KR100503362B1 - Magnetic toner composition having superior electrification homogeneity - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner composition having excellent charge uniformity, in particular, a magnetic toner base particle comprising a binder resin and a magnetic body, a conductive fine powder having a specific surface area of 30 to 300 m 2 / g, and a specific surface area of 100 to 240 m 2 / g. It is possible to improve charging characteristics, including hydrophobic silica and inorganic fine powder with an average particle diameter of 0.1 to 4.0 μm, and to maintain uniform charging characteristics, thereby reducing the electrostatic charge gap between residual toner and replenished toner in a cartridge or developing device. A magnetic toner composition having excellent charge uniformity.

Description

Magnetic toner composition excellent in charge uniformity {MAGNETIC TONER COMPOSITION HAVING SUPERIOR ELECTRIFICATION HOMOGENEITY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner composition, and more particularly, to improve charging characteristics, and to maintain a uniform charging characteristic so as to reduce the electrostatic charge gap between residual toner and replenished toner in a cartridge or a developing apparatus. A magnetic toner composition having excellent uniformity.

Magnetic toner is used to develop an electrostatic charge image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

In recent years, with the development of computers, OA devices and the like, various printers and copiers are commercially available as various information output devices. As an image forming method of these various printers or copiers, a method using an electrostatic charge image is widely used.

In general, image formation is performed in the following process.

1. The process includes a charging step of imparting a constant electrostatic charge to a latent image bearing member having a photosensitive layer made of a photoconductive material;

2. an exposure step of forming an electrostatic image corresponding to the original on the surface of the latent image bearing member by exposure of the original or a laser;

3. a developing step of developing the electrostatic image with a developer to form a toner image;

4. A transfer step of transferring the toner image onto a transfer material such as paper;

5. A fixing step of fixing the toner transferred to a transfer material such as paper by heating or pressing; And

6. A cleaning process for cleaning the toner and deposits remaining on the latent image carrier without being transferred.

By repeating each of the above steps, desired copies or printer outputs can be obtained.

In the developing step, a step of applying a static charge to the toner is performed. The process of imparting the electrostatic charge to the toner is carried out through the two-component toner which mixes the toner with the carrier made of ferrite and imparts the electrostatic charge to the toner, and is transferred through the narrow gap between the sleeve and the doctor blade. It is divided into one-component toner which gives a lower value.

The toner to be given the electrostatic charge is present in a toner cartridge or a developing apparatus. The toner in the cartridge or the developing device is mixed by the stirring bar or the stirring roller, and is subjected to the electrostatic charge by the mixing. The toner to which the electrostatic charge is applied is consumed and the toner sensor in the cartridge or the developing device detects whether the toner remains. When the remaining amount of toner decreases below a certain amount, the toner sensor detects this and requests replenishment of new toner. When replenishment of new toner is made, a mixture of residual toner and fresh toner is made in the cartridge or the developing apparatus. At this time, the remaining toner is a state in which the static charge is already given by the stirring bar or the stirring roller, and the newly loaded toner is in the state where the static charge is not applied, and a static charge gap is generated between the remaining toner and the loaded toner. Due to the electrostatic charge gap, an image of a copy or a printer output is blurred or an uneven image is obtained.

Therefore, there is a need for a study of a magnetic toner composition having excellent charge uniformity as well as a reduction in the electrostatic charge gap between residual toner and replenished toner in a cartridge or a developing apparatus by maintaining uniform charging characteristics.

In order to solve the above problems, the present invention has a uniform charging characteristic to not only reduce the electrostatic charge gap between the remaining toner in the cartridge or the developing apparatus and the toner replenished, but also to improve the charging characteristic. It is an object to provide a composition.

In order to achieve the above object, the present invention provides a magnetic toner composition,

a) magnetic toner base particles comprising a binder resin and a magnetic body;

b) conductive fine powder with a specific surface area of 30 to 300 m 2 / g;

c) hydrophobic silica with a specific surface area of 100 to 240 m 2 / g; And

d) inorganic fine powder with an average particle diameter of 0.1 to 4.0 탆

It provides a magnetic toner composition comprising a.

Hereinafter, the present invention will be described in detail.

The inventors of the present invention have studied a method for reducing the electrostatic charge gap between residual toner and replenished toner in a cartridge or developing device in a magnetic toner composition, and the conductive toner particles, hydrophobic silica, and inorganic fine powder are applied to the magnetic toner base particles. As a result of the preparation of the magnetic toner, it was confirmed that not only the charging characteristics of the toner composition were improved, but also the uniform charging characteristics were retained to reduce the electric charge between the toner compositions, and thus the present invention was completed.

In the magnetic toner composition, the magnetic toner base particles comprising a binder resin and a magnetic body, a conductive fine powder having a specific surface area of 30 to 300 m 2 / g, a hydrophobic silica having a specific surface area of 100 to 240 m 2 / g, and an average particle diameter of 0.1 A magnetic toner composition comprising an inorganic fine powder having a thickness of 4.0 μm to 4.0 μm.

As the conductive fine powder having a specific surface area of 30 to 300 m 2 / g of b) used in the present invention, a fine metal oxide powder or conductive carbon black may be used. Examples of the metal oxide include magnetite, aluminum oxide, titanium oxide, and tin oxide. , Zinc oxide, indium oxide, or a compound thereof can be used.

The specific surface area of the conductive fine powder is preferably 30 to 300 m ² / g, more preferably 100 to 250 m ² / g. When the specific surface area is less than 30 m ² / g, the conductive fine powder is insufficiently present on the surface of the toner base particles, and charging uniformity is reduced. When the specific surface area exceeds 300 m ² / g, the adhesion force between the conductive fine powders is increased and the toner base is increased. There is a problem that separation occurs on the surface of the particles, resulting in degradation of image contamination and uniformity of charge. In addition, the electrical resistance of the conductive fine powder is preferably 10 ^-2 to 10 Ω · cm. If the electrical resistance is less than 10 ^-2 Ω · cm, the conductive fine powder interferes with the charging of the toner base particles to obtain a print image with a low image density. If the electrical resistance is more than 10 Ω · ㎝, the electrical conductivity of the conductive fine powder is weak. Since it is difficult to impart the charge uniformity between the toner base particles, there is a problem that an image unevenness occurs due to a gap between the static charge of the remaining toner and the static charge of the replenished toner.

The conductive fine powder is preferably included in an amount of 0.1 to 0.5 parts by weight, more preferably 0.15 to 0.35 parts by weight, based on 100 parts by weight of the toner base particles. If the content is less than 0.1 part by weight, the formation of the conductive fine powder layer on the surface of the toner base particles is insufficient, and the charge uniformity effect is lowered. If the content is more than 0.5 part by weight, frictional charging between the magnetic toner and the developing sleeve is difficult to occur. There is a problem in that the density is low, so that a poor image is obtained and the charging uniformity of the toner particles is lowered.

The charge uniformity of the magnetic toner is secured by using a one-component developer in which a conductive fine powder having a specific surface area of 30 to 300 m ² / g is added to the surface of the magnetic toner base particles. The magnetic toner is subjected to an electrostatic charge by a stirring bar or a stirring roller in the cartridge or the developing apparatus. In this case, the magnitude of the static charge applied to the magnetic toner varies depending on the binder resin, the magnetic material, or the charge control agent in the toner base particles, and the magnitude of the static charge varies depending on the size of the toner base particles. Since the toner base particles have a distribution of sizes, the electrostatic charges imparted to the respective toner base particles also have distributions, thereby causing a static charge gap between the toner base particles. The magnetic toner composition of the present invention has the effect of preventing blurring or non-uniform output of an image of a copy or a printer output by eliminating the electrostatic charge gap between the toner base particles by the conductive fine powder present on the surface of the toner base particles. There is. In addition, when the new toner is loaded into the residual toner in the cartridge or the developing apparatus, the gap between the static charge of the residual toner and the static charge of the supplied toner is eliminated to increase the compatibility between the residual toner and the loaded toner, thereby preventing image irregularities. There is.

The hydrophobic silica having a specific surface area of 100 to 240 m ² / g of c) used in the present invention solves the problem of deterioration in fluidity and chargeability of the toner particles when only the conductive fine powder and the inorganic fine powder are added to the magnetic toner base particles. It plays a role.

The specific surface area of the hydrophobic silica is preferably 100 to 240 m ² / g, more preferably 130 to 200 m ² / g. If the specific surface area is less than 100 m ² / g, the effect of imparting fluidity improvement to the toner is insufficient, and if a large number of solid images are output, image staining may occur on the solid image, and 240 m ² / g When exceeding this, silica is buried on the surface of the toner base particles, thereby reducing the effect of imparting fluidity to the toner, thereby lowering the effects of the conductive fine powder and the inorganic fine powder.

The hydrophobic silica is preferably included in 0.1 to 0.5 parts by weight based on 100 parts by weight of the total toner base particles. If the content is less than 0.1 parts by weight, there is a problem that the fluidity imparting effect is insufficient in the toner, and if it exceeds 0.5 parts by weight, the charge uniformity of the toner base particles is deteriorated.

As the inorganic fine powder having an average particle diameter of 0.1 to 4.0 μm of d) used in the present invention, a fine powder of an inorganic oxide or a fine powder of a carbonate compound may be used. Examples of the inorganic oxides include oxides such as zinc oxide or tin oxide; Double oxides such as strontium titanate, barium titanate, calcium titanate, strontium zirconate, or calcium zirconate; Or carbonate compounds such as calcium carbonate or magnesium carbonate.

It is preferable that the average particle diameter of the said inorganic fine powder is 0.1-4.0 micrometers, More preferably, it is 0.2-3.0 micrometers. If the average particle diameter is less than 0.1 µm, the diameter of the inorganic fine powder becomes too small to increase the adhesion to the magnetic toner surface, so that the separation on the magnetic toner surface is difficult to be performed, and the polishing effect is reduced, and the toner on the latent image carrier There is a problem in that an effect of preventing filming cannot be obtained. In addition, when the average particle diameter exceeds 4.0 mu m, there is a problem in that the mixing with the magnetic toner becomes insufficient, it is easy to scatter on the sleeve surface, and contaminates the charging roller of the charging device, thereby lowering the image density. In addition, although the anti-pilling effect of the toner on the latent image bearing member can be obtained, the inorganic fine powder having a higher hardness and larger diameter tends to damage the surface of the photosensitive member which is the latent image bearing member.

The inorganic fine powder is preferably included in an amount of 0.5 to 1.5 parts by weight, and more preferably 0.7 to 1.2 parts by weight, based on 100 parts by weight of the total magnetic toner base particles. If the content is less than 0.5 parts by weight, the formation of the inorganic fine powder layer on the developing sleeve is insufficient, so that it is difficult to expect the anti-pilling effect of the toner on the latent image carrier, and when it exceeds 1.5 parts by weight, the toner on the latent image carrier Although the anti-pilling effect is excellent, there is a problem in that frictional charging between the magnetic toner and the developing sleeve is less likely to occur, resulting in a poor image having a low image density.

The magnetic toner base particles may include a binder resin and a magnetic body, and may further include a colorant or an additive.

As the binder resin, conventionally known ones can be used. As a specific example, a polyester resin, a styrene resin, an acrylic resin, a styrene acrylic resin, an epoxy resin, a polyamide resin, a polyethylene resin, a styrene vinyl acetate resin, or a mixture thereof can be used. The binder resin is preferably contained in 25 to 75% by weight in the magnetic toner base particles for the electrostatic charge image development.

As the magnetic body, ferromagnetic elements, alloys or compounds thereof, granular magnetic components, or acicular magnetic components can be used. As specific examples, alloys and compounds such as magnetite, fematite, ferrite, iron, cobalt, nickel, or manganese, other ferromagnetic alloys, magnetic oxides, and the like can be used. The magnetic body is preferably a fine powder having an average diameter of 1 μm or less, and preferably contained in an amount of 20 to 70 wt% in the magnetic toner base particles for electrostatic image development.

As the colorant, split black, nigurosine dye, aniline blue, chrome yellow, phthalocyanine blue, lamp black, rose bengal, ultramarine blue, methylene blue chloride, or the like can be used. Preferably, the colorant is included in an amount of 10 wt% or less in the magnetic toner base particles for electrostatic image development.

As said additive, the charge regulator used conventionally; Fixative aids; Lubricants such as polytetrafluoroethylene (teflon), polyvinylidene fluoride, or fatty acid metal salts; Fluidity imparting agents such as titanium dioxide or aluminum oxide surface-treated with an abrasive such as cerium oxide or silicon carbide, a surface treatment agent such as silicone oil, various modified silicone oils, or a silane coupling agent; Anti-caking agents; Alternatively, fixing aids such as carbon black or low molecular weight polyethylene may be used. In addition, release agents such as low molecular weight polyethylene, low molecular weight polypropylene, or carnauba wax may be used for the purpose of improving releasability during heat roller fixing. .

It is preferable that the average particle diameter of the above magnetic toner base particles is 5 to 12 mu m.

The magnetic toner composition according to the present invention is preferably used for electrostatic image development.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Example 1

(Production of Magnetic Toner Base Particles)

54 parts by weight of styrene acrylic resin powder, 5 parts by weight of polypropylene resin powder, 1 part by weight of metal complex dye dye powder as a charge control agent, and 40 parts by weight of magnetite as a magnetic substance were uniformly mixed using a Henschel mixer. It melt-kneaded using the extruder. The sheet was stretched into a sheet, cooled, and coarsely ground to a size of several millimeters by a hammer mixer, finely ground by a jet mill, and classified by a classifier to prepare magnetic toner base particles having an average particle diameter of 7.5 mu m.

(Magnetic Toner Manufacturer)

0.2 parts by weight of a conductive fine powder having a specific surface area of 30 m 2 / g and an electrical resistance of 10-1 to 10 ^-2 Ω · cm, 0.5 parts by weight of P25 (Degussa, Germany) as an inorganic fine powder, 0.5 parts by weight of RA200HS was added to the hydrophobic silica, followed by stirring and mixing for 5 minutes with a Henschel mixer to prepare a magnetic toner for developing an electrostatic image.

Examples 2-12, and Comparative Examples 1-14

Except for using the composition ratio of Table 1 in Example 1 was carried out in the same manner as in Example 1.

division Conductive Fine Powder Mineral fine powder Silica Specific surface area (㎡ / g) Electric resistance (Ωcm) Parts by weight Average particle size (㎛) Parts by weight Specific surface area (㎡ / g) Parts by weight Example 1 30 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 0.5 Example 2 100 1 to 5 0.2 0.5 0.5 130 0.5 Example 3 250 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 0.5 Example 4 250 10 ^-1 to 10 ^-2 0.1 0.5 0.5 130 0.5 Example 5 30 10 ^-1 to 10 ^-2 0.1 0.5 0.5 130 0.5 Example 6 250 10 ^-1 to 10 ^-2 0.5 0.5 0.5 130 0.5 Example 7 30 10 ^-1 to 10 ^-2 0.5 0.5 0.5 130 0.5 Example 8 250 10 ^-1 to 10 ^-2 0.2 0.5 1.5 130 0.5 Example 9 250 10 ^-1 to 10 ^-2 0.2 0.5 1.0 130 0.1 Example 10 250 10 ^-1 to 10 ^-2 0.1 0.5 0.5 130 0.1 Example 11 60 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 0.5 Example 12 60 10 ^-1 to 10 ^-2 0.5 0.5 0.5 130 0.5 Comparative Example 1 - - - 0.5 0.2 130 0.5 Comparative Example 2 400 10 ^{-1 to} 1 0.2 0.5 0.5 130 0.5 Comparative Example 3 550 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 0.5 Comparative Example 4 15 10 ^{-1 to} 1 0.2 0.5 0.5 130 0.5 Comparative Example 5 250 10 ^-1 to 10 ^-2 1.0 0.5 1.0 130 0.5 Comparative Example 6 250 10 ^-1 to 10 ^-2 0.2 0.5 - 130 0.5 Comparative Example 7 250 10 ^-1 to 10 ^-2 0.2 0.5 0.2 130 - Comparative Example 8 250 10 ^-1 to 10 ^-2 0.2 0.5 2.0 130 0.5 Comparative Example 9 250 10 ^-1 to 10 ^-2 0.2 0.05 0.5 130 0.5 Comparative Example 10 250 10 ^-1 to 10 ^-2 0.2 5.0 0.5 130 0.5 Comparative Example 11 250 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 0.05 Comparative Example 12 250 10 ^-1 to 10 ^-2 0.2 0.5 0.5 130 1.0 Comparative Example 13 250 10 ^-1 to 10 ^-2 0.2 0.5 0.5 50 0.5 Comparative Example 14 250 10 ^-1 to 10 ^-2 0.2 0.5 0.5 300 0.5

Experimental Example

The magnetic toners prepared in Examples 1 to 12 and Comparative Examples 1 to 14 were used in a developing apparatus using a commercially available magnetic one-component developing system (Canon Corporation, GP-605), which is composed of a jumping-type developing mechanism. A new toner is added in the presence of residual toner and outputs up to 20,000 sheets at room temperature and humidity (20 ° C, 55% RH) to measure latent image carrier peeling, latent image carrier damage, image density, and scattering. It was. The evaluation was carried out according to the following evaluation criteria, and the results are shown in Table 2 below.

Evaluation standard Latent Image Support Film Latent Carrier Damage Burn density arsenic acid A No occurrence No damage Keep image density No scattering B 5,000 pieces Slightly damaged Lowered after 5,000 sheets 10,000 sheets scattered C 10,000 pieces generated Damage occurs Lowered after 2,000 sheets 5,000 sheets scattered

division Latent image carrier filming Latent Carrier Damage Burn density arsenic acid Example 1 A A A A Example 2 A A A A Example 3 A A A A Example 4 A A A A Example 5 A A A A Example 6 A A A A Example 7 A A A A Example 8 A A A A Example 9 A A A A Example 10 A A A A Example 11 A A A A Example 12 A A A A Comparative Example 1 A A C A Comparative Example 2 A A A A Comparative Example 3 C A C A Comparative Example 4 A B C B Comparative Example 5 A B A A Comparative Example 6 B B A C Comparative Example 7 A A B A Comparative Example 8 A A B C Comparative Example 9 B C C A Comparative Example 10 B A C C Comparative Example 11 C A B A Comparative Example 12 A A B A Comparative Example 13 A B B A Comparative Example 14 C C B A

Through the above Table 1, magnetic toner base particles, conductive fine powder having a specific surface area of 30 to 300 m 2 / g, hydrophobic silica having a specific surface area of 100 to 240 m 2 / g, and inorganic fine powder having an average particle diameter of 0.1 to 4.0 μm It was confirmed that the magnetic toner compositions for electrostatic image development of Examples 1 to 12 included were superior to latent image carrier peeling, latent image carrier damage, image concentration, and scattering as compared with the magnetic toner compositions of Comparative Examples 1 to 14.

As described above, the magnetic toner composition of the present invention has a uniform charging characteristic, which can not only reduce the electrostatic charge gap between the remaining toner in the cartridge or the developing apparatus and the toner replenished, but also improve the charging characteristic. It works.

Claims (10)

In the magnetic toner composition, a) magnetic toner base particles comprising a binder resin and a magnetic body; b) conductive fine powder with a specific surface area of 30 to 300 m 2 / g; c) hydrophobic silica with a specific surface area of 100 to 240 m 2 / g; And d) inorganic fine powder with an average particle diameter of 0.1 to 4.0 탆 Magnetic toner composition comprising a. The method of claim 1, a) 100 parts by weight of magnetic toner base particles comprising a binder resin and a magnetic body; b) 0.1 to 0.5 parts by weight of conductive fine powder having a specific surface area of 30 to 300 m 2 / g; c) 0.1 to 0.5 parts by weight of hydrophobic silica having a specific surface area of 100 to 240 m 2 / g; And d) 0.5 to 1.5 parts by weight of inorganic fine powder having an average particle diameter of 0.1 to 4.0 μm Magnetic toner composition comprising a. The method of claim 1, The magnetic toner composition according to claim b, wherein the conductive fine powder having a specific surface area of 30 to 300 m 2 / g is a metal oxide fine powder or conductive carbon black. The method of claim 3, The magnetic toner composition, wherein the metal oxide is selected from the group consisting of magnetite, aluminum oxide, titanium oxide, tin oxide, zinc oxide, indium oxide, and compounds thereof. The method of claim 1, The inorganic fine powder having an average particle diameter of 0.1 to 4.0 µm in d) is selected from the group consisting of zinc oxide, tin oxide, strontium titanate, barium titanate, calcium titanate, strontium zirconate, calcium zirconate, calcium carbonate, and magnesium carbonate. Magnetic toner composition that is a fine powder. The method of claim 1, The binder resin of a) is contained in 25 to 75 parts by weight of the binder resin with respect to 100 parts by weight of the magnetic toner base particles, the magnetic body is contained in 20 to 70 parts by weight based on 100 parts by weight of the magnetic toner base particles . The method of claim 6, The magnetic toner composition further comprises a charge adjuster, a fixing aid, a lubricant, an abrasive, a fluidity imparting agent, an anti-caking agent, a fixing aid, or a release agent. The method of claim 1, A magnetic toner composition having an average particle diameter of the magnetic toner base particles of a) of 5 to 12 µm. The method of claim 1, A magnetic toner composition, wherein the magnetic toner composition is for electrostatic image development. 10. The magnetic toner composition according to any one of claims 1 to 9, wherein the conductive fine powder has an electrical resistance value of 10 ^-2 to 10 Ω · cm.