JPS61188549A - Formation of image - Google Patents

Abstract

PURPOSE:To ensure high fluidizability and stable electrification development characteristics of a toner by mixing fine particles as a fluidizing agent electrifiable to a polarity same as that of the surface charge of an image bear ing body with the toner. CONSTITUTION:The fine particles as a fluidizing agent electrifiable to apolarity same as that of the surface charge of an image bearing body are mixed with the toner in an amt. of 0.1-2 wt. % of the toner, and they are made of an oxide of a metal, such as Al, and have an average particle diameter of 5-100 mum. When added too small, a fluidizing effect is deteriorated, and when added too much, action for grinding and removing matters attached to the surface of the image bearing body is not exhibitted, thus permitting the surface of the image bearing body to be cleaned well, not to need to be coated with a metal soap film, and sharp images high in density to be always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to image forming methods such as electrophotography, electrostatic printing, and electrostatic recording.

Conventional technology For example, in electrophotography, an electrostatic latent image is usually formed by charging and exposing an electrostatic image support made of a photoconductive photoreceptor, and then this electrostatic latent image is transferred to an electrostatic image support made of a binder resin. Developed with a toner formed by containing a colorant in fine particles, and the resulting toner image is transferred to a support such as transfer paper, and then fixed by heating, pressure, etc. to form a visible image. .

As a photoreceptor, a selenium photoreceptor, which is used for positive charging, is known. In this case, for the purpose of improving the fluidity of the toner, negatively charged silicon, 'J (average particle size 10-100
Mu) is often used by mixing a small amount (0.1 to 1.0 fCf%) with toner. When such silica adheres to the surface of the toner, direct contact between the toner and the photoreceptor is eliminated, so the adhesion force between the toner and the photoreceptor is reduced, and electrostatic transfer to transfer paper is facilitated.

However, if the silica released from the toner adheres to the surface of the photoreceptor alone, the adhesion force to the surface of the photoreceptor is too strong, making cleaning impossible and causing a phenomenon in which silica is deposited on the surface of the photoreceptor. Therefore, it is necessary to take measures to prevent direct contact between the silica and the photoreceptor by supplying silica such as zinc stearate to the surface of the photoreceptor to form a thin film.

That is, a means for supplying metal soap such as zinc stearate is required, which complicates the mechanism, and it is difficult to control the thickness of the zinc stearate coating, and if the coating is formed too thick, the photoreceptor properties will be impaired. Image defects such as image blur and decreased density may occur. Moreover, since metal soap promotes the crystallization of selenium and selenium-tellurium photoreceptors,
While it shortens the life of the photoreceptor, it is excellent in heat resistance.

In the case of As, Se3, or amorphous St, if a film of metal soap such as zinc stearate is formed on the surface, image blurring will occur, which is inappropriate.

An object of the present invention is to provide an image forming method capable of realizing high fluidity of toner and stable charging and developing characteristics without forming a metal soap film on an image carrier. There is a particular thing.

29 Structure of the invention and its effects, that is, the present invention uses a toner for developing an electrostatic image in which fine fluidizing agent particles that can be charged to the same polarity as the surface charge of an image carrier (for example, a photoreceptor) are added and mixed. The present invention relates to an image forming method including a step of developing the electrostatic charge image on the image carrier.

According to the present invention, since the toner is mixed with fluidizing agent fine particles that can be charged to the same polarity as the surface charge on the image carrier, the fluidizing agent is applied to the image carrier while improving the fluidity of the toner. Since the adhesion of the fine particles is relaxed, they can be cleaned well, and there is no need to form a metal soap film on the image carrier. For this reason, high-density, clear images can always be obtained, and stable charging and developing performance can be obtained.

This is because the fluidizing agent fine particles used are made of a metal oxide such as aluminum oxide, and the average particle size is 5 to 5.
This can be fully realized by setting it to 100 mμ.

In this particle size range, it is possible to sufficiently generate abrasive force (surface polishing of the image carrier) while maintaining good toner fluidity, especially when the particle size is relatively large. In this case, in the toner of the present invention, since the fluidizing agent fine particles can be charged to the same polarity as the image carrier, there is little electrostatic adhesion and deposition on the surface of the image carrier, and as a result, it is possible to add a large amount to the toner. It becomes possible. Therefore, the abrasive effect exerted by the fluidizing agent fine particles can be effectively brought out by adding a large amount to the toner, and it is possible to prevent toner filming on the surface of the image carrier.

In the present invention, a positively charged selenium photoreceptor, a selenium-tellurium photoreceptor, an amorphous silicon photoreceptor, or the like can be used as the image carrier. Examples of metal oxide fine particles as a fluidizing agent that exhibit positive chargeability include aluminum oxide. In particular, aluminum oxide which has a hydrophobically treated surface and has an average particle size of 5 to 100 m[mu], preferably 10 to 30 m[mu] can be cited as a material that can be externally added to toner and has a remarkable effect of improving fluidity. As an example, rAlua+inium Oxid manufactured by Nippon Aerosil Co., Ltd.
e CJ (average particle size 20 mμ).
,.

In this case, as the fluidizing agent fine particles, preferably small particles with an average particle size of 10 mμ or less can achieve high fluidity, and large particles with an average particle size of 20 mμ or more can exert sufficient polishing power. For the first time, we are able to provide toner that has both these properties.

Figure 1 shows the relationship between the average particle size of the fluidizing agent (e.g. silica) particles added to the toner and the quietness density of the toner, and Figure 2 shows the average particle size of the abrasive particles (e.g. silica). The relationship between the diameter and the amount of surface polishing of a selenium-tellurium photoreceptor by toner is shown.

In this case, the amount of particles such as silica added is 0.8 parts by weight, the binder resin of the toner is polyester resin, the average particle size of the toner is 9 μm, and the carrier is a styrene acrylic resin film on spherical iron powder with an average particle size of 120 μm. It is coated to a thickness of 2 μm, and the amount of polishing is the value after 3 hours. From Figures 1 and 2, the average particle size of the added particles is 5 to 1.
If selected appropriately within the range of 00 mμ, the quietness and density will improve and the fluidity of the toner will increase, but the amount of polishing (i.e., uniformly polishing the surface of the photoconductor by rubbing with a magnetic brush) will increase (become For example, if small particles with an average particle diameter of 10 mμ or less and large particles with an average particle diameter of 20 mμ or more are mixed and used, a toner with sufficient fluidity and polishing amount can be created, and the particles It is possible to increase the amount of polishing while maintaining fluidity even if the amount added is small.However, the lower limit of the average particle size of small diameter particles is 5 mμ, and the upper limit of the average particle size of large diameter particles is 100 mμ. is desirable.

Here, the above-mentioned "average particle diameter" is determined from a specific surface area measurement value determined by a method called the BET method.

In addition, the "quietness density" is measured using Seishin's Tuff Denser, which measures toner particles in a 100 cc cylinder.

The amount of the fluidizing agent fine particles externally added to the toner is 0.1 to 2.0 parts by weight, preferably 0.2 to 1.0 parts by weight, per 100 parts by weight of the toner. If the amount of external addition is small, the effect of improving fluidity will be weak, and the effect of polishing and removing deposits on the surface of the photoreceptor will not be exhibited. On the other hand, if it is added in an appropriate amount, the effect on the charge amount of the toner becomes significant, the dependence of the charge amount on humidity becomes large, and the surface damage of the photoreceptor occurs due to excessive polishing action.

The present invention can be applied to both one-component and two-component developers. The carrier used in the two-component developer may be conductive, insulating, irregularly shaped, or spherical.
stomach.

As the binder resin constituting the toner according to the present invention, the following can be used.

Styrene-acrylic resin: Weight average molecular weight/number average molecular weight = 3.5 to 40, number average molecular weight is 2,000 to 30,000. Divinylbenzene, etc. can be used as a crosslinking agent.

A condensation polymer of polyester resin diol and dicarboxylic acid,
Polyhydric carboxylic acids and acid anhydrides with higher valences are used to increase the offset prevention effect as a three-dimensional structure (for example, polyester resins disclosed in JP-A-57-37353).

Styrene-butadiene resin: A resin containing 20% by weight or less of a component with a molecular weight of 100,000 or more, and 15% by weight or less of a component with a molecular weight of 500,000 or more (for example, Japanese Patent Application Nos. 56-35168, 56-35169, 56-3)
5170, 56-35171, 56-35172, and 56-35173).

In addition to the above, known binder resins for electrophotographic toners such as known epoxy resins and butyral resins can be used as appropriate.

In addition to divinylbenzene, crosslinking agents for the binder resin include divinylnaphthalene, diethylene glycol diacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, allyl methacrylate, t-butylaminoethyl methacrylate, tetraethylene glycol dimethacrylate, 1.3- Butanediol dimethacrylate, ethylene glycol dimethacrylate, tetramethylolmethane tetraacrylate, N,N-divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone, etc. can be used. The crosslinking agent is o, o for the polymerizable monomer of the binder resin.
os to 20% by weight (preferably 0.1 to 5% by weight) may be added.

In addition, usable colorants include carbon black,
Examples include nigrosine, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, rose bengal, etc., and the amount added depends on the binder resin. It may be 1-20% by weight.

Additionally, other substances may be added to the toner to improve its properties. As anti-offset agents that can be added, low softening point polyolefins such as polypropylene and polyethylene (
It may be either a homopolymer or a copolymer. The softening point is 80-180°C when measured by the ring and ball method according to JIS Standard 2531-1960.
°C is preferred. ), known fatty acid metal salts such as zinc salts of maleic acid, fatty acid esters such as maleic acid ethyl ester, partially saponified fatty acid esters such as calcium partially saponified products of Moncnic acid ester, higher fatty acids such as dodega) acid, Higher alcohols such as lauryl alcohol, liquid solid paraffin wax, amide waxes such as stearic acid amide, polyhydric alcohol esters such as glycerin stearate, silicone fabrics such as methyl silicone fabrics, JAW aliphatic fluorocarbons such as tetrafluoroethylene, etc. Can be mentioned. The ratio of the offset inhibitor to the binder resin is preferably 0.5 to 20% by weight, preferably 1 to 10% by weight.

In order to further improve the fluidity of the toner of the present invention, a suspension polymerization method or a granulation polymerization method (using a water-soluble polymer such as gelatin or fine powder of a poorly water-soluble inorganic compound such as barium sulfate as a dispersion stabilizer) ), the toner is made into spheres by spray drying (hot air treatment) the crushed toner.

Also, carriers can be used in combination with toners according to the present invention.

FIG. 3 shows an example of an apparatus for carrying out the method according to the present invention. In this method, positively charged amorphous selenium
In an electrophotographic copying machine 41 incorporating a photoreceptor drum 9 made of tellurium, a document 42 is placed in the upper part of the cabinet 30.
A glass document mounting table 43 on which the document is placed, and a platen cover 44 that covers the document 42 are arranged. Below the document table 43, an optical scanning table consisting of a first mirror unit 47 equipped with a light source 45 and a first reflection mirror 46 is provided so as to be movable in a straight line in the left and right direction of the drawing. a second mirror unit 2 for keeping the optical path length constant;
0 moves in accordance with the speed of the first mirror unit, and the reflected light from the document table 43 passes through the lens 21, the reflection mirror, and the gicroic mirror 12, and is slit onto the photosensitive drum 9 as an image carrier. It is designed to be incident on the A corona charger 10, a developing device 11 with a built-in developing sleeve 18, a transfer section 52, a separation section 53, and a cleaning section 54 are arranged around the drum 9, and each paper feeding roller 16, 17 is arranged from a paper feeding box 55. Copy paper 58 sent through
After the toner image is transferred from the drum 9, it is further fixed in the fixing section 59, and then the paper is discharged to the tray 35. In the fixing section 59, a heating roller 23 with a built-in heater 22 and a pressure roller 2 are installed.
A fixing operation is performed by passing the developed copy paper between

E. Examples Next, the present invention will be described in detail, but the following examples can be variously modified based on the technical idea of the present invention.

(Preparation of toner) 299g of terephthalic acid and polyoxypropylene (2,
2) 211 g of -2,2-bis(4-hydroxyphenyl)propane and 82 g of pentaerythritol were placed in a round-bottomed flask equipped with a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a down-flow condenser. The flask was placed in a mantle heater, and nitrogen gas was introduced from the nitrogen gas inlet tube to raise the temperature while maintaining an inert atmosphere inside the flask. Next, dibutyltin oxide o and os g were added, and the reaction was allowed to proceed at a temperature of 200° C. while monitoring the reaction at the softening point, thereby producing a polyester resin with a chloroform-insoluble content of 17% by weight. This will be referred to as "polyester resin A."

Ring and ball softening point of this polyester resin A (JISK 13
According to the method of 51-1960. The same applies below. ) was 131°C.

100 parts by weight of the polyester resin A synthesized in the above synthesis example, 10 parts by weight of carbon black "Mogull LJ" (manufactured by Cabot Corporation), and 3 parts by weight of low molecular weight polypropylene "Viscol 660PJ (manufactured by Sanyo Chemical Co., Ltd.) were melt-kneaded, crushed and classified. Electrodetectable colored particles with an average particle diameter of 10 μm were obtained.These are referred to as toner X.

This toner
0.4 parts by weight was added and mixed to 100 parts by weight. This is called toner A.

The fluidity of the obtained toner was 0.392g/silence density.
It was cc.

Disaster plate l Toner
1.2 parts by weight was added and mixed to 100 parts by weight. This is called toner B.

The fluidity of the obtained toner was 0.432g/silence density.
It was cc.

Toner X was mixed with 0.4 parts by weight of silica (average particle size 20 mμ) that had been hydrophobized with hexadisilazane per 100 parts by weight of Toner X. Use this as toner.

The fluidity of this toner was 0.396 in quietness density.

Comparative Example 1 Toner L was obtained in the same manner as in Comparative Example 1 except that the amount of silica added was 1.2 parts by weight.

The fluidity of this toner was 0.434 in quietness density.

Toner L of Comparative Example 2 was mixed with 0.4 parts by weight of zinc stearate to obtain Toner M.

Toner X was used as it was without being treated with a fluidizing agent. The quietness density of this toner was 0.322 g/cc. A copy test was conducted using the above toners A, B, and L%MSN, and the image quality and image stability of the resulting copied images were investigated.

In this test, 2 parts by weight of toner and 100% average particle size coated with styrene-acrylic resin in a fluidized bed were used.
A developer was prepared by mixing with 98 parts by weight of mμ iron powder carrier, and this developer was used to produce an electrophotographic copying machine U-Bix 1600 equipped with a positively charged selenium-tellurium photoreceptor.
(manufactured by Konishiroku Photo Industry Co., Ltd.). The test results are shown below, and the environmental conditions were 33°C and 80°C.
%RH.

From the above results, it is clear that according to the method of the present invention, it is possible to suppress the occurrence of blank spots and toner filming, and to obtain stable images due to the high fluidity of the toner.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIGS. 1 and 2 are graphs showing the quietness density and polishing amount depending on the average particle size of additive particles, respectively, and FIG. 3 is a schematic cross-sectional view of an electrophotographic copying machine. It is. In addition, in the reference numerals shown in the drawings, 9...-----1---Photosensitive drum 1l-
-------・----------Developing device. Agent Patent Attorney Hiroshi Aisaka Figure 1 Figure 2 Flat angle a (mμ)

Claims (1)

[Claims] 1. An image comprising the step of developing an electrostatic image on the image bearing member using an electrostatic image developing toner in which fine fluidizing agent particles that can be charged to the same polarity as the surface charge of the image bearing member are added and mixed. Formation method.