JPH035319B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to changing the display of characters, marks, or photographs shown on identification documents, warranty cards, product warranty labels, etc., and changing the contents of containers, boxes, etc. This relates to a tampering prevention method for preventing changes due to extraction, replacement, etc.

Conventionally, as a method to prevent changes in the display shown on documents such as identification cards or changes in the contents of containers, there has been a method to prevent changes in the display on documents such as identification documents or the seals of containers. A method is to attach an adhesive sheet to the necessary areas to make the changes, and when the sheet is peeled off to make the above changes, there will be traces of peeling left on this sheet so that it can be easily identified. be.

Specifically, when attempting to peel off the adhesive sheet, the support of the sheet may be damaged, or the printed indicator layer provided on a part of the adhesive layer surface of the sheet may be destroyed, causing the sheet to become difficult to peel off. I try to leave a mark.

However, in the above method, when the adhesive sheet is peeled off at a low speed, it may be possible to peel off the sheet without leaving any traces of peeling, or the adhesive sheet may be peeled off without damaging items such as documents. This cannot be said to be a reliable method for preventing tampering, as it is possible to change the display or contents of items such as documents by changing the adhesive sheet.

Therefore, the inventors conducted extensive research with the aim of providing a more reliable tampering prevention method for preventing changes in the display and contents of certificates, etc., and as a result, they came up with the present invention.

That is, in order to prevent the display or content of an article made of a porous material from being changed, the present invention provides a light-transmitting support and a light-transmitting support on the support in a necessary portion of the article to prevent the change. A pressure-sensitive adhesive sheet consisting of a provided photo-curable pressure-sensitive adhesive layer is attached, a part of the light-curable pressure-sensitive adhesive layer is impregnated into the article, and then this pressure-sensitive adhesive sheet is irradiated with light to form the photo-curable pressure-sensitive adhesive. The present invention relates to a tampering prevention method characterized by photocuring the agent layer.

In the article that is tamper-proofed by the method of the present invention, the photocurable adhesive layer of the adhesive sheet attached to the surface of the article or the necessary parts for preventing tampering, such as the sealing part, is a part of the article. It is photocured while being impregnated with. Therefore, when the adhesive sheet is peeled off in an attempt to change the display or contents of this article, part of the article is peeled off along with the photocurable adhesive layer and damaged, and the display or contents of the article are changed. It may be impossible to change the contents, or it may leave a noticeable mark that makes it easy to tell that the contents have been changed.

Therefore, according to the tampering prevention method of the present invention, it is possible to change the display of articles made of porous materials such as documents such as identification cards, and to change the contents of articles such as containers and boxes made of porous materials. can be reliably prevented.

The pressure-sensitive adhesive sheet used in the method of this invention consists of a light-transmitting support and a photocurable pressure-sensitive adhesive layer provided on the support. Examples of the above-mentioned light-transmissive support include plastic films such as polyethylene, polypropylene, and polyester, and the thickness thereof is usually about 10 to 500 μm.

The photocurable adhesive layer provided on this support is made of, for example, an ordinary adhesive, a low molecular weight compound having a photopolymerizable carbon-carbon double bond (hereinafter referred to as a photopolymerizable compound), and a photopolymerization initiator. It is formed using a photocurable adhesive composition containing the following.

The above-mentioned adhesive may be a rubber-based polymer such as natural rubber, various synthetic rubbers, poly(meth)acrylic acid alkyl ester, (meth)acrylic acid alkyl ester and other unsaturated monomers copolymerizable therewith. The base polymer is an acrylic polymer such as a copolymer with a polymer, and if necessary, a crosslinking agent such as a polyisocyanate compound or an alkyl etherified melamine compound is blended therein. In addition, the above base polymer may have at least two photopolymerizable carbon-carbon double bonds introduced into the molecule by an appropriate means, and in this case, the photocurable adhesive composition may be intentionally added to the photocurable adhesive composition. It is not necessary to blend a photopolymerizable compound.

The above photopolymerizable compounds usually have a molecular weight of
The number is preferably about 10,000 or less, and the number of photopolymerizable carbon-carbon double bonds is preferably 2 to 6. Specific examples of this photopolymerizable compound include 1.
4-Butylene glycol diacrylate, 1.6
-Hexane glycol diacrylate, neopentyl glycol diacrylate, pentaerythritol diacrylate, polyethylene glycol diacrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol triacrylate, tetramethylolmethane tetraacrylate, and the like.

As the photopolymerizable compound, one type of the above-mentioned compounds may be used alone or two or more types may be used in combination, and the amount used is usually 1 to 1 to 100 parts by weight of the above-mentioned base polymer. The amount is preferably in the range of 100 parts by weight.

Examples of the above photopolymerization initiators include benzoin, benzoin isopropyl ether, benzoin ethyl ether, benzyl, diacetyl, benzophenone, ω-bromoacetophenone, chloroacetone, benzoquinone, anthraquinone, 2-
Examples include ethyl anthraquinone,
The amount used is usually 0.01 to 10 parts by weight per 100 parts by weight of the base polymer.

In order to form a photocurable adhesive layer using a photocurable adhesive composition formed by mixing the above-mentioned components, this composition is coated on the above-mentioned light-transmitting support, and the necessary You can heat it accordingly. The thickness of the photocurable adhesive layer formed in this way is usually 10 to 200 μm, more preferably 30 to 100 μm. If this thickness is too small, the photocurable adhesive layer impregnated into the article may be too small and a reliable tamper-proofing effect may not be obtained, which is undesirable.If this thickness is too large, the adhesive layer is photocured. This is not preferable because the light irradiation time required to achieve this is long.

In addition, the Young's modulus of this photocurable adhesive layer is usually in the range of 0.20 to 1.00 Kg/cm ² before photocuring, more preferably 0.30 to 0.70Kg/cm ² , and is usually 10.0 after photocuring. Kg/ ^cm2 or more, more preferably
It is better to have a weight of 20Kg/cm2 or ^more . The adhesive layer described above can be made to have such a Young's modulus by adjusting the blending ratio of each component of the photocurable adhesive composition.

If the Young's modulus of the adhesive layer before photo-curing is too small, the cohesiveness of the adhesive layer will be too low, resulting in adhesive extrusion, which is undesirable.If it is too large, it will be difficult to impregnate the article with the adhesive layer. This is not preferable because a reliable tampering prevention effect may not be obtained. Furthermore, if the Young's modulus of the pressure-sensitive adhesive layer after photocuring is too small, the pressure-sensitive adhesive sheet may be peeled off from the article at a low speed without damaging the article, which is not preferable.

The above Young's modulus before photocuring is based on the same photocurable adhesive layer as above formed on release paper, and the cross-sectional area of this adhesive layer is 4 mm ² .
A test piece was prepared by cutting it into a length of 20 mm, and this test piece was stretched at a tensile speed of 50 mm/min using an Instron universal tensile tester.The stress-strain curve was obtained and the inflection of the rise of this curve was determined. It can be found by drawing a tangent to a point and using the slope of this tangent. In addition, the Young's modulus after photocuring is determined by forming a photocurable adhesive layer similar to the above on release paper, irradiating it with light to photocure it, and using the photocured adhesive layer in the same manner as above. .

The tampering prevention method of the present invention is carried out using a pressure-sensitive adhesive sheet composed of the above-described light-transmissive support and a photocurable pressure-sensitive adhesive layer. Items that are subject to tampering prevention using the method of this invention are characters and marks shown on the surface of identification documents, membership cards, product warranty labels, and other documents made of porous materials such as paper, nonwoven fabric, and woven fabric. , items whose display, such as photographs, should be prevented from being changed, or items, such as containers and boxes made of the above-mentioned porous materials, whose contents should be prevented from being changed when their contents are removed or replaced.

In the method of the present invention, first, the above-mentioned adhesive sheet is attached to the surface of a document or a sealed part of a container, etc., and a part of the photocurable adhesive layer is impregnated into the document or an article such as a container. let
After pasting the adhesive sheet above, it is usually left for 20 minutes or more, preferably 2 hours or more, or it is usually left for 1 to 2 hours.
It is preferable to press at a pressure of about 10 kg/cm ² to sufficiently impregnate the article with the photocurable adhesive layer.

After the above impregnation, light having a wavelength of 200 to 450 nm is irradiated from the transparent support side of the adhesive sheet using a high pressure mercury lamp, an ultra-high pressure mercury lamp, etc. for usually 10 seconds or more, preferably 60 seconds or more to make the photocurable adhesive. The agent layer is photocured. As a result, this adhesive layer is photocured while being partially impregnated into the article, so if you try to peel off the adhesive sheet from the article and change the display or contents of this article, the article will be damaged. Such alterations to the article can be reliably prevented, since such alterations may become impossible or leave a noticeable mark that allows the alterations to be easily discerned.

Note that the surface of the pressure-sensitive adhesive sheet described above may be printed if necessary. Further, when preparing the pressure-sensitive adhesive sheet in advance, a light-transmissive support may be printed, or a photo-curable pressure-sensitive adhesive layer may be printed.

Examples of this invention will be described below. In addition, in the following, parts mean parts by weight.

Example 1 35% by weight of an acrylic copolymer obtained by copolymerizing 3 parts of acrylic acid and 97 parts of butyl acrylate
1 part of polyisocyanate (trade name Mitek GP500A manufactured by Mitsubishi Chemical Industries, Ltd.), 20 parts of trimethylolpropane triacrylate, and 1 part of benzophenone were mixed into a toluene solution and thoroughly stirred to obtain a uniform photocurable adhesive composition. . This composition has a thickness of 38μ
Spread it evenly onto a polyethylene terephthalate film of 50 µm so that the thickness after drying is 50 μm.
A photocurable adhesive layer was formed by drying at 100°C for 5 minutes to obtain an adhesive sheet.

This adhesive sheet was made into a size of 20 mm x 20 mm, and it was pasted on the printed area of a 100 mm x 100 mm piece of high-quality paper (manufactured by Oji Paper Co., Ltd., brand name New OK high-quality paper, 64 g/cm ² ) for 1 hour. This adhesive sheet was then left to stand and was then irradiated with ultraviolet rays for 20 seconds from a distance of 30 cm using a 2KW high-pressure mercury lamp. When the adhesive sheet was then peeled off at a low speed (51 mm/min), about 90% of the high-quality paper in the area where the adhesive sheet was attached (printed display area) was damaged.

The Young's modulus of the photocurable adhesive layer before UV irradiation was 0.40 Kg/cm ² , and the Young's modulus after UV irradiation was 20.0 Kg/cm ² .

Comparative Example 1 The adhesive sheet obtained in Example 1 was made into a size of 20 mm x 20 mm, and this was pasted on the printed display area of a 100 mm x 100 mm piece of high-quality paper (New OK high-quality paper mentioned above) for 1 hour. When the pressure-sensitive adhesive sheet was left to stand and then peeled off at a low speed (51 mm/min), the pressure-sensitive adhesive sheet could be peeled off with almost no damage to the high-quality paper.

Comparative Example 2 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 20 parts of trimethylolpropane triacrylate and 1 part of benzophenone were not blended, and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 using this composition. I got it.

Make this adhesive sheet into a size of 20mm x 20mm, paste it on the printed display area of 100mm x 100mm high-quality paper (New OK high-quality paper above), leave it for 1 hour, and then paste it on the above adhesive sheet. Ultraviolet rays were irradiated in the same manner as in Example 1. Next, when this adhesive sheet was peeled off at a low speed (51 mm/min), the adhesive sheet could be peeled off with almost no damage to the high-quality paper.

The Young's modulus of the adhesive layer in the above-mentioned adhesive sheet was 0.40 Kg/cm ² both before and after UV irradiation.

Comparative Example 3 The adhesive sheet obtained in Comparative Example 2 was made into a size of 20 mm x 20 mm, and this was pasted on the printed display part of a 100 mm x 100 mm piece of high-quality paper (New OK high-quality paper mentioned above) for 1 hour. When the pressure-sensitive adhesive sheet was left to stand and then peeled off at a low speed (51 mm/min), the pressure-sensitive adhesive sheet could be peeled off with almost no damage to the high-quality paper.

Example 2 A photocurable adhesive composition and an adhesive sheet using this composition were obtained in the same manner as in Example 1 except that 20 parts of pentaerythritol triacrylate was used instead of 20 parts of trimethylolpropane triacrylate. . Using this adhesive sheet, in the same manner as in Example 1, the adhesive sheet was attached to the print display area on the surface of the high-quality paper and irradiated with light. When this adhesive sheet was then peeled off at a low speed (51 mm/min), more than 90% of the high-quality paper in the pasted area (printed display area) of this sheet was damaged.

As is clear from the above embodiments, according to the tampering prevention method of the present invention, if the adhesive sheet is peeled off to change the display or contents of the article, the article will be damaged, so the above changes cannot be made. Tampering can be reliably prevented.

Claims (1)

[Scope of Claims] 1. In order to prevent changes in the display or contents of an article made of a porous material, a light-transmitting support and a light-transmitting support on the support are provided in a necessary part of the article to prevent the change. A pressure-sensitive adhesive sheet consisting of a photo-curable pressure-sensitive adhesive layer provided on the substrate is attached to impregnate a part of the photo-curable pressure-sensitive adhesive layer into the article, and then this pressure-sensitive adhesive sheet is irradiated with light to form the photo-curable pressure-sensitive adhesive layer. A tampering prevention method characterized by photo-curing an adhesive layer. 2. The tampering prevention method according to claim 1, wherein the article is made of paper, nonwoven fabric, or woven fabric. 3 Young's modulus of the photocurable adhesive layer before photocuring
The tampering prevention method according to claim 1 or 2, wherein the tampering prevention method is 0.20 to 1.00 Kg/cm ² and 10.0 Kg/cm ² or more after photocuring.