JPS6259966A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To form a thin toner layer to a uniform thickness so that substantial frictional electrostatic charge is generated by forming network structure of the fibers of a polytetrafluoroethylene on the surface of toner particles contg. a binder resin and coloring agent. CONSTITUTION:The toner contg. a polystyrene, chlorinated paraffin and other binder resins as well as carbon black, aniline black, iron oxide, crystal violet and other coloring agents and the powder of the polytetrafluoroethylene are put into a whirling blender and are agitated, by which the network structure is formed on the surface of the toner particles. The polytetrafluoroethylene with does not stick to the toner surface is then removed by using a classifier. The thin toner layer having the uniform thickness is thereby formed on a toner conveying member and the substantial frictional charge quantity is obtd.

Description

Description: TECHNICAL FIELD This invention relates to toners for developing electrostatic images, and particularly to toners for developing electrostatic images suitable for use in developing devices that form a uniform thin layer of toner on a toner transport member.

2. Description of the Related Art A method is known in which a toner is conveyed by a toner conveying member and an electrostatic latent image formed on a latent image carrier by the toner is visualized.

In this developing method, a one-component developer consisting only of toner or a two-component developer consisting of toner and carrier is generally used, but in particular, a -component developer (toner) is used, and the toner is a two-component developer (toner). When a material with high electrical resistance is used, the toner layer must be extremely thin because it is necessary to charge the toner with a developing device. This is because if the toner layer is thick, only the vicinity of the surface of the toner layer is charged, making it difficult to charge the entire toner layer uniformly.

In order to reduce the thickness of the toner layer, there is a method of controlling the thickness of the toner layer by pressing down the toner on the surface of a doctor blade or toner conveying member with a suppressing member, but this method uses toner made of a binder resin and a colorant. Because toner supply was unstable, a uniform thin layer of toner could not be obtained, and frictional charging was insufficient, only images with low image density and many background stains could be formed.

For this reason, a method was proposed in which fine powder with a particle size of 1/20 to 1/2 of the toner particles was mixed into the toner. There is a drawback that the thickness regulating member is partially worn out, and a uniform thin layer of toner is no longer formed.

An object of the present invention is to provide a toner for developing an electrostatic image that forms a thin toner layer with a uniform thickness on a toner conveying member and has sufficient frictional electrification.

Structure An object of the present invention to achieve the above object is to include a toner conveying member, a toner layer regulating member, and a toner replenishment auxiliary member, wherein the toner replenishing member, the toner conveying member, the toner layer regulating member, and the toner conveying member are respectively connected to each other. In a toner for developing an electrostatic image containing at least a binder resin and a colorant, which is used in a developing device that is in contact with the toner, a static image forming apparatus in which a network structure of polytetrafluoroethylene fibers is formed on the surface of the toner particles is used. Cover with toner for developing charge images.

The toner of the present invention appears to be in an agglomerated state, and when used as a toner for a conventional two-component developer, it has poor replenishment properties. However, in the developing device used in this invention, although the reason is not clear, the ability to replenish toner onto the toner conveying member is favorable, and even if the toner layer thickness regulating member is worn out, a unique feature is that a thin streak-like layer does not occur. A phenomenon is observed.

The network structure formation of polytetrafluoroethylene referred to in this invention is disclosed in JP-A-52-23941 and JP-A-53-14.
7541, in which toner and polytetrafluoroethylene powder are mixed in a Waring blender (Warli blender).
The polytetrafluoroethylene used to form a network structure, which can be easily formed by stirring in a blender), is E, I, Teflon KT manufactured by DuPont.
Suitable materials are those commercially available from Mitsui Polychemical Co., Ltd. under the trade names of TYPEIO1 and TYPE20.

As the binder resin for the toner, resins that have been widely used in electrophotographic toners, such as polystyrene,
Chlorinated paraffin, polyvinyl chloride, phenolic resin,
Polymers such as epoxy resins, polyesters, polyamides, polyacrylic acid resins, polyethylene, polypropylene, and copolymers thereof can be used alone or in combination of two or more.

As the colorant, for example, one or more pigments or dyes such as carbon black, aniline black, iron oxide, crystal violet, rhodamine B, malachite green, nigrosine, copper phthalocyanine, and azo dye can be used in combination. Furthermore, metal-containing complex dyes, zinc hexabutyl succinate, alkyl esters or alkylamides of naphthoic acid, nitrofumic acid, N,N--tetramethyldiaminebenzophenone, N,N'-tetramethylbenzidine, triazine, metal salicylates. Add one or two highly polar substances, such as complexes, which are called charge control agents in this field.
More than one species may be contained.

Next, an example of an apparatus suitable for using the toner of the present invention will be explained with reference to the drawings.

As shown in the drawing, the toner 6 contained in the toner tank 7 is forcibly brought to the sponge roller 4 (toner replenishment auxiliary member) by the stirring blade 5 (toner replenishment auxiliary member), and the toner is supplied to the sponge roller 4. be done. and,
The toner taken into the sponge roller 4 is transferred to the toner conveying member 2 as the sponge roller rotates in the direction of the arrow.
carried to the surface, rubbed, electrostatically or physically adsorbed,
The toner conveying member 2 rotates strongly in the direction of the arrow, and a uniform toner thin layer is formed by the toner layer thickness regulating member 3 (steel elastic blade) and is frictionally charged. After that,
The toner is transported to the surface of the electrostatic latent image carrier 1 that is in contact with or in close proximity to the toner transport member 2, and the latent image is developed.

Although the developing device has been described above, devices suitable for the toner of the present invention are not limited to the above-mentioned developing device.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Note that all amounts (parts) of each component described in Examples are parts by weight.

Example 1 Toner composition Polystyrene resin 90 parts Polyethylene
Part 4 C, 1, Pigment Blue 15
5 parts Nigrosine dye and Grosine EX (Orient Chemical) 1 part A mixture of the above composition was thoroughly stirred in a Henschel mixer.
After mixing, the mixture was heated and melted in a roll mill at a temperature of 130 to 140'C for about 30 minutes, cooled to room temperature, and the obtained kneaded product was crushed and classified to obtain a blue toner having a particle size of 5 to 15 μm.

Next, put this toner 100 () into a Waring blender, add fiberizable polytetrafluoroethylene (Teflon type 10 manufactured by DuPont) 20, rotate at maximum speed for 10 seconds, and then stop for 20 seconds. let me,
This was repeated 30 times to ensure sufficient dispersion. Then, polytetrafluoroethylene that did not adhere to the toner surface was removed using a classifier.

This toner was loaded into a developing device as shown in the drawing, and continuous copying was performed to test image quality and durability.

The electrostatic latent image was formed by charging the organic photoreceptor with −DC of 800 V and then exposing it to light.

As a result, the images were good, and there was no particular difference in image quality between the initial image and after 100,000 copies, and no streaky background stains or whitening occurred.

In addition, the wear of the toner layer thickness regulating member is minimal, and the toner
81 was also formed almost uniformly.

Comparative Example For comparison purposes, we conducted the same experiment using toner produced under the same conditions as in Example 1 except for the treatment with Teflon K, and found that there was almost no difference in image quality up to 10,000 sheets, but at around 15,000 sheets. Streak stains and whitening occurred.

Further, the toner layer thickness regulating member 3 (elastic blade) was frequently worn, and the toner layer became uneven.

Example 2 Toner composition Styrene-acrylic copolymer 87 parts Polypropylene 4.5 parts C.1, Pigment Red 8
1 5 parts C, 1, Pigment Red 48 3 parts Nigrosine dye and Groscine EX: Orient Chemical) 0.5 parts A mixture of the above composition was melt-kneaded in the same manner as in Example 1, then crushed and classified to produce a red color with a size of 5 to 15 μm. Got toner.

Next, 100 g of this toner was stirred with 2 g of polytetrafluoroethylene in the same manner as in Example 1.

When this toner was subjected to a continuous copying test in the same manner as in Example 1, the images were good, and no difference was observed between the initial image quality and the image quality after 100,000 sheets were continuously copied.
No drops occurred. Furthermore, toner replenishment was smooth and a uniform thin layer of toner was formed on the toner conveying member.

Example 3 Composition of toner Epoxy resin 84 parts Polypropylene 4 parts C1, Pigment Blue 15
2 parts C.1, Pigment Yellow 175 parts Stearyl methylbenzyl ammonium chloride 5 parts A toner was prepared and tested in the same process as in Example 1 using the raw material mixture having the above composition.The image was good and there were no streaks. There were no abnormal images such as dirt on the skin or white hair.

Example 4 Composition of toner Polyester resin 85 parts Carbon black 10 parts Nigrosine dye and Grosine EX (Orient Chemical) 5 parts A toner was made in the same process as in Example 1 using the raw material mixture with the above composition and tested. The image was good, with no streaky background stains or white spots.

Effects As explained above, the toner of the present invention forms a uniform thin layer on the conveying member even after long use, and is sufficiently triboelectrically charged, so that the quality of the formed image is excellent.

[Brief explanation of the drawing]

The drawing shows an electrostatic image developing apparatus suitable for using the toner of the present invention. 1... Electrostatic latent image carrier, 2... Toner transport member, 3
... Toner layer thickness regulating member, 4... Sponge roller, 5... Stirring blade, 6...
- Toner, 7... Toner tank.

Claims (1)

[Scope of Claims] Used in a developing device that includes a toner conveying member, a toner layer regulating member, and a toner replenishing auxiliary member, and in which the toner replenishing member and the toner conveying member, and the toner layer regulating member and the toner conveying member are in contact with each other. A toner for developing an electrostatic image containing at least a binder resin and a colorant, characterized in that a network structure of polytetrafluoroethylene fibers is formed on the surface of the toner particles. .