JPH0289064A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve flowability, environmental stability, filming preventive effect, effect of eliminating thickening of characters, offset preventive effect, cleanability and electrostatic charge stability by internally adding hard fine powder which does onto contain particles of large grain sizes and externally adding hydrophobic hard fine powder which is small in grain size to the toner. CONSTITUTION:The hard fine powder which has 0.3 to 1mum volume average grain size and does not contain the particles larger than 5mum grain size is internally added to the toner and the hydrophobic hard fine powder having <=0.3mum volume average grain size is externally added thereto. The hard fine powder which has 0.3 to 1mum volume average grain size and does not contain the particles larger than 5mum grain size is stable in electrostatic charge quantity, narrow in electrostatic charge quantity distribution, less in the fluctuation of the resistance and excellent in polishing effect. The hard fine powder having <=0.3mum volume average grain size sufficiently maintains the flowability. The flowability, environmental stability, filming preventive effect, effect of eliminating thickening of characters, offset preventive effect cleanability and electrostatic charge stability are improved in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing toner in an electrophotographic system,
More specifically, the present invention relates to a toner for developing electrostatic images used in electrophotography, in which a thin layer of toner is formed on a toner conveying member and development is performed to obtain a high quality image.

[Conventional technology] The dry developing method used in electrophotography, electrostatic recording, etc.
There are methods that use a two-component developer consisting of toner and carrier, and methods that use a one-component developer that does not contain carrier. The former method allows relatively stable and good images to be obtained, but it is difficult to obtain images of constant quality over a long period of time because carrier deterioration and fluctuations in the toner to carrier mixing ratio are likely to occur. Additionally, there are difficulties in maintaining the device and making it more compact. Therefore, the latter method using a one-component preservative, which does not have these drawbacks, is attracting attention.

By the way, in the - component toner, it is possible to improve fluidity, prevent filming on photoreceptors, etc., adjust electrical properties such as resistance, etc.
Hard fine powders such as titanium oxide, silicon oxide, silicon carbide, and aluminum oxide are added internally or externally for environmental stabilization, etc., but it is necessary to satisfy all the required characteristics. There was no.

For example, as the fluidity is improved, the triboelectric charging performance decreases, and a thin layer may not be sufficiently formed on the toner transporting member, resulting in a decrease in image density.

In addition, techniques for obtaining high fluidity by surface-treating the hard fine powder are disclosed in Japanese Patent Application Laid-Open No. 59-52255, but these are not satisfactory in all respects. There wasn't.

Among hard fine powders, those with a relatively large particle size have excellent polishing effects, prevent filming on photoreceptors, etc., and have the effect of adjusting resistance, etc., but when this is added internally to toner, The toner has poor compatibility with the resin, resulting in poor dispersion, resulting in a wide distribution of toner triboelectric charge, and may cause scumming, transfer handling, etc.

If this is externally added to the toner, the content in the toner may change due to long-term use, and the polishing effect may be impaired.

Among hard fine powders, those with a relatively small particle size have the effect of improving the fluidity of the toner, but if they are added internally to the toner, they may cause filming on the photoreceptor, damage to the cleaning member, etc. May cause a decrease in fluidity in the environment.

[Problems to be Solved by the Invention] The present invention provides a one-component development system for electrophotography in which a thin layer of toner is formed on a toner transport member and developed to obtain a high-quality image. The problem to be solved is to obtain a toner that has improved properties, anti-filming effect, anti-texture thickening effect, anti-offset effect, cleanability, and charging stability.

[Means for Solving the Problems] According to the present invention, a hard fine powder having a volume average particle diameter of 0.3 to 1 μm and containing no particles larger than 5 μm is internally added, and the volume average particle diameter Provided is a toner for developing an electrostatic image, characterized in that a hydrophobic hard fine powder having a diameter of 0.3 μm or less is externally added.

In the present invention, the hard fine powder (I) having a volume average particle size of 0.3 to 1 μm and containing no particles with a particle size larger than 5 μm has a stable charge amount, a narrow charge amount distribution, and little variation in resistance. Contributes to providing toner with excellent polishing effect. This hard fine powder (I) is preferably treated to improve its compatibility with the resin, since this improves the dispersibility in the resin and provides a homogeneous toner.

Then, it is further hydrophobized and the volume average particle size is 0.3μ.
The hard fine powder (I) having a particle diameter of m or less maintains sufficient fluidity and contributes to providing a toner that is stable even under environmental conditions. If only the hard fine powder (I) is added internally, the fluidity will be insufficient, and if only the hard fine powder (II) is added externally, the polishing effect will be small and the effect of preventing filming on the photoreceptor etc. will be insufficient. It is enough.

Treatments for improving the compatibility of the hard fine powder (I) with resins include, for example, treatment with various surface treatment agents such as titanium-based coupling agents, as is known in the art.
It can be kneaded in advance with a small amount of binder resin for toner or dehydrated by heating, but is not limited thereto.

The treatment for improving the hydrophobicity of the hard fine powder (II) is known in the art, for example, as described in Japanese Patent Application Laid-Open No. 59-52.
The surface treatment can be performed using alkyltrialkoxysilanes described in Japanese Patent Application No. 255, etc., but the surface treatment is not limited thereto.

When the hard fine powder (I) of the present invention is internally added to the toner,
The amount added is 0.5 to 100 parts by weight of the binder resin.
Appropriate is 30 ω parts, preferably 5 to 20 ω parts.

If the amount is less than 0.5 parts by weight, a sufficient polishing effect may not be obtained, and filming may occur on the photoreceptor, etc. 30
If the amount used exceeds 4 parts, the toner's inherent triboelectric charging performance may be impaired or fixing offset may occur. The volume average particle size of this hard fine powder (I) is 0
．． It is essential that the particle size is between 3 and 1 μm and does not contain particles larger than 5 μm. Particles with a volume average particle size of less than 0.3 μm will not provide a sufficient polishing effect, and particles with a particle size of more than 5 μm may impair the original function of the toner.

When the hard fine powder (II> of the present invention is externally added to the toner,
The amount added is 0.05 to 100 parts by weight of toner.
5 parts by weight, preferably 0.1 to 3 parts by weight is suitable.

If it is less than 0.05 parts by weight, sufficient fluidity cannot be obtained, and 5
If the weight part is exceeded, the toner may be excessively coated, impairing the toner's original function, or causing filming on the photoconductor, etc.
This may cause toner scattering, etc. The volume average particle diameter of this hard fine powder (n) is preferably 0.3 μm or less. If the volume average particle diameter exceeds 0.3 μm, a sufficient flowability improvement effect may not be obtained.

Further, the toner of the present invention can be used in a known development process in electrophotography.

For example, it has a toner conveying member, a toner layer thickness regulating member,
After the toner is supplied onto the toner transport member, the toner is made into a thin layer through a toner layer thickness regulating member that is brought into pressure contact with the rotating surface of the toner transport member and regulates the layer thickness of the transported toner. It can be used in a one-component development method in which a latent image is developed by supplying the toner to a latent image carrier, but is not limited thereto.

[Example code] Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Styrene-n/butyl methacrylate copolymer 95 parts by weight Polypropylene wax 5 parts by weight Carbon black 6 parts by weight Negative polarity control agent
3 parts by weight Hard fine powder (1) treated to enhance resin dispersion effect (average particle size 0.5 μm) 10 parts by weight Hard fine powder (I) is made by treating commercially available silicon carbide with a titanium-based coupling agent. This is what was obtained. The above materials are mixed and melt-kneaded. After cooling, it was crushed and classified to obtain a toner having a particle size of approximately 5 to 30 μm.

Hard fine powder (■) (average particle size: 0.05 μm) silicon oxide that had been hydrophobized with octyltrimethoxysilane was mixed with the above toner, and after air sieving, a developer was prepared.

Example 2 Same as Example 1 except that cerium oxide (average particle size 1 μm) and alumina (average particle size 0.02 μm) were used instead of hard fine powders (I) and (II) in Example 1, respectively. A developer was obtained.

Comparative Example 1 Example except that in place of the hard fine powders (I) and (n) of Example 1, hard fine powders not treated to enhance the resin dispersion effect and hard fine powders not subjected to hydrophobization treatment were used. A developer was obtained in the same manner as in Example 1.

Comparative Example 2 Instead of mixing the hard fine powder (II) of Example 1 with the toner, the materials were kneaded together during melt-kneading, and after cooling, they were crushed and classified to obtain a developer in the same manner as in Example 1. Ta.

Comparative Example 3 Instead of melting and kneading the hard fine powder (1) of Example 1 with the material, it was mixed with the hard fine powder (■) after toner classification,
After wind sieving, use 1q of developer.

The various developers listed above can be used at room temperature and humidity (25°C, 65% RH), high temperature and high humidity (30°C, 90% RH), and low temperature and low humidity (1
Table 1 shows the results of copying tests conducted under various environmental conditions (0° C., 15% RH). In the table, ◯ indicates good, △ indicates slightly poor, and X indicates poor.

[Effects of the Invention] As is clear from the above description, according to the present invention, fluidity, environmental stability, filming prevention effect, text thickening elimination effect, offset prevention effect, cleaning performance, and charging stability are improved. Toner 17 for developing an electrostatic image is added.

Claims (1)

[Claims] A hard fine powder with a volume average particle size of 0.3 to 1 μm and no particles larger than 5 μm is added internally, and a hydrophobic hard fine powder with a volume average particle size of 0.3 μm or less is added externally. A toner for developing electrostatic images characterized by: