JPS6211340B2 - - 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 layer of metal or metal compound. 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 provides an electrophotographic transfer device that can be used to prevent copying of information once created by means such as copying or printing in the confidential document copy prevention device previously proposed by the present inventors. The purpose is to improve the seat. Conventionally, aluminum-deposited paper for discharge recording, for example, is known as a metal-containing sheet.
This material has base paper 1a as shown in the cross-sectional view in the drawing.
A carbon layer 1b, an aluminum vapor deposition layer 1c, and a white conductive layer 1d are provided thereon. 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. In addition, some machines suffered from transfer defects in high-temperature environments. Furthermore, if the metal layer and the paper or plastic film sandwiching it are made thinner 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. As a result of extensive research into the size of metal in a metal-containing layer in order to eliminate the above-mentioned conventional drawbacks, the present invention has developed a proximity detector that can be used when dispersing metal powder or metal pieces in a metal-containing adhesive layer. The size of metal powder or metal pieces that can be detected by this method is 0.001 mm or more in thickness, 1 mm or more in length and width, and the presence of metal powder or metal pieces in the adhesive layer. This is based on the finding that the amount is required to be 45% by weight or more. The size of metal powder or metal piece is 0.001mm thick
less than 1 mm, the length and width are less than 1 mm, or the proportion of metal powder or metal pieces in the adhesive layer is less than 1 mm.
If it is less than 45% by weight, it will be difficult to detect with a proximity detector. Furthermore, if the ratio of metal powder or metal pieces in the adhesive layer exceeds 65% by weight, the adhesive function will deteriorate and it is unsuitable. 45-65% by weight is preferred. As the adhesive in the present invention, acrylic resin emulsion, polyethylene resin emulsion, acrylic-ester copolymer, vinyl acetate-acrylic copolymer, acrylic adhesive, synthetic rubber adhesive, etc. can be used. In addition, examples of the raw material metal for the metal powder and metal flakes include aluminum, iron, copper, etc., but aluminum is most preferred from the viewpoint of manufacturing. Next, the electron-containing electrophotographic transfer sheet of the present invention will be specifically explained using examples, and comparative examples will also be shown to compare the effects thereof. Example 1 Aluminum thin pieces measuring 1 mm x 1 mm in length and width and 0.003 mm in thickness were mixed in an acrylic adhesive in an amount of 55% by weight, stirred, and then coated on release-treated paper to a thickness of 150 μm using an applicator and dried. This metal-containing adhesive was transferred to a high-quality paper with a basis weight of 43 g/m ² , and a high-quality paper with a basis weight of 43 g/m ² was laminated thereon. Example 2 Aluminum thin pieces measuring 1 mm x 1 mm in length and width and 0.003 mm in thickness were mixed with acrylic resin emulsion at 60% by weight, stirred, and coated on high-quality paper with a basis weight of 43 g/m ² . It was layered with 43 g/m ² high-quality paper and dried. Comparative Example 1 An aluminum flake measuring 0.8 mm x 0.8 mm and 0.003 mm thick was mixed with acrylic adhesive at 60% by weight, coated on release-treated paper with an applicator, and dried. This metal-containing adhesive was transferred to a high-quality paper with a basis weight of 43 g/m ² , and a high-quality paper with a basis weight of 43 g/m ² was laminated thereon. Comparative example 2 Aluminum powder with a diameter of 0.06 mm is applied to acrylic adhesive.
The weight percentages were mixed, coated on release-treated paper with an applicator, and dried. This metal-containing adhesive has a basis weight of 43
g/m ² high-quality paper, and then add a layer with a basis weight of 43
g/m ² high-quality paper was laminated. The test data of electrophotographic copying machine copyability and copying machine running properties of the sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2 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]

The figure is a cross-sectional view of a conventional aluminum vapor-deposited paper for discharge recording. In the figure, 1a...Base paper, 1b...Carbon layer, 1
c... Aluminum vapor deposited layer, 1d... White conductive layer.

Claims (1)

[Claims] 1. On both sides of a metal-containing adhesive layer, the adhesive layer contains 45 to 65% by weight of metal powder or metal flakes that can be detected by a proximity detector with a thickness of 0.001 mm or more and a vertical and horizontal length of 1 mm or more. A metal-containing transfer sheet for electrophotography, characterized in that it is laminated with paper or plastic film.