JPS6252561A - Toner for electrophotography - Google Patents

Abstract

PURPOSE:To provide a titled toner having an extremely strong positive electric charge control effect and excellent retentivity and stability of the positive charge control effect by incorporating fine particles formed by treating vapor phase method silica having >=50m<2>/g specific surface area with an epoxy group-contg. silane then amine into said toner. CONSTITUTION:This toner contains the fine particles formed by treating the vapor phase method silica having >=50m<2>/g specific surface area with the epoxy group-contg. silane then amine. The epoxy group-contg. silane to be used has the epoxy group having easy reactivity with the silanol group on the silica surface and having large reactivity with the amine. The amine is chemically bound to the silica surface by the easy reactivity of the epoxy group with the amino group and a high concn. of the amino group can be fixed to the silica surface if an epoxy silane is brought into reaction with the vapor phase method silica and is thereafter the amine is acted thereto. The grain size of the silica particles is preferably in a <=0.05mum range in particular.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electrophotographic toner, and more specifically, it is capable of imparting strong positive charging characteristics without adversely affecting the hue of the toner. Regarding toner. The present invention also relates to a color toner, particularly a translucent color toner that can be subjected to overlapping development processing and can be advantageously used for producing color copies, trumpet arrangements for overhead projects, and the like.

(Technical Ill of the Prior Art and Invention! The toner used for developing an electrostatic latent image in the electrophotographic method has a band 1t% property controlled to have a polarity opposite to that of the electrostatic image. For example, in developing a negatively charged image, it is important that the toner particles have positive charging characteristics.
For this purpose, it is necessary to incorporate a positive charge control agent into the toner particles. Most of the conventionally used positive charge control agents are dye-based, for example, oil-soluble dye-based, and these inevitably color the toner itself in a unique hue.

Particularly in the case of single-color toners, the mixing of charge-control dyes with the regular colorant adversely affects the tone of the color toner. In the case of toner, this results in a loss of color sharpness.

Positive charge control agents that do not exhibit a unique hue are already known; for example, Japanese Patent Publication No. 53-22447 proposes the use of aminosilane-treated metal oxide powder as a positive charge control agent for toner. .

(Summary of the Invention and Objectives of the Invention) The present inventors have discovered that fine particles obtained by treating vapor-phase silica with a specific surface area of 50 m2711 or more with an epoxy group-containing silane and then with an amine, when incorporated into toner particles. It has been found that it exhibits an extremely strong positive charge control effect and is also excellent in sustainability and stability of the positive charge control effect.

That is, an object of the present invention is to provide an electrophotographic toner containing a control agent that has an extremely strong positive charge control effect and is excellent in sustainability and stability of the positive charge control effect.

Another object of the present invention is to provide an electrophotographic toner containing a control agent having the above-mentioned effect without coloring the toner particles in a specific color tone.

Still another object of the present invention is to provide a color toner that has excellent light transmittance and is capable of superimposed development processing.

(Structure of the Invention) According to the present invention, there is provided an electrophotographic toner containing fine particles obtained by treating vapor-phase silica having a specific surface area of 50 m27i or more with an epoxy group-containing silane and then with an amine. is provided.

The present invention is particularly effective when amines having a plurality of amino groups in the molecule, particularly high molecular weight amines, are used as the amines.

(Characteristics and Effects of the Invention) The present invention provides two methods in which vapor-phase silica is first reacted with an epoxy group-containing silane and then reacted with amines.
The knowledge that by adopting the step reaction means, this reaction product exhibits an extremely strong positive charge control effect when incorporated into toner particles, and also has excellent sustainability and stability of the positive charge control effect. It is based on

Vapor-phase silica is generally known as Aerosil, and has one of the smallest particle sizes among various inorganic fillers, and has excellent dispersibility in resin binders.
Moreover, it has the property of not impairing transparency itself. Vapor-phase silica, like ordinary amorphous silica, itself has a negative chargeability, while organic compounds containing basic nitrogen atoms generally have a positive chargeability. are doing. In the present invention, from this viewpoint, the fine amorphous silica particles described above are surface-treated with an organic compound containing a basic nitrogen atom and not having a chromophore itself, that is, amines. It is important for the purpose of the present invention to react the gas-phase silica with the epoxy group-containing silane and then to react it with the amines.

First, the epoxy group-containing silazies used in the present invention are easily reactive with silanol groups on the silica surface, and
It is characterized by having an epoxy group that is highly reactive with amines. (If epoxysilane is reacted with vapor-phase silica and then amines are applied to the silica, amines can be applied to the silica surface due to the easy reactivity between epoxy groups and amino groups.) Through chemical bonding, a high concentration of amino groups can be fixed on the silica surface.

Vapor-phase silica has a significantly lower concentration of surface silanol groups than normal amorphous silica, such as wet-process silica, so when aminosilanes are directly applied,
The rate at which aminosilanes are chemically fixed is relatively small, and this is thought to be the reason why it is difficult to obtain a sufficiently large positive charge control effect, and the persistence and stability are insufficient.

On the other hand, according to the present invention, even when the surface cranol formation of vapor-phase silica is small and therefore the amount of silanes fixed is relatively small, the reactivity between the epoxy group and the ξ) group can be improved. This makes it possible to increase the concentration of amino groups chemically bonded to the silica surface. This effect is more remarkable when amines having a plurality of amino groups in the molecule, particularly high molecular weight amines, are used as the amines.

In addition, when the positive charge control agent of the present invention is used, it does not become colored (and has excellent transparency, so it can be advantageously used for translucent color applications.Furthermore,
Another advantage is that the cost of the charge control agent can be reduced by reducing the amount of expensive silanes used.

(Preferred Embodiment of the Invention) In the present invention, the vapor-phase silica used has a specific surface area of 50 m27 or more, particularly 150 m27 or more. This vapor phase silica may be silica alone, or may contain some At, 0. or TiO2. The particle size of the silica particles is preferably in the range of 0.2 μm or less, particularly 0.05 μm or less.

As the epoxy group-containing silane, trialkoxysilanes having an epoxy group such as glycidyl group and epoxycyclohexyl group are used, and suitable examples thereof are as follows.

r-glycidoxypropyltrimethoxysilane, β-(
3,4-Epoxycyclohexyl)ethyltrimethoxysilane.

Examples of amines include diethylenetriamine, triethylenetetramine, dimethylaminopropylamine, dimethylaminomethylphenol, tri(dimethylaminomethyl)phenol, ethylenediamine, tetramethylenecyamine, diethylua, minopropylamine, benzyldimethylamine, and Examples include dilene diamine, xylylene diamine, polyvinylamine, polyvinylpyridine, polyvinylimidazole, polyethyleneimine, polyethylene polyamine, polyamide polyamine, etc. Among these, those having multiple amino groups in the molecule, Polymeric polyamines are advantageous for the purposes of this invention.

Surface treatment of vapor phase silica with epoxy group-containing silane is carried out by bringing the silanes or their solutions into sufficient contact with the silica, and this treatment can be easily carried out by, for example, a stirring pouring method, a stirring spray method, etc. It will be held on. This epoxysilane-treated silica is treated with the above-mentioned amines or a solution thereof to cause a reaction between the amines and the epoxy groups.

Although the reaction proceeds satisfactorily at room temperature, the reaction can be accelerated if necessary by heating. The reaction treatments may be performed sequentially in the same container or in different containers.

The amount of epoxy group-containing silane added to vapor-grown silica can vary over a wide range, but is generally 0.01 per silica.
A suitable range is from 10 to 10% by weight, and on the other hand, the amount of amines added is preferably from 0.005 to 5% by weight, particularly from 0.05 to 0.5% by weight. . Unreacted components can be removed by washing, extraction, or other means.

The above-mentioned charge control agent may be used in an amount of 0.1 to 20% per fixing resin.
It is also important to use the amount in an amount of 0.2 to 15% by weight. If the amount is less than the above range, the desired charge control effect cannot be obtained, whereas if the amount is more than the above range, transparent Light properties tend to be impaired.

In the present invention, as a coloring agent, a particle size of 0.2 μm or less,
In particular, it is desirable to use organic pigments or dyes with a diameter of 0.05 μm or less, which can impart translucency to the final toner image and enable overlapping development processing. Many inorganic pigments have particle sizes considerably larger than the above particle size range and are not suitable for the purpose of the present invention. Furthermore, if the particle size of the organic pigment is larger than the above-mentioned particle size, the light transmittance will be significantly impaired.

The type of organic pigment is not particularly limited as long as it has the above-mentioned particle size, but examples include blue-green phthalocyanino pigments, yellow-red azo pigments, metal complex salt raw materials, triphenylmethane pigments, and vat dyes. Edge pigments etc. are used. The organic pigment having the above particle size can be obtained by crystallizing the pigment into fine crystals at the final stage of pigment production. Furthermore, as the dye, an oil-soluble dye used for coloring plastics is used.

These organic pigments or dyes are preferably used in an amount of 1 to 20% by weight, especially 2 to 15% by weight, based on the fixing resin medium.

As the fixing resin medium, resins used in the production of this type of toner are used, and particularly preferred are various mono- or diethylenically unsaturated monomers, especially (α) vinyl aromatic monomers. (b) Homopolymers and copolymers of acrylic monomers are used.

Examples of the monomer (α) above include styrene, vinyltoluene, α-methylstyrene, α-chlorostyrene, vinylxylene, vinylnaphthalene, etc.
In addition, as the monomer (b), acrylic acid, methacrylic acid, ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate), 2-ethylhexylmethac I) V
-), 5-hydroxyglobyl acrylate, 2-hydroxyethyl methacrylate, 6-amituprobyl acrylate, 5-N,N-diethylaminopropyl acrylate, acrylamide, and the like.

These monomers (other monomers used in combination with (1) or (A) or alone include butadiene,
Isoprene, chloroprene, etc. may contain other ethylenically unsaturated carboxylic acids or their esters such as maleic anhydride, fumaric acid, crotonic acid, and itaconic acid, vinyl esters such as vinyl acetate, vinylpyridine, vinylpyrrolidone, and vinyl ether. , acrylonitrile, vinyl chloride, vinylidene chloride, and the like.

The molecular weight of these resins is 5,000 to 600°00
It is desirable that the VC is in the range of 0, VC5,000 to 2[10,00[].

The above-mentioned colorant and charge control agent are blended into this fixing resin medium along with other blending aids if necessary, and this is uniformly mixed.
The toner is uniformly kneaded and then granulated to form a toner. For example, in a method in which the developer is fixed with a hot roll, an anti-offset agent such as silicone oil, low molecular weight olefin resins, various waxes, etc. may be added to the total amount of 2.
It can be used in amounts ranging from 15% to 15% by weight. In addition, for applications in which the developer is fixed with a pressure roll, a pressure fixing agent such as paraffin wax, various animal/vegetable waxes, fatty acid amide, etc. may be used in an amount of 5 to 60 parts by weight per whole. .

For molding, the above-mentioned cross-wire composition is cooled, then pulverized and, if necessary, sieved. Of course, there is no particular problem in performing rapid mechanical stirring in order to round off irregularly shaped particles. Although the particle size of the toner particles is related to resolution and other factors, it is generally desirable that the particle size is within the range of 5 to 65 microns.

The toner according to the present invention can be used as a two-component developer for color development in combination with a magnetic carrier such as triiron tetroxide, 7-elite, iron powder, etc. Useful for making copies.

The invention is illustrated by the following example.

(Example) Production of charge control agent used in the toner of the present invention Methanol 2
A treatment solution was prepared by dissolving 1 g of γ-glycidoxyglobyltrimethoxysilane in a mixed solvent consisting of 0.00ml and 20ml of water. 20 g of silica (Aeroge #200; primary particle average diameter 0.012 μm) was dispersed in this and refluxed for about 10 hours. After the reaction, it was washed twice with methanol and dried in a vacuum desiccator for 24 hours. Subsequently, the mixture was reacted with 0.5 g of 1,6-bropanediamine in 200+1/20% tetrahydrofuran containing a catalytic amount of acetic acid (reflux). After the reaction, wash twice with tetrahydrofuran and wash once in a vacuum desiccator.
It was dried for 2 hours. Finally, it was pulverized to obtain a charge control agent.

Charging characteristics of the toner of the present invention The above-mentioned materials were uniformly stirred and mixed in a mixer. This mixture was kneaded at 150° C. using two rolls, then coarsely ground using a cutting mill, and then finely ground using a jet mill. Finally, it is classified to 5 to 25 μm (average particle size 15 μ7).
7ri toner.

This toner was transferred to an iron powder carrier (Japan Iron Powder 5TV-25).
7) at a ratio of 1:20 (weight ratio) and stirred to prepare a developer. This toner band of the present invention is ¥! When Li' was measured using the blow-off method, it was confirmed that it was strongly charged ((18 μC/11)).
OHP set on C-161 modified machine (manufactured by Sanda Kogyo Co., Ltd.)
When copying was done using a sample manuscript on film,
A clear image was obtained.

At the same time, this copy had excellent translucency, and when used as an original for a projector, a bright yellow image was projected on the screen.

Patent applicant: Sanda Kogyo Co., Ltd. -“X

Claims (3)

[Claims] (1) An electrophotographic toner characterized by containing fine particles obtained by treating vapor phase silica having a specific surface area of 50 m^2/g or more with an epoxy group-containing silane and then with an amine. (2) The toner according to claim 1, wherein the amine is an amine having a plurality of amino groups. (3) The toner according to claim 1, wherein the amine is a high molecular weight amine.