JPS6019157A - Carrier for electrostatic latent image developer - Google Patents

Abstract

PURPOSE:To obtain a developer superior in reproducibility of solid parts and halftone, and not deteriorated in image quality by long time copying by forming a coating material obtained by adding a substance of high dielectric constant on the surface of a carrier core. CONSTITUTION:A carrier is prepared by coating a carrier core material made of iron, steel, aluminum, brass, glass, or the like with a coating material obtained by adding a substance of high dielectric constant, such as barium titanate, KNa tartarate, lead zirco titanate ceramics into a material of high resistance, such as polymethacrylate or polystyrene, in an amt. of 5-50wt% based on the coating material. A developer obtained by mixing said carrier with a toner is good in reproducibility of thin lines, solid parts and halftone, and long in life.

Description

Detailed Description of the Invention Technical Field This defense relates to a carrier for a developer used to visualize an electrostatic latent image formed by electrophotography, electrostatic recording, electrostatic printing, or the like. .

BACKGROUND OF THE INVENTION So-called two-component dry developers consisting of a mixture of carrier particles and toner particles are well known. In this two-component dry developer, minute toner particles are held on the surface of relatively large carrier particles by the electric force generated by the friction of rain particles, and when brought close to the electrostatic latent image, the electrostatic latent image The attraction force on the toner particles in the direction of the latent image due to the electric field formed by the toner particles overcomes the bonding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered to the electrostatic latent image, and the electrostatic latent image is visualized. It is something that The developer is used repeatedly while replenishing the toner consumed by development.

Usually, gearia particles are made by using a coated carrier whose surface is coated with resin, iron, ferrite, etc. as is.
! There are different carriers, each with their own advantages and disadvantages.

For example, carriers coated with styrene/methacrylate copolymers, styrene polymers, tetrafluoroethylene copolymers, silicone resins, etc. generally have high resistance due to the coating material itself, which increases the resistance of the developer, resulting in Although it has excellent reproducibility of fine lines, edge effects occur in solid areas, making it difficult to reproduce solid areas and halftones such as photographic originals, and the development bias effect tends to cause scratches and background smudges. There are drawbacks such as.

In comparison, uncoated Kitaria has a relatively low resistance, so although it has excellent reproducibility of solid areas and halftones, it has poor reproducibility of fine lines, and it also has problems such as developing bias leakage and photoreceptor damage. It has drawbacks such as easy attachment of carrier particles.

However, coated carriers have many advantages over uncoated carriers other than image quality, such as preventing toner from becoming spent and imparting triboelectric charging to toner by coating with a low surface energy substance.

Therefore, even if the material is coated with a material having a moderately high resistance, a coating main layer with good reproducibility of solid areas and halftones is required, but there has been no coating main layer that can satisfy both of these characteristics.

However, the present inventors have discovered that the reproducibility of solid areas and halftones is not determined only by the resistance of the developer, but is closely correlated with the dielectric constant of the developer.

In other words, a developer using a carrier with a high dielectric constant has excellent solid area and halftone reproducibility, whereas a developer using a carrier with a low dielectric constant has poor solid area and halftone reproducibility. .

However, in general, dry two-component coated carriers have a relatively low dielectric constant, and as the dielectric constant increases, the resistance decreases, making it extremely difficult to create a developer with a high dielectric constant and high resistance. .

Purpose The present invention provides a developer that has excellent solid area reproducibility and halftone reproducibility even when using a developer whose carrier surface is coated with a high-resistance substance, and which does not deteriorate image quality even after long-term use. This is what we provide.

Structure The present invention is a dry two-component carrier coated with a high-resistance material, and a carrier for an electrostatic latent image developer, characterized in that the high-resistance material contains a high dielectric constant material.

The present invention will be described in more detail below. Examples of the high dielectric constant material used in the present invention include barium titanate, potassium sodium tartrate, glycine sulfate, and lead zircotitanate ceramics. The amount of the high dielectric constant material added is preferably 5 to 50 parts by weight based on the coating material, preferably 10 to 30 tons.
This is the E m section. In addition, most of the conventional coating materials can be used as the high-resistance material to be coated, such as styrene/methacrylate copolymer, styrene polymer, tetrafluoroethylene copolymer, silicone resin, epoxy resin, polyester resin, etc. However, it is easily understood from the essence of the present invention that other 8-resistance materials can also be used.

In the present invention, the carrier surface coated with a high-resistance substance has an average particle size of 20 to 1000 μm, IF or 50 μm.
~500μ Kobal 1-1 Conventionally used materials such as non-metals such as iron, steel, nickel, zinc, aluminum, brass, and glass, metals, and metal alloys can be widely used. As a coating method for high-resistance materials, the high-resistance materials are dissolved in a solvent,
It may be applied to the surface of the core material by conventionally known means such as a spraying method. ' To add a high dielectric constant substance to the high resistance substance, it is sufficient to add it to a high resistance substance solution, disperse it with an appropriate mixer, and apply it on the surface of the carrier.

The toner used with the carrier of the present invention is one obtained by a conventionally known method, and specifically, a resin component and a coloring agent such as carbon black, which is usually necessary for forming a visible image, are thoroughly mixed. It is obtained by kneading it in a hot roll mill, cooling it, solidifying it, then crushing it and classifying it.

It is preferable that the amounts of the main 1-silica and 1-toner used are such that the toner particles adhere to the silicone resin surface of the toner particles and occupy 30 to 90% of the surface area thereof.

Examples will be described below.

Example 1 After dispersing a high-resistance substance solution with the following formulation for 30 minutes using a homomixer, the dispersion was coated on the surface of 100μ iron oxide powder 5K (+) using a fluidized bed coating device to form a high-resistance substance coating. I got a career.

Meltyl methacrylate polymer 37.5g High purity barium ditanate (+-IPBT-1 Fuji Titanium Industries) 12.
5g toluene 1450g The dielectric constant of the carrier particles is determined by filling a cell with an electrode area of 20C1 and an electrode gap of 11t2mm, and applying the IK
Applying Hz AC electrolysis and measuring the dielectric constant when IC is applied,
Further, when the resistance value of the same cell was measured after 100V was applied, the following values were obtained. Also shown are the dielectric constant and resistance values of uncoated carrier, Kyrelia that does not contain barium titanate.

As shown in the table, the carrier of the present invention has a high resistance and a large dielectric constant.

To these three types of carriers, toner (styrene-n-butyl methacrylate-18), 3 parts by weight of metal complex salt type dye,
When 3% by weight (10 parts by weight) of carbon black was mixed, a developer was prepared, and copying was performed, the following results were obtained.

This shows that the carrier of the present invention is excellent in fine line reproducibility, solid area reproducibility, and halftone reproducibility. In addition, an experimental machine (uses selenium photoreceptor, repeats charging, exposure, development, transfer, and static elimination 30 times per minute) using the developer of the present invention
I copied C 100,000 times, but there was almost no change in image quality.

Example 2 After dispersing a high resistance substance solution with the following formulation in a homomixer for 30 minutes, the dispersion was mixed into 120μ Ferray 1 to Carrier 7 KO.
coated on the surface using a fluidized bed coating device,
A carrier coated with a high resistance material was obtained.

Styrene polymer 52.5111 High purity barium ditanate (+-I P B T -1 Fuji Titanium Industry) 17.
5g1 Heluene 1430 (1) The dielectric constant and resistance of this carrier, uncoated Kytyria, and a carrier not containing barium titanate were measured in the same manner as in Example 1.

As shown in the table, the carrier of the present invention has a high resistance and a large dielectric constant.

Toner was mixed with these three types of carriers in the same manner as in Example 1 to prepare a developer, and copying was performed with the following results.

This shows that the carrier of the present invention is excellent in fine line reproducibility, solid area reproducibility, and halftone reproducibility. or,
Copies were made 100,000 times in the same manner as in Example 1 using the developer of the present invention, but there was almost no change in image quality.

Example 3 After dispersing a high-resistance substance solution with the following formulation for 30 minutes using a homomixer, the dispersion was coated on the surface of 100μ iron oxide powder 5K ( ) using a fluidized bed coating device to coat the high-resistance substance. Get a career.

Methyl methacrylate polymer 37.5 (] Lead silcondethanate ceramic fine powder (Pb Ti 03 , Pb Zr 03 ) 12.
50 Toluene 1450 g The dielectric constant and resistance of the Ky17ia, the uncoated Ky17ya, and the carrier not containing the lead silcondetanate ceramic fine powder were measured in the same manner as in Example 1.

As shown in the table, the Kyrelia of the present invention is a carrier with a high resistance and a large dielectric constant.

Toner was mixed with these three types of carriers in the same manner as in Example 1, a developer was prepared, and copying was performed.However, the following results were obtained.

It can be seen that the image quality, solid area reproducibility, and halftone reproducibility are both excellent. Also, using the developer of the present invention, the same procedure as in Example 1 was carried out.
I copied it 00,000 times, but there was almost no change in image quality.

Effects As explained above, the carrier of the present invention is used together with toner to develop electrostatic latent images, and has excellent reproducibility of fine lines, solid areas, and halftones, and also has no change in image quality even after long periods of copying. A duplicate image is obtained.

Patent applicant Rico Co., Ltd. Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (1)

[Claims] A carrier for an electrostatic latent image developer, characterized in that a dry two-component carrier coated with a high resistance material contains a high dielectric constant material in the high resistance material.