JPS6250815B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in an electrophotographic transfer sheet that can be detected by a proximity detector, allows originals to be prepared by any means such as copying, and contains a metal layer. With the spread of office copy machines and fax machines,
It would be highly desirable to provide a practical means to prevent unauthorized copying of confidential documents or copyrighted records, and several methods have already been proposed. The present inventors also processed document sheets by vapor-depositing, coating, impregnating, pasting, etc. with metal, and also provided means for detecting and responding to the metal in document sheets in accordance with the scanning exposure process during copying. I proposed the device first. The present invention is an improvement of an electrophotographic transfer sheet that can be used to prevent copying of information once created by means such as copying or printing in the above-mentioned confidential document copy prevention device proposed by the present inventors. The purpose is to Conventionally, aluminum-deposited paper for discharge recording, for example, is known as a metal-containing sheet.
This material has a base paper 1 as shown in the cross-sectional view in Figure 1.
A carbon layer 1b, an aluminum vapor-deposited layer 1c, and a white conductive layer 1d are provided on the layer a. Even if such a metal-containing sheet is passed through an electrophotographic copying machine to obtain a copy, the electric charge escapes due to its low electrical resistance, and therefore transfer cannot be performed, so it can be used as an electrophotographic transfer sheet. Things did not previously exist. Furthermore, the present inventors have already filed a patent application for an electrophotographic transfer sheet containing metal (Japanese Patent Application No. 146,823/1982), and the present invention is a further improvement on this. The present invention provides an electrophotographic transfer sheet that can be detected by a proximity detector, has sufficient paper passability for an electrophotographic copying machine, and can be used not only as printing paper but also as an electrophotographic transfer sheet, and can be used to create manuscripts by any means. It provides: When a sheet having the structure described in the earlier application is passed through a copying machine such as the product name Xerox, if the metal layer and the paper or plastic film sandwiching it are made thicker, the sheet becomes too stiff and jams occur in the copying machine. Something happened. Additionally, there were machines that caused transfer defects in high-humidity environments. Furthermore, if the metal layer and the paper or plastic film sandwiching it are made thinner in order to prevent jamming, the metal layer and the paper or plastic film will wrinkle during the manufacturing process, making it difficult to obtain a sheet with a satisfactory three-layer structure. Furthermore, even if the product could be manufactured successfully, the problem of poor transfer in a high humidity environment could not be solved. The proximity detector is capable of detecting any metal in a non-contact state by utilizing changes in the impedance of the oscillation coil of the high frequency oscillation circuit due to eddy current loss, and its internal structure is well known, so details will be omitted. The present invention has been made in order to solve the above-mentioned conventional drawbacks. For example, as shown in FIG. The specific resistance is 10 ¹⁵ Ω・cm
This was achieved by a structure in which the above layers are further provided with a metal-containing layer 4 such as a metal thin film layer or a metal vapor deposited layer thereon, and further the above-mentioned high resistance layer and paper are disposed in this order. Furthermore, as shown in FIG. 3, it is also possible to omit one high-resistance layer. The reason why the configuration of the present invention as described above can improve transfer defects at high humidity is that the presence of a high resistance layer makes it difficult for the charge to dissipate by the transfer corotron of a PPC (electrophotographic copying machine). It is. Materials that can be used as the high-resistance layer include melt-extruded films such as polyethylene, polypropylene, ethylene-vinyl acetate copolymers, and ionomers, and curing reactive resins such as polyester and polyurethane. The electrophotographic transfer sheet of the present invention will be explained below using Examples and Comparative Examples. Example 1 Commercially available high-quality paper with a basis weight of 30 g/m ² and aluminum foil with a thickness of 7 μm were laminated together by a polyethylene extrusion lamination method. The thickness of the polyethylene at this time was 20μ, and the specific resistance value of the polyethylene was 3×10 ¹⁶ Ω·cm. Furthermore, the surface to which the aluminum foil was not bonded was again bonded to a commercially available high-quality paper with a basis weight of 30 g/m ² by the polyethylene extrusion lamination method to obtain a laminated paper containing aluminum foil in the middle. Example 2 A two-component reactive polyester resin was coated on a 7 μm thick aluminum foil, and after drying, a high quality paper with a basis weight of 85 g/m ² was adhered by pressure. The thickness of the polyester resin at this time was 10 μm, and the specific resistance value was 2×10 ¹⁵ Ω·cm. Furthermore, a two-component reactive polyester resin was applied to the non-bonded side of the aluminum foil, and after drying, the basis weight was 35.
g/m ² high-quality paper was attached by pressure bonding. Comparative Example 1 Polyacrylic acid ester emulsion was coated on a commercially available high-quality paper with a basis weight of 40 g/m ² , and dried by overlaying it with 7 μm thick aluminum foil. The dry weight of polyacrylic acid ester is 10 g/m ² and the specific resistance value is 8×10 ¹³
It was Ω・cm. Commercially available high-quality paper coated with polyacrylic acid ester emulsion was laminated onto the aluminum foil. Regarding the sheets obtained in Examples 1 to 2 and Comparative Example 1, the test data of electrophotographic copying machine copying performance and copying machine runnability are shown in the following table.

[Table] From the above table, the excellent properties of the sheet of the present invention are clear.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional aluminum vapor-deposited paper for discharge recording, and FIGS. 2 and 3 are sectional views of an example of a metal-containing transfer sheet for electrophotography according to the present invention.
The figure shows a case where both sides have high resistance layers, and FIG. 3 shows a case where only one side has a high resistance layer. In the figure, 1a...Base paper, 1b...Carbon layer, 1
c... Aluminum vapor deposited layer, 1d... White conductive layer, 2...
...Paper, 3...High resistance layer, 4...Metal-containing layer.

Claims (1)

[Claims] 1 In an electrophotographic metal-containing transfer sheet in which paper is laminated like a sandwich on both sides of a metal layer that can be detected by a proximity detector, there is a specific resistance of 10 ¹⁵ Ω between the paper and the metal layer on at least one side.・
A metal-containing transfer sheet for electrophotography, characterized in that a high resistance layer of cm or more is interposed.