JP3279212B2 - Anti-counterfeit paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called "threaded paper" type anti-counterfeit paper in which a thread having micro characters and / or micro images is inserted in the flow direction of the paper.

[0002]

2. Description of the Related Art Threaded paper in which a thread is inserted into a paper layer
Anti-counterfeit papers, which are referred to as, are well known. As a typical example of the thread, there is a thread as described later in detail. Paper that incorporates these requires extremely advanced technology for production, so it is very effective in preventing forgery,
As is well known, it is often used for banknotes and the like in various countries.

[0003] There are two main types of threaded paper. One is a type in which a thread is inserted into a sheet and is not exposed on the surface of the sheet, and the other is a type called "window-opening threaded paper" in which a part of the thread is exposed on the surface of the sheet.

In the former method of producing paper, a nozzle is inserted into a flow of stock in a sliced portion of a fourdrinier paper machine, and a thread is fed out while flowing water through the nozzle to form a paper formed on the paper net. A method of milling a filamentous material in the animal
No. 1-130309), a method of installing a thread-like material insertion device into the material flowing out of the flow box of a fourdrinier paper machine, and forming a thread while keeping the material in a non-contact state with the material by an air flow (particularly, (Kaihei 2-169790) Using a round paper machine having two or more tanks, feeding the filamentous material between the paper layers using a feeding pipe having irregularities on the inner wall by laminating two or more layers, A method of forming a thread between paper layers (Japanese Patent Publication No. 5-400)
No. 80) has been proposed.

As a method of manufacturing the latter "paper with a window opening thread", a belt mechanism having a groove through which a thread is passed at the tip of a convex portion of a guide having an uneven portion is buried in a stock suspension on a wire. Manufacturing method (Japanese Patent Publication No. 5-85680)
Or, use a net processed into an uneven shape for the upper net of a circular net paper machine,
A method in which a thread is inserted into a window opening portion by inserting a thread while making contact with an uneven portion on the surface of a net (US Patent No. 4462).
No. 866) or a method in which a compressed air nozzle is incorporated in a rotary drum on a wire of a fourdrinier paper machine, and a slurry on a thread-like material previously inserted into a paper web is intermittently blown off with compressed air to expose the thread-like material. (JP-A-6-272200) and the like have been proposed.

[0006] The "paper with window thread" that uses a thread as a thread-like material has a window opening whose thickness is reduced intermittently in the paper flow direction, and the thread is exposed at this window opening. Is the feature. Therefore, in the case of paper manufactured using a thread whose surface is not coated with an adhesive, rubbing the exposed part of the thread with a nail or the like may cause the thread to be easily peeled off, or the thread to rise during printing, which is fatal. Disadvantages. For this reason, a window-threaded paper is made using a thread coated with a heat-sensitive adhesive on both front and back sides, and the heat-sensitive adhesive applied to the thread when the paper is dried in the drying zone of the paper machine is removed. By melting or softening, measures have been taken to increase the peel strength by securely bonding the cellulose fibers and the threads that constitute the paper to each other. The reason why the heat-sensitive adhesive is applied to both sides of the thread is to ensure that a good adhesive force can be obtained regardless of which side of the thread is inserted into the paper.

[0007]

When a thermosensitive adhesive is applied to both sides of a thread in a window-threaded type forgery-preventing sheet, the face of the thread exposed at the window opening of the sheet is in the middle of the drying zone of the paper machine. Inevitably comes into contact with a cylinder dryer, a canvas, a touch roll and the like, and the heat-sensitive adhesive is melted or softened by heat, causing a problem of contaminating the surface of the cylinder dryer and the like. Also, by contact with a cylinder dryer, etc., the smoothness of the heat-sensitive adhesive applied to the thread surface exposed at the window opening part is lost, and especially in the thread having a metal deposition layer, the glittering property is reduced. This will cause a significant degradation problem. In addition, when the thread having the metal deposition layer is exposed at the window opening, the heat-sensitive adhesive applied on the metal deposition layer is partially removed, causing a problem that the metal deposition layer is easily corroded.

In order to manufacture a thread coated with a heat-sensitive adhesive on both sides, a method of slitting a film as a raw material coated with a heat-sensitive adhesive on both sides with a microslitter is employed. When a machine is used, it is difficult to apply a heat-sensitive adhesive to both surfaces of the film. That is, the heat-sensitive adhesive applied first on one side of the film melts and adheres to the touch roll when the heat-sensitive adhesive is applied on the other side for the second time. Therefore, it is necessary to select a type of heat-sensitive adhesive having a different melting temperature, or a troublesome measure such as using a floating drying method is required.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems. First, a thread having a heat-sensitive adhesive applied to only one side is manufactured, and a thread having no heat-sensitive adhesive applied is manufactured. The thread surface (the thread surface) is exposed at the window opening of the paper, and the heat-sensitive adhesive is applied to the thread surface (the thread back surface)
Tried to insert a thread during paper making so that the paper touched the inside of the paper. However, in this method, since there is no difference in appearance between the front and back surfaces of the thread, it is very difficult to visually determine whether or not the front and back surfaces have been correctly inserted when the thread is inserted during papermaking. A method in which the obtained paper is sampled by a take-up unit of a paper machine, a peeling force between the sled exposed at a window opening of the paper and the paper is measured, and it is determined whether or not the sled is inserted normally. However, in such a determination method, when a thread insertion error is determined, a considerable length of paper is produced, and the yield is greatly reduced. Such a decrease in yield is a very serious problem when paper is formed with many sheets inserted.

[0010] On the other hand, micro-characters and micro-images are formed on threads to further improve the forgery prevention effect. In this case, the micro-characters formed in the thread are “normal characters” and “reverse characters” as shown in FIG.
The design consists of a combination of The reason why such a design is adopted is that it is extremely difficult to control the front and back surfaces of the thread and insert the sheet into the sheet, so that either side of the thread may be inserted into the sheet. However, micro-characters that have a mixture of "normal characters" and "reverse characters" are not only uncomfortable,
The disadvantage is that they are so small that they are difficult to read.

Accordingly, the present invention makes it possible to easily and quickly identify the front and back surfaces of a thread even when only one side is coated with a heat-sensitive adhesive, and as a result, the front and back surfaces of the thread are correctly inserted during papermaking. If not, this thread can be immediately judged and returned to the correct insertion state.Furthermore, thread-based anti-counterfeiting paper has been made so that micro-characters containing only regular characters and micro-images containing only regular images can be viewed on the thread. It is an object to provide

[0012]

That is, the forgery prevention paper according to the first embodiment of the present invention is a forgery prevention paper in which a thread is inserted in the flow direction of the paper, wherein the thread is described with reference to FIG. A film a serving as a base, a micro-character of only a positive character and / or a micro-image of only a positive image comprising a metal-deposited layer b formed on the surface of the film, and a transparent film formed on the metal-deposited layer A print layer c made of ink, and a heat-sensitive adhesive layer d formed on the back surface of the film, and the ink forming the print layer is added with a dye / pigment that develops a color when irradiated with ultraviolet light. , The thread is inserted into a sheet so that a micro character of a normal character and / or a micro image of a normal image can be seen when viewed from the side.

Further, the forgery prevention paper according to the second embodiment of the present invention is a forgery prevention paper in which a thread is inserted in the flow direction of the paper, wherein the thread is, as described with reference to FIG. a, a micro-character of only reverse characters and / or a micro-image of only reverse image composed of a metal-deposited layer b formed on the back surface of the film, and a printing layer c of ink formed on the metal-deposited layer. A transparent heat-sensitive adhesive layer d formed on the back surface of the film so as to cover the printing layer, and a dye or pigment that develops color by irradiation with ultraviolet light is added to the ink forming the printing layer. When viewed from the front side of the paper,
Characterized in that the thread is inserted into the paper so that the inverted micro-characters and / or the inverted image micro-images can be seen through the transparent film as the normal character micro-characters and / or the normal image micro-images. is there.

In the anti-counterfeit paper of the present invention, the surface of the thread not coated with the heat-sensitive adhesive (thread surface)
Is inserted on the front side of the paper such that the surface of the thread coated with the heat-sensitive adhesive (the back surface of the thread) faces the back side of the paper. Therefore, when a window opening portion whose thickness is intermittently reduced in the paper flow direction is formed on the front side of the sheet and a thread is exposed at the window opening portion, the window opening thread is used. Since the thread surface exposed at the opening is not coated with the thermal adhesive, even if it comes into contact with a cylinder dryer, canvas, touch roll, etc. in the drying zone, the surface of these devices is contaminated by melting or softening of the thermal adhesive. There is no need to worry. In addition, the back surface of the thread coated with the heat-sensitive adhesive is melted or softened at the temperature of the drying zone of the paper machine and firmly adheres to the paper. There is no worry about the thread coming off.

When the sheet is irradiated with ultraviolet rays, the print layer c of the thread is colored. In the first embodiment shown in FIG. 6, the color development of the print layer c can be seen from the thread surface side. On the other hand, in the second embodiment shown in FIG. 7, the coloring of the printed layer c can be seen from the back side of the thread through the transparent heat-sensitive adhesive layer d. Therefore, even if the front and back are inserted reversely when inserting the thread during papermaking, the thread front and back can be easily identified by detecting the color development by ultraviolet irradiation,
The thread can be quickly inverted to return to the normal insertion state.

Furthermore, when viewed from the front side of the paper, micro-characters of only normal characters and / or micro-images of only normal images can be seen on the thread, so that normal characters and reverse characters appear to be mixed. Can be read without discomfort compared to conventional micro-characters such as.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a gift certificate using a forgery prevention paper made of a two-layered laminated paper, and FIG. This will be described with reference to FIG. The anti-counterfeit paper shown
The outermost paper layer 2 is composed of two layers, ie, the outermost paper layer 2 and the paper layer 3 other than the outermost layer. The outermost paper layer 2 intermittently extends in the vertical direction of the paper (the flow direction of the paper layer during papermaking). An opening 1 is provided. A thread 4 is inserted between the outermost paper layer 2 and the paper layer 3 in contact therewith, and the thread 4 is
It is exposed at the part. The side of the paper layer 2 is the front side of the paper. If necessary, a window made of a character or an image may be provided in the window opening portion 1, and the forgery-preventing ability can be further improved by applying both the threading and the character or image. Can be enhanced.

Next, in order to understand the present invention, a method for producing forgery prevention paper will be described with reference to specific examples. First, softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulphite pulp (NB
SP) or other non-wood pulp made from hemp, cotton, or straw as appropriate, beaten, and filled with filler, dry paper strength agent, wet paper strength agent, sizing agent, fixing agent, Retention improvers, drainage improvers, defoamers, dyes, coloring pigments, fluorescent agents, etc. are appropriately added, and usually 400 to 250 ml of freeness.
C. S. F. Prepare a stock adjusted to.

When producing anti-counterfeit paper by laminating two or more layers, a multi-tank-type round paper machine conventionally used generally for producing laminated paper can be used. FIG.
Fig. 2 shows an example of a two-tub-type mesh paper machine for producing a laminated paper comprising two paper layers 2 and 3 (Fig. 2), and a paper layer 3 other than the outermost layer without the window opening 1 is shown. (First tank before the last tank) 11 and second tank (final tank) 12 for forming the outermost paper layer 2 having the window opening 1
And

The upper net 12 of the cylinder 12a of the tank 12
As shown in FIG. 4, a mold 13 corresponding to the window opening 1 made of metal, resin, paper, or the like is attached to b with a thin metal wire, soldered, or attached with an adhesive. The shape of the mold 13 corresponding to the window opening is rectangular in the illustrated example, but may be any other shape such as a square, a circle, an ellipse, and the like.

When the mold 13 as shown in FIG. 4 is attached to the upper net 12b of the circular cylinder of the tank 12 for forming the outermost paper layer 2, the flow direction of the paper layer indicated by the arrow W (the vertical direction of the paper) In the direction X) corresponding to the window opening 1
And a non-window-opening portion 5 located between the window-opening portions
It is desirable that the mold 13 be intermittently mounted at an interval such that the ratio to the length Y corresponding to (FIG. 1) is 3: 1 to 1: 2. When the ratio of the window opening portion 1 is in this range, not only the effect of preventing wrinkles from occurring when the paper is continuously wound into a roll is ensured, but also the design of the paper surface is favorable.

An upper net without any work is mounted on the net cylinder 11a of the tank 11 of the net paper machine shown in FIG. The paper layer 3 made by the mesh cylinder 11a equipped with an upper net without any work is transferred to the blanket 14, and the mold 13 of the tank 12 is formed.
The outermost paper layer 2 made by the cylinder 12a is stacked on the cylinder 12a, and the paper having two paper layers is formed. The insertion of the thread 4 is performed at a position indicated by an arrow V immediately before the paper layer 3 and the paper layer 2 are overlapped. Examples of a method of feeding the thread 4 include a method of feeding the thread using a pipe having irregularities on the inner wall, as proposed by the same applicant as the present application in the above-mentioned Japanese Patent Publication No. Hei 5-40080. Can be adopted. Although the mold 13 attached to the mesh cylinder 12a is illustrated in some places in FIG. 3 and simplified, it is actually intermittently attached to the entire circumference of the mesh cylinder 12a.

The forgery prevention paper having the configuration shown in FIGS. 1 and 2 can be manufactured by the above-described two-layer assembling method. That is, in the outermost paper layer 2 formed by the mesh cylinder 12a to which the mold 13 is attached, the window opening 1 in which the stock is not placed is formed in a portion corresponding to the mold 13. By inserting the thread 4 between the paper layers 2 and 3 so as to enter into the window opening 1, the thread 4 is exposed in the window opening 1, and between the paper layers 2 and 3 in the non-window opening 5. The thread is buried at the point.

The anti-counterfeit paper of the present invention can be produced by using, for example, a fourdrinier paper machine as shown in FIG. . That is, in order to form the window opening 1 with a partially thinned paper layer and insert the thread 4 into the wet paper web 21 on the papermaking net 20 of the fourdrinier paper machine moving in the direction of the arrow W. A plurality of molds 2 having a shape corresponding to the window opening 1
3 is attached to the papermaking net 20
The wet paper is brought into contact with the upper wet paper 21 and rotated while pressing the wet paper. The dandy roll 22 is driven to rotate in the direction of the arrow by a suitable driving device. When the surface of the wet paper web 21 on the papermaking net is pressed by the dandy roll 22, the fibers of the wet paper web are pushed away at the portion corresponding to the mold 23, so that the window opening 1 of a thin paper layer is formed. At this time, the thread 4 is supplied to the center of the mold 23 and inserted into the wet paper 21.
Is exposed at the window opening 1. The adjacent mold 23
The fiber also moves between the mold and the mold 23, and the moved fiber covers the surface of the thread 4, thereby forming the non-window-opening portion 5 (FIG. 1). Instead of attaching the mold 23 to the upper net of the dandy roll 22, a projection having a shape corresponding to the window opening 1 may be formed on the upper net itself by a molding method or the like.

The anti-counterfeit paper of the present invention can also be manufactured by various methods other than those described above. For example, as proposed in Japanese Patent Publication No. 5-85680 introduced in the prior art as a method of manufacturing “paper with window opening thread”, a groove is provided at the tip of a convex portion of a guide having an uneven portion, and a thread is passed through this groove. In this state, the guide is embedded in the stock suspension on the wire of the fourdrinier paper machine, and when the moisture of the stock suspension is dehydrated downward from the wire and the paper layer is almost formed, the guide is raised. To form a window opening in which the thread is exposed at the portion in contact with the tip of the convex portion of the guide, as disclosed in JP-A-6-272200. A rotating drum with a built-in compressed air nozzle is installed on the wire, and the compressed air nozzle in the rotating drum intermittently blows compressed air from the compressed air nozzle into the wet paper web on which the thread is inserted. A method of intermittently forming a window opening where a thread is exposed by blowing off the slurry of the above-described method. As proposed in US Pat. No. 4,462,866, a net having a part of the surface processed into an uneven shape is a circular net. Used as the upper net of the paper machine, when the net is rotated in the tank containing the stock suspension, the thread is brought into contact with the uneven part on the net surface, and the thread is brought into contact with the convex part on the net surface. For example, a method of exposing the thread that has been exposed to the window opening can be adopted.

In producing the anti-counterfeit paper of the present invention, it is possible to apply starch, polyvinyl alcohol, various surface sizes, etc. to the paper surface during the paper making process using a size press device or the like. Further, if necessary, a machine calendering treatment or a super calendering treatment may be performed to improve the surface smoothness as appropriate.

Next, a method of manufacturing a thread used in the present invention will be described. Various films such as cellophane, polypropylene film, polyester film, nylon film, polyvinyl alcohol film, polyvinyl chloride film, and polycarbonate film can be used as a base film. As the base film, a material that does not melt or soften in a drying zone of a paper machine is used. However, it is preferable that the base film has a property that does not have tackiness at a temperature of a drying zone of 90 to 110 ° C. For this reason, a heat-resistant film such as a polyester film can be preferably used. The film may be subjected to various treatments as long as the object of the present invention is not impaired. For example, a corona discharge treatment or a primer treatment for improving the wetting index, a hologram emboss treatment by applying a transparent resin, or the like is performed. Various films as raw materials usually have a thickness of 8 μm to 25 μm.

In the thread according to the first embodiment shown in FIG. 6, the base film a may be transparent or opaque. However, in the thread according to the second embodiment shown in FIG. Since it is necessary to make the metal deposition layer b and the printing layer c visible through the film a, it is necessary to use a transparent base film.

As a method for forming micro-characters or micro-images comprising the metal-deposited layer b on the base film a, a paster processing method can be preferably used. The paster processing method itself is a well-known method.For example, characters and images are printed with an alkali-resistant ink on a vapor-deposited surface of a polyester film on which metal aluminum is vacuum-deposited, and then the film is immersed in an aqueous sodium hydroxide solution. A typical example is to dissolve the exposed aluminum deposition layer other than the printed portion, and then to wash the film with water to remove the aluminum hydroxide, and then to dry the film (Japanese Patent Application Laid-Open No. Sho 6 (1988)).
No. 3-216795). In this way, the printed portion and the lower metal-deposited portion synchronized with the printed portion remain on the film, and the other portions expose the film.

In manufacturing the thread according to the first embodiment shown in FIG. 6, first, a metal deposition layer b is formed on the entire surface of the base film a using a vacuum deposition machine or a sputtering device. As the metal vapor deposition layer b, metal aluminum vapor deposition is preferable because it is easy to form and easily dissolves in alkali. The thickness of the metal deposition layer b is usually from 250 to 800 angstroms.

Next, a printing layer c is formed by printing micro-characters of normal characters and / or micro-images of normal images on the metal deposition layer b using a transparent ink having alkali resistance. The micro-characters and micro-images at this time may be formed by applying ink to portions (black portions) that become characters or images as shown in FIG.
Ink may be applied to a portion (black portion) other than a portion that becomes a character or an image, such as 0, to form a hollow character or image.

In the present invention, it is necessary to add a dye or pigment which develops color by irradiation with ultraviolet light to the transparent ink. In addition, a coloring agent that looks colored under white light may be appropriately added to the ink as needed.

After forming the print layer c with the transparent ink, the film is immersed in an aqueous sodium hydroxide solution to form the print layer c.
Dissolve the metal deposition layer where there is no. Next, the film is taken out from the aqueous sodium hydroxide solution, washed with water to remove sodium hydroxide remaining on the surface, and then dried. Thereby, on the surface of the base film a,
A micro-character of a normal character and / or a micro-image of a normal image composed of the metal deposition layer b and the printing layer c of the transparent ink thereon is formed. In this specification, the term “micro-characters and / or micro-images made of a metal-deposited layer” is used to include hollow characters and images formed by removing the metal-deposited layer as shown in FIG. .

Further, a heat-sensitive adhesive layer d which melts or softens at the temperature of the drying zone of the paper machine is formed on the back surface of the base film a. The heat-sensitive adhesive layer d is made of a known heat-sensitive adhesive such as an ionomer resin, a polyester resin, a polyvinyl acetate resin, a polyvinyl chloride resin, a polyacrylate resin, and an ethylene-vinyl acetate copolymer resin. The agent can be formed by applying a water-based or solvent-based paint and applying it to the back surface of various films as a raw material using a conventional coating machine such as an air knife coater or a gravure coater. The coating amount is usually 0.1 to 10 g / m ²
And All of these heat-sensitive adhesives are transparent to the extent that they can transmit ultraviolet light, but a coloring agent may be added as needed as long as the transparency is not impaired.

If necessary, micro-characters and / or
Alternatively, a heat-resistant transparent resin coating layer can be applied as a protective layer on the surface of the base film so as to cover the top of the micro image.

In this manner, the raw material film on which the front and rear surfaces are subjected to various processes to form the micro-characters and / or micro-images composed of the metal-deposited layer b and the printed layer c and the heat-sensitive adhesive layer d is formed. Is usually slit into a narrow width of 0.3 to several mm using a microslitter to obtain a thread used in the present invention. At this time, if the micro-characters and / or micro-images are slit so as to be located exactly at the center in the width direction, the production requires a very high-level technique, so that the anti-counterfeiting effect is further enhanced.

The thread according to the first embodiment having the configuration shown in FIG. 6 is used by inserting it into paper so that the surface (front surface) on which the heat-sensitive adhesive is not applied is exposed at the window opening. As a result, when viewed from the front side of the sheet (the side on which the window is formed), macro characters consisting of only regular characters and / or micro images consisting of only regular images can be seen. At this time, when the printing layer c is formed using an uncolored transparent ink, the characters and images appear to shine in the metallic gloss color of the metal-deposited layer b (for example, silver in the case of an aluminum-deposited layer), and yellow. If the printing layer c is formed using a transparent ink colored
The metal glossy color of the metal deposition layer b and the yellow color of the printing layer c overlap, so that gold characters and images can be seen. In addition, when the thread is irradiated with ultraviolet light, it can be seen that the side where the dye or pigment that develops color with the ultraviolet light added to the transparent ink appears to be colored is the thread surface. Even when the surface on which the heat-sensitive adhesive layer d is provided (the back surface of the thread) is irradiated with ultraviolet light, the ultraviolet light is blocked by the metal vapor-deposited layer b which is substantially a light-impermeable layer. It does not look colored.

To manufacture the thread according to the second embodiment shown in FIG. 7, a metal-deposited layer b is formed on the back surface of the transparent base film a, and only the reverse characters are formed on the metal-deposited layer b. Forming a printing layer c by printing micro-characters consisting of the following and / or micro-images consisting only of the reverse image with ink, and a transparent heat-sensitive adhesive on the back surface of the base film so as to cover the printing layer c Except for forming the layer d, the thread can be manufactured in the same manner as the thread manufacturing method of the first embodiment.

The thread having the configuration shown in FIG. 7 is used by inserting it into a sheet so that the surface of the base film a (the surface of the thread) is exposed at the window opening. In this case, when viewed from the front side of the paper, the reverse micro-characters and / or the reverse micro-images composed of the metal deposition layer b and the print layer c are converted into normal characters and / or normal images through the transparent base film a. Will be visible. At this time, when an uncolored transparent base film is used, characters and images appear to shine in the metallic gloss color of the metal-deposited layer b (for example, silver in the case of an aluminum-deposited layer), and the yellow-colored transparent When the base film is used, the metallic gloss color of the metal deposition layer b and the yellow color of the transparent film a overlap, so that gold characters and images can be seen. Further, when ultraviolet rays are irradiated from the surface side of the thread, since the ultraviolet rays are blocked by the metal vapor deposition layer b which is substantially a light impermeable layer, a dye or pigment which is colored by the ultraviolet rays added to the ink of the print layer c is formed. Colors are not visible.
On the other hand, when the surface on which the transparent heat-sensitive adhesive layer d is provided (the back surface of the thread) is irradiated with ultraviolet rays, dyes and pigments that are colored by ultraviolet rays in the ink of the printing layer c appear to be colored through the transparent heat-sensitive adhesive layer. It turns out that it is a thread back. In the configuration of FIG. 7, the ink for printing the print layer c may be transparent or opaque.

As described above, since the front and back of the thread can be easily determined by the irradiation of ultraviolet rays, it is possible to reliably and quickly identify whether or not the front and back of the thread are correctly inserted in the paper making process. That is, after the thread is inserted in the middle of papermaking, by irradiating the wet paper with ultraviolet rays using, for example, a black light to detect the presence or absence of color development, it is easy to determine whether the front and back of the thread are correctly inserted. Can be determined. This makes it possible to minimize the generation of waste paper. The determination of the color of the thread can be automatically performed by visual observation, imaging using a CCD, or the like. When the color is automatically detected, an alarm can be issued at the same time.

As a result of the judgment, if the front and back of the thread are not correctly inserted into the sheet, it is necessary to immediately reverse the thread insertion state. As a method of inverting the thread insertion state, a manual method in which a thread is cut at a thread insertion point, and then the thread is inverted and inserted again, or a method in which a thread insertion device is provided with a thread inversion function and mechanically performed is considered. Can be In the case of mechanically inverting the thread, the thread can be automatically inverted by linking it with the determination result of the coloring of the thread.

In the above description, forgery prevention paper containing a window opening thread has been mainly described as an example. However, the present invention has no window opening portion in the paper, and the thread is inserted inside the paper, and the paper is placed on the paper surface. The present invention can also be applied to a forgery prevention sheet containing a thread that is not exposed. Such a type of anti-counterfeit paper in which the thread is not exposed is used, for example, for perforating a part of a ticket or an admission ticket and for tearing off a part of the ticket along the perforation. There are cases. In this case, if the thread is not coated with the heat-sensitive adhesive, the thread may be pulled out of the paper without being cut at the perforation when a part of the ticket is torn off. Accordingly, even for a forgery prevention sheet containing a thread in which the thread is not exposed, the forgery prevention sheet of the present invention in which a thread having a heat-sensitive adhesive layer is inserted can be preferably used.

Further, even when the threaded paper of a type in which the thread is not exposed is formed, the wet paper after the thread is inserted is irradiated with ultraviolet light or transmitted therethrough to observe the coloring of the printed layer of the thread, so that the front and back of the thread can be formed. This makes it possible to correctly control the state of insertion of the thread into the sheet.

Next, an example of manufacturing a thread used in the present invention will be described in more detail. The coating amount and the coating thickness in these production examples all mean values after drying.

[Production Example of Thread with Micro-Characters Appearing as Silver (See FIG. 6)] Metal aluminum is coated on the entire surface of a polyester film a having a thickness of 12 μm by 400 to 50.
After forming an aluminum vapor-deposited layer b by 0 angstrom vapor deposition, a two-part curable acrylic resin containing a 0.5% by weight of a thiophene-based fluorescent dye added on the aluminum vapor-deposited layer b is used. Using a transparent ink, a printing layer c of micro-characters (see FIG. 9) composed of regular characters was formed using a gravure printing machine. The size of the micro characters was 1 mm, the distance between characters was 1 mm, and the distance between character strings was 2 mm. Next, the film is immersed in an aqueous sodium hydroxide solution to dissolve the aluminum deposited layer other than the portion where the print layer c is formed, and then the film is taken out of the aqueous sodium hydroxide solution, and the sodium hydroxide on the film surface is removed by washing with water. And then dried. Further, on the back surface of the polyester film a, a heat-sensitive adhesive was applied by about 5 μm to form a heat-sensitive adhesive layer d. The string was then slit at the center of the string using a microslitter to produce a thread in which the string was centered. The thread was wound on a bobbin.

[Production Example of Thread with Gold Hollow Micro Letters (See FIG. 6)] A yellow ink was added to the transparent ink. 6 was manufactured in the same manner as in the above-described example of manufacturing a thread with micro-characters that appeared to be silver, except that ink was printed on portions other than the above, and ink was not printed only on character portions. In this thread, the silver color of the aluminum vapor-deposited layer b can be seen through the yellow color of the transparent ink of the print layer c, so that it can be seen as a gold hollow micro-character.

[Production Example of Hologram Thread with Micro-Characters (See FIG. 8)] A transparent thermoplastic resin is applied to a thickness of about 2 μm on the back surface of a transparent polyester film a having a thickness of 12 μm to form a thermoplastic resin coating layer e. After that, a hologram pattern f was hot-embossed thereon. On the hologram pattern f thus obtained, an aluminum vapor deposition layer b was formed. Next, on the aluminum vapor-deposited layer b, micro-characters composed of inverted characters were printed using an alkali-resistant transparent ink to form a print layer c. Subsequent operations were performed in the same manner as in the above-described production example of the thread with micro-characters having a silver color, thereby forming micro-characters of inverted characters composed of the aluminum vapor-deposited layer b synchronized with the print layer c. Next, a transparent heat-sensitive adhesive was applied so as to cover the inverted characters to form a heat-sensitive adhesive layer d, thereby producing a thread. The thread of this configuration is a polyester film a
When viewed from the surface (thread surface) side, the normal micro-characters can be visually recognized as a hologram pattern through the transparent polyester film a and the transparent thermoplastic resin coating layer e.

[0048]

According to the forgery prevention paper of the present invention as described above, the following remarkable effects can be obtained. 1) By judging whether or not the print layer of the thread appears to be colored when the thread is irradiated with ultraviolet rays, the front and back surfaces of the thread can be easily identified. As a result, it is possible to quickly detect whether or not the thread has been correctly inserted during papermaking, to immediately determine the thread insertion state when a thread is inserted during papermaking, and to immediately determine the thread insertion state when incorrect. Can be reversed to return to normal. Therefore, it is possible to significantly increase the production yield of the forgery prevention paper in which the thread is correctly inserted.

2) Since the heat-sensitive adhesive was applied to only one side of the thread (the back of the thread), the thread insertion during papermaking was controlled so that the non-coating side of the heat-sensitive adhesive (the surface of the thread) was exposed at the window opening of the paper. By doing so, these devices will not be contaminated with the heat-sensitive adhesive even if they come into contact with the cylinder dryer, canvas, touch roll, etc. in the drying zone. Furthermore, not only can the cost be reduced compared to a conventional thread coated with a heat-sensitive adhesive on both sides, but there is no special equipment required for the production, and the advantage that a normal coating machine can be used. There is.

3) When viewed from the front side of the sheet, micro-characters of only regular characters and / or micro-images of only regular images are visible on the thread, so that they can be read without discomfort. In order to make only such a normal character and / or a normal image visible, when inserting a thread at the time of paper making, it is necessary to use a thread capable of distinguishing the front and back surfaces.
For that purpose, advanced technology is required, so that the anti-counterfeiting effect is dramatically improved.

4) When the paper is irradiated with ultraviolet light, the printed layer of the thread appears to be colored, so that the authenticity can be easily determined. Also, when looking through the paper into which the thread using the transparent base film is inserted, light does not pass through the metal evaporation layer of the thread, and light passes through the other parts,
It is visually recognized as a kind of plow, and the forgery prevention effect is further enhanced.

5) Since the metallic gloss color of the metal deposition layer can be seen from the front side of the paper, the design is enhanced, and when this is copied by a copying machine, the metallic gloss color cannot be copied, so that the forgery prevention effect is enhanced.

The anti-counterfeit paper obtained according to the present invention by utilizing the above characteristics can be suitably used for bills, checks, stock certificates, bonds, gift certificates, cards, confidential documents, passports, identification cards and the like.

[Brief description of the drawings]

FIG. 1 is a top view of an example of a gift certificate using the forgery prevention paper of the present invention.

FIG. 2 is an enlarged sectional view of a window opening portion of FIG.

FIG. 3 is an explanatory view showing an example of a two-tank-type round-mesh paper machine that can be preferably used for producing the anti-counterfeit paper of the present invention.

FIG. 4 is a partial explanatory view showing a state in which a mold for forming a window opening is attached to the upper net of the net cylinder used in the net paper machine shown in FIG. 3;

FIG. 5 is an explanatory view showing another example of a papermaking apparatus that can be preferably used for producing the forgery prevention paper of the present invention.

FIG. 6 is a sectional view showing a first embodiment of a thread used in the present invention.

FIG. 7 is a sectional view showing a second embodiment of a thread used in the present invention.

FIG. 8 is a sectional view showing one embodiment of a second embodiment of a thread used in the present invention.

FIG. 9 is an explanatory diagram showing an example of micro-characters composed of regular characters formed in a thread in the present invention.

FIG. 10 is an explanatory diagram illustrating an example of a hollow micro character formed of a normal character formed in a thread according to the present invention.

FIG. 11 is an explanatory diagram showing an example of a micro character in which a normal character and a reverse character are mixed in a conventional thread.

[Explanation of symbols]

 1: windowed portion 2: outermost paper layer 3: paper layer in contact with the outermost layer 4: thread 5: non-windowed portion a: base film b: metallized layer c: printing layer d: heat-sensitive adhesive layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-243139 (JP, A) JP-A-10-226996 (JP, A) Registered utility model 3028886 (JP, U) Registered utility model 3030029 (JP, A U) Utility model registration 3034283 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (4)

(57) [Claims] 1. In a forgery prevention paper in which a thread is inserted in the flow direction of the paper, the thread comprises a film serving as a base, and micro-characters and / or micro-characters consisting of a metal deposition layer formed on the surface of the film and consisting of only regular characters. Or a micro image of only a positive image, a printing layer of a transparent ink formed on the metal deposition layer, and a heat-sensitive adhesive layer formed on the back surface of the film, and the ink forming the printing layer Is added with a dye or pigment that develops color when irradiated with ultraviolet rays, and the thread is inserted into the paper so that microscopic characters of normal characters and / or microimages of a normal image can be seen when viewed from the front side of the paper. Anti-counterfeit paper characterized by the following. 2. In the forgery prevention paper, in which a thread is inserted in the flow direction of the paper, the thread is formed of a transparent film serving as a base, and micro-characters consisting of only inverted characters consisting of a metal vapor-deposited layer formed on the back surface of the film. And / or a micro image of only a reverse image, a printing layer of ink formed on the metal deposition layer, and a transparent heat-sensitive adhesive layer formed on the back surface of the film so as to cover the printing layer. The ink for forming the printing layer contains a dye or pigment which develops a color when irradiated with ultraviolet light, and when viewed from the front side of the paper, the reverse micro-characters and / or the reverse micro-images are transparent. The false thread characterized in that the thread is inserted into a sheet so that the thread can be seen through a film as a micro character of a normal character and / or a micro image of a normal image. Construction prevention paper. 3. A window opening having a thickness intermittently reduced in a sheet flow direction is formed on a front side of the sheet, and the thread is exposed at the window opening. Or the forgery prevention paper according to 2. 4. A ratio of the length (X) of the window portion in the flow direction of the sheet to the length (Y) of the non-window portion located between the window portions is 3: The forgery-prevention paper according to claim 3, wherein the ratio is set to 1-1: 2.