present invention is to provide clear image characteristics without fog, high image density, fine line reproducibility,
An object of the present invention is to provide a toner which is excellent in gradation of a highlight portion and has excellent durability stability.

A further object of the present invention is to provide a toner which is excellent in fluidity and charge amount uniformity, and excellent in development fidelity and transferability.

A further object of the present invention is to polish and remove deposits on the surface of the photoreceptor and on the surface of the photoreceptor generated by use for a long period of time, or to suppress the generation of the deposits, and to provide a stable image free from image defects. It is to provide a toner which can obtain the following.

A further object of the present invention is to provide a toner which is hardly influenced by the environment such as temperature and humidity and has a stable triboelectric charging property.

It is a further object of the present invention to provide a toner having excellent fixability,
An object of the present invention is to provide a toner having excellent HP permeability.

[0035]

The present invention is directed to a toner having toner particles containing at least a binder resin and a colorant and alumina fine particles, wherein the alumina fine particles contain 10 to 300 μg / g of titanium. And a BET specific surface area of the alumina fine particles of 100 to 350 m ² / g.

The present inventors have sought to improve the above-mentioned conventional problems, in particular, the image density, highlight reproducibility and fine line reproducibility of the formed image, and the durability and environmental stability when outputting a large number of sheets. In particular, intensive studies have been made on the charging stability in a high humidity environment.

As a result, it has been found that by adding a specific amount of titanium having a high activity to the alumina fine particles, the activity of the alumina fine particles can be further enhanced, and the reactivity with the surface treating agent can be improved. It has also been found that since the dispersibility in a solution is also improved, the alumina particles are excellent in uniformity and can be finely divided even after surface treatment.

Further, the toner containing a specific amount of titanium and at least alumina fine particles having a specific BET specific surface area achieves extremely stable environmental characteristics, and has a favorable property even in a highly humid environment. Chargeability is obtained,
It has been found that a toner having extremely good toner fluidity and transferability, having the ability to polish and remove the surface of the photoreceptor and its adhered matter, and having a high ability to suppress the generation of such adhered matter can be obtained. Further, they have found that a high quality and high definition image can be obtained by the toner.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the amount of titanium contained in alumina fine particles is preferably in the range of 10 to 300 μg / g.

The amount of titanium contained in the fine alumina particles is 30.
If it exceeds 0 μg / g, the surface activity of alumina becomes extremely large and the cohesiveness of the particles is increased, so that the particle size becomes extremely large and the BET specific surface area is remarkably reduced. Further, since the positive chargeability of the surface of the alumina fine particles is increased, the charge amount of the toner becomes non-uniform, and the image density becomes uneven. .

On the other hand, when the amount of titanium contained in the alumina fine particles is less than 10 μg / g, the reactivity between the alumina fine particles and the surface treating agent cannot be sufficiently increased, and the surface treatment of the surface of the alumina fine particles cannot be sufficiently increased. Becomes insufficient. Therefore, the toner charge amount distribution is widened,
It is not preferable because fogging and toner scattering occur and the uniformity of image density is reduced, and further, alumina fine particles are released from the surface of the toner particles to cause scratches on the surface of the photoreceptor.

Examples of the titanium compound used in the present invention include those shown in Table 1 below, but are not particularly limited thereto.

[0043]

[Table 1]

Further, in the present invention, as a method of adding the titanium compound, it can be added at the time of forming alumina fine particles or at the time of surface treatment of the alumina fine particles. However, in order to obtain alumina fine particles having more uniform surface properties, It is preferably added during the surface treatment of the alumina fine particles. Further, the titanium compound to be added is preferably wet-pulverized, and the crystal form is preferably amorphous.

The present state of titanium in the present invention may be fixed or adhered to the alumina surface, or may be contained inside the alumina fine particles. From the viewpoint of enhancing the activity of the surface of the alumina fine particles, it is preferable that the particles are fixed.

The BET specific surface area of the alumina fine particles is a physical property indicating the effect on the toner fluidity-imparting ability and environmental stability. BET specific surface area of the alumina particles of the present invention is a 100~350m ² / g, 150~300m ²
/ G.

When the BET specific surface area is less than 100 m ² / g, the particle size of the alumina fine particles is large, indicating the presence of aggregates or coalesced particles, extremely lowering of the toner fluidity, and the surface of the photoreceptor. Damages or deformation of the cleaning means such as a cleaning blade, etc., which are undesirable because they appear as image defects.

When the BET specific surface area is larger than 350 m ² / g, the charging characteristics are adversely affected by humidity, and the toner charging amount is remarkably reduced particularly in a high humidity environment. It is not preferable because it causes problems such as rising, toner scattering and fog.

One of the features of the present invention is to use alumina fine particles. The present inventors have studied the provision of fluidity, chargeability and abrasiveness of the alumina fine particles to the toner. As a result, by reacting the alumina fine particles having high reactivity with the surface treating agent, having a small average particle diameter, and itself having a high polishing effect, with a surface treating agent such as an organic silane compound, or by mixing the alumina fine particles with the silica fine particles. After thoroughly mixing in a solvent, by firing,
It has been found that alumina fine particles having specific physical properties of the present invention and imparting high fluidity, high chargeability and high abrasiveness to the toner can be obtained.

Raw materials for alumina fine particles used in the present invention,
The production method and the like are not particularly limited, but in order to maximize the effects of the present invention, aluminum ammonium carbonate hydroxide is heated at 300 to 1200 ° C.
Amorphous obtained by thermal decomposition at the temperature of
Alternatively, alumina fine particles of γ-crystal or θ-crystal are desirable materials for obtaining the specific properties of the present invention.

Conventionally known α-crystal alumina fine particles have a large average particle diameter and a small BET specific surface area, so that they have extremely low fluidity-imparting ability to toner and cause large scratches on the surface of the photoreceptor. . Furthermore, a sufficient degree of hydrophobicity cannot be obtained due to low reactivity with the surface treating agent, and thus a problem arises in that the charge amount is reduced particularly in a high-humidity environment. In addition, fogging and toner scattering are problematic due to the low charge-imparting ability of the toner.

In addition, conventionally known alumina fine particles of γ crystal have a low fluidity-imparting ability because sufficient fineness has not been achieved. Furthermore, the conventionally known γ-crystal alumina fine particles also have an untreated BET specific surface area, which is lower than that of the γ-crystal alumina fine particles used in the present invention. It is difficult to make the height as high as possible.Because of the presence of aggregates or coalesced particles, sufficient fluidity of the toner cannot be obtained. It causes problems such as deformation. In addition, since the particle size distribution of the alumina fine particles is very wide and uniform charging property to the toner cannot be obtained, image defects such as toner scattering, fogging and image density fluctuation due to durability appear undesirably.

Therefore, conventionally known α-crystal alumina fine particles and conventionally-known γ crystal alumina fine particles are not preferable for the present invention.

In the present invention, the average particle size of the alumina fine particles is from 1 to 1 from the viewpoints of imparting toner fluidity and abrasiveness.
Desirably, it is 00 nm. When the average particle size of the alumina fine particles is smaller than 1 nm, the toner particles are easily embedded in the toner surface, so that the deterioration of the toner occurs at an early stage. It is not preferable because it cannot be done.

On the other hand, the average particle size of the alumina fine particles is 100
When the diameter is larger than nm, not only the fluidity of the toner is remarkably reduced, but also the charging becomes non-uniform.
In addition, the surface of the photoreceptor is seriously damaged, and the damaged part appears as an image defect, or a problem such as deformation and damage of a cleaning member such as a cleaning blade occurs.
Extreme cases are not preferable because they appear as streak-like image defects as poor cleaning.

Further, in the present invention, the degree of hydrophobicity of the alumina fine particles is desirably in the range of 40 to 90%.

When the degree of hydrophobicity is less than 40%, the hydrophobizing treatment is insufficient, and the charge amount is reduced, particularly, the charge amount is remarkably reduced in a high humidity environment, and toner scattering, fog, image quality deterioration, etc. Is a problem. On the other hand, when the degree of hydrophobicity is greater than 90%, it is difficult to control the charging of the alumina fine particles themselves, and as a result, the charge amount of the toner is increased particularly in a low humidity environment. Further, the coalescence of the particles after the hydrophobizing treatment occurs, and the fluidity of the toner is significantly reduced, which is not preferable.

In the present invention, the surface treatment of alumina fine particles with a surface treating agent such as a silane compound includes the following methods, but the present invention is not particularly limited to these methods.

For example, an additive containing a titanium compound in which a titanium compound is mechanically dispersed in a solution is prepared.
After mechanically sufficiently dispersing the alumina fine particles in another solution, the above-mentioned titanium compound-containing additive was dropped,
Further, dispersion and mixing and stirring are performed. Next, a method of adding a surface treatment agent such as a silane compound and hydrolyzing to add a treatment is effective, but the surface treatment method is not particularly limited.

As an example of a surface treatment method by a wet method, first, a predetermined amount of a titanium compound is sufficiently dispersed, mixed and stirred in an aqueous system by a ball mill to prepare an additive. Separately, while mixing and stirring the alumina fine particles in an aqueous system, a predetermined amount of the above-described additive is dropped, and further, the mixing and stirring are performed. Next, a predetermined amount of a surface treatment agent, a diluent thereof or a mixture thereof is added, and the mixture is sufficiently mixed and stirred. Then, a predetermined amount of a surface treatment agent or a diluent thereof or a mixture thereof is further added, and after sufficient mixing and stirring, drying and crushing are performed. Thus, by adding the surface treatment agent stepwise to the alumina fine particles containing the titanium compound, it becomes possible to further increase the reactivity with the surface treatment agent,
Specific physical properties of the present invention can be imparted.

As an example of a surface treatment method by a dry method, a predetermined amount of a surface treatment agent, a diluent thereof, or a mixture thereof is dropped while stirring a predetermined amount of alumina fine particles containing titanium with a device such as a blender. Alternatively, the mixture is added by spraying or the like and sufficiently mixed and stirred. The resulting mixture is then heated and dried. Then, it is crushed by a device such as a pin mill.

Further, the alumina fine particles of the present invention can also be obtained by performing a surface treatment with two or more surface treating agents. For example, nC ₄ H ₉ —Si— (OCH ₃ ) ₃
C ₁₂ H ₂₅ -Si- a (OCH ₃₎ 2 types of coupling agent are mixed surface treatment agent as _3, in a case where a result has a surface treatment, the alumina particles are first small number of carbon atoms The surface treatment agent reacts with the particle surface and the hydroxyl group of the titanium compound present on the particle surface. Next, by reacting the unreacted hydroxyl group with the hydrophobic agent having a large number of carbon atoms, the specific physical properties of the present invention can be imparted to the alumina fine particles.

The surface treating agents used in the present invention include:
Silane-based organic compounds are preferred. The silane-based organic compound may be appropriately selected depending on the purpose of surface modification (for example, control of charging characteristics and further stabilization of charging under high humidity) and the reactivity of the silane-based organic compound. For example, a silane-based organic compound such as an alkoxysilane, an alkylalkoxysilane, a siloxane, a silane, or a silicone oil, which does not itself thermally decompose at the reaction treatment temperature is preferable.

It is particularly preferable to use an alkoxysilane having both a volatile group, a hydrophobic group and a highly reactive bonding group, such as a coupling agent.

Specifically, for example, silane coupling agents include those represented by the general formula R _m SiY _n R: alkoxy group m: an integer of 1 to 3 Y: alkyl group, vinyl group, phenyl group, methacryl group, amino group, epoxy group Group, mercapto group or derivatives thereof n: those represented by an integer of 1 to 3, for example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, methyltrimethoxysilane, methyltrimethoxysilane Ethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane and the like Can be

The amount of the treatment is preferably 1 to 60 parts by weight, more preferably 3 to 50 parts by weight, based on 100 parts by weight of the alumina fine particles.

[0067] Particularly preferred in the present invention is a general formula _{C n H 2n + 1 -Si- (} OC m H 2m + 1) coupling agent represented by ₃ n = _4~12 m = _1~3. Here, if n in the general formula is smaller than 4, the treatment becomes easy, but the degree of hydrophobicity cannot be sufficiently achieved. When n is larger than 12,
Although the hydrophobicity is sufficient, the coalescence of the alumina fine particles increases, and the fluidity-imparting ability decreases. Also, m is 3
If it is larger than the value, the reactivity is lowered and the hydrophobic treatment is not sufficiently performed. Therefore, in the present invention, n is 4 to
12, preferably 4 to 8, m is 1 to 3, preferably 1 to
2 is good.

The amount of the treatment is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, based on 100 parts by weight of the alumina fine particles.

Further, the hydrophobizing treatment may be carried out with a hydrophobizing agent alone, or two or more hydrophobizing agents may be used. For example, one type of coupling agent may be used alone for the hydrophobic treatment, or two types of the coupling agent may be used simultaneously or after performing the hydrophobic treatment using the coupling agent, and then further hydrophobicized using another coupling agent. May be performed. There is no particular limitation on the method of using the hydrophobizing agent and the method of adding the hydrophobizing agent.

In the present invention, the content of the alumina fine particles in the toner is suitably from 0.1 to 5% by weight. When the content is less than 0.1% by weight, it is difficult to obtain high fluidity and sufficient abrasiveness of the toner, and the content is 5% by weight.
If it exceeds, the fluidity of the toner is too high, so that uniform charging is hindered, and not only poor mixing with the replenished toner, but also abrasion becomes high, and the durability of the drum decreases. I do.

Further, the present inventors have studied the stability of image density,
As a result of intensive studies on highlight reproducibility, fine line reproducibility, and environmental stability, it is very effective when the toner containing alumina fine particles having the specific physical properties of the present invention has a weight average particle diameter of 3 to 9 μm. I found

That is, it has been found out that when the alumina fine particles of the present invention are contained and the toner has a weight average particle diameter of 3 to 9 μm, the latent image on the photoreceptor can be developed faithfully.

When the weight average particle diameter of the toner is larger than 9 μm, it means that the number of fine particles that can contribute to the improvement of image quality is basically small, and it is easy to obtain a high image density, and the toner has excellent fluidity. However, it is difficult to adhere faithfully on a fine latent image on a drum, poor in highlight reproducibility, and it is impossible to obtain sufficient resolution. In addition, there is a tendency that development beyond necessity, that is, excessive toner transfer occurs, which tends to increase toner consumption.

Conversely, when the weight average particle diameter of the toner is smaller than 3 μm, it means that the charge amount per unit weight of the toner becomes extremely high, and the density is low, especially the image density is low under low temperature and low humidity. . This is not suitable for applications having a high image area ratio such as graphic images.

When the thickness is smaller than 3 μm, contact charging with the carrier is not performed smoothly, and the amount of toner that cannot be sufficiently charged increases, and scattering to non-image areas, that is, fogging becomes noticeable. To cope with this, it is conceivable to reduce the diameter of the carrier in order to increase the specific surface area of the carrier,
In the case of a toner having a weight average diameter of less than 3 μm, self-aggregation of the toner is apt to occur, and uniform mixing with the carrier is not achieved in a short time, and fog toner tends to be generated in continuous replenishment of the toner.

Therefore, in the present invention, the weight average particle diameter of the toner is preferably 3 to 9 μm.

In order to make full use of the toner having the weight average particle diameter as in the present invention, high fluidity, charge stability and environmental stability of the toner are important points. I can not expect a perfect image.

Therefore, in order to maximize the potential of the toner having the above-mentioned weight average particle diameter and to achieve high resolution and high gradation, high fluidity as in the present invention is required.
It is essential to use alumina fine particles which have high chargeability and polishing properties and are not easily affected by humidity, and a combination of the two can provide a high-definition image with high environmental stability.

Further, the fine particle toner has a small charge per toner and generally tends to be scattered. However, the alumina fine particles of the present invention achieve both improvement of fluidity and stabilization of charging property. can do. This has never been achieved with conventional external additives such as alumina, silica and titanium oxide.

Further, in the present invention, the degree of aggregation of the toner is preferably 2 to 25% (preferably 2 to 20%, more preferably 2 to 15%).

If the degree of aggregation is more than 25%, problems such as a decrease in the transportability of the toner from the toner hopper to the developing device, a poor mixing of the toner and the carrier, and a poor charging of the toner are likely to occur. Therefore, make the toner finer,
Even if the coloring power of the toner is optimized, it is difficult to obtain high quality image quality.

As the binder used in the toner particles according to the present invention, various material resins conventionally known as electrophotographic toner binder resins are used.

For example, styrene-based copolymers such as polystyrene, styrene-butadiene copolymer, styrene-acrylic copolymer, and ethylene-based copolymers such as polyethylene, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer Copolymer, phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, maleic acid resin and the like. In addition, the production method of any resin is not particularly limited.

The effect of the present invention is remarkable when a polyester resin having a high negative charging ability is used among these resins. That is, the polyester-based resin has excellent fixability and is suitable for a color toner, but has a strong negative charging ability and tends to be excessively charged. However, when the polyester resin is used in the composition of the present invention, the harmful effects are improved and excellent. A toner is obtained.

In particular, the following equation

[0086]

Embedded image

(Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and x +
The average value of y is 2-10. A) a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid) Acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) are more preferred because they have sharp melting properties.

The coloring agents used in the present invention include dyes and pigments known as non-magnetic toners such as phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, Benzidine yellow or the like can be used. As its content,
In order to reflect the transparency of the OHP film sensitively, the amount is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin.

Further, the toner of the present invention does not limit the negative charge property and the positive charge property. However, when producing a negative charge toner, a charge control agent is added particularly for the purpose of stabilizing the negative charge property. Is preferred. Examples of the negative charge control agent include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex or an aluminum complex of di-tert-butylsalicylic acid).

When a positively chargeable toner is prepared, nigrosine, a triphenylmethane compound, a rhodamine dye, polyvinyl pyridine or the like may be used as a charge control agent having a positive charge. When a color toner is prepared, it is desirable to use a colorless or light-colored positive charge control agent that does not affect the color tone of the toner.

Additives may be added to the toner of the present invention as needed, as long as the characteristics of the toner are not impaired. Such additives include, for example, charge aids such as organic resin particles and metal oxides, or lubricants such as Teflon, zinc stearate, and polyvinylidene fluoride, or fixing aids (eg, low molecular weight polyethylene, low molecular weight polypropylene). Etc.).

In the production of the colorant-containing resin particles and toner of the present invention, the constituent materials are thoroughly kneaded with a hot kneader such as a hot roll, kneader, extruder, and then mechanically pulverized to classify the pulverized powder. A method of obtaining a toner by dispersing a material such as a colorant in a binder resin solution;
A method obtained by spray drying; a predetermined material is mixed with a polymerizable monomer to form a binder resin to obtain a monomer composition, and an emulsion suspension of the composition is polymerized to form a toner. The resulting toner production method by suspension polymerization can be applied.

When the toner of the present invention is used as a two-component developer, the carrier to be used includes, for example, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and the like, which are not oxidized or surface oxidized. Alloys or oxides and ferrites can be used. In addition, there is no particular limitation on the manufacturing method.

The method of coating the surface of the carrier with a resin or the like includes a method of dissolving or suspending a coating material such as a resin in a solvent, applying the solution, and attaching the solution to the carrier.
Any conventionally known method, such as a method of simply mixing with a powder, can be applied.

The substance to be fixed to the carrier surface varies depending on the toner material. Examples thereof include polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of ditersharry butylsalicylic acid, and styrene-based. It is appropriate to use resin, acrylic resin, polyamide, polyvinyl butyral, nigrosine, aminoacrylate resin, basic dye and its lake, silica fine powder, alumina fine powder, etc. alone or in combination, but it is not necessarily limited to this. Not done.

The amount of the compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but is generally 0.1 to 30% by weight (preferably 0.1 to 30% by weight) based on the total amount of the carrier.
5 to 20% by weight).

The average particle size of these carriers is 10 to 100.
μm, preferably 20-70 μm.

In a preferred embodiment, Cu—Zn—Fe
And the surface of which is a combination of resins such as silicone resin or fluorine resin and styrene resin, for example, polyvinylidene fluoride and styrene-methyl methacrylate resin; polytetrafluoroethylene and styrene-methyl methacrylate resin , A fluorine-based copolymer and a styrene-based copolymer; 90:10 to 20:80, preferably 70:30 to 3
It is a mixture having a ratio of 0:70 and is coated at 0.01 to 5% by weight, preferably 0.1 to 1% by weight.
A coated ferrite carrier having the above average particle diameter of 70% by weight or more of 0 mesh pass, 400 mesh on carrier particles may be used. As the fluorine-based copolymer, a vinylidene fluoride tetrafluoroethylene copolymer (10:90 to 90:10) is exemplified. As the styrene-based copolymer, styrene-2-ethylhexyl acrylate (20:80 to 80) is used. : 20), styrene-2-ethylhexyl acrylate-methyl methacrylate (2
0 to 60: 5 to 30: 10 to 50).

When the coated ferrite carrier has a sharp particle size distribution, favorable triboelectricity is obtained with respect to the toner of the present invention, and the effect of improving electrophotographic properties is obtained.

When a two-component developer is prepared by mixing with the toner of the present invention, the mixing ratio is 2 to 15% by weight, preferably 3 to 13% by weight, as the toner concentration in the developer. More preferably 4% by weight to 10% by weight
In general, good results are obtained. If the toner density is less than 2% by weight, the image density is low and practical use becomes difficult. If the toner density is more than 15% by weight, fog and scattering in the machine are increased, and the useful life of the developer tends to be shortened.

Next, an example of a developing device for developing a non-magnetic one-component toner using the toner of the present invention will be described.
It is not necessarily limited to this. FIG. 1 shows an apparatus for developing an electrostatic image formed on a latent image holding member. In the latent image carrier 1, the latent image is formed by an electrophotographic process unit or an electrostatic recording unit (not shown). The developer carrier 2 is made of a non-magnetic sleeve made of aluminum or stainless steel. The non-magnetic one-component color toner is stored in the hopper 3 and is supplied onto the developer carrier 2 by the supply roller 4. The supply roller 4 also removes the toner on the developer carrier 2 after the development. The toner supplied on the developer carrier 2 is uniformly and thinly applied by the developer application blade 5. The effective contact pressure between the developer application blade 5 and the developer carrier 2 is 3 to 250 g / cm, preferably 10 to 120 g / cm, as the linear pressure in the sleeve generatrix direction. If the contact pressure is less than 3 g / cm, it becomes difficult to apply the toner uniformly, the charge amount distribution of the toner becomes broad, and fog or scattering tends to occur. If the contact pressure exceeds 250 g / cm, a large pressure is applied to the toner, so that the toner is likely to aggregate or be crushed, which is not preferable. By adjusting the contact pressure to 3 to 250 g / cm, it becomes possible to satisfactorily loosen the aggregation of the small particle size toner, and it is possible to instantaneously raise the triboelectric charge of the toner. The developer application blade 5 is preferably made of a material of a triboelectric series suitable for charging the toner to a desired polarity.

In the present invention, silicone rubber, urethane rubber, styrene-butadiene rubber and the like are preferred.
It is preferable to use a conductive rubber because it is possible to prevent the toner from being excessively triboelectrically charged. Further, the surface of the blade 5 may be coated as necessary. In particular, when used as a negative toner, it is preferable to coat a positively chargeable resin such as a polyamide resin.

In a system in which the toner is thinly coated on the developer carrier 2 by the blade 5, the thickness of the toner layer on the developer carrier 2 is adjusted to obtain a sufficient image density. It is preferable that the gap length be smaller than the gap length between the photoconductor and the latent image holding member 1 and an alternating electric field be applied to this gap. By applying a developing bias in which an alternating electric field or a DC electric field is superimposed on the alternating electric field between the developer carrier 2 and the latent image carrier 1 by the bias power source 6 shown in FIG. The movement of the toner on the body 1 is facilitated, and a higher quality image can be obtained.

The method of measuring each characteristic value will be described below.

1. Method for Measuring Titanium Content of Alumina Fine Particles After decomposing an alumina fine particle sample with an acid, qualitative and quantitative analyzes were performed by high frequency inductively coupled plasma emission spectrometry. The SPS-4000 manufactured by Seiko Denshi Kogyo was used as a measuring device.

2. Method for Measuring BET Specific Surface Area of Alumina Fine Particles The BET specific surface area is determined by a BET multipoint method using a fully automatic gas adsorption measuring device: Autosorb 1, manufactured by Yuasa Ionics Co., Ltd., using nitrogen as the adsorbed gas. In addition, as pretreatment of a sample, deaeration is performed at 50 ° C for 10 hours.

3. Measurement method of average particle size of alumina fine particles
The average particle diameter is determined by measuring the particle diameter of 00 particles, the particle diameter on the toner is observed with a scanning electron microscope, and the particle diameter of 300 particles in the visual field is measured to determine the average particle diameter.

4. Method for Measuring Hydrophobicity of Alumina Fine Particles The methanol titration test is an experimental test for confirming the hydrophobicity of an inorganic fine powder having a hydrophobicized surface.

The measurement of the degree of hydrophobicity using methanol for evaluating the degree of hydrophobicity of the alumina fine particles is performed as follows. 0.2 g of the test alumina fine particles are added to 50 ml of water in a 250 ml Erlenmeyer flask. Methanol is titrated from the burette. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The completion of the sedimentation of the alumina fine particles is confirmed by suspending the whole amount in the liquid, and the degree of hydrophobicity is expressed as a percentage of methanol in the liquid mixture of methanol and water when the sedimentation end time is reached.

5. Measuring method of toner particle size distribution As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter)
Is used. As the electrolyte, about 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON
-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, a surfactant (preferably an alkylbenzene sulfonate) is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution, in an amount of 0.1 to 0.1 ml.
Add 5 ml, and add 2 to 20 mg of the measurement sample. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the volume and the number of toner particles were measured for each channel by the measuring device using an aperture of 100 μm as an aperture. Then, the volume distribution and the number distribution of the toner are calculated. Then, the weight average particle diameter (D4) of the toner based on the weight obtained from the volume distribution of the toner particles (the median value of each channel is set as a representative value for each channel) is obtained.

As the channels, 2.00 to 2.52
μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm
m; 4.00 to 5.04 μm; 5.04 to 6.35 μm
m; 6.35 to 8.00 μm; 8.00 to 10.08 μm
m; 10.08 to 12.70 μm; 12.70 to 16.
00 μm; 16.00-20.20 μm; 20.20
25.40 μm; 25.40-32.00 μm;
13 channels of 00 to 40.30 μm are used.

6. Agglomeration Measuring Method The aggregating degree is used as one means for measuring the flow characteristics of a sample (such as a toner having an external additive), and it is determined that the larger the value of the aggregating degree, the poorer the flowability of the sample.

As a measuring device, a powder tester (manufactured by Hosokawa Micron Corporation) having a digital vibrometer (Digi Vibro Model 1332) is used.

As a measuring method, 200-mesh, 100-mesh, and 60-mesh sieves were placed on the shaking table in the order of narrow opening, that is, 200-mesh, 100-mesh, and 60-mesh sieves such that the 60-mesh sieve was at the highest position. Set again.

5 g of the accurately weighed sample was added to the set 60 mesh screen, and the input voltage to the shaking table was reduced to 2 g.
1.7V, the value of the displacement of the digital vibrometer is set to 0.130, and the amplitude of the shaking table at that time is 60 to 90 μm.
m (the rheostat scale is about 2.
5) Apply vibration for about 15 seconds. Thereafter, the weight of the sample remaining on each sieve is measured to obtain the degree of aggregation based on the following equation.

[0116]

(Equation 1)

The sample used was left under an environment of 23 ° C. and 60% RH for about 12 hours.
0% RH.

7. Method for Analyzing Crystal Structure of Alumina Fine Particles X-ray crystal structure analysis is determined by an X-ray diffraction spectrum using Kα line of Cu characteristic X-ray as a source. As the measuring device, for example, a powerful full-automatic X-ray diffractometer MXP ¹⁸ (manufactured by Mac Science) can be used.

When the alumina has a well-defined crystal structure,
That is, in the case of α-type alumina, 2θ is 20
A sharp peak is observed in the range of ~ 70 deg.

[0120]

Embodiments of the present invention will be described below.

(Preparation Example 1 of Alumina Fine Particles) To 3 liters of a 2 M ammonium bicarbonate solution, 2 liters of a 0.2 M ammonium-aluminum bright van solution was added at a liquid temperature of 30
The solution was added dropwise at a rate of 0.8 liters per hour while maintaining the temperature at 0 ° C., and reacted sufficiently with stirring to produce fine powder of aluminum ammonium carbonate hydroxide, which was filtered and dried. The fine powder was heated at 800 ° C. for 24 hours to produce a calcined alumina product. This alumina fired product was pulverized with a speed mill to obtain fine alumina powder. This alumina fine powder has a BET specific surface area of 230 m ² / g,
The average particle size is 6 nm, and the crystal form is γ by X-ray diffraction.
The system was confirmed.

70 parts by weight of toluene and Ti of rutile type crystal
A solution consisting of 30 parts by weight of O _{2 was} prepared and wet-pulverized with a ball mill using alumina balls having a diameter of 5 mm for 100 hours to obtain an additive A. It was confirmed that the crystal form of the titanium oxide component of the additive A was amorphous.

Next, the above-mentioned alumina fine powder was sufficiently wet-pulverized in a ball mill using alumina balls having a diameter of 5 mm in toluene, and the alumina fine powder was dispersed in the solution. after well dispersed adding 5 parts by weight solid content of the additive a described above _{for, i-C 4 H 9 -Si-} (OCH 3) 3 alumina fine powder 100 parts by weight as a surface treatment agent The liquid temperature was kept at 50 ° C., and the mixture was dropped and mixed with sufficient stirring to hydrolyze so that the solid content was 30 parts by weight. Then, after filtering and drying, it was baked at 180 ° C. for 3 hours and crushed. Crushing was performed by a speed mill to obtain alumina fine particles 1.

The physical properties of the alumina fine particles 1 are shown in Table 2.

(Production Example 2 of Alumina Fine Particles) In Production Example 1, 100 parts by weight of alumina fine powder were mixed with TiSi
Alumina fine particles 2 were obtained in the same manner as in Production Example 1 except that 6 parts by weight of an additive containing was added in solid form.

(Production Example 3 of Alumina Fine Particles) Alumina fine particles 3 were obtained in the same manner as in Production Example 1 except that Additive A was added in an amount of 9 parts by weight in solid form.

(Production Example 4 of Alumina Fine Particles) To 3 liters of a 2 M ammonium bicarbonate solution, 2 liters of a 0.2 M ammonium-aluminum bright van solution was added at a liquid temperature of 30 liters.
After dropping at a rate of 0.8 liters per hour while maintaining the temperature at 0 ° C. and causing sufficient reaction with stirring to produce aluminum ammonium carbonate hydroxide fine powder, the amorphous TiO ₂ was solidified into aluminum ammonium carbonate hydroxide. After adding 5 parts by weight to 100 parts by weight per minute and sufficiently dispersing, the mixture was filtered, dried, and further crushed. Here, the pulverization was performed by a speed mill and repeated until the aggregates disappeared, so that the average particle diameter of the fine powder was 35 nm. 1
Heat treatment was performed at 000 ° C. for 24 hours to produce alumina fine powder. This alumina fine powder has a BET specific surface area of 156 m.
² / g, the average particle size was 20 nm, and the crystal form was confirmed to be theta-system by X-ray diffraction.

[0128] Then, after thoroughly wet milling the alumina powder in toluene in a ball mill using alumina balls having a diameter of 5 mm, was dispersed the alumina powder in the solution, C ₆ H as a surface treatment agent ₁₃ -Si- (OCH _{3) 3}
To be 5 parts by weight solid content relative to alumina powder 100 parts by weight, more _{i-C 4 H 9 -Si- (} OC
H ₃ ) ₃ was added dropwise with sufficient stirring while maintaining the liquid temperature at 50 ° C. so that the solid content was 25 parts by weight based on 100 parts by weight of the alumina fine powder, and the mixture was hydrolyzed. Then, after filtering and drying, it was baked at 180 ° C. for 2 hours and crushed. The disintegration was performed by a speed mill, and alumina fine particles 4 were obtained.

(Preparation Example 5 of Alumina Fine Particles) Alumina fine particles 5 were obtained in the same manner as in Preparation Example 2, except that the firing temperature was changed to 750 ° C.

(Production Example 6 of Alumina Fine Particles) Alumina fine particles 6 were prepared in the same manner as in Production Example 1 except that Additive A was added in an amount of 0.5 part by weight based on 100 parts by weight of alumina fine particles. Obtained.

(Production Example 7 of Alumina Fine Particles) Alumina fine particles 7 were obtained in the same manner as in Production Example 1 except that Additive A was added in an amount of 0.3 part by weight of TiO ₂ solid component. Was.

(Production Example 8 of Alumina Fine Particles) Alumina fine particles 8 were obtained in the same manner as in Production Example 1, except that 18 parts by weight of the additive A was added to the fine alumina powder.

(Production Example 9 of Alumina Fine Particles) Production Example 1 was the same as Production Example 1, except that the additive A was not added to the alumina fine powder and the firing temperature was set to 600 ° C.
In the same manner as described above, alumina fine particles 9 were obtained.

(Production Example 10 of Alumina Fine Particles) Production Example 1
In Example 1, alumina fine particles 10 were obtained in the same manner as in Production Example 1 except that Additive A was added in an amount of 4 parts by weight of TiO ₂ solid content and the firing temperature was set to 600 ° C.

(Production Example 11 of Alumina Fine Particles) Production Example 2
In this, alumina fine particles 11 were obtained in the same manner as in Production Example 1, except that 45 parts by weight of iC ₄ H ₉ —Si— (OCH ₃ ) ₃ was added.

(Production Example 12 of Alumina Fine Particles) 100 parts by weight of γ-based alumina powder having a BET specific surface area = 93 m ² / g obtained by hydrolyzing anhydrous aluminum chloride at a high temperature was dispersed in toluene, and a powder having a diameter of 5 mm was obtained. Wet pulverization is performed with a ball mill using alumina balls. Were dispersed in solution, i-C as a surface treatment agent _{4 H 9 -Si- (OCH 3)} 3
Was maintained at 50 ° C., and the mixture was dropped and mixed with sufficient stirring to hydrolyze so that the solid content was 30 parts by weight with respect to 100 parts by weight of alumina powder. Then, after filtering and drying, it was baked at 180 ° C. for 3 hours and crushed. Crushing was performed by a speed mill to obtain alumina fine particles 12.

(Production Example 1 of Titanium Oxide Fine Particles) The BET specific surface area was 101 m ² / g, and the BET specific surface area was determined in the same manner as in the case of the alumina fine particles 12 except that titanium oxide powder of rutile crystal was used. 81 m ² / g of titanium oxide fine particles 1 were obtained.

Example 1 100% by weight of polyester resin obtained by condensing propoxylated bisphenol, fumaric acid, terephthalic acid and trimellitic acid 4 parts by weight of quinacridone pigment 4 parts by weight of chromium complex of di-tert-butylsalicylic acid The mixture was sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, cooled, roughly crushed to about 1 to 2 mm using a hammer mill, and then finely crushed with an air jet pulverizer. Crushed. Further, the obtained finely pulverized product was classified to obtain a negative frictionally chargeable magenta powder.

100 parts by weight of the above colored powder and 1: 1.0 parts by weight of alumina fine particles were mixed with a Henschel mixer to obtain magenta toner 1. The weight average particle size of the magenta toner 1 is 6.2 μm (20.1% is 4.0 μm or less,
53.5% or less is 43.5%, 8.0 μm or more is 6%.
0% and 10.08 μm or more are 0.6%).

A developer was prepared by mixing magenta toner 1 and a silicone resin-coated carrier having an average particle size of 40 μm at a toner concentration of 6%, and a color copier CLC-800 (manufactured by Canon Inc.) was used. Table 3 shows the results of using the original manuscript to produce 20,000 images in a high-temperature, high-humidity environment (32.5 ° C / 90%) and a low-temperature, low-humidity environment (10 ° C / 2.5%). Was.

The developer described above showed extremely small fluctuations in image density, fogging, and toner charge amount in the printing durability test, and showed no problem in scattering of the toner after 20,000 sheets. Thus, excellent results were obtained. The surface of the photoreceptor after 20,000 sheets of durability was observed with a scanning electron microscope. As a result, there was no attached matter or scratch, and the surface condition was good.

Table 3 also shows the results of the following Examples and Comparative Examples.

Example 2 A magenta toner 2 was produced in the same manner as in Example 1 except that the alumina fine particles 2 were used. The same experiment as in Example 1 was carried out. As a result, even after 20,000 sheets of durability, the variation of the toner charge amount was small, the image density was high and stable, and there was no fog and a high-definition image excellent in highlight reproducibility was obtained. And good results were obtained without toner scattering.

Further, no generation of deposits and scratches was observed on the surface of the photoreceptor after the durability test.

Example 3 A magenta toner 3 was produced in the same manner as in Example 1 except that the alumina fine particles 3 were used. In addition, the same experiment as in Example 1 was carried out. As a result, it was found that the fluctuation of the toner charge amount was small, the image density was stable, the fog was small, and no remarkable toner scattering occurred. Was.

Further, no generation of deposits and scratches was observed on the surface of the photoreceptor after the endurance.

Example 4 A magenta toner 4 was produced in the same manner as in Example 1 except that the alumina fine particles 4 were used. When the same experiment as in Example 1 was performed, the uniformity of the toner charge slightly decreased after 20,000 sheets of durability, so that the image density slightly increased, fogging was observed, and a very small amount of toner was observed. Scattering also occurred. However, these phenomena were not at a level that would pose a practical problem.

Further, on the surface of the photoreceptor after the endurance, generation of deposits and flaws which could cause a practical problem was not observed.

Example 5 A magenta toner 5 was produced in the same manner as in Example 1 except that the alumina fine particles 5 were used. When the same experiment as in Example 1 was performed, the uniformity of the toner charge amount slightly decreased after 20,000 sheets of durability, so that the image density slightly increased, fogging was observed, and a small amount of toner scattering was observed. occured. However, these phenomena were not at a level that would pose a practical problem.

Further, on the surface of the photoreceptor after the endurance, generation of deposits and flaws which could cause practical problems was not observed.

Example 6 A magenta toner 6 was produced in the same manner as in Example 1 except that the alumina fine particles 6 were used. When the same experiment as in Example 1 was performed, the uniformity of the toner charge amount slightly decreased after 20,000 sheets of durability, so that the image density slightly increased, fogging was observed, and a small amount of toner scattering was observed. occured. However, these phenomena were not at a level that would pose a practical problem.

Further, on the surface of the photoreceptor after the endurance, generation of deposits and flaws which could cause a practical problem was not observed.

Example 7 The weight average particle diameter obtained in the same manner as in Example 1 was 2.4 μm.
Example 1 except that magenta powder having a negative triboelectric charge of m was used and 2.0 parts by weight of alumina fine particles 1 were added.
When the same experiment as that described above was performed, the image density slightly decreased after 20,000 sheets of durability and fog and toner scattering slightly occurred in both environments, but this was not a level that would cause a problem in practical use.

This is presumably because the toner particle size was small and the charge per unit weight was high, resulting in a slight decrease in image density. Further, it is presumed that the toner is not sufficiently charged because contact charging with the carrier is difficult to be performed smoothly, and slight fog and toner scattering occurred.

Further, on the surface of the photoreceptor after the endurance, no generation of deposits or scratches which could cause a practical problem was observed.

Example 8 The weight average particle diameter obtained in the same manner as in Example 1 was 11.3.
The same experiment as in Example 1 was carried out except that magenta powder having negative frictional charge of μm and 0.5 parts by weight of alumina fine particles 1 were added. Although the density was obtained, the level of reproducibility of the fine line was slightly poor, and the image was slightly lacking in definition. However, it was not at a level that would pose a practical problem.

This is presumably because the toner having a large particle diameter has few particles of 4 μm or less which greatly contribute to the reproducibility of fine lines.

[0158] No adhesion or scratches were found on the surface of the photoreceptor after the durability test.

Comparative Example 1 Comparative toner 1 was produced in the same manner as in Example 1 except that alumina fine particles 7 were used. When the same experiment as in Example 1 was conducted, the uniformity of the toner charge amount was reduced after 20,000 sheets of durability, and toner particles having a very low charge amount were generated. , Toner scattering occurred.

When the surface of the photoreceptor after the endurance was observed, it was found that a large number of scratches, which are thought to be caused by aggregates of alumina fine particles, and that toner adhered were observed.

It is considered that the fine alumina particles 7 used in the present comparative example have low uniformity of the surface treatment, and therefore the uniformity of the toner charge amount is low, thus causing the above-mentioned adverse effects.

Comparative Example 2 Comparative toner 2 was produced in the same manner as in Example 1 except that alumina fine particles 8 were used. In addition, the same experiment as in Example 1 was carried out. As a result, toner particles having low uniformity of toner charge amount and extremely low charge amount were generated after 20,000 sheets of durability, and the image density was remarkably increased. Toner scattering occurred.

When the surface of the photoreceptor after the endurance was observed, it was found that a large number of scratches, which are considered to be caused by aggregates of alumina fine particles, and that toner adhered were observed.

The fine alumina particles 8 used in this comparative example were
Since the titanium content is large, the agglomeration of the alumina fine particles is present in a large amount, so that the particle size distribution is extremely wide. Further, since the titanium content is large, the positive chargeability of the alumina fine particles is high. Therefore, it is considered that the uniformity of the charge amount of the toner is lowered, and the above-mentioned adverse effects are caused.

Comparative Example 3 A comparative toner 3 was produced in the same manner as in Example 1 except that the alumina fine particles 9 were used, and an experiment was conducted. After 20,000 sheets of durability, an increase in image density, fog, and toner scattering occurred. These phenomena occurred remarkably especially in a high humidity environment. This is because the alumina fine particles do not contain titanium, so that the reactivity of the surface treating agent cannot be sufficiently obtained, and further, since the alumina fine particles have a large BET specific surface area, they are affected by humidity and the charge amount is reduced. It is considered to have been caused by doing this.

Further, it was observed that a large number of toners adhered to the entire surface of the photoreceptor after the endurance. This is considered to be because the ability of the alumina fine particles 9 to impart abrasiveness to the toner is low.

Comparative Example 4 A comparative toner 4 was produced in the same manner as in Example 1 except that the alumina fine particles 10 were used, and an experiment was conducted.
After 20,000 sheets of durability, an increase in image density, fog, and toner scattering occurred. These phenomena occurred remarkably especially in a high humidity environment. This is considered to be caused by a decrease in the charge amount due to the influence of humidity due to the large BET specific surface area of the alumina fine particles.

Also, it was observed that a large number of toners adhered to the entire surface of the photoreceptor after the endurance. It is considered that this is because the ability of the alumina fine particles 10 to impart abrasiveness to the toner is low.

Comparative Example 5 A comparative toner 5 was produced in the same manner as in Example 1 except that the alumina fine particles 11 were used. The same experiment as in Example 1 was carried out. As a result, after 20,000 sheets of durability, the toner charge amount was significantly increased, and the charge amount distribution was broadened, so that the image density was reduced, and fog and toner scattering occurred. did.

Further, on the surface of the photoreceptor after the endurance, many deep scratches were observed on the entire surface, and these scratches appeared as image defects.

Alumina fine particles 11 used in this comparative example
Has a low BET specific surface area and contains many aggregates.
When the alumina fine particles are added to the toner, sufficient toner fluidity cannot be obtained, and the aggregates of the alumina fine particles damage the photoreceptor surface. Further, since the degree of hydrophobicity is extremely high, it is difficult to control the toner charge amount. It is considered that these phenomena caused the above phenomenon.

Comparative Example 6 Comparative toner 6 was produced in the same manner as in Example 1, except that 0.5 parts by weight of alumina fine particles 12 and 0.5 parts by weight of titanium oxide fine particles 1 were used. When the same experiment as in Example 1 was performed, an increase in image density, fog, and toner scattering occurred after 10,000 sheets of durability. It is considered that this occurred because the surface treatment of alumina was uneven, and the BET specific surface area of the alumina fine particles and titanium oxide fine particles was low, so that the charge amount was also uneven.

Each evaluation method will be described below.

[0174] evaluation of the fog fog, Tokyo Denshoku made REFRECTOMET
Measured using ER MODEL TC-6DS, using a green filter for magenta toner images,
It was calculated from the following equation. The smaller the value, the less fog.

Fog (reflectance) (%) = reflectance of standard paper (%) − reflectance of non-image portion of sample (%)

A: Fog is less than 1.0%, which is a good level. B: 0.1% or more and less than 2.0%, which is a level having no practical problem. C: 2.0% or more and less than 4.0%, which is a practically problematic level. D: 4.0% or more, which is a practically problematic level.

Observation of the degree of toner contamination around the developing device and the developing device in the main body after 10,000 sheets of toner scattering durability is observed. A: No contamination by toner around the developing device and the developing device in the main body is observed. B: Stain due to a small amount of toner is observed in the developing device. C: Stain due to toner around the developing device and the developing device in the main body is observed. D: The periphery of the developing device and the developing device in the main body is significantly stained by toner, and the function of the main body is adversely affected.

Highlight uniformity An image having a Macbeth image density of 0.3 to 0.6 is output, and the uniformity of density and the degree of roughness are visually evaluated. A: A good output image with excellent image density uniformity. B: Slight lack in uniformity of image density. C: Uniformity of image density is poor, and unevenness of density is observed. D: Uniformity of image density is remarkably poor, and unevenness of density is remarkable.

Photoconductor Surface Condition Thirty places on the photoconductor surface after 20,000 sheets of durability were observed with a scanning electron microscope. A: No deposits such as toner and scratches are observed. B: Attachment such as toner and scratches are observed at several places, but they do not appear as image defects. C: Adhesions such as toner and scratches are observed at more than a dozen locations, and appear as image defects. D: Many deposits and scratches such as toner are observed and appear as remarkable image defects.

[0180]

[Table 2]

[0181]

[Table 3]

[0182]

The toner of the present invention has extremely stable environmental characteristics and high fluidity and transferability, and at the same time has an abrasive property against the surface of the photoreceptor and attached matter, thereby being extremely stable in all environments. High definition and high quality images can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a specific example of a developing device to which the toner of the present invention can be applied.

[Explanation of symbols]

 Reference Signs List 1 latent image holder (photosensitive drum) 2 developer carrier (developing sleeve) 3 hopper 4 supply roller 5 developer coating blade 6 power supply

Claims (5)

[Claims] 1. A toner having toner particles containing at least a binder resin and a colorant and alumina fine particles, wherein the alumina fine particles contain titanium in an amount of 10 to 300 μg /
g, and the BET specific surface area of the alumina fine particles is 100 to
350 m ² / g. 2. An alumina fine particle having an average particle size of 1 to 10
The toner according to claim 1, wherein the thickness is 0 nm. 3. The toner according to claim 1, wherein the alumina fine particles are hydrophobic and have a degree of hydrophobicity of 40 to 90%. 4. The method according to claim 1, wherein the crystal form of the alumina fine particles is amorphous or γ or θ.
4. The toner according to any one of claims 1 to 3. 5. The toner according to claim 1, wherein the weight average particle diameter of the toner is 3 to 9 μm.