JP2002187389A - Information concealing sheet and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the defect that characters or the like of a recording area loom large on the surface of a transferred metallic foil, when a scratch layer is formed by transferring the metallic foil, in lieu of an incorporation-type scratch layer. SOLUTION: A low softening point resin layer 3 composed of a synthetic resin is laminated on a base material sheet 2, and a printed pattern layer 4 to be concealed, consisting of a colored resin composition is laminated on the surface of the low softening point resin layer 3 so as to be flush with the low softening point resin layer 3. Thus the printed pattern layer 4 to be concealed is covered and a thin metallic film 5 is laminated. Under the described structure, the defect that the characters or the like of the recording area loom large, is solved. The thin metallic film 5 may be laminated through a transparent resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention conceals information on a sheet or card by laminating and covering a metal foil and, when used, peels off and removes the metal foil to view the information. Possible sheets and cards with hidden information.

[0002]

2. Description of the Related Art Information on a sheet or a card in which a scratch layer is concealed by laminating a scratch layer is passed to a customer at a store or the like, and the customer can remove the scratch layer and confirm hit or miss. Often used as "lots". In addition, when sending a sheet on which a password or ID number (personal identification number) is recorded by mail or other means, it is important to conceal important information, such as preventing it from being seen by others inadvertently. When necessary, simply remove the scratch layer,
Because information can be seen, it is also used for various purposes.

In the above prior art, the scratch layer is formed by a printing method using an ink composition having a high concealing property by kneading a highly concealing powder such as an aluminum powder in a resin binder. For convenience, this type of scratch layer is referred to as a "knead-type scratch layer". However, in practice, on the information recorded, if only the kneading type scratch layer is provided, it may cause trouble, so that it is necessary to laminate layers other than the kneading type scratch layer. .

For example, when information such as characters is printed on paper and a scratch sheet of a kneading type is directly formed on the paper, and the scratching layer of the kneading type is to be rubbed, the scratch sheet is removed. Since a part of the information may be scraped off together with the kneading-type scratch layer, in order to solve this problem, information such as characters is printed and a transparent resin layer is formed. Also, since the kneading type scratch layer is relatively brittle, if it is peeled off due to external force other than the removal operation, careless contact, etc., the function of hiding the information is impaired. A protective layer is laminated on the type of scratch layer.

Therefore, as an attempt to solve the drawbacks of the kneading type scratch layer, JP-A-2000-2000
No. 25374 proposes laminating a metal foil as a scratch layer, and a transparent resin layer and a protective layer must be laminated as in the case of laminating a conventional kneading type scratch layer. The shortcomings have been eliminated. However, since the metal foil has a smooth surface, the metal foil 1
With only a single sheet, slight irregularities such as characters on the recording surface will emerge through the metal foil, so this publication requires that at least two metal foils be used,
Therefore, it is necessary to transfer the metal foil twice or to prepare a transfer sheet capable of transferring two metal foils.

[0006]

In the present invention, when a metal foil is transferred into a scratch layer instead of a kneading type scratch layer, characters or the like on a recording surface are applied to the surface of the transferred metal foil. It is an object of the present invention to eliminate the drawbacks that emerge.

[0007]

Means for Solving the Problems The present inventor prints on a base material that has been subjected to processing such as lamination of various layers to form characters, and on that,
When the transfer was attempted using a transfer sheet capable of transferring the metal layer, some of the applied layers did not show the unevenness of the characters on the metal layer. By forming a resin layer having thermal characteristics below, and then transferring the metal layer, it was found that the transfer of the metal layer was possible without embossing of the characters, and the present invention was reached. did.

According to a first aspect of the present invention, a low softening point resin layer made of a synthetic resin is laminated on a base material sheet, and a printed pattern to be concealed made of a colored resin composition is formed on the surface of the low softening point resin layer. The layer is laminated so that the surface thereof is flush with the low softening point resin layer, covers the print pattern layer to be concealed, and is laminated with a metal thin film, wherein information is concealed. It is about a sheet. According to a second aspect of the present invention, there is provided a laminate in which a printing pattern layer to be concealed made of a colored resin composition is laminated on a low softening point resin layer made of a synthetic resin so that the surface thereof is flush with the low softening point resin layer. But,
In the base sheet, the printed pattern layer to be concealed is layered on the upper side so that the upper side of the base sheet can be seen through, and on the base sheet in an area corresponding to the laminate. The present invention relates to a sheet in which information is hidden, wherein a metal thin film is laminated.
A third invention relates to the information-concealed sheet according to the first or second invention, wherein the base sheet is made of a thermoplastic resin. According to a fourth aspect, in the first aspect, the softening temperature of the low softening resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret. Is related to the concealed sheet. The fifth invention is
In the third invention, the softening temperature of the low softening resin layer is:
The softening temperature of the colored resin composition constituting the print pattern layer to be concealed, and the softening temperature of the thermoplastic resin constituting the base sheet, characterized in that the information hidden sheet Things. In a sixth aspect of the present invention, a low softening point resin layer made of a synthetic resin and a print pattern layer to be kept secret made of a colored resin composition are formed on the base sheet, and the low softening point resin layer side is the base sheet side. By laminating, by laminating a metal thin film on the print pattern layer to be concealed by heating and pressing, the print pattern layer to be concealed is embedded in the low softening point resin layer, The present invention relates to a method for manufacturing a sheet in which information is hidden. A seventh invention provides a laminate in which a concealed print pattern layer made of a colored resin composition is laminated on a low softening point resin layer made of a synthetic resin, in a base sheet, from the top surface of the base sheet. See through, and laminated so that the print pattern layer side to be concealed is on the upper side, then, on the base sheet in an area corresponding to the print pattern layer to be concealed,
By laminating metal thin films by heating and pressing,
The present invention relates to a method for producing a sheet in which information is concealed, wherein the print pattern layer to be concealed is embedded in the low softening point resin layer. An eighth invention relates to the method for producing a sheet in which information is concealed according to the sixth or seventh invention, wherein a sheet made of a thermoplastic resin is used as the base sheet. Ninth
The invention of the sixth or seventh invention is characterized in that the softening temperature of the low softening point resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret. And a method for manufacturing a sheet in which information is hidden. In a tenth aspect, in the seventh aspect,
The softening temperature of the low softening point resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be concealed, and the softening temperature of the thermoplastic resin constituting the base sheet. The present invention relates to a method for manufacturing a sheet in which information is concealed.

[0009]

FIG. 1 is a diagram showing a basic structure of a sheet in which information is hidden according to the present invention. FIG. 1 (a)
As shown in a plan view, a sheet 1 in which information of the present invention is concealed has a low softening point resin layer 3 laminated on a part of a base sheet 2 such as paper or plastic, and has a low softening point. On the resin layer 3, a print pattern layer 4 to be concealed, which is indicated by characters such as “abc” in the figure, is laminated, and on the low softening point resin layer 3 including the print pattern layer 3 to be concealed, The metal thin film 5 is laminated. In FIG. 1A, the left side of the metal thin film 5 is removed so that the lower print pattern layer 4 and the low softening point resin layer 3 to be concealed are drawn so as to be visible. It is laminated so as to cover at least the entire print pattern layer 4 to be kept secret.

As shown in the cross-sectional view of FIG. 1B, the above-mentioned sheet 1 in which information is concealed has a print pattern layer 4 to be concealed and a print pattern layer to be concealed with the upper surface of the low softening point resin layer 3. The pattern layers 4 are stacked so as to be flush with the upper surface.

The base sheet 2 may be a thin film of paper, plastic, or metal (in the case of metal, a foil), a sheet, or a plate, each alone or in any combination. Can be used. The selection is made in consideration of necessary rigidity, flexibility, adhesiveness at the time of processing, printability, and the like depending on the application. When forming a convex character by embossing, a character having embossing suitability is selected and used.

[0012] The sheet 1 of the present invention in which information is concealed is
As shown in FIG. 1, since the plastic card may be formatted, a vinyl chloride resin sheet may be used as the base sheet 2 for suitability for processing. However, a polyolefin resin which hardly causes a problem when incinerated, It is also preferable to use a sheet of an embossable amorphous polyethylene terephthalate resin or the like, or a heat-resistant resin in which an amorphous polyethylene terephthalate resin and a polycarbonate resin are blended. When a plastic sheet is used, an opaque color sheet such as white or a transparent sheet may be used in combination.

Other plastics include polyamide resin (nylon resin), cellulose diacetate resin, cellulose triacetate resin, polystyrene resin, polyethylene resin, polypropylene resin, polyester resin (polyethylene terephthalate resin, etc.), polyimide resin, polycarbonate resin, polyolefin. A sheet of a base resin or another resin can also be used. In addition to these, when heat resistance is required, a sheet made of a cured product of a thermosetting resin, for example, a melamine resin,
Sheets such as diallyl phthalate resin, phenol resin, and benzoguanamine resin can also be used.

The sheet 1 of the present invention in which information is hidden is
Mainly, the material or shape of the base sheet 2 is variously changed, or the low softening point resin layer 3, the printed pattern layer 4 of information to be kept secret, and the metal thin film 5 are formed on the base sheet 2. For example, by performing recording by various means in an area other than the area to be used, various applications can be achieved.

The use of paper as the base sheet 2 is suitable for applications such as general documents, certificates, stock certificates, securities, various cash vouchers, gift certificates, and tickets for transportation. The use of plastic as the base sheet 2 is suitable for applications such as credit cards, deposit / saving cards, prepaid cards, identification cards, and driver's licenses.

The base sheet 2 may have a normal print pattern layer in addition to the print pattern layer 4 to be kept secret. Note that the print pattern layer refers to a character, figure, symbol, photograph, or the like formed by printing regardless of whether or not to be concealed, but may further include a simple colored layer. The information possessed by these printed pattern layers is not limited to those that can be grasped at a glance, and may have special meanings that cannot be recognized from a mere appearance, such as by encryption, or may be bar codes or other forms. , May be signalized. In addition, not only the size that is usually visible, but also a very small size, or a printed pattern layer that is not normally visible but can be read by an appropriate means for making it visible may be used.

In addition to forming a printed pattern layer on the base sheet, magnetic recording is performed by forming a magnetic recording layer; information is recorded by embedding an IC module; a metal thin film is formed; Optical recording, embossing, embossing, coloring convex parts to form embossed characters, laminating sign panels, signing the holder, pasting pictures, stickers to indicate that they are genuine (especially holograms) Stickers).

The low softening point resin layer 3 is a layer for ensuring the information concealing property in the information concealed sheet 1 of the present invention. Since the low softening point resin layer 3 softens relatively easily by heating, it can be embedded in the low softening point resin layer 3 by pressing the print pattern layer 4 to be concealed. As a result, The printed pattern layer 4 to be kept secret can be prevented from protruding from the low softening point resin layer 3.

The softening point (meaning of the softening temperature) of the resin constituting the low softening point resin layer 3 is preferably sufficiently higher than room temperature for use of the sheet 1 in which information is concealed. It is preferable that the temperature is relatively low so that the sheet 1 in which the information is hidden is not damaged by heat, specifically, 120 ° C. or less, more preferably 100 ° C. or less. The softening point of the resin constituting the low softening point resin layer 3 is preferably as low as possible. However, if the softening point is excessively low, the environmental temperature at the time of using the sheet 1 in which information is concealed may increase, or a careless approach to a heat source may occur. By doing so, the sheet 1 where the information is hidden
In particular, since there is a possibility that a certain portion of the low softening point resin layer 3 may be deformed or peeled off, the softening point of the resin constituting the low softening point resin layer 3 is preferably 30 ° C. or higher, more preferably. Is 50 ° C. or higher.

The resin constituting the low softening point resin layer 3 has a softening point in the above range and is selected in consideration of the adhesiveness to the base sheet 2, the printed pattern layer 4, and the metal thin film 5. However, in addition, by blending plastics with different softening points and blending plasticizers with resins with high softening points,
The softening point can be adjusted.

The material constituting the base sheet 2 is as described above. When the base sheet 2 is made of a material having a softening point, specifically, a thermoplastic resin is used. In the case where the base material 2 is mainly constituted, the thermoplastic resin of the material forming the base material sheet 2 is selected such that the softening point of the base material sheet 2 is higher than the softening point of the low softening point resin layer 3. By doing so, it is possible to eliminate the thermal effect on the base sheet 2 and to soften the low softening point resin layer 3.

If the softening point of the base sheet 2 is lower than the softening point of the low softening point resin layer 3, when the printing pattern layer 4 to be concealed is heated and pressed, the low softening point resin layer 3 is hardened. Is not deformed, the underlying base sheet 2 is compressed and deformed, and as a result, the print pattern layer 4 to be kept secret remains in a state of protruding from the low softening point resin layer 3. This is because fear is great.

The position where the low softening point resin layer 3 is laminated is not limited to a part of the center of the base sheet 2 as shown in the figure, but may be laminated on the entire surface of the base sheet 2. Further, the low softening point resin layer 3 may be laminated not only on the upper surface of the base sheet 2 as shown in the drawing, but only on the lower surface, or may be laminated on both the upper surface and the lower surface. Low softening point resin layer 3
Is formed according to the size of the print pattern layer 4 to be concealed, which is laminated thereon, and the print pattern layer 4 to be concealed is preferably laminated at least on the low softening point resin layer 3. . The low softening point resin layer 3 may be laminated on the base sheet as shown in FIG. 1 (b), or may be laminated as shown in FIG. 1 (c). Part or all of the layer 3 may be embedded in the base sheet 2 or the like.

The low softening point resin layer 3 is formed by using a resin solution obtained by dissolving the resin constituting the low softening point resin layer 3 with a solvent, using a known coating method or a known printing method. This can be performed by laminating on the sheet 2.
Alternatively, the formation of the low softening point resin layer 3 can also be performed by transferring onto the base material sheet 2 using a transfer sheet in which such layers are releasably laminated. The low softening point resin layer 3 may be colored as required, or a normal printing pattern layer other than the printing pattern layer 4 to be kept secret may be laminated on the low softening point resin. You may. The thickness of the low softening point resin layer 3 is preferably at least the same as or greater than the thickness of the print pattern layer 4 to be kept secret,
It is at least 0.5 μm, more preferably at least 1.0 μm.

The print pattern layer 4 to be concealed is laminated on the low softening point resin layer 3, covered with a metal thin film 5 described later, and concealed. As described in the description of the related art, the information to be kept in the print pattern layer 4 to be concealed includes, for example, a display of a lottery, a password and an ID number (a number for confirming an individual), and the individual of the party concerned. What kind of information should not be disclosed as information, or if it is disclosed, the parties could suffer unforeseen damage, or should not be viewed by anyone other than those who have legitimate rights It may be information.

The print pattern layer 4 to be concealed is normally visible if it is formed and not covered with the metal thin film 5, but is formed by an invisible method. It may be visible by emitting fluorescent light by ultraviolet irradiation. The print pattern layer 4 to be concealed may be a character, a graphic, or a symbol, or a character, a picture, a picture, a barcode, an OCR character, or the like, which overlaps them. It is preferable that the thickness of the print pattern layer 4 to be kept secret does not exceed the thickness of the low softening point resin layer 3.

The printing pattern layer 4 to be concealed is formed on the low softening point resin layer 3 by a known printing method, and a transfer sheet in which the printing pattern layer 4 to be concealed is releasably laminated. It may be carried out by transferring it onto the low softening point resin layer 3. The print pattern layer 4 to be kept secret may be output by various printers based on data stored in the memory of the computer. In the case where the print pattern layer 4 to be kept secret and the low softening point resin layer 3 are both laminated by transfer, a transfer sheet in which both layers are adhered to each other and laminated as a whole so as to be peelable. Is prepared and is transferred onto the base sheet 2 using the transfer sheet, so that both the low softening point resin layer 3 and the print pattern layer 4 to be kept secret can be transferred by one transfer.

The metal thin film 5 covers and conceals the underlying printed pattern layer 4 to be concealed. At least, it is sufficient that the resin layer 3 is laminated only on the print pattern layer 4 to be concealed. However, when the low softening point resin layer 3 is laminated on a part of the base sheet 2, in order to complete the concealment, It is preferable to cover the entire area of the low softening point resin layer 3 and its periphery. This is because as the metal thin film 5 is larger, the position where information is recorded becomes more difficult to understand. Aluminum is preferable as a material constituting the metal thin film 5 from an economic viewpoint, but metals other than aluminum, such as gold, silver, copper, zinc, tin, nickel, and chromium, can be used.

The metal thin film 5 made of these materials has a thickness of preferably 30 nm or more when formed in a vapor phase such as vapor deposition because the lower layer must be concealed, and the upper limit is particularly limited from the viewpoint of concealment. However, it is 80 nm or less, more preferably 50 nm or less. When the metal thin film 5 is made of a metal foil, it is possible to handle the metal foil alone.
If the thickness is about 5 μm or more, it can be used. Although there is no particular upper limit, it is about 30 μm in consideration of economy.

Since the metal thin film 5 alone does not have adhesiveness, when laminating the metal thin film 5 with the lower layer, either the lower surface of the metal thin film 5 or the upper surface of the lower layer, or both, is formed. Apply an adhesive layer and laminate via the adhesive layer. If the lower layer of the metal thin film 5 has adhesiveness, the adhesive layer may be omitted. The lamination of the metal thin films 5 may be performed using a transfer sheet on which the metal thin films 5 are releasably laminated. When the metal thin film 5 is stacked, the lower layer of the metal thin film 5 can be stacked by applying heat and pressure. However, by controlling the heating temperature, the lower layer of the metal thin film 5 or the lower layer can be kept secret. The printed pattern layer 4 to be embedded can be embedded in the low softening point resin layer 3.

The sheet 1 of the present invention in which information is concealed is
As described above, in addition to the basic structure in which the base sheet 2, the low softening point resin layer 3, the printed pattern layer 4, and the metal thin film 5 are sequentially stacked in contact with each other,
Although there is not much ideological difference, the following modified structure may be caused due to the actual structure of the base sheet 2.

FIGS. 2A and 2B show a basic structure and a modified structure. 2A and 2B, the base sheet 2 has a structure in which a total of four layers of the oversheet 2a, the core sheets 2b and 2b ', and the oversheet 2a' are sequentially laminated from the top. is there. The three layers of the low softening point resin layer 3, the printing pattern layer 4, and the metal thin film 5 are laminated on the base sheet 2 having such a four-layer structure, and only the metal thin film 5 can be peeled off after the lamination. There are two ways to do this.

One is, as shown in FIG. 2 (a), a low softening point resin layer 3, a printed pattern layer 4, and a metal thin film 5 laminated in this order on a base sheet 2 having a four-layer structure. It is.
This structure has a low softening point resin layer 3, a printed pattern layer 4,
Alternatively, it can be manufactured by one transfer using a transfer sheet in which three layers of the metal thin film 5 are stacked on each other and the three layers are peelably stacked.

The other is, as shown in FIG. 2B, a core sheet 2b and an oversheet 2a of the base sheet 2.
And two layers of the low softening point resin layer 3 and the printing pattern layer 4 are laminated, and on the oversheet 2a, at a position above the low softening point resin layer 3 and the printing pattern layer 4 ,
The metal thin film 5 is laminated. That is, the metal thin film 5
May be laminated via a transparent resin layer. In this structure, the print pattern layer 4 to be kept secret and the low softening point resin layer 3 are provided in this order on the lower surface of the over sheet 2a, or the low softening point resin layer 3 is provided on the upper surface of the core sheet 2b and the over layer is provided. The printed pattern layer 4 is provided on the lower surface of the sheet 2a, or the low softening point resin layer 3 is provided on the upper surface of the core sheet.
And two layers of the printed pattern layer 4 in this order.

Here, the oversheet is a transparent sheet made of plastic, and in the case of a general-purpose plastic card, the thickness is 100 μm, and the core sheet is a white sheet made of plastic and has concealing properties. Has a thickness of 280 μm.

When manufacturing the sheet 1 of the structure shown in FIG. 2 (a) in which information is hidden, as shown in FIG. 3 (a), it is placed on an oversheet 2a (the lower layer is not shown). ,
A laminated body immediately before completion is obtained by laminating the low softening point resin layer 3, the print pattern layer 4 to be concealed, and the metal thin film 5 in an overlapping manner.
In this state, the print pattern layer 4 to be kept secret is laminated on the low softening point resin layer 3 as a convex portion. Base sheet 2
May have a four-layer structure as shown in FIG. Thereafter, the metal thin film 5 on the laminate immediately before completion is heated and pressurized to soften the lower softening point resin layer 3 so that the print pattern layer 4 to be concealed is placed in the softening point resin layer 3. By embedding, the upper surface of the print pattern layer 4 to be concealed is laminated so as to be flush with the upper surface of the low softening point resin layer 3 (FIG. 3B).

As described above, instead of heating and pressurizing the laminated body immediately before completion, the uppermost metal thin film 5 is formed.
Is applied on the low softening point resin layer 3 to which the print pattern layer 4 to be concealed is applied, and at the same time, by heating and pressing, the lower low softening point resin layer 3 is softened and the print pattern layer 4 to be concealed is lowered. It may be embedded in the softening point resin layer 3 so that the upper surface of the print pattern layer 4 to be concealed is stacked on the same plane as the upper surface of the low softening point resin layer 3.

When manufacturing the sheet 1 having the structure shown in FIG. 2B and in which information is hidden, as shown in FIG. 4A, a core sheet 2b (illustration below the core sheet 2b ') is omitted. )) And the oversheet 2a, the core sheet 2b
From the side, the lower softening point resin layer 3 and the print pattern layer 4 to be concealed are laminated, and the upper oversheet 2a on which the low softening point resin layer 3 and the print pattern layer 4 to be concealed are laminated.
A metal thin film 5 is superimposed thereon and temporarily bonded to form a laminate immediately before completion. Also in this state, between the core sheet 2b and the oversheet 2a, the print pattern layer 4 to be kept secret is laminated on the low softening point resin layer 3 as a convex portion. Thereafter, the metal thin film 5 on the laminate immediately before completion is heated and pressurized to soften the lower softening point resin layer 3 so that the print pattern layer 4 to be concealed is placed in the softening point resin layer 3. By embedding, the upper surface of the print pattern layer 4 to be concealed is laminated so as to be flush with the upper surface of the low softening point resin layer 3 (FIG. 4B).

As described above, instead of heating and pressurizing the temporary adhesive just before completion, instead of applying heat and pressure, the lower softening point resin layer to which the printed pattern layer 4 in which the uppermost metal thin film 5 should be kept secret is applied. By applying heat and pressure simultaneously with the application onto the lower layer 3, the lower softening point resin layer 3 as a lower layer is softened, the print pattern layer 4 to be concealed is embedded in the low softening point resin layer 3, and the print pattern layer to be concealed. 4 may be stacked so that the upper surface of the resin layer 4 is flush with the upper surface of the low softening point resin layer 3. Alternatively, the printing pattern layer 4 to be concealed is buried in the low softening point resin layer 3 by sufficiently heating and applying pressure before the topmost metal thin film 5 is applied. Good results can also be obtained by heating and pressing simultaneously with the application of the thin film 5.

When the base sheet 2 is mainly composed of a thermoplastic resin, the base sheet 2 has a softening point higher than the softening point of the low softening point resin layer 3. Although it has been stated that it is preferable to select a thermoplastic resin as a material constituting the material sheet 2, the print pattern layer 4 to be kept secret is described.
Also, it is preferable that the softening point is higher than the softening point of the low softening point resin layer 3. In this way, heating and pressurizing are performed at a temperature intermediate between the two softening points to soften the low softening point resin layer 3 and to conceal the print pattern layer 4 to be concealed when embedding it in the low softening point resin layer 3. It is possible to prevent the printed pattern layer 4 to be deformed or melted.

Further, the ink is printed and cured by using an ink composition containing a curable resin as a binder resin.
The print pattern layer 4 to be concealed is printed using an ink composition using a thermoplastic resin as a binder resin and does not have a softening point as when formed, but has high durability when heated and pressed. By applying heat and pressure, it is easy to embed in the low softening point resin layer 3, which is preferable.

The binder resin made of a general thermoplastic resin constituting the ink composition may have a softening point higher than the softening point of the low softening point resin layer 3 consciously set to a low softening point. In many cases, when designing the ink composition, it is preferable to select a binder resin such that the softening point of the print pattern layer 4 to be kept secret is higher than the softening point of the low softening point resin layer 3 by 10 ° C. or more. In this way, by heating and pressurizing at a temperature intermediate between the two softening points, one of the softening points can be prevented. Although there is no particular upper limit for the softening point of the ink composition, the softening point of the print pattern layer 4 to be concealed, formed using a binder resin selected in the range of a practical thermoplastic resin, is about 150 ° C. It is. In addition, in the print pattern layer 4 to be concealed formed using the ink composition, since there is a difference from the ink composition due to evaporation of the solvent, etc., it is referred to as being formed from the colored resin composition. To be distinguished. It should be noted that some of the print pattern layers 4 which are formed by using a curable resin binder resin and which are to be concealed and which are to be kept secret are not easily softened.

As with the softening point of the print pattern layer 4 to be kept secret, the softening point of the base sheet mainly composed of a thermoplastic resin should be higher by at least 10 ° C. than the softening point of the low softening point resin layer 3. It is preferably about 150 ° C. or less in practical use.

[0044]

(Example 1) Base sheet, low softening point resin layer,
Each layer of the printing layer was laminated in this order as follows to produce a printing sheet. As the base sheet, a biaxially stretched polyethylene terephthalate resin film having a thickness of 188 μm and having a single-sided corona discharge treatment (softening point: 150
° C), and using a low softening point resin layer forming ink composition having the following composition on the corona discharge treated surface, by a silk screen printing method, a dry thickness of 1.0 µm and a softening point of 8
A resin layer having a low softening point of 0 ° C. was formed substantially at the center of the base sheet. The softening point was the temperature at which the value of tan δ = E2 / E1 reached a peak from the elastic modulus E1 and the viscosity E2 obtained by the following measurements. As a measuring device,
Longitudinal vibration type dynamic viscoelasticity measurement device, name: "Rheogel
-E4000 "(manufactured by UBM Corporation)
(1) measurement method; dynamic viscoelasticity measurement (sine wave); (2) measurement mode; temperature dependence; (3) chuck;
(4) Waveform; sine wave, (5) sample; width 5 mm, length 20 mm, (6) measurement conditions; frequency: 10 Hz, temperature range: 30 ° C to 70 ° C, heating rate: 3 ° C / min. ,distorted;
10 μm (automatic control). (Ink composition for forming softening point resin layer)-30 parts of vinyl chloride / vinyl acetate copolymer-based resin-25 parts of cyclohexanone-20 parts of toluene In addition, "parts" including those hereinafter are based on mass.

A character is printed on the formed low softening point resin layer using an ultraviolet-curable offset printing ink,
The printed layer was formed by curing by irradiation with ultraviolet rays. The thickness of the coating film of the printing layer is 1 μm, and the softening point of the coating film is 120 μm.
° C.

A transfer sheet for transferring a metal thin film on the print layer was prepared. The support sheet has a thickness of 16μ.
A biaxially stretched polyethylene terephthalate resin film having a thickness of 0.5 m was formed by a gravure reverse coating method using a coating liquid for forming a releasable resin layer having the following composition. Then, an aluminum thin film having a thickness of 500 mm is formed on the release resin layer by a vacuum evaporation method, and a gravure reverse coating method is further performed on the aluminum thin film using a coating liquid for forming an adhesive layer having the following composition. As a result, an adhesive layer having a thickness of 1 μm when dried was formed to obtain an aluminum thin film transfer sheet.

(Coating liquid for forming a release resin layer) 5 parts of melamine acrylate resin 1 part of cellulose acetate resin 0.05 parts of paratoluenesulfonic acid 25 parts of methyl alcohol 45 parts of ethyl alcohol (adhesive (Coating liquid for layer formation) ・ Vinyl chloride / vinyl acetate copolymer resin 20 parts ・ Acrylic resin 10 parts ・ Ethyl acetate 20 parts ・ Toluene 50 parts

The aluminum thin film transfer sheet also prepared as described above is overlapped on the low softening point resin layer on which the printing layer is formed, on the printing sheet prepared as described above, so that the adhesive layer side of the aluminum thin film transfer sheet also prepared as described above. Using a hot press, heating and pressurizing for 1 second at a hot platen temperature of 150 ° C. and a pressure of 50 kg / cm ² , the aluminum thin film is transferred onto the printing pattern layer, and the printing layer is made of a metal thin film. Was obtained.

Example 2 A film having a thickness of 280
Two types of white polyethylene terephthalate resin film (softening point: 90 ° C., hereinafter referred to as white PET film) and transparent polyethylene terephthalate resin film (softening point: 90 ° C., hereinafter referred to as transparent PET film) were prepared. . First, a low softening point resin layer (with a softening point of 80) was formed on a white PET film by using the same material and means as those applied to the base sheet in Example 1.
° C) and a printing layer (softening point is 120 ° C).

On the side of the white PET film on which the low softening point resin layer and the printing layer were laminated, one transparent PET film was placed, and on the side where the low softening point resin layer and the printing layer were not laminated, the white PET film was placed. And a transparent PET film are stacked one by one in order, and the whole of the stacked ones is heated using a hot press at a hot platen temperature of 150 ° C. and a pressure of 50 kg / cm.
^Under the conditions of ² , heating and pressurizing were performed for 10 seconds to thermally fuse each other to form a laminate.

The transparent PET film on the side of the laminate produced as described above where the printed layer is visible through the transparent PET film (when viewed from the opposite side, the printed layer is not visible due to the opacity of the white PET film). On the upper side, there is a resin layer having a low softening point, on which a printing layer is laminated, on the upper side so that the adhesive layer side of the same aluminum thin film transfer sheet prepared in Example 1 is in contact with the upper layer. Heating and pressurizing for 1 second under the conditions of a board temperature of 150 ° C. and a pressure of 50 kg / cm ² , the aluminum thin film was transferred above the printing layer, and a laminate in which the printing layer was hidden by a metal thin film was obtained. Was.

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the formation of the low softening point resin layer was omitted.

Comparative Example 2 Example 1 was repeated except that a low softening point resin layer was formed after forming a printing layer on a base sheet.
Was performed in the same manner as described above.

(Comparative Example 3) The same operation as in Example 2 was performed except that the formation of the low softening point resin layer was omitted.

(Comparative Example 4) A printing layer was formed on a white PET film, and then a resin layer having a low softening point was formed.
Performed in the same manner as in Example 2.

(Comparative Examples 5 and 6) Resin layers corresponding to low softening point resin layers were printed using different types of ultraviolet curable offset printing inks, respectively, and cured by irradiation with ultraviolet light to obtain a softening point. However, a resin layer having a low softening point of 90 ° C. (Comparative Example 5) and 100 ° C. (Comparative Example 5) was formed.

With respect to the samples obtained in Examples 1 and 2 and Comparative Examples 1 to 6, it was determined whether or not the presence of the printed layer could be visually recognized by the unevenness of the surface of the metal thin film (concealing property).
The results determined by visual observation are defined as the softening point (T1) of the printed layer,
The results are shown in Table 1 together with the softening point (T2) of the low softening point resin layer and the softening point (T3) of the base sheet. The removal of the metal thin film could be performed without any problem in any of the samples.

[0058]

[Table 1]

[0059]

According to the first aspect of the present invention, a printed pattern layer to be kept secret is formed on the low softening point resin layer so that its surface is flush with the low softening point resin layer, and a metal thin film is formed thereon. Is laminated, so that the printed pattern layer cannot be seen through the metal thin film, and of course, there is no unevenness due to the presence of the printed pattern layer on the surface of the metal thin film layer. Unless the thin film is removed, it is possible to provide a sheet in which the information of the printed pattern layer cannot be read and the information is concealed. According to the invention of claim 2, the print pattern layer to be kept secret is formed on the low softening point resin layer so that the surface thereof is flush with the low softening point resin layer, and the metal thin film is laminated thereon. As a result, the printed pattern layer is not seen through the metal thin film.
Provide a sheet in which the information of the printed pattern layer cannot be read unless the metal thin film is removed, since the unevenness based on the presence of the printed pattern layer does not occur on the surface of the metal thin film layer. Can be. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or claim 2,
By using a thermoplastic resin for the base sheet, it is possible to provide a sheet that is practical and easy to process at the time of manufacture and has hidden information. According to the invention of claim 4, in addition to the effect of the invention of claim 1, the softening temperature of the low softening point resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret. At the time of manufacture, it is ensured that the printed pattern layer to be concealed in the upper layer is embedded in the softening point resin layer by applying heat and pressure so as not to protrude from the low softening point resin layer. A concealed sheet can be provided. According to the invention of claim 5, in addition to the effect of the invention of claim 3, the softening temperature of the low softening resin layer is the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret, and Because it is lower than any of the softening temperatures of the thermoplastic resin constituting the base sheet,
At the time of manufacturing, the print pattern layer to be concealed in the upper layer is embedded in the softening point resin layer by applying heat and pressure so that it does not protrude from the low softening point resin layer, and the effect on the metal thin film surface is reduced. It is possible to provide a sheet in which information is concealed, which can avoid the influence without affecting the base sheet. According to the invention of claim 6, when laminating the metal thin film, the printing pattern layer to be kept confidential of the low softening point resin layer is heated and pressed to be embedded in the low softening point resin layer. The printed pattern layer cannot be seen through the metal thin film laminated thereon, as well as the presence of the printed pattern layer can be prevented from being seen as a projection on the surface of the upper metal thin film. A method for manufacturing a sheet can be provided. According to the invention of claim 7, when laminating the metal thin film,
The printing pattern layer, which should be kept secret from the low softening point resin layer, is heated and pressurized and embedded in the low softening point resin layer, so that the printing pattern layer can be seen through the thin metal film laminated above the printing pattern layer. Needless to say, it is possible to provide a method for manufacturing a sheet in which information is hidden, which can prevent the presence of the printed pattern layer from being seen as a convex portion on the surface of the metal thin film. According to the invention of claim 8, in addition to the effect of the invention of claim 6 or 7, handling and processing can be easily performed by using a base sheet made of a thermoplastic resin.
A method for manufacturing a sheet in which information is hidden can be provided. According to the ninth aspect of the present invention, in addition to the effects of the sixth or seventh aspect of the present invention, the softening point of the low-softening point resin layer is softening of the colored resin composition constituting the print pattern layer to be kept secret. Since the temperature is lower than the temperature, the printed pattern layer to be concealed can be embedded in the low softening point resin layer so as not to protrude beyond the low softening point resin layer. And a method for manufacturing a sheet. According to the invention of claim 10, in addition to the effect of the invention of claim 7, as the low softening point resin layer, the softening temperature is the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret, and Since the one that is lower than the softening temperature of the thermoplastic resin constituting the base sheet is used, at the time of manufacturing, the print pattern layer to be kept secret is embedded in the low softening point resin layer by applying heat and pressure, By not protruding from the low softening point resin layer, to avoid the effect on the metal thin film surface, can be performed without affecting the base material sheet,
A method for manufacturing a sheet in which information is hidden can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic structure of a sheet in which information is hidden.

FIG. 2 is a cross-sectional view of a sheet in which information is hidden, in which a base sheet is a multilayer.

FIG. 3 is a view showing a method of processing a surface of a base material sheet.

FIG. 4 is a view showing a method for processing into a multi-layer base sheet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Card in which information was hidden 2 Base sheet (2a; oversheet, 2b; core sheet) 3 Low softening point resin layer 4 Printing pattern layer 5 Metal thin film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C005 HA13 HA17 HB12 KA03 KA09 KA11 KA40 4F100 AB01D AK01A AK01B AK01C AK42 AL05C AT00A BA04 BA10A BA10D BA13 EC142 EH012 EH46 EJ172 EJ38 EJ422 J90 HB31B02B90B04B

Claims (10)

[Claims] A low softening point resin layer made of a synthetic resin is laminated on a base sheet, and a printed pattern layer made of a colored resin composition is concealed on the surface of the low softening point resin layer. A sheet in which information is concealed, wherein the sheet is laminated so as to form the same plane as the resin layer having a low softening point, and a metal thin film is laminated so as to cover the print pattern layer to be concealed. 2. A laminated body comprising a low-softening point resin layer made of a synthetic resin and a printing pattern layer made of a colored resin composition to be concealed, the surface of which is stacked on the same plane as the low-softening point resin layer. In the base sheet, the printed pattern layer side to be concealed is laminated so that it can be seen through from the upper surface of the base sheet, and the printed pattern layer side to be concealed is on the upper side, and on the base sheet in an area corresponding to the laminated body , A sheet in which information is hidden, wherein a metal thin film is laminated. 3. The information-concealed sheet according to claim 1, wherein the base sheet is made of a thermoplastic resin. 4. The information according to claim 1, wherein the softening temperature of the low softening resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret. Concealed sheet. 5. The softening temperature of the low softening resin layer is higher than the softening temperature of the coloring resin composition constituting the print pattern layer to be kept secret and the softening temperature of the thermoplastic resin constituting the base sheet. 4. The sheet according to claim 3, wherein the information is low. 6. A low-softening point resin layer made of a synthetic resin and a print pattern layer to be concealed made of a colored resin composition are formed on a base sheet so that the low-softening point resin layer side is the base sheet side. Laminating and then laminating a metal thin film on the print pattern layer to be concealed by heating and pressing, thereby embedding the print pattern layer to be concealed in the low softening point resin layer. A method for producing a sheet in which is hidden. 7. A laminate formed by laminating a print pattern layer to be concealed made of a colored resin composition on a low softening point resin layer made of a synthetic resin is seen through a top surface of the base sheet in a base sheet. Possible, and laminated so that the print pattern layer side to be concealed is on the upper side, then, on the base sheet in an area corresponding to the print pattern layer to be concealed, by heating and pressing a metal thin film A method for manufacturing a sheet in which information is concealed, wherein the printing pattern layer to be concealed is embedded in the low softening point resin layer by laminating. 8. The method according to claim 6, wherein a sheet made of a thermoplastic resin is used as the base sheet. 9. The softening temperature of the low softening point resin layer is lower than the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret.
A method for producing a sheet in which the described information is hidden. 10. The softening temperature of the resin layer having a low softening point, the softening temperature of the colored resin composition constituting the print pattern layer to be kept secret, and the softening temperature of the thermoplastic resin constituting the base sheet. The method for manufacturing a sheet in which information is concealed according to claim 7, wherein the lower limit is lower than the lower limit.