JPS6294853A - Developer for electrostatic latent image - Google Patents

Abstract

PURPOSE:To prevent the occurrence of unevenness of an image in an atmosphere at high temp. and humidity by incorporating a specified compound into a binding resin for an electrostatic developer so as to prevent the sticking of the toner even when continuous copying is carried out many times. CONSTITUTION:A binding resin for a toner is mixed with a compound represented by formula I (where each of X, Y and Z is hydroxyl, nitro, acetyl, butyl or acetylbutyl) or by formula II (where each of R1, R2 and R3 is H, methyl, ethyl, benzyl, trityl, cyanoethyl or carboxymethyl). The amount of the compound in the binding resin is 2-30wt%, preferably 10-20wt%. The toner may contain a colorant such as a pigment or dye as required. In case where the toner contains a magnetic material, magnetite is most preferably used as the magnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to a dry toner suitable for developing electrostatic latent images or magnetic latent images.

Conventional technology Conventionally, dry development methods used in electrophotography, electrostatic recording, etc.
There are two methods: a two-component developer and a one-component developer.

Although the method using a two-component developer produces relatively stable and good images, it has drawbacks such as deterioration of the carrier and fluctuations in the mixing ratio of toner and carrier.

In order to avoid the above-mentioned drawbacks of two-component developers, attention has been paid to developing methods using -component developers, especially those using high-resistance toner. - In a developing method using high-resistance toner, a thin layer of toner is formed on the circumferential surface of the developing sleeve that conveys the developer, and the necessary charge is sufficiently applied to the toner on the circumferential surface of the developing sleeve through friction. In order to do this, a suppressing member whose tip end is pressed against the developing sleeve is provided. The suppressing member has its tip pressed against the surface of the developing sleeve by the magnetic force of an internally installed magnet, thereby regulating the layer thickness of the toner on the peripheral surface of the developing sleeve, thereby forming a thin toner layer.

Furthermore, in an electrophotographic copying machine, the development characteristics required of the developing device are different depending on whether the original is a line image or a solid image. In the case of a solid image, it is sufficient if the density of the copied image can be obtained in proportion to the density of the original image, but in the case of a line image, the characteristic that the density of the copied image must be high is required regardless of the level of the original image density. Ru. In order to meet this demand, in a developing device that uses a -component type developer, a large number of microelectrodes are placed in an electrically floating state and dotted on the surface of the developing sleeve to create the so-called edge effect. Good development characteristics were obtained for both solid images and line images.

In a developing device that uses a one-component developer that can handle both solid images and line images, a large number of microelectrodes are exposed and disposed on the circumferential surface of the developing sleeve. A suppressing member is disposed so as to be able to press against the peripheral surface.

At the beginning of use of this developing device, the toner on the developing sleeve is pressed by the suppressing member and becomes a thin layer under layer thickness regulation.
Good development characteristics can be obtained. However, when the developing process is repeated, the following problems occur.

1) The insulating material separates and accumulates on the sleeve roller with a single helical action, significantly reducing its durability.

? ) The 1γ gap heat generated between the developing sleeve and the pressing member increases significantly and adheres to the surface of the developing sleeve or the pressing member, causing white streaks.

3) The amount of charge changes due to environmental changes, which disturbs the toner layer on the developing sleeve, resulting in uneven development.

OBJECTS It is an object of the present invention to provide a developer that solves the above-mentioned problems that occur when an electrostatic latent image is formed into a YA image using a thin toner layer formed by a developing sleeve and a suppressing member.

Structure The structure of the present invention to achieve the above object is a developer for electrostatic latent images containing a compound represented by the following general formula in a binder resin.

General Formula (2) However, X, Y, and Z are a hydroxyl group, a 21-robase, an acetyl group, a butyl group, or an acetyl-butyryl group.

General Formula (2) Where R=, R2, and R1 are a hydrogen atom, a methyl group, an ethyl group, a benzyl group, a trityl group, a cyanethyl group, or a carboxymethyl group.

By mixing the above-mentioned compound with the binder resin 1 to ner, the cohesive force of the toner increases, and as a result, it is thought that there is an effect that the low molecular weight components in the main polymer do not adhere to the sleeve roller.

Therefore, the problems of the prior art described above are solved.

The compound of general formula (1) above can be produced by reacting cellulose (pulp, linter, etc.) with nitric acid, acetic acid, acetic acid, etc. Further, the compound of the above general formula (1) is one in which part or all of the hydroxyl groups in the cellulose structure are etherified. For example, it can be produced by reacting cellulose with a halide such as ethyl chloride or trityl chloride, or by reacting an alkyl sulfate such as diether sulfate.

The appropriate proportion of the above compound in the binder resin is 2 to 30% by weight, preferably 10 to 20% by weight.

Various binder resins can be used for the image carrier of the present invention, including known resins. Some examples include styrene, parachlorostyrene, vinylnaphthalene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, etc. Vinyl esters, such as methyl acrylate, ethyl acrylate, in-butyl acrylate, isobutyl acrylate,
Dodecyl acrylate, 1ln-octyl acrylate, 2-chloro-ethyl acrylate, phenyl acrylate, α-
Esters of α-methylene aliphatic monocarboxylic acids such as methyl chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl Polymers obtained by polymerizing monomers such as vinyl ethers such as ethers, vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone, and N-vinyl compounds such as N-hinylpyrrole and N-vinylcarbazole, or monomers thereof. copolymers or mixtures thereof, such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyurethane resins, cellulose resins,
Examples include non-vinyl resins such as non-vinyl thermoplastic resins such as polyether resins, or mixtures of these and vinyl resins as described above.

In addition, the following materials are particularly limited to pressure fixing materials.

Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide, polytetrafluoroethylene, etc.), epoxy resin, polyester resin (oxidation 10 or less), styrene-butadiene copolymer (monomer ratio 5 to 3)
0:95-70), olefin copolymers (ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic ester copolymer, ethylene-vinyl chloride copolymer) polymers, ethylene-vinyl acetate copolymers, ionomer resins), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymers, maleic acid-modified phenol resins, phenol-modified terpene resins, and the like.

In addition to the resin, optional coloring agents such as pigments and dyes may be added to the toner of the present invention, if necessary. These colorants are common λ0, such as carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue,
DuPont oil red, quinoline yellow, medilene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, oil black, azo oil black, rose bengal and mixtures thereof.

In addition, when used as a toner containing a magnetic material, the magnetic material is chemically stable and the particle size is 1.
Magnetite (triiron tetroxide) is the most preferable because it is preferable to use a material that can be easily obtained in the form of fine particles with a size of μ or less.

Typical magnetic or magnetizable metals include metals such as cobalt, iron, and nickel; aluminum, cobalt, copper, iron, lead, magnesium, nickel, tin, zinc, antimony, beryllium, bismuth, cadmium, Calcium, manganese, selenium, titanium, tungsten,
Alloys of metals and mixtures thereof such as vanadium; metal compounds including metal oxides such as aluminum oxide, iron oxide, copper oxide, nickel oxide, zinc oxide, titanium oxide, and magnesium oxide; vanadium titanide, chromium titanide Refractory titanides such as; carbides such as tungsten carbide and silicon carbide; and mixtures thereof can be used.

These ferromagnetic materials preferably have an average particle size of about 0.1 to 1 μm, and are incorporated in the toner in an amount of about 50 to 300 parts by weight per 100 parts by weight of the resin component, particularly preferably in an amount of about 50 to 300 parts by weight per 100 parts by weight of the resin component. It is 90 to 200 weight parts per 100 weight parts.

For example, when the purpose is a color magnetic toner, γ-Fe
A 2Q3 type brown magnetic material is used, or a magnetic powder whose color is hidden by surface treatment is used.

Further, the toner of the present invention can be used together with a fluidizing agent if necessary, and the fluidizing agent is preferably a fine powder of hydrophobic silica, titanium oxide, aluminum oxide, etc., and the amount used is within the range of the toner. It is preferably 0.1 to 1% by weight.

A method of forming an image by electrophotography using the toner of the present invention will be described below.

As a photoreceptor, a selenium photoreceptor, a selenium telluride photoreceptor, or an inorganic photoconductive material such as zinc oxide, cadmium sulfide, cadmium selenide, cadmium selenide sulfide, lead oxide, or mercury sulfide is dispersed in a binder resin. A photoreceptor or an organic photoconductive material such as anthracene, anthrone, poly-N-vinylcarbazole, etc. is provided on a conductive support via an intermediate layer made of casein treated with ammonia as necessary. A photoreceptor is used in which a photoreceptor layer containing a binder resin is provided on a conductive support via an intermediate layer made of casein or a water-soluble polymer compound as required. The shape of the photoreceptor may be a drum, a plate, or a belt.

The surface of the photosensitive layer of these photoreceptors is first charged by corona discharge using, for example, a corotron or scorotron charger, and then imagewise exposed to light or the like to form an electrostatic latent image on the surface of the photosensitive layer. The electrostatic latent image thus formed is developed using a developing device as shown in the accompanying drawings.

FIG. 1 shows a developing device using magnetic toner, in which a developing sleeve 2 has numerous microelectrodes 5 on the surface of an insulating holding member 4.
is provided so as to surround the magnet 3.

When this developing sleeve rotates in the direction of arrow B, the pressing member 6
The toner is charged by friction with the developing sleeve 2, and a thin charged toner layer 1 is formed on the surface of the developing sleeve 2. With this toner, a latent image formed on the surface of the photoreceptor rotating in the direction of the arrow is developed.

FIG. 2 shows a developing device using non-magnetic toner, which operates in the same manner as the device shown in FIG. 1 above, except that toner is supplied from a toner supply roller 7.

The toner image developed in this manner is transferred to a transfer member under corona discharge, for example, or by pressure transfer. The toner image transferred to the transfer member is fixed thereon by, for example, a hot plate fixing method, a hot roll fixing method, a pressure fixing method, or a flash fixing method. The same treatment can be applied to cases where latent images for electrostatic recording are created by methods other than electrophotography.

This invention will be explained below with reference to Examples, but the embodiments of this invention are not limited thereto.

In addition, the proviso (parts) for each component described in the examples is parts by weight.

Example 1 Toner composition Polystyrene 100 parts Carbon black 10 parts Magnetite (0.1μ)
100 parts Nigrosine EX [Orient Chemical Industry■
] 2 parts Cellulose acetate butyrate 20 parts The above-mentioned material was heated and kneaded using a heating roll, cooled, crushed and classified to obtain a magnetic toner having a volume average particle size of 12 μm and an electrical resistance of 4×10”0 cm.

This toner was put into an electronic copying machine equipped with a developing device as shown in FIG. 1, and a durability test and an environmental test were conducted.

In the durability test, 60,000 copies were made, but no abnormalities occurred. Environmental test: 15°C, 110% RH and 35°C.
In an atmosphere of 85% RH, there was no decrease in image density and no image unevenness occurred.

Comparative Example A magnetic toner was made under the same conditions as in Example 1, except for the cellulose acetate, and the same test as in Example 1 was conducted. After 20,000 copies were made, the toner did not hold up against the sleeve. Adhesion occurs at 15°C11
In the atmosphere of o%R+-1, image unevenness occurred.

Example 2 Toner composition Polyester resin 100 parts Carbon black 10 parts Nigrosine LX [Orient Chemical Co., Ltd. ■ 12 parts Cellulose acetate 20 parts A toner was prepared from the above materials in the same manner as in Example 1, and a non-magnetic powder with a volume average particle size of 12 μm was prepared. Got toner.

This toner was put into an electronic copying machine equipped with the developing device shown in FIG. 2, and the same test as in Example 1 was conducted.
Similar to Example 1, good results were obtained.

Example 3 Composition of toner Epoxy resin 100 parts Phthalocyanine blue 5 parts Nigrosine EX [Orient Chemical Industry ■] 2 parts Nitrocellulose 15 parts A toner was prepared from the above mixture in the same manner as in Example 1. 1 n of magnetic toner was added.

When the same test as in Example 2 was conducted using this toner, good results as in Example 1 were obtained.

Example 4 Durability test 1 was conducted under the same conditions as Example 1 using a toner having the same composition as Example 1 except that methyl cellulose was used instead of cellulose acetate butyrate.
We conducted an environmental test.

The results were the same as in Example 1, with no decrease in image density and no unevenness of image.

Example 5 A toner having the same composition as Example 2 except that ethyl cellulose was used instead of cellulose acetate was used, and a durability test and an environmental test were conducted under the same conditions as Example 1.

As with Example 1, good results were obtained.

Example 6 A toner having the same composition as Example 3 except that benzyl cellulose was used instead of nitrocellulose was used, and a durability test and an environmental test were conducted under the same conditions as Example 1.

The results were as good as in Example 1.

Effects As explained above, the developer of the present invention does not adhere to the sleeve even when a large number of continuous copies are made, and does not cause image unevenness even in a high temperature and high humidity atmosphere. Ta.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a developing device using magnetic toner, and FIG. 2 is an explanatory diagram of a developing device using non-magnetic toner. 1... I ~ Luna-2... Developing sleeve, 3... Magnet, 4... Insulating holding member, 5... Microelectronic (*, 6
... Suppressing member, 7... Photoreceptor, 8... Toner replenishment roller. Patent applicant Rico Co., Ltd. - Agent Patent attorney Hide Komatsu Agent Patent attorney Hiroshi Asahi Figure 1 Figure 2

Claims (1)

[Scope of Claims] A developer for electrostatic latent images, characterized in that a binder resin contains a compound represented by the following general formula I or II. General Formula I ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, X, Y, and Z are hydroxyl groups, nitro groups, acetyl groups, butyl groups, and acetyl/butyryl groups. General Formula II ▲There are numerical formulas, chemical formulas, tables, etc.▼ However, R_1, R_2, and R_3 are hydrogen atoms, methyl groups, ethyl groups, benzyl groups, trityl groups, cyanethyl groups, or carboxymethyl groups.