KR100581130B1 - Method for preparing Sheet having a Conductive Security Thread and the Security Paper Prepared Thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a conductive silver wire sheet and a security paper using the same, comprising a step of printing an ink composition containing a fibrous conductive pigment on one or both sides of the transparent plastic film to form a conductive layer of the conductive silver wire sheet It relates to a manufacturing method and a security paper using the same. The security paper according to the present invention has excellent electrical characteristics, and thus has high utility as a device-sensing element, and it is easy to print additional functions such as fluorescent lamps, thereby obtaining various effects, and excellent anti-counterfeiting effect.

Fibrous conductive pigments, security paper, machine-sensitive, transparent plastic film, clear text

Description

Method for manufacturing conductive silver wire sheet and security paper using same {Method for preparing Sheet having a Conductive Security Thread and the Security Paper Prepared Thereby}

Figure 1 is an exemplary view showing a forgery preventing silver wire sheet having a printed layer formed by printing a black or colored letters or patterns on a transparent plastic film according to the prior art.

FIG. 2 is an exemplary view showing a clear text type silver wire sheet formed by depositing and removing a metal coating layer on a transparent plastic film according to the related art.

Figure 3 is an exemplary view showing an anti-counterfeiting conductive silver wire sheet prepared according to the present invention.

Figure 4 is an exemplary view showing another anti-counterfeiting conductive silver wire sheet prepared according to the present invention.

5 is an exemplary view showing another anti-counterfeiting conductive silver wire sheet prepared according to the present invention.

Figure 6 is an exemplary view showing another anti-counterfeiting conductive silver wire sheet prepared according to the present invention.

Figure 7 is an exemplary view showing another anti-counterfeiting conductive silver wire sheet prepared according to the present invention.

Explanation of symbols on the main parts of the drawings

1, 10: transparent plastic film

2, 12: character pattern printing layer

3: clear text type metal deposition layer

11: conductive layer containing fibrous conductive pigment

13: clear text printing layer

14: clear text printing layer containing fibrous conductive pigment

15: fluorescent printing layer

The present invention relates to a method of manufacturing a conductive silver wire sheet and a security paper using the same, and more particularly, a method of manufacturing a conductive silver wire sheet used for the purpose of preventing forgery when manufacturing papers of securities, including banknote checks and the like. It relates to the security paper used.

When manufacturing paper used for various securities papers such as banknote checks and securities, it is manufactured by inserting a silver wire cut into a predetermined size to prevent forgery and alteration.

As a general prior art for producing a silver wire sheet, a forgery-resistant silver wire sheet as illustrated in FIG. 1 is known, for example, can be seen through US Patent Nos. 5,314,739, 4,813,989 and 5,419,424. The anti-counterfeiting silver wire sheet on which the pattern shown in FIG. 1 is printed has a printed layer 2 on which a black or colored letter or pattern is formed on a transparent plastic film 1 by a conventional printing method. In addition, a metal film may be used instead of the transparent plastic film as needed, and an fluorescence treatment may be additionally performed on the upper side of the printing layer 2, and electrical conductivity, magnetic properties, hologram characteristics, It is also manufactured by applying various factors such as color conversion. The silver wire sheet thus manufactured is cut to a width of about 0.5 to 5 mm and inserted into the paper when the paper is manufactured to be used as an anti-counterfeiting element of securities, which also plays a very important role as a security element.

In addition, U.S. Patent No. 4,652,015 manufactured a silver wire sheet by depositing a metal material such as aluminum on a film, and manufactured a security paper by inserting the silver wire formed by cutting the silver wire sheet into a predetermined size when manufacturing paper. The reason for inserting the metal-deposited silver wire is to obtain an optical effect that, when the metal layer is transmitted, looks dark in light but does not appear well in reflected light.

As a further improvement of the above methods, the most widely used method is an anti-counterfeiting silver wire sheet as shown in FIG. 2, which is described in US Patent No. 4,652,015, European Patent Publication No. 319,157, and Korean Patent Registration No. 111546. have. Referring to FIG. 2, the silver wire sheet forms a clear text type metal deposition layer 3 by a deposition and demetallization method such that letters or patterns appear transparently on the transparent plastic film 1, The optical effect is mainly obtained. This security hidden line has electrical characteristics because it is composed of a metal layer as well as an optical purpose. It is known to use this property as a mechanical sensitive element. In addition, a metal ink such as metacin was used to provide both optical effects and electrical conductivity of light reflection.

However, their manufacturing process is so common that it is widely used commercially at present, and also technically can be easily manufactured by the general public has a problem that the anti-counterfeiting effect is gradually reduced, such as easy to steal or imitate. In addition, in the case of general metal ink including metacin, the metal particles are dispersed only. Therefore, when the metal printing layer is formed by printing using only the metal ink, almost no conductivity is generated. It is difficult to use, and there is a problem in the aptitude for manufacturing silver wire.

As a more technically improved method, Korean Patent No. 69251, British Patent Nos. 1,552,853 and 1,604,463 are known, which allow partial exposure of metal deposition or clear text-type silver lines, so that the metal during radiation for forgery Since the hidden line turns black due to the reflection of, it is used as a very important security factor for copiers and scanners. It is also composed of only a metal layer, so it has electrical characteristics and can be used as a mechanical sensitive element.

In addition, Korean Patent No. 146374 discloses a method of supplementing electrical characteristics by a sputtering method using indium tin oxide in a clear text type. However, indium-tin oxide is a very expensive material and is not suitable for use for silver wire and thus lacks practicality.

As described above, the Korean Patent Nos. 69251 and 146374 have an optical density of about 0.3 to 0.7 or an aluminum layer, or as a thin film of about 20 mg / m 2 to obtain a conductivity and a translucent effect. In some cases, it may be possible, but due to the manufacturing process for depositing a thin film, there is a significant problem in manufacturing a uniform quality for the entire hidden line sheet, in particular sputtering method is significantly slower during the manufacturing process costs There is a problem in application such as a significant increase.

In addition, the anti-counterfeiting silver wire sheet described in International Publication No. 99451 has a clear text portion and a colorless fine color on a transparent plastic film in order to give a multifunctionality by combining the above-mentioned clear text and colored characters and mixing various characteristics. It is made by printing a colored text pattern layer repeatedly formed with colored text patterns printed with letters or patterns. The clear text part is transparently formed with letters or patterns inside the metal layer. When it is transparent, the other metal layer part meets the optical characteristics such as the basic reflection of the hidden line by the optical effect, and the colored character pattern part uses a predetermined type of character or a pattern using a colored ink or the like for printing methods such as gravure. By printing (recording) or by fluorescence Colored colors are used as anti-falsification factors by using optical properties, but the original purpose for preventing forgery to prevent copying is as the colored part is partially reproduced by color copying or scanner. There is a problem that is inadequate, there is a problem that cannot be easily adjusted so that various functional characteristics such as the density and fluorescence of characters are well displayed by printing, and the problem that the manufacturing process is too complicated. However, it is too weak to be a device sensitive element.

However, in accordance with the global trend that the automation by the machine is rapidly made, the security element of the security paper is rapidly increasing the demand to have the basic self-security characteristics as well as the function of device sensitivity.

Accordingly, it is an object of the present invention to solve the above-mentioned problems of the prior art, and to further improve, to provide a method for producing a conductive silver wire sheet, which has a forgery preventing effect and is useful as a device sensitive element.

In addition, another object of the present invention is to use the conductive silver wire sheet produced by the above method, to obtain the basic effect and electrical conductivity by the letter and pattern of the silver wire, fluorescence, etc., and is generally used by giving the optical effect according to the metal reflection It can be used as a substitute for metal-deposited silver wire, but it can provide quality papers and other additional functions to provide security papers that can greatly improve anti-counterfeiting effects.

Method for producing a conductive silver wire sheet according to the present invention for achieving the above object, comprising the step of printing an ink composition containing 10 to 40% by weight of a fibrous conductive pigment on one or both sides of the transparent plastic film to form a conductive layer It is done by

In addition, another method of manufacturing a conductive silver wire sheet according to the present invention, the step of printing an ink composition containing 10 to 40% by weight of a fibrous conductive pigment on a transparent plastic film to form a conductive layer and a clear text portion or Printing the character pattern.

In addition, another method for producing a conductive silver wire sheet according to the present invention, by printing a mixture of an ink composition containing 10 to 40% by weight of a fibrous conductive pigment and an ink composition containing a metal powder on a transparent plastic film to form a conductive layer Forming step.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, the present invention prints a fibrous conductive pigment on a transparent plastic film, or by printing the fibrous conductive pigment to print a variety of patterns such as letters and pictures after the production of the conductive layer, or the fibrous on the ink itself when printing the pattern The conductive pigment is mixed to impart conductivity to the printed layer itself to produce a sheet for silver wire, and the silver wire sheet for anti-counterfeiting prepared as described above is cut to a predetermined size to produce a silver wire. The present invention relates to a security paper which is inserted or partially exposed into a paper by a conventional hidden line feeding method in a lamination system.

3 to 7 is an exemplary view showing a specific embodiment of the anti-counterfeiting silver wire sheet according to the present invention.

3 is an exemplary view showing a basic embodiment of the anti-counterfeiting silver wire sheet according to the present invention, which is formed by simply forming a conductive layer 11 using a fibrous conductive pigment on the upper surface of the transparent plastic film 10 without letters or patterns. It is manufactured for the purpose of using only electroconductive property.

The transparent plastic film 10 which is basically used when manufacturing the silver wire sheet is a plastic film which is commonly used, and is not particularly limited. For example, polyamide such as nylon, polyester, polyacryl , Polyvinylacetate, polyethylene, polyvinyl, and the like.

In addition, when the conductive layer 11 is formed on one side or both sides of the transparent plastic film 10, it prints by the normal gravure printing method.

The fibrous conductive pigments according to the present invention are selected from the group consisting of silver, titanium, aluminum, nickel, alloys of silver and palladium, and indium-tin oxide in ceramic fibers having a diameter of 0.3 to 0.5 µm and a length of 10 to 20 µm. It is prepared by coating a metal, and preferably prepared by coating silver or titanium by a vapor deposition method. One kind or two or more kinds of such fibrous conductive pigments can be used.

In general, conductive pigments include silver having excellent electrical conductivity, alloys of silver and palladium, indium-tin oxide, nickel, titanium, aluminum, or other metals such as carbon, or a combination of two or more metals. Most of these materials are used in paste or ink by mixing with appropriate ink materials. However, most of them are known to be suitable for products having a high viscosity and a large coating amount. In addition, problems such as miscibility with gravure inks and rapid increase in viscosity of metal powders or metal pastes used as general conductive pigments, and drying temperatures take 30 minutes at 150 ° C or more during drying, etc. Therefore, the present invention is not suitable for the production of silver wire sheets because it is not suitable for gravure printing conditions. Therefore, the present invention uses a conductive pigment obtained by coating a metal on ceramic fibers and mixing it with various additives, not a conductive pigment composed only of metal powder. It is done.

In addition, in particular, the gravure printing method generally has a significant limitation in the use of the conductive pigment because the ink has a low viscosity and a small amount of coating on the film, which is the basic printing medium. In this regard, in the case of using a general conductive pigment, when the electrical conductivity is measured after the production of the silver wire sheet, the electroconductive property does not appear well. However, as in the present invention, a fibrous conductive pigment is selected and mixed with a printing varnish or a metal ink to prepare a conductive ink and use it for the production of a silver wire sheet.

For example, the most commonly used aluminum particles and silver particles of 5 μm or less, which are known to have the highest conductivity, are added to the varnish for ink and the metal ink as much as possible in consideration of the workability, thereby preparing and printing the ink, respectively. As a result of measuring the electrical properties after manufacturing the silver wire sheet, the required electrical properties did not appear. The reason for this is that due to the characteristics of the gravure ink, it can be seen that the conductive pigments remaining in the printing layer after printing and drying are not interconnected to connect the electrical flow. In contrast, the conductive pigment made of a ceramic form having a length of about 10 to 20 μm and a diameter of about 0.3 to 0.5 μm according to the present invention facilitates the flow of electricity due to easier interconnection than conventional metal particles. . Examples of such fibrous conductive pigments include Otsuka Chemical's Dental WK 500 and SD 100. If the size of the ceramic fiber exceeds 20㎛ and 0.5㎛ does not insert into the groove for gravure printing there is a problem that does not print, if less than 10㎛ and 0.3㎛ there is a problem that the electrical conductivity is inferior. In the present invention, the electrical properties were compared and examined by measuring the electrical resistance, and in the case of the metal-deposited silver wire which is commonly used in the security paper, the electrical resistance value is about 4 to 6Ω as a result of the measurement. It is designed to obtain electrical conductivity, and it is possible to obtain an equivalent level of electrical conductivity or higher.

In addition, in order to construct the ink composition, varnishes, pigments, solvents, and the like suitable for application to the transparent plastic film may be included. The ink composition according to the present invention is characterized in that it comprises 10 to 40% by weight of the above-mentioned pigment, preferably 15 to 20% by weight. Other components are based on a conventional component and content. When the content of the fibrous conductive pigment is less than 10% by weight, the electrical conductivity to be obtained is weak. When the content of the fibrous conductive pigment is more than 40% by weight, the ink viscosity is greatly increased, which may cause problems such as poor printing or printing.

In the present invention, the varnish is preferably to use a polyester-based varnish. Moreover, the usage-amount of varnish is 50 to 80 weight%.

In addition, the solvent is used to make the paint easier to paint, but evaporates during drying and does not remain in the coating film. For example, alcohols such as ethanol and butyl alcohol, hydrocarbons such as naphtha and kerosene, ethyl acetate and butyl acetate Esters, ketones such as acetone methyl ethyl ketone, ethers such as butyl vertical solver may be used alone or in combination, and may be used at 5 to 10% by weight.

On the other hand, Figure 4 to Figure 7 is an anti-counterfeiting silver wire sheet of another embodiment according to the present invention, Figure 4 is a conductive layer containing a fibrous conductive ink composition by a gravure printing method on the upper surface of the transparent plastic film 10 ( 11) and a negative clear text printing layer 13 in which letters and patterns are formed in a negative shape like the clear text portion on the upper side thereof.

In general, in the case of depositing a metal layer on a transparent plastic film, the clear text part heats and evaporates a metal compound including a metal at high temperature and vacuum conditions to condense the evaporated metal on the surface of the target object to form a metal layer, and then the letters or patterns A method of demetallizing and producing by various methods is used.

In the present invention, when only the visible text characteristics of the clear text portion are required, the general ink is used to provide color and opacity by using a general printing method to exhibit the effect, and in particular, a partially exposed hidden line for using the optical characteristics of the metal. In the case of use, the metal ink containing metal particles such as aluminum, nickel, and silver may be mixed with a conductive pigment so as to exhibit the effect.

Figure 5 is a mixture of a conventional metallic ink and a fibrous conductive pigment according to the present invention on the upper surface of the transparent plastic film 10, the letter and the pattern is formed in a groove shape like a clear text portion, while the conductivity is given negative The clear text printing layer 14 containing the fibrous conductive pigment is formed.

As shown in the clear text portion, in order to impart color and optical properties due to metallic luster, a metal ink containing aluminum particles, which are commonly used, is used. In this case, the particle size of the metal ink is the electrical characteristics of the silver wire sheet. In order to show this efficiently, what is about 15-20 micrometers can be used.

FIG. 6 shows that only the conductive layer 11 according to the present invention is first formed without a letter or a pattern on the upper surface of the transparent plastic film 10, and a letter-pattern printed layer 12 is formed on the upper side of the transparent plastic film 10.

Figure 7 is a mixture of a conventional metallic ink and a fibrous conductive pigment according to the present invention on the upper surface of the transparent plastic film 10, the letter and the pattern is formed in a groove like a clear text portion, yet conductive is given negative The clear text printing layer 14 containing the fibrous conductive pigment is formed, and the ordinary fluorescent printing layer 15 is formed on the lower surface of the transparent plastic film 10 opposite to the printing layer 14. will be.

As shown in Figure 7, in addition to the conductive layer in the manufacture of the silver wire sheet prepared according to the present invention it can be very effective to increase the effect of the anti-counterfeiting by various additional functional printing by printing, such as fluorescence, magnetic.

In addition, it is preferable to perform printing such as fluorescence and magnetism on the upper surface of the conductive layer or on the opposite surface to the surface on which the conductive layer is located.

As described above, the present invention is to impart electrical conductivity to the anti-counterfeit silver wire sheet using a conventional printing method, for example, gravure printing method, by adding a fibrous conductive pigment to the general printing ink or metal ink, various effects To get it.

The anti-counterfeiting silver wire sheet according to the present invention manufactured as described above is easy to manufacture and excellent in electrical characteristics, and when used as a device sensitive element, it is possible to effectively perform anti-counterfeiting and authenticity discrimination.

In addition, the anti-counterfeiting silver wire sheet according to the present invention is made of a hidden line that is used (input) when finally cut to a width of 1 ~ 5mm to produce a security paper, the silver wire manufactured as described above is manufactured security paper In the process of making a paper or paper in the process of creating a paper-based paper in general, or inserted into the process (inserting) or after the paper is produced is put into the paper between the two paper manufacturing process during the manufacturing process, the hidden line is It can be made with a fully inserted or partially exposed interior of the paper.

The present invention is specifically described by the following examples and comparative examples. However, the present invention is not limited or limited by these Examples and Comparative Examples.

Example 1

20 wt% fibrous conductive pigment (Dental SD 100 (15 wt%), Dental WK 500 (5 wt%), Otsuka Chemical) was added to 75 wt% PET varnish (polyester compound, PET medium, Korean paint). The mixture was slowly stirred to allow sufficient mixing, and 2.5 wt% methyl ethyl ketone and 2.5% toluene were added again and stirred to prepare a fibrous conductive ink composition.

As shown in Fig. 4, the conductive ink composition according to the present invention is printed on a transparent plastic film 10 having a thickness of 25 microns, and the clear text portion 13 is formed thereon so that a character pattern is formed in a negative form such as a clear text portion. Printing by the gravure method was prepared for the anti-counterfeiting silver wire sheet.

The anti-counterfeiting silver wire sheet thus prepared was cut to a width of 1.2 mm to prepare a silver wire. When manufacturing the silver wire produced by the security paper in a conventional paper-line input method in the papermaking machine was inserted directly into a single paper to produce a concealed security paper that is completely inserted.

Example 2

Add 55% by weight of the fibrous conductive pigment (Dental SD 100, Otsuka Chemical) to 55% by weight of the Al paste for PET, and slowly stir it to be sufficiently mixed. Then, add 5% by weight of methyl ethyl ketone and 5% toluene again to stir. A fibrous conductive ink composition was prepared.

As shown in Fig. 4, the conductive ink composition according to the present invention is printed on a transparent plastic film 10 having a thickness of 25 microns, and the clear text portion 13 is formed thereon so that a character pattern is formed in a negative form such as a clear text portion. Printing by the gravure method was prepared for the anti-counterfeiting silver wire sheet.

The anti-counterfeiting silver wire sheet thus prepared was cut to a width of 1.5 mm to prepare a silver wire. When the manufactured silver wire was manufactured in a security paper, a partially exposed security paper in which the silver wire was partially exposed was prepared by inserting the silver wire into a paper using a conventional partially exposed silver wire manufacturing method in a paper machine.

Example 3

Into a 60% by weight varnish for PET, 35% by weight of fibrous conductive pigments (Dental SD 100 (25% by weight), Dental WK 500 (10% by weight), Otsuka Chemical) was added to the mixture by stirring slowly and 2.5% by weight of Methyl ethyl ketone and 2.5% toluene were added again and stirred to prepare a fibrous conductive ink composition. 70 wt% of the prepared fibrous conductive ink composition and 30 wt% of aluminum metal ink (Plain silver, manufactured by Samyoung Ink Co., Ltd.) having a particle size of 15 μm were mixed to obtain a mixed ink composition.

As shown in FIG. 7, the mixed conductive ink composition according to the present invention is printed on the transparent plastic film 10 having a thickness of 25 microns, and the fluorescent printed layer 15 is printed on the lower portion of the transparent plastic film 10 by a gravure method. An anti-counterfeiting silver wire sheet was prepared.

The anti-counterfeiting silver wire sheet thus prepared was cut to a width of 1.5 mm to prepare a silver wire. When manufacturing the silver wire produced by the security paper in a conventional paper-line input method in the papermaking machine was inserted directly into a single paper to produce a concealed security paper that is completely inserted.

Comparative Example 1

After the metal coating layer is deposited on the transparent plastic film 1 having a thickness of 25 microns in a general manner as shown in FIG. 2, the metal is selectively removed to form a character and a pattern so as to deposit a clear text-type metal deposition layer 3. The anti-counterfeit wire sheet was prepared, and the manufactured anti-counterfeit anti-counterfeit sheet was cut to a width of 1.5 mm to prepare a silver wire.

When the manufactured silver wire is manufactured in a security paper, a concealed security paper in which a hidden wire is completely inserted is introduced by a normal silver wire input method in a paper machine.

Comparative Example 2

When preparing the security paper was carried out in the same manner as in Comparative Example 1 except that a partially exposed security paper that is partially exposed to the silver wire was prepared by putting a silver wire into the paper by a conventional partially exposed silver wire manufacturing method in the ring paper paper machine.

In order to confirm the characteristics as the security element of the silver wire manufactured by the above examples and comparative examples, the electrical properties were compared by measuring the hidden wire itself, and after the insertion into the paper, the capacitance was examined to examine the maintenance of the electrical properties. The optical characteristics were examined when the hidden line was inserted into the paper by the change of color due to the reflection of light when the hidden line was inserted in the inside of the paper. Reviewed.

The results are shown in comparison with Table 1 below.

 Electric resistance (Ω)  Color variations Exterior When copying Example 1 4 to 6 Hard to see Does not appear Example 2 6 to 8 Metal color Changed black Example 3 7-10 Hard to see Does not appear Comparative Example 1 4 to 5 Hard to see Does not appear Comparative Example 2 4 to 5 Metal color Changed black

As can be seen from Table 1, the silver wire produced by the present invention is not only the effect of preventing forgery, but also excellent in electrical properties, it can be confirmed that the utility and its effect as an anti-counterfeiting and tampering element are very good overall. there was.

As described above, the anti-counterfeiting silver wire sheet according to the present invention has good electrical properties of the conductive layer, good optical properties when mixed with the conductive ink and the metal ink, and prints additional functions such as fluorescence by fluorescent printing. It is easy to do, and its effect is excellent, so that various effects can be effectively highlighted. In the case of the partially exposed silver wire type using the silver wire sheet by conductive printing using metal ink, the copying is different from the original. It has been reproduced to have a very excellent effect of the anti-counterfeiting function, and in particular, its electrical characteristics are excellent, which makes it highly usable as a device-sensing factor that is suitable for the automation of modern society.

In addition, the security paper according to the present invention is excellent in electrical characteristics, the utility as a device sensitive element is very high, it is easy to print additional functions such as fluorescence to obtain a variety of effects, the effect of the anti-counterfeiting function is excellent.

Claims (8)

In the manufacturing method of a conductive silver wire sheet, Printing an ink composition including 10 to 40% by weight of a fibrous conductive pigment on one or both sides of the transparent plastic film to form a conductive layer; Method for producing a conductive silver wire sheet for preventing forgery comprising a. In the manufacturing method of a conductive silver wire sheet, Forming a conductive layer by printing an ink composition including 10 to 40 wt% of a fibrous conductive pigment on a transparent plastic film; And Printing a clear text portion or a character pattern portion on the conductive layer; Method for producing a conductive silver wire sheet comprising a. In the manufacturing method of a conductive silver wire sheet, Forming a conductive layer by printing a mixture of an ink composition containing 10 to 40% by weight of a fibrous conductive pigment and an ink composition containing a metal powder on a transparent plastic film; Method for producing a conductive silver wire sheet comprising a. The ceramic fibrous conductive pigment according to any one of claims 1 to 3, wherein the fibrous conductive pigment is composed of silver, titanium, aluminum, nickel, silver, and palladium in a ceramic fiber having a diameter of 0.3 to 0.5 µm and a length of 10 to 20 µm. A method for producing a conductive silver wire sheet, characterized by coating a metal selected from the group consisting of alloys and indium-tin oxides. 4. The conductive material according to any one of claims 1 to 3, wherein a fluorescent or magnetic printed layer is printed on the upper surface of the conductive layer or on the opposite surface of the conductive layer to add a security function. Method for producing a hidden wire sheet. The method for producing a conductive silver wire sheet according to any one of claims 1 to 3, wherein the printing is gravure printing. The anti-counterfeiting silver wire sheet is manufactured by putting the silver wire obtained by cutting the silver wire sheet manufactured according to any one of claims 1 to 3 to a predetermined width into a circular paper machine or a double paper-lamination process. Security paper used. 8. The security paper using a forgery-preventing silver wire sheet according to claim 7, wherein the silver wire has a width of 1 to 5 mm.

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