JP2934472B2 - Toner for developing electrostatic images - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a toner for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like. Is related to a binder resin.

[Related Art] Generally, in electrophotography, electrostatic recording, or the like, development is performed to develop an electrostatic latent image formed on a latent image carrier made of a photoconductive photoreceptor or a dielectric. It is thinned by a blade etc. on a toner supply roller such as a sleeve,
The toner image is developed by using an appropriately charged and finely powdered toner, and if necessary, a toner image is transferred to a transfer material such as paper, and then fixed by heating pressure, a solvent vapor, etc. to obtain a copy. is there.

As a developing method applied to these electrophotographic methods and the like,
Broadly, there are a dry development method and a wet development method. The former is further divided into a method using a two-component developer and a method using a one-component developer. Among the two-component developing methods, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, a fur brush method using fur, and the like, depending on the type of the carrier that carries the toner.

In addition, those belonging to the one-component developing method include a powder cloud method in which toner particles are used in a spray state, and a contact developing method in which toner particles are brought into direct contact with an electrostatic latent image surface for development (contact development or toner development). Developing), a jumping development method in which the toner particles are charged and fly toward the latent image surface by an electric field of the electrostatic latent image without directly contacting the toner particles with the electrostatic latent image surface. There is a magnedry method or the like in which development is performed in contact with the electrostatic latent image surface.

In the toner applied to these developing methods, low-molecular-weight polyethylene or polypropylene is mixed as a releasing agent in order to improve the offset property in a fixing portion. Since these release agents have poor compatibility with polystyrene, which is often used as a binder resin, phase separation occurs during kneading. At the interface due to the phase separation, there is a phenomenon in which a mechanical force is easily applied to cause destruction and the toner is pulverized. For example, at the contact surface between photoconductive photosensitive and paper,
Or, it occurs at the contact surface between the developing sleeve and the blade and further at the contact surface between the developing sleeve and the photoconductive photoconductor.

In the case of the contact development method, for example, in the case of the contact development method, the toner adhering to the developing sleeve causes a fusing phenomenon over time and causes filming on the developing sleeve. When the filming phenomenon is observed on the developing sleeve, the thickness of the thinned toner layer becomes non-uniform, and the non-uniform distribution of the charge amount during the development of the electrostatic latent image → per unit area on the developing sleeve. Non-uniformity in the amount of adhered toner → As a result, shading also occurs on the copy, which is a very problematic image. The pulverization of the toner caused by the brittleness of the toner particles means that the toner is easily pulverized by mechanical force, which is preferable from the viewpoint of the productivity of the toner. Therefore, in order to avoid the above-mentioned filming phenomenon, it is conceivable to use a polymer having a high molecular weight.However, in consideration of heat fixing of an image which is usually performed in the final step of copying or printing, a fixing temperature is increased. Since a large amount of heat is required for fixing, it is not preferable for energy saving or for downsizing of hardware devices. Further, it has been proposed to add a small amount of a plasticizer to the toner for the purpose of resolving this phenomenon. However, there is a problem that the free flowing property of the toner is impaired and the carrier is contaminated. I haven't. Also, if the toner is too hard, mechanical pulverization becomes impossible,
Kneading may not be sufficiently dispersed.

Heretofore, relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymer, which can have appropriate hardness for the above reasons, has been used as a binder resin for toner. However, in the case of a device such as a laser printer that requires an electrophotographic system and requires maintenance-free, the relatively low molecular weight polystyrene or styrene-butyl methacrylate copolymer is not sufficiently hard, and the hardness is further increased. It has turned out that expensive materials are needed. In addition, this type of binder resin has insufficient properties in thermal fixing by a hot roll, which is widely used at present, and although the toner binder resin is melted by heat and has good adhesion to paper, etc. , An offset phenomenon to the heat roller is observed.

Further, a fluidization accelerator is often used to suppress filming on a developing roller or a photoconductor or spent on a carrier. For example, JP-A-47-36405, JP-A-47-36830
Uses metal soap. In JP-A-52-153441 and JP-A-53-147541, fluorine compounds are used, in JP-A-54-8534, nonionic surfactants are used, and in JP-A-56-62256, silica whose surface is hydrophobized is used. Have been. JP-A-56-668
In 56, particles harder than the toner are embedded in the toner surface, in JP-A-58-134651, an ion exchange resin is contained in the binder resin, and in JP-A-59-131943, as a release agent Using oxidized polyethylene, a mold release effect is exhibited while having compatibility with the binder resin. In JP-A-56-197048, a silicone oil is contained in a binder resin, in JP-A-59-220748, wax fine particles are externally added to a toner, and in JP-A-60-138565, carbon black is added. In addition, the resistance of the toner is reduced. JP-A-60-186851, JP-A-60-186852, JP-A-60-186853, JP-A-60-186854, JP-A-60-186855, JP-A-60-186857,
JP-A-60-186858, JP-A-60-186860, JP-A-60-18686
1, JP-A-60-186862, JP-A-60-186863, JP-A-60-1868
64, JP-A-60-186865 and JP-A-60-186866, polymer fine particles are externally added. In Japanese Patent Application Laid-Open No. 61-99164, an effect of suppressing filming on a developing roller and a photoreceptor and spent on a carrier is exhibited by an additive by externally adding an abrasive (SiC, SiN). However, the effects described above are not yet sufficient with these additives alone, and it is considered that the best method is to avoid filming and spent by improving the polymer which is also the main component of the toner.

[Problems to be Solved by the Invention] The present invention suppresses the pulverization of toner particles on a photoreceptor and a developing sleeve.
Filming on the developing sleeve and photoconductor due to frictional heat between the developing sleeve and the blade is suppressed, and spent on the carrier and sticking to the blade are suppressed. It is an object of the present invention to provide a toner for developing electrostatic charge.

[Means for Solving the Problems] The constitution of the present invention for solving the above-mentioned problems is as follows. In the toner comprising at least the binder resin and the colorant, the composition ratio of the toner surface structure is determined by the fact that the polypropylene component is less than the value measured by ESCA. 5% or more and 60% or less, and the polystyrene component is 10% or more and 50% or less, and in a sea-island structure formed by the base polymer and the polypropylene on the toner surface, the maximum diameter of the polypropylene island portion is 5000 mm or less. This is a toner for developing an electrostatic image.

In order to measure the structural composition ratio of the toner surface, X-ray electron spectroscopy ESCA (Electron Spectroscopy for Chem
ical Analysis). This apparatus is an optimal method for quantitatively observing the chemical structure of the surface of an organic compound, and is a surface analysis method that has been frequently used in recent years.
The information obtained here is that peaks from various elements are obtained by the difference in binding energy, and broad peaks are detected as measured values.However, waveform separation is performed by computer processing, and peaks due to certain elements are detected. Are separated into many bound state peaks. Therefore, measuring C ₁₈ on the toner surface reveals the toner surface composition,
From this value, the amount of orientation of polypropylene and polystyrene on the toner surface can be determined. The measurement was carried out without fixing the toner on a glass substrate with a double-sided tape and sputtering the toner surface. As a method of measuring the island shape of polypropylene, the toner is sampled to a thickness of about 1000 mm in the same manner as when a toner is measured with a normal transmission electron microscope (TEM), and then the osmium tetroxide solution is used at 60 ° C. × 3.
Time staining was performed. The obtained toner sample was observed with a TEM, and the maximum diameter in the major axis direction of the island-shaped polypropylene was measured.

In the toner surface structure, the composition ratio of polypropylene is
If it is less than 5%, an offset phenomenon occurs during fixing with a heat roller, and if it is more than 60%, a filming phenomenon appears on the developing sleeve and the surface of the photoconductor. On the other hand, if the maximum diameter of the island-shaped portion of the polypropylene is 5000 mm or more, filming occurs on the developing sleeve and the surface of the photoreceptor.

The monomers forming the binder resin used in the present invention include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene, p
-Tert-butylstyrene, pn-hexylstyrene,
pn-octyl styrene, pn-nonyl styrene,
pn-decylstyrene, pn-dodecylstyrene,
styrenes such as p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl chloride; vinylidene chloride; Vinyl halides such as vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl acetate; methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, and methacrylic acid Α-methylene aliphatic monocarboxylic acid esters such as ethyl, vinyl ethers such as vinyl methyl ether, vinyl ketones such as vinyl methyl ketone, N-vinyl pyrrole, N-vinyl carbazole, N
-N-vinyl compounds such as vinylindole and N-vinylpyrrolidone. These monomers can be used alone or in combination of two or more.

Further, as a monomer for forming a polycondensation type resin,
Ethylene glycol, triethylene glycol, 1,2-
Polyhydric alcohols such as propylene glycol, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene oxidized bisphenol A, etc., polyamines such as ethylenediamine, tetramethylenediaminepiperazine, and maleic acid,
Fumaric acid, mesaconic acid, citraconic acid, adipic acid,
Examples thereof include malonic acid and esters thereof with acid anhydrides or lower alcohols. Further, the present invention is not limited to the resin monomers shown here.

In the toner of the present invention, additives such as a coloring agent and a charge controlling agent can be used. Examples of such additives include metal chelate dyes such as carbon black, oil black, nigrosine dyes, and metal-containing dyes, aniline dyes, and calco oil. Blue, chrome yellow, ultramarine blue, methylene blue chloride, phthalocyanine blue, rose bengal, and other dyes or pigments are included.

As a method for producing the toner in the present invention, for example, polyphenylene ether, polystyrene and acrylic resin,
When a mixed composition of low molecular weight polypropylene and carbon black, a charge controlling agent was kneaded and pulverized, and the toner obtained by classification was used to produce an image, the image was formed on the photoconductive photoconductor or the developing sleeve. No finely powdered and adhered toner was observed, and no state was observed in which the adhered toner was thinned to form a film. As a result, the toner is uniformly layered on the developing sleeve, and the development on the photoconductive photoconductor is performed uniformly.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples. The amounts (parts) of the components described in the examples are parts by weight.

Example 1 Styrene / butyl methacrylate = 8/2 65 parts Polyester 30 parts Polypropylene 5 parts Di-tert-butyl-salicylate zinc salt 4 parts Carbon black 5 parts After kneading with a ruder, the mixture was pulverized and classified to obtain a toner having an average particle diameter of 10 μm.

When the surface composition was measured by ESCA, polypropylene was 26.
% And polystyrene was 35%. The maximum island-shaped diameter of polypropylene was 1800 mm.

FIG. 1 of the accompanying drawings is a schematic cross-sectional view of an example of a developing device using the non-magnetic-component toner of the present invention. As shown in FIG. 1, the toner 6 contained in the toner tank 7 is
Is forcibly brought to a sponge roller (toner replenishment auxiliary member) 4 by a stirring blade (toner replenishment auxiliary member) 5 and toner is supplied to the sponge roller 4. When the sponge roller 4 rotates in the direction of the arrow, the toner taken into the sponge roller 4 is conveyed to the toner conveying member 2 and is rubbed and electrostatically or physically attracted. , And the steel elastic blade (toner layer thickness regulating member) 3 forms a uniform thin toner layer and is triboelectrically charged. Thereafter, the latent image is transported to the surface of the electrostatic latent image carrier 1 that is in contact with or approaching the toner conveying member 2 to develop the latent image. The developing device suitable for the toner of the present invention is not limited to the above.

When this toner was used to develop an image using a developing device as shown in FIG. 1, a good image was obtained, and the image remained unchanged after 100,000 sheets of running. The charge amount at the beginning of running was −12.8 μc / g, and after running, it was almost unchanged at −11.7 μc / g. Also, no filming was observed in which the toner adhered and melted on the photoconductive photoreceptor surface or the developing sleeve surface.

Example 2 65 parts of styrene 10 parts of methacrylic acid 20 parts of n-butyl methacrylic acid 20 parts of polypropylene 5 parts of 100 parts of at least three kinds of polymers 4 parts of zinc di-tert-butyl-salicylate 4 parts of carbon black 6 parts or more of a substance is extracted. After kneading with a ruder, the mixture was pulverized and classified to obtain a toner having an average particle diameter of 11 μm. The surface composition measured by ESCA was 22% for polypropylene and 31% for polystyrene. The maximum island-shaped diameter of polypropylene was 1600 °.

When this toner was used to develop an image with a developing device as shown in FIG. 1, a good image was obtained, and the image did not change even after the running of 80,000 sheets. The charge amount at the beginning of running was -9.2 µc / g, and after running, it was almost unchanged at -9.3 µc / g. Also, no filming was observed in which the toner adhered and melted on the photoconductive photoreceptor surface or the developing sleeve surface.

Example 3 40 parts of styrene 5 parts of methacrylic acid 5 parts 45 parts of n-butyl methacrylic acid 5 parts of 2-ethylhexylacrylic acid 5 parts of polypropylene 5 parts of above three kinds of polymers 100 parts of zinc di-tert-butyl-salicylate 6 parts carbon black 10 parts or more of the substances were kneaded with an extruder, pulverized and classified to obtain a toner having an average particle diameter of 10 μm. When the surface composition was measured by ESCA, polypropylene was 20% and polystyrene was 38%. The maximum island-shaped diameter of polypropylene was 1750 °.

When this toner was used to develop an image using a developing device as shown in FIG. 1, a good image was obtained, and the image remained unchanged after running 200,000 sheets. The charge amount at the beginning of running was -13.7 μc / g, and after running, it was almost unchanged at −13.5 μc / g. Also, no filming was observed in which the toner adhered and melted on the photoconductive photoreceptor surface or the developing sleeve surface.

Comparative Example 1 The toner was kneaded with two rolls using the compounding ratio of Example 1, pulverized and classified, and then an image was formed using a developing device as shown in FIG. 1. As a result, a good image was obtained. I couldn't. The image became worse after running 10,000 copies.
The charge amount at the beginning of the running was -8.7 µc / g, and after the running, it changed to -2.3 µc / g, which is about 4 µc / g. Also, toner adheres to the photoconductive photoreceptor surface or the developing sleeve surface,
Melted filming was remarkably observed.

The surface composition of the toner was measured by ESCA and found to be 70% for polypropylene and 7% for polystyrene. The maximum diameter of the islands of polypropylene was 5,600 mm.

[Effects of the Invention] As described above, the toner of the present invention suppresses filming on a photoreceptor, spent on a carrier, and sticking to a blade, and can permanently form a good copied image.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a developing device using the toner of the present invention. 1 .... Electrostatic latent image carrier, 2 .... Toner conveying member, 3 ....
Elastic blade, 4 sponge roller, 5 stirring blade, 6 toner, 7 toner tank.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/08

Claims (1)

(57) [Claims] 1. A toner comprising at least a binder resin and a colorant, wherein the composition ratio of the toner surface is 5% or more and 60% or less and the polystyrene component is 10% or less as measured by ESCA. Not less than 50%,
A toner for developing an electrostatic charge image, wherein in a sea-island structure formed by a base polymer and polypropylene on the surface of a toner, the maximum diameter of a polypropylene island portion is 5000 mm or less.