JPS60173557A - Pressure-fixable magnetic toner for reversal development - Google Patents

Abstract

PURPOSE:To obtain a high-quality image stably by specifying a triboelectrification amt. and voltage generated by rotation of the toner particles on a nonmagnetic sleeve provided with a permanent magnets in the inside. CONSTITUTION:Electrostatic charge amt. measured by the blowoff method needs to be in the range of -1--10muC/g. A good image can be obtained by using a toner having a surface potential of -5--20V when the measuring device in which the outside diameter of a nonmagnetic sleeve 1 is 50mm.phi, that of permanent magnets 12 is 46mm.phi, its length is 150mm., a magnetic flux density of 1,000G on the sleeve 1 synmetrically magnetized with 12 poles is used, the gap g between the sleeve 1 and an electrometer 3 is adjusted to 5mm., 3g of toner is fed, and the magnets 2 are rotated at 1,000r.p.m.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pressure fixing magnetic toner used in so-called reversal development, in which toner is attached to non-image areas of an electrostatic charge pattern formed on an electrophotographic photoreceptor. Regarding.

Prior Art In recent years, with the spread of computer computers, they have been used as peripheral terminal devices to output information in the form of characters and graphics and create hard copies.
Printer development is progressing.

Conventionally, the mainstream of printers has been impact printers in which selected characters collide with paper via an ink ribbon to print. However, the increasing performance of computers and the diversification of information processing have enabled rapid processing of large amounts of information and the ability to
A variety of output formats are required, such as graphics and letters of arbitrary size, and it is difficult to meet these demands with conventional impact printers, so a new non-impact printer (
electronic printers) were developed. Non-impact printers are classified into electrophotographic, electrostatic, and inkjet printers in terms of recording method, but electrophotography is the most popular in order to meet the recent demands for faster and higher density recording. It's advantageous.

The recording principle of printers using electrophotography is essentially the same as that of general copying machines, and is based on uniform charging of the recording material,
Basics of forming an electrostatic latent image by light exposure, developing the electrostatic latent image, and electrostatic transfer of the developed 1 to toner images onto plain paper■
It consists of steps. However, in printers, information from a computer is generally written on a uniformly charged recording medium using a laser beam, etc., and the laser beam writing area, that is, the exposed area, is developed. need to be developed.

As a dry developer that can be applied to the reversal development method, a two-component developer consisting of carrier particles and toner that is used in a magnetic brush development method or a cascade visual imaging method has been known. Generally, the above developer is used.

In a two-component developer, a toner made of a natural or synthetic resin containing a colorant such as carbon black is mixed with carrier particles such as iron powder or glass beads, and the two are triboelectrically charged. A frictional charge having the same polarity as the charge of the electrostatic latent image is obtained, and only the toner adheres to the non-image area of the electrostatic latent image on the recording medium, and development is performed. In this method, since the toner has a clear electrostatic charge, it is possible to faithfully develop the non-image area of the electrostatic latent image on the recording medium.

Furthermore, since the electrostatic charge of the toner is retained even after development, it is possible to electrostatically transfer the toner image to general-purpose plain paper by corona charging with the opposite polarity, and a high-quality printer image can be obtained.

However, in order to achieve good frictional electrification of carrier particles and toner, it is necessary to use them in a certain proportion, which requires a monitoring device, which complicates the printer apparatus. In addition, since the carrier particles are mixed and stirred with the toner for a long time, it is necessary to
- A film of the toner, so-called spent, is formed, and the triboelectric charging properties between the toner and the carrier are reduced.

Therefore, there is a drawback that the developer that has reached the end of its spent life must be disposed of.

In order to improve these drawbacks, a method has been devised in which development is performed by bringing only toner particles close to or in contact with the surface of a recording medium without using carrier particles. This involves incorporating fine ferromagnetic particles into the toner, making the toner itself possess magnetism that is sensitive to magnetic force, eliminating the need for conventional carrier particles, and simplifying the developing mechanism, allowing electrophotographic devices to be made more compact. Because of its advantages, this method was first put to practical use in popular copying machines that perform regular images.

Toner containing these ferromagnetic fine particles, so-called magnetic toner, is classified into conductive magnetic toner and insulating magnetic toner depending on the range of electrical resistance of the toner. The former has an electrical resistance in the range of 10 8 to 10 13 Ω·cm, and the latter has an electrical resistance of 1Q130·cm or more.

In order to apply these magnetic toners to printers, it is necessary to improve them so that they can be applied to reversal development, and several attempts have been made to do so. In addition, in terms of method, JP-A-55-1. ．． As disclosed in Japanese Patent No. 34864, a method has been proposed in which a DC bias voltage having the same polarity as the electrostatic latent image on a recording medium is applied to a conductive sleeve of a developing device to perform development.

This method is particularly effective in the case of conductive magnetic toner, and the toner charged with the same polarity as the electrostatic latent image on the recording medium by the bias voltage will generate electrostatic charges in the non-image area of the electrostatic latent image on the recording medium. The film adheres to the surface and undergoes reversal development. However, due to the high conductivity of toner, when the toner image after development is electrostatically transferred onto other substrates such as paper, the transferred image is disturbed. To prevent this, special resistance treatment is required. Treated paper is required.

On the other hand, if the conventional insulating magnetic toner for regular development is applied as is to the reversal development method in which a bias is applied, 1
~Since the electrical resistance of the toner is high, the toner can be electrostatically transferred to plain paper with low electrical resistance. However, with conventional insulating magnetic toners, the electrical insulation of the toner is insufficient, and the amount of triboelectric charge of the toner is insufficient, resulting in a decrease in image density and fogging when applied to the reversal development method. The drawback was that only a large number of images could be obtained.

In addition, in printers using electrophotography, a pressure fixing method is often adopted from the viewpoint of power saving and quick start, and there is a desire to develop insulating magnetic toner to which pressure fixing can be applied. The reality is that a magnetic toner of high quality and good fixing properties has not been obtained.

OBJECTS OF THE INVENTION An object of the present invention is to provide a pressure fixing type magnetic toner for image use that eliminates the above-mentioned drawbacks and can stably obtain high-quality images. .

Structure and Function of the Invention The structure of the present invention is to provide a pressure fixing type magnetic toner for reversal development which is mainly composed of a resin containing a wax-like compound and magnetic powder, and which has a triboelectric charge amount of -1 to -10μ by the blow-off method.
c/lr, and the voltage generated by the rotation of toner particles on a non-magnetic sleeve having a permanent magnet member therein is in the range of -5 to -20V.

In order to perform a good reversal phenomenon, it is necessary for the toner to have an appropriate amount of triboelectric charge. It was considered good.

However, even if the toner charge amount is within this range,
It was not always possible to obtain high-quality images, and there were variations in image quality. The amount of charge was measured using a commercially available blow-off powder charge amount measuring device (TB-200 manufactured by Toshiba Chemical).
This is a value measured by the following procedure, and the same applies below. .

First, carrier (Nippon Iron Powder Z200) '10 (1) and toner 0.5 (+) were placed in a plastic container with an outer diameter of 40 mm, and the container was rotated for 10 minutes using a flow surface angle measuring device. Weigh out 200 m (l) of the mixture and put it into a designated container using a 325 mesh sieve.
The amount of charge was measured under the conditions of cn+' and a blow time of 4 Qsec for one hour.

As a result of various studies, the inventors of the present invention and others have found that by measuring the amount of triboelectric charge of toner under conditions corresponding to actual development and appropriately controlling the amount of charge at this time, images of constant quality can always be obtained. I found that I could get it. The details are as follows.

Here, FIG. 1 is a sectional view of the toner potential measuring device.

In the figure, 1 is a non-magnetic sleeve, 2 is a permanent magnet member, and 3 is a surface electrometer.

The present inventors have determined that the non-magnetic sleeve 1 has an outer diameter of 5Qvnφ, the permanent magnet member 2 has an outer diameter of 46mmφ, a length of 150mm, and a length of 12mm.
The above measuring device with polar symmetrical magnetization and magnetic flux density on the sleeve of 1000G measures the non-magnetic sleeve 1 and the electrometer (Trek 3).
44) The distance 9 between the sleeve 1 and the sleeve 1 was adjusted to 5 nm, 3 g of toner was supplied onto the non-magnetic sleeve 1, and the surface potential of the toner was measured when the permanent magnet member 2 was rotated at 100 Or, plm.

When we looked at the correlation between the surface potential at this time (when the potential was in a constant state) and the image quality, we found that the surface potential was 75 to -2
It has been found that good images can be obtained within the range of 0V. In other words, the surface potential measured in this way is generated by friction between the toner itself and between the toner and the non-magnetic sleeve when the non-magnetic sleeve is transported while rotating, and is the result of the friction between the toner and the non-magnetic sleeve, which is the cause of the actual development. Since the charging mechanism of Togi toner is quite similar, it is thought that it corresponds well to the actual image.

In addition, in the present invention, in order to perform good reversal development and electrostatic transfer to plain paper with low electrical resistance (1012 Ω CI or less), the electrical resistance of the toner is set to 1013 Ω CI.
It is also necessary to make it more than am.

The resistivity was measured by weighing out an appropriate amount (10 9-mu) of magnetic toner and using an improved dial gauge with an inner diameter of 3.05.
It is inserted into a Teflon (trade name) insulating cylinder of n+mφ (cross-sectional area = 0.073cm), and the electrical resistance of the 1-ner is measured under a load of 0.1kc+ in an electric field of DC4000V-cn+. lock out rates. For the measurement, a 4329 type insulation resistance manufactured by Hewlett Packard Card was used.

As the material for the toner of the present invention, various materials used in ordinary magnetic toners can be used. That is, the ferromagnetic fine particles include substances that are extremely strongly magnetized in the direction of a magnetic field, such as ferrite.

Alloys or compounds containing ferromagnetic elements such as magnetite, iron, cobalt, and nickel, as well as various alloys that exhibit ferromagnetism through some kind of treatment such as geothermal treatment, can also be effectively used. These ferromagnetic materials are contained in the toner, so the average particle size is 0.1.
A thickness of approximately 3 μm is desirable. The amount contained in the toner is preferably 60 to 80% by weight based on the total weight of the toner. When the amount is less than 35% by weight, the magnetic force of the toner is 1
0- decreases, toner comes off from the developing magnet roll, and the image becomes distorted. Furthermore, the fluidity of the toner also decreases. If it exceeds 55% by weight, the resistivity of the toner tends to decrease because the ferromagnetic fine particles themselves generally have conductivity, resulting in poor developability and transferability and image disturbance. Therefore, even if a relatively large amount of ferromagnetic material is added within the scope of the present invention, for example, when adding 75% by weight or more, the surface of the ferromagnetic material must be coated with resin or high-grade material in advance in order not to reduce the electrical insulation properties of the toner. It is desirable to coat with fatty acids, higher fatty acid esters, fluorine-modified silicone oils, various silicone oils, organometallic compounds, etc.

The toner of the present invention may use, for example, the following pressure-sensitive resin in order to enable pressure fixing properties. Higher fatty acids, higher fatty acid metal salts.

Higher fatty acid derivatives, high-grade Ih acid amides, waxes, rosin derivatives, alkyd resins, epoxy-modified phenolic resins, natural resin-modified phenolic resins, amino resins,
Silicone resin, polyurethane.

Area resin, polyester resin, acrylic acid or methacrylic acid and long chain alkyl methacrylate.

Copolymerized oligomer with long-chain alkyl acrylate.

Copolymerized oligomers of styrene and long-chain alkyl acrylates and long-chain alkyl methacrylates, polyolefins,
Examples include ethylene vinyl acetate copolymer, ethylene rubinyl alkyl ether copolymer, maleic anhydride copolymer 1, petroleum residue, and rubbers.

These resins can be arbitrarily selected and mixed as desired, but in order not to reduce the fluidity when used as a toner, resins with a glass transition point exceeding 40°C or resin mixtures are effective. used. The amount of fixing resin contained in the toner is 1 ferromagnetic fine particles, 1 color adjusting pigment,
Although the proportion excludes dyes and charge control agents, it is necessary to add at least 20% by weight of the total amount of the toner in order not to reduce the fixing properties of the toner. - As the color-adjusting pigment and dye, any of the various pigments used in general dry developers can be used. However, the content relative to the total amount of the toner needs to be within a range that does not reduce the electrical properties of the toner. In the present invention, the amount of these additions is 10% based on the total amount of toner.
Less than % of the weight is appropriate. Pigments and dyes that can be used include, for example, carbon black, nigrosine dye, aniline blue, Chikara Oil Bray, chrome yellow, ultramarine blue, DuPont Oil Red,
Quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal and mixtures thereof are used. If the ferromagnetic fine particles themselves are colored and there is no need to add these color modifiers, there is no need to add them to the toner. Furthermore, when carbon black is used, since carbon black is a conductive particle and does not reduce the electrical insulation properties of the toner, it should be used in an amount of 0.5 to 1 part by weight per 100 parts by weight of the resin component of the toner. need to be added. Further, since carbon black has various properties depending on its manufacturing method, it may itself have charge control properties, and this can be effectively utilized.

The above pigments and dyes are used in combination with ferromagnetic fine particles and fixing resin for the purpose of controlling frictional electrification between the sleeve surface of the toner developing magnetic roll and the recording medium surface.
Specific pigments and dyes can be selected and used. However, in order to control the charge of the toner, conventionally known dyes or pigments can be added as charge control agents. For example, nigrosine dye, which has positive triboelectric properties,
Other examples include nigrosine dyes modified with higher fatty acids and metal-containing (Cr) azo dyes having negative triboelectric charging properties. Also, Special Publication No. 51-28232, Special Publication No. 53-1
As described in Publication No. 3284@, etc., certain types of polymer dyes have more stable charges than the above-mentioned dyes, and are particularly effectively used in magnetic 1 to 1-toner dyes. Furthermore, oxidized carbon black and resins having positive or negative charge control groups can be regarded as a type of charge control agent and can be effectively used.

Toner made of the above-mentioned material 1 composition is prepared by pre-mixing the raw materials with a mixer such as a ball mill or super mixer, heating and kneading with a kneading machine such as a kneader, cooling, assimilating, and pulverizing.
Then, it is obtained by classification and heat treatment. The heat-treated toner particles can be used by adding and mixing various commonly used toner additives. This is added for the purpose of adjusting the electrical insulation properties and fluidity of the toner.
Even with the addition of additives, it is necessary to ensure that the electrical properties of the toner remain within the scope of the present invention. Various inorganic and organic substances can be used as additives, but those with an average particle size of 0.01 to 5.
00 μm, and it is desirable to have an effect within the range of 0.01 to 4% by weight based on the total amount of the toner. If additives outside the above range are added, the electrical insulation properties of the toner will generally be out of the range of the present invention, and good developed and transferred images will not be obtained. Examples of additives that can achieve the present invention include:
Examples include silica powder such as Erosil, carbon black, various dyes, pigments, and fine resin powder such as finely powdered polytetrafluoroethylene and polystyrene.

The magnetic toner of the present invention is attached to a conductive sleeve covering a developing magnet roll to form a magnetic brush, and is triboelectrically charged by relatively rotating the magnet roll or sleeve. When a DC bias voltage having the same polarity as the latent image is applied, the non-image portion of the electrostatic latent image on the recording medium can be developed satisfactorily. Further, since the toner image after development has an electric charge, by stacking the transfer sheets and applying an electric field, the toner image can be successfully transferred to the transfer paper. With the magnetic toner of the present invention, particularly excellent reversal images can be obtained by the developing method described below. However, the developing method is not limited to the following method.

FIG. 2 is an explanatory diagram showing an embodiment of a preferred reversal vision method for magnetic toner of the present invention. In the same figure, 4 is
A recording medium holding an electrostatic latent image, the conductive support 4 of the recording medium
a is rotated at a constant speed in the direction of the arrow. Reference numeral 5 denotes a cylindrical conductive sleeve for carrying and conveying magnetic toner, which in the present invention rotates in the direction of the arrow at a peripheral speed faster than the drum. As the sleeve 5 rotates, the magnetic toner 7 is conveyed to the developing section while being charged by frictional electrification. 6
is a container containing insulating magnetic toner 7, and is designed to bring the contained toner into contact with the surface of sleeve 5. Reference numeral 8 denotes a magnetic blade, which is arranged at a small distance from the sleeve 5.

This distance is 0.2 to 0.5 m in the magnetic toner of the present invention.
A range of m is appropriate. The amount of toner moving on the sleeve 5 is regulated by the magnetic blade 8. Reference numeral 9 denotes a permanent magnet member consisting of a multi-pole (six poles in the figure) magnet roll, which is fixed so as not to rotate once in the example shown in the figure. In order to perform reversal development, a DC bias voltage is applied to the conductive sleeve 5 by a power source 10 so that the sleeve side has the same polarity as the electrostatic latent image on the recording medium 4 in the developing section. The distance between the surface of the recording medium 4 and the sleeve 5 in the image area is set to be slightly wider than the distance between the sleeve 5 and the magnetic blade 8 in order to prevent fogging. In the magnetic toner of the present invention, this distance is suitably in the range of 17-0.25 to 0.5II1 m.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the content of the present invention is not limited by these specific examples.

Example 1 Polyethylene wax (L E L -80 manufactured by Sanyo Chemical Co., Ltd.
0) 26 heavy stones, carbon black (Mitsubishi Kasei MA-
600) 1 weight, 1 part, magnetite (MAT- manufactured by Toda Kogyo)
220) 72 parts by weight were dry premixed for 5 minutes using a super mixer, and then heated and kneaded using a kneader. After cooling and solidifying, it was coarsely pulverized with a hammer mill and further finely pulverized with a jet mill. The obtained crushed powder was classified into 5 to 20 μm, and then 8
0.17 parts by weight of the same carbon black as above was added to the obtained toner particles, which were introduced into a hot air stream at 0°C and subjected to heat treatment, and passed through a hot air stream at 80°C to form a magnetic toner (sample 1). adjusted.

When the electrical properties of the above toner are measured by the above method,
The volume resistance was 2×10”Ω·CI, the blow-off charge amount was -5.3 μC/(], and the charging potential was -18-12V.

This toner was adhered to a magnet-fixed-sleeve rotary developing device, and images were evaluated based on reversal development. The developing device shown in FIG. 2 has a sleeve diameter of 32 mm, a number of magnetic poles of 6, a sleeve surface magnetic flux density of 1000 G, a doctor blade made of magnetic 5US430, and a distance from the sleeve surface of 0.2111111 teeth. The distance between this developer and the sleeve surface is 0.2+nm. The distance between the sleeve surface and the photoreceptor drum surface is 0.25 mm.
The photoreceptor was developed by attaching the sleeve to a modified commercial copying machine (5C120 manufactured by Copia Corporation) at 300 revolutions per minute and rotating the photoreceptor drum in the same direction at a speed of 24 revolutions per minute. The photoreceptor has an outer diameter of 120 mm and is sensitized with tellurium.
Using a mmφ selenium drum, the drum was charged to +600 V, and a DC bias voltage of +400 V was applied to the sleeve side to perform reversal development. The light source is a semiconductor laser (
Hitachi 11L-1400, oscillation wavelength 807 mm
, output 3mW), and the laser beam is
FF, ON' at the printed part? The character pattern was divided into parts and exposed to light. After the drum visual image, a plain paper having a volume resistivity of 10120 cm or less in terms of resistivity was used as a transfer sheet, and toner was electrostatically transferred at a transfer voltage of -4.5 KV to produce a magnetic toner transfer image. This transferred image is
It was passed between pressure rolls (steel rolls whose surfaces were plated with hard chrome) adjusted to a linear pressure of ko/am and fixed at room temperature. As a result, a good image with an image density of 1.15 and no blur or dust was obtained.

Example 2 0.7 parts by weight and 0.5 parts by weight of carbon black were added to the toner particles of Example 1, respectively.

Sample No. 0.3 parts by weight, 0.2 parts by weight, 0.1 parts by weight
, 2. No, 3. No, 4. No, 5. No. 6 was prepared in the same manner as in Example 1. The electrical properties and image evaluation results (under the same conditions as in Example 1) of these magnetic toners are shown in Table 1, and it is clear that clear printer images with high image density can be obtained.

Table 1 The amounts of carbon black added to the toner particles of Example 1 were 0 parts by weight (no addition), 0.02 parts by weight, and 0.02 parts by weight, respectively.
Sample No. 05 parts by weight, 1.0 parts by weight, 7~No.
No. 10 was prepared in the same manner as in Example 1.

The electrical properties and image evaluation results of these magnetic toners are as follows:
As shown in Table 2.

Table 2 21 - Effects of the Invention As described above, the present invention can provide a pressure-fixed magnetic toner for reversal development that can stably obtain high-quality images. This invention can be said to have excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a toner potential measuring device, and FIG. 2 is a sectional view of a developing device showing an embodiment of the pressure fixing type magnetic toner for reverse vision images according to the present invention. 1.5... Sleeve, 2.9... Permanent magnet member, 3
...Surface electrometer, 4...Recording body, 7...Magnetic toner, 8...Magnetic blade. Patent applicant Hitachi Metals Co., Ltd. 22-

Claims (1)

[Claims] A pressure-fixed magnetic toner for reversal development whose main components are a resin containing a wax-like compound and magnetic powder has a triboelectric charge amount in the range of -1 to -10 μO/Cl by the blow-off method, and has a permanent magnetic member inside. The voltage generated by the rotation of toner particles on a non-magnetic sleeve with -5 to -20
Pressure fixing type magnetic toner for reversal development characterized by being in the range of V 〇