JPS63191154A - Electrostatic charge image developer - Google Patents

Abstract

PURPOSE:To maintain good cleanability of a photosensitive body and to prevent deterioration in the characteristics such as electric chargeability of a toner by internally adding a lubricant selected from metal soap, fatty acid, fatty acid ester, and fluorine compd. into toner particles and bleeding the lubricant onto the surface of the toner particles, thereby constituting the toner. CONSTITUTION:This toner is formed by internally adding the lubricant selected from the metal soap, fatty acid, fatty acid ester, and fluorine compd. into the toner particles and bleeding the lubricant on the surface of the toner particle. All the toner particles have lubricity, if the lubricity is provided to the toner particles themselves by internally adding the lubricant to the toner particles and bleeding the lubricant on the surface of the toner particles. The lubricant is thereby stuck to the surface of the photosensitive body while the good cleanability is maintained, by which the deterioration in the characteristics of the photosensitive body is prevented. Since the electric charge is the charge between the toner and carrier. The charge characteristic is stabilized unlike in the case of external addition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to electrostatic image developers, and particularly to such toners that have excellent cleaning properties without impairing other properties.

[Prior art and problems to be solved by the invention] As a method for cleaning residual toner on a photoreceptor drum in an electrophotographic copying machine or printer, a blade method,
Various cleaning methods are used for this cleaning, such as the brush method and the web method, but as the copying or printing process continues tens of thousands of times, toner that cannot be removed by these cleaning methods gradually accumulates on the surface of the photoreceptor. This causes inconveniences such as so-called poor cleaning or toner filming.

In order to deal with this phenomenon and improve the cleaning performance of residual toner on the photoreceptor drum, it is known that it is effective to supply zinc stearate, which is a metal soap, to the surface of the photoreceptor. However, fine particles such as zinc stearate film on the photoreceptor, and when the photoreceptor is made of amorphous selenium, they promote crystallization of selenium, deteriorating the characteristics of the photoreceptor, and as a result, reducing image quality. be.

Therefore, in order to eliminate such adverse effects, for example, Japanese Patent Application Laid-Open No. 59-228667 proposes adding copper stearate together with zinc stearate to prevent crystallization of selenium. However, even with this, the promotion of selenium crystallization is not completely prevented, and charging occurs between the carrier, toner, and lubricant, and in particular, zinc stearate has the same positive chargeability as the toner. There is also a problem in that the charging of the toner becomes very unstable and the image is distorted.

[Means and effects for solving the problems] The present invention maintains good cleaning of the photoreceptor drum, does not promote crystallization of amorphous selenium, and does not deteriorate characteristics such as toner charging. The purpose of this method is to add a lubricant selected from metal soaps, fatty acids, fatty acid esters, and fluorine compounds to the toner particles, and apply the lubricant to the surface of the toner particles. An electrostatic image developer characterized by being formed by exudation.

In the present invention, a lubricant is added internally to the toner particles and exudes onto the surface of the toner particles, thereby imparting lubricity to the toner particles themselves. As a result, all toner particles have uniform lubricity, resulting in good cleaning properties. However, unlike when a lubricant is added externally, it is prevented from adhering to the surface of the photoreceptor and degrading the characteristics of the photoreceptor, and the charging characteristics are also charged between the toner and the carrier. Unlike the case of external addition, it is stable.

Suitable lubricants for use in the toners of the present invention include metal soaps, fatty acids, fatty acid esters, and fluorine compounds. Metal soaps include aluminum stearate, calcium stearate, calcium laurate,
Zinc stearate, zinc claurate, zinc myristate, magnesium stearate, fatty acids include caproic acid, stearic acid, capric acid, lauric acid, myristic acid, valmitic acid, arginic acid, behenic acid,
Saturated fatty acids such as lignoceric acid, myristoleic acid,
Unsaturated fatty acids such as palmitoleic acid, oleic acid, linoleic acid, and lylunic acid; fatty acid esters include butyl stearate, butyl laurate, isopropyl myristate, isopropyl palmitate, octyl palmitate, stearyl stearate, methyl laurate, and myristic acid. methyl acid, methyl oleate, and medium-chain fatty acid glycerides, and as fluorine compounds, aromatic fluorine compounds such as ortho-fluoronitrobenzene, aliphatic fluorine compounds such as trifluoroethyl acrylate,
Examples include fluorosurfactants such as fluoroalkyl (C2-C1o) carboxylic acids.

The lubricant that can be added to the toner of the present invention is essentially not particularly limited as long as it is a lubricating substance. For example, even if a substance such as zinc stearate has disadvantages such as degrading the characteristics of the photoreceptor (amorphous selenium) when added externally to toner and carrier, it can be added internally to toner particles to prevent external addition. Since the lubricant does not easily and in large quantities adhere to the surface of the photoreceptor as in the case of photoreceptors, the toner of the present invention can utilize the properties of the lubricant more advantageously. Further, the sign of the charge of the lubricant is not a problem as in the case of external addition, so either a positively chargeable lubricant or a negatively chargeable lubricant may be used. Incidentally, the charging property required for the toner may be covered by the charging property of this lubricant, and in this case there is an advantage that there is no need to add a charging agent.

The amount of lubricant added internally to the toner of the present invention is 1 to 10% by weight, preferably 2 to 5% by weight, based on the toner. If the amount of lubricant is too small, the cleaning performance will not be sufficient, while if the amount of lubricant is too large, the lubricity will be excessive and the fluidity of the developer will be too good, causing it to easily slip from the developing sleeve, resulting in poor development. be.

The lubricant added internally into the toner particles according to the present invention, after being added, is transferred to the surface of the toner particle by its own migration properties or under the action of additives added to promote this migration property. The toner oozes out to the surface of the toner, and exists uniformly or dispersedly in the form of a film or a lump on the surface of the toner. In this way, the lubricant exists in the form of a film on the surface of the toner particles, thereby providing the necessary cleaning properties. At this time, the film thickness of the lubricant is preferably about 0.001 to 0.5 μm. This film thickness can be changed depending on the amount of lubricant added.

The most suitable method for internally adding the lubricant into the toner is to prepare toner particles by a suspension polymerization method, and then add the lubricant to the suspension during the suspension polymerization.

According to this method, an appropriate amount of the lubricant can be uniformly dispersed in the toner particles, and the lubricant can also be exuded more uniformly. In this case, this uniformity is good for what dissolves in the monomer. In the suspension polymerization method, thermoplastic resin monomers and the like are usually suspended in water, and polymerization proceeds while the monomers take in the added components to produce a spherical toner. Therefore, when a lubricant is added to this suspension, the lubricant is also incorporated into the monomer droplets, and the lubricant is uniformly added internally into the toner particles formed by polymerization of the monomers. At this time, in order to incorporate the lubricant into the monomer oil droplets,
It is preferable that the lubricant has a melting point within the polymerization temperature range of 50 to 180° C., and is added to the suspension and melts into oil droplets, and a lubricant that is liquid at room temperature is not used. In addition, in order to efficiently add the lubricant inside the toner, the lubricant should be 0.01 to 5.
It is preferable to add it with a μ-0 particle size.

The toner of the present invention is the same as a conventional toner except that a lubricant is internally added, and the composition, shape, dimensions, manufacturing method, etc. of the toner may be the same as conventional toners. However, regarding the manufacturing method, as mentioned earlier, the suspension polymerization method is the most suitable because it allows the lubricant to be added internally more uniformly.
The suspension polymerization method can also follow a conventional method. Typical toners are made of thermoplastic resins such as styrene-methacrylate copolymers and polyester resins containing colorants such as carbon black and nigrosine dyes.Additional chargers, dispersants, and stabilizers are added as necessary. Contains agents etc.

〔Example〕

70 parts of Ogaban styrene, 30 parts of n-butyl methacrylate, 5 parts of carbon black, 2 parts of nigrosine dye, 5 parts of low molecular weight polypropylene, 2 parts of azobisisobutyronitrile,
In addition, zinc stearate (NOF) is added as a lubricant.
0.5 part of the product (average particle size: 4 μm) was added, suspended in water by a known method, and polymerized at 50° C. for 8 hours and at 130° C. for 2 hours to complete the reaction. Zinc stearate, which was uniformly dispersed in the monomer, did not dissolve in the polymer, so the lubricant oozed out onto the toner surface. Thus, the average particle size 1
A toner of 3 μm was obtained. This toner was classified into 5 to 20 μm (particles with particle diameters of less than 5 μm and more than 20 μm were excluded).

This toner was mixed with a carrier and evaluated using a copying machine (Toshiba RheoDry 4515) using amorphous selenium as a photoreceptor material. This copying machine forms a positively charged image on a photoreceptor,
This mechanism uses a magnetic brush method to develop the photoreceptor, and then uses a urethane rubber cleaning blade to clean the toner remaining on the photoreceptor.

Continuous copying of 50,000 sheets was carried out, and the cleaning performance was good, the amount of charge did not decrease, no deterioration of the characteristics of amorphous selenium was observed, and the image quality was as good as the initial one without any disturbance.

In the comparison example, a toner was obtained without internally adding zinc stearate, and zinc stearate (manufactured by NOF Corporation, average particle size 4 μl 11) was externally added to the toner classified into 5 to 20 μm using a Henschel mixer. The mixture was mixed to prepare a developer.

When evaluated using the Toshiba RheoDry 4515 machine in the same manner as in the example, the cleaning performance was good with continuous copying of so and ooo sheets. The present invention provides a toner for developing electrostatic images on a photoreceptor that maintains good cleaning properties of the photoreceptor, does not promote crystallization of amorphous selenium, and does not deteriorate toner properties such as charging. provided.

Claims (1)

[Claims] 1. An electrostatic image developer characterized in that a lubricant selected from metal soaps, fatty acids, fatty acid esters, and fluorine compounds is internally added to toner particles, and the lubricant is exuded onto the surface of the toner particles.