JPH031164A - Carrier for dry processing developer - Google Patents

Abstract

PURPOSE:To obtain the carrier for developers having an excellent developer life and high-speed developability by incorporating fluoroplastic powder into a binder resin and specifying the existence ratio of the fluorine atoms in the entire atom of the carrier surface. CONSTITUTION:The fluoroplastic powder is incorporated into the binder resin and the existence ratio of the fluorine atoms in the entire atom of the carrier surface is adjusted to 6 to 30atomic%. The existence ratio of the fluorine atoms varies with the amt. of the fluoroplastic to be added, the degree of dispersion or flocculation, the process for production of the carrier, etc. A sufficient electrostatic charge quantity is imparted to the carrier and the resistance to surface contamination is improved by adjusting the above-mentioned ratio to 6 to 30 atomic%. The developer life at the time of the high-speed development is prolonged in this way.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the use of two-component developers for developing electrostatic latent images or magnetic latent images in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to constituent carriers, particularly magnetically dispersed carriers.

(Prior art) In electrophotography, a photoconductive substance such as selenium is used as a photoreceptor, an electrical latent image is formed by various methods, and toner is applied to this latent image by a magnetic brush development method or the like. A method of attaching and visualizing is generally adopted.

In this development step, carrier particles called carriers are used to impart an appropriate amount of positive or negative electricity to the toner. Various types of carriers have been developed and put into practical use.

(Problems to be Solved by the Invention) There are various properties required of the carrier, but particularly important properties include appropriate charging properties, impact resistance, abrasion resistance, developability, and developer life. I can do it.

Considering the above-mentioned required characteristics, the carriers used in the past still have problems that need to be improved, and no carrier that fully satisfies them is known.

For example, conductive carriers such as iron oxide powder have excellent solid developability, but are inferior in fine line developability, and require a special charge control agent to be included in the toner to extend life.

On the other hand, although coated insulators are excellent in terms of service life and reproducibility of thin wires, they have the disadvantage of poor reproducibility of solids. In order to overcome these drawbacks, a small particle size carrier in which magnetic fine particles are dispersed in a binder resin, a so-called carrier for microtoning, has been proposed and put into practical use.

However, due to the adhesion of the carrier to the photoreceptor, changes in the amount of charge at high and low humidity due to magnetic particles liberated on the carrier surface, and the difficulty of surface treatment, the lifespan may be drastically shortened. This makes extension difficult.

The main object of the present invention is to provide a new magnetic brush development carrier for use in electrophotography and electrostatic recording for the development of electrostatic latent images.

Another object of the present invention is to provide a magnetic brush developer carrier that imparts a high charge amount to toner and has excellent developer life and high-speed development performance.

(Means for Solving the Problems) The present invention provides a dry developer carrier containing a binder resin and a magnetic powder, in which the binder resin contains a fluororesin powder, and This is a carrier for a dry type developer, characterized in that the amount of fluorine atoms present is 6 to 30 atomic%.

(Function) The carrier of the present invention contains fluororesin powder in the binder resin and adjusts the amount of fluorine atoms in the total atoms on the carrier surface to 6 to 30 atomic%, so that the carrier is not supercharged. It is possible to improve the surface stain resistance, and to significantly extend the life of the developer during high-speed development. That is, it has been found that the amount of charge or life of the developer has no direct correlation to the fluororesin content in the carrier, but rather to the amount of fluorine atoms present among all atoms on the surface of the carrier. The amount of fluorine atoms present varies depending on the amount of fluororesin added, the degree of dispersion or aggregation, the method of manufacturing the carrier, etc. The amount of fluorine atoms on the surface of the carrier is 6ato
If it is less than mic%, a sufficient amount of charge cannot be applied to the carrier, and the life of the developer cannot be extended.

Furthermore, if fluorine is present in an amount exceeding 30 atomic percent, the amount of charge becomes too large and the image density decreases. Therefore, the abundance of fluorine atoms on the carrier surface is 6 to 30 at.
By setting i to omic%, the above problem is resolved.

As the fluororesin fine powder that can be used in the carrier of the present invention, polymers containing fluorine in the main chain, for example,
Homopolymers such as tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, monofluoroethylene, hexafluoropropylene, etc., or copolymerizable unsaturated polymers with the above monomers such as ethylene, propylene, butylene, vinylidene chloride, trifluoroethylene, and others. Examples include copolymers with bound gold-containing monofines.

Furthermore, as the binder resin that can be used in the carrier of the present invention, all general thermoplastic resins can be used, and specifically, styrenes such as styrene, chlorostyrene, and vinylstyrene: ethylene, propylene, etc. , butylene, imbutylene, and other monoolefins; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, and other vinyl esters; methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, Phenyl acrylate, methyl methacrylate,
α-methylene fat fat momo/carboxylic acid esters such as ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone, vinyl iso Examples include homopolymers or copolymers of vinyl ketones such as propenyl ketone. Particularly representative binder resins include polystyrene, styrene-alkyl acrylate copolymer, and styrene-alkyl methacrylate copolymer. Examples include styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-maleic anhydride copolymer. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, and waxes.

As the magnetic fine particles that can be used in the present invention, all commonly used ferromagnetic fine particles can be used. Specifically, triiron tetroxide, α-iron dioxide, various ferrite powders, Examples include chromium and various metal fine powders.

Good results are obtained when the proportion of magnetic particles constituting the key of the present invention is usually 30 to 95%, preferably 45 to 90%.

In addition to the above-described necking resin, magnetic particles, and fluororesin powder, the carrier of the present invention includes various resins, charge control agents,
Coupling agents, fillers and other fine powders can be added inside the carrier.

Methods for producing the carrier of the present invention include a method of kneading, pulverizing, and classifying with a heating melt mixing device such as Kneader 1/Eberly, and a method of spraying, cooling, and solidifying a kneaded material.

The average particle size of the carrier particles of the present invention is preferably 30 to 200 μI, rather than 10 to 400 μI, in view of the balance between developer life, carrier adhesion to the photoreceptor, and image quality.
It is appropriate to

The carrier thus obtained is mixed with toner and used as a magnetic plan developer for developing electrostatic latent images.

The toner is not particularly limited, and may be a chargeable toner in which a colorant is dispersed in a binder resin, which is used in ordinary electrophotography.

The amount of fluorine atoms present on the carrier surface is determined by JEOL (
Co., Ltd. X-ray photoelectron spectrometer JPS-80 (resolution aoo
eV) using the ESCA method (Electron 5p
Electroscopy for Chemical＾na
lysis).

X-rays are Mg/Al twin anode type Mg1253
．． 6eY was used, and ION' was accelerated at 30 mA.

The carrier was sampled into a pure AI container measuring 15 x 10 x 2 mm and set in the apparatus. Other measurement conditions are as follows.

Fluorine atom abundance F/(F4Fe40+C)X100 (atomic%) on carrier surface
Existence of each atom (peak area); (intake time/5tep) + (correction factor) (Example) The present invention will now be described in more detail with reference to Examples. However, the present invention is not limited to these examples in any way.

Harm, vaginal voice j-, -j- Magnetite (manufactured by To11 Kogyo, 1shi PTIOQO) 7
0 parts by weight Styrene-acrylic 1F combination (85/+5)
27-polyvinylidene fluoride (KYNAR, Penn Wal1, USA) 91 [a
The two components were melt-kneaded using a pressure kneader, pulverized and classified using a turbo mill and a classifier to obtain a carrier having an average particle size of 60 μm.

When the atomic composition of the surface of this carrier was analyzed by the ESCA method, the amount of fluorine atoms present was 20 atomic%.

The manufacturing conditions for the carrier of U-shaped Example 1 were different in that a twin-screw extrusion kneader was used instead of the pressure kneader, and the other conditions were exactly the same, but -F carrier with an average particle diameter of 60 μm was prepared. was manufactured.

The abundance of fluorine atoms on the surface of this carrier is 12ato
mic%.

Warigokuretsu 1 Magnetite (manufactured by Toda Kogyo, EPTlooO) 70 weights t parts Styrene-acrylic copolymer (85/1.5)
24 parts by weight of polyvinylidene fluoride (KYNAR manufactured by Penn Wait, USA) 6 parts The above ingredients were melt-kneaded in a pressure kneader, pulverized and classified using a turbo mill and a classifier to form a carrier with an average particle size of 60μ. I got it.

The presence of fluorine atoms jJ on the surface of this carrier is 10at
omic%.

Dansao-1 - The manufacturing conditions of the carrier in Example 3 were different in that a twin-screw extruder was used instead of the pressurized knead, and the other conditions were exactly the same, but a carrier with an average particle size of 60 μm was used. Manufactured carrier.

The amount of fluorine atoms present on the surface of this carrier was 5 atomic percent.

Discount 1~4- Magnetite (manufactured by Toda Konigyo, EPTlooO) 70
Parts by weight Styrene-acrylic copolymer (85/15) 2
7 parts by weight Polyvinylidene fluoride (KYNAR, manufactured by Penn fal 1, USA) 3 parts by weight The above components were melt-kneaded in a pressurized Ni-Goo, pulverized and classified using a turbo mill and a classifier to obtain a carrier having an average particle size of 60 ul.

The amount of fluorine atoms present on the surface of this carrier is 6 atoms
ic%.

Comparative Example 2 A carrier with an average particle size of 60 ura was produced in the same manner as in Example 4 except that a twin-screw extrusion kneader was used instead of the pressurized kneader. did.

The amount of fluorine atoms present on the surface of this carrier is 2 atoms
ic%.

Comparative Example 3 Magnetite (manufactured by Toda Kogyo, EPT100O) 70 parts by weight Styrene-acrylic copolymer (85/+5) 30
"Heavy section" - Melt and knead the ingredients in a pressurized Negu, then crush and classify using a turbo mill and classifier to obtain an average particle size of 60.
A μ- carrier was obtained.

The amount of fluorine atoms present on the surface of this Kina 4 Riya is 05to
mic%.

The carriers obtained in the copy test examples and comparative examples were evaluated as developers. The toner used was FX-7770, which had an average particle size of 11 μl and was made of styrene-acrylic resin and carbon black.
A toner for copying machines (manufactured by Fuji Xerox Co., Ltd.) was mixed with a carrier at a concentration of 3% by weight to prepare a developer. For these developers, the photoreceptor speed was 350 m5/s.
EC and developing magnetic roll (sleeve) speed 550m++
/sea was subjected to a life test using an evaluation bench machine, and the results shown in the following table were obtained.

(Effects of the Invention) By employing the above configuration, the present invention was able to impart a high charge amount to the toner and ensure a long life of the developer and high-speed development.

Claims (1)

[Claims] In a dry developer carrier containing a binder resin and magnetic powder, the binder resin contains fluororesin powder, and
The abundance of fluorine atoms among all atoms on the carrier surface is 6 to 3.
A carrier for a dry type developer characterized by having 0 atomic%.