JP5012681B2 - Laminated body and method for producing the same - Google Patents

Description

  The present invention relates to a laminate including a retardation layer exhibiting birefringence and a method for producing the same.

  Conventionally, authentication methods such as cards and passports, and securities media such as gift certificates and stock certificates have been used by attaching a device that is difficult to counterfeit and visually or using a verifier. Yes. In recent years, the distribution of counterfeit products has become a problem, and in order to prevent such distribution, the use of technology equivalent to securities is increasing.

  The anti-counterfeiting technology includes a so-called overt technique in which a general user can recognize that the anti-counterfeiting technique is true, and a so-called covert technique in which only a specific user knows the existence of the anti-counterfeiting technique and can judge the authenticity.

  Representative examples of the overt technique include a diffractive structure forming body such as a hologram, and a multilayer interference film such as OVI (Optically Variable Ink). Representative examples of the covert technique include fluorescent printing, line latent images, and the like, and are often commercialized by combinations thereof.

Further, a method has been proposed in which a polarization latent image device in which a retardation layer having partially different slow axis angles is partially formed on a reflective layer is used as a covert technique. Although these devices cannot visually distinguish the angle of the slow axis, the transmittance varies partially depending on the angle formed by the transmission optical axis of the polarizing film and the slow axis of the retardation layer when observed through the polarizing film. This is a technology that makes latent images appear.
JP-A-8-15681

  However, in the above-described polarization latent image device, if the retardation value and slow axis direction of the substrate are not controlled, the latent image is disturbed and the contrast is lowered. Therefore, non-stretched or uniaxially stretched films are used as the substrate whose phase difference value and slow axis direction are controlled, but these films are vulnerable to physical stimuli such as heat and pressure, and transfer. Alternatively, there is a problem that wrinkles or breakage may occur due to stimulation such as bonding or forming a reflective layer or diffractive structure.

  The present invention has been made to solve the above-mentioned problems, and the problem is that in a laminate using, as a base material, an unstretched or uniaxially stretched film that is vulnerable to physical stimulation such as heat and pressure. It is an object of the present invention to provide a laminate that can be stably manufactured without wrinkling or breaking when transferring or adhering, or when forming a reflective layer or a diffractive structure, and a method for manufacturing the same.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a base material, a retardation layer having a slow axis in the planar direction of the base material, an adhesive layer made of ultraviolet light or an electron beam curable resin, and reflection. It becomes a laminated body characterized by laminating | transferring the transfer foil containing a layer and a peeling layer in this order.

  The invention according to claim 2 includes a base material, an adhesive layer made of an ultraviolet ray or an electron beam curable resin, a retardation layer having a slow axis in the plane direction of the base material, a reflective layer, and a release layer. The transfer foil is laminated in this order to obtain a laminated body.

  The invention according to claim 3 is the laminate according to claim 1 or 2, wherein the substrate does not have optical anisotropy.

  The invention according to claim 4 is the laminate according to claim 1 or 2, wherein the base material is a base material in which a slow axis direction and a retardation value are controlled.

  The invention according to claim 5 provides the laminate according to any one of claims 1 to 4, wherein the reflective layer has a diffractive structure.

  The invention according to claim 6 is the transfer foil according to any one of claims 1 to 5, wherein the transfer foil has the release layer as an outermost layer, and an adhesive layer is further laminated on the release layer side. It becomes a laminate.

  The invention according to claim 7 is a sheet in which the laminate according to any one of claims 1 to 6 is rolled into a paper material.

  The invention according to claim 8 is the step of forming a retardation layer having a slow axis in the planar direction of the substrate on the substrate, and one of the layer comprising the substrate and the retardation layer. A step of applying an adhesive layer comprising an ultraviolet ray or an electron beam curable resin to the surface, a step of bonding a transfer foil including a reflective layer, a release layer and a transfer substrate to the surface to which the adhesive layer is applied, and the adhesive layer Is a method for producing a laminate, comprising a step of curing the substrate using ultraviolet rays or an electron beam, and a step of peeling the transfer substrate.

  The invention according to claim 9 is a transfer surface of a transfer foil including a step of forming a retardation layer having a slow axis in the planar direction of the substrate on the substrate, and a reflective layer, a release layer, and a transfer substrate. A step of applying an adhesive layer made of ultraviolet or electron beam curable resin, a step of bonding the transfer foil to one surface of the substrate on which the retardation layer is formed via the adhesive layer, It becomes the manufacturing method of the laminated body characterized by including the process of hardening an contact bonding layer using an ultraviolet-ray or an electron beam, and the process of peeling this transfer base material.

  According to a tenth aspect of the present invention, there is provided a process for producing a transfer foil comprising at least a release layer, a reflective layer, and a retardation layer having a slow axis in the plane direction of the transfer substrate on the transfer substrate, A step of applying an adhesive layer made of ultraviolet or electron beam curable resin on the material, a step of attaching a transfer foil to the surface of the substrate on which the adhesive layer is applied, and the adhesive layer using ultraviolet rays or an electron beam. And a step of curing, and a step of peeling the transfer substrate.

  According to an eleventh aspect of the present invention, there is provided a process for producing a transfer foil comprising at least a release layer, a reflective layer, and a retardation layer having a slow axis in a plane direction of the transfer substrate on the transfer substrate; A step of applying an adhesive layer made of ultraviolet light or an electron beam curable resin to the transfer surface of the transfer foil, a step of bonding a substrate to the surface coated with the adhesive layer, and the adhesive layer using ultraviolet light or an electron beam. It becomes the manufacturing method of the laminated body including the process to harden | cure and the process to peel a transfer base material.

  The laminate and the method for producing the same in the present invention enable the formation of a reflective layer and a diffractive structure even on a controlled film that does not have a phase difference that is weak against physical stimuli such as heat and pressure. is there.

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

  FIG. 1 is a view showing a cross section of a base material on which a retardation layer is laminated and a transfer foil for bonding to the base material. FIG. 2 is a view showing a cross section of a transfer foil in which retardation layers are laminated and a base material on which the transfer foil is bonded. The retardation layer may be provided on the substrate side as shown in FIG. 1, or may be provided on the transfer foil side as shown in FIG. In addition, when providing a phase difference layer in the transfer foil side, it provides in the position which becomes a visual recognition side rather than a reflection layer after transfer. When the retardation layer is provided on the substrate side, it may be provided on either side of the substrate. FIG. 3 is a schematic view of a transfer processing machine used in the present invention.

The retardation layer is made of a birefringent material. A birefringent material is a material having a different refractive index depending on the axis. When light passes through a birefringent material, the extraordinary ray e (refractive index: n _e) that transmits a high slow axis refractive index and the ordinary ray o (refractive index n _o for transmitting a low fast axis refractive index ) Between the two. The difference in refractive index between the extraordinary ray and the ordinary ray is called a birefringence Δn, has a unique value for each substance, and is expressed by the following equation.
Δn ₌ n e -n _o

Further, the phase difference received by the light transmitted through the retardation layer is proportional to the optical path length d passing through the birefringent material as a phase difference value δ, and is expressed by the following equation.
δ = Δn · d

  The retardation value δ of the retardation layer has special optical characteristics when it is ½ of the wavelength λ of the transmitted light. The λ / 2 retardation layer inverts the transmitted straight line change around the slow axis. That is, when the angle between the slow axis and the polarized light is θ, the transmitted polarized light forms an angle of 2θ.

  Since the laminate of the present invention includes the reflective layer, light passes through the retardation layer twice, so that the retardation value is ½ of the transmission condition. If the direction of the phase axis is partially changed, the change transmitted through the retardation layer changes in different directions depending on the location. Therefore, if a polarizing filter is used, the latent image appears as bright and dark on the modified film, and authenticity determination can be performed.

  As the base material used in the present invention, a film or sheet-like material having no phase difference is desirable, but those having a phase difference can also be used if the phase difference value can be controlled. Moreover, a polarizer can also be used as a base material.

  As the base material having no phase difference, TAC film, acrylic film, glass plate, unstretched PET film, PP film, PE film, and the like can be used. Examples of the phase difference film include uniaxial and biaxially stretched PET films, PP films, PE films, polycarbonate films, cellophane films, X and Y cut quartz plates, and the like. Polarizer is a general term for devices with polarization dichroism. PVA is impregnated with iodine or dichroic dye, and stretched and oriented absorption polarizer or dichroic dye is oriented on the alignment film. Absorptive polarizer, reflective polarizer with cholesteric liquid crystal aligned on a substrate, reflective polarizer with a birefringent multilayer film (manufactured by 3M), formed into a lenticular lens shape with a Brewster angle A prism polarizer, a birefringent diffractive polarizer in which a birefringent substance is formed in a diffraction grating shape, a diffractive polarizer in which a groove of a diffractive structure is deeply formed, and the like can be used. In addition to this, any blocking that can separate or extract a specific polarization component by reflected light or transmitted light can be used, and the polarizer in the present invention can be obtained.

  The phase difference layer 12 can be produced by a method of cutting out a material having phase difference and bonding the material to the base material or the transfer foil, a method of aligning a liquid crystal material on an alignment film, or the like.

  As a method of aligning the liquid crystal material on the alignment film, a photo alignment method, a rubbing alignment method, an emboss alignment method, or the like can be used.

  The photo-alignment method is a method in which an alignment film is irradiated with light having anisotropy such as polarized light to induce rearrangement of molecules in the film and anisotropic chemical reaction. This utilizes the alignment of liquid crystal molecules. Photoalignment mechanisms include photoisomerization of azobenzene derivatives, photodimerization and crosslinking of derivatives such as cinnamic acid ester, coumarin, chalcone and benzophenone, and photolysis of polyimide and the like. An alignment film is obtained by directing polarized light in a direction in which the liquid crystal is to be aligned and exposing through a filter such as a photomask.

  The rubbing alignment method is a method of rubbing an alignment film produced by applying a polymer solution on a substrate with a cloth. The property of the alignment film surface changes in the rubbing direction and liquid crystal molecules are aligned in this direction. Is. For the alignment film, polyimide, PVA, or the like can be used. Examples of the method of partially changing the alignment include a method of rubbing in a direction in which the liquid crystal is to be aligned while sequentially switching the window opening mask.

  The emboss alignment method is a method of embossing fine grooves on a substrate by embossing, and aligning liquid crystals along the grooves. This method can be produced by drawing a striped pattern on a positive resist with an electron beam of XY scan and developing it to produce a concavo-convex shape and embossing this concavo-convex shape on a resin film.

  As a method for forming these alignment films on a substrate or a transfer foil, a known method such as a gravure coating method, a micro gravure coating method, a spin coating method, a melt extrusion method, or the like can be used.

  The liquid crystal applied on these alignment films may be a polymer having an alignment property or a monomer having a reactive functional group such as an acrylic group. As a method for forming a liquid crystal on the alignment film, a known method such as a gravure coating method or a micro gravure coating method is used, and coating is performed with a thickness having a retardation value of λ / 2. The coated liquid crystal can be oriented by heat treatment. The liquid crystal monomer having a reactive functional group is cured by electron beam, ultraviolet light or heat after alignment.

  Alternatively, an alignment film itself having birefringence may be used. In this case, the film thickness of the liquid crystal is controlled so that the sum of the retardation values of the alignment film and the liquid crystal becomes the design site. When the design value can be realized only with the alignment film, it is not necessary to apply liquid crystal.

  The transfer foil has a structure that is separated by peeling or cohesive failure in any layer located between the transfer substrate 21 and the reflective layer 23. In order to stably realize these separations, the base material may be subjected to a release treatment or a release layer 22 may be provided.

  The release layer can be made of acrylic, styrene, nitrified cotton, or the like, and can be formed using a known method such as a gravure coating method or a micro gravure coating method, as with other layers.

The reflective layer 23 can be made of metal or high refractive index ceramics. As the metal, in addition to metals such as Al, Sn, Ag, Cr, Ni, and Au, alloys such as Inconel, bronze, and aluminum bronze can be used. As the _ceramic, it can be used TiO 2, ZnS, a high refractive index material such as _Fe 2 _{O 3.} These materials are formed on the transfer substrate 21 to a thickness of about 10 nm to 100 nm using vapor deposition, sputtering, ion plating, or the like. Moreover, metal foil and a ceramic board can also be used as a material.

  Further, a diffractive structure may be formed in the reflective layer. Examples of the diffractive structure include a hologram and a diffraction grating. If it is difficult to form a diffractive structure directly on the substrate, a diffractive structure forming layer may be provided separately.

  For holograms, a relief-type master plate consisting of fine concavo-convex patterns is produced by an optical imaging method, and then a nickel-made press plate is produced by duplicating the concavo-convex pattern by electroplating from this master plate. Large-scale replication is possible by a method in which a plate is heated and pressed on a layer forming a hologram. This type of hologram is called a relief hologram.

  Diffractograms are different from holograms that shoot actual images, and a simple image of a grating image or dot matrix (pixelgram, etc.) is expressed by arranging multiple types of simple diffraction gratings in a small area as pixels. To do. An image using such a diffraction grating can also be mass-replicated in the same manner as a relief hologram.

  The reflective layer can also be provided in a pattern. For providing the pattern, pasta processing, water-washed light processing, laser processing, or the like is used.

  Embossing to form these reflective layers and diffractive structures is subject to great heat and pressure on the base material, so the unstretched or uniaxially stretched film used in this case cannot withstand, and thermal wrinkles or breakage may occur. It becomes unstable processing. Therefore, a laminated body can be stably produced by performing these processes on the transfer foil side.

  For the transfer, first, an adhesive layer 33 made of ultraviolet or electron beam curable resin is applied to either the base material side or the transfer foil side, the base material and the transfer foil are bonded together, and an ultraviolet lamp or an electron beam irradiator is used. Then, the transfer substrate is peeled off to obtain a laminate. By using UV or electron beam curable resin for the adhesive layer in this way, wrinkles and breakage did not occur in the unstretched or uniaxially stretched film that is weak against physical stimuli such as heat and pressure used for the substrate, and was stable. Processing can be performed.

  For the adhesive layer, it is preferable to use a radical polymerization type adhesive using a monomer or oligomer having an unsaturated bond such as ultraviolet ray or electron beam curable acrylate. It is also possible to use a living polymerization type adhesive using epoxy, oxetane, or the like. These adhesives are coated by a known coating method such as microgravure, gravure, flexo or the like to form an adhesive layer. The coating may be a pattern. Further, when a living polymerization type adhesive having a slow curing rate is used, the adhesive layer may be applied and then bonded after being irradiated with ultraviolet rays or an electron beam.

  By providing the adhesive layer 47 on the back surface of the laminate thus obtained, a sticker can be created. Moreover, it is possible to provide an anti-replacement function by cutting the base material or forming a brittle layer.

  Moreover, it is possible to produce a paper sheet by micro slitting the obtained laminated body and winding it with a window opening so that a part of the paper can be seen.

  The laminate, sticker, and interleaving paper obtained above can be used as a part of a security medium or a product package, and the retardation layer is formed so that the direction of the slow axis is different for each part. In this case, when a polarizing film is superimposed on a laminate, a sticker, or a paper sheet, a latent image appears, and it is possible to determine whether the article is a new product or a counterfeit product.

  A 16 μm thick PET film is coated with a release layer made of acrylic resin and a diffractive structure forming layer made of urethane resin to a thickness of 1 μm each by gravure coating, embossed with a diffractive structure image, and a 450 mm Al reflective layer is formed. A hologram transfer foil was obtained by vacuum deposition.

Further, on a TAC film having a thickness of 40 μm, a photo-alignment agent IA-01 (manufactured by Dainippon Ink & Chemicals, Inc.) is coated with a thickness of 0.1 μm by using a micro gravure coating method to form a photo-alignment film. Formed. Wavelength using the a 365nm linearly polarized light, post exposure dose of the entire surface 1 J / cm ^2, and pattern exposure with irradiation dose of 1 J / cm ² through a photomask. A UV curable liquid crystal UCL-008 (manufactured by Dainippon Ink & Chemicals, Inc.) was applied to the film with a thickness of 0.8 μm using the microgravure coating method, the liquid crystal was aligned with hot air for 1 minute, and in a nitrogen gas atmosphere It hardened | cured with the illumination intensity of 0.5 mJ / cm < ² >, and obtained the base material.

The substrate was coated with UV flexo cold foil adhesive KR-8, which is an ultraviolet curable adhesive, on the entire surface with a flexographic printing machine to a thickness of 5 μm, and a transfer foil was laminated together, and cured with a light amount of 200 mJ / cm ² . The transfer substrate was peeled off to obtain a laminate.

  An acrylic adhesive layer was applied to the back surface of the obtained laminate with a thickness of 15 μm, and a separator was attached to obtain a sticker shown in FIG.

  The sticker thus obtained was of a good quality without damage caused by heat or pressure. Moreover, although it looks like a hologram sticker, a latent image with a high contrast appeared when a polarizing film was overlaid, and it was possible to determine authenticity.

It is sectional drawing which shows the base material and transfer foil at the time of providing a phase difference layer in the base material side. It is sectional drawing which shows the base material and transfer foil at the time of providing a phase difference layer in the transfer foil side. It is the schematic of the transfer processing machine used for this invention. It is sectional drawing of the sticker using the laminated body of this invention.

Explanation of symbols

11, 41 Base material 12, 24, 43 Phase difference layer 2 Transfer foil 21 Transfer base material 22, 46 Release layer 23, 44 Reflective layer 31 Substrate unwinding 32 Base material winding 33 Adhesive layer coating 34 Transfer foil unwinding 35 Transfer foil winding 36 UV lamp 42 Adhesive layer 45 Diffraction structure forming layer 47 Adhesive layer 48 Separator

Claims (11)

A substrate;
A retardation layer having a slow axis in the planar direction of the substrate;
An adhesive layer made of ultraviolet or electron beam curable resin;
A laminated body comprising a transfer foil including a reflective layer and a release layer laminated in this order. A substrate;
An adhesive layer made of ultraviolet or electron beam curable resin;
A laminate comprising a retardation layer having a slow axis in the planar direction of the substrate, a transfer foil including a reflective layer and a release layer, which are laminated in this order.   The laminate according to claim 1 or 2, wherein the substrate does not have optical anisotropy.   The laminate according to claim 1 or 2, wherein the base material is a base material in which a slow axis direction and a retardation value are controlled.   The laminate according to claim 1, wherein the reflective layer has a diffractive structure.   The laminate according to any one of claims 1 to 5, wherein the transfer foil has the release layer as an outermost layer, and an adhesive layer is further laminated on the release layer side.   A paper in which the laminate according to any one of claims 1 to 6 is rolled into a paper material. Forming a retardation layer having a slow axis in the planar direction of the substrate on the substrate;
Applying an adhesive layer made of an ultraviolet ray or an electron beam curable resin to either one of the base material and the phase difference layer;
Bonding the transfer foil containing the reflective layer, the release layer and the transfer substrate to the surface to which the adhesive layer is applied; and
Curing the adhesive layer using ultraviolet light or electron beam;
And a step of peeling off the transfer substrate. Forming a retardation layer having a slow axis in the planar direction of the substrate on the substrate;
Applying an adhesive layer made of ultraviolet or electron beam curable resin to the transfer surface of the transfer foil including the reflective layer, the release layer, and the transfer substrate;
Bonding the transfer foil to one surface of the substrate on which the retardation layer is formed via the adhesive layer;
Curing the adhesive layer using ultraviolet light or electron beam;
And a step of peeling off the transfer substrate. On the transfer substrate, creating a transfer foil comprising at least a release layer, a reflective layer, and a retardation layer having a slow axis in the planar direction of the transfer substrate;
Applying an adhesive layer made of ultraviolet or electron beam curable resin on the substrate;
Bonding the transfer foil to the surface of the substrate on which the adhesive layer is applied;
Curing the adhesive layer using ultraviolet light or electron beam;
And a step of peeling off the transfer substrate. On the transfer substrate, creating a transfer foil comprising at least a release layer, a reflective layer, and a retardation layer having a slow axis in the planar direction of the transfer substrate;
Applying an adhesive layer made of ultraviolet or electron beam curable resin to the transfer surface of the transfer foil;
Bonding the substrate to the surface to which the adhesive layer has been applied;
Curing the adhesive layer using ultraviolet light or electron beam;
And a step of peeling the transfer substrate.