JPH0335661B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a toner for an electrophotographic dry developer, and an object of the present invention is to prevent deterioration of its characteristics. Conventionally, there have been two-component electrophotographic developers in which toner particles and carrier particles are mixed to develop an electrostatic image, such as a cascade development method or a magnetic brush development method, and a so-called one-component development method consisting only of toner particles. A method of developing an electrostatic charge image using an agent is known. When any of the above-mentioned developers is repeatedly developed, for example, an electrostatic latent image on the same electrophotographic photoreceptor, the binder used in the toner particles on the photoreceptor or carrier Colorants and the like can accumulate and impair the sensitivity of the photoreceptor, and can also cause undesirable stains on the resulting copies.
There was a drawback that the charging characteristics of the toner particles changed. Therefore, various types of developers have been proposed in which abrasive particles and the like are added and mixed with the developer. For example, toners in which alkylated silane is added, fatty acid metal salts and colloidal silica are added, phthalic acid and its salts are added, and crosslinked polyvinylidene fluoride powder is added are known. . However, when these developers are used continuously, hard fine powder may damage the surface of the photoreceptor or accumulate on the carrier surface due to electrical force, reducing its original triboelectric charging ability. This gave rise to a new problem of impairing the durability of the steel. It is also known to improve the durability of the developer by adding a fluorine-containing surfactant to the toner. The present invention was developed based on the above points, and as a result of various studies, it was found that the carbon black powder contained in the toner has poor weather resistance due to its water absorption properties, and is easily affected by the temperature and humidity of the environment. It has been found that the carbon black in this toner has a negative effect on water, and the present invention was developed in an attempt to eliminate water adsorption and improve the weather resistance of the toner by making the carbon black in the toner water repellent. That is, the present invention relates to the general formula, Rf-( _CH2 ) _o -X or (RfO)m-Ar-Xw (where n=0 to 9, m=1 to 3, w=1 to 3 Rf: alkyl group (A fluorinated carbon group in which at least one hydrogen in an atomic group consisting of , alkenyl group, or aryl group is substituted with fluorine. Ar: Alkyl group or aryl group. X: Carboxyl group, sulfonic acid group, or hydroxyl group.) The gist of the present invention is to provide a toner for an electrophotographic dry developer, which is characterized in that it contains carbon black that has been surface-treated with an organic acid having a carbon fluoride group represented by the following formula. Examples of compounds corresponding to the above general formula include:
RfCOOH, _{RfCH2CH2COOH ,}

【formula】

【formula】

[Formula] −COOH,

【formula】

[Formula] RfSO ₃ H

【formula】

【formula】

[Formula] etc. Such compounds are surfactants and have a resistance of 10 ⁷ Ωcm.
Since the surface energy is as low as 30 dynes/cm or less, it does not impair the fluidity of the toner and improves weather resistance. Next, examples will be described. Example 1 After immersing 20 parts by weight of carbon black fine powder (trade name Carbon Black MA-100, manufactured by Mitsubishi Chemical Corporation) in 1000 parts by weight of a 0.1% methanol solution of an organic acid represented by C ₉ F ₁₇ COOH. The mixture was taken out and methanol was evaporated to obtain fine carbon black powder used in the present invention. 15 parts by weight of this fine carbon black powder and 85 parts by weight of methyl methacrylate resin were kneaded, placed in a powder frame, and classified to obtain a toner having an average particle size of 10 μm. This toner and EFV iron powder (manufactured by Nippon Tetsuko Co., Ltd.) were mixed and stirred in a ball mill for 1 hour to prepare developer A. On the other hand, for comparison, developer B was prepared in the same manner as in Example 1 using untreated fine carbon black powder. After the developers A and B were conditioned for 4 hours in an atmosphere with varying relative humidity, changes in the amount of charge were measured using a blow-off device. The results are shown in Table 1. It was found that developer A exhibits significantly less decrease in charge amount at high humidity than developer B.

[Table] Example 2 0.1% of organic acid expressed as C ₉ F ₁₇ CH ₂ CH ₂ COOH
After immersing 20 parts by weight of carbon black fine powder (trade name: Carbon Black #44, manufactured by Mitsubishi Kasei Corporation) in 1000 parts by weight of methanol solution, the methanol was evaporated by leaving it for 1 hour to prepare the carbon used in the present invention. A fine black powder was obtained. 10 parts by weight of this carbon black fine powder and 90 parts of epoxy resin (trade name Epicoat 1004, manufactured by Ciel)
Knead the parts by weight, use a powder frame, and classify to obtain an average particle size of 10 μm.
I got the toner. This toner and average particle size 100μm
spherical iron powder (trade name: SF-100, manufactured by Shinto Blater Co., Ltd.) and stirred for 1 hour in a ball mill to prepare developer C. When the charge amount of this developer C was measured, it was -25.6 μc/g. Also, 30℃, 90
% atmosphere for 4 hours, the amount of charge was measured again, and it was -25.2 μc/g, with almost no change. On the other hand, for comparison, a developer D was prepared in the same manner as in Example 2 using untreated carbon black fine powder. The amount of charge of this developer D is -
It was 25.5μc/g. In addition, after 4 hours of humidity control in a 90% atmosphere at 30℃, the amount of charge was measured again.
It had decreased to 12.5μc/g. Example 3

In 1000 parts by weight of a 0.1% methanol solution of an organic acid represented by the formula,
30 parts by weight of carbon black fine powder (trade name: Asahi HS-500, manufactured by Asahi Carbon Co., Ltd.) was immersed and left for 3 hours, and then methanol was evaporated to obtain carbon black fine powder of the present invention. 20 parts by weight of this carbon black fine powder and 80 parts by weight of polyester resin (trade name: Atlas 382A, manufactured by Kao Atlas Co., Ltd.) were kneaded.
The powder was classified using a powder frame to obtain a toner having an average particle size of 10 μm.
This toner and spherical iron powder with an average particle size of 100 μm (product name
Developer E was prepared by mixing and stirring SF-100 (manufactured by Shinto Breter Co., Ltd.) at 20° C. in a 65% atmosphere. When the amount of charge of this developer E was measured, -
It was 27.8μc/g. Similarly, a developer E' was prepared by mixing and stirring in a 90% atmosphere at 30 DEG C., and the amount of charge was measured, and it was found to be -27.6 .mu.c/g. In other words, it was found that the amount of charge hardly changes depending on the atmosphere in which the developer is prepared. On the other hand, for comparison, a developer F was prepared in the same manner as in Example 3 using untreated carbon black fine powder. The amount of charge when fabricated at 20℃ in a 65% atmosphere was -27.5μc/g,
The amount of charge when fabricated at 30℃ in a 90% atmosphere is -
It was 14.3 μc/g, which was a significant decrease. Example 4 30 parts by weight of carbon black fine powder (product name: Carbon Black Printex U, manufactured by Degussa) was immersed in 1000 parts by weight of a 0.1% ethanol solution of an organic acid represented by C ₉ F ₁₇ SO ₃ H, and left overnight. The sample was taken out and the ethanol was evaporated to obtain the carbon black fine powder of the present invention. 20 parts by weight of this carbon black fine powder and 80 parts by weight of styrene-acrylic copolymer were kneaded, powdered, and classified to obtain a toner having an average particle size of 10 μm. After conditioning this toner in a 65% atmosphere at 20℃ for 4 hours, it was mixed with the same spherical iron powder as in Example 2, which was also conditioned for 4 hours in a 65% atmosphere at 20℃.
A developer G was prepared by mixing and stirring in a 65% atmosphere at ℃. The amount of charge of this developer G was -25.6 μc/g. In addition, developer G' was prepared by changing the above atmospheric conditions to 30°C and 90%, and the amount of charge was measured.
It was found that there was almost no change at 25.3μc/g. On the other hand, for comparison, a developer H was prepared in the same manner as in Example 4 using untreated fine carbon black powder. The amount of charge in 20, 65% atmosphere is -25.5μc/g
On the other hand, at 30℃ and 90% atmosphere, -
It was 12.4 μc/g, which was a significant decrease. As is clear from the above, the toner of the present invention has extremely excellent weather resistance and is useful for use in electrophotographic dry developers.

Claims (1)

[Claims] 1 General formula Rf-(CH ₂ ) _o -X or (RfO) _n -Ar-Xw (where n = 0 to 9, m = 1 to 3, w = 1 to 3 Rf: alkyl A fluorinated carbon group in which at least one hydrogen in an atomic group consisting of a group, an alkenyl group, or an aryl group is substituted with fluorine. Ar: an alkyl group or an aryl group. X: a carboxyl group, a sulfonic acid group, or a hydroxyl group. ) A toner for an electrophotographic dry developer, characterized in that it contains carbon black whose surface has been treated with an organic acid having a fluorinated carbon group represented by: