JPH0323901B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrostatic recording medium having a dielectric layer on a conductive layer, and particularly to an electrostatic recording medium used for high-density recording such as a linear density of 16 lines/mm. In the electrostatic recording method, a voltage pulse is applied from the front or both sides of an electrostatic recording medium in which a recording layer made of a high-resistance insulating resin is provided on a support that has been subjected to conductive treatment. This method forms an electrostatic latent image, visualizes it with colored powder (toner), and fixes it by an appropriate method to obtain a permanent visible image, and is used in facsimiles, printers, etc. A conventional electrostatic recording medium is one in which a dielectric layer made of an insulating resin or the like is provided on a support that has been subjected to conductive treatment. The surface resistivity of the dielectric layer of such an electrostatic recording material varies depending on the type of insulating resin and the amount of pigment added, but is temporarily about 10 ¹⁰ to ^{10 16} [Ω]. The surface resistivity is measured using a ring type resistance meter. Measure the current value when the voltage is 100V, and calculate the surface specific resistance value from this current value and voltage. In an electrostatic recording medium in which the surface resistivity of the dielectric layer is 10 ¹⁰ to 10 ¹⁶ [Ω], when the line density is 8 lines/mm, almost no thin lines or missing dots are observed. However, in the case of high-density electrostatic recording with a linear density of 12 lines/mm, 14 lines/mm, or 16 lines/mm, the diameter of the electrode where the discharge occurs becomes smaller, and the pulse width becomes smaller, resulting in non-discharge. Missing thin lines and missing dots occur. Currently, the majority of facsimile electrodes are multi-stylus heads with single-sided electrode control. As for the electrode structure, for example, 55 control electrodes are arranged in two rows, and 0.08 mmφ multi-stylus pins are arranged in one row between the electrodes, and when the number of pins is 8/mm, the total number of pins is 1728. By changing the pin diameter of this multi-stylus, the scanning line density can be changed.
It can be used for low-density recording and high-density recording. Table 1 shows a comparison between low density recording and high density recording.

[Table] Conventional facsimiles were mostly low-density recordings of 8 dots/mm. However, for local government fax systems that transmit family registers, etc., the resolution is low at 8dots/mm, making thin lines, fine letters, and seal impressions unclear, necessitating high-density recording. Thus
By using a multi-stylus such as 16dots/mm, it has become possible to clearly transmit thin lines, fine letters, seal impressions, etc. In addition, as the size of a single recorded dot has become sufficiently small, it has become possible to easily reproduce halftones using dithering (changing the number of halftone dots per unit area), making it possible to reproduce photoelectronics. It is also ideal for The purpose of the present invention is to achieve the above-mentioned linear density of 12 lines/
The goal is to completely eliminate thin lines and missing dots in high-density electrostatic recording of mm, 14 lines/mm, and 16 lines/mm. That is, when providing a dielectric layer of an electrostatic recording material, for a prescription in which the surface resistivity of the dielectric layer made of high-resistance resin, pigment, etc. is 10 ¹¹ to 10 ¹⁶ [Ω],
A very small amount of water-soluble polymer electrolyte is added to adjust the surface resistivity of the dielectric layer to 4×10 ⁶ to 1×10 ¹⁰ [Ω]. Or the surface resistivity of the dielectric layer is 10 ¹¹ to 10 ¹⁶
A trace amount of water-soluble polymer electrolyte is coated on the surface of a conventional electrostatic recording material of [Ω], and the surface specific resistance ρs of the dielectric layer is set to 4×10 ⁶ to 1×10 ¹⁰ [Ω]. The electrostatic recording material whose dielectric surface resistivity obtained in this way is 4×10 ⁶ to 1×10 ¹⁰ [Ω] has a linear density of 12 lines/mm, 14 lines/mm, or 16 lines/mm. There is no undischarge in high-definition recording, and there are no thin lines or missing dots from low humidity to high humidity. Also, while maintaining good recording density from low humidity to high humidity, there is no unevenness in solid black areas, no side marks, ghosts, or fog. The fields of application of this invention and the effects expected therein are as follows. The electrostatic recording material of the present invention has a linear density of 8 lines/mm, 12
Even when changing the line/mm, 14 lines/mm, and 16 lines/mm, there is no thin line missing or missing dots from low humidity to high humidity.
In addition, it maintains good recording density from low humidity to high humidity, and there are no unevenness in black solid areas, no dents, ghosts, or fog, making it ideal for facsimile communications and photographs used in local governments such as family register extracts, seal certificates, etc. It is ideal for reproducing tones using dithering using electrostatic recording, and for use as a plotter as an output device for drawings such as CAD. That is, the present invention provides an electrostatic recording material comprising: (1) a dielectric layer containing a high-resistance resin and a trace amount of water-soluble polymer electrolyte provided on a conductive layer; An electrostatic recording material characterized in that the resistance is 4×10 ⁶ to 1×10 ¹⁰ Ω. (2) An electrostatic recording material comprising a dielectric layer consisting of two layers: a high-resistance resin layer and a layer coated with a trace amount of water-soluble polymer electrolyte on the surface of the dielectric layer on the conductive layer, which The surface resistivity of the dielectric layer is 4×10 ⁶ ~1
This is an electrostatic recording medium characterized by a resistance of ×10 ¹⁰ Ω. The electrostatic recording material of the present invention has a conductive layer, that is, a support that has been subjected to a conductive treatment, and a dielectric layer made of a copolymer of acrylic, polyester, or vinyl chloride/vinyl acetate.
Butyral is used alone or in combination; pigments are calcium carbonate, clay, titanium dioxide, silica, alone or in combination; and very small amounts of water-soluble polyelectrolytes are added. Alternatively, a trace amount of water-soluble polymer electrolyte is coated on the surface of a conventional electrostatic recording material whose dielectric layer has a surface resistivity of 10 ¹¹ to ^{10 16} [Ω]. Examples of water-soluble polymer electrolytes include polyvinylbenzyl quaternary ammonium chloride, polystyrene sulfonate, polymer substances containing acrylic acid or methacrylic acid ester constituent units of polyalkylene glycol having a quaternary ammonium group, and epichlorohydrin-based polymers. There are resins, etc. The surface resistivity of the dielectric layer of the electrostatic recording material thus obtained is 4×10 ⁶ to 1×10 ¹⁰ [Ω], and in high-definition electrostatic recording with a linear density of 16 lines/mm, etc. An electrostatic recording material can be obtained that has no fine lines or missing dots from low humidity to high humidity, and has no unevenness in solid black areas, no dents, no ghosts, and no fog. Note that when electrostatic recording is performed using an electrostatic recording material in which conductive fine powder is added to the dielectric layer, horizontal discoloration becomes noticeable in solid black areas, making it unsuitable for practical use. Examples and comparative examples are shown below. Example 1 Calcium carbonate 15 parts by weight Acrylic resin 15 〃 MEK 70 〃 Polyvinylbenzyl quaternary ammonium chloride 0.2 〃 were dispersed using a homogenizer and dispersed by dry weight on 50 g/m ² high-quality paper that had been previously subjected to low resistance treatment.
The surface resistivity of the dielectric layer of the electrostatic recording paper obtained was coated with a wire bar so that the resistance was 10 g/ ^m2 .
It was 10 ⁷ [Ω]. Comparative Example 1 Calcium carbonate 15 parts by weight Acrylic resin 15 〃 MEK 70 〃 was dispersed using a homogenizer, and the dry weight was distributed on 50 g/m ² high-quality paper that had been previously subjected to low resistance treatment.
The surface resistivity of the dielectric layer of the electrostatic recording obtained was coated with a wire bar so that it was 10 g/ ^m2 .
It was 10 ¹³ [Ω]. Example 2 Methanol 70 parts by weight Water 30 〃 Polyvinylbenzyl quaternary ammonium chloride 0.05 〃 was applied onto the electrostatic recording paper obtained in Comparative Example 1 using a wire bar to give a dry weight of 0.05 g/m ² death,
The surface resistivity of the dielectric layer of the obtained electrostatic recording material was 8×10 ⁶ [Ω]. Comparative Example 2 Calcium carbonate 15 parts by weight Acrylic resin 15 〃 MEK 70 〃 Electrostatic zinc oxide 0.5 〃 were dispersed using a homogenizer, and then dispersed by dry weight on 50 g/m ² high-quality paper that had been previously subjected to low-resistance treatment.
The surface resistivity of the dielectric layer of the electrostatic recording paper obtained was coated with a wire bar so that the resistance was 10 g/ ^m2 .
It was 10 ⁹ [Ω]. Above Example 1, Example 2, Comparative Example 1, Comparative Example 2
The electrostatic recording paper obtained was recorded using a high-speed electrostatic facsimile machine while varying the linear density and temperature/humidity. The results of these records are shown in Table-2.

【table】

【table】

[Table] Comparing Example 1, Example 2, and Comparative Example 1, both Example 1 and Example 2 were good in terms of thin lines and missing dots even when the line density was increased.
In Comparative Example 1, when the line density was increased, thin lines and dots were frequently missing. Furthermore, in terms of recording density, Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were all good. On the other hand, while the unevenness in the black solid area was good in both Examples 1 and 2, small horizontal voids occurred frequently in Comparative Example 2. Also regarding fog and ghost 4
Both examples were good. As described above, the electrostatic recording material of the present invention maintains sufficient recording density from low humidity to high humidity, has no thin lines or missing dots during high-definition recording, and has no unevenness, fogging, or ghosting in solid black areas. do not have.

Claims (1)

[Scope of Claims] 1. An electrostatic recording material comprising a dielectric layer containing a high-resistance resin and a trace amount of water-soluble polymer electrolyte on a conductive layer, wherein the surface resistivity of the dielectric layer is 4×
An electrostatic recording material characterized in that the resistance is 10 ⁶ to 1×10 ¹⁰ Ω. 2. An electrostatic recording material provided with a dielectric layer consisting of two layers: a high-resistance resin layer and a layer coated with a trace amount of water-soluble polymer electrolyte on the surface of the dielectric layer on the conductive layer,
The surface resistivity of the dielectric layer is 4×10 ⁶ to 1×10
An electrostatic recording medium characterized by a resistance of ¹⁰ Ω.