JPH05134426A - Electrostatic information recording medium - Google Patents

Abstract

PURPOSE:To obtain an electrostatic recording medium excellent in charge holding characteristics even for positive charge, and excellent in heat resistance, moisture resistance and workability. CONSTITUTION:This electrostatic recording medium has a charge holding layer 11 at least on an electrode layer 13. The charge holding layer 11 consists of a polystyrene resin having 10<3>-10<6> mol.wt. with addition of an insulating org. matter having no photoconductivity. Thereby, the obtd. medium has excellent heat resistance, low water absorptivity, and excellent formability. Since this medium is excellent in holding performance of positive charges, it is useful as an electrostatic information recording medium to be used in combination with an org. photosensitive material having the discharge characteristics of positive charges. The means to accumulate information is an electrostatic unit, so that the accumulated information has high quality and high resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic information recording medium capable of electrostatically recording information by an exposure method at the time of applying a voltage and reproducing the information at an arbitrary time, and particularly when the information charge is a positive charge. Also has excellent charge retention characteristics,
The present invention also relates to an electrostatic information recording medium having excellent heat resistance and moisture resistance and excellent workability.

[0002] Conventionally, in electrophotography or the like, a photoconductive layer is vapor-deposited on an electrode layer, the entire surface of the photoconductive layer is electrically charged, and then imagewise exposure is performed to leak the electric charge in the exposed portion, thereby exposing the photoconductive layer on the photoconductive layer. It is known that an electrostatic latent image is optically formed, a toner having an electric charge having a polarity opposite to that of the residual electric charge is attached, electrostatically transferred to a paper or the like, and developed. This is mainly used for copying, but the period for holding the electrostatic charge in the photoconductive layer as a recording medium is shortened and toner development is performed immediately after the electrostatic latent image is formed. Then it is too unusable due to its low sensitivity.

On the other hand, in an electrostatic information recording medium which is disposed so as to face a photoconductor having a photoconductive layer on the electrodes, image exposure is performed with a voltage applied between the electrodes. An electrostatic information recording method has been developed which uses an exposure under voltage application to record an electrostatic charge image of extremely high resolution on an electrostatic information recording medium. In the electrostatic information recording medium used in this electrostatic information recording method, its charge retention property is extremely important. Although the polystyrene resin generally has low charge retention characteristics, it cannot be used as an insulating material that can be used as an electrostatic information recording medium because of its high glass transition temperature and low hygroscopicity.

[0004]

The present inventors have previously filed an application for an electrostatic information recording medium having a polystyrene resin as a charge retention layer, but the present invention aims to improve the information recording medium. The purpose is to improve the charge retention performance in the case of.

[0005]

The electrostatic information recording medium of the present invention is an electrostatic information recording medium in which a charge retaining layer is laminated on at least an electrode layer, and the charge retaining layer has a molecular weight of 10 ³ to 1 1.
Characterized in that it is obtained by adding an insulating organic material having no photoconductive 0 ⁶ polystyrene resin in.

FIGS. 1A and 1B are cross-sectional views showing an example of each aspect of the electrostatic information recording medium. In the figure, 11 is a charge retention layer, 13 is an electrode, and 15 is a support. ..

As a polystyrene resin, the specific resistance is usually 1
A resin having an insulating property of about 0 ¹⁶ Ω · cm and a molecular weight of 10 ³ to 10 ⁶ is used. If the molecular weight is less than 10 ³ or exceeds 10 ⁶ , problems of coating suitability and film stability occur.

Examples of such a polystyrene resin include Picolastic D125, A75, D75, D125, D137, D manufactured by Rika Hercules Co., Ltd.
150 or the like can be used.

Next, the organic substance added to the polystyrene resin does not exhibit photoconductivity and has a specific resistance of 10 ¹⁴ Ω.
・ It is necessary to have insulation of more than cm. Further, it is preferable that the boiling point is equal to or higher than the heat treatment temperature so as not to evaporate in the drying step when manufacturing the electrostatic information recording medium.

Examples of the solvent for the polystyrene resin include xylene, toluene, monochlorobenzene, methyl ethyl ketone, chloroform, benzene and tetrahydrofuran.

The organic substance in the present invention is not particularly limited as long as it meets the above-mentioned conditions. For example, benzene having at least one selected from an amino group, a nitro group and a halogen group as a substituent, Naphthalenes, cyclohexanes having a halogen group as a substituent, polymers such as polymethacrylic acid, and photosensitizers 2,4,7-trinitrofluorenone, 7,7,8,
8-tetracyanoquinodimethane, phenothiazine, perylene, phthalic anhydride, maleic anhydride, fluoranil,
Examples thereof include triphenylamine, and the polystyrene resin may be contained in an amount of 10 ⁻³ wt% to 1 wt%.

As a method of applying the polystyrene resin solution to which the organic substance is added onto the electrode layer, spinner coating, spraying method, brush coating method, dipping method and the like can be applied. The solvent is evaporated to remove at a temperature, and after drying, the film thickness is 0.1 μm to 100 μm.
m, preferably 0.1 μm to 5 μm. If the film thickness is 0.1 μm or less, charge leakage occurs even if the charge is retained, and if it is 100 μm or more, the flexibility is lost when the information recording medium needs flexibility.

After forming a polystyrene resin solution containing an organic substance into a film and adhering it to an electrode with an adhesive or the like, an electrode forming material is laminated on one surface of the film by a method such as vapor deposition. Alternatively, it may be formed on the electrode by a coating method from the viewpoint of workability.

The electrostatic information recording medium of the present invention records information on the charge holding layer as a distribution of electrostatic charges. Therefore, the electrostatic information recording medium can have various shapes depending on the information to be recorded or the recording method.
For example, when it is used for a camera, it becomes a general film (single frame, continuous frame) shape, a disk shape, a card shape, and even when recording digital information or analog information with a laser or the like, a tape shape or a disk shape. , Or a card shape.

The support 15 shown in FIG. 1 (a) strongly supports the electrostatic information recording medium, and if it has a certain level of strength to support the charge retention layer,
The material and the thickness thereof are not particularly limited, and include, for example, a flexible plastic film, metal foil, paper, glass, plastic sheet, metal plate (which can also serve as an electrode).
There is a case where a rigid body such as is used and the light transmittance is also required. When light transmittance is required, the antireflection property can be imparted by adjusting the layer having the antireflection effect and the film thickness capable of exhibiting the antireflection effect, or by combining the layers, if necessary. When the electrostatic recording medium has a flexible film, tape, disk, or card shape, a flexible plastic film is used as the support, while a rigid sheet is used when strength is required. Inorganic materials such as glass are used.

The electrode 13 is formed on the support 15, and the material thereof is not limited as long as the specific resistance value is 10 ⁶ Ω · cm or less, and it may be an inorganic metal conductive film, an inorganic metal oxide conductive film or a quaternary ammonium. It is an organic conductive film such as salt. Such an electrode is formed on the support by a method such as vapor deposition, sputtering, CVD, coating, plating, dipping, and electrolytic polymerization. The film thickness needs to be changed depending on the electric characteristics of the material forming the electrodes and the applied voltage at the time of recording information.
It is about 000Å and is formed over the entire surface between the support and the charge retention layer or according to the formation pattern of the charge retention layer.

The electrostatic information recording medium shown in FIG. 1 (b) does not have the support 15, but such an electrostatic information recording medium is obtained by forming a charge retention layer into a film. It is produced by forming an electrode layer on the surface of the charge retentive layer by a vapor deposition method, a sticking method or the like.

The electrostatic information recording medium of the present invention has a plastic film as a protective film on the surface of the electrostatic information recording medium for preventing the damage of the surface of the electrostatic information recording medium and the attenuation of the information charges after recording the information, or It is advisable to coat it with a plastic solution or to form it to a film thickness of several hundred liters to several tens of μm by a vapor deposition method or the like, and information reproduction is possible at this level.

When it is necessary to impart photosensitivity to the electrostatic information recording medium at the same time, the charge holding layer may be provided on the surface of the photoconductor having the photoconductive layer by coating or adhesion.

Next, an electrostatic information recording / reproducing method for the electrostatic information recording medium of the present invention will be described. FIG. 2 is a diagram for explaining the electrostatic information recording method. In the figure, 1 is a photoconductor, 5 is a support, 7 is an electrode, 9 is a photoconductive layer, 17 is a power supply, and 18 is information light.

First, a transparent electrode 7 made of ITO having a thickness of 1000 Å is formed on a support 5 made of glass having a thickness of 1 mm.
A photoconductive layer 9 having a thickness of about 10 μm is formed on the photoconductor 1
Are configured. As shown in FIG.
On the other hand, the electrostatic information recording medium 3 is arranged via a gap of about 10 μm.

Then, as shown in FIG.
A voltage is applied between the electrodes 7 and 13 by. The figure shows
This is an example of the case where the photoconductor side is the positive electrode. In a dark place, the photoconductive layer 9 is a high-resistor, so if the voltage applied to the void is not higher than the discharge start voltage according to Paschen's law, no change occurs between the electrodes. When a voltage equal to or higher than the discharge start voltage is applied to the air gap by the external power source, discharge occurs, electric charges are accumulated in the electrostatic information recording medium, and the state continues until the discharge start voltage is reached, resulting in fog charge. When the light 18 is incident from the side of the photoconductor 1, the photoconductive layer 9 in the portion where the light is incident exhibits conductivity and discharge occurs,
Electric charges are accumulated in the electrostatic information recording medium. Further, even if there is a uniform fog charge in advance, further charges are accumulated in the portion where the light is incident. Then, the power supply 17 is turned off and the electrostatic information recording medium 3 is separated from the photoconductor 1 to complete the formation of the electrostatic latent image.

When electrostatic recording is performed by this electrostatic information recording method, high resolution can be obtained as in the case of silver salt photography, and it can be stored for a long time without being discharged.

As a method of inputting information to the electrostatic information recording medium of the present invention, there are a high resolution electrostatic camera method and a laser recording method. First, a high-resolution electrostatic camera uses the electrostatic information recording medium of the present invention instead of a photographic film used in a normal camera, and it is brought into close contact with a photoconductor or is opposed at a certain interval. A voltage is applied between both electrodes to form an electrostatic latent image according to an incident optical image, and an optical shutter can be used and an electric shutter can also be used. In addition, a prism is used to separate the optical information into R, G, and B light components, and a color filter for extracting the light as parallel light is used to form one frame with three sets of electrostatic information recording media separated into R, G, and B.
Alternatively, the R, G, and B images are arranged on one plane so that one set constitutes one frame, so that color photography can be performed.

As a recording method using a laser, as a light source, an argon laser (514.488 nm),
A helium-neon laser (633 nm), a semiconductor laser (780 nm, 810 nm, etc.) can be used, and the surface of the photoconductor and the electrostatic information recording medium are brought into close contact with each other.
A voltage is applied so that they are opposed to each other at regular intervals. In this case, it is advisable to set the photoconductor electrode in the same polarity as the carrier of the photoconductor. In this state, laser exposure corresponding to an image signal, a character signal, a code signal, and a line drawing signal is performed by scanning. Analog recording such as images is performed by modulating the light intensity of the laser, characters, codes,
For digital recording such as line drawing, turn on the laser light.
Performed by OFF control. In addition, dot generator ON-
It is formed by applying OFF control. Incidentally, the spectral characteristics of the photoconductive layer in the photoconductor do not have to be panchromatic, as long as it has sensitivity to the wavelength of the laser light source.

In the electrostatic information recording medium of the present invention, instead of using a photoconductor for recording, an electrostatic recording medium using an electrode needle head or an ion flow head, an optical printer such as a laser printer, or Although it can be used as a recording medium by electron beam, ion implantation, etc., it is particularly suitable as an electrostatic information recording medium using a photoconductor.

Next, a method of reproducing the electrostatic information recorded on the electrostatic information recording medium will be described. FIG. 3 is a diagram showing an example of a potential reading method in the electrostatic information recording / reproducing method.
The same numbers as in FIG. 1 indicate the same contents. In the figure, 21
Is a potential reading unit, 23 is a detection electrode, 25 is a guard electrode, 27 is a capacitor, and 29 is a voltmeter.

In order to reproduce information from the electrostatic information recording medium in which the information charges are accumulated, first, the potential reading section 21 is made to face the surface of the electrostatic information recording medium, and the detection electrodes 23 are charged by the charges accumulated in the fine particle layer. The generated electric field acts to generate an induced charge on the detection electrode surface in an amount equal to that of the charge on the electrostatic information recording medium. Since the capacitor 27 is charged with an equal amount of electric charge having a polarity opposite to the induced electric charge, a potential difference according to the accumulated electric charge is generated between the electrodes of the capacitor, and the voltmeter 29 reads this value to obtain the electric potential of the information electric charge. be able to. Then, the electrostatic latent image can be output as an electric signal by scanning the surface of the electrostatic information recording medium with the potential reading unit 21. Note that the detection electrode 23 alone causes an electric field (electric force line) due to electric charges in a wider range than the detection electrode facing portion of the electrostatic information recording medium to act to lower the resolution. Therefore, the guard electrode 25 grounded around the detection electrode should be provided. It may be arranged. As a result, the lines of electric force are oriented in the direction perpendicular to the surface, so that the lines of electric force act only on the portion facing the detection electrode 23, and the potential of the portion substantially equal to the area of the detection electrode is read. be able to. The accuracy and resolution of potential reading vary greatly depending on the shapes and sizes of the detection electrodes and guard electrodes, and the distance between the electrodes and the electrostatic information recording medium. Therefore, it is necessary to design the optimum conditions according to the required performance. As a method of reading the potential, it is also possible to optically read by the photoelectric effect using an optical crystal such as LiNbO ₃ having an electro-optical effect or an organic optical material such as a liquid crystal.

FIG. 4 is a diagram showing a schematic structure of the electrostatic information reproducing method. In the figure, 31 is a potential reading device, 33 is an amplifier,
Reference numeral 35 is a CRT, and 37 is a printer.

In the figure, the potential reading device 31 detects the charge potential, the detected output is amplified by the amplifier 33, and the CRT is detected.
It can be displayed at 35 and can be printed out at the printer 37. In this case, it is possible to arbitrarily select and output the portion to be read at any time, and it is possible to repeatedly reproduce. It can also be read optically using a material whose optical properties change with an electric field, such as an electro-optic crystal. Further, since the electrostatic latent image is obtained as an electric signal, it can be used for recording on another recording medium or the like, if necessary.

[0031]

The polystyrene resin constituting the charge retentive layer has a high glass transition temperature of 35 ° C. or more and high heat resistance, and a low water absorption rate of 0.04% or less. Since there is little charge leakage, and polystyrene resin is soluble in various solvents, it has excellent processability, and is particularly excellent in coating to make the film thickness uniform over a certain area or to make it as thin as several μm. is there. However, polystyrene resins generally have low chargeability and cannot be used as they are as a material for forming a charge retention layer.

The present inventors have found that the addition of an insulating organic material having no photoconductivity to polystyrene resin improves the charge retention characteristics, particularly the positive charge retention performance.
Although the detailed reason for this is unknown, it is believed that the addition of an insulating organic substance will cause positive charge trap sites in the polystyrene resin, improving the positive charge retention performance. It is useful as an electrostatic information recording medium used in combination with the body.

In reproducing the information, the accumulated electrostatic information can be easily detected by measuring the potential difference between the electrode and the surface potential, and an electric signal corresponding to the electrostatic latent image can be detected. It can be output and displayed on a CRT, or printed out by a printer. Also,
Since the information storage means is an electrostatic charge unit, the information stored can be of high quality and high resolution.

The present invention will be described below with reference to examples.

[0035]

Example 1 0.0195 g of p-phenylenediamine was added to Picolastic D125 (Rika Hercules Co., Ltd.).
Manufactured, trade name): xylene = dissolved in 20 g of a mixed solvent of 3: 7 to prepare a 0.33 wt% solution.

This solution was applied to an ITO transparent electrode (film thickness: about 5
Spin coating (10 Å, resistance value 80 Ω / □) (10
It was applied at 00 rpm for 20 seconds). It was put in an oven at 100 ° C. for 1 hour and dried to obtain an electrostatic information recording medium having a film thickness of 5 μm.

A charge-retaining layer of the electrostatic information recording medium was charged by a corona charger so as to have a surface potential of +180 V and -180 V, and then 60 ° C. as an acceleration test.
The charge retention performance under a high temperature condition of 25% RH was measured. The result is shown in FIG.

The charge retention performance was also measured under the high humidity conditions of 40 ° C. and 95% RH. The result is shown in FIG.

In the production of the above electrostatic information recording medium,
An electrostatic information recording medium was prepared in the same manner as described above except that a solution having an organic substance concentration of 3.3% by weight and 0.1% by weight was used. It was measured by the method. The results are shown in Fig. 7.

As can be seen from the figure, the electrostatic information recording medium of the present invention is particularly excellent in the ability to retain positive charges,
Further, it can be seen that the retention performance improves as the concentration of the organic substance increases.

[0041]

Example 2 0.0179 mg of phenothiazine was dissolved in 20 g of a mixed solvent of Picolastic D125 (trade name, manufactured by Rika Hercules Co., Ltd.): xylene = 3: 7,
A 0.3 wt% solution was prepared. Using this solution, an electrostatic information recording medium was obtained under the same conditions as in Example 1.

The charge holding layer in the electrostatic information recording medium was charged by a corona charger so that the surface potentials were +170 V and -170 V, and then 60 ° C. as an acceleration test.
The charge retention performance under a high temperature condition of 25% RH was measured. The result is shown in FIG.

The charge retention performance was also measured under the high humidity condition of 40 ° C. and 95% RH. The result is shown in FIG.

[0044]

Example 3 0.0284 mg of 2,4,7-trinitro-9-fluorenone was dissolved in 20 g of a mixed solvent of Picolastic D125 (trade name, manufactured by Rika Hercules Co., Ltd.): xylene = 3: 7, and 0 A 0.47 wt% solution was prepared. Using this solution, an electrostatic information recording medium was obtained under the same conditions as in Example 1.

The charge holding layer of the electrostatic information recording medium was charged by a corona charger so that the surface potentials were + 170V and -170V, and then an acceleration test was conducted at 60 ° C.
The charge retention performance under a high temperature condition of 25% RH was measured. The result is shown in FIG.

The charge retention performance was also measured under the high humidity condition of 40 ° C. and 95% RH. The result is shown in FIG.

In the production of the above electrostatic information recording medium,
Organic substance concentration 0% (no addition), 0.0047% by weight,
An electrostatic information recording medium was prepared in the same manner as above, except that 0.0094% by weight and 0.047% by weight solutions were used.
The charge retention performance one day after the charging treatment was measured by the same method. Results are shown in FIG.

As can be seen from the figure, the electrostatic information recording medium of the present invention is particularly excellent in positive charge retention performance,
It can be seen that the retention performance is improved as the concentration is increased.

[0049]

Example 4 (Method for producing single-layer organic photoconductor) 10 g of poly-N-vinylcarbazole (manufactured by Anan Perfume Co., Ltd.), 10 g of 2,4,7-trinitrofluorenone, 2 g of polyester resin (binder: Byron) 200 TOYOBO Co., Ltd.), a glass substrate (1 mm thick) in which a mixed solution having a composition of 90 g of tetrahydrofuran (THF) was prepared in the dark and In ₂ O ₃ —SnO ₂ was sputtered to a film thickness of about 1000 Å. Was coated with a doctor blade and dried in air at 60 ° C. for about 1 hour to obtain a photoconductor having a photoconductive layer with a thickness of about 10 μm. Moreover, in order to completely dry, it was used after being naturally dried for another day.

(Electrostatic Information Recording / Reproducing Method) With this photosensitive member,
The electrostatic information recording medium prepared in Example 1, in which 0.33% by weight of p-phenylenediamine was added to the charge retention layer, was used as a spacer with a polyester film having a film thickness of 10 μm, and the surface of the electrostatic information recording medium was as described above. It was grounded by facing the photoconductive layer surface of the photoreceptor. Then, ± 600V between both electrodes
DC voltage was applied.

When voltage is applied, the illuminance is 1000
The exposure is performed for 1 second using a Lux halogen lamp as a light source, and the formation of the electrostatic latent image is completed.

Then, the potential difference between the electrode and the medium surface was measured as shown in FIG.
The surface potential of V and -100V was measured by a surface electrometer, and the surface potential at the unexposed portion was ± 10V.

The surface charge was measured after leaving it for 30 days at room temperature and normal humidity, and it was found to be +90 V and -80 V, and the positive charge was particularly well maintained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing each aspect of an electrostatic information recording medium of the present invention.

FIG. 2 is a diagram for explaining a method of recording electrostatic information on an electrostatic information recording medium according to the present invention.

FIG. 3 is a diagram showing an example of a DC amplification type potential reading method.

FIG. 4 is a diagram showing a schematic configuration of an electrostatic information recording / reproducing method using the electrostatic information recording medium of the present invention.

FIG. 5 shows a change with time in the charge retention rate of an electrostatic information recording medium in which p-phenylenediamine was added to the charge retention layer, which was stored under the conditions of 60 ° C. and 25% RH. It is a figure.

FIG. 6 shows changes with time in the charge retention rate of an electrostatic information recording medium in which p-phenylenediamine was added to the charge retaining layer, stored under the conditions of 40 ° C. and 95% RH. It is a figure.

FIG. 7 shows an electrostatic information recording medium in which p-phenylenediamine was added to the charge retention layer at 60 ° C., 25% RH, 4%.
It is a figure which shows the relationship between the charge retention rate in the state preserve | saved under conditions of 0 degreeC, and 95% RH, and the p-phenylenediamine concentration in a charge retention layer.

FIG. 8 is a view showing a change with time of the charge retention rate in a state where the electrostatic information recording medium having phenothiazine added in the charge retention layer is stored under the conditions of 60 ° C. and 25% RH.

FIG. 9 is a view showing a change with time of the charge retention rate in a state where the electrostatic information recording medium having phenothiazine added in the charge retaining layer is stored under the conditions of 40 ° C. and 95% RH.

FIG. 10 shows an electrostatic information recording medium in which trinitrofluorenone was added to the charge retention layer at 60 ° C. and 25% RH.
FIG. 3 is a diagram showing a change with time of a charge retention rate in a state of being stored under the condition of.

FIG. 11 shows an electrostatic information recording medium in which trinitrofluorenone was added to the charge retention layer at 40 ° C. and 95% RH.
FIG. 3 is a diagram showing a change with time of a charge retention rate in a state of being stored under the condition of.

FIG. 12 shows an electrostatic information recording medium in which trinitrofluorenone was added to the charge retention layer at 60 ° C. and 25% R
It is a figure which shows the relationship between the charge retention rate in the state preserve | saved under the conditions of H, 40 degreeC, and 95% RH, and the trinitrofluorenone concentration in a charge retention layer.

[Explanation of symbols]

1 is a photoconductor, 3 is an electrostatic information recording medium, 5 is a support, 7 is an electrode, 9 is a photoconductive layer, 11 is a charge retention layer, 13 is an electrode,
Reference numeral 15 is a support, 17 is a power source, 18 is information light, 21 is a potential reading unit, 23 is a detection electrode, 25 is a guard electrode, 27
Is a capacitor, 29 is a voltmeter, 31 is a potential reading device, 33 is an amplifier, 35 is a CRT, and 37 is a printer.

Claims (1)

[Claims] 1. In an electrostatic information recording medium in which a charge retention layer is laminated on at least an electrode layer, the charge retention layer has a molecular weight of 1
An electrostatic information recording medium comprising a polystyrene resin of 0 ³ to 10 ⁶ to which an insulating organic substance having no photoconductivity is added.