JPH0572820A - Method for development of electrostatic latent image - Google Patents

Abstract

PURPOSE:To provide a developing method as same as a liquid developing method so that a developer is solid at normal temp. which makes handling easy, and to eliminate solvent odor or air pollution by using a developer in which a coloring agent is dispersed in a specified electric insulating org. material. CONSTITUTION:The developer consists of one of paraffins having 30-80 deg.C solidifying temp., wax or low mol.wt. polypropylene having 20-80 deg.C solidifying temp., fat having 20-50 deg.C solidifying temp. and hydrogenated oil having 30-80 deg.C solidifying temp. All of these are solid at normal temp. and contain dispersion of a coloring material. This developer is molten by heat to form a thin film on a conductive body. Then the thin film is brought into contact with or near an image carrier having an electrostatic latent image so that the coloring material moves by electrophoresis to form a visible image an image carrier due to the potential difference between the electrostatic latent image and a conductive body. The electric insulating org. material is specified to have >=20 deg.C solidifying point considering season, use environment and handleability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing an electrostatic latent image in an electrophotographic copying machine to form an image.

[0002]

2. Description of the Related Art Conventionally, latent electrostatic image developers include dry developers and wet development. A saturated hydrocarbon solvent is used for the wet developer. Further, JP-A Nos. 2-6963 to 6967 propose image forming methods using a solid-liquid change type liquid developer. This mainly considers development similar to liquid development with an ink ribbon.

[0003]

The saturated hydrocarbon solvent used in the conventional wet type developer has started to be regarded as a problem of environmental pollution in the office due to evaporation.
Further, the developer whose characteristics have deteriorated cannot be simply discarded, and recovery work is required. For these reasons, it is desired to use a substance that is harmless to the human body and the environment as the liquid developer. Furthermore, since it is liquid at room temperature, it is complicated and complicated to transport and handle. Usually contactor
And two kinds of solvent are supplied. Therefore, a space for stirring the developer is required to disperse the toner in the solvent in the copying machine.

The solid-liquid change type liquid developer has a higher viscosity than conventional liquid developers, and in order to improve the image quality, the developer should be made into a uniform thin layer and brought close to the image carrier. Must be used. The one proposed by the above-mentioned Japanese Patent Laid-Open No. 2-6963 is considered to be used like an ink ribbon. In such a method, as is the case with the thermal transfer method and the like, there are many parts that are discarded without using the ink, resulting in high cost.

[0005]

The present invention is a solid at room temperature, paraffins and waxes having a freezing point of 30 to 80 ° C, low molecular weight polypropylene having a freezing point of 20 to 80 ° C, freezing point of 20 to 50 ° C.
Of beef tallow or a hardened oil having a freezing point of 30 to 80 ° C is heated to form a thin layer on the conductor by heating the developer, which is then melted to form an electrostatic latent image. Characterized in that a visible image is formed on the image carrier by causing the coloring material to electrophorese due to the potential difference generated between the electrostatic latent image and the conductor by contacting or approaching the image carrier having This is an electrostatic latent image developing method. In the above description, each electrically insulating organic substance has a freezing point of 20 ° C. or higher in consideration of seasons and other usage environments and handleability. The upper limit is not particularly limited, but too high is not preferable because it consumes extra energy for heating. The temperature was set to 80 ° C. at most.

Suitable materials under such conditions include paraffins and waxes having a freezing point of 30 to 80 ° C. and a freezing point of 2
Low molecular weight polypropylene of 0 to 80 ° C, freezing point of 20 to
Examples include beef tallow at 50 ° C. and hardened oil at a freezing point of 30 to 80 ° C. These are solids around room temperature, and each has the property of liquefying when it exceeds the freezing point. This makes the toner
It is possible to provide a developer that is easy to replace and add, and that does not easily stain hands, clothes, office floors, and the like. In particular, beef tallow and hydrogenated oil are originally used as raw materials for foods, and therefore do not cause environmental pollution due to evaporation into the atmosphere. Further, it is advantageous that no special treatment is required even when the deteriorated developer is discarded.

Since these have a relatively high viscosity after melting, problems such as background stains and insufficient image density are likely to occur. Therefore, in order to prevent this point, a uniform thin layer should be formed on the conductor.
To 200 μm, preferably 50 to 150 μm. By doing so, it is easy to develop and it is possible to prevent the background stain from occurring. The method for forming the toner thin layer is not particularly limited, but it is preferable to form the toner thin layer with a gap provided between the conductor and the conductor by a regulation blade or a roller.

As the colorant dispersed in the developer, conventionally known inorganic pigments, organic pigments, dyes and mixtures thereof are used.

Examples of the inorganic pigments include chromium-based cadmium-based, iron-based, cobalt-based, ultramarine blue and dark blue. Examples of organic pigments and dyes include Hansa yellow (С, I, 11
680), Benzidine Yellow-G (C, I, 2109
0), benzidine orange (C, I, 21110), fast red (C, I, 37085), brilliant carmine 3B (C, I, 16015-Lake), phthalocyanimble (C, I, 74160), Victoria Bull- (C, I, 42595-Lake), Spirit Black (C, I, 50415), Oil Bull- (C,
I, 74350), Alkaline Bull- (C, I, 4277)
0A), first scarlet (C, I, 1231)
5), Rhodamin 6B (C, I, 45160), Rhodamin lake (C, I, 45160-Lake), Far
Stoskable- (C, I, 74200-Lake),
Nigrosine (C, I, 50415) and the like can be mentioned. These may be used alone or in combination of two or more.

As the developer, a resin may be used in combination with the above-mentioned electrically insulating organic substance and colorant for the purpose of improving dispersibility and fixing property of the colorant. For example, rubbers such as butadiene rubber and styrene-butadiene rubber, styrene-based, vinyltoluene-based, acrylic-based, methacrylic-based, polyester-based, polycarbonate-based, polyvinyl acetate-based synthetic resins, rosin-based, Examples thereof include hydrogenated rosin series, alkyd resins containing modified alkyd such as linseed oil modified alkyd, and natural resins such as polyterpenes. Other phenolic resins, modified phenolic resins such as phenol formalin resin, pentaerythritol phthalate, coumarone-indene resins, ester gum resins, vegetable oil polyamide resins, polyvinyl chloride, chlorine Halogenated hydrocarbon polymers such as modified polypropylene, synthetic rubbers such as vinyltoluene-butadiene, butadiene-isoprene, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, lauryl acrylate. Polymers of acrylic monomers having long-chain alkyl groups such as rates and octyl acrylates, copolymers of these with other polymerizable monomers, polyolefins such as polyethylene, and polyterpenes are also available. Can be used.

Further, a charge donor is added. For example, naphthenic acid, octenoic acid, oleic acid, stearic acid, metal salts of fatty acids such as isostearic acid or lauric acid, metal salts of sulfosuccinic acid esters, metal salts such as abietic acid, metal salts of aromatic carboxylic acids, Examples thereof include aromatic sulfonic acid metal salts. Further, in order to improve the charge of the coloring material, SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZnO,
Ga ₂ O ₃ , In ₂ O ₃ , CeO ₂ , SnO ₂ , PbO, Mg
Fine particles of a metal oxide such as O or a mixture thereof may be added as a charge enhancer.

The developer is used after being heated and melted if necessary. Any means may be used for heating the developer, but a method is preferred in which the presence or absence of heat radiation is easily controlled according to an input signal, for example, ON / OFF of energization. Also, the shape is a mesh,
The slit shape is preferable because it facilitates control of the amount of developer consumed.

FIG. 1 is an illustration of an example of the developing method of the present invention. Reference numeral 1 is an electrostatic latent image carrier such as a photoconductor. Reference numeral 2 denotes an opposite electrode of the electrostatic latent image carrier 1, which holds the developer 7 and brings it closer to the electrostatic latent image carrier 1. A heater 3 heats the counter electrode 2 to keep the developer 7 at a freezing point or higher. Reference numeral 4 denotes a heater for heating and melting the developer 7, which is a mesh in FIG. The developer is melted by heating and liquefied, and then flows out from between the meshes to the counter electrode 2 side. When the heating of the heater 4 is stopped after heating for a short time, the developer is cooled and solidified, and the replenishment is stopped. The developer that has flowed out in a small amount is kept in a molten state by the heat of the counter electrode 2, and the latent image on the electrostatic latent image carrier 1 can be wet-developed like the conventional wet developer. The consumption ratio of toner and toner carrier in the developer varies somewhat depending on the ratio of the white background portion of the original image, but unless the extreme white or black image is continuous, toner is usually used.
3 to 50% by weight of the total composition ratio, preferably 10 to 30
It can be dealt with by setting the weight%. If the toner concentration becomes abnormally high or low, it is detected by a sensor or the like used in conventional copying machines, the waste liquid discharge lid 6 is operated, and the developer 7 is discharged to the waste liquid receiver 5 And a new developer is obtained by operating the heater 4. If you are using a text manuscript normally used in the office,
By setting the toner ratio in the developer as described above, the injected developer can be consumed without excess or deficiency. Further, as for disposal, it may be processed by a usual disposal method of plastics, and it is not necessary to collect it specially like a conventional wet developer. The toner developed on the photoconductor is a corona charger.
It may be transferred onto the transfer paper by means of pressing, pressing or the like, and if necessary, it may be fixed by using fixing means such as heating, pressurizing, ultraviolet rays or electron beams.

FIG. 2 is an explanatory view of another example of the present invention.
First, the photo-semiconductor 8 is charged with a positive charge by the corona discharge by the charge wire 9, and the light is applied to the non-image part by the exposure part 10 to erase the charged charge. A developing roller 11 is installed in the optical semiconductor 8 at a certain interval, and a heater 12 is incorporated therein. The heater 12 heats the developing roller 11 and heats the developer 7 in contact with the developing roller 11 to the melting point or higher to liquefy the developer 7. The liquefied developer 7 forms a thin layer on the developing roller 11 by the regulating member 13, and enters between the optical semiconductor 8 and the developing roller 11. Here, the coloring material moves on the electrostatic latent image due to the potential difference generated between the charges on the optical semiconductor 8 and the developing roller 11,
It is developed. The developed image is transferred onto the transfer paper 15 by the electrostatic force by the charge wire 14. If necessary, the coloring material is fixed on the transfer paper by means of heating, pressing, etc., and an image is obtained.

[0015]

The present invention will be described in detail with reference to the following examples.

Example 1 The materials shown below were put into a ball mill and dispersed at 80 ° C. for 50 hours. All parts are parts by weight.

Paraffin wax (freezing point 40 ° C.) 100 parts Carbon black 20 parts Copolymer of methyl methacrylate and lauryl methacrylate 10 parts Stearic acid 5 parts Square columnar shape using a mold at high temperature Cooled and molded.

Next, the developing device as shown in FIG. 1 was loaded. Toner density of the developer was evaluated by measuring the image density on the developed photoreceptor. The surface temperature of the counter electrode 2 was set to 45 ± 2 ° C., and the heater 4 was heated to a surface temperature of 80 ° C. for 3 to 10 seconds to replenish the developer. The electrostatic latent image carrier 1 was also heated to set the surface temperature to 45 ± 2 ° C. When the developer 7 was used in this apparatus, the copied image was as clear as the conventional developer, and the toner was replenished by melting the developer little by little. Also, no solvent odor was felt.

Example 2 To 10 parts of carbon black, 80 parts of a lauryl methacrylate / methyl methacrylate (60/40) copolymer and 3 parts of zinc stearate were polypropylene (coagulation point 55 ° C.).
While being heated to 80 ° C. together with 100 parts, a batch type sand mill was used to perform dispersion treatment for 24 hours using stainless beads. Pour the resulting developer into a box at 25 ℃
It solidified when cooled to 0 ° C. to obtain a rectangular solid developer. This was placed in the developing device shown in FIG. 2 and developed. First, the surface temperature of the developing roller 11 was adjusted to 45 to 50 ° C. The distance between the developing roller 11 and the optical semiconductor 8 is about 50 .mu.m, and the regulating member 13 for regulating the thickness of the developer layer applied on the developing roller 11 is provided at an interval of about 60 .mu.m. .. A solid developer was placed on a guide plate provided beside the developing roller 11, and copying was performed by the same operation as in a conventional copying machine. The obtained copy is good and has fog on the background.
No bleeding was observed. Further, by stopping the heater 12 in the developing roller 11 and cooling it, the developer becomes a solid developer which can be easily handled during the stop, and the developer does not spill even when the machine is tilted.

Example 3 The procedure of Example 2 was repeated, except that beef tallow (melting point: 40 to 42 ° C.) was used instead of polypropylene in Example 2, and the mixture was heated to 50 ° C. The result was the same as in Example 2.

Example 4 The procedure of Example 2 was repeated, except that hardened oil (melting point: 40 to 42 ° C.) was used instead of polypropylene in Example 2, and the mixture was heated to 50 ° C. The result was the same as in Example 2.

[0022]

EFFECTS OF THE INVENTION The present invention is easy to handle because the developer is solid at room temperature while adopting the same method as the liquid developing method. Also, there is no concern about solvent odor or air pollution. Since the developer is used in the required amount little by little, the space in the copying machine can be saved and the apparatus can be made compact.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example of a developing device used for carrying out the present invention.

FIG. 2 is an explanatory view of another example of the developing device used for carrying out the present invention.

[Explanation of symbols]

 1 Electrostatic Latent Image Carrier 2 Counter Electrode 3 Heater 4 Heater 5 Waste Liquid Receiving 6 Waste Liquid Discharging Lid 7 Developer 8 Optical Semiconductor 9 Charge Wire 10 Exposure Section 11 Developing Roller 12 Heater 13 Controlling Member 14 Charge wire 15 Transfer paper

Claims (1)

[Claims] 1. Freezing point 30 to be solid at least at room temperature
80 ° C paraffins, waxes, low molecular weight polypropylene with a freezing point of 20-80 ° C, beef tallow with a freezing point of 20-50 ° C, freezing point of 30-
A developer in which a coloring material is dispersed in any of hardened oil at 80 ° C is heated to form a thin layer on a conductor in a molten state,
This thin layer is brought into contact with or brought close to an image bearing member having an electrostatic latent image, and due to the potential difference generated between the electrostatic latent image and the conductor,
An electrostatic latent image developing method characterized in that a visible image is formed on an image carrier by electrophoresing a coloring material.