JPH04145451A - Carrier for developer - Google Patents

Abstract

PURPOSE:To perform printing without causing the adhesion of carrier to a paper by allowing the carrier whose saturation magnetization, particle size and specific gravity are set at specified set values to float while impressing a specified voltage between a photosensitive body and a rotor with a sleeve where a magnetic pole is arranged and attaching a carrier particle whose saturation magnetization, particle size and specific gravity are smaller than the specified set values to the photosensitive body and removing it. CONSTITUTION:The carrier 1 whose saturation magnetization, particle size and specific gravity are specified set values are allowed to float while impressing the specified voltage between the rotor with the sleeve 3 where the magnetic pole 2 is arranged and the rotatable photosensitive body 4 which is arranged to be opposed to the rotor 3. The carrier particle whose saturation magnetization, particle size and specific gravity are smaller than the specified set value of the carrier 1 which is allowed to float is attached to the photosensitive body 4 or the rotors with a magnet and the sleeve 5 and 6 respectively set near the rotor with sleeve 3 and the photosensitive body 4. Then, the rest is attached to the rotor with sleeve for recovery 7 which is set below the photosensitive body 4 and provided with the magnetic pole and recovered, thereby obtaining the carrier 1a for the developer used for the development of electrostatic photography.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carrier for a developer. [Prior Art] A two-component developer is used as a developer developed by applying the principle of electrostatic photography. is used.

[Problem to be solved by the invention]

The above-mentioned conventional magnetic two-component developer has the following characteristics.

As described in ρ382, co-authored by Nakamura and Amemiya, ``Recent electrophotographic process technology and equipment optimum design and application development software Giken, Management Development Center, published June 30, 1989, iron powder-based carriers are photosensitive. Journal of the Photographic Society 21, 1.14 (1982)
It has been raised by If carrier particles adhere to the photoreceptor during development, areas that should be properly printed may be chipped or
Problems such as missing characters may occur.

Measures taken on the equipment side include optimizing the magnetic pole arrangement in the magnet roll (Japanese Patent Publication No. 37-14798) and capturing scattered carrier particles with a magnet, but the latter method The mechanism becomes complicated, leading to an increase in the manufacturing cost of the device.

As a countermeasure from the carrier side, non-magnetic carrier such as slag that does not adhere to the magnet is removed to prevent carrier scattering in the initial printing stage immediately after developer is added. However, as the number of prints increases, carrier adhesion to the photoreceptor gradually progresses, and a new problem has appeared where about 0.1% of the carrier adheres to the photoreceptor based on the weight of the total developer carrier. became. As printing continued, a phenomenon was often observed in which the carrier stopped adhering to the photoreceptor. It has become necessary to improve the developer carrier so that the carrier does not adhere to the photoreceptor during continuous printing.

The present invention has been made in view of the above points, and an object of the present invention is to provide a carrier for a developer that can maintain the image quality of electrophotographic printing for a long time.

[Means to solve the problem]

The above purpose is to apply a predetermined voltage between a rotary body with a sleeve on which magnetic poles are arranged and a freely rotatable photoreceptor placed opposite to this rotary body, for developing a developer carrier used in electrostatic photography. While flowing the carrier whose saturation magnetization, particle size, and specific gravity are set to predetermined values, carrier particles with low saturation magnetization, small particle size, and small specific gravity, which are smaller than the predetermined set values of the flown carrier, are attached to the photoreceptor. The remaining rotating body with a collecting sleeve and a magnetic pole installed on the F side of the photoconductor is then attached to the rotating body with a sleeve and a magnet/sleeve installed near the photoconductor. This is achieved by attaching and recovering the material.

[Effect]

Since the above means is provided, carrier particles with low saturation magnetization, small particle size, and small specific gravity can be removed, and printing can be performed without inducing carrier adhesion to paper.

〔Example〕

The present invention will be described below based on five illustrated embodiments. FIG. 1 shows an embodiment of the invention. In this embodiment, one developer carrier 1a used for electrostatic photographic development is placed between a rotary body 3 with a sleeve on which a magnetic pole 2 is arranged and a rotatable photoreceptor 4 disposed opposite to this rotary body 3. A carrier 1 with saturation magnetization, particle size, and specific gravity set to predetermined values is flowed while applying a predetermined voltage. The carrier particles are attached to the photoreceptor 4, and the sleeved rotating body 3. The remaining parts were attached to the rotating bodies 5 and 6 with magnets and sleeves installed near the photoreceptors 4, respectively.
The particles were attached to and collected on a rotating body 7 with a collection sleeve equipped with magnetic poles, which was installed below the photoreceptor 4. By doing this, carrier particles with low saturation magnetization, small particle size, and low specific gravity can be removed, making it possible to print without inducing carrier adhesion to paper, and improving the image quality of electrophotographic printing. Developer carrier 1 that can last for a long time
You can get a.

In addition, in the figure, 8 is a supply tray, 9 is a collection tray,
10 is a doctor.

An example implemented using the figure will be described below.

As Example A, the average particle size is 110 μm and the specific gravity is 5.1.
, 2 kg of spherical carrier particles (EX-1) having a set value of saturation magnetization of 10,100 e/g in a magnetic field of 1,000 Nieslrad and containing iron oxide as a component were supplied to the supply tray 8. Using a rotary body 3 with a sleeve having a diameter of 60 gauss and equipped with a magnet 2 exhibiting a magnetic flux density of about 700 Gauss on the sleeve, the carrier 1 in the supply tray 8 is conveyed near the surface of the photoreceptor 4 while the sleeve is being conveyed. The attached rotating body 3 was grounded, and a voltage of -400 V was applied to the surface of the photoreceptor 4. The distance between the rotary member 3 with a sleeve and the photoreceptor 4 was maintained at 1.2 cm. In this state, the rotating body 3 with sleeve is rotated at 150 rotations per minute, and the photoconductor 4 is rotated at 150 rotations per minute.
was rotated at a speed of 100 revolutions for 50 hours. The carrier attached to the magnet of the magnet installed near the photoreceptor 4 and the rotating body 3 with a sleeve and the rotating body 5 with a sleeve is O-6g (0,
03%), the average particle size is 79 μm, the specific gravity is 3.7,
The saturation magnetization was 25 emu/g.6 The carrier attached to the magnet of the rotating body 6 with a magnet/sleeve installed near the surface of the photoreceptor 4 was Ig (0.05%),
Average particle size is 80 μm, specific gravity is 3.6, and saturation magnetization is 33.
emu/g. A developer containing a combination of carrier collected by a magnet installed on a rotating body 7 with a collection sleeve and styrene-acrylic toner was printed on A4 size paper at a speed of 60 pages per minute. The photoreceptor of this electrostatic printing machine is an organic photoconductor, and the toner is page-chargeable. Table 1 shows the results of extracting the printed matter and visualizing the image. As shown in Example A in the same table, there were no omissions or omissions up to 300,000 pages, and there was no carrier adhesion to the paper. Ta. According to this embodiment, carriers with low saturation magnetization can be selectively removed from the carrier particles, so printing can be continued up to 400,000 pages without causing omissions, omissions, or carrier adhesion to the paper. can do.

As a comparative example A'' of this example A, the same operations as in Example A were carried out except that the processing performed on the carrier EX-1 was not carried out. As shown in Figure 2, omitted characters, missing parts, and carrier adhesion were observed.

The voltage of the rotating body 4 shown in Example A of Table 1 is shown in Table 1 as a comparative example. , missing parts and carrier adhesion were observed.

Instead of the carrier EX-1 used in Example A, the average rough diameter was 60 μm, the specific gravity was 4.9, and the set value of saturation magnetization was 10.
A sample was prepared using the same procedure as in Example A, except that spherical carrier particles having iron oxide as a component were used and exhibited a value of 6° em u/H in a magnetic field of 0.00 Oersted. The amount of carrier attached to the rotating body 5 with magnet and sleeve is 0.8 g (0.04%), and the average particle size is 46 μm.
, specific gravity is 3.6. The saturation magnetization is L 5 e m u /
It was g. The carrier attached to the rotating body 6 with magnet and sleeve weighs 1-2 g (0.06%) and has an average particle size of 45
μm, specific gravity was 3.5, and saturation magnetization was 20 emu/g. Up to 64 million pages were printed, but no omissions, omissions, or carrier adhesion were observed (no indication was made).

Instead of the carrier EX-1 used in Example A, the average particle size was 250 μm, the specific gravity was 7.8, and the set value of saturation magnetization was 1.
200 em u / in a magnetic field of 000 oersted
g, and spherical carrier particles containing iron as a component were used. The distance between the rotating body 3 with sleeve and the photoreceptor 4 is set to 2.
Example C was obtained by carrying out the same operation as in Example A, except that the length was maintained at 4 m. The carrier attached to the rotating body 5 with magnet and sleeve weighs 0.2 g (0.01%), has an average particle size of 135 μm, and has a specific gravity of 7.0. Saturation magnetization is 50e m
It was u/g. The carrier attached to the rotating body 6 with magnet/sleeve weighs 0.4 g (0.02%), has an average particle size of 135 μm, a specific gravity of 5.5, and a saturation magnetization of '70.
emu/g. In 200,000 pages, there were 3 omissions and only 2 carrier adhesion (not shown).

Example 1 except that a mixture (developer) consisting of 1 part by weight of styrene-acrylic toner with an average particle size of 11 μm and 100 parts by weight of EX-1 was used in place of the carrier EX-1 used in Example A. Example 2 was obtained by performing the same operations as in A. The amount of carrier attached to the rotating body 5 with magnet and sleeve is 0.5 g (0,025%), and the average particle size is 75
μm, specific gravity is 3.6. The saturation magnetization is 23 em u /
It was g. The amount of carrier attached to the rotating body 6 with magnet and sleeve is 1.0 g (0.05%), the average particle size is 73 μm, the specific gravity is 3.7, and the saturation magnetization is 30 e mu
/g. The printed result was 150,000 pages with 2 omissions.
However, the amount of carrier adhesion was as small as 1 (not shown).

Example E was prepared by repeating the operations performed in Example A to remove carrier particles with low saturation magnetization, and then coating the carrier with 0.5 weight percent of an acrylic polymer.

Printing continued using this polymer coated carrier in the same manner as in Example A. As a result of printing 50% of the pages, no omitted characters or missing parts were observed, and there were only two carriers attached to the paper (not shown).

In these Examples and Comparative Examples, the particle size, specific gravity, and saturation magnetization were measured in the following manner.

The specific gravity was calculated based on the values before and after placing about 0.1 g of carrier particles in a vicinometer (a type of glass weighing bottle), injecting water, and measuring the weight at 25°C.

The particle size was determined by measuring the particle size of about 30 spherical carrier particles under an electron microscope and calculating the average value.

Saturation magnetization was measured by accurately weighing a certain amount of carrier particles (about 0.1 g), placing them in a measurement cell, and applying a certain magnetic field.

〔Effect of the invention〕

As described above, the present invention makes it possible to maintain the image quality of electrophotographic printing for a long time, thereby providing a developing carrier that makes it possible to maintain the image quality of electrophotographic printing for a long time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an apparatus for removing a weakly magnetic carrier according to an embodiment of the developing carrier of the present invention. 1 is a carrier (predetermined setting value), 1a is a carrier, 2 is a magnetic pole, 3 is a rotating body with a sleeve, 4 is a photoreceptor, 5.6 is a rotating body with a magnet/sleeve, and 7 is a rotating body with a recovery sleeve. Name of patent applicant: Hitachi Koki Co., Ltd. (v++7 (ya ff 71'l n kabura 1, value) pointed rear me L no honchin h-half 'IK IJ transformation

Claims (1)

[Scope of Claims] 1. A developer carrier used for electrostatic photographic development, wherein the carrier comprises a rotating body with a sleeve on which magnetic poles are arranged, and a rotatable photoreceptor disposed opposite to this rotating body. A carrier with saturation magnetization, particle size, and specific gravity set to predetermined values is flowed while applying a predetermined voltage between the two, and the flowed carrier has a low saturation magnetization, small particle size, and small specific gravity that are smaller than the predetermined set values. The carrier particles are attached to the photoconductor, and the magnetic poles are installed below the remaining photoconductor, and the magnetic poles are attached to the rotary body with a sleeve and the magnet/rotator with a sleeve installed near the photoconductor, respectively. A carrier for developer, characterized in that the carrier is collected by adhering to a rotating body with an attached collection sleeve. 2. The developer carrier according to claim 1, wherein the carrier particles have a saturation magnetization of less than 1/4 of a set value of saturation magnetization. 3. The small diameter carrier particles are 70% of the particle diameter setting value.
2. The developing carrier according to claim 1, wherein the developing carrier is less than or equal to: 4. The low specific gravity carrier particles have a specific gravity of 70% of the set value.
2. The developer carrier according to claim 1, wherein the developer carrier is less than or equal to: 5. The developer carrier according to claim 1, wherein the developer carrier is magnetic and is an iron oxide or a powder containing iron as a component. 6. The developer carrier has a diameter of 30 to 300 μm.
The developer carrier according to claim 1.