JPH0218568A - Toner for electrophotography - Google Patents

Abstract

PURPOSE:To eliminate the fogging of an image and to sharpen the image by incorporating a specific compd. as a charge control agent into the toner. CONSTITUTION:The compd. expressed by the formula is incorporated as the charge control agent into the title toner. In the formula, R denotes 1-12C alkyl group; X denotes anion. Octamethylene bis-triphenylphosphynium, etc., are usable as the compd. expressed by the formula. This compd. has excellent dispersibility to a resin component and thermal stability, is colorless and imparts a positive charge to the toner; therefore, the toner which forms the sharp image and allows continuous use is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toner for developing electrostatic latent images in electrophotography.

(Prior art) In electrophotography, a latent image is formed on a photoconductor made of a photoconductive substance, and this is developed with a powder developer to make it visible. A two-component developer consisting of a mixture of a toner with a fluidizing agent dispersed therein and a carrier of iron powder or ferrite powder, a natural or synthetic resin, a coloring agent, a charge control agent, etc. They can be broadly classified into fluidizers and one-component developers made of magnetic materials.

A two-component developer achieves development by attaching charged toner to an electrostatic latent image through friction with a carrier. Conventionally, a one-component developer uses this instead of a carrier. Toner is known that is charged by friction with a brush-like or plate-like friction member that has the same function as that of the toner. It has become known that toner is charged by mutual friction with the toner. The photoconductor layer can be positively or negatively charged so that exposure under the original produces a positive or negative electrostatic latent image. Depending on the polarity of this electrostatic latent image, the developing toner remains positive or negative.

In order to keep the toner charged, it has been proposed to utilize the triboelectricity of the resin, which is the main component of the toner, but this method has a small charge on the toner and a large solid surface resistance value, so The resulting image is prone to fogging and becomes unclear. Therefore, in order to impart desired triboelectric charging properties to the toner, it has been attempted to add charge-imparting dyes, pigments, and even charge control agents, and these techniques are now in practical use in this technical field.

(Problems to be Solved by the Invention) However, these dyes and pigments used as charge control agents have complex structures and lack stability, such as mechanical friction and impact, changes in temperature and humidity conditions, and electrical resistance. It is easily decomposed or altered by impact, light irradiation, etc., and the charge adjustment ability is easily lost. One essential flaw is that, being a colored material, it violates the requirement that toners with a specific hue require a charge control agent that can be considered colorless or substantially colorless. .

(Means for Solving the Problems) The present inventors have developed a toner material that has good dispersibility with the resin component, has thermal stability up to a temperature that allows sufficient melt-kneading, and is colorless. They discovered a compound that can be removed by imparting a positive charge to the toner and invented an excellent toner.

That is, the present invention provides an electrophotographic method comprising a compound represented by the general formula (1) (wherein R represents an alkyl group of 1 to 12 and X represents an anion) as a charge control agent. It is a toner for use.

The alkyl group of the compound represented by the general formula (1) is a linear or branched alkyl group having 1 to 12 carbon atoms, preferably an alkyl group having 3 to 10 carbon atoms. The anion may be any suitable ion, but preferable examples include CI, Br-1-1ci
o″4, B F; , CH3-@-8o: and the like.

Next, a method for synthesizing the compound represented by general formula (1) will be explained. Reacting triphenylphosphine and a dihalogenated alkane in a polar solvent such as acetonitrile (thus, the compound of general formula (1) is obtained. Compounds whose anions are other than halogen can be easily reacted by an ordinary anion exchange reaction. can get.

Incidentally, the amount of the compound represented by general formula (1) added to the toner component is generally 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the resin. Make it contain.

In addition to the compound of general formula (1), the toner of the present invention includes:
In consideration of adhesion, preservability, fluidity, crushability, etc., one or more of the known toner resins such as styrene resin, styrene-acrylic resin, styrene-butadiene resin, epoxy resin, polyester resin, paraffin wax, etc. A mixture of several types is used. As the coloring agent, many known dyes and pigments can be used, but those that are particularly excellent as toners for color copying include benzidine yellow, quinacridine, copper phthalocyanine purple, and copper phthalocyanine green. .

The toner of the present invention is usually mixed with a carrier to provide a two-component developer, but can of course also be used as a one-component developer.

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

Note that parts in the examples represent parts by weight.

Examples include octamethylene bromide pist +) 7 x Synthesis of nylphosphinium 1,8-dibromooctane 24.5g, triphenylphosphine 41.2g, and acetonitrile 50g
+nl was placed in a flask equipped with a reflux condenser and a stirrer, and reacted under reflux for 1 hour. After cooling, the precipitate is collected by filtration, washed with acetone, and dried to obtain the desired white powder 52.
I got g. The melting point and elemental analysis results of this product are shown below.

Melting point 255°C Elemental analysis value C,, H,, P2Br2 calculated value: C6
6.34% 85.82% Actual value: C66, t) 6%
85.79% Examples 2 to 4 In the same manner as in Example 1, the compounds shown in Table 1 were synthesized. Table 1 shows their melting points.

Table 1 Example 5 A blend of 100 parts of styrene resin, 6 parts of carbon blank, and 2 parts of the compound obtained in Example 1 is uniformly premixed in a ball mill to prepare a premix. Next, it is heated, melted and kneaded, cooled, coarsely ground in a vibrating mill, and further crushed.
It was pulverized using a mill to obtain a black toner. The particle size of this black toner was 8 to 15 microns.

A developer was prepared by mixing 95 parts of iron powder carrier with 5 parts of the obtained black F car. The initial blow-off charge amount of this developer was 16.5 μC/g.

When a toner image was formed using this developer on a zinc oxide drum by magnetic brush development, a clear image without fogging was obtained. With this toner, no deterioration in copy quality was observed even after continuous copying] and after 00 sheets.

Example 6 100 parts of styrene-acrylic copolymer resin, yellow dye (C
A mixture of 6 parts of Diverse Yellow 33) and 2 parts of the compound obtained in Example 2 was treated in the same manner as in Example 5 to obtain a yellow toner. The obtained yellow toner I) Example 5
The initial blow-off charge amount of the developer prepared by straining it in the same manner as above was 17.4 μC/g.

When copies were made using this developer in the same manner as in Example 5, clear yellow images without fog were obtained. With this toner, no deterioration in copy quality was observed even after 10,000 continuous copies were made.

Example 7 Styrene-n-butyl methacrylate-Y copolymer resin 10
A blend of 0 parts of red dye (C, I, Pigment Red 12), 8 parts of the compound obtained in Example 3 was treated in the same manner as in Example 5 to obtain a red toner. As in Example 5, a clear red image without fogging was obtained from the obtained red toner. With this toner, no deterioration in copy quality was observed even after continuous copying of 000 (') sheets.

Example 8 100 parts of polyester resin, blue dye (C, I.

A blend of 6 parts of Pigment Blue 15) and 2 parts of the compound obtained in Example 4 was treated in the same manner as in Example 5 to obtain a blue toner. The initial blow-off charge amount of the developer prepared from the obtained blue toner in the same manner as in Example 5 was 17.3 μC.
/g.

When copies were made using this developer in the same manner as in Example 5, clear blue images without fog were obtained. With this toner, no deterioration in copy quality was observed even after 10,000 continuous copies were made.

(Effects of the Invention) The charge control agent used in the present invention has excellent mechanical friction and impact stability, temperature and humidity stability, and is colorless, so it can be used for electrophotography with clear images and continuous use. Toner was obtained.

Patent applicant Nippon Carlit Co., Ltd.

Claims (1)

[Claims] The following general formula (I) ▲There are numerical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R represents an alkyl group having 1 to 12 carbon atoms, and
^■ represents an anion. ) A toner for electrophotography, characterized in that it contains a compound represented by the following formula as a charge control agent.