JPH08146881A - Sheet for hiding - Google Patents

Abstract

PURPOSE: To make adhesion to post cards, etc., similar to heretofore, to make readhesion after peeling infeasible and to reduce a cost by laminating paper subjected to printing for hiding, an adhesive layer, a base film and an adhesive layer in this order. CONSTITUTION: The front surface of a biaxially stretched polypropylene film (OPP) which is the base film 2 is subjected to a corona treatment 3. The side not subjected to the corona treatment is provided with a first adhesive layer 4 and the side subjected to the corona treatment is provided with the second adhesive layer 5. Further, paper 6 is laminated atop the second adhesive layer 5. The rear surface of the paper 6 is subjected to printing 7. Either of the front or rear of the OPP is peeled but peeling arises always on the side not subjected to the corona treatment 3. The printing surface has a hiding property if the sheet for hiding is stuck on the post card, etc., and, therefore, the characters on the post card are not readable at all. If the sheet is peeled, the characters are readable as the first adhesive layer 4 is transparent. Further, readhesion is not possible unless the adhesive layer is heated by an iron, etc., once the adhesive layer is peeled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hiding sheet.

[0002]

2. Description of the Related Art A concealing sheet is a sheet that is attached to conceal information such as characters written under it.
Therefore, it is required that it can be easily attached, that it can be peeled off, that the information below cannot be read, and that it cannot be re-bonded once peeled. There are various applications such as catalogs, postcards, and other documents that need to be kept confidential, and the present invention itself is not limited in its applications, but the following description will be given taking postcards as an example.

Usually, a postcard is the cheapest method of communicating information or contact information to the other party. Therefore, if the amount of information that can be written on the postcard is sufficient, the postcard must be used.
However, since the postcard is readable by anyone and it is completely unknown whether or not it has been read, it is impossible to inform the personal privacy information on the postcard. Therefore, we had to resort to expensive envelopes.

Therefore, recently, a method has been adopted in which a seal is attached to the personal information and the like so that the characters in the lower layer cannot be seen, and the person who receives it peels it off. Further, since it is difficult to re-bond the seal once it has been peeled off, it is possible to easily determine whether or not the information is seen. Of course, it has no effect on the person who views the information by discarding the postcard without thinking about the latter, but this is out of the question here because it is the same with the sealed letter.

In this case, only a thin sticker is attached, and it can be mailed at the postage cost of the postcard.
This seal is the concealing sheet.

Conventionally, this type of seal has been described above.
In order to obtain the effect of (1), the part to be adhered to a postcard or the like is made of a hot melt adhesive so that it can be easily attached by heating, and once peeled, it cannot be adhered without heating. Further, regarding the above, it is performed by adjusting the adhesive force. Finally, the hiding property is secured by using an aluminum sheet.

Therefore, the conventional concealing sheet is a laminated body composed of paper, an adhesive layer, an aluminum sheet, a release treatment layer such as silicon, and an adhesive layer.

[0008]

However, this conventional concealment seal is expensive. This is because an aluminum sheet is used and a release agent such as silicon is used. This concealing sheet itself is meaningless unless it is cheap. That is, if the price is higher than the price of a sealed letter, there is no point in using it. Therefore, in this industry, there has been a demand for a concealing sheet that is as inexpensive as possible and satisfies the above requirements (1) to (3).

[0009]

In view of the above circumstances, the present inventor has completed the concealing sheet of the present invention as a result of earnest research, and the feature thereof is that in the first aspect, In the second mode, the paper, the adhesive layer, and the base film on which the concealment printing is applied are laminated in this order.
The point is that the adhesive layers are laminated in this order.

The base film is a biaxially oriented polypropylene film (OPP) which is transparent and does not melt when thermocompression-bonded, or translucent such as opalescent and matte. 20-40 micrometers is suitable for thickness. The degree of stretching is
It may be about 5 to 8 times. The reason why the biaxially stretched polypropylene film is used is that it is inexpensive and can be adhered or easily peeled.

Peeling occurs on one side of this base film. That is, the base film such as a postcard is peeled off so that the base film is not left on the base material. For that purpose, corona treatment is performed on the side opposite to the base material, that is, the surface side of this base film, or anchor coating treatment is applied thereon. by this,
Since the adhesive strength is significantly different from that on the opposite side, peeling does not occur on both sides and spoils aesthetics. In the corona discharge treatment, high voltage is applied to both sides of the film to generate high voltage corona on both sides of the film to be treated with a gap. As a result, the film to be processed has easy adhesion. This is an ordinary method and is often used when adhering a polyethylene film or polypropylene. Also in the present invention, the usual method may be used.

An adhesive layer (first adhesive layer) is provided on the side of the base film which has not been subjected to corona treatment or the like. This is a heat-sensitive adhesive that melts when heated and adheres to the base film. Of course, when the temperature is lowered, it solidifies and becomes a film again. A heated liquid may be applied to the base film. Basically, the material may be a thermoplastic resin, but the condition is that the melting point is lower than that of polypropylene which is the base film. In addition, the adhesive force to paper or printing surface is also required. Therefore, EVA (vinyl acetate), EEA
Polyethylene mixed with (ethyl acrylate) is suitable. Furthermore, EVA is 10 to 20%, EEA is 7 to
A three-component polyethylene mixed with 20% was more suitable. Of course, there is no problem even if additives are added other than this.

An adhesive layer is also provided on the side of the base film that has been subjected to anchor treatment or the like. This is also the first
It may be the same as the adhesive layer. However, since it does not need to be peeled off on the upper surface side of the base film and there is no restriction that it cannot be re-adhered, ordinary adhesives (those that do not need to be heated. For example, solvent type or reactive type) May be used. The thickness of the adhesive layer is usually preferably about 15 to 30 μm for both the first adhesive layer and the second adhesive layer.

Finally, paper is attached to the outermost surface opposite to the base material. This paper is printed in order to improve the concealing property. Any kind of printing can be used, but it is premised that the letters below cannot be seen. Therefore, the presence or absence of patterns,
It doesn't matter what color, one color or multiple colors. It is desirable to select an ink or pigment having excellent hiding properties. Usually, solid black printing is inexpensive and excellent in effect. Printing is usually performed on the back side of the paper. This is to keep the aesthetic appearance by making the solid printing invisible. Of course, a pattern or the like may be applied to the front side. As paper, 45g of coated paper or fine paper
Those of 70 g / m ² are preferable.

Next, as another aspect of the present invention, the above-mentioned printing on paper may be applied to the base film. In this case, paper is further attached to the printed base film. Of course, it is desirable to print after corona treatment. Regardless of where the printing is performed, as long as the same amount of the same ink or the like is printed, the hiding property does not change, but there are differences in ease of printing, manufacturing process, and the like. Furthermore, it should be understood for the purposes of the present invention that both paper and base film may be printed.

The above-mentioned adhesive layer is not limited to a single layer, but may be a mixed type or a type in which a plurality of adhesive layers are laminated. This is because different adhesives may be preferable depending on the difference in adhesiveness between the base material and the base film.

[0017]

EXAMPLES The concealing sheet of the present invention will be described in more detail with reference to the examples shown in the drawings. FIG. 1 is a sectional view showing an example of the concealing sheet 1 of the present invention. Corona treatment 3 is applied to the upper surface of the OPP which is the base film 2. The first adhesive layer 4 is provided on the side not subjected to the corona treatment 3 or the like. Further, the second adhesive layer 5 is provided on the side subjected to the corona treatment. Further, the paper 6 is laminated on the upper surface of the second adhesive layer 5. Printing 7 is applied to the lower surface of the paper 6.

FIG. 2 shows a postcard (base material) 8 shown in FIG.
FIG. 3 is a cross-sectional view showing a part which is pasted on and peeled off. The part that is most easily peeled off (adversely speaking, adhesion is difficult) is the base film OPP. Peeling occurs from the front and back sides of this OPP, but because one side is corona-treated and anchor-coated, peeling always occurs on the side not subjected to corona treatment or the like. Therefore, as shown in FIG. 2, peeling occurs on the lower surface of the base film 2. From this figure, when the concealing sheet is attached to the postcard, the printed surface has a concealing property, so that the characters on the postcard cannot be read at all.
When peeled off, the first adhesive layer 4 is transparent,
Can read. Also, once peeled, it cannot be re-bonded unless it is heated with an iron or a laminator. Therefore, it is possible to immediately determine whether or not it has been read by another person. In addition, recently, it has become well known that even conventional aluminum is not re-bonded, and therefore almost no one peels it off.

FIG. 3 shows an example of the second aspect of the present invention, in which the printing position is different from that of FIG. That is, in this example, the paper is not printed, but is applied to the side of the base film that has undergone corona treatment or the like. Depending on the ink or the like to be printed, this can print more neatly. In addition, even if the paper is peeled off, the printed surface remains, so the confidential information of the postcard cannot be read.

The manufacturing method of the example of FIG. 1 will be briefly described. First, concealment printing is applied to the paper. Bond the paper and the base film. The first adhesive layer, such as polyethylene, is fixed to the base film side by extrusion lamination.
Although the concealing sheet of this example is completed with this, printing for the user is performed on the surface of normal paper. When this concealing sheet is placed on a portion such as a postcard to be covered and heated, the first adhesive layer is melted and fused to the postcard.

[0021]

The concealing sheet of the present invention described in detail above has the following great effects. Adhesion to a substrate such as a postcard can be performed by the same method as in the past. Once peeled, it cannot be reattached. Since the sheet itself does not use expensive materials such as aluminum or a release agent, it is very inexpensive.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a concealing sheet according to the present invention.

FIG. 2 is a cross-sectional view showing how to use the example shown in FIG.

FIG. 3 is a cross-sectional view showing another example of the concealing sheet according to the present invention.

[Explanation of symbols]

 1 Concealing Sheet of the Present Invention 2 Base Film 3 Corona Treatment / Anchor Coat Treatment 4 First Adhesive Layer 5 Second Adhesive Layer 6 Paper 7 Printing Layer

Claims (2)

[Claims] 1. A concealing sheet, which comprises a concealment-printed paper, an adhesive layer, a base film, and an adhesive layer laminated in this order. 2. A concealing sheet comprising a paper, an adhesive layer, a concealing printed base film, and an adhesive layer laminated in this order.