JPS6388558A - Electrostatic recording body - Google Patents

Abstract

PURPOSE:To improve contrast and transparency of image by providing a layer contg. a synthesized hectorite clay as a main component on at least one surface of a transparent or translucent substrate body, and by providing a recording layer on the obtd. substrate. CONSTITUTION:The layer 2 contg. the synthesized hectorite clay as the main component is provided on at least one surface of the transparent or translucent substrate body 1, followed by providing the recording layer 3 on the obtd. layer 2. The synthesized hectorite clay is a white powder shown by the formula, and has property of swelling, dispersing, solation or gelation in water. Said clay can be formed into an uniform sol or gel in the water until 10% concentration. The good coated film having conductive property is formed by applying the obtd. uniform sol or gel solution of said clay on a plastic sheet, followed by drying it. The aqueous solution of said clay is applied on the sheet by means of a wire bar, an air knife, a roller or a gravure printing, etc. The coated amount of said clay is 1-20g/m<2>, preferably, 1.5-10g/m<2> per one side layer of the substrate, by weight basis. Thus, high transparency and high image density over the range from a low humidity to a high humidity are obtd., and the inexpensive titled body is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrostatic recording medium for purposes such as second diazo original drawings, drawing inspection, and permanent preservation.

[Prior Art] An electrostatic recording medium is used in a CAD system, in which a transparent or translucent plastic sheet support is subjected to conductive treatment and a recording layer is provided thereon.

In this case, the methods of sN treatment include: ■ Processing the surface with a polymer containing components such as known quaternary ammonium salts and sodium sulfonate; ■ Performing metal sputtering or vapor deposition; ■ Performing tin oxide, indium oxide, or conductive There are known methods such as kneading powdered zinc oxide or the like into the sheet during production, or coating the surface of the sheet with a resin that serves as a binder.

However, method (■) does not produce satisfactory images in an atmosphere with a relative humidity of less than 25% and more than 80%, and method (2) is technically difficult to control the thickness of the metal film from 1 to 100%, and the manufacturing cost is high. There are high disadvantages. The Zarani (■) method has poor transparency and is also expensive.

[Information] The object of the present invention is to provide an electrostatic recording material that can produce satisfactory images in a wide range of relative humidity from 20 to 85%, has high transparency, and is inexpensive.

[Structure] The present invention has been made to achieve the above object, and includes a transparent or translucent support, a layer containing synthetic hectorite clay as a main component on at least one side, and a recording layer on top of the layer. This is an electrostatic recording medium characterized by the following.

The synthetic hectorite clay used in the present invention is a white powder having the general formula % and has the property of swelling, dispersing, sol or gelling in water. Commercially available products include Laponite S and RDS from Labortain Industries, and Mizuriki Night SH1, 2, and 3 from Mizusawa Chemical Co., Ltd.

This product can be prepared as a homogeneous sol or gel in water up to a concentration of about 10%, and can be applied to a plastic sheet [,
When dried, it forms a good film and exhibits electrical conductivity.

Coating [For the purpose of improving the uniformity, adhesion, and coating properties of the coating, it is preferable to mix it with a surfactant, water-soluble resin, etc. Without this, it is difficult to uniformly apply an aqueous solution onto a sheet of polycarbonate, polypropylene, polyvinyl chloride, polyethylene, polyester, or the like. To make it translucent, foreign substances such as pigments are mixed in and painted, or the surface is roughened into a pine-like shape.

As a surfactant, as its hydrophilic atomic group, -CO
ONa, saft, -0SO3Na, sulfonate,
-3OaNa, polyhydric alcohol, glycerin, solpit, pentaerythritol, alkif-4-sulfite, alkif-4-sulfite, alkyl-fu-t-sulftate, -
Those containing (EO)n can be used, and the coating solution contains o,
By adding about oi to 1%, repellency can be prevented, but the type and amount thereof are determined by experiment.

Examples of water-soluble resins include sodium polyacrylate, polyacrylate ester and its copolymer, sodium maleate polymer and its copolymer, CMC, PVA, ten flour,
7/14:4'/-1, a polymer having a sodium sulfonate group, etc. is suitable.

Its raw material content is less than 50% solids, and if it exceeds this, the low dependence of electrical resistance on temperature and humidity, which is a characteristic of synthetic hectorite clay, will be lost, and the electrical resistance value will increase, resulting in deterioration of image quality. do.

The aqueous solution of synthetic hectorite clay thus obtained is applied onto the above-mentioned sheet by a known method such as a wire bar, an air knife, a roll, or a gravure. The coating amount is preferably 1 to 20 g/m2, more preferably 1.5 to 10 g/m2 on one side, in terms of dry weight.

In particular, when it is desired to improve adhesiveness, it is advisable to coat the sheet surface with polyvinyl acetate or its copolymer, epoxy resin, etc. in advance. In this case, coating can be performed without adding a surfactant to the synthetic hectorite clay solution.

Sheets are generally fabricated from double-sided co-synthetic hectorite clay.

A recording layer containing a known high-resistance resin and pigment as main components is provided on the transparent conductive base treated for conductivity in this manner.

FIG. 1 is a sectional view illustrating the structure of an embodiment of the present invention, in which 1 is a plastic sheet, 2 is a synthetic hectorite clay layer, and 3 is a recording layer.

Next, the present invention will be explained by specific examples and comparative examples.

Example 1 The following liquid was coated on both sides of a 70μ thick polyester sheet to form a conductive base with a dry coating weight of 2.5 g/m 2 on each side.

Synthetic hectorite clay (Laponite S, Laporte Industries M) 7 parts 1 part polyacrylic acid soda
2 parts by weight water
90 parts by weight Container 5 with a dry recording layer of the following formulation on one side.
It was coated and dried to a coating density of 9/m2.

Polyvinyl butyral 15 parts by weight Calcium carbonate 15 parts by weight Methanol
70m early section (dispersed for 24 hours with a ball mill) The electrostatic recording material thus created was printed using an electrostatic printer plotter (manufactured by Toyo Denki Seizo Co., Ltd., Drastem 8600).
As shown in the table, good images were obtained from low humidity to high humidity.

Example 2 Polyvinyl acetate was coated on both sides of the polyester sheet 1 of Example 1 so that the dry coating amount was 1 (J/12) (each side). Laponite S) 7 judanbe CM0
1 part by weight water
92 parts by weight of the mixture was applied and dried so that the dry adhesion amount was 4.6 (J/m 2 on the surface and 3.0111/I112 on the back), and a recording layer was formed on the surface in the same manner as in Example 1. .

Then, image formation was performed in the same manner as in Example 1. The results are shown in the table.

Comparative Example 1 A solution of polyvinylbenzyltrimethylammonium chloride was applied as a conductive material to both sides of the polyester sheet of Example 1 to obtain a conductive base with an adhesion of 2.5 (1/m 2 ) on each surface. It was carried out in the same manner as in Example 1.

Comparative Example 2 As a conductive material, 10 parts by weight of S n 02 pigment (FF202, manufactured by Sumitomo Chemical Co., Ltd.) PVA
4 moves ω part water
Dry 86 parts by weight.
The same procedure as in Example 1 was carried out except that the coating was carried out so that the coating became II2.

In addition, the relationship between surface resistivity and relative temperature in Examples and Comparative Examples is not shown in FIG. 2.

[Effects] The electrostatic recording material of the present invention has high transparency and image density from low humidity to high humidity, and can be ISed at a low price. The high transparency means that when superimposed on the original drawing for checking, the underlying drawing can be clearly seen, which is useful in practice, and when used as a second diazo original drawing, the diazoli printing speed increases.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining an example of the layer structure of the present invention, and FIG. 2 is a graph showing the relationship between surface resistivity and relative humidity in Examples and Comparative Examples. 1... Plus deck sheet 2... Synthetic hectorite clay layer 3... Recording layer

Claims (1)

[Claims] 1. An electrostatic recording material comprising a transparent or translucent support, a layer containing synthetic hectorite clay as a main component provided on at least one side, and a recording layer provided thereon.