JPH0627724A - Positively charged one-component developer - Google Patents

Abstract

PURPOSE:To provide a positively charged one-component developer with stable fixing properties and excellent offset resistance and stress resistance by using a specific crosslinked polymer as binding resin, providing a quaternary ammonium salt as a charge control agent by a specific amount, and adding a specific fluidizer. CONSTITUTION:A positively charged one-component developer comprises binding resin, colorant, a charge control agent and a fluidizer. The binding resin is a copolymer of formulae I-III, i.e., a crosslinked polymer with melt viscosity at 130 deg.C and 160 deg.C being 1X10<5> to 1X10<7> poise and 1X10<4> to 1X10<6> poise, respectively; the charge control agent is composed of a quaternary ammonium salt and is contained in the developer by 0.05 to 5.0wt%; the fluidizer is prepared by addition of positively charged silica and negatively charged silica in the ratio of 9:1 to 5:5 to the developer by 0.01 to 3.0wt.%. In the formulae, R1 represents H, CH3, R2 represents H, a C1-10 alkyl group, R3 represents CnH2n (n is l to 5), and R4 represents a C1-5 alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electronic printing,
The present invention relates to a one-component developer used for electrostatic recording and the like.

[0002]

2. Description of the Related Art Conventionally, US Pat.
297691 specification, Japanese Patent Publication No. 42-23910,
Also, various methods are described in Japanese Examined Patent Publication No. 43-24748 and the like. Generally, a photoconductive substance is used to form an electric latent electrostatic image on a photoconductor by various optical means, and then the latent electrostatic image is visualized by using a developer (hereinafter referred to as toner). If necessary, it is transferred onto paper or the like and then fixed by heating or pressure to obtain a copy image.

As a method of visualizing an electric latent image by using a toner, a magnetic brush method described in US Pat. No. 2,870,633 and a cascade developing method described in US Pat. No. 2,618,552 are disclosed. And U.S. Pat. No. 290
Various methods such as a method using a conductive magnetic toner described in the specification of 9258 are known.

The developing method is mainly a two-component developing method in which iron powder called carrier, a mixture of glass bead particles and the like and a toner are used as a developer, and a one-component developing method in which the toner alone is used as a developer. There is a method.
The toners used in these are required to have various physical and chemical properties.

The former two-component developing method is a developing method in which the toner and the carrier are mixed and stirred, and the toner is charged by mutual frictional charging, so that the charging property and the transporting property are stable. However, this method consumes toner one after another, so it is necessary to keep the ratio of toner and carrier constant.
The toner density adjustment function is required, and it is difficult to reduce the size and weight.

In the latter one-component developing method which enables downsizing and weight reduction, a magnetic one-component developing method for conveying toner by utilizing magnetic force has been devised. In addition, a non-magnetic one-component developing method has been devised, in which the one-component developer is charged, conveyed, and supplied only by the developer-carrying roller member, which can be made smaller and lighter than a magnet roller. In particular, since it does not use magnetism, it is used for color development in some cases.

As is well known, the toner for electrostatic charge development used in these developing methods is generally composed of a resin component, a coloring component composed of a pigment or a dye, and an additive component such as a plasticizer and a charge control agent. ing. As the resin component, natural or synthetic resins are used alone or in a proper mixture.

However, as the tendency toward higher image quality of copied images and long-term stability of image quality has become remarkable in recent years, the binder resin, which is a main constituent component of the toner, has a fixing property higher than that of conventional toners and durability. Is required. JP-B-51-23354, JP-B-63-39052, JP-B-63-42252, JP-B-63-49221
Japanese Patent Publication, Japanese Patent Publication No. 63-52375, Japanese Patent Publication No. 1-1
Japanese Patent No. 7579 proposes a toner using a cross-linked polymer as a binder resin, and provides a toner having excellent fixability and impact resistance and excellent durability. Further, Japanese Patent Application Laid-Open No. 54-143647 proposes an electrophotographic toner containing an amino group containing no additive, and provides a toner having stable charging characteristics.

[0009]

However, the above configuration has the following problems.

Many toners that are easily melted by heating are likely to be caked or aggregated during storage or in the developing unit of a copying machine. Also, with many toners, due to repeated development due to long-term continuous use, the toner particles collide with members in the developing device and are impacted by stress from the layer regulation member, etc., and the toner particles deteriorate, resulting in image density Or the background density is increased, and the quality of the copied image is deteriorated.

These undesired phenomena are often due to the brittleness of toner particles. That is, it relates to the life of the developer. In particular, the toner particles in the developing device are transported to the developing area facing the electrostatic latent image by the developer carrying roller member, layer regulating blade, developing roller, etc. Receive a lot of stress from. This stress causes the toner
The particles are destroyed and the number of fine powder particles is increased, or the hydrophobic silica particles externally treated on the resin surface are driven into the resin, so that the toner particles are deteriorated and the developing characteristics are deteriorated. In order to avoid such a deterioration phenomenon, it has been proposed to use the above-mentioned crosslinkable high molecular weight polymer. However, if the crosslinking temperature is simply crosslinked, the fixing temperature is increased in the heat fixing step which is the final step of copying. Rise and need more heat. Further, in a crosslinked high-viscosity type polymer, when the pigment is kneaded and dispersed in the resin, it is difficult to sufficiently disperse the pigment sufficiently. Therefore, a toner using the crosslinked polymer as a binder resin obtains good developing characteristics. It has the drawback of being difficult. On the other hand, attempts have been made to improve these problems by mixing a cross-linked polymer with another resin, but this alone cannot provide sufficient dispersibility. This is because a high-viscosity resin such as a crosslinked polymer impedes the wettability between the resin and an internal additive such as a pigment during kneading.

When the internal additives such as pigments are poorly dispersed, particles having good dispersion are used for development during long-term use, and particles having poor dispersion remain in the developing device for selective development, which is a toner property. Cause deterioration.

Further, in the one-component development in which the chargeability is important in the above-mentioned constitution, the negative chargeability tends to become strong in the above-mentioned constituent materials, and a sufficient charge amount cannot be obtained for the positively-charged one-component development. There is a situation. Therefore, a method of increasing the positive chargeability by increasing the addition amount of the positive charge control agent is used, but with this, the dispersibility of the internal additive such as the charge control agent is deteriorated, the charge distribution becomes broad, and the developing characteristics are It becomes a factor to worsen.

Further, in order to improve the fluidity of the toner, fine powder such as silica is externally added in the final step. Many silicas used at this time are hydrophobized with hexamethylenedisilazane, dimethyldichlorosilane and the like. These show good characteristics for enhancing the fluidity of the toner, but have negative chargeability. It tends to appear strongly and is not suitable for positively charged toner. In addition, positively-charged silica treated with aminosilane or the like easily aggregates, has difficulty in moisture resistance, and has a problem in one-component development that requires high fluidity.

In view of the above problems, the present invention is excellent in stable fixing property, anti-offset property and stress resistance, does not cause agglomeration and is excellent in fluidity, and has good internal additives such as pigments. The present invention aims to provide a stable positively charged one-component developer which can be dispersed in a high-charged state, can obtain a high-charged positive charge even in the positively-charged one-component development, has stable developability, has a high image density, and has no fog. .

[0016]

In order to achieve this object, the present invention uses a crosslinked polymer having a strong stress resistance, and a monomer having a functional group having a strong positive charging property is copolymerized therewith. Further, a quaternary ammonium salt is added in order to improve the rise of charging. Furthermore, a mixture of positively charged hydrophobic silica and negatively charged hydrophobic silica is externally added. With this configuration, it becomes possible to simultaneously satisfy positive charging property, fixing property, fluidity and stress resistance.

That is, the positively charged one-component developer of the present invention is an electrostatic latent image carrier for carrying an electrostatic latent image, a developer hopper for containing the developer, and the developer is frictionally charged. Used in a developing device including a developer carrying roller member for carrying and carrying the developer, a developing roller for carrying the developer to a developing area facing the electrostatic latent image, and an elastic member for layer-regulating and thinning the developer. A positively charged one-component developer, wherein the positively charged one-component developer is composed of at least a binder resin, a colorant, a charge control agent, and a fluidizing agent, and the binder resin is at least one of the general formulas (Chemical Formula 1) and (Chemical Formula 1 2), a copolymer of (Chemical Formula 3),
And the melt viscosity at 130 ° C. is 1 × 10 ⁵ to 1 × 10 ⁷
(poise), the melt viscosity at 160 ° C. is 1 × 10 ⁴ to 1
It is a cross-linked polymer obtained by polymerizing at 10 ⁶ (poise) in the presence of a cross-linking agent, and the charge control agent is composed of at least a quaternary ammonium salt, and the quaternary ammonium salt is a positively charged one-component development. 0.05 to 5.0% by weight based on the weight of the agent, and the fluidizing agent contains 9: 1 positively charged silica and negatively charged silica.
〜5: 5 0.01 to 0.01 weight of positively charged one-component developer
3.0% by weight external addition treatment.

[0018]

[Chemical 4]

[0019]

[Chemical 5]

[0020]

[Chemical 6]

The present invention will be described in detail below. The binder resin of the one-component developer of the present invention is a vinyl polymer obtained by polymerizing or copolymerizing a vinyl monomer. Examples of the monomer styrene constituting the crosslinked polymer of the binder resin component include styrene, α-methylstyrene, styrene such as P-chlorostyrene and its substitution products, and alkyl acrylates such as acrylic acid and methyl acrylate. Ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, isobutyl acrylate, isobutyl acrylate, hexyl acrylate, phenyl acrylate, methacrylic acid alkyl esters such as methacrylic acid, methyl methacrylate, ethyl methacrylate. , Butyl methacrylate, octyl methacrylate, isobutyl methacrylate, dodecyl methacrylate, hexyl methacrylate, and the like, and monocarboxylic acids having a double bond and substituted products thereof.

The cross-linked polymer of the present invention is a polymer mainly synthesized from a vinyl-based monomer containing 0.1 to 10% by weight of a cross-linking agent monomer based on the weight of the monomer. Examples of compounds having two or more bonds include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, and diethylenic carboxylic acid esters such as ethylene glycol, tetraethylene glycol and dimethacrylate.

Further, the vinyl monomer imparting positive chargeability contains an amino group such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dibutylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dibutylaminoethyl acrylate. There are vinyl monomers.

As a method for producing these copolymers, desired known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization are adopted, and the catalyst is sufficient such as benzoyl peroxide, azobisisobutyl nitrile. A catalyst having the following catalytic ability is used. Further, for the purpose of adjusting the molecular weight, triethylamine, carbon tetrachloride, carbon tetrabromide, n-
It is also possible to use a chain transfer agent which gives the desired result, such as butyl mercaptan.

The crosslinked polymer of the present invention has a melt viscosity of 130 ° C.
Is preferably 1 × 10 ⁵ to 1 × 10 ⁷ (poise) and 160 ° C. is 1 × 10 ⁴ to 1 × 10 ⁶ (poise). Melt viscosity characteristic is 1 × 10 ⁷ (poise) at 130 ℃, 1 at 160 ℃
When it exceeds × 10 ⁶ (poise), the dispersibility of the internal additive becomes non-uniform. Further, a high fixing temperature is required at the time of fixing, and the pulverizability is deteriorated, resulting in a decrease in yield.

The melt viscosity characteristic at 130 ° C. is 1 × 10 ⁵ (pois
e) At 160 ° C., when the temperature is 1 × 10 ⁴ (poise) or less, the stress resistance decreases, and the toner particles are crushed by being stressed while being guided to the latent image, and the impact of silica impairs the fluidity. This leads to deterioration of developability.

The melt viscosity at this time was measured with a Koka type flow tester (manufactured by Shimadzu Corporation), and the measurement conditions were soybean dimension 1 × 9 mm and extrusion pressure 10 kg / cm ² .

The crosslinked polymer used in the present invention preferably contains styrene in an amount of 50 to 95% by weight as a component. When the proportion of styrene is less than 50% by weight, the toner has poor heat melting property and insufficient fixing property.

The amount of the amino group-containing monomer added is preferably 0.05 to 10% by weight based on the binder resin. If it is less than 0.05% by weight, the positive charging effect cannot be obtained. If it is 10% by weight or more, the polymerization reactivity of the resin is lowered, the production efficiency is not deteriorated, and the environmental characteristics are deteriorated.

By copolymerizing this monomer, the dispersibility of internal additives such as colorants and charge control agents can be improved. It is considered that this is because the wettability between the internal additive and the resin is improved.

The amount of the quaternary ammonium salt added is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the weight of the positively charged one-component developer. These are naturally selected depending on the developing method used. If the addition amount is small, the effect of rising the charging is not exerted, and if the addition amount is large, the dispersibility is deteriorated.

The fluidizing agent is a positively charged hydrophobic silica treated with a known coupling agent such as an amino compound, and a negatively charged hydrophobic silica treated with a known coupling agent such as hexamethylenedisilazane or dimethyldichlorosilane. The silica mixture is externally added in a proportion of 9: 1 to 5: 5 by 0.01 to 3.0% by weight based on the weight of the positively charged one-component developer. This is to secure the positive charge amount of the toner by the positively charged silica and bring out the high flow property of the negatively charged silica. When the mixing ratio of the negatively charged silica is reduced, the cohesiveness of the positively charged silica is remarkably exhibited,
Liquidity deteriorates. It is strongly seen especially under high humidity.
On the contrary, when the mixing ratio of the negatively charged silica is increased, the positive charge amount of the toner is decreased, and the transfer failure and the background fog are noticeable. A mixture of silica is 0 per weight of positively charged one-component developer.
If it is less than 01% by weight, the fluidity will decrease. If it exceeds 3.0% by weight, the amount of floating silica increases and appears as filming on the photoconductor.

As the method for producing the toner of the present invention, the copolymer and other internal additives are mixed and dispersed by heating and kneading. As the heating and kneading method at this time, a known heating and kneading machine can be used. As the heating and kneading machine, it is possible to use an apparatus for heating a kneaded material such as a three-roll type, a single-screw type, a twin-screw type, and a banbury mixer type and applying a shearing force to knead the mixture. In this experiment, a twin screw PCM30 manufactured by Ikegai Tekko KK was used. The present invention is not limited to this. The lump is roughly crushed by a cutter mill or the like, then crushed by a jet mill crusher, fine powder particles are cut by an airflow classifier, a desired particle size distribution is obtained, and an external additive such as silica is externally treated. Toner can be obtained.

The positively charged one-component developer according to the present invention has the resin as the main component as described above, but other known polymers may be mixed and used in addition to the main component as required. it can. For example, there are epoxy resin, polyester resin, polyurethane resin and the like.

If necessary, the positively charged one-component developer according to the present invention may contain an appropriate pigment or dye for the purpose of controlling coloring and charge. Such pigments or dyes include carbon black, iron black, graphite, nigrosine,
Metal complexes of azo dyes, phthalocyanine blue, cerco oil blue, DuPont oil red, aniline blue,
There are benzidine yellow, rose bengal, and mixtures thereof, and the amount of charge and the amount necessary for coloring are blended.

Further, the one-component developer according to the present invention may further contain a release agent if necessary. Further, other types of additives can be blended if necessary. Examples thereof include external additives such as titanium and alumina, fluidity imparting agents such as tin oxide and strontium titanate, and abrasives.

Further, in the positively charged one-component developer according to the present invention, a magnetic material is blended if necessary. Iron as magnetic powder
Examples include metal powders of manganese, nickel, cobalt, etc., and ferrites of iron, manganese, nickel, cobalt, zinc, etc. The average particle size of the powder is 10 μm or less, particularly preferably 7
μm or less is preferable.

[0038]

According to the present invention, by the above-mentioned constitution, by copolymerizing the positively chargeable amino group-containing monomer, the internal additive is uniformly dispersed, and the positive charge imparting ability is improved.
The charge amount distribution of is sharp. Further, the incorporation of the quaternary ammonium salt improves the rise of charging. Further, the melt viscosity at 130 ° C. is 1 × 10 ⁵ to 1 ×
10 ⁷ (poise), melt viscosity at 160 ℃ 1 × 10
High stress resistance can be secured by using a crosslinked polymer defined by ⁴ to 1 × 10 ⁶ (poise). In addition, by adding externally mixed positively charged hydrophobic silica and negatively charged hydrophobic silica to the fluidizing agent, it becomes possible to secure a positive charge amount and high fluidity, and the fluidity and the like will not deteriorate even during long-term continuous use. It is possible to provide a stable positively charged one-component developer capable of maintaining high positive chargeability, exhibiting good fixability, high image density, and free from fogging during long-term use.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to this.

FIG. 1 shows an example of a developing device in which the positively charged one-component developer of the present invention is used. The developing roller 1 is provided with a part exposed at the tip of the developing device 2, and faces the photosensitive drum with an appropriate gap. The photoconductor drum 3 is a so-called organic photoconductor in which a photoconductive layer made of an organic photoconductive material is formed on the surface of a metal base such as aluminum, and the surface of the organic photoconductor is charged as shown by an arrow E ^X. The image is exposed to the image to form an electrostatic latent image. The photosensitive drum is not limited to organic photoconductive material, and Se, Cd
An inorganic photoconductive material such as S or a-Si may be used.

The developing roller 1 is composed of an aluminum metal roller or the like whose surface is sandblasted so as to easily carry the developer, and the developer carrying roller member 4 (in the present invention, a fur brush is used) in the developing device 2 is used. The one-component developer 5 is supplied. The developing roller is not limited to aluminum, but may be a roller made of metal or the like that is surface-treated so as to easily carry and convey the developer. The developer carrying roller member is not limited to the fur brush, and may be sponge or metal. A roller-shaped member that can carry and convey the agent may be used. Behind the developer carrying roller member (fur brush) 4, there is a developer hopper 6, and the developer 5 in the developer hopper 6 is agitated by a developer supply paddle 7 while the developer carrying roller member 4 side. Sent to. The developer-carrying roller member 4 carries the sent-out developer 5 while stirring and conveys it to the developing roller 1 side, and mainly to the developing roller 1 while frictionally charging the developer 5 with the developing roller 1. Supply. The developing roller 1 carries the supplied developer 5 on its surface and conveys it to the photosensitive drum 3 side. During this conveyance, the elastic blade 8 is pressed against the surface of the developing roller 1. The elastic blade 8 is made of a rubber blade such as urethane rubber or silicon rubber, or a blade made of a suitable metal, and presses the developer 5 supplied onto the developing roller 1 to form a uniform layer having a predetermined layer thickness. A thin layer is formed so that the electrostatic latent image on the photosensitive drum 3 can be stably developed. For this development, a developing bias is applied to the developing roller 1 by a DC power supply 9, and the developing roller 1
The upper developer 5 is often attached to the electrostatic latent image on the photosensitive drum 3. Since the development in this embodiment is so-called reversal development, the developer 5 is attached to a portion of the photoconductor drum 3 where the charge is removed by image exposure to form a visible image.

Next, the material composition of the developer and the manufacturing method will be described. All parts in the examples are parts by weight. Further, all the monomer ratios in the examples are% by weight.

(Example 1) Toner used in Example 1
The material composition of a1 is shown in (Table 1).

[0044]

[Table 1]

The cross-linked polymer is styrene, butyl acrylate, dimethylaminomethyl methacrylate monomer,
It was produced by a suspension polymerization reaction in the presence of a divinylbenzene crosslinking agent. The mixture shown in (Table 1) is kneaded by heating with a twin-screw kneading extruder, finely pulverized with a jet mill, and fine powder is cut with an air stream classifier to obtain particles having an average particle size of 5 to 30 μm. It was After that, as a process of external addition, the toner base prepared as described above and the hydrophobic silica were mixed with a Henschel mixer and externally added. Finally, the agglomerates were extracted with a vibrating screen to complete toner a1. At this time, 1.5 parts by weight of the mixture of hydrophobic silica was added as an external additive.

This is a digital copying machine (Matsushita Electric) "F
A copying test was performed on 10,000 sheets by "P-C1", and the image density was measured by a reflection densitometer (Macbeth Co.) and evaluated. In the initial image, a high-concentration image with a reflection density of 1.4 was obtained, and the pigment dispersion was good and no aggregates were seen,
Also, the decrease in fluidity of the toner after 10,000 sheets is small,
A high-density copy which was comparable to the initial image was obtained. Table 2 shows the transition of the image density of each toner.

[0047]

[Table 2]

Comparative Example 1 Toner used in Comparative Example 1
The material composition of a2 is shown in (Table 3).

[0049]

[Table 3]

The amino group-containing monomer was not copolymerized, only the cross-linked polymer of styrene-butyl acrylate monomer was used as the binder resin, and the mixture shown in (Table 3) was heated and kneaded by a twin-screw kneading extruder. Then, fine pulverization was performed with a jet mill, and fine powder was cut with an air stream classifier to obtain particles having an average particle size of 5 to 30 μm. After that, as a process of external addition, the toner base prepared as described above and the hydrophobic silica were mixed with a Henschel mixer and externally added. Finally, the agglomerates were extracted with a vibrating screen to complete toner a2. At this time, 1.5 parts by weight of negatively charged hydrophobic silica is externally added as an external additive.

This is a digital copier (Matsushita Electric) "F
A copying test was performed on 10,000 sheets by "P-C1", and the image density was measured by a reflection densitometer (Macbeth Co.) and evaluated. Since the positive charge amount of the toner was low, the image density was low from the beginning, and the toner was scattered in the machine, so that a practical image could not be obtained. In addition, the dispersion of the internal additive was poor, and many aggregates of carbon black were observed.

Comparative Example 2 Toner used in Comparative Example 2
The material composition of a3 is shown in (Table 4).

[0053]

[Table 4]

In order to increase the charge amount of the toner a2 of the comparative example to that of the toner a1 of the example 1, the amount of the charge control agent added in the comparative example 1 was increased to 6% by weight. The mixture shown in (Table 4) is kneaded by heating with a twin-screw kneading extruder, finely pulverized with a jet mill, and fine powder is cut with an air stream classifier to obtain particles having an average particle size of 5 to 30 μm. It was After that, as a process of external addition, the toner base prepared as described above and the hydrophobic silica were mixed with a Henschel mixer and externally added. Finally, the agglomerates were extracted with a vibrating screen to complete toner a3. At this time, 1.5 parts by weight of positively charged hydrophobic silica was added as an external additive.

This is a digital copying machine (Matsushita Electric) "F
A copying test was performed on 10,000 sheets by "P-C1", and the image density was measured by a reflection densitometer (Macbeth Co.) and evaluated. Although the charge amount of the toner was high, the image density was low from the initial stage, and the image density was lowered during the copying test, and a practical image was not obtained. At this time, the dispersion of the internal additive, especially the pigment, in the toner was remarkably observed. In addition, the charge amount distribution is broad, the particle size distribution of the toner remaining in the developing device after the copy test is large, and the small particle size component is apparently large, so selective development has occurred, so image density Seems to have decreased.

[0056]

As described above, in the present invention, a positively chargeable amino group-containing monomer is copolymerized with a crosslinked binder resin,
By using a mixture of quaternary ammonium salt as the charge control agent and positively and negatively charged hydrophobic silica as the fluidizing agent,
Even when a high-viscosity crosslinked polymer is used, the non-uniformity of the dispersion of the internal additive is improved and the dispersibility is improved. In addition to improving the positive charging property, the distribution of the amount of charge is sharpened, the rising of charging is improved, high fluidity can be maintained even under high humidity, excellent stress resistance, stable fixing property, It is possible to obtain a stable, positively charged one-component developer with high image density, high image density, and low deterioration in fluidity even after long-term continuous use.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a developing mechanism in which a developer according to an embodiment of the present invention is used.

[Explanation of symbols]

 1 Developing Roller 2 Developing Device Main Body 3 Photosensitive Drum 4 Developer Holding Roller Member 5 Developer 6 Developer Holding Chamber 7 Developer Supply Paddle 8 Elastic Blade 9 DC Power Supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G03G 9/08 375

Claims (1)

[Claims] 1. An electrostatic latent image carrier for carrying an electrostatic latent image, a developer hopper for containing a developer, and a developer carrying roller member for carrying and carrying the developer while frictionally charging the developer. A positively charged one-component developer used in a developing device, which comprises: a developing roller that conveys the developer to a developing area facing the electrostatic latent image; and an elastic member that regulates the layer of the developer and thins the layer. Wherein the positively charged one-component developer is composed of at least a binder resin, a colorant, a charge control agent and a fluidizing agent, and the binder resin is at least one of the general formulas (Chemical formula 1), (Chemical formula 2), (Chemical formula 2), A copolymer of the chemical formula 3), and
Melt viscosity at 30 ° C. is 1 × 10 ⁵ to 1 × 10 ⁷ (pois
e), the melt viscosity at 160 ° C. is 1 × 10 ⁴ to 1 × 1.
It is a cross-linked polymer obtained by polymerizing at 0 ⁶ (poise) in the presence of a cross-linking agent, and the charge control agent is composed of at least a quaternary ammonium salt, and the quaternary ammonium salt is the positively-charged one. 0.05 to 5.0% by weight based on the weight of the component developer, and the fluidizing agent contains positively charged silica and negatively charged silica at a ratio of 9: 1 to 5: 5 with respect to the weight of the positively charged one-component developer. A positively charged one-component developer characterized by being externally added at 0.01 to 3.0% by weight. [Chemical 1] [Chemical 2] [Chemical 3]