JPS63281173A - Carrier for dry developer images - Google Patents

Abstract

PURPOSE:To reduce electric resistance of the surface of a carrier and to enhance strength of adhesion to the coat layer of a carrier core material by forming the coat layer obtained by dispersing a conductive polymer into a resin on the surface of the carrier core material. CONSTITUTION:The coat layer to be formed on the surface of the carrier core material, such as iron, ferrite, or glass beads, usable as it is, is obtained by dispersing the conductive polymer, such as polymers prepared by doping poly-p- phenylene or polyphenylene sulfide with AsF5, into the resin, such as a silicone resin, fluororesin, or when needed, acrylic resin, a polyolefin resin, alone or in combination of some of them. Iron powder, ferrite or glass beads can be used as it is for a core material. Thus, electric resistance of the coat layer of the carrier is lowered and adhesion between the coat layer and the carrier core material to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a carrier for a dry developer, and more particularly,
The present invention relates to an improved carrier used in a dry two-component developer for developing electrostatic latent images in electrophotography, electrostatic recording, etc.

(Prior Art) A dry two-component developer conveys the toner to an electrostatic latent image by frictional charging of the toner and carrier, and develops the image, thereby creating a visible image. At this time, if the electrical resistance of the carrier is low, the carrier acts as a developing electrode, and the distance between the developing electrode and the surface of the latent image to be developed becomes close. This makes it possible to make faithful copies.

By the way, toner, which is one component of the developer, is consumed during development, but the other component, carrier, is hardly consumed during development and is used repeatedly, so there may be problems between the carriers or between the carrier and the developing device. (spent phenomenon, which causes deterioration of charging characteristics due to collision with various parts, adhesion or adsorption of toner and toner components to the carrier surface), making it impossible to obtain an image faithful to the original, and finally the developer You end up having to replace the whole thing.

Conventionally, in order to eliminate such deterioration phenomena, the surface of the carrier core material has been coated with a resin having excellent mold releasability. However, such a resin-coated carrier has a high electrical resistance, and as a result, it cannot be expected to function as a developing electrode, making it impossible to faithfully reproduce lines and solid areas.

In order to solve this problem, a carrier containing porous carbon black in the coating layer has been proposed (Japanese Patent Application Laid-Open No.
6-75659). However, this career
The adhesion between the coating layer containing porous carbon black and the carrier is insufficient, and with long-term use, the coating layer peels off, and the toner or some of the toner components adheres or adsorbs to the peeled part. There was a problem in that it caused a deterioration phenomenon (spent phenomenon).

(Purpose) The present invention has been made in view of the above points, and its purpose is to suppress the electrical resistance of the coating layer of the carrier and improve the adhesiveness between the coating layer and the carrier core material, so that it can be used for a long period of time. It is an object of the present invention to provide a carrier for dry type developer that can provide a faithful image to a document over the entire range.

(Structure) The present invention provides a carrier for a dry developer, characterized in that a coating layer formed by dispersing a conductive polymer substance in a resin is provided on the surface of a carrier core material.

Conductive polymer substances include polymers with a structure in which conjugated bonds are long and repeated, and which have a conductivity of metal or a value close to that of a metal, as well as those that have a conductivity of a semiconductor region in an undoped state. indicates AsF3.1
It also includes those exhibiting metal or near-metal conductivity by doping with a suitable dopant such as 1Br.

Specific examples of conductive polymer substances include a polymer in which poly-p-phenylene is doped with AsF3, a polymer in which polyphenylene selenide is doped with AsF3,
Polymer doped with 12 in poly(1,6-pentadiyne), As in poly(paraphenylene vinylene)
F3 doped polymer, poly-2,5 diene doped with 12, polybiphenylene doped with AsF3, polybiphenylacetylene doped with AsF3, polyacrylonitrile doped with 12, polyallylethyl Examples include a polymer in which copper is doped with 12, a polymer in which polyphenylene selenide is doped with AsF3, and polyberinaphthalene.

In the present invention, the resin for dispersing the conductive polymer substance (coating resin) used in the coating layer includes silicone resin, fluororesin, and, if necessary, acrylic resin, polyolefin resin, polychloride resin, etc. One or more types of vinylidene resin, phenol resin, epoxy resin, amino resin, polyamide resin, polyester resin, polyurethane resin, polycarbonate resin, etc. may be used.

The amount of the conductive polymer substance is preferably 1 to 80 parts by weight based on 100 parts by weight of the coating resin. Also, the thickness of the coating layer is 0.5
It is preferable to set it as μTrL~5 μm.

In addition, the carrier core material used in the present invention includes iron,
Conventionally known materials such as ferrite and glass beads can be used as they are.

To provide a coating layer on the carrier core material, a conductive polymer substance is dispersed in a coating resin liquid, the carrier core material is soaked in this dispersion liquid, the dispersion liquid is sprayed, or a fluidized bed method is used. There are various methods such as, but these are not particularly limited.

Further, the toner used in combination with the carrier of the present invention is not particularly limited, and commonly used toners can be used.

(Example) Next, the present invention will be further explained with reference to Examples.

First, production examples of the conductive polymer substance and toner used in the examples are shown below.

Preparation of conductive polymer 1 A. Preparation of conductive poly-p-phenylene In the presence of a small amount of water, aluminum chloride, copper dichloride and benzene were reacted in a nitrogen atmosphere at 35°C. After treatment with water and hydrochloric acid, a brown powder was obtained by washing with an aqueous NaOH solution and finally with water. The above was doped with AsF3 to obtain conductive poly-p-phenylene (sample A).

B. Production of conductive polyphenylene sulfide Add Na2S.9H20 to N-methylpyrrolidone, flow N2 gas, and heat to 160°C. After the water is dehydrated, add p-dichlorobenzene and heat in a stainless steel container at 250'C124.
After reacting for a time, the polymer was washed with water and acetone, dried, and then doped with AsF5 to obtain conductive polyphenylene sulfide (sample B).

C9 conductive poly-(1,6-hebutadiyne)! I! Luminium triisobutyl 10% in Dora dry box
Put hebutane solution and tetrachlorotitanium 10% hebutane solution into a reaction container, then remove from the dry box.
Flow N2 gas in a water bath. Dry hepta-1,6-diyne is dropped from the burette into the reaction vessel to initiate polymerization. After keeping it at 0℃ for 5 hours and reacting at room temperature for another 20 hours, methanol was added to decompose the product, a small amount of benzene was dissolved and reprecipitated from methanol to obtain a polymer, and doped with 2. Conductive poly(1,6
-heptidine) was obtained (sample C).

C9 Preparation of conductive poly(paraphenylene vinylene) Paraxylene bistriphenylphosphonium chloride and terephthalaldehyde are stirred in dehydrated alcohol, and an ethanol solution of lithium ethoxide is added dropwise to the reaction vessel. Filter the polymer precipitate, use benzene as a solvent, and extract and remove low molecular weight substances with a Soxhlet A.
Sample D) to obtain conductive poly(paraphenylene vinylene) by doping with SF5.

Production of Toner A mixture of the following formulation was heated and kneaded on two rolls, cooled, and then crushed and classified to produce a toner having a size of 5 to 20 μm.

Polystyrene (Esso D-125> 100 parts by weight Metallic dye (Hodogaya Chemical Spiron Black BH) 5 parts by weight Carbon black 5 parts by weight Example 1 A coating liquid was prepared according to the following formulation.

Silicone resin (Toray Silicone 5R240B) 10
0 parts by weight Sample A 15 parts by weight Toluene 1500 parts by weight 5 KFJ of oxidized iron powder with an average particle size of 100 μm was placed in a rotating disk type fluidized bed particle coating device, and while fluidized, the coating liquid of the above formulation was heated at 80°C. The coated material was taken out of the coating equipment and placed in a constant temperature bath.
The silicone film was cured by heating at 00° C. for 2 hours to obtain a carrier provided with a coating layer made of a conductive polymer dispersed in a resin.

The above toner and carrier were mixed so that the toner concentration was 3 wt% to prepare a developer. When the charge amount of the toner was measured by the blow-off method, it was found to be -25 μc/g, indicating that it was negatively charged. Continuous copying tests were carried out using this developer on a Ricoh copying machine FT6400, and the charge level after copying 100,000 sheets was measured at 120.
There was almost no deterioration at μC/9, and the image quality was no different from the initial one.

Place the developer at this point on a 350 mesh sieve,
Only the toner was removed with a cleaning machine, and the surface of the remaining carrier was observed under an electron microscope (hereinafter referred to as SEN), and it was confirmed that the coating layer covered the surface of the carrier core material neatly, unchanged from the initial stage. Note that the image quality was faithful to the original without any edge effect due to the addition of a conductive agent.

Examples 2 to 4 Tests were conducted in the same manner as in Example 1 except that the type of conductive polymer substance (conductive material) was changed. The results were as follows.

Example 5 The silicone resin in Example 1 was replaced with a methyl methacrylate polymer (approximately 50,000>509), and coating was performed by heating at 80° C. to obtain an MMA coating film.

When this carrier was tested in the same manner as in Example 1, the same results were obtained.

Example 6 A toner was prepared in the same manner as in Example 1 by replacing the toner example in Example 1 with a disazo pigment (Riono/L/Yellow FGNT, manufactured by Toyo Ink Co., Ltd.) using carbon black as a yellow toner. When tested, the same results as in Example 1 were obtained.

Comparative Example 1 Sample A in the carrier coat formulation of Example 1 was replaced with Ketjen Black εCDJ500 (Lion Akzo Co., Ltd.)
A coating film was obtained in the same manner as in Example 1, except that carbon was used as the carrier core material. Furthermore, when a developer was prepared in the same manner as in Example 1, the Q/M was -24 μc/g and FT-640.
When I made 100,000 continuous copies with 0 (manufactured by Ricoh) Q
/M was -13.5 μC/9. When the carrier after continuous copying of 100,000 sheets was observed using SEM in the same manner as in Example 1, it was confirmed that the coating layer on the carrier surface resembled fish scales and the carrier core material was partially exposed. did it. In addition, it was confirmed that the toner was partially spent in this area. This is considered to be the reason why Q/M decreased after 100,000 copies.

It was also found that as the Q/M decreased, toner scattering within the machine became more pronounced. Also, if you look closely at the image, the dirt on the background area has become noticeable.

(Effects) As is clear from the above explanation, the present invention provides a coating layer made by dispersing a conductive polymer substance in a resin on the surface of the carrier core material. The resistance can be kept low, and the conductive polymer material has excellent adhesion to the coating resin and core material, which improves the adhesion strength of the coating layer to the carrier core material. The coating layer is difficult to peel off even when pressure is applied, and a faithful image can be provided to the original for a long period of time.

Claims (1)

[Claims] A carrier for a dry developer, characterized in that a coating layer formed by dispersing a conductive polymer substance in a resin is provided on the surface of a carrier core material.