JPS6153649A - Developer for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a developer for electrophotography by which an electrification quantity can be controlled appropriately, also an electrifying speed is high, and a stable electrifying property can be maintained extending over a long period of time, by making the developer contain a toner containing a partial fluorinated magnetic powder, or a carrier particle. CONSTITUTION:A magnetic powder of magnetite, etc. is immersed into a water solution of NH4F, and thereafter, dried up and burned in nitrogen by an electric furnace. Or the magnetic powder is brought to HF gas treatment, etc. by a fluid bed, and a partial fluorinated magnetic powder of 1-100wt% F content, such as that which has fluorinated the surface of the magnetic powder, that which has fluorinated the surface and the inside of the magnetic powder, etc. is used as a carrier. Also, the magnetic powder fluorinated by 20-80% is used as a toner. A partial fluoride in which an average particle diameter of the magnetic powder is large is used as a carrier as it is. That which has a small average particle diameter is dispersed into a binder, melted and mixed, and thereafter, crushed and classified, and used as a carrier. Also, in case of using the magnetic powder as a toner, it is mixed with the binder, melted and kneaded, and thereafter, crushed and dispersed, and it is obtained. In this way, a developer which is excellent in its electrification characteristic, weather resistance, fluidity, etc., and also stable extending over a long period of time is obtained as an electrostatic latent image developer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a developer for developing electrostatic latent images.

[Prior art]

A method of obtaining f% of copies by electrophotography or electrostatic recording is known. In this method, an electrostatic latent image formed on a photoreceptor or an electrostatic recording medium is developed with a developer, and the toner image is transferred onto a transfer paper and then fixed to produce a copy.

As this developer, a developer consisting of two components, carrier and toner, is generally used. By pressing the developer with your finger in the developing device, frictional electrification is generated between the carrier and the toner, giving the toner a charge of opposite polarity to the electrostatic latent image and attaching it to the latent image E5' to develop it. . Further, developers using magnetic toner are also used.

Conventionally, in the carrier or magnetic toner of such a developer,
Magnetic powders such as iron oxide powder, magnetite, or ferrite are used, but they have the drawback of large changes in charging properties due to impaction. In addition, to control the charging properties of conventionally used magnetic powders, surface treatment with inorganic or organic polymers is performed, but the bonds are weak and it is difficult to maintain stable charging properties over a long period of time. It has the disadvantage of being difficult.

[Purpose of the invention]

The object of the present invention is to provide a developer with fewer such drawbacks, that is, a developer that can maintain stable chargeability over a long period of time, has a charge amount controlled to an appropriate value, and has a high charging speed. That's true.

[Structure of the invention]

The object of the present invention can be achieved by an image agent containing partially fluorinated magnetic powder.

The partially fluorinated magnetic powder used in the present invention includes (1) magnetic powder whose surface is fluorinated, (II) magnetic powder whose surface and interior are partially fluorinated, and (III) magnetic powder. Fluorinated powder inside (T
V) A material with fluoride attached to the surface, (V) a mixture of fluoride and magnetic powder, etc. are used. ! 11. The above form [or (2) is preferable.

There are no particular restrictions on the method of partial fluorination of magnetic powder; for example,
A method in which a compound that is easily decomposed by heat such as ammonium fluoride is attached to magnetic powder and then heat treated, a method in which a reaction is performed with hydrogen fluoride gas, a method in which a fluoride solution is treated with acid, etc. are used as appropriate. be able to.

The magnetic powder used for the partially fluorinated magnetic powder in the present invention is not limited to bamboo as long as it can be partially fluorinated.

For example, magnetophyte, ferrite, rFe2O:
Oxide-based magnetic powders such as +, metal-based magnetic powders such as metallic iron, etc. can be used as appropriate.

The fluorination rate of the partially fluorinated magnetic powder in the present invention is 0.
01wt% to 7Qwt% is suitable.

When the partially fluorinated magnetic powder of the present invention is used in a carrier, the appropriate content is 1 to 1QQwt%.The partially fluorinated magnetic powder itself may be used as a carrier, or the magnetic powder binder resin may be used as a carrier. , a charge control agent, a conductivity modifier, etc., may be used in combination with other substances. Further, when the partially fluorinated magnetic powder is used in a magnetic toner, the content is 20 to 20%.
80% is appropriate, and components other than the partially fluorinated magnetic powder in the magnetic toner include known components such as binder resin, non-fluorinated magnetic powder, charge control agent, conductivity control agent, colorant, External additives etc. are used.

The average particle size of the carrier according to the method of the present invention is 10 to 500μ
m, and may be a commonly used large particle carrier, or may be used as a small particle microcarrier.

The average particle size of the magnetic toner produced by the method of the present invention is 5 to 30 μm.
is used, preferably 10 to 20 μm.

The method for producing the carrier or magnetic toner of the present invention includes a method in which the partially fluorinated magnetic powder is used as it is as a carrier, a method in which the partially fluorinated magnetic powder is kneaded with a binder resin and then pulverized, a method in which the binder resin is dissolved in a solvent, and the partially fluorinated magnetic powder is mixed with a binder resin and then crushed. Any of the following methods can be used: spray-drying a suspension in which magnetic powder is dispersed, or dispersing partially fluorinated magnetic powder in a monomer when polymerizing the binder resin.

When the carrier or magnetic toner of the present invention is used together with a non-magnetic toner, the non-magnetic toner may be any toner that can be charged by mixing with the carrier or magnetic toner, and the chargeability of the carrier or magnetic toner may be positive or negative. Further, in the case of magnetic toner, only the magnetic toner may be used without the non-magnetic toner.

The developer of the present invention is characterized by containing partially fluorinated magnetic powder, and the reason why the object of the present invention is achieved by this is due to the charging characteristics of this partially fluorinated magnetic powder. This is believed to be because it has excellent electrical, physical, and chemical 41+ properties such as weather resistance, fluidity, and surface energy.

In the partially fluorinated magnetic powder of the present invention, fluorine atoms are chemically bonded as metal atoms of the magnetic powder, thereby achieving the object of the present invention. In this respect, the present invention is completely different from conventionally known methods of surface coating with fluorinated polymers and methods using mixtures with fluorinated polymers.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Magnetite (dso = 0.5 μm) 10 times the weight of ammonium fluoride was immersed in a 5% aqueous solution of ammonium fluoride, impregnated with the aqueous solution, and dried on a water bath.The moss was dried in an electric furnace. After firing in a nitrogen atmosphere at 550°C for 2 hours, it was cooled to air temperature.

Next, it was dispersed in a sample mill and d again. =0.5
It was set as μm.

Example 2 Magnetite) (dso=Q, 5 μm) in a fluidized bed
It was treated with HF gas at 00°C to fluorinate.

The HF gas used was lQwt% of magnetite.

Example 3 100 parts by weight of iron powder with an average particle size of 100 μm was added to 3we%HF
The mixture was added to water and heated at 100°C for 1 hour, followed by dry combustion.

Career i! ! ! Preparation Example 1 30 parts by weight of styrene and n-butyl methacrylate copolymer 7 parts by weight of the partially fluorinated magnetic material of Example 1 were mixed, and after melt mixing, finely crushed and classified, the average A magnetic carrier with a particle size of 24.9 μm was used.

Carrier Production Example 2 Styrene, 2-acrylic acid, ethylhexyl copolymer 30 parts by weight Partially fluorinated magnetic powder of Example 2 70 parts by weight Carbon black
3 parts by weight were mixed, melted and kneaded, and then finely pulverized and classified to obtain a carrier having an average particle size of 25.1 μm.

Carrier manufacturing example 3 The partially fluorinated magnetic powder of Example 3 is used as is.

Magnetic toner production example Styrene-n-butyl methacrylate copolymer (number average molecular weight approximately 9000) 20WL%, styrene-butadiene crosslinked polymer (gel fraction 90%) 2QwL%, low molecular weight ρ, p, wax (weight average molecular weight Emperor 4000
)5Wl;%, 83 minutes fluorinated magnetomagnetic 55W of Example 1
The magnetic toner with an average particle size of 14.9μ is produced by melting and kneading the powder, followed by pulverization and classification.

Carbon black (particle size 0.02
A toner with carbon black attached to the surface of the toner particles was prepared by adding 5 wt % of .mu.) and stirring with a stirring device having a stirring blade rotating at high speed in the stirring chamber.

Comparative Example 1 A carrier having an average particle size of 25.0 μm was prepared in the same manner as in Carrier Production Example 2, except that non-fluorinated magnetite was used instead of partially fluorinated magnetite.

Comparative Example 2 A carrier having an average particle diameter of 25.2 μm was prepared in the same manner as in Carrier Production Example 3 except that non-fluorinated magnetite was used instead of fluorinated magnetite.

Comparative Example 3 Iron powder having the same average particle diameter of 25.0 μm as in Carrier Production Example 1 was surface oxidized with air.

Toner production example-1 Styrene, n-butyl methacrylate copolymer (styrene: n-phthyl methacrylate 65:35, Mw = 75.000, Mn = 24
,000) 92 parts by weight carbon black (R
eagal 330: manufactured by Cabot)
6 parts by weight of graded ammonium salt (cetylpyridium chloride) 2 parts by weight (81 parts) were mixed, melted, kneaded, and pulverized to form a toner with an average particle size of 12.1 microns.

Toner production example-2

Claims (1)

[Claims] An electrophotographic developer characterized by containing partially fluorinated magnetic powder.