JP2010175812A - Counterfeit prevention medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a counterfeit prevention medium which combines a diffraction structure and a structure having a color change effect different from the diffraction structure and which can easily perform determination without mixing optical effects and especially without burying the optical effect of the diffraction structure in the color change effect. <P>SOLUTION: The counterfeit prevention medium has a diffraction structure forming area and a diffraction structure nonforming area on a supporting body and has a color change effect layer which exhibits the color change effect in a visible light region in the diffraction structure nonforming area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an anti-counterfeit medium that is used by being affixed to securities such as gift certificates and stock certificates, credit cards, certificates, and other items that require authenticity determination.

  In recent years, an OVD (Optical variable device) that expresses a stereoscopic image or a special decoration image using optical phenomena such as light interference, diffraction, reflection, and the like has been used as a forgery prevention means. Examples of the OVD include a hologram, a diffractive structure, an ink that causes a color change (color change) depending on a viewing angle, an optical interference multilayer film, and the like. Since these OVDs require advanced manufacturing techniques and have a unique visual effect, they are used by being attached to credit cards, securities, certificates, etc. as anti-counterfeiting means.

  However, in recent years, due to technological progress, it is not always possible to manufacture and forge a similar product that cannot be distinguished from the real product at a glance with a conventional OVD. Therefore, in order to achieve the objectives of authenticating articles and preventing counterfeiting, OVD has been subjected to more complicated and finer processing than before.

  OVD that has been subjected to complicated and fine processing makes it difficult to forge the OVD itself, but at the same time, the method for determining authenticity tends to be complicated and sophisticated. For example, when the OVD has a diffractive structure, it is common to rely on visual observation of the OVD for operation, but it is complicated and fine generated with a diffractive structure that has been subjected to complicated and fine processing. It is difficult for all people to uniformly discriminate images with the naked eye and to perform accurate authenticity determination. In fact, when determining the authenticity of an OVD using a diffractive structure, most people often make a determination based on whether or not the diffractive structure (OVD) itself exists, rather than identifying the image generated by these. That is, it can be said that the method for performing complicated and fine processing on the OVD itself does not achieve a sufficient anti-counterfeit effect in the sense that the fine processing itself is not effectively used.

  On the other hand, an anti-counterfeit method for producing a pattern image using invisible light in the infrared light or ultraviolet light range as an OVD and visualizing this pattern image using a specially processed filter or device to determine authenticity (For example, refer to Patent Document 1), however, there is a problem that it is not convenient because authenticity cannot be determined without a special device paired with OVD. In this respect, it is disadvantageous as an anti-counterfeiting means for articles used by an unspecified number of people such as banknotes.

  Therefore, a forgery prevention medium that combines a diffraction structure and an optical effect other than the diffraction structure has been proposed as an anti-counterfeit medium that has a high anti-counterfeit effect and can easily determine the authenticity without using a special device.

  An example is a forgery prevention medium such as a demetallized hologram that combines the optical effect of the hologram or the diffractive structure with the optical effect of the presence or absence of the reflective layer by partially providing a reflective layer of the diffractive structure by etching or the like. It is.

  As another example, a multilayer film in which low-refractive index materials and high-refractive index materials are alternately stacked is provided so as to be in contact with the layer forming the diffractive structure in the vertical direction, thereby improving the visibility of the hologram and color change. Examples of anti-counterfeit media (see Patent Document 2) that combine the effects of, and anti-counterfeit media that have a unique visual effect consisting of a combination of an optical pattern such as a hologram or a diffractive structure, and a color shift foil or ink ( An example is described in Patent Document 3).

Japanese Patent No. 3988458 Japanese Unexamined Patent Publication No. 7-191595 JP 2003-520986 A

The Second Physics Dictionary, Maruzen "Wave Interference", pages 1132-1137, 2005

  As the prior art of the anti-counterfeit medium combining the diffractive structure and another type of optical effect, in the configurations described in Document 2 and Document 3, the multilayer film, the color misalignment foil, or the ink is in contact with the formation region of the diffractive structure in the vertical direction. Etc. are provided. In this configuration, the brightness of the image due to the diffractive structure can be increased because the layers are stacked in the vertical direction, while the diffracted light from the diffractive structure (for example, a relief hologram) and the multilayer film, color misalignment foil, ink, etc. Since the color change effects due to the above overlap, when ordinary people use these for the authenticity determination of the anti-counterfeit medium, there is a problem that their optical effects are difficult to distinguish.

  Therefore, the problem to be solved by the present invention is that the anti-counterfeit medium combining the diffractive structure and the structure having a different color change effect does not mix the optical effects of each other, and each of them is independent. It is to provide an anti-counterfeit medium that can be easily identified.

  The invention according to claim 1 for solving the above problem has a diffractive structure formation region and a diffractive structure non-formation region on a support, and exhibits a color change effect in the visible light region in the diffractive structure non-formation region. It is a forgery prevention medium characterized by including a color change effect layer.

  The invention according to claim 2 is the anti-counterfeit medium according to claim 1, wherein the color change effect layer is made of a dielectric multilayer film.

  The invention according to claim 3 is the anti-counterfeit medium according to claim 2, wherein the dielectric multilayer film reflects either visible reflected light or invisible reflected light depending on a viewing angle. is there.

  The invention according to claim 4 is the anti-counterfeit medium according to claim 1 or 2, wherein the diffraction structure forming region and / or the diffraction structure non-forming region has a reflective layer. is there.

  The invention according to claim 5 is the anti-counterfeit medium according to any one of claims 1 to 3, further comprising an absorption layer in the diffraction structure non-formation region.

  Since the present invention is configured as described above, the following effects are obtained.

First, according to the invention described in claim 1, by providing the diffraction structure and the structure having the color change effect on one side of the support in separate areas instead of vertically overlapping each other, each optical effect can be obtained. Can be separated and observed without mixing.
In addition, by changing the visible light wavelength to the invisible light wavelength at a certain finite angle (for example, an observation direction of 45 °), it is possible to determine whether the color can be observed or not based on a binary change. It becomes possible.

  According to the second aspect of the present invention, since the color change effect is an effect of a dielectric multilayer film, a structure having the color change effect can be produced by a simpler method. The color change effect is manifested by, for example, a method of aligning cholesteric liquid crystal or coating with ink containing a pearl pigment. In the former case, equipment for aligning (UV device) is required. In this case, there is a problem that the film thickness becomes large and it is difficult to obtain a transfer foil. Compared with these, the multilayer film system can be said to be simple.

  The invention according to claim 3 is to change the visible light wavelength from the visible light wavelength to the invisible light wavelength at a certain finite angle (for example, an observation direction of 45 °).

  According to the invention described in claim 4, by providing the reflective layer in both the diffractive structure forming region and the non-formed region, the optical effect by the diffractive structure and the effect by the color change from the visible light wavelength to the invisible light wavelength are achieved. Can be increased.

The figure explaining the structure of a dielectric multilayer. The cross-sectional view which shows the forgery prevention medium which becomes this invention. The top view which observed the forgery prevention medium of FIG. 2 from the perpendicular direction. The top view which observed the forgery prevention medium of FIG. 2 from the diagonal direction. FIG. 3 is another cross-sectional view showing a forgery prevention medium according to the present invention. The top view which observed the forgery prevention medium of FIG. 5 from the perpendicular direction. The top view which observed the forgery prevention medium of FIG. 5 from the diagonal direction. The figure which illustrates typically the optical interference phenomenon by a thin film. The figure which illustrates typically the wavelength range of the optical interference which Formula 1 and Formula 2 show. FIG. 6 is another cross-sectional view showing the forgery prevention medium according to the present invention. The top view which observed the forgery prevention medium of FIG. 10 from the perpendicular direction. The top view which observed the forgery prevention medium of FIG. 10 from the diagonal direction. The cross-sectional view which made the forgery prevention medium which becomes this invention the sticker shape. The cross-sectional view which made the forgery prevention medium which becomes this invention the transfer foil shape.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing the forgery prevention medium according to the present invention. In FIG. 2, the anti-counterfeit medium 11 has a diffractive structure forming layer 3 on one side of a support 2. The diffractive structure forming layer 3 includes a diffractive structure forming region 4 and a diffractive structure non-forming region 51. The diffractive structure forming region 4 is composed of unevenness indicating the diffractive structure and the reflective layer 7 in plan contact therewith, and the diffractive structure non-forming region 51 is a dielectric multilayer film layer 61 satisfying the following formula 1, And a reflective layer 7 in contact with. Here, the diffracted light by the diffractive structure forming region 4 can be observed as a pattern by diffracted light only when the anti-counterfeit medium 11 is observed from the vertical direction from the support 2 side.
380 <Y
200 <Y {1-1 / μ ² } ^1/2 <380 Equation 1
(Y = μd / m, m = 1, 2, 3,...)

  FIG. 3 is a front view of the anti-counterfeit medium 11 of FIG. 2 observed from the vertical direction from the support 2 side. Here, the cross-sectional view of FIG. 2 corresponds to the AA cross-section of FIG. When the anti-counterfeit medium 11 is observed from the vertical direction, a diffraction structure forming region 41 in which a pattern by diffracted light appears corresponding to the position of the diffraction structure forming region 4 in FIG. In addition, in the diffraction structure non-formation region 512 corresponding to the position of the diffraction structure non-formation region 51 of FIG. 2, the dielectric multilayer film layer 61 appears to be transparent, and the color of the reflective layer 7 therebelow can be observed.

  FIG. 4 is a perspective view of the anti-counterfeit medium 11 of FIG. 3 observed from an oblique direction. When the anti-counterfeit medium 11 is observed from an oblique direction, the diffracted light pattern of the diffractive structure forming region 41 corresponding to the position of the diffractive structure forming region 4 in FIG. 2 does not appear. Also, in the diffractive structure non-formation region 511 where the color of the dielectric multilayer film layer 61 corresponds to the position of the diffractive structure non-formation region 51 of FIG. 2, the color changes unlike FIG. I can observe.

  Hereinafter, FIGS. 5 to 7 will be described in comparison with FIGS.

  FIG. 5 is another sectional view showing the forgery prevention medium according to the present invention. In FIG. 5, the anti-counterfeit medium 12 has a diffractive structure forming layer 3 on one side of a support 2. The diffractive structure forming layer 3 includes a diffractive structure forming region 4 and a diffractive structure non-forming region 52. The diffractive structure forming region 4 is composed of irregularities showing the diffractive structure and the reflective layer 7 in contact therewith, and the diffractive structure non-formed region 52 is a dielectric multilayer film layer 62 satisfying the following formula 2 and a reflective layer in contact with the dielectric multilayer film layer 62 7

Here, the diffracted light by the diffractive structure forming region 4 can be observed as a pattern by diffracted light only when the anti-counterfeit medium 11 is observed from an oblique direction from the support 2 side.
200 <Y <380
Y {1-1 / μ ² } ^1/2 <200 Formula 2
(Y = μd / m, m = 1, 2, 3,...)

  When comparing FIG. 2 and FIG. 5, the dielectric multilayer film layer is different from 61 in FIG. 2 and 62 in FIG. 5, except that the observable direction of the diffracted light pattern by the diffractive structure formation region 4 is different. Are the same configuration.

  FIG. 6 is a front view of the anti-counterfeit medium 12 of FIG. 5 observed from the vertical direction from the support 2 side. Here, the cross-sectional view of FIG. 5 corresponds to the BB cross-section of FIG. When the anti-counterfeit medium 12 is observed from the vertical direction, the diffracted light pattern of the diffractive structure forming region 41 corresponding to the position of the diffractive structure forming region 4 in FIG. 5 does not appear. Further, in the diffractive structure non-formation region 521 where the color of the dielectric multilayer film layer 62 appears corresponding to the position of the diffractive structure non-formation region 52 in FIG. 5, the color due to the dielectric multilayer film 62 can be observed.

  3 and FIG. 6, the dielectric multilayer film layer 61 is transparent in FIG. 3 and the color of the reflective layer 7 below can be observed, whereas in FIG. 6, the color due to the dielectric multilayer film layer 62 is I can observe.

  FIG. 7 is a perspective view of the anti-counterfeit medium 12 of FIG. 5 observed from an oblique direction. When the anti-counterfeit medium 12 is observed from an oblique direction, a diffraction structure forming region 41 in which an optical effect appears can be observed corresponding to the position of the diffraction structure forming region 4 in FIG. Further, in the diffractive structure non-formation region 522 corresponding to the position of the diffractive structure non-formation region 52 in FIG. 5, the dielectric multilayer film 62 looks transparent, and the color of the reflective layer 7 therebelow can be observed.

  When FIG. 4 is compared with FIG. 7, in FIG. 4, the color of the dielectric multilayer film 61 can be observed by color change, whereas in FIG. 7, the dielectric multilayer film 62 appears to be transparent. The color of the layer 7 can be observed.

  From FIG. 2 to FIG. 4 and FIG. 5 to FIG. 7, when the dielectric multilayer film satisfies Equation 1, the dielectric multilayer is sometimes transparent when observed from the vertical direction. When 2 is satisfied, the dielectric multilayer film is sometimes transparent when observed from an oblique direction. Furthermore, the diffracted light pattern in the diffractive structure forming region 41 can be observed only in the observation direction in which the dielectric multilayer film layer is transparent.

  Next, with reference to FIG. 8 and FIG.

FIG. 8 schematically shows, using geometric optics, optical interference that occurs when light having a wavelength λ is incident from the air at an incident light angle i on a thin film having a refractive index μ and a thickness d. is there. Optical interference occurs when the optical path difference between the light passing through the path ABC in FIG. 8 and the light passing through the path DC is an integral multiple of the incident light wavelength λ (see Non-Patent Document 1).
This can be expressed as an expression:
2 μd · cos (r) = mλ Equation 3
(However, m = 1, 2, 3, ...)
From Snell's law,
sin (i) = μsin (r) Equation 4
Using Expression 3 and Expression 4, λ = [2 μd {1- (sin (i)) / μ) ² } ^1/2 ] / m Expression 5
Here, from the condition of the angle i of incident light, 0 ° <i <90 ° Equation 6
From Equation 5 and Equation 6,
2 μd / m>λ> [2 μd {1- (1 / μ) ² } ^1/2 ] / m Expression 7
Is obtained.

  FIG. 9 shows a wavelength range that causes optical interference when the wavelength of light is plotted on the horizontal axis and the visible light is changed from 400 nm to 760 nm so that the optical interference is satisfied when the formula 1 or 2 is satisfied. It represents the setting. By considering the magnitude relationship between the optical interference wavelength range 611 indicated by Equation 1 and the optical interference wavelength range 622 indicated by Equation 2 and the wavelength range indicated by Equation 7, Equation 1 and Equation 2 can be derived.

In order to derive Equation 1, first, the range of possible values of the wavelength λ represented by Equation 7 is such that the maximum value is in the infrared light region (greater than 760 nm) and the minimum value is in the visible light region ( 400 nm to 760 nm) (see range 611 in FIG. 9).
760 <2 μd / m
400 <[2 μd {1- (sin (i) / μ) ² } ^1/2 ] / m <760 nm.
(However, m = 1, 2, 3 ...)
Therefore,
380 <Y
200 <Y [{1-1 / μ ² } ^1/2 ] <380 Formula 1
(Y = μd / m, m = 1, 2, 3,...)
Is guided.

  On the other hand, it can be seen from Equation 5 that when the values of the refractive index μ, the thickness d, and m do not change, the possible range of the wavelength λ changes depending on the value of the incident angle i. That is, when the values of the refractive index μ and the thicknesses d and m are determined so as to satisfy the condition of Equation 1, the possible range of the wavelength λ where the optical interference of the thin film occurs depends on the value of the incident angle i. It can be seen that the maximum value (when i = 0 °) becomes an infrared light region and can be observed transparently, and the minimum value (when i = 90 °) becomes a visible light region and colors can be observed.

The same calculation can be performed when the thin film is a multilayer film of two layers, three layers,..., K layers,. In this case, the refractive index μ _k and the thickness d _k to be satisfied by the kth thin film are as follows, and it can be seen that the same shape is obtained.
380 <Y
200 <Y [{1-1 / μ ² } ^1/2 ] <380 Formula 1 ′
(However, Y = μ _k d _k / m, m = 1, 2, 3,...).

Next, in order to derive Equation 2, the range of possible values of wavelength λ represented by Equation 7 is such that the maximum value is in the visible light region (400 nm to 760 nm) and the minimum value is in the ultraviolet light region ( (Less than 400 nm) (see range 621 in FIG. 9).
400 <2 μd / m <760
[2 μd {1-1 / μ) ² } ^1/2 ] / m <400 Equation 9
(However, m = 1, 2, 3 ...)
Therefore, 200 <Y <380
Y [{1-1 / μ ² } ^1/2 ] <200 Equation 2
(Y = μd / m, m = 1, 2, 3,...)
Is guided.

On the other hand, it can be seen from Equation 5 that when the values of the refractive index μ, the thickness d, and m do not change, the possible range of the wavelength λ changes depending on the value of the incident angle i.
That is, when the values of the refractive index μ and the thicknesses d and m are determined so as to satisfy the condition of Equation 2, the possible range of the wavelength λ where the optical interference of the thin film occurs depends on the value of the incident angle i. It can be seen that the maximum value (when i = 0 °) becomes the visible light region and the color can be observed, and the minimum value (when i = 90 °) becomes the ultraviolet light region and can be observed transparently.

The same calculation can be performed when the thin film is a multilayer film of 2 layers, 3 layers,..., K layers,. In this case, the refractive index μ _k and the thickness d _k to be satisfied by the kth thin film are as follows, and it can be seen that the same shape is obtained.
200 <Y <380
^{Y [{1-1 / μ 2}} 1/2] <200 ··· Equation 2 '
(However, Y = μ _k d _k / (2m−1), m = 1, 2, 3,...).

  Next, as an example using the configuration according to the present invention, an example in which a dielectric multilayer film layer 61 satisfying Expression 1 and a dielectric multilayer film layer 62 satisfying Expression 2 are combined will be shown.

  FIG. 10 is another cross-sectional view showing the forgery prevention medium according to the present invention. In FIG. 10, the anti-counterfeit medium 13 has the diffractive structure forming layer 3 on one side of the support 2. The diffractive structure forming layer 3 includes a diffractive structure forming region 4 and diffractive structure non-forming regions 51, 52, and 53. The diffractive structure forming region 4 is composed of unevenness indicating a diffractive structure and a reflective layer 7 in contact therewith. The diffractive structure non-formation regions 51 and 52 each have a dielectric multilayer film layer 61 satisfying the expression 1 and a dielectric multilayer film layer 62 satisfying the expression 2, and each dielectric multilayer film layer is planarly arranged. A reflective layer 7 is provided so as to be in contact therewith. Further, the reflection layer 7 is provided in the diffraction structure non-formation region 53 so as to be in contact with the diffraction structure formation layer 3. Here, the diffracted light by the diffractive structure forming region 4 can be observed as a pattern by diffracted light only when the anti-counterfeit medium 11 is observed from the vertical direction from the support 2 side.

FIG. 11 is a plan view of the anti-counterfeit medium 13 of FIG. 10 observed from the vertical direction from the support 2 side. Here, the cross-sectional view of FIG. 10 corresponds to the CC cross-section of FIG. When the anti-counterfeit medium 13 is observed from the vertical direction, the diffraction structure forming region 41 in which the optical effect appears can be observed corresponding to the position of the diffraction structure forming region 4 in FIG. Further, in the center, the diffractive structure non-formation region 521 can observe the color due to the dielectric multilayer film 62 corresponding to the position where the dielectric multilayer films 61 and 62 are provided in FIG. In the left and right diffraction structure non-formation regions 512, the dielectric multilayer film layer 61 appears to be transparent, so that the color of the reflective layer 7 therebelow can be observed. Furthermore, the color of the reflective layer 7 can be observed in the diffraction structure non-formation region 53 where the dielectric multilayer film is not provided.

  FIG. 12 shows the anti-counterfeit medium 13 of FIG. 10 observed from an oblique direction. When the anti-counterfeit medium plane 13 is observed from an oblique direction, a diffraction structure forming region 41 in which an optical effect appears can be observed corresponding to the position of the diffraction structure forming region 4 in FIG. Further, it can be observed that the left and right diffractive structure non-formation regions 511 change in color due to the dielectric multilayer film 61 corresponding to the positions where the dielectric multilayer films 61 and 62 of FIG. 10 are provided. In the central region 522 where the diffractive structure is not formed, the dielectric multilayer film 62 appears to be transparent, so that the color of the reflective layer 7 therebelow can be observed. Furthermore, the color of the reflective layer 7 can be observed in the diffraction structure non-formation region 53 where the dielectric multilayer film is not provided.

  Thus, by providing the diffractive structure forming region 4 and the dielectric multilayer film 61 or the dielectric multilayer film 62 so as not to contact each other, it is possible to observe without mixing the optical effects of each other and to further prevent forgery. It becomes a high structure.

  FIG. 13 is a cross-sectional view of the anti-counterfeit medium according to the present invention having a sticker shape. In FIG. 13, a sticker-shaped anti-counterfeit medium cross section 14 has a configuration in which an adhesive layer 8 is provided below the reflective layer 7 in the anti-counterfeit medium 11 of FIG. By providing the adhesive layer 8, it becomes possible to attach the anti-counterfeit medium of the present invention as a sticker to an article that requires authenticity determination.

  FIG. 14 is a cross-sectional view of the anti-counterfeit medium according to the present invention having a transfer foil shape. In FIG. 14, a transfer foil-shaped forgery prevention medium 15 is provided with a peeling protective layer 9 between the support 2 and the diffraction structure forming layer 3 in the forgery prevention medium 11 of FIG. The adhesive layer 8 is provided below. By providing the peeling protection layer 9 and the adhesive layer 8, it becomes possible to attach the anti-counterfeit medium of the present invention as a transfer foil to an article that requires authenticity determination. When the transfer foil is transferred to the article, the support 2 is peeled off by heat or pressure during transfer, and the layer below the support 2 adheres to the article.

  Hereinafter, each layer will be described in detail.

(Support)
The support 2 is generally a polyethylene terephthalate resin film having a stable thickness and high heat resistance, but is not limited thereto. As other materials, polyethylene naphthalate resin films, polyimide resin films, and the like are known as films having high heat resistance, and can be used for the same purpose. In addition, other films such as polyethylene, polypropylene, and heat-resistant vinyl chloride can be used depending on the coating conditions and the drying conditions of the coating liquid. Further, as long as there is no influence on other layers, the support 2 may be subjected to processing such as antistatic processing, mat processing, embossing processing, or the like.

(Diffraction structure forming layer)
The diffractive structure forming layer 3 is a layer that exhibits an optical effect by light diffraction. When forming a relief-type diffractive structure, the main material may be any of thermoplastic resin, thermosetting resin, ultraviolet light, or electron beam curable resin. In the case of visually observing, it is desirable to use a material having high transparency with respect to the visible light wavelength.

Examples of materials that can be used for the diffraction structure forming layer 3 include polyisocyanates such as thermoplastic resins such as acrylic resins, epoxy resins, cellulose resins, and vinyl resins, acrylic polyols and polyester polyols having reactive hydroxyl groups, and the like. Is added as a crosslinking agent, crosslinked urethane resin, thermosetting resin such as melamine resin and phenolic resin, UV or electron beam curable resin such as epoxy (meth) acryl, urethane (meth) acrylate, etc. Can be used in combination. Moreover, even if it is resin other than the above, if an OVD image can be formed, it can be used suitably.

(Dielectric multilayer film)
The dielectric multilayer films 61 and 62 are obtained by laminating two or more types of dielectric materials having different refractive indexes and having a film thickness satisfying the formula 1 and the formula 2. The usable materials are, for example, , Magnesium oxide (refractive index n = 1.7 at a wavelength of 550 nm), silicon dioxide (n = 1.5), magnesium fluoride (n = 1.4), calcium fluoride (n = 1.3-1. 4), cerium fluoride (n = 1.6), aluminum fluoride (n = 1.3), aluminum oxide (n = 1.6), titanium dioxide (n = 2.5), zirconium dioxide (n = 2.0), zinc sulfide (n = 2.3), zinc oxide (n = 2.1), indium oxide (n = 2.0), cerium dioxide (n = 2.2), tantalum oxide (n = 2.1).

  The total film thickness of the multilayer film is desirably 1 μm or less. If it exceeds 1 μm, the flexibility is poor, and the multilayer structure may be destroyed by cracks or the like. Moreover, when producing a dielectric multilayer film, it is desirable to use a combination of materials with sufficient interlayer adhesion between layers, such as a combination of magnesium fluoride and zinc sulfide.

  The thickness of each layer in the dielectric multilayer film is preferably within an accuracy of several nanometers for the purpose of causing multilayer optical interference, and if the film thickness can be controlled with this level of precision, Any film forming method can be used. In particular, the dry method is excellent for the production of a thin film. For this, a normal vapor deposition method, a physical vapor deposition method such as sputtering, or a chemical vapor deposition method such as a CVD method can be used.

(Reflective layer)
The reflective layer 7 is made of a material having a refractive index different from that of the material constituting the diffractive structure forming region 4 and the dielectric multilayer films 61 and 62 in order to enhance the optical effect. Examples of the material to be used include metal materials such as Al, Sn, Cr, Ni, Cu, and Au having high optical reflectivity. The film thickness varies depending on the reflectivity and application of each material, but is generally about 0.1 to 100 nm.

  The reflective layer 7 may be provided on the entire surface, but may be formed with a pattern such as a character or a picture. In this case, the design is improved and the processing is complicated, and a higher forgery prevention effect is given. I can do it. In this case, it is desirable that the patterned reflective layer 7 is provided at least in both the diffraction structure forming region 4 and the diffraction structure non-forming regions 51 and 52. Further, if possible, providing a non-diffractive structure forming region 53 where the dielectric multilayer films 61 and 62 are not provided includes a more effective forgery prevention medium.

  As a method of providing the reflective layer 7 in a pattern, a method of providing a metal thin film after forming a soluble resin in a pattern, and washing and removing the soluble resin and the metal thin film layer in that portion, or a metal thin film layer After printing in a pattern using acid- or alkali-resistant resin, a method of etching the metal thin film with acid or alkali, or by exposing to light, a resin material that dissolves or becomes difficult to dissolve is applied, and a desired material is applied. For example, a method of removing unnecessary portions by washing or etching after exposure through a pattern-shaped mask can be used. The above is an example, and the present invention is not limited to these. Any known technique for partially forming a metal thin film can be used as appropriate.

(Adhesive layer)
The adhesive layer 8 is provided to enable the forgery prevention medium of the present invention to be attached to an arbitrary article. As a method for providing the adhesive layer 8, a known method such as a gravure printing method, a screen printing method, or an offset printing method is appropriately used.

(Peeling protection layer)
When the anti-counterfeit medium according to the present invention is used as a transfer foil, the peeling protective layer 9 is a layer that is peeled off from the support 2 by a hot stamp or the like and adhered to the article side. After peeling from the support 2, a diffractive structure is formed. Since it covers the layer 3 and is exposed on the outermost surface, it is resistant to damage caused by external factors such as mechanical damage and rubbing when carrying it, and is resistant to living substances (such as liquor and water), and also serves to protect the diffraction structure forming layer 3 Plays. As long as it has such performance and resistance, any conventionally known thermoplastic resin, thermosetting resin, ultraviolet ray, or electron beam curable resin can be used as the material of the peeling protection layer 9. . Examples include thermoplastic resins such as acrylic resins, cellulose resins, polyether resins, polyimide resins, polycarbonate resins, and polyamideimide resins, urethane curable resins, thermosetting resins such as melamine curable resins, and epoxy curable resins. UV or electron beam curable resins such as epoxy (meth) acryl, urethane (meth) acrylate, etc. are not limited to these.

  In addition, when it is difficult to peel off the support 2 and the peeling protection layer 9 due to transfer conditions or the like, a conventionally known peeling layer may be separately provided between the support 2 and the peeling protection layer 9 and the peeling is light. In the case where it is too large, the peeling may be adjusted similarly by performing a conventionally known easy adhesion treatment. Furthermore, a known lubricant can be appropriately selected and added to the peeling protective layer 9 for the purpose of imparting friction resistance.

  The present invention will be described in detail with specific examples and comparative examples.

<Example>
On one side of the support 2 made of a transparent polyethylene terephthalate film having a thickness of 25 μm, an anti-counterfeit medium sticker having the following configuration was formed.

  First, as the diffractive structure forming layer 3, a composition having the following blending ratio is applied by a gravure printing method at a coating thickness of 1 μm and a drying temperature of 110 ° C., and a diffractive structure relief pattern is applied to a part of the region by roll embossing. Formed. Here, the diffracted light from the diffractive structure forming region 4 is observed when observed from 0 ° to 45 ° when the direction perpendicular to the anti-counterfeit medium plane is 0 ° and the parallel direction is 90 °. Only designed so that the pattern by diffracted light can be observed.

(Diffraction structure forming layer)
Mixture of vinyl chloride-vinyl acetate copolymer and urethane resin 25 parts methyl ethyl ketone 70 parts toluene 30 parts

  Next, a dielectric multilayer film 61 satisfying the formula 1 was provided by vacuum deposition on the entire surface of the diffractive structure forming layer 3 where the diffractive structure relief pattern was not formed. The dielectric multilayer film 61 is provided so that optical interference with a boundary wavelength of 760 nm between visible light and invisible light (infrared light) occurs at an incident light angle of 45 °. By providing in this way, optical interference of invisible light (infrared light) occurs when the incident light angle is smaller than 45 °, and visible light (red) when the incident light angle is larger than 45 °. FIG. 1 shows the state of incident light and reflected light, and the material, refractive index, and film thickness of the fabricated dielectric multilayer film.

(a formula)
(SiO ₂ layer)
By substituting μ = μ _S = 1.5, λ = 760 (nm), i = 45 °, and m = 1 into Equation 5, d _S = 287 (nm) was obtained. This satisfies the condition of substituting μ = μ _S = 1.5 and m = 1 into Equation 1, 253 (nm) <d _S <340 (nm).

(TiO ₂ layer)
By substituting μ = μ _T = 2.5, λ = 760 (nm), i = 45 °, and m = 1 into Equation 5, d _T = 165 (nm) was obtained. This satisfies the condition 152 (nm) <d _S <165 (nm) when μ = μ _T = 2.5 and m = 1 are substituted into Equation 1.

  Further, an Al layer having a thickness of 50 nm was provided as the reflective layer 7 in both the diffractive structure forming region 4 and the diffractive structure forming non-region 51 provided with the dielectric multilayer film layer 61 using a vacuum deposition method.

  Further, as the adhesive layer 8, a composition having the following blending ratio was applied by a gravure method at a coating thickness of 10 μm and a drying temperature of 110 ° C. to obtain a sticker-shaped anti-counterfeit medium.

(Adhesive layer)
20 parts acrylic resin
5 parts vinyl chloride vinyl acetate copolymer resin
50 parts of toluene
50 parts of methyl ethyl ketone

  This sticker-shaped anti-counterfeit medium was affixed to a card that requires authenticity determination to obtain a card with an anti-counterfeit medium.

<Comparative Example (Configuration not having a dielectric multilayer film layer)>
An anti-counterfeit medium sticker having the following configuration was formed on one side of a support made of a transparent polyethylene terephthalate film having a thickness of 25 μm.

  First, as a diffractive structure forming layer, a composition having the following blending ratio is applied by a gravure printing method at a coating thickness of 1 μm and a drying temperature of 110 ° C., and a diffractive structure relief pattern is formed in a part of the region by roll embossing. did. Here, the diffracted light from the diffractive structure forming region 4 is observed when observed from 0 ° to 45 ° when the direction perpendicular to the anti-counterfeit medium plane is 0 ° and the parallel direction is 90 °. Only designed so that the pattern by diffracted light can be observed.

(Diffraction structure forming layer)
Mixture of vinyl chloride-vinyl acetate copolymer and urethane resin 25 parts methyl ethyl ketone 70 parts toluene 30 parts

  Furthermore, an Al layer having a thickness of 50 nm was provided as a reflective layer in both the diffractive structure formation region and the diffractive structure non-formation region using a vacuum deposition method.

  Further, as a bonding layer, a composition having the following blending ratio was applied by a gravure method at a coating thickness of 10 μm and a drying temperature of 110 ° C. to form a sticker-shaped anti-counterfeit medium.

(Adhesive layer)
20 parts acrylic resin
5 parts vinyl chloride vinyl acetate copolymer resin
50 parts of toluene
50 parts of methyl ethyl ketone

  This sticker-shaped anti-counterfeit medium was affixed to a card that requires authenticity determination to obtain a card with an anti-counterfeit medium.

  The reflected light when white light was irradiated to the forgery prevention medium part of the card | curd with the forgery prevention medium of the produced Example and a comparative example was observed. In the example, when the angle perpendicular to the anti-counterfeit medium plane is 0 ° and the parallel direction is 90 °, the observation from 0 ° to 45 ° is the same as the comparative example. On the other hand, when observed at an angle of 45 ° to 90 ° at which the relief pattern due to diffracted light is not visible, unlike the comparative example, in the example, the region where the diffraction structure relief pattern is not formed is changed to red. I was able to observe.

  As described above, according to the present invention, in the anti-counterfeit medium combining the diffractive structure and the structure having a color change effect different from the above, the optical effects are not mixed with each other, and it is easy to determine the authenticity. A high anti-counterfeit medium can be produced.

DESCRIPTION OF SYMBOLS 11, 12, 13 ... Anti-counterfeit medium 14 ... Sticker-form anti-counterfeit medium 15 ... Transfer foil-shaped anti-counterfeit medium 2 ... Support body 3 ... Diffraction structure formation layer 4 ... Diffraction structure formation area 41 ... Diffraction where an optical effect appeared Structure formation region 51 ... Diffraction structure non-formation region 52 provided with the dielectric multilayer film layer 61 ... Diffraction structure non-formation region 511 provided with the dielectric multilayer film layer 62 ... Color of the dielectric multilayer film layer 61 appeared Diffraction structure non-formation region 512... Diffraction structure non-formation region 521 where the dielectric multilayer film layer 61 appears transparent. Diffraction structure non-formation region 522 where the color of the dielectric multilayer film layer 62 appears... Diffractive structure non-formation region 53, which is visible, a diffractive structure non-formation region 61 in which no dielectric multilayer film layer is provided, a dielectric multilayer film layer 611 satisfying Equation 1, an optical interference wavelength range 62 represented by Equation 1, and Equation 2. Filling dielectric Somakuso 621 ... optical interference wavelength range 7 shows the expression 2 ... reflective layer 8 ... adhesive layer 9 ... peeling protective layer

Claims (4)

  An anti-counterfeit medium comprising a color change effect layer having a diffractive structure formation region and a diffractive structure non-formation region on a support, wherein the diffractive structure non-formation region exhibits a color change effect in a visible light region.   2. The medium for preventing forgery according to claim 1, wherein the color change effect layer is made of a dielectric multilayer film.   The anti-counterfeit medium according to claim 2, wherein the interference light obtained by the dielectric multilayer film changes into visible light and invisible light depending on a viewing angle.   The anti-counterfeit medium according to claim 1 or 2, further comprising a reflective layer in the diffraction structure formation region and / or the diffraction structure non-formation region.