JPS63138354A - Electrostatic recording body - Google Patents

Abstract

PURPOSE:To obtain a distinct image and to prevent the generation of drop-out of fine lines and abnormal discharging in a high-density electrostatic recording system by previously forming an electrostatic charge which has a polarity opposite to that of an impressed charge on the surface of a dielectric layer before applying the electrostatic charge for forming a recorded image. CONSTITUTION:In the titled body which is formed the dielectric layer contg. pigments usable to a spacer on a dielectric carrier the electrostatic charge having the polarity opposite to that of the impressed charge is previously formed on the surface of the dielectric layer, before, applying the electrostatic charge for forming the recording image. The polarity of the electrostatic charge which is previously applied on the surface of the dielectric layer mostly uses the negative polarity, as the discharging efficiency of the negative polarity is superior to that of the positive polarity in the present electrostatic recording system. Therefore, the polarity of the electrostatic charge which is previously applied, is desirable to be the positive polarity. Thus, even in case of using the high- density electrostatic charge recording system having 400 dots/inch, the distinct recorded image which does not generate the drop-out of fine lines and the abnormal discharging is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Graduation field of application) The present invention relates to improvements in electrostatic recording media, particularly electrostatic recording suitable for electrostatic facsimiles for high-density recording such as 400 dots/inch, electrostatic plotters, etc. It's about the body.

(Prior Art) In recent years, along with advances in communication technology, there has been increasing technical demand for electrostatic recording as a recording method that simultaneously satisfies high-speed recording and high image quality.

In particular, electrostatic printers are favorably used for optical communication and computer terminal devices such as facsimiles and printers, as well as CAD, which is a design technology using computers, and for recording output of these devices.

The multi-needle electrode recording method that is most commonly used in these electrostatic recording methods includes single-sided control type and double-sided control type.
In either case, the recording needle and the surface of the recording medium must face each other while maintaining a constant gap from the electrostatic recording medium. In the conventional recording with a recording density of 200 dots/inch, there was no particular problem in the generation of the discharge itself, probably because the area of the recording needle was sufficient.

However, in high-density recording such as 400 dots/inch, there is a close relationship between the smoothness of the surface of the dielectric layer and the image quality, and the distance to the recording needle must be kept within a certain appropriate range. Thin wires may be missing or abnormal discharge may occur.

The present inventors have attempted to improve the surface roughness of the dielectric layer, the number of irregularities, etc., while taking into account the resin forming the dielectric layer and its conductivity.
When a thin line is drawn, a normal discharge does not occur, and when a fine line is drawn, a phenomenon occurs, and conversely, depending on the location, the discharge reaches more than 10 times the area of the recording stylus, causing a so-called abnormal discharge that deteriorates the image quality. The current situation is that these problems remain unresolved.

(Problems to be Solved by the Invention) The present invention is an electrostatic recording medium used in a high-density electrostatic recording system such as 400 dots/inch, and is capable of producing clear images without thin line omissions or abnormal discharge. The purpose is to provide the body.

(Means for Solving the Problem) Since there is a limit to the degree of improvement in the above-mentioned problem when considering the structure of the recording medium, the present inventors further investigated the discharge and charging conditions on the surface of the dielectric layer. conducted research. Incidentally, it has been conventional common knowledge that the surface of the dielectric layer of an electrostatic recording medium must be free of static charge until an electrostatic charge for a recorded image is applied. At first glance, the present invention is an idea that goes against this common technical knowledge, but the inventors of the present invention have previously charged an electrostatic charge with a polarity opposite to that of the applied charge before applying an electrostatic charge for forming a recorded image. We have been conducting studies based on the idea that this may be a solution to the abnormal discharge.As a result, we have arrived at an invention consisting of the following configuration.

The present invention relates to an electrostatic recording material in which a dielectric layer containing a spacer pigment is formed on a conductive support. It is characterized by forming an electrostatic charge with a polarity opposite to that of the electric charge.

In the above structure, as a means of forming an electrostatic charge having a polarity opposite to the charge applied for recording images on the surface of the dielectric layer in advance, there is a method of placing an electrostatic charge using a corona charger, a method of placing an electrostatic charge on the surface of the dielectric layer, a method of placing an electrostatic charge using a corona charger, a method of placing an electrostatic charge on the surface of the dielectric layer in advance, a method of applying an electrostatic charge using a corona charger, a method of placing an electrostatic charge on the surface of the dielectric layer, and a method of placing an electrostatic charge using a corona charger, There are methods such as applying static charge with a needle electrode and charging the surface of the dielectric layer by friction. The state of static charge that is preformed on the surface of the dielectric layer is either to charge the entire surface, or to charge it uniformly or unevenly distributed in the form of islands. There are few problems when recording immediately after charging, but if a considerable amount of time elapses between charging the entire surface and recording, the charge will decay over time and the static charge will deteriorate. diameter is 3
They are distributed in the form of islands with irregular sizes, including those larger than 00μ. If the diameter of the electrostatic charge exceeds 300μ, this may improve the reproducibility of thin lines during recording, but on the other hand, abnormal discharge occurs between the recording needle and dots with an abnormal spread. This may result in deterioration of image quality. When static charges with such a huge diameter are generated, it is desirable to perform a static elimination process so that the diameter is within the range of 1 μm to 300 μm. As this static eliminating means, methods such as contacting with a metal roll, applying steam, and contacting with a static eliminating brush can be used.

Furthermore, instead of charging the entire surface, even when charging is done uniformly or non-uniformly in an island-like manner from the beginning, it is desirable to charge so that the diameter of each static charge is within the range of 1μ to 300μ. .

In order to form static charges with the above-mentioned diameter on the surface of the dielectric layer, it is good to apply them in the final step of the electrostatic recording medium manufacturing process, or for example, to form an electrostatic charge in a recording device for image formation. A method may be adopted in which the electrostatic charge application device is built in separately from the application device described above, and the electrostatic charge is applied immediately before recording.

The polarity of the electrostatic charge applied in advance to the surface of the dielectric layer can be either positive or negative depending on the recording method, but current electrostatic recording methods have a negative polarity discharge compared to a positive polarity discharge. Negative polarity is often used because of its good discharge efficiency, and therefore it is desirable that the electrostatic charge applied in advance be of positive polarity. Note that it is of course possible to confirm the distribution state of the electrostatic charge applied to the surface of the dielectric layer using an electron microscope.

Therefore, it is possible to form an electrostatic charge having a polarity opposite to that of the charge applied for forming a recorded image in advance on the surface of the dielectric layer.
It is suitable for electrostatic facsimile machines and electrostatic plotters for high-density recording such as 0 dots/inch, and is particularly effective in preventing thin lines when drawing thin lines. However, when recording by forming a positive electrostatic charge on the surface of the dielectric layer in advance and applying a negative polarity, the discharge starts faster than when recording without forming a positive electrostatic charge in advance. It is thought that more reliable discharge occurs probably because of the voltage drop.

Next, as a conductive support for forming the electrostatic recording medium, an inorganic salt such as sodium chloride, a cationic or anionic polymer electrolyte such as povinylbenzyltrimethylammonium chloride, a surfactant, or zinc oxide, Impregnated or coated with a conductive-treated metal oxide semiconductor such as zinc oxide, the surface resistivity is set to 10' to 10''87.
cm'' paper, plastic film, cloth, etc. are used.

For the dielectric layer constituting the electrostatic recording medium, an insulating resin such as an acrylic acid ester, butyral, or a mixture of methacrylic acid derivatives is used as the resin, and the spacer pigment contained in this is carbonate. Calcium, titanium oxide, amorphous silica, plastic pigments, etc. will be used.

Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to these Examples.

Example (Preparation of electrostatic recording material) A paint prepared by mixing calcium carbonate powder with an average particle size of 5 μm and methyl methacrylate resin at a ratio of 1:1 on a conductive-treated support was coated with a dry weight of 5 g/-. A dielectric layer was formed by applying the dielectric material as described above, and an electrostatic recording material was constructed.

Example 1゜The surface of the dielectric layer of the electrostatic recording medium prepared in advance was coated with VF'-520-TV type (16 pins/n) made by Matsushita Electric Transmission 0 Kiku.
) was installed with a recording head for electrostatic recording (simulator), with a pulse width of 50 μsec and a repetition rate of 20 msec, +300 μ to the pin electrode and -300 μ to the sub electrode were applied, and the recording speed was 5 Qtm. /sec
A positive electrostatic charge was formed.

When the potential on the surface of this dielectric layer is measured with a surface potentiometer, +
It was showing 40V. Further, when the charged state of the surface of the dielectric layer was observed using an electron microscope, circular dots with a diameter of 50 μm were confirmed.

After this electrostatic charge formation treatment, the electrostatic recording material was printed with a one-dot fine line using an electrostatic plotter EP-101 manufactured by Matsushita Electric Transmission Co., Ltd., and then developed. The resulting recording was good with no abnormal discharge or missing thin lines.

Example 2 Using a DC corona generator, a positive corona is generated under the condition of a corona voltage of 9 KV, and the above-mentioned electrostatic recording material prepared in advance is exposed to this corona generation, so that a positive electrode is formed on the entire surface of the dielectric layer. formed a static electrostatic charge.

When the potential on the surface of this dielectric layer is measured with a surface potentiometer, +
It was showing 30V. Furthermore, when the charging status of the surface of the electrostatic layer was observed using an electron microscope, it was confirmed that positive electrostatic charges were uniformly formed over the entire surface.

When the electrostatic recording medium subjected to the electrostatic charge formation treatment was subjected to recording using the same method as described in Example 1, the resulting recording was good without abnormal discharge or missing thin lines.

Comparative Example 1゜ On the surface of the dielectric layer of the electrostatic recording material prepared in advance,
When one-dot thin line recording was performed directly with an electrostatic plotter EP-101 manufactured by Matsushita Electric Transmission Co., Ltd. without performing the electrostatic charge formation process in advance as described in Examples 1 and 2, the recording did not show any thin line omissions. Many results were obtained.

Comparative Example 2 Using a DC corona generator, a negative corona is generated under the condition of a corona voltage of 9 KV, and by exposing the electrostatic recording material prepared in advance to this corona generation, a negative electrode is applied to the entire surface of the dielectric layer. formed a static electrostatic charge.

When the potential of the surface of this dielectric layer was measured with a surface potentiometer, it was found to be -40V. Furthermore, when the charging status of the surface of the dielectric layer was observed using an electron microscope, it was confirmed that negative electrostatic charges were uniformly formed over the entire surface.

When the electrostatic recording medium subjected to the electrostatic charge formation process was recorded in the same manner as described in Example 1, a recorded image was obtained although the entire surface became black, but the resulting recording did not have any missing fine lines. I got a lot of things.

(Effects) Even when the electrostatic recording medium according to the present invention is used in a high-density electrostatic recording system such as 400 dots/inch, it is possible to obtain clear recorded images without thin line omissions or abnormal discharge.

Claims (1)

[Claims] In an electrostatic recording medium in which a dielectric layer containing a spacer pigment is formed on a conductive support, before an electrostatic charge for forming a recorded image is applied, a charge opposite to the applied charge is applied to the surface of the dielectric layer. An electrostatic recording material characterized by forming polar electrostatic charges.