JP5233264B2 - Transcript - Google Patents

Description

  The present invention relates to a transfer foil that uses an article for discrimination between a genuine product and a non-genuine product, a transfer method thereof, and a transfer product.

  It is desired that counterfeiting is difficult for authentication media such as cash cards, credit cards and passports, and securities media such as gift certificates and stock certificates. Therefore, conventionally, a label that is difficult to forge is attached to such a medium in order to prevent the forgery.

  In recent years, the distribution of counterfeit products has been regarded as a problem for articles other than authentication media and securities media. Therefore, the opportunity to apply the above-described anti-counterfeiting technology for authentication media and securities media to such articles is increasing.

  The forgery prevention technology can be classified into an overt technology and a covert technology. The overt technique is an anti-counterfeiting technique that allows a general user to easily recognize application to an article and easily determine whether it is authentic. A typical overt technique utilizes a diffraction structure such as a hologram or a multilayer interference film such as Optically Variable Ink (OVI).

  The covert technique is an anti-counterfeiting technique aimed at making it possible for only a specific user who knows the application of the covert technique to an article to make a true / false judgment because it is difficult for general users to understand the application to the article. Typical covert techniques use fluorescent printing or line moire.

  Patent Document 1 describes another covert technique. In this covert technique, a technique for introducing a latent image by combining a reflective layer, a photo-alignment film, and a photo-curable liquid crystal layer is introduced.

  When this technique is used as a transfer foil, a release protective layer, a molecular orientation layer, and an adhesive layer are formed on a substrate in this order. In the security printing field, the transfer foil is transferred as a thin film to the transfer target, and therefore, when it is re-peeled, it is broken and cannot be replaced. Therefore, it is generally considered that the security is high, and it is frequently used.

  The transfer foil is generally hot stamped in a spot shape in addition to the roll transfer in a stripe shape. In the case of transfer with a spot, the peeling from the peeling protective layer to the adhesive layer breaks in the contour shape of the stamper at the time of peeling, but at the beginning of peeling, peeling resistance and breaking resistance are applied at the same time, and the adhesive layer does not reach the adhesive force and transfer. May cause chipping. At the end of peeling, burrs may occur if the breaking resistance exceeds the peeling resistance. In addition, if a large resistance is applied at the time of peeling in the transfer machine, the material to be transferred may be broken, the foil may meander or the like.

  In particular, when an alignment resin such as liquid crystal is used, anisotropy is generated in the fracture resistance, so attention must be paid to the alignment direction.

The known literature is described below.
JP-A-8-43804

  The present invention has been made to solve the above-mentioned problems, and in a transfer foil containing a material exhibiting fracture resistance anisotropy caused by molecular orientation, delamination by devising the molecular orientation direction. It is an object of the present invention to provide a transfer foil, a transfer method thereof, and a transfer product in which resistance is sometimes dispersed, transfer defects and burrs are reduced, and workability is stable.

As a means for solving the above problems, first, the invention according to claim 1 is formed by sequentially laminating at least a molecular orientation layer and an adhesive layer on a base material, and the molecular orientation layer and the adhesive layer are peeled from the base material. The transfer is possible by forming a diffractive structure forming layer between the molecular orientation layer and the adhesive layer, and forming an entire surface or a patterned reflective layer between the diffractive structure forming layer and the adhesive layer. A transfer product obtained by transferring a foil, wherein the molecular alignment layer is cured.

The invention according to claim 2 is that the transfer foil is peeled off and transferred so that the molecular orientation direction of the molecular orientation layer and the peeling direction θ are not parallel to at least a part of the contour portion of the transfer shape. The transfer product according to claim 1.

  According to the present invention, by controlling the orientation direction of the molecular orientation layer that causes anisotropy in breaking resistance, the resistance applied at the time of peeling is dispersed, transfer defects and burrs are reduced, and the transfer foil has stable workability, It becomes possible to provide a transfer method and a transcript.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating transfer of the transfer foil of the present invention. FIG. 2 is a schematic plan view for explaining the occurrence of chipping and burrs in the transfer of the transfer foil. FIG. 3 is a plan view showing an example of the transfer foil of the present invention. 4 is a cross-sectional view taken along the line III-III 'of FIG. FIG. 5 is a schematic plan view of a transfer product obtained by transferring the transfer foil of the present invention to a transfer sheet. FIG. 6 is a plan view showing a state in which a latent image is visualized by superimposing a polarizer on the transfer material of the present invention.

The transfer foil of the present invention is formed by sequentially laminating at least a molecular orientation layer and an adhesive layer on a substrate,
The molecular orientation layer and the adhesive layer are detachable from the substrate.

  As shown in FIG. 4, a transfer foil 40 as an embodiment of the present invention is formed by sequentially laminating at least a molecular (liquid crystal) alignment layer 43 and an adhesive layer 47 on a base material 41, and further, the molecules A diffractive structure forming layer 44 may be formed between the alignment layer 43 and the adhesive layer 47, and an entire or patterned reflective layer 45 may be formed between the diffractive structure forming layer 44 and the adhesive layer 47. Here, in the present invention, it is preferable to provide the peeling protective layer 42.

  As the base material 41 in the present invention, a film made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polyethersulfone (PES), polyimide, or the like can be used. In order to adjust the peeling resistance, a release layer remaining on the substrate side after transfer may be provided. The material used for the release layer is generally a thermosetting resin using melamine or isocyanate as a curing agent, or a UV / EB curable resin using acrylate or epoxy resin, and fluorine or silicon as a release agent. System monomers and polymers are added.

  The peeling protective layer 42 in the present invention is stably peeled off from the base material or the release layer and becomes a layer located on the outermost surface after transfer, and therefore requires surface protection performance according to the purpose of use. As the material used for the release layer, curable resins such as UV curable acrylic and baking melamine resin can be used in addition to thermoplastic resins such as acrylic, styrene, nitrified cotton, and cellulose acetate. A resin satisfying these performances is provided on the substrate using a gravure coater, a micro gravure coater, a roll coater or the like. Since the wear resistance is improved by adding a lubricant such as polyethylene wax or zinc stearate to the resin, it may be added.

  The molecular alignment layer 43 in the present invention is a birefringent layer in which the entire surface is aligned in one direction or in two or more directions for each region. When viewed without passing through a polarizer, it appears only as a transparent layer. It is a layer that causes a latent image to appear when observed through a polarizer.

  As a material for forming the molecular alignment layer, a photocurable liquid crystal monomer having acrylates at both ends of a mesogenic group is applied. A polymer liquid crystal cured by electron beam (EB) or ultraviolet light (UV), a polymer liquid crystal in which a mesogenic group is provided in the polymer main chain, or a liquid crystal polymer in which the molecular main chain itself is aligned can be used. These liquid crystals can be heat-treated at a temperature slightly below the NI point after coating to promote alignment.

  As a method for aligning the liquid crystal in one direction, a method for aligning the molecular alignment of the stretched film, a photo alignment method, a rubbing alignment method, or the like can be used.

  The photo alignment method is a method of inducing rearrangement of molecules in the film and anisotropic chemical reaction by irradiating the film on the substrate with anisotropic light such as polarized light or non-polarized light from an oblique direction. Thus, anisotropy is imparted to the film, thereby utilizing the orientation 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.

  The rubbing 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. It is a thing. For the alignment film, polyimide, polyvinyl alcohol (PVA), or the like is used.

A molecular alignment layer in which liquid crystal is aligned in two or more directions for each region can be produced by coating liquid crystal on an alignment film formed so that the liquid crystal is aligned in two directions. In order to form the alignment film so that the liquid crystal is aligned in two directions, a photo alignment method or a rubbing alignment method can be used.

  When using the photo-alignment method, pattern exposure through a photomask with polarized light in an appropriate wavelength band or non-polarized light from an oblique direction, and exposure by changing the direction to process the unexposed area An alignment film that aligns the liquid crystal in the direction can be formed.

  Also, the entire surface of the alignment agent applied on the substrate is rubbed with a cloth, partially masked, and the direction is changed again and rubbed with the cloth, and then the mask is removed to align the liquid crystal in two directions. An alignment film can be formed.

  As a method for forming these alignment films, a known method such as a gravure coating method or a micro gravure coating method can be used.

  As the molecular alignment layer aligned in one or two directions, an alignment film itself having an alignment property can be used by a photo-alignment method or a rubbing method, and a manufacturing method is not limited. Further, when peeling from the alignment film or the molecular alignment layer, the peeling protective layer is omitted.

  The birefringent material is a material having a transparent birefringence. Birefringence means that the refractive index of a substance varies depending on the optical axis direction. When light is incident on a substance having birefringence, extraordinary ray e (refractive index: ne) and ordinary ray o (refractive index: no). Is a phenomenon that causes a phase difference between the two. These optical axis differences cannot be discerned visually without passing through a polarizing film.

  This difference in refractive index between extraordinary rays and ordinary rays is called birefringence Δn and is expressed by the following equation.

Δn = ne-no
Further, the phase difference value δ is proportional to the layer thickness d passing through the birefringent material and is expressed by the following equation.

δ = Δn · d
That is, the phase difference value is proportional to the film thickness. Further, when a reflective layer is used, the phase difference value is doubled because the birefringent material passes twice before and after reflection.

  When the phase difference value is half the wavelength λ of transmitted light (λ / 2), when the angle between the extraordinary optical axis of the birefringent material and the polarization plane of the polarized light is θ, the polarization plane has the property of rotating 2θ. Therefore, when θ = 45 °, the polarization plane rotates 90 °.

  When a retardation film having a retardation value of λ / 4 is formed on the reflective layer and a polarizing film is overlaid, when the angle formed between the transmission optical axis of the polarizing film and the abnormal optical axis of the retardation film is 45 ° When the light transmitted through the polarizing film rotates by 90 ° and returns to the polarizing film, it cannot be transmitted, and thus becomes a dark part. In addition, when the angle formed by the transmission optical axis of the polarizing film and the abnormal optical axis of the phase retarder is 0 °, the light transmitted through the polarizing film returns as it is, so that the polarizing film can be transmitted, so that a bright portion is obtained. . That is, a latent image appears when passing through a polarizing film.

  When the diffractive structure forming layer 44 is provided, it may be provided either above or below the molecular alignment layer. The diffractive structure forming layer is a material that is easy to mold when a heated diffractive structure plate is pressed, and is further provided with a material that does not easily collapse the diffractive structure due to heat during processing of the reflective layer and heat pressure during transfer.

As the diffractive structure, a hologram and a diffraction grating can be used. The hologram is a relief type master plate made of a fine uneven pattern by an optical photographing method, and then a nickel press plate is produced by duplicating the uneven pattern from the master plate by an electroplating method, and Mass replication is performed by a method in which the press plate is heated and pressed onto a layer on which a hologram is formed.

  This type of hologram is called a relief hologram. In contrast to holograms that capture such actual objects, diffraction gratings are used by arranging multiple types of simple diffraction gratings in a small area as pixels, grating images, dot matrices (pixelgrams). Or the like). An image using such a diffraction grating is mass-replicated in the same manner as a relief hologram.

  A reflective layer may be provided on the transfer foil of the present invention. The reflection layer may also serve as a reflection layer for the latent image and a reflection layer for the diffraction structure image. Moreover, you may provide separately.

The reflective layer 45 in the present invention 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 TiO 2, ZnS, a high refractive index material such as Fe ₂ O ₃ is used. These materials are coated with a thickness of about 10 nm to 100 nm using vapor deposition, sputtering, ion plating, or the like. In the processing for forming these reflective layers, a thermal load is applied to the processed surface. Therefore, since the surface to be processed is required to have heat resistance, when an inappropriate material is on the outermost surface, the surface is modified using a wet coating such as microgravure or direct gravure method, It is desirable to provide a reflective layer.

  When the reflective layer is provided in a pattern, that is, in order to form a pattern by a portion (12) having no reflective layer and a portion (13) having a reflective layer, it is possible to use washing sea light processing, etching processing, laser processing, or the like. it can.

  Washed sea light processing is a pre-printed negative ink pattern on the base material, forming a reflective layer on the entire surface, washing the washed ink with water and removing the reflective layer to remove the patterned metal thin film. It is a method of forming.

  Etching is a method of forming a patterned metal thin film by forming a reflective layer, printing a masking agent in a positive pattern, and removing the unmasked portion by corroding with a corrosive liquid. . This etching method cannot be used when there is no appropriate corrosive solution for corroding the reflective layer.

Laser processing is a method of forming a patterned metal thin film by forming a reflective layer on a substrate and partially removing it by applying a strong laser. As a laser to be used, a Nd: YAG, CO ₂ gas laser is generally used.

  The transfer foil of the present invention can be provided with a polarizing layer between any of the layers. The polarizing layer described here is a layer having the ability to separate a specific polarization component from natural light, absorbs light in the absorption axis direction in which the dichroic dye is oriented, and transmits light in the transmission axis direction. A layer that separates polarized light, a layer that separates polarized light by aligning cholesteric liquid crystal, reflecting circularly polarized light on one side, and transmitting the other.

  The adhesive layer 47 in the present invention uses a heat-sensitive adhesive that exhibits tackiness when heated. For the adhesive layer, a resin satisfying these performances is provided on the substrate using a gravure coater, a micro gravure coater, a roll coater or the like. As a material that can be used, thermoplastic resins such as acrylic, vinyl chloride vinyl acetate copolymer, epoxy, and EVA can be used. In addition, when the ceramic reflective layer or the patterned reflective layer is used by coloring the adhesive layer, the visibility of the pattern by the latent image and the image by the diffraction structure may be improved.

  Next, the transfer method for the transfer foil of the present invention will be described. As a transfer method, the transfer foil is transferred onto a transfer sheet by spot transfer using an up-down method or stripe transfer using a roll transfer method. The transfer paper is not particularly limited as long as it is a sheet, such as a resin film, a metal plate, or a glass plate, in addition to paper. In addition, when a reflective layer or a polarizing layer is not provided on the transfer foil, a reflective layer or a polarizing layer can be provided on the transfer paper side.

  In order to transfer the transfer foil of the present invention, an up-down type transfer machine is used. As shown in FIG. 1, the up-down type transfer machine has a hot stamp (11) in which a transfer foil (13) is superimposed on the transfer sheet (14) placed on a pedestal (12) from the adhesive layer side and heated. The adhesive layer is softened in the shape of a hot stamp by pressurizing with, and adhered to the transfer paper (21), and then peeled off and transferred to the transfer paper.

  Peeling begins to peel from the peeling start side (24), which is the winding side of the foil. In this part, the part from the peeling layer to the adhesive layer starts from the part adhered to the transfer paper (14) by the adhesive layer. The sum of the breaking resistance RS (15) to be broken and the peeling resistance RR (16) when the peeling layer is peeled off from the substrate is simultaneously applied. If this exceeds the adhesive force FA (24), it will cause chipping. That is, if it is the following formula [1], it can be transferred without any chipping.

RS <FA-RR ･ ･ ･ [1]
In the peeling center (25), the transfer can be stably performed if the adhesive force FA exceeds the peeling resistance RR. That is, the following formula [2] may be used.

FA> RR ... [2]
Further, on the peeling end side (25), which is the unwinding side of the foil, when the breaking resistance RS (18) is larger than the peeling resistance RR (19), the foil does not break according to the transfer shape by the hot stamp, and burrs are generated. Occur. That is, if the following formula [3] is used, transfer can be performed without burrs.

RS <RR ･ ･ ･ [3]
In a material having molecular orientation, the breaking resistance RP in the orientation direction is generally larger than the breaking resistance RC perpendicular to the molecular orientation. This is because the orientation direction is strongly bonded by a covalent bond, whereas the direction perpendicular to the molecular orientation is weakly bonded by van der Waals force. That is, it is represented by the following formula [4].

RP> RC ... [4]
Therefore, the rupture resistance RS on the peeling start side (24) and the peeling end side (26) is expressed by the following formula [5], where θ is an angle formed between the peeling direction and the molecular orientation direction.

RS = RPSinθ + RCCosθ .. [5]
From these formulas [4] and [5], when θ = 90 °, chipping and burrs are unlikely to occur, resistance to peeling is small, transfer failure and tear of the transfer paper in the transfer machine are prevented, and transfer foil Improves position violence due to meandering. The closer to 0, the more likely the problem described above occurs. Therefore, θ is more preferably in the range of 45 to 90 ° other than 0 °, and more preferably 90 °.

  Similarly, when the transfer method is roll transfer, chipping and burrs can be reduced at the beginning and end of transfer of the transfer foil, respectively, and workability can be improved.

A PET film substrate (41) having a thickness of 16 μm is coated with a photo-alignment agent IA-01 (manufactured by Dainippon Ink & Chemicals, Inc.) at a thickness of 0.1 μm using a microgravure coating method and then peeled off. It formed as a protective layer and photo-alignment film (42). Using linearly polarized light having a wavelength of 365 nm, the entire surface is exposed with an illuminance of 1 J / cm 2 so that the direction of polarized light is perpendicular to and perpendicular to the peeling direction, and then the direction of polarized light is rotated by 45 ° for each photomask 1 J / cm ² pattern was exposed. A UV curable liquid crystal UCL-008 (manufactured by Dainippon Ink & Chemicals, Inc.) was applied to this film with a thickness of 0.8 μm using a micro gravure coating method, and the liquid crystal was aligned with hot air for 1 minute, and in a nitrogen gas atmosphere Was cured at an illuminance of 0.5 mJ to obtain a liquid crystal alignment layer (43).

  Further, a diffraction structure forming layer (44) composed of acrylic polyol and isocyanate is applied by a microgravure coating method, and heated to emboss with a plate having a diffraction structure to form a diffraction structure image (33). Vapor deposition was performed with a thickness of 50 nm, and a mask layer (46) made of a vinyl chloride vinyl acetate copolymer was provided with a thickness of 1 μm by gravure printing.

  Subsequently, etching was performed in a caustic soda aqueous solution at 50 ° C. for 1.5 seconds to form a reflective layer (32, 45) of a pattern, and an adhesive layer (47) made of a vinyl chloride vinyl acetate copolymer was formed. Coating was performed with a thickness of 2 μm to obtain transfer foils (30, 40).

  The transfer portion (51) was transferred to the transfer paper obtained using a transfer stamp (manufactured by Gietz) using a transfer shape (31) hot stamp to obtain a transfer product (50). The transfer foil oriented perpendicular to the peeling direction could be transferred without chipping or burrs. In the transfer foil oriented parallel to the peeling direction, burrs occurred. Also, the peeling was heavy, the foil meandered, and the transfer position was out of order. When the polarizer (63) was placed on the transfer portion of the transferred material, latent images according to the orientation of the liquid crystal appeared, and when the polarizer was rotated, the positive and negative of the latent image were reversed every 45 °.

It is a schematic sectional drawing explaining transfer of the transfer foil of this invention. It is an outline top view explaining generating of a chip and a burr in transfer of a transfer foil. It is a top view which shows an example of the transfer foil of this invention. It is sectional drawing of the transfer foil of this invention in III-III 'of FIG. FIG. 3 is a schematic plan view of a transfer product obtained by transferring the transfer foil of the present invention to a transfer paper. It is a top view which shows the state in which the latent image was visualized by making a polarizer overlap with the transcription | transfer material of this invention.

Explanation of symbols

11 Hot stamp 12 Pedestal 13, 22, 30 Transfer foil 14, 21 Transfer paper 15, 18 Shear resistance 16, 19 Peel resistance 17 Adhesive force 23, 31 Transfer shape 24 Peel start side 25 Peel center 26 Peel end side 32, 45 Reflective layer 33 Diffraction structure image 34 Polarized latent image 41 Base material 42 Peeling protective layer (photo-alignment film)
43 Liquid crystal alignment layer 44 Diffraction structure forming layer 46 Mask layer 47 Adhesive layer 50, 60 Transfer product 51 Transfer part 52, 62 Transfer sheet 61 Latent image 63 Polarizer RP Breaking resistance RC of liquid crystal alignment direction RC Liquid crystal alignment and orthogonal direction Breaking resistance θ Angle formed by liquid crystal alignment direction and peeling direction

Claims (2)

On the substrate, at least a molecular alignment layer and an adhesive layer are sequentially laminated. The molecular alignment layer and the adhesive layer can be peeled from the substrate, and a diffractive structure is formed between the molecular alignment layer and the adhesive layer. A transfer product obtained by transferring a transfer foil formed by forming an entire surface or a patterned reflective layer between the diffraction structure forming layer and the adhesive layer, wherein the molecular orientation layer is cured. Transcript characterized by 2. The transfer according to claim 1, wherein the transfer foil is peeled off and transferred so that the molecular orientation direction of the molecular orientation layer and the peeling direction θ are not parallel to at least a part of the contour portion of the transfer shape. object.