JPH0523433B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a developer, particularly carrier particles, for developing electrostatic latent images in electrophotography and electrostatic recording. Prior Art In electrophotography or electrostatic recording, an electrostatic latent image formed on a photoconductor or electrostatic recording medium is developed using a magnetic brush method, a cascade phenomenon method, etc. to form a toner image, and this toner image is transferred to paper. A copy is obtained by transferring to a transfer material such as. During this development, a carrier is used to impart a predetermined charge to the toner. Carriers are generally classified into coated carriers and non-coated carriers, and coated carriers are mainly used for the purpose of controlling chargeability and preventing toner adhesion. There are various properties required of this coat carrier, and particularly important properties include triboelectric charging properties, impact resistance, abrasion resistance, adhesion between the core material and the coating material, and uniformity of charge distribution. Traditionally, fluorinated vinyl polymers or acrylic polymers have been used as carrier coating materials, but although fluorinated vinyl polymers have excellent charging properties, they have poor adhesion to the core, and acrylic polymers have poor mechanical properties. Although it has excellent strength and adhesion to the core, it has drawbacks such as poor charging performance, mixed polarity charged toner, and slow charging speed. Also, the coated carrier was inferior to the uncoated carrier in reproducing solid areas and halftone areas. OBJECTS OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to improve the conventional drawbacks and provide a carrier that has excellent charging properties and excellent adhesion between the core and the coating material. Another purpose is to provide a carrier with good reproduction of solids and intermediate tones. Structure of the Invention The object of the present invention is to form the surface of the core material with the general formula (RO) _o Zn(Y) _4-o [where n is an integer from 0 to 3, R is a hydrocarbon group or a substituted hydrocarbon group, X represents a carboxylic acid residue having an amino group in the molecule. ] This can be achieved by using a carrier coated with a compound represented by the following or a condensate thereof. The coating material used in the present invention is a compound represented by the above general formula or a condensate thereof; for example, R is methyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, n- Amir,
selected from lower alkyl such as i-amyl, t-amyl, and X is an α-amino acid, a substituted or unsubstituted carboxylic acid having an amino group, such as glycine,
Alanine, valine, leucine, serine, threonine, cystine, proline, triproane, lysine, arginine, phenylalanine, histidine, β-alanine, r-aminobutyric acid, nicotinic acid, isonicotinic acid, anthranilic acid, m-aminobenzoic acid , p-aminobenzoic acid, etc. Various known core materials can be used as the core material used in the present invention, such as triiron tetroxide, iron sesquioxide, MnZn ferrite, NiZn ferrite, Ba
Examples include particles having a particle size of about 20 to 500 μm, such as ferrite, chromium dioxide, iron, nickel, cobalt, and glass beads. Further, particles in which magnetic powder is dispersed in a binder resin may be used as the core material. The carrier particles of the present invention can be obtained by surface-treating the core material described above with a coating material represented by the general formula described above, and forming a coating layer of the coating material on the surface of the core material by chemical bonding or adsorption. can. For surface treatment of the core material, for example, the core material is immersed in a solution in which the coating material is dissolved, followed by desolvation, drying, and high temperature treatment, or the core material is suspended in a fluidized bed and the coating material is treated. A method of spraying a solution, drying it, and further treating it at a high temperature can be used. These methods do not necessarily require high-temperature treatment, but from the point of view of improving adhesion,
It is better to process at 100-200℃. The coating amount of this coating material is preferably about 0.001 to 5 parts by weight, preferably about 0.01 to 2.5 parts by weight, based on 100 parts by weight of the core material. The carrier according to the present invention is used in combination with a toner. Various known toners can be used and are not particularly limited. Toner is carrier
It is mixed in an amount of about 1 to 20 parts by weight per 100 parts by weight. This developing agent consisting of carrier and toner is used to develop an electrostatic latent image formed on a photoreceptor or electrostatic recording medium, and various developing methods such as magnetic brush development method and cascade development method are applied. be able to. Effects of the Invention The carrier of the present invention has a core material coated with a coating material of a specific compound, and has various excellent effects. First of all, compared to conventional coated carriers, it has superior charging properties and uniformity of charge distribution, that is, the charging speed is significantly faster, and there is no charge decay or accumulation, which makes it easier to charge due to changes in temperature and humidity or after long-term use. It is also stable, and the charge distribution is sharp and does not contain charges of different polarity. Furthermore, the adhesion between the core material and the coating material is excellent, and the coating material does not peel off. A further noteworthy point is that the coating material according to the present invention has a relatively low resistance, and does not cause the deterioration of image quality in solid areas and halftone areas that is observed in conventional coat carriers. EXAMPLES The present invention will be specifically explained below using examples. Synthesis Example 76.6 parts (0.2 mol) of Zr(OC ₄ H ₉ ) ₄ was dissolved in 100 parts of Daiflon Solvent (Daikin Co., Ltd., trade name: fluorine-based solvent) and cooled to 10°C or lower. 24.6 parts (0.2 mol) of isonicotinic acid dissolved in 100 parts of Daiflon solvent was cooled to 15° C. or lower and added dropwise to the solution over 20 minutes with stirring. After the entire amount was added dropwise, the mixture was stirred at room temperature for 30 minutes. Then, heat to 60℃ and continue reaction for 30 minutes.
The solvent and the n-butanol produced were removed under reduced pressure. After substantially removing volatile substances at 10 mmHg and 60°C, 200 parts of Daiflon Solvento was added and dissolved to obtain 286.4 parts of a pale yellow transparent solution. The product is

It was [formula]. Example Core material with average particle size of 100 μm and resistance of 10 ¹⁰ Ωcm
A coating layer was formed on 100 parts by weight of the Ni-Zn ferrite particles by a fluidized bed coating method using a coating solution consisting of 0.1 part by weight of the solution of the synthesis example and 10 parts by weight of Daiflon solvent to obtain a carrier. This coat carrier had a resistance of approximately 10 ¹¹ Ωcm. Styrene/n- is added to 100 parts by weight of this carrier.
A developer was prepared by mixing 3 parts by weight of a toner with an average particle size of 12 μm consisting of 92% BMA copolymer and 8% carbon black. When this developer was stirred in a V-blender and its charging properties were examined, the saturation charging speed was very fast at 1 minute, and it contained no charges of different polarity. On the other hand, the conventional carrier coated with methyl methacrylate resin had a saturation charging speed of 10 minutes and had different polar charges. When copies were made using this developer, copies with excellent solid and halftone reproduction and little fog were obtained. There was no change in image quality even after 50,000 copies were printed, and the amount of charge was 14 μc/g. When the carrier surface was observed, there was no peeling of the coating material, no adhesion of toner, etc.

Claims (1)

[Claims] 1. A core material and the following general formula (RO) _o Zr(Y) _4-o [wherein, n is an integer of 0 to 3, and R is a hydrocarbon group or a substituted hydrocarbon group] , Y each represents a carboxylic acid residue having an amino group in the molecule. ] A carrier for electrostatic charge development, characterized in that it has a coating layer of a compound represented by the following formula or a condensate thereof.