JPH0376836B2 - - Google Patents

Description

[Detailed description of the invention]

[Purpose of the invention] (Field of industrial application) Electrophotographic copying machines have become increasingly popular in recent years, but this has also made it easier to leak confidential documents and forge or alter banknotes and securities. What is being done to people is becoming a negative influence. The present invention relates to a copy prevention method for eliminating these disadvantages. (Prior Art) In order to achieve the above object, methods using components that are transparent to visible light and develop color when exposed to light from a copying machine, such as impregnation with leuco bodies, photochromic substances, etc. Methods of applying coating compositions containing substances, methods of utilizing metamery effects, methods of using fluorescent dyes, etc. are known. However, leuco bodies, fluorescent dyes, etc. have the disadvantage of poor weather resistance and deteriorate over time, and even if other methods are used, it is impossible to completely copy normal printed matter that is printed in dark colors on white paper. No system has been developed that can prevent it. (Problems to be Solved by the Present Invention) The present invention provides a method for preventing copying that can practically completely prevent copying by various commonly used transmission type or reflection type copying machines. [Structure of the Invention] (Means for Solving the Problem) The present invention relates to a method for preventing copying, which is characterized in that a resin layer containing transparent red iron oxide is formed on the entire surface of a document, a desired part, or an appropriate pattern. be. The transparent red iron used in the present invention is well known in the color material industry, and has ultrafine particles compared to normal red iron. When this transparent red iron oxide is sufficiently dispersed in a resin and made into a thin layer, it has a slightly yellow color but is transparent and transmits visible light, and has excellent ultraviolet blocking properties.
An invention (Japanese Unexamined Patent Publication No. 72193/1983) has been made in which it is used as an ultraviolet-blocking transparent packaging material. In the present invention, by applying a resin layer containing transparent red iron oxide onto a document, the document can be fully read with the naked eye, and when an attempt is made to copy it with various copying machines, a certain part of the resin layer becomes black.
This is based on the new knowledge that reading becomes impossible or difficult. The method of forming a resin layer containing transparent red iron oxide on a document is not particularly limited, but for example,
A resin layer can be formed directly on the document by printing, coating, or in some cases, a dipping method, a resin layer can be formed on a transparent plastic film using the same method as above, or a resin layer can be formed in plastic. Knead transparent red red iron to make a film. There are methods of heat-sealing these films onto documents, methods of pasting them onto documents using adhesives, adhesives, etc., and methods of enclosing documents using this plastic film.
The latter method, particularly the method using an adhesive, is extremely simple and preferred. At this time, it is preferable to prepare a film in which an adhesive is provided on the film and a release layer is further superimposed thereon. The amount of transparent red iron oxide is 0.3 to 10 g/m ² , preferably 0.5 to several g/m ² . If it is too small, there will be no copy prevention effect, and if it is too large, the document will be difficult to read. The resin may be appropriately selected depending on the method of forming the resin layer. For example, in the case of a printing method, a resin known in the art may be used, taking into consideration its suitability for printing, and in the case of coating, a resin known in itself may be used. Since the resin layer containing transparent red iron oxide itself exhibits a pale yellow color, it does not give a bothersome feeling to the reader, but it is possible to mix and use pigments or dyes of other hues depending on preference. For example, when a blue pigment such as copper phthalocyanine is mixed, the hue becomes green to indigo. Moreover, copper phthalocyanine is preferable because it absorbs long wavelength light. In addition, metals such as aluminum can be deposited to a thickness of about 60 to 100 Å by vapor deposition or sputtering.
When applied to a plastic film before or after forming a resin layer, the unique light gray color provides a calm tone without impairing visual transparency, resulting in favorable effects such as not tiring the eyes. [Example] The present invention will be explained below with reference to Examples. In the example,
Parts represent parts by weight, and % represents weight %. Example 1 Transparent red iron TRANS OXIDE RED (Hilton-
Davis) 10.0 parts Polyether type urethane varnish (Sample LQ390 manufactured by Sanyo Chemical) 32.0 parts Nitrocellulose (SS1/8 manufactured by Daicel) 8.0 parts Ethyl acetate 2.0 parts Isopropyl alcohol 24.0 parts Methyl ethyl ketone 24.0 parts The above composition was placed in a steel bowl. The mixture was kneaded for 24 hours to obtain gravure ink with a pigment content of 10% and a resin content of 12%. The obtained gravure ink was coated with a polyester film (Toyobo Polyester Film E-5100, film thickness 25 μm) so that the film thickness was as shown in Table 1.
m) Beta gravure printing was carried out using a conventional method and dried. Acrylic adhesive Olivine on release treated paper
BPS-8170 (manufactured by Toyo Ink Mfg. Co., Ltd.) is applied to a dry film thickness of 25 μm, and the adhesive is transferred to the printed surface of the above-mentioned solid gravure printed polyester film using a conventional transfer method and laminated. created a film. The obtained laminated film was pasted on the surface of a printed matter with characters printed with corner ink, and the visual transparency of the characters was observed. The anti-copying effect was tested using Xerox 4600 (manufactured by Fuji Xerox Co., Ltd.). The results are shown in Table-1.

[Table] Example 2 Transparent Red Iron Garla TRANS in Example 1
OXIDE RED 10.0 parts, transparent red iron TRANS
OXIDE RED 6.0 parts and orange pigment PV Red HFG
A gravure ink was obtained in the same manner as in Example 1, except that the mixture was replaced with a mixture consisting of 4.0 parts (manufactured by Hoechst). The obtained gravure ink was subjected to solid gravure printing on a polyester film (Toyobo Polyester Film E-5100) to a film thickness shown in Table 2 and dried. Hereinafter, a laminated film was obtained in the same manner as in Example 1, and its visual transparency and anti-copying effect were tested. The results are shown in Table-2.

[Table] Example 3 The gravure ink obtained in Example 2 was applied to the vapor-deposited surface of a polyester film (Polyester Film E-5100 manufactured by Toyobo Co., Ltd.) on which aluminum was vapor-deposited to a film thickness of 60 Å using a conventional method. Solid printing was performed in the same manner and dried. Hereinafter, a laminated film was obtained in the same manner as in Example 1, and its visual transparency and anti-copying effect were tested. The results are shown in Table-3. When the printed characters in the filler ink were visually observed for a long time through the obtained laminated film, the characters were not tiring to the eyes and had a calm color tone.

【table】

[Table] Example 4 The gravure ink obtained in Example 2 was applied to the vapor-deposited surface of a polyester film (polyester film E-5100 manufactured by Toyobo Co., Ltd.) on which aluminum was vapor-deposited to a film thickness of 60 Å using a conventional method. Solid printing was performed in the same manner and dried. Thereafter, in the same manner as in Example 1, an adhesive was transferred to the non-printing surface of the vapor-deposited polyester film that had been subjected to betagravure printing to prepare a laminated film. The laminated film obtained in the same manner as in Example 1 was tested for visual transparency and anti-copying effect. The results are shown in Table 4. When the printed characters in the filler ink were visually observed for a long time through the obtained laminated film, the characters were not tiring to the eyes and had a calm color tone.

[Table] Comparative example 1 Acrylic adhesive Olivine on release treated paper
BPS-8170 (manufactured by Toyo Ink Mfg. Co., Ltd.) was applied to a dry film thickness of approximately 25 μm, and aluminum was deposited using a conventional transfer method to obtain a film thickness of 60 Å. Film E-5100, film thickness
A laminated film was prepared by displacing the adhesive on the non-evaporated surface (25 μm). Hereinafter, the visual transparency and anti-copying properties of the laminated film obtained in the same manner as in Example 1 were tested. As shown in Table 5, the visual transparency was very good, but there was no anti-copying effect at all. Comparative Example 2 In the same manner as Comparative Example 1, the thickness of the deposited film was determined by the usual method.
Polyester film with aluminum vapor deposited to a thickness of 400 Å (Toyobo Polyester Film E)
A laminated film was created by displacing the adhesive on the vapor-deposited surface of 5100). Hereinafter, the visual transparency and copy-proofing properties of the laminated film obtained in the same manner as in Example 1 were tested. As shown in Table 5, the anti-copying effect was sufficient, but there was no visual transparency at all.

〔Effect of the invention〕

As described above, the present invention provides a method of preventing copying that can practically completely prevent copying by various types of copying machines, whereas conventional copying prevention methods cannot completely prevent copying of ordinary printed surfaces. According to the present invention, there is no problem with weather resistance, not only has sufficient visual transparency, but also has a calm color tone that can be viewed for a long time without tiring the eyes, and has a sufficient Copy protection is possible.

[Brief explanation of drawings]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 1 is a sectional view showing one embodiment of Examples 1 and 2, FIG. 2 is a sectional view showing one embodiment of Example 3, and FIG. 3 is a sectional view showing one embodiment of Example 4. DESCRIPTION OF SYMBOLS 1... Transparent plastic film, 2... Vapor deposition layer, 3... Resin layer containing transparent red iron oxide, 4... Adhesive layer, 5... Document.

Claims (1)

[Claims] 1. A copy prevention method characterized by forming a resin layer containing transparent red iron oxide on the entire surface of a document, in a desired part, or in an appropriate pattern.