JP2010005796A - Authenticity identification element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of an authenticity identification element comprised of a lamination of a cholesteric liquid crystal and a relief hologram, wherein visibility and identifiability of the cholesteric liquid crystal are deteriorated by the reflected light by from a reflective thin film formed by the relief hologram, making it difficult to detect the authenticity identification element. <P>SOLUTION: The authenticity identification element A includes a black color pattern layer 5 to absorb unnecessary reflective light, which is located between the relief hologram and the reflective thin film 3 formed thereon and in an opposite position to the cholesteric liquid crystal 4, thereby improving the visibility of the cholesteric liquid crystal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an authenticity identifier that makes it possible to distinguish between an object obtained by forgery or falsification based on an unauthorized intention and an authentic object. The present invention also relates to a product in which such an authenticity identifier is processed into a label form or transfer sheet form suitable for application to an article.

  In the present specification, “part” indicating the formulation is based on mass. The “hologram” includes a hologram and a hologram having a light diffractive function such as a diffraction grating.

  (Main use) The main use of the hologram sheet of the present invention is a hologram sheet used in the field of anti-counterfeiting. Specifically, when used as a counterfeit such as a credit card, the card holder That may cause damage to the credit card company, driver's license, employee ID card, membership card, ID card, entrance examination voucher, passport, banknote, gift certificate, point card, stock certificate, securities, lottery ticket There are horse tickets, bankbooks, boarding tickets, pass tickets, air tickets, admission tickets for various events, play tickets, prepaid cards for public transportation and public telephones.

Each of these is an information recording body that holds information having economic or social value, and it is desirable to have a function that can identify the authenticity of the recording body for the purpose of preventing damage caused by forgery. .

In addition to these information recording media, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage of such expensive products. Boxes and cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.

Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.

(Background technology)
Conventionally, for the purpose of preventing forgery of information recording bodies and the above-mentioned various articles (collectively referred to as authenticity identification objects), it is said that they have manufacturing difficulties due to the precision of their structures. Often, holograms are applied as authenticity distinguishable. However, since the hologram manufacturing method itself is known and can be precisely processed by that method, when the hologram is merely for visual judgment, there is no difference between a genuine hologram and a forged hologram. It is difficult to distinguish.

  These authentic identification objects, in particular, articles that have been subjected to hologram images in a label form or transfer form, are not only used for authentic identification of visual confirmation of hologram images, but also by using a new authenticity identification method. There is a need to identify the authenticity of.

(Prior art)
In order to meet these requirements, an authenticity discriminator having a light selective reflection layer that is laminated on a hologram and reflects only one of the left-handed polarized light and the right-handed polarized light in the incident light is proposed. It was. (For example, refer to Patent Document 1.)
As this light selective reflection layer, cholesteric liquid crystal is used, and the anti-counterfeiting property is enhanced by a method of confirming using a polarizing plate or the like.

However, as described in Patent Document 1, since the reflectance of the reflective thin film layer on the hologram forming layer is high, the light that is transmitted without being reflected by the cholesteric liquid crystal layer (complementary light of selective reflected light) Reflecting on the reflective thin film layer and returning to the cholesteric liquid crystal layer again (hereinafter referred to as return light), this return light becomes a noise component when observing the cholesteric liquid crystal and is added to and mixed with the selectively reflected light. However, the color tone was not the original color of the liquid crystal, and it was even difficult to see and identify.

For this reason, in Patent Document 1, a contrivance is made such that the reflective thin film layer is partially formed or removed, and the liquid crystal layer is visually recognized in a portion that is not formed or removed. In this formation or partial removal method, a thin film is formed through a pattern mask having a shielding portion and an opening, and a thin film is not formed on a substrate in a portion having the shielding portion, or a water-soluble resin pattern is used. Utilizing this method, a reflective thin film layer is formed on the entire surface of the substrate including the water-soluble resin pattern, and only the portion with the water-soluble resin pattern is removed with an aqueous solution, etc., and the reflective thin film layer is patterned. It is shown.

The former places a pattern mask on the substrate, forms a thin film from the pattern mask to the substrate, forms a thin film only at the opening of the pattern mask, and then removes the pattern mask to form a partial thin film. However, there are disadvantages in that not only the pattern mask creation work and its installation / removal work are complicated, but also the pattern position accuracy is insufficient.

In the latter, pattern printing is performed with a water-soluble ink in which a water-soluble resin or a water-swellable resin is dissolved or dispersed in a portion to be removed, and a reflective thin film layer is formed on the entire surface, and then water, acid or alkaline is formed on the surface. The water-soluble resin pattern is removed by contacting with an aqueous solution, and the reflective thin film layer where the water-soluble resin pattern is laminated is removed, thereby reflecting the portion where the water-soluble resin pattern is not laminated. The reflective thin film layer is formed in a pattern while leaving the conductive thin film layer, and the operation is very complicated.

  Furthermore, a method of absorbing the complementary color light by, for example, providing an adhesive layer containing a black dye in a portion from which the reflective thin film layer has been removed has been proposed, but at the interface between the transparent resin layer and the adhesive layer. The complementary color light causes interface reflection, and has a disadvantage that the reflected light reduction effect due to light absorption by the black dye cannot be sufficiently exhibited. Moreover, the light absorptivity of the black dye does not cover the entire visible light region. Accordingly, even if the reflective thin film layer is removed, the complementary color light is still reflected, and the visibility of the cholesteric liquid crystal layer is lowered.

JP 2007-90538 A

  Accordingly, the present invention has been made to solve such problems. The purpose is to provide an authenticity discriminator that is easy to discriminate authenticity with little deterioration of the discriminability of the cholesteric liquid crystal layer due to the lamination of the cholesteric liquid crystal layer and the hologram forming layer.

To solve the above problem,
In a first aspect of the authenticity identifier of the present invention, a transparent resin layer having a cholesteric liquid crystal layer provided on at least a part of one surface of a transparent substrate and having a hologram relief on the other surface of the transparent substrate. A black pattern layer having a refractive index difference of 0.05 or less with respect to the transparent resin layer is provided at least at a position corresponding to the cholesteric liquid crystal layer on a part of the hologram relief; A reflective thin film layer is provided so as to contact the layer and the hologram relief.

According to the authenticity identifier of the first aspect,
A black pattern layer is provided between the transparent resin layer having the hologram relief and the reflective thin film layer, at least at a position opposite to the cholesteric liquid crystal layer, so that it enters the cholesteric liquid crystal for observation. Of the light (observation light), predetermined light is first reflected by this liquid crystal layer (selective reflected light), and other light (light that is complementary to the reflected light and complementary color light) is this liquid crystal layer. Passes through the reflective thin film layer and is totally reflected by this layer, but only the portion where the black pattern layer is provided absorbs the complementary color light over the entire wavelength range. Since it does not reach the reflective thin film layer and does not generate unnecessary reflected light (hereinafter also referred to as noise), only the original selectively reflected light reflected from the cholesteric liquid crystal layer is seen from the observation side. Is observation, its presence can be easily identified accurately.

  Such a black pattern layer uses a pigment having absorptivity for the entire wavelength region of light to be observed (visible light) such as fine-particle carbon black. On the other hand, the black dye partially loses its absorbency due to the light absorption characteristic depending on the dye structure, and the light absorption characteristic itself is weak. In order to completely absorb the complementary color light, the thickness of the black layer is not sufficient. It was necessary to increase the thickness considerably.

  In addition, since the transparent resin layer and the resin constituting the pressure-sensitive adhesive layer are usually used in different resin systems, interfacial reflection occurs at the interface. This interfacial reflection occurs when there is a difference in the refractive index of the layers in contact (occurs even with a difference of 0.01), and the greater the difference in the refractive index, the stronger the reflection (a difference of 0.05 or more reflects fairly strongly). At the same time, since the intensity varies depending on the incident wavelength, this interface reflection also becomes a noise component when observing the cholesteric liquid crystal.

Therefore, for the black pattern layer, a resin having a refractive index similar to that of the transparent resin layer having a hologram relief, using a black pigment such as a fine particle carbon blank having no wavelength dependency in light absorption. (Refractive index difference is within 0.05). As a result, interface reflection at the interface between the two layers can be suppressed, noise components when observing the cholesteric liquid crystal can be eliminated, and as a result, visibility can be improved.

  As the transparent resin layer, a thermoplastic resin such as acrylic or a thermosetting resin such as epoxy-modified unsaturated polyester resin is used. Therefore, the resin used for the black pattern layer is the same as those resins. As described above, the refractive index difference can be suppressed to within 0.05, and the adhesion between the layers can be ensured. Even in other resin systems, the same effect can be obtained by selecting the two points with attention.

  As the carbon black, those having remarkably blackness and colorability such as fine carbon black such as channel black and furnace black are used rather than lamp black and bone black. Furnace black is particularly preferred because its surface is inert and stable. A particle size of about 0.01 to 0.1 μm is usually used, and about 10 to 50% is added to the resin and sufficiently dispersed.

  The method for forming the black pattern layer does not require a complicated operation such as partial removal of the thin film described above, and an appropriate method can be used for the formation pattern, such as an offset printing method or a gravure printing method. However, it is desirable to use the same formation method as that of the cholesteric liquid crystal layer in the sense that the position is matched (also referred to as tuning) with the formation pattern of the cholesteric liquid crystal layer. Furthermore, a flexographic printing method can be used in order to make the formation thickness relatively thick and suppress bleeding and ink sag. The thickness to be formed is adjusted by the characteristics of carbon black to be used and the amount added, but is usually about 2 to 20 μm.

Further, according to a second aspect of the authenticity identifier of the present invention, the surface of the black pattern layer is a rough surface, and a portion of the reflective thin film layer that is in contact with the surface follows the rough surface. It is characterized by.
According to the authenticity identifier of the second aspect, the surface of the reflective thin film layer in contact with the black pattern layer is a rough surface, and the light that has been transmitted without being absorbed by the black pattern layer is reflected among the complementary color light. Can be scattered without being totally reflected on the surface of the conductive thin film. This can further reduce noise and, as a result, improve visibility. The rough surface means that the cross-sectional shape is irregular irregularities, and thus the light reflected by the surface becomes scattered light.

  As a method of roughening the black pattern layer, a method of roughening using the black pattern forming method and a method of increasing the pigment size to be used may cause the pigment to push up or jump out of the surface of the black pattern layer. There is a method to roughen the surface. As a method using the forming method, there is a method of performing embossing having a rough surface pattern after pattern formation or roughening a mesh used in silk screen printing. As a method for increasing the pigment size, if the size of carbon black and other extender pigments is about the thickness of the black pattern layer, after the black pattern is formed, the pigment protrudes from the formation surface to become a rough surface.

According to a third aspect of the authenticity identifier of the present invention, the black pattern layer has carbon black having a particle diameter of 1.0 μm or more.
According to the authenticity identifier of the third aspect, by making the carbon black particle size 10 to 100 times the normal, it is possible to increase the absorption of incident light, and at the same time, this black pattern and its The interface shape with the thin film reflective layer formed on the top can be roughened, and the reflection at the interface between the black pattern layer and the thin film forming layer as well as the interface between the transparent resin layer and the black pattern layer can be suppressed. be able to.

As the carbon black, self-dispersing carbon black having a particle size of 1 to 10 μm is used. When this carbon black is dispersed in the resin or the like, the surface roughness of the interface becomes a surface having the same level as the particle size, and interface reflection can be greatly limited.
In any embodiment, the constituent order of the layers may be a transparent base material, a cholesteric liquid crystal, a hologram forming layer, and a reflective thin film layer.

  According to the authenticity identifier of the present invention, there is provided an authenticity identifier that is easy to identify authenticity with little deterioration of the distinguishability of the cholesteric liquid crystal layer due to the lamination of the cholesteric liquid crystal layer and the hologram forming layer. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of an authenticator A showing one embodiment of the present invention.
FIG. 2 is a cross-sectional view of an authenticator A ′ showing another embodiment of the present invention.

  (Transparent Substrate) The transparent substrate 1 used in the present invention can be reduced in thickness, and can withstand mechanical strength and processing when manufacturing authenticity identifiers A and A ′. Those having solvent resistance and heat resistance are preferred. Since it depends on the purpose of use, it is not limited, but a film-like or sheet-like plastic is preferable.

For example, various plastic films such as polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polysulfone, polyethylene, polypropylene, polystyrene, polyarylate, triacetyl cellulose (TAC), diacetyl cellulose, and polyethylene / vinyl alcohol can be exemplified. .
The thickness of the transparent substrate 1 is usually 5 to 250 μm, but when considering the sneak light from the reflective thin film layer 3, it is preferably 5 to 50 μm, particularly 5 to 25 μm.

  (Transparent resin layer having hologram relief: also referred to as hologram forming layer) As the transparent resin material for constituting the hologram forming layer 2 of the present invention, various thermoplastic resins, thermosetting resins, or ionizing radiation curing are used. Can be used. Thermoplastic resins include acrylic ester resins, acrylamide resins, nitrocellulose resins, or polystyrene resins. Thermosetting resins include unsaturated polyester resins, acrylic urethane resins, epoxy-modified acrylic resins, and epoxy-modified unsaturated resins. A polyester resin, an alkyd resin, a phenol resin, etc. are mentioned.

These thermoplastic resins and thermosetting resins can be used alone or in combination of two or more. One or more of these resins may be cross-linked using various isocyanate resins, or various curing catalysts, for example, metal soap such as cobalt naphthenate or zinc naphthenate may be blended. Or peroxide such as benzoyl peroxide and methyl ethyl ketone peroxide for initiating polymerization with heat or ultraviolet light, benzophenone, acetophenone, anthraquinone, naphthoquinone, azobisisobutyronitrile, or diphenyl sulfide good.

Examples of the ionizing radiation curable resin include epoxy acrylate, urethane acrylate, acrylic-modified polyester, etc., for the purpose of introducing a crosslinked structure into such an ionizing radiation curable resin or adjusting the viscosity, A monofunctional monomer, a polyfunctional monomer, or an oligomer may be blended and used.

In order to form the hologram forming layer 2 using the above resin material, it can be directly formed by developing the photosensitive resin material by performing interference exposure of the hologram. It is preferable to perform molding by using a replica or a plating mold thereof as a replica mold and pressing the mold surface against the layer of the resin material.

When thermosetting resin or ionizing radiation curable resin is used, curing is performed by heating or ionizing radiation irradiation while keeping the uncured resin in close contact with the mold surface, and then cured by peeling after curing. The fine irregularities of the relief hologram can be formed on one side of the layer made of a transparent resin material. A diffraction grating forming layer having a diffraction grating formed in a pattern by a similar method can also be used as the optical diffraction structure.

  A hologram is a recording of interference fringes due to interference of light between object light and reference light in an uneven relief shape. For example, a laser reproduction hologram such as a Fresnel hologram, a white light reproduction hologram such as a rainbow hologram, There are color holograms utilizing the above principle, computer generated holograms (CGH), holographic diffraction gratings and the like. Further, like a machine readable hologram, the reproduction light may be converted into data by a light receiving unit and transmitted as predetermined information, or authenticity determination may be performed.

In order to precisely create fine irregularities, not only optical methods, but also electron beam lithography equipment can be used to create precisely designed relief structures that produce more precise and complex reproduction light. Good. The relief shape is designed to have a pitch, depth, or specific periodic shape of the unevenness according to the wavelength (range) of the light or light source for reproducing or reproducing the hologram, the direction and the intensity of reproduction or reproduction. The pitch (period) of the unevenness depends on the reproduction or reproduction angle, but is usually 0.1 μm to several μm, and the depth of the unevenness is a factor that greatly affects the reproduction or reproduction intensity, but is usually 0.1 μm. ˜1 μm.

As in the case of a single diffraction grating, when the unevenness of exactly the same shape is repeated, the more the adjacent unevenness is the same, the greater the intensity of interference of the reflected light and the stronger the intensity. Converge. The blur in the diffraction direction is also minimized. When the individual points of the image converge to the focal point, such as a stereoscopic image, the convergence accuracy to the focal point is improved, and the reproduced or reproduced image becomes clear.
Furthermore, in the case of a transparent metal compound thin film, the upper and lower surfaces of the thin film have the same relief shape, and the more uniform the distance between the surfaces (that is, the film thickness), the higher the reproduction or reproduction strength. growing.

  The hologram relief shape is shaped (also referred to as replication) by using an original plate on which diffraction gratings and interference fringes are recorded in a concavo-convex shape as a press die (referred to as a stamper), and the transparent substrate 1 and the reflective thin film layer 3. The uneven pattern of the original plate can be duplicated by superimposing the original plate on top of each other and heat-pressing both of them with an appropriate means such as a heating roll. The hologram pattern to be formed may be single or plural.

In order to accurately reproduce the above-mentioned extremely fine shape and to minimize distortion and deformation such as heat shrinkage after replication, the original plate is made of metal and replicated at low temperature and high pressure.
For the original plate, a metal having high hardness such as Ni is used. After a Cr or Ni thin film layer is formed on the surface of a glass master or the like formed by optical imaging or electron beam drawing or the like by vacuum deposition or sputtering, Ni or the like is electrodeposited (electroplating, electroless plating) Further, it can be made by peeling the metal after forming 50 to 1000 μm by composite plating or the like.

The duplication method uses a flat plate type or a rotary type, the linear pressure is 0.1 ton / m to 10 ton / m, and the duplication temperature is usually 60 ° C. to 200 ° C.

(Reflective thin film layer) In the present invention, the reflective thin film layer 3 is formed on the hologram relief surface of the hologram forming layer 2. Since this thin film layer needs to reflect incident light, it is not particularly limited as long as it is a thin film layer having a higher refractive index than that of the hologram forming layer 2.
The reflective thin film layer 3 may be either a metallic glossy reflective layer such as a metal thin film formed by a vacuum thin film method or the like, or a transparent reflective layer. When provided, it is preferable because the design of the authenticity identification object can be confirmed through the transparent reflective layer.

As a transparent reflective layer, since the optical refractive index is different from that of the hologram forming layer 2 with a substantially colorless and transparent hue, it is possible to visually recognize the glitter of a hologram or the like even though there is no metallic luster, A transparent hologram can be produced. For example, a thin film having a higher refractive index than that of the hologram forming layer 2, such as ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂ S ₃ , SiO, SnO ₂ , ITO, and the like are available.

Preferably, it is a metal oxide or nitride, specifically, Be, Mg, Ca, Cr, Mn, Cu, Ag, Al, Sn, In, Te, Ti, Fe, Co, Zn, Ge, Pb. Cd, Bi, Se, Ga, Rb, Sb, Pb, Ni, Sr, Ba, La, Ce, Au, and other oxides or nitrides, and the like can be exemplified by a mixture of two or more thereof. Also, a general light-reflective metal thin film such as aluminum can be used as a transparent reflective layer when it has a thickness of 20 nm or less and becomes transparent.

  The transparent metal compound is formed on the hologram relief surface of the hologram forming layer 2 by vapor deposition, sputtering, ion plating, CVD (to the thickness of about 10 to 2000 nm, preferably 20 to 1000 nm, similarly to the metal thin film. It may be provided by a vacuum thin film method such as a chemical vapor deposition method.

  (Cholesteric Liquid Crystal) The cholesteric liquid crystal layer 4 used in the present invention is only required to have light selective reflectivity, and further, either left circularly polarized light or right circularly polarized light is applied to incident light from the observation side. It may have light selective reflectivity to reflect. Also, by applying these in combination, the determination method can be complicated, and a more sophisticated authenticity identifier can be obtained.

Cholesteric liquid crystals include cholesterol halides, monocarboxylic acid cholesterol esters, monocarboxylic acid sitosterol esters, benzoic acid derivative cholestanol esters, dibasic acid dicholesteryl esters, main chain liquid crystal polymer compounds, side chain liquid crystal polymers Examples thereof include molecular compounds and rigid main chain type liquid crystal polymer compounds.

More specifically, for example, cholesteryl chloride, cholesteryl acetate, cholesteryl nonanoate, methyl carbonate, ethyl cholesterol, cholesteryl p-methoxybenzoate, sitosteroyl benzoate, sitosteroyl p-methyl benzoate, cholestanyl benzoate, 10, 12- Docosadiin dicarboxylic acid dicholesteryl ester, 8,12-eicosadicarboxylic acid dicholesteryl ester, 10,12-pentacosadiin dicarboxylic acid dicholesteryl ester, dodecadicarboxylic acid dicholesteryl ester, 12,14-hexacosadiin dicarboxylic acid Dicholesteryl ester, 4- (7-cholesteryloxycarbonylheptyloxy) phenoxyoctanoic acid cholesteryl ester, L-glu Min acid -γ- benzyl / L-glutamate -γ- dodecyl copolymers and the like.

Further, cholesteryl formate, cholesteryl acetate, cholesteryl propionate, cholesteryl butyrate, cholesteryl pentanate, cholesteryl hexanate, cholesteryl heptanoate, cholesteryl octanate, cholesteryl nonanoate, cholesteryl decanate, cholesteryl decanate (cholesteryl laurate) Cholesteryl myristate, cholesteryl palmitate, cholesteryl stearate, cholesteryl oleate, cholesteryl oleyl carbonate, cholesteryl linoleate, cholesteryl 12-hydroxystearate, cholesteryl mercaptan, cholesterol chloride, cholesteryl fluoride, cholesteryl bromide, cholesteryl iodide, etc. Can be mentioned.

Preferably, a mixture of three kinds of alkylcholesterol (for example, cholesterol nanoate) and cholesteryl halide (for example, cholesterol chloride) cholesteryl oleyl carbonate is used, and these three types of liquid crystals are used so as to be used at room temperature. Is common.
In addition, it is not limited to the compound shown here, Moreover, these cholesteric liquid crystal compounds can be used 1 type or in mixture of 2 or more types.

As a liquid crystal compound in which a chiral compound is added to a nematic liquid crystal compound, 4-substituted benzoic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted phenyl ester, 4-substituted cyclohexane Carboxylic acid 4′-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4′-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4′-substituted phenyl ester, 4- (4- Substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4'-substituted cyclohexane, 2- (4-substituted phenyl) -5-substituted pyridine For example, “Palio Color LC242” ( ASF Co., Ltd.) and the like are used.

Particularly preferably, a liquid crystal compound having a cyano group or a fluorine atom at least at one end of the molecule is used, and various suitable chiral agents are added to these liquid crystal compounds. As the chiral compound, “CB-15”, “C-15” (manufactured by BDH), “CM-21”, “CM-22”, “CM-19”, “CM-20”, “CM” (Above, manufactured by Chisso Corporation), "S1082", "S-811", "R-811" (above, manufactured by Merck), "Palio Color LC756" (produced by BASF), and the like.

Further, a cholesteric liquid crystal having no cholesterol group in which a group having an asymmetric carbon is introduced into a terminal group of a nematic liquid crystal obtained by organic synthesis, or a mixed liquid crystal in which a Schiff nematic liquid crystal is added to a cholesterol derivative is also used. Furthermore, halogen substitution products and esterified products of natural cholesterol (cholesteryl benzoate, cholesteryl chloride, cholesteryl oleate, cholesteryl nonanoate, and the like are also suitable.

As a method for providing these cholesteric liquid crystals, they can be formed using a normal printing method or coating method as a solvent-based, water-based, or solvent-free system. More preferably, by using the same means as the method for forming the black pattern layer, the synchronism of the formation position can be enhanced. When the same pattern is formed, the plate making method can be the same. In particular, after the black pattern layer is provided on the transparent substrate, this position can be used as a timing mark (print positioning mark) to form a liquid crystal layer or to reproduce a hologram relief.

  Alternatively, the liquid crystal may be formed using an ink encapsulated with a resin film such as gelatin. The encapsulated product has excellent physical properties (toughness, wear resistance, heat resistance, etc.) as well as workability at the time of manufacture, and prevents problems such as liquid seepage, and is used in the present invention. It is particularly suitable for the required hygiene.

  The shape and thickness of the cholesteric liquid crystal layer 4 need to be appropriately optimized according to the purpose of use of the authenticity identifier. Furthermore, since it can be set to several tens of μm as a hidden character like a micro character, the thickness corresponding to each individual, that is, from several μm to 50 μm, while maintaining selective reflectivity, It shall be optimal.

  When the cholesteric liquid crystal layer 4 is provided, an alignment treatment such as providing the following alignment film may be performed in advance. Any alignment film may be used as long as it can be generally used as an alignment film, such as polyvinyl alcohol resin (PVA) or polyimide resin. The alignment film is formed by applying a solvent solution of these resins to the surface of the layer forming the cholesteric liquid crystal layer 4 by an appropriate application method and drying, followed by rubbing with a cloth, a brush, or the like. To do.

(Black Pattern Layer) In the present invention, the black pattern layer 5 is formed on the hologram relief surface of the hologram forming layer 2 at a position at least facing the cholesteric liquid crystal layer 4.
In order not to generate interface reflection between the hologram forming layer 2 and the black pattern layer 5, the same resin is used for the resin layers constituting the hologram forming layer 2 and the black pattern layer 5, or the same resin or other resin is used. Even those resins having the same refractive index or a difference within 0.05 are used.

  That is, polymethyl methacrylate (refractive index n = 1.49), polymethyl acrylate (n = 1.47), polybenzyl methacrylate (n = 1.57), polybutyl acrylate (n = 1.44), polyisobutyl Acrylate (n = 1.48), cellulose nitrate (n = 1.54), methylcellulose (n = 1.50), cellulose acetate propionate (n = 1.47), polystyrene (n = 1.60) , Polyethylene terephthalate (n = 1.64), polyvinyl acetate (n = 1.47), polyvinyl chloride / vinyl acetate (n = 1.54), melamine resin (n = 1.56), epoxy resin (n = 1.61), phenol resin (n = 1.60), etc., or a mixture thereof can be used as appropriate.

As the black pigment, any pigment can be used as long as it has an absorptivity for the entire wavelength region of light to be observed (visible light). Typically, fine carbon black can be used.
Carbon black includes Mitsubishi Chemical HCF2400B, HCF2700B, MCF900, RCF45, etc., Degussa Evonik Color Black FW200, Special Black 250, Asahi Carbon Sun Black 700, Sun Black 900, Ketjen Black EC-600 Etc. can be used.

  A particle size of 0.01 to 0.1 μm is preferable, but secondary aggregation tends to occur, and redispersion treatment or the like needs to be performed. The addition amount is determined by the balance with the thickness formed by an appropriate formation pattern formation method such as an offset printing method, a gravure printing method, etc., but usually 10% to 50% addition is preferable, dissolved in an appropriate solvent, It is formed to a thickness of 2 to 20 μm.

  After the black pattern is formed, the surface of the black pattern can be roughened by heating and pressing with a metal stamper having irregularities with a surface roughness of 1.0 μm or more. In addition to this black pigment, the black pattern layer can also be roughened by using extender pigments such as calcium carbonate and titanium dioxide having a particle size of 1.0 μm or more.

  However, the carbon black used in the third embodiment of the authenticity identifier of the present invention is agglomerated and has a particle size of 1 μm or more, such as hydrophilic aqua black 162, aqua black 0001, etc. manufactured by Tokai Carbon Co., Ltd. That is suitable. As the resin system and the forming method used, those described above can be used. However, the effect of roughening can be enhanced by making the formation thickness equal to the grain size to be employed, or thinner.

Further, the authenticity identification body of the present invention can be further labeled with a pressure-sensitive adhesive or a transfer sheet by applying an adhesive.
In this case, as the pressure-sensitive adhesive, any conventionally known solvent-based or water-based pressure-sensitive adhesives such as vinyl acetate resin, acrylic resin, vinyl acetate-acrylic copolymer, vinyl acetate-vinyl chloride copolymer, ethylene-acetic acid are used. Examples include vinyl copolymers, polyurethane resins, and rubber resins such as natural rubber and chloroprene rubber.

Natural latex such as natural rubber latex, natural rubber latex obtained by graft polymerization of natural rubber with styrene, especially methacrylic acid methyl, in particular, to make natural material composition What was produced from the raw material may be used and formation thickness, a formation method, etc. are selected suitably.

Moreover, as an adhesive agent, since it is for ensuring the adhesiveness with respect to various articles | goods, what has good adhesiveness with the reflective thin film layer 4, and can adhere | attach an adherend firmly. preferable. Specific examples include vinyl chloride resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymer resins, acrylic resins, polyester resins, polyurethane resins, polyamide resins, and rubber-modified products. Appropriately selected from the above can be used, and these can be used alone or in a mixture of two or more, and if necessary, hard resin, plasticizer, and other additives can be added and used. The formation thickness, the formation method, and the like are appropriately selected.

Example 1
As a transparent substrate 1, a cholestic liquid crystal layer 4 having a thickness of 5 μm was formed in a “H letter” shape by gravure printing on the surface of a 25 μm PET film, and then cured with ultraviolet rays.
・ <Cholesteric liquid crystal composition>
Bicolor LC242 37 parts by weight Bicolor LC756 2 parts by weight UV polymerization initiator 1 part by weight Toluene 60 parts by weight

Applying a melamine resin composition (n = 1.56) to the surface of the PET film opposite to the surface on which the above printing has been performed, and heat curing the mold surface of the relief hologram duplication mold in contact. Thus, a relief hologram was formed, and a hologram forming layer 2 having a thickness of 20 μm was obtained. A black pattern layer 4 having a thickness of 5 μm was obtained by using the same gravure method and the same gravure plate as the black pattern layer 4 having the following composition.

・ <Black pattern composition>
30 parts by mass of the melamine resin Toka Black 8500 10 parts by mass extender pigment 5 parts by mass toluene 55 parts by mass

On the surface on which the relief hologram is shaped and on the surface of the black pattern layer 4, AL is vacuum-deposited to form the reflective thin film layer 3 having a thickness of 100 nm, thereby obtaining the authenticator A for authenticity determination.

When the obtained authenticity identifier is viewed from the observation side, the hologram reproduction image and the letter “H” in the black pattern layer are seen. When the observation angle is changed, the black pattern letter “H” changes to “green”. It was clearly recognized.

(Example 2)
Example 2 was obtained in the same manner as in Example 1 except that the same amount of calcium carbonate having an average particle diameter of 1.0 μm was used as the extender pigment. When the obtained authenticity identifier is viewed from the observation side, the hologram reproduction image and the black pattern letter “H” can be seen, and when the observation angle is changed, the black pattern letter “H” changes to “green”, clearly I was able to recognize. In particular, the color was shown to every corner of the letter “H”, and no reflected light from the reflective thin film layer was seen.

(Example 3)
Polymethyl methacrylate (n = 1.49) is used for the hologram forming layer 2, polymethyl methacrylate (n = 1.49) is also used for the black pattern layer 5, and glassy carbon manufactured by Tokai Carbon Co., Ltd. is used as carbon black. Example 3 was obtained in the same manner as in Example 1 except that the particle diameter was 1.0 μm and the formation thickness was 1.0 μm. When the obtained authenticity identifier is viewed from the observation side, the hologram reproduction image and the black pattern letter “H” can be seen, and when the observation angle is changed, the black pattern letter “H” changes to “green”, clearly I was able to recognize. In particular, the color “H” appears in every corner, and no reflected light from the interface reflection was observed.

(Comparative example)
A comparative example was obtained in the same manner as in Example 1 except that melamine resin (n = 1.56) was used for hologram forming layer 2 and polymethyl methacrylate (n = 1.49) was used for black pattern layer 5. It was. When the obtained authenticity identifier is viewed from the observation side, the hologram reproduction image and the black pattern letter “H” can be seen. When the observation angle is changed, the black pattern letter “H” is changed to “green”. , By return light. Every corner of the letter “H” was not clearly recognized.

It is sectional drawing of the authenticity identification body A which shows one Example of this invention. It is sectional drawing of authenticity identification body A 'which shows the other Example of this invention.

Explanation of symbols

A, A ′ Authenticity discriminator 1 Transparent substrate 2 Transparent resin layer having hologram relief (hologram forming layer)
3 Reflective thin film layer 4 Cholesteric liquid crystal layer 5 Black pattern layer 6 Roughened interface

Claims (3)

  A cholesteric liquid crystal layer is provided on at least a part of one surface of the transparent substrate, a transparent resin layer having a hologram relief on the other surface of the transparent substrate, and a part on the hologram relief, At least at a position facing the cholesteric liquid crystal layer, a black pattern layer having a refractive index difference of 0.05 or less with respect to the transparent resin layer is provided, and a reflective thin film layer is provided so as to be in contact with the black pattern layer and the hologram relief An authenticity identifier characterized by being provided.   2. The authenticity identifier according to claim 1, wherein the surface of the black pattern layer is a rough surface, and a portion of the reflective thin film layer that is in contact with the surface follows the rough surface.   The authenticity identifier according to claim 2, wherein the black pattern layer has carbon black having a particle size of 1.0 μm or more.

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