JPS59223459A - Carrier particle for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To enable electrostatic charging of a toner to positive and to decrease the change in the electric resistance of a core material by treating the surface of the core material with an org. silane compd. to form a coating layer of the org. silane compd. on the surface. CONSTITUTION:Carrier particles for developing an electrostatic charge image contains core particles and a coating layer of an org. silane compd. at least the terminal of which is perfluorinated. The org. silane compd. can be expressed by the general formula, in which A denotes an alkylene group, fluoroalkylene group, halogen subst. fluoroalkylene group, arylene group, fluoroarylene group or halogen subst. arylene group, B denotes an alkylene group, oxyalkylene group or polyoxyalkylene group, R denotes an alkyl group of 1-4 carbon atom and n denotes 1-3 positive integer. There are magnetic particles such as triiron tetroxide, gamma-iron sesquoxide, cobalt, etc. and particles, etc. dispersed with these magnetic particles in the binder resin as the core material. The amt. of the org. silane compd. to be used for coating is about 0.001-0.5pts.wt. by 100pts.wt. the core material.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to electrostatic image development carrier particles used for the development of electrostatic latent images. More specifically, the present invention relates to carrier particles for developing electrostatic images having high durability and comprising core particles and a coating layer.

In the conventional electrophotographic method, a photoconductive substance such as selenium is used as a photoreceptor, a spot-like latent image is formed on it by various means, and a magnetic brush development method or the like is applied to this latent image. Generally, a method is adopted in which toner is attached and visualized using a method.

In this development step, carrier particles called carriers are used to impart an appropriate amount of positive or negative charge to the toner. Carriers can be broadly classified into coated carriers and non-coated carriers, but coated carriers are superior in terms of developer life, etc., and various types of coated carriers have actually been manufactured and put into practical use. There is.

This coated carrier is required to have various properties, among which the most important properties are appropriate chargeability,
Examples include impact resistance, abrasion resistance, and good adhesion between the core (core material) and the coating material.

Considering the above-mentioned required characteristics, the coat carriers used in the past still have problems to be improved, and no perfect one is known at present. For example, fluorinated vinyl polymers have excellent chargeability, but they have problems with adhesion to the core, and acrylic polymers are satisfactory in terms of mechanical strength and adhesion to the core, but have good chargeability. It is said that there is a problem with this. In any case, currently we are forced to use coating materials that have advantages and disadvantages. Particularly, when an organic photoreceptor is used as a photoreceptor, it is necessary to positively charge the toner, and this charging control has been carried out by selecting the carrier's σ material in a continuous manner.

Fluorinated vinyl polymers have been frequently used in conventional amounts for such purposes. However, as mentioned above, fluorinated vinyl polymers have poor adhesion to the core and also have problems in impact resistance. Furthermore, carriers with this type of coating have the disadvantages of high insulation, pronounced edge effects, and extremely low solids concentration.

Purpose of the Invention Under these circumstances, the inventors of the present invention have conducted various studies and examinations in order to improve the drawbacks of the above-mentioned conventional methods.As a result, the present inventors have developed an electrostatic image development method that exhibits predetermined characteristics by surface treatment with a specific silane compound. We have found that it is possible to obtain carrier particles for

That is, an object of the present invention is to provide a coated carrier that has excellent negative chargeability and less change in the electrical resistance of the core.

The above and other objects of the present invention will become more apparent from the following description.

DESCRIPTION OF THE INVENTION The above-mentioned objects of the present invention can be achieved by carrier particles for electrostatic image development comprising a core particle and a coating layer of at least a terminal cover fluorinated organosilane compound.

The organic compound used in the present invention can be represented by the following general formula.

(CF5-A-BSeSt-6OR)A-nHowever, in the general formula, A is an alkylene group, a fluoroalkylene group, a halogen-substituted fluorotetrafluorolene group, an arylene group, a 70roarylene group, or a halodane group. It represents a substituted arylene group, B is an alkylene group, oxyalkylene group or polyoxyalkylene group, R represents an alkyl group having 1 to 6 carbon atoms, and n represents a positive integer of 1 to 3 carbon atoms.

Preferably, the alkylene has carbon atoms/g, and the polyoxyalkylene contains - to g oxyalkylene.

Specific examples of the above-mentioned organic silane compounds perfluorinated at least at the terminal are 'f-7 and -7o.

Propylpropyltrimethoxysilane, 7-z4-
70 butylzolopyltrimethoxysilane, r-no-fluoroglobil f-ropyltriethoxysilane, γ-
Par70 butylpropyltriethoxysilane, γ
- Par70 lohexyl, proyl trimethoxycin,
γ-/4'-71:I l:l Octylg is pyrutrimethoxysilane, γ-par70Rohe'F Shea
/ 7'robiltriethoxysilane, γ-noyaichi 7
0-octylprobyltriethoxysilane, δ-/p-
7oaf lovir butyltrimethoxysilane, δ-per70 lozotylbutyltrimethoxysilane, δ-perfluoropropylbutyltriethoxy7rane, δ-per70 butylzotyltriethoxysilane, bis-
(γ-/'?-7oo7'rovirpropy/I/)dimethoxysilane, bis-(γ-)gu-70lozoti/L/
f-rovir) dimethoxysilane, bis-(r-79-
fluorob, robil globil) jetoxysilane, bis-(gamma-perflo of thirp pyl) jetoxysilane, r-per 70 poxyprobyl trimethoxysilane, r-perfluoro-70 poxypropyl trimethoxysilane, r-747 tetrachlorogropoxypropyltriethoxysilane, γ-propyrologoxypropyltriethoxysilane, γ-per70lohexyloxyderobyl trimethoxysilane, γ-propyrofluorooctyloxyzolopyltrimethoxysilane Silane, δ-Noguichi 70rozo-butyltrimethoxysilane, δ
-Par70 buttoxybutyltrimethoxysilane, δ
-Per70 lohexyloxybutyltrimethoxysilane, δ-per70 looctyloxybutyltrimethoxysilane, bis-(γ-per70 lobutoxyprobyl)
Dimethoxysilane, bis-(δ-perfluorohexyloxybutyl)jethoxysilane, etc. can be used. These can be used alone or in combination of one or more.

On the other hand, the core materials used in the present invention include triiron tetroxide,
r-iron sesquioxide, MnZn ferrite, NiZn
Ferrite, Ha ferrite, chromium dioxide,
Examples include magnetic particles of iron, nickel, cobalt, etc., and particles in which these magnetic particles are dispersed in a binder resin.

A size of about μm is used.

The carrier particles for developing electrostatic images of the present invention can be obtained by surface-treating the core material as described above with the organic silane compound described above, and forming a coating layer of the organic silane compound on the surface of the core material by chemical bonding or adsorption. You can get good results.

For surface treatment of the core material, for example, the silane compound is dissolved in an appropriate solvent, the core material is immersed in the resulting solution, and then the solvent is removed, dried, and baked at high temperature. A method can be used in which the material is suspended in a fluidized bed, a solution containing a silane compound is sprayed, dried, and baked at a high temperature. In these methods, high-temperature baking is not necessarily required, but from the viewpoint of increasing the adhesion strength between the core material and the silane compound coating, it is preferable to perform high-temperature baking at about 70 θ to 200 cc.

As the solvent for the organic silane compound, known solvents such as 11° alcohols, ketones, and toluene can be used.

The amount of the organic silane compound coated is usually approximately 3 parts by weight, O0θθ/~θ, per 100 parts of the core material. For this purpose, it is desirable that the concentration of the silane compound solution used in the surface treatment of the core material is approximately O0S~/θwt.

The carrier of the invention thus obtained is mixed with a toner and used for developing an electrostatic latent image. Examples of the toner include fine particles in which a colorant is dispersed in a binder resin, which are commonly used in electrophotography.

Invention Da 11-! 47: When the carrier of the present invention is mixed with a commonly used electrophotographic toner, the carrier is capable of positively charging the toner, yet provides an appropriate amount of charge and a significantly faster charging rate. be able to. Furthermore, the change in electrical resistance of the core material due to coating treatment is small, making it possible to obtain a low-resistance coated carrier and providing a developer with excellent solid reproducibility. In addition, since the coating suppresses toner contamination, the carrier has a long lifespan.
In addition, the carrier of the present invention has many advantages, such as being able to obtain a developer with a long shelf life, and being able to be manufactured by a simple process such as immersion in a solution, spray application of a solution, or, if necessary, heat treatment. are doing.

EXAMPLES The present invention will be explained in more detail with reference to Examples. All "parts" in the examples represent parts by weight. However, the present invention is not limited to these Examples in any way.

Example-7 S of r-par70proptylglobiltrimethoxysilane
Pour 100 parts of % acetone solution into a stainless steel beaker, add 200 parts of iron oxide powder with an average particle size lθ0 μm,
It was left for 7 hours. After removing most of the solution by decantation, the sample in the stainless steel beaker was transferred to a vacuum dryer together with the beaker, and dried at room temperature under reduced pressure with an aspirator. Next, the temperature of the dryer was raised to 10Occ, and the product was dried under reduced pressure for 1 hour. After cooling, it was taken out from the dryer to obtain carrier particles for electrostatic charge development treated with a silane compound according to the present invention.

A developer was prepared by mixing 100 parts of this carrier particles and 3 parts of an electrophotographic toner containing styrene-n-dityl methacrylate copolymer as a binder resin, and the amount of charge was measured. Positive charge (+7.2.5μc7
g), and when a development test was carried out using a copying machine using an amorphous silicon photoreceptor as a photoreceptor, a clear image was obtained.

Example - Spherical iron powder with an average particle diameter of θθ was washed with isozo H-byl alcohol and further washed with water.

The washed iron powder was immersed for 30 seconds in an aqueous sodium hydroxide solution whose pH was adjusted to 1/2, and the water was drained and thoroughly washed. After further washing this iron powder with acetone, 60q
It was dried for 1 hour at normal pressure and cooled. 1 part of γ-par 70-octylglobyltrimethoxysilane was dissolved in 70 parts of methyl ethyl ketone, and 100 m of the above-mentioned washed iron powder was added. - After being left to stand overnight, the thin liquid was removed by decantation, and drying was performed in the same manner as in Example-7. After cooling, coarse particles were sieved to obtain electrostatic charge developing carrier particles treated with a silane compound according to the present invention.

A developer was prepared in the same manner as in Example-/, and the charge amount was 6.
, OμC/I, and when a development test was carried out in the same manner as in Example-/, a clear image was obtained.

Claims (1)

[Claims] 1. A carrier particle for developing an electrostatic image, comprising a core particle and a coating layer of an organic silane compound having at least two terminal groups.