JP2001249488A - Magnetic single-component toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic single-component toner having good fluidity which can suppress the consumption of toner and with which an image having enough image density and reproducing sharp fine lines such as characters can be obtained. SOLUTION: The magnetic single-component toner contains (A) fine particle magnetic toner having 4 to 10 μm volume average particle size and (B) coarse magnetic toner having 14 to 25 μm volume average particle size by 1.0 to 7.0 pts.wt. to 100 pts.wt. of the toner (A). The toner shows two peaks in the grain size distribution and has 5 to 11 μm volume average particle diameter, <=<30% in number of particles having <=5 μm particle diameter and 2.1 to 4.0 volume % of particles having >=16 μm particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic one-component toner,
More specifically, an image having a sufficient image density and capable of sharply reproducing fine lines such as characters can be obtained, the toner consumption can be suppressed to a low level, and the fluidity of the toner is good. And a magnetic one-component toner in which aggregation and bridge formation of the toner hardly occur.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic system, an optical image is converted on a photoreceptor into an electronic latent image such as an electrostatic image, and then colored toner particles are colored on the electrostatic latent image. A visible image is formed by applying the toner (development), and the toner image is transferred to a recording medium such as paper, and then fixed by heating, pressing, or the like to obtain a copy. Such an electrophotographic system is widely applied to a laser printer, a facsimile, etc. in addition to a copying machine because of its excellent operability, quickness, stability of a final image, and the like. The design concept of the toner particles varies depending on the development method of electrophotography. A well-known electrophotographic developing method is a two-component developing method using a toner and a carrier such as ferrite and iron powder as a developer,
There is a magnetic one-component developing method using only magnetic toner and a non-magnetic one-component developing method using only non-magnetic toner. Among them, the magnetic one-component developing system is characterized in that the developing device is compact and the printing durability is excellent. In the magnetic one-component developing method, a toner carrier such as a cylindrical sleeve having a magnet roller mounted at the center is disposed with a certain gap from the photoconductor, and a thin layer of insulating magnetic toner is formed on the sleeve. Transported to An alternating electric field is applied between the photosensitive member and the sleeve, and the charged magnetic toner particles are developed into an electrostatic latent image while flying. The application of the triboelectric charge of the magnetic toner is mainly performed by contact abrasion with the sleeve surface and abrasion between the toners. The thickness of the toner layer on the sleeve is formed smaller than the gap between the photosensitive member and the sleeve in the development area. As the toner, a magnetic one-component toner obtained by dispersing magnetic powder in a thermoplastic resin as a toner binder and further blending various additives is widely used. The magnetic one-component toner is obtained by blending, for example, a magnetic powder, a wax, a charge control agent, and the like with a thermoplastic resin, melt-kneading the mixture using a heating kneader, and uniformly dispersing the magnetic powder.
It is manufactured by pulverizing a material cooled to room temperature with a pulverizer, further removing coarse powder and fine powder by classification, and adjusting to a desired particle size. At this time, an inorganic fine powder such as silica is often added for the purpose of improving the fluidity and durability of the toner. To get a good image,
It is thought that it is important to sharpen the charge distribution of the toner.
Generally, an electrostatic latent image on a photoreceptor cannot be faithfully reproduced, resulting in problems such as insufficient image density, crushed fine lines, and bleeding. To sharpen the toner charge distribution,
A method of sharpening the particle size distribution of the toner, a method of improving the dispersibility of additives such as magnetic powder, and the like can be considered. In recent years, the demand for higher resolution of image quality has increased, and fine toners having an average particle size of 10 μm or less have been favored. Regarding uniform dispersion technology of raw materials and classification technology of pulverized toner,
Further innovation is desired. As a toner having an average particle diameter of 10 μm or less, for example, a non-magnetic toner having a weight average particle diameter of 6 to 10 μm, a particle diameter of most particles of 5 to 8 μm, and an extremely sharp particle size distribution is proposed. (Japanese Patent Application Laid-Open No. 58-129439). However, in this non-magnetic toner, the formed image tends to lack sharpness. This tendency is particularly pronounced when the cartridge is used for a reused cartridge. Further, by using magnetic powder having an average particle diameter of 4 to 10 μm and excellent dispersibility, fine particles having a particle diameter of 5 μm or less
個数 60 number% is set as large as possible.
A magnetic toner in which particles having a size of 6.0 μm or more are defined to be 2.0% by volume or less has been proposed (Japanese Patent No. 2603287).
In the present invention, it is described that the fine particle toner having a particle diameter of 5 μm or less faithfully reproduces the edge portion of the electrostatic latent image and dramatically improves the sharpness of the image quality. In addition, there is a problem that the toner consumption increases.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides an image having a sufficient image density and capable of sharply reproducing fine lines such as characters, and reducing toner consumption. In addition to being able to suppress, the fluidity of the toner is good,
It is an object of the present invention to provide a magnetic one-component toner in which aggregation of toner and formation of a bridge in a developing device are unlikely to occur, particularly, a toner suitable for filling a cartridge to be reused.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a magnetic one-component toner having excellent functions as described above. A magnetic one-component toner having a particle size distribution of a two-peak structure in which a coarse particle magnetic toner having a specific average particle size is blended in a small ratio, and having a specific particle size property,
It has been surprisingly found that the object can be met, and the present invention has been completed based on this finding. That is, the present invention provides (1) (A) a fine particle magnetic toner having a volume average particle diameter of 4 to 10 μm, and (B) a coarse particle magnetic toner having a volume average particle diameter of 14 to 25 μm per 100 parts by weight. 7.0
What is claimed is: 1. A magnetic one-component toner having a particle size distribution of a two-ridge structure including parts by weight, having a volume average particle size of 5 to 11 μm and a particle size of 5 μm.
m is 30% by number or less and the particle size is 16μ.
m, wherein the content of particles having a particle size of m or more is 2.1 to 4.0% by volume, the composition of the magnetic one-component toner (2), the fine particle magnetic toner of the component (A), and the coarseness of the component (B). 2. The magnetic one-component toner according to item 1, wherein the composition of the particle magnetic toner is substantially the same, and (3) the magnetic one-component toner according to item 1, used as a toner for filling a reuse cartridge. is there.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic one-component toner of the present invention comprises:
Component (A) is a fine particle magnetic toner having a volume average particle diameter of 4 to 10 μm, and 100 parts by weight of component (B) is a coarse particle magnetic toner having a volume average particle diameter of 14 to 25 μm. It has a particle size distribution of a double peak structure containing 0 parts by weight. In the developing method using the magnetic one-component toner, the toner on the developing sleeve is considered to exhibit a triboelectric charging function only by the friction between the toners and the friction between the toner and the surface of the sleeve.
Compared to a developing method using a two-component toner using a carrier and a non-magnetic toner as a developer, the frequency of contact friction of the toner is extremely low, which is considered to be disadvantageous in terms of charging characteristics. But,
As in the present invention, by adding a small amount of the coarse particle magnetic toner having the large particle diameter of the component (B) to the fine particle toner of the component (A), the coarse particle magnetic toner hardly transfers to the photoreceptor in the developing process. Tends to be held on the sleeve,
It is considered to play a counterpart in triboelectric charging with other toner particles. Therefore, the triboelectric charging area is increased by adding the coarse magnetic toner of the component (B) in an amount of 1.0 to 7.0 parts by weight based on 100 parts by weight of the fine magnetic toner of the component (A). Therefore, it is considered that the charging characteristics of the toner contributing to the development on the developing sleeve are improved, and as a result, a sufficient image density can be obtained and fine lines such as characters can be sharply reproduced. When the volume average particle diameter of the coarse magnetic toner of the component (B) exceeds 25 μm or the added amount exceeds 7.0 parts by weight, the proportion of coarse particles in the particle size distribution of the obtained magnetic one-component toner increases. Too much, the distribution of the charge amount becomes broad, and the image quality is deteriorated such as a decrease in image density. The coarse magnetic toner of the component (B) has a volume average particle diameter of 14 μm.
If the amount is less than 1.0 or less than 1.0 part by weight, the effect of adding the coarse magnetic toner of the component (B) is not sufficiently exhibited, and the object of the present invention cannot be achieved. Further, the volume average particle diameter of the fine particle magnetic toner of the component (A) is 4%.
When the average particle diameter is out of the range of 10 to 10 μm, it is difficult to obtain a toner having the following particle size properties (particle size distribution), and the object of the present invention cannot be sufficiently achieved. In the magnetic one-component toner of the present invention, the volume average particle diameter is 5 to 11 μm, the content of particles having a particle diameter of 5 μm or less is 30% by number or less, and the content of particles having a particle diameter of 16 μm or more is 2.1 to 4.1%. 0% by volume, preferably 2.
It needs to be 2 to 3.0% by volume. If any of these properties deviates from the above range, the image density is not sufficient, an image capable of sharply reproducing fine lines cannot be obtained, and therefore, the amount of consumed toner cannot be suppressed low, or The object of the present invention cannot be sufficiently achieved, such as poor fluidity. In the magnetic one-component toner of the present invention, it is preferable that the composition of the fine particle magnetic toner of the component (A) and the composition of the coarse particle magnetic toner of the component (B) are substantially the same. The composition of the magnetic one-component toner of the present invention is not particularly limited, and the composition of a normal magnetic one-component toner, for example, contains a toner binder and a magnetic powder as essential components, and optionally includes a colorant, a charge control agent, and a release agent. And a composition containing a fluidizing agent and the like.

Here, as the toner binder, for example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene and its substituted products; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene Copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene -Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer and the like Styrene-based Coalescence: polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin , Polyvinyl butyral, terpene resin, cumarone indene resin, petroleum resin and the like. Examples of the magnetic powder include conventionally known magnetic powders such as iron, cobalt, nickel, magnetite, hematite, and ferrite. The particle size of the magnetic powder is usually 0.1 to 2.0 μm.
m, preferably in the range of 0.1 to 0.6 μm. The magnetic powder is used in an amount of usually 50 to 110 parts by weight, preferably 60 to 100 parts by weight, based on 100 parts by weight of the toner binder. As the colorant, conventionally known organic or inorganic colorants, for example, carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetite, iron black, benzidine yellow, disazo yellow, quinacdrine, naphthol type Examples include azo pigments, quinacridone, rhodamine B, phthalocyanine, titanium white, zinc white, and the like. In addition, magnetic 1
In the component toner, when the magnetic powder itself is colored (black), the use of the colorant is not essential. The charge control agent is a substance capable of giving a positive or negative charge by triboelectric charging. Examples of such a substance include nigrosine base EX (manufactured by Orient Chemical Industries), P-51 (manufactured by Orient Chemical Industries), Copy Charge PXVP435 [manufactured by Hoechst Co., Ltd.], alkoxylated amine, alkylamide, molybdate chelate pigment, PLZ1001 [manufactured by Shikoku Kasei Kogyo], Bontron S-22 [manufactured by Orient Chemical Industries], Bontron S-84 [orient Chemical Co., Ltd.], Bontron E-81 [Orient Chemical Co., Ltd.], Bontron E-84 [Orient Chemical Co., Ltd.], Spiron Black TRH [Hodogaya Chemical Co., Ltd.], thioindigo pigment, Copy Charge NXVP4
34, Bontron E-89 [manufactured by Orient Chemical Industry Co., Ltd.], magnesium fluoride, carbon fluoride, oxycarboxylic acid metal complex, dicarboxylic acid metal complex, amino acid metal complex, diketone metal complex, diamine metal complex, azo group-containing benzene- Benzene derivative skeleton metal complex, azo group-containing benzene-naphthalene derivative skeleton metal complex, benzyldimethyl-hexadecylammonium chloride, decyl-trimethylammonium chloride, metal complex, nigrosine base, nigrosine hydrochloride, safranin, crystal violet, quaternary ammonium salt , Alkylsalicylate metal complexes, calixarene compounds, boron compounds, fluorinated quaternary ammonium salts, azo metal complexes, triphenylmethane dyes, dibutyltin oxide, etc. Various things can be applied. The charge control agent is used in an amount of usually 0.1 to 20 parts by weight, preferably 0.2 to 1 part by weight, based on 100 parts by weight of the toner binder.
It is used in the range of 0 parts by weight.

The release agent is used for the purpose of improving the releasability at the time of fixing with a hot roll. Examples of such a release agent include low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, and the like. Waxy substances such as paraffin wax. This release agent is usually used in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the toner binder. As the fluidizing agent, for example, inorganic fine particles having a particle size of several tens of nm, specifically, colloidal silica, alumina, titanium oxide, zinc oxide, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, Examples include titanium nitride, zirconium nitride, magnetite, molybdenum disulfide, aluminum stearate, magnesium stearate, and zinc stearate. This fluidizing agent is a silane-based, titanium-based coupling agent,
Hydrophobizing treatment may be performed with a higher fatty acid, silicone oil, surfactant or the like. These fluidizing agents are used in an amount of usually 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the magnetic toner particles (total of the above components). The magnetic one-component toner of the present invention comprises:
For example, it can be prepared by the following method. First,
Toner binder, magnetic powder and optionally used,
After dry blending each component except the fluidizing agent, melt-knead, then coarsely pulverized, finally finely pulverized by a jet pulverizer or the like, and further classified for particle size control, (A Component (B) has a volume average particle diameter of 4 to 10 μm, and component (B) has a volume average particle diameter of 14 to 25 μm.
Are prepared respectively. At this time, for the purpose of reducing industrial waste, it is preferable to reuse the fine powder generated in the toner classification step as a kneading raw material for the toner. Next, 1.0 to 7.0 parts by weight of the coarse magnetic toner of the component (B) is added to 100 parts by weight of the fine magnetic toner of the component (A), and the mixture is homogeneously mixed. Is added in a predetermined amount, and the mixture is further homogeneously mixed to prepare the magnetic one-component toner of the present invention having the above-mentioned particle size characteristics (particle size distribution). The magnetic one-component toner of the present invention thus obtained has a sufficient image density and can form an image capable of sharply reproducing fine lines such as characters. Further, since fine lines can be sharply reproduced, the amount of toner consumption can be suppressed to a small value.
Further, since the fluidity is improved, aggregation of the toner and formation of a bridge in the developing device are less likely to occur, and as a result, an image having good image quality without image unevenness can be obtained. Although the toner cartridge is repeatedly used from the viewpoint of resource saving, the magnetic one-component toner of the present invention can be suitably used as a toner for filling the cartridge for repeated use.

[0008]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, various characteristics in each example were determined by the following methods. (1) Particle Size Distribution of Toner A volume distribution and a number distribution of toner particles are measured using a Coulter Multisizer II (manufactured by Coulter Inc.) using an aperture tube having a diameter of 100 μm. (2) Bulk specific gravity Measured according to JIS 5101. (3) Image Density Using a commercially available laser printer equipped with a magnetic one-component developing device, a print test for continuously printing 14,000 test patterns is performed. The image density is measured using a Macbeth densitometer (manufactured by Macbeth) until the 14000th sheet, and the average of the measured values is taken. (4) Fine line sharpness In the above print test, the fine line portion is observed with a loupe. (5) Toner Consumption In the above print test, the amount of toner used for printing 14,000 sheets is measured from the weight of the developing device before and after the print test, and the number of printed sheets per 1 g of toner is calculated.

Example 1 100 parts by weight of a styrene / butyl acrylate copolymer (copolymer weight ratio 80/20, weight average molecular weight 250,000), magnetic iron oxide 90 parts by weight, azo metal complex 3 parts by weight and low molecular weight polyethylene 4 After the weight parts were mixed well with a blender, they were kneaded with a twin-screw kneading extruder set at 150 ° C.
After cooling the obtained kneaded material, it was coarsely pulverized using a feather mill. Next, after pulverizing with a jet mill, the mixture is classified with an airflow classifier to obtain a volume average particle size of 8.7 μm.
m of fine particle magnetic toner (A) and volume average particle diameter of 15.1
μm coarse particle magnetic toner (B) was obtained. Next, 5.0 parts by weight of the magnetic toner (B) is added to 100 parts by weight of the magnetic toner (A), and then 0.8 part by weight of hydrophobic colloidal silker is added to 100 parts by weight of the total amount. Was added and mixed with a Henschel mixer to prepare a magnetic one-component toner. Table 1 shows the particle size properties of the magnetic one-component toner and the bulk specific gravity as an index of the fluidity of the toner. Next, the magnetic one-component toner prepared as described above is filled in a reusable cartridge and applied to a commercially available printer “HP Laser Jet8000” (manufactured by Hewlett-Packard Company), and the image density, fine line sharpness and toner The consumption was determined. Table 1 shows the results. Comparative Example 1 The procedure of Example 1 was repeated, except that the magnetic toner (B) was not used. Table 1 shows the physical properties and properties of the toner. Comparative Example 2 The procedure of Example 1 was repeated, except that 10.0 parts by weight of the magnetic toner (B) was used. Table 1 shows the physical properties and properties of the toner.

[0010]

[Table 1]

[Note] The amount of the magnetic toner (B) is based on 100 parts by weight of the magnetic toner (A). As can be seen from Table 1, the bulk specific gravity increases as the added amount of the coarse particle toner (B) increases. That is, the fluidity was improved. Further, the magnetic one-component toner of the present invention (Example 1) has good image density, fine line sharpness, and toner consumption. In contrast, Comparative Example 1
Has good image density, but is inferior in fine line sharpness and toner consumption compared to the first embodiment. In Comparative Example 2, although the toner consumption was good, the image density and the fine line sharpness were inferior to those in Example 1.

[0012]

According to the magnetic one-component toner of the present invention, an image having a sufficient image density and capable of sharply reproducing fine lines such as characters can be obtained, the toner consumption can be suppressed low, and the fluidity of the toner can be reduced. And the effect that the aggregation of toner and the formation of a bridge in the developing device hardly occur.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazushi Masaki 1630-8 Takatsu, Mitsu-cho, Mitsu-gun, Okayama Prefecture F-term in IMEX Okayama Plant (reference) 2H005 DA05 EA05 EA07 FA06

Claims (3)

[Claims] 1. A fine particle magnetic toner having a volume average particle diameter of 4 to 10 μm and a coarse particle magnetic toner having a volume average particle diameter of 14 to 25 μm per 100 parts by weight thereof.
What is claimed is: 1. A magnetic one-component toner having a particle size distribution of a two-ridge structure including parts by weight, having a volume average particle size of 5 to 11 μm and a particle size of 5 μm.
m is 30% by number or less and the particle size is 16μ.
A magnetic one-component toner, wherein the content of particles having a particle size of m or more is 2.1 to 4.0% by volume. 2. The composition of a component (A) fine particle magnetic toner,
2. The magnetic one-component toner according to claim 1, wherein the composition of the coarse magnetic toner of the component (B) is substantially the same. 3. The magnetic one-component toner according to claim 1, which is used as a toner for filling a reuse cartridge.