JP2010256595A - Optical element transfer foil and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element transfer foil capable of peeling cured radiation resin occluded in a relief mold from the relief mold as being integrated with a base material and after that, a resin part is separated from the base material to be transferred on a medium to be transferred only by adhering the cured resin side to another medium to be transferred, when the optical element transfer foil is manufactured by a photopolymer method. <P>SOLUTION: In the optical element transfer foil, at least the film-like base material, a release layer formed by curing a first radiation cured resin, and a relief pattern layer formed by curing a second radiation cured resin are laminated in this order, and wavelength of radiation which hardens the first radiation cured resin is shorter than wavelength of radiation which hardens the second radiation cured layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical element transfer foil having a fine relief pattern and a method for producing the same.

  The present invention relates to an optical element transfer foil having a fine relief pattern and a method for producing the same. Examples of optical elements that can be used as optical element transfer foils include Fresnel lens plates and lenticular plates used in relief holograms, diffraction gratings, sub-wavelength gratings, microlenses, polarizing elements, screens, and backlights for liquid crystal display devices. Diffusing plate, antireflection film and the like.

  By making these optical elements into a transfer foil form, they can be attached to various articles with high productivity in the manner of hot stamping, etc., and are used as anti-counterfeiting optical members such as banknotes and ID cards. .

  In recent years, optical elements having a finer and higher aspect ratio have been used. For example, as a fine structure having a wavelength equal to or less than the wavelength of light, a sub-wavelength grating manufactured using a photopolymer method, a structure having a high aspect ratio, Examples thereof include a polarization separation element and a non-reflective structure.

The photopolymer method is described in, for example, Patent Document 1, and a radiation curable resin is poured between a relief mold (a mold for replicating a fine relief pattern) and a flat substrate (plastic film, etc.). This is a method of obtaining a high-definition fine relief pattern by a method in which the cured resin film is peeled off from the relief mold together with the substrate after being cured by radiation irradiation.
The optical element obtained by this method has better forming accuracy of the concavo-convex pattern and is excellent in heat resistance and chemical resistance than the pressing method and casting method using a thermoplastic resin.

  However, in order for the fine structure formed on the flat base material to be a transfer foil that can be transferred to another transfer medium, it is necessary that the fine structure portion can be peeled from the flat base material.

  In addition, if the adhesion strength between the relief mold and the cured radiation resin is heavy, there is a problem that the relief plate is soiled by the radiation resin adhering to the relief mold during separation. Such a problem at the time of molding is likely to occur particularly in a fine structure having a high aspect ratio, and it is considered that the adhesion strength between the relief mold and the radiation curable resin is enhanced by the fine structure.

  To solve this problem, there is a method in which a release agent such as a silicone compound or a fluorine compound is blended in the radiation curable resin to lower the adhesion strength between the relief mold and the radiation curable resin. For example, Patent Literature 2, Patent Literature 3, and Patent Literature 4 disclose techniques for blending or copolymerizing a silicone compound or a fluorine compound with a radiation curable resin. However, these additives have a problem of becoming cloudy depending on the amount added.

  Hereinafter, this point will be explained. When the relief plate soiling during the molding process has a stronger “adhesion between the relief pattern layer and the relief plate” than “adhesion between the film substrate and the release layer”, the release layer And the relief pattern forming layer is peeled off from the base film and adhered to the relief plate.

For this reason, when the peel strength required for the transfer foil is very light (when the adhesion between the film substrate and the release layer is very weak), a large amount of the relief forming layer is used to prevent the stain on the relief plate. It is necessary to add or copolymerize a release agent, and as a result, the coating film becomes cloudy.
Therefore, it has been difficult to simultaneously satisfy the problem of the relief plate stain and the white turbidity of the coating film only by the method of adding or copolymerizing the release agent.

Patent No.4088884 JP 2001-310340 Patent 3355308 JP 2007-118563 A

  Therefore, in producing the optical element transfer foil by the photopolymer method, the problem of the present invention is that the cured radiation resin engaged with the relief mold can be peeled from the relief mold while being integrated with the base material, and then, It was decided to provide an optical element transfer foil that can be transferred onto a transfer medium by separating the resin portion from the substrate simply by adhering the cured resin side to another transfer medium.

  In order to achieve the above object, the first invention comprises at least a film-like substrate, a release layer obtained by curing the first radiation curable resin, and a second radiation curable resin. The relief pattern layer is an optical element transfer foil laminated in this order, and the wavelength of the radiation obtained by curing the first radiation curable resin is the wavelength of the radiation obtained by curing the second radiation curable resin. The optical element transfer foil is characterized by being shorter.

  According to a second aspect of the present invention, the first radiation curable resin has a tack property before radiation irradiation and has a property of being tack-free after radiation irradiation. This is an element transfer foil.

  The third invention is characterized in that the first radiation curable resin contains an electron beam curable resin, and the second radiation curable resin contains an ultraviolet curable resin. This is an optical element transfer foil.

  The fourth invention is the optical element transfer foil according to any one of claims 1 to 3, wherein the relief pattern in the relief pattern layer has an aspect ratio of 0.5 or more. Is.

  According to a fifth aspect of the invention, in the optical element transfer foil according to any one of claims 1 to 4, wherein the relief pattern in the relief pattern layer has a sub-wavelength structure equal to or less than the wavelength of light. It is a thing.

  The sixth invention includes a step of applying a first radiation curable resin and a second radiation curable resin to the surface of the film-shaped substrate to form a laminate, and a second radiation curing of the laminate. A step of engaging a relief mold having a relief pattern with a mold resin, a step of irradiating the second radiation curable resin of the laminate with radiation to cure only the second radiation curable resin, and a relief mold A method for producing an optical element transfer foil, comprising: a step of peeling off the laminate, and a step of irradiating the first radiation curable resin of the laminate with radiation to cure. .

According to the present invention, since the peel strength between the film-like substrate and the relief pattern layer can be set to be heavier than the peel strength between the relief pattern layer and the relief mold, the relief pattern layer can be easily peeled from the relief mold, An optical element transfer foil can be obtained without producing relief plate stains remaining in the relief mold.
Furthermore, in terms of the adhesive force with the transfer medium, the peel strength between the film-like substrate and the relief pattern layer can be made relatively lighter than the peel strength between the relief pattern layer and the transfer medium by re-irradiation with radiation. Therefore, the relief pattern layer can be easily transferred onto the transfer medium.

Sectional drawing of an optical element transfer foil. Sectional drawing of the laminated body before relief pattern transfer. Explanatory drawing of the manufacturing method of an optical element. Sectional drawing of the laminated body after relief pattern transfer. The figure at the time of transferring an optical element transfer foil to a to-be-adhered body.

  Hereinafter, an optical element transfer foil and a manufacturing method thereof according to the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an optical element transfer foil according to the present invention. This optical element transfer foil 1 has a multilayer structure of a release layer 3, a fine relief pattern layer 4, a reflective layer 5, and an adhesive layer 6 provided on a film-like substrate 2. Note that the reflective layer 4 is not necessary depending on the structure of the desired optical element. Further, when the transfer medium has an adhesive layer, the adhesive layer 6 is not always necessary.

  In addition, a protective layer for protecting one of the surface layers of the optical element, a high refractive index layer or a reflective layer for improving the efficiency of the optical effect, an anchor layer for improving interlayer adhesion, or corona treatment for each layer. It is also possible to perform plasma processing or flame processing.

  FIG. 2 is a cross-sectional view of the laminate before the relief pattern 4 is transferred to the relief pattern forming layer using a relief mold. The laminate 10 has a multilayer structure of a film-like substrate 2, a release layer 3, and a relief pattern layer 4.

FIG. 3 is a diagram schematically illustrating a method for producing an optical element transfer foil according to the present invention.
The laminate 10 before transferring the relief pattern is conveyed from the left side to the right side of the drawing and is pressed when sandwiched between the cylindrical relief pattern original plate 11 and the press roll 12, and heated if necessary. The pattern of the relief pattern original 11 fits exactly into the relief pattern forming layer. Thereafter, the relief pattern forming layer 4 is irradiated with radiation by the radiation irradiator 13, whereby only the forming layer 4 is cured. The release layer 3 is not energetically cured. Subsequently, the laminate on which the relief pattern is formed is peeled off from the relief pattern original plate to obtain an optical element transfer foil. FIG. 4 is a cross-sectional view of the laminate after the relief pattern transfer.

At this point, the release layer 3 remains uncured, but has sufficient tackiness with respect to the film substrate 2 and the relief pattern layer and remains integrated.
At this time, the adhesion strength of the release layer 3 to the film substrate 2 and the relief pattern layer is set to be heavier than the adhesion strength of the relief original plate 11 and the relief pattern layer 4 after curing, so that the release original layer 11 is closer to the relief original plate 11 at the time of peeling. Occurrence of the relief plate stain left by the relief pattern layer can be suppressed.

  Next, the release layer 3 is cured by irradiating radiation having a wavelength shorter than the first irradiation wavelength by the radiation irradiator 14. Since the tackiness of the release layer 3 is lost by re-irradiation, the adhesion between the film substrate and the relief pattern layer is lowered. As a result, if the relief pattern layer is bonded to another transfer medium, this adhesive force is superior, and the relief pattern layer can be easily peeled off from the film substrate. That is, it is possible to obtain an optical element transfer foil excellent in transferability.

  FIG. 5 is a diagram schematically illustrating a state in which the optical element transfer foil 1 of the present invention is transferred to the transfer medium 7.

  The optical element transfer foil has a multilayer structure of a release layer 3, a relief pattern layer 4, a reflective layer 5, and an adhesive layer 6 provided on a film-like substrate 2.

  By providing the reflective layer 5 on the relief-shaped surface, it is possible to emphasize the optical effect due to the relief shape and observe the optical effect by reflection. The reflective layer is not indispensable, and may be appropriately installed according to the required optical effect and layer structure. For such a reflective layer, a single metal material such as Al, Sn, Cr, Ni, Cu, Au, or Ag, or a compound thereof, ceramics, an organic polymer, or the like can be used as a transparent reflective layer.

  These materials may be formed by known vacuum deposition or sputtering. Alternatively, high-brightness ink obtained by kneading fine powders of these materials into a binder resin may be provided by wet coating.

  Further, the reflective layer may be partially provided. As a method for providing such a partial reflective layer, for example, an “etching method” in which a reflective layer is provided on the entire surface by a vacuum deposition method, a pattern mask is printed, and a reflective layer in a portion without a mask is etched, There is a “water-washing pasta method” in which a “washing ink” that can be washed in advance is printed in a pattern, and then a reflective layer is provided by a vacuum deposition method, and then the reflective layer on the washing ink is removed by washing with water.

  The adhesive layer 6 is a known heat-sensitive resin (heat-sensitive adhesive material) having a function of adhering to the transfer material by being applied with heat and pressure in contact with various transfer materials (for example, paper / plastic). Is used. Further, an adhesive using an ultraviolet curable resin or an electron beam curable resin may be used. If the adhesive is made of such a material, it can be adhered to the transfer object by a cold transfer method.

  In this figure, the release layer 3 is separated from the fine relief pattern layer, and the relief pattern layer is transferred onto the transfer medium. You may make it peel between layers with the layer 3. FIG. The adhesion strength between the film-like substrate 2 and the release layer 3 and the adhesion strength between the release layer 3 and the relief pattern layer may be adjusted. For example, in addition to adjustment by surface roughness, adjustment by corona treatment, plasma treatment, and frame treatment Alternatively, the interlayer adhesion strength may be adjusted by anchor coating.

  As described above, according to the present invention, when the optical element transfer foil is manufactured, the peeling strength of the transfer foil from the relief mold is heavy, so that the relief plate is hardly soiled. On the other hand, the peel strength as the optical element transfer foil is reduced. Is possible.

  Below, each layer concerning this invention is demonstrated in detail.

(Relief pattern forming layer)
The relief pattern forming layer is made of a resin that is cured by radiation.
As an example of the radiation curable resin, a monomer, oligomer, polymer or the like having an ethylenically unsaturated bond can be used. Examples of the monomer include 1,6-hexanediol, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and the like. . Examples of the oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate. Examples of the polymer include urethane-modified acrylic resins and epoxy-modified acrylic resins.

  Examples of other photocurable resins are described in JP-A-61-98751, JP-A-63-23909, JP-A-63-23910, and JP-A-2007-118563. The photocurable resin which can be mentioned is mentioned. In addition, in order to accurately form a fine relief pattern, a polymer such as an acrylic resin, a polyester resin, a urethane resin, or an epoxy resin having no reactivity can be added.

  Moreover, when utilizing photocationic polymerization, an epoxy group-containing monomer, oligomer, polymer, oxetane skeleton-containing compound, and vinyl ethers can be used. Further, when the ionizing radiation curable resin is cured by light such as ultraviolet rays, a photopolymerization initiator can be added. Depending on the resin, a radical photopolymerization initiator, a cationic photopolymerization initiator, or a combination thereof (hybrid type) can be selected.

  Examples of the photo radical polymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether, and benzoin ethyl ether, anthraquinone compounds such as anthraquinone and methylanthraquinone, acetophenone, diethoxyacetophenone, benzophenone, hydroxyacetophenone, and 1-hydroxycyclohexyl. Examples include phenyl ketone compounds such as phenyl ketone, α-aminoacetophenone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, benzyldimethyl ketal, thioxanthone, acylphosphine oxide, Michler's ketone, and the like. be able to.

  As a photocationic polymerization initiator when using a compound capable of photocationic polymerization, aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, aromatic phosphonium salts, mixed ligand metal salts, etc. should be used. Can do. In the case of so-called hybrid type materials that use both radical photopolymerization and cationic photopolymerization, each polymerization initiator can be mixed and used, and a fragrance that has the function of initiating polymerization of both with a single initiator. Group iodonium salts, aromatic sulfonium salts, and the like can be used.

  The fine relief pattern forming layer according to the present invention is obtained by blending 0.1 to 15% by mass of a radiation curable resin and a photopolymerization initiator. A sensitizing dye may be used in combination with the photopolymerization initiator in the resin composition. If necessary, dyes, pigments, various additives (polymerization inhibitors, leveling agents, antifoaming agents, sagging inhibitors, adhesion improvers, coating surface modifiers, plasticizers, nitrogen-containing compounds, etc.), crosslinking An agent (such as an epoxy resin) may be included, and a non-reactive resin may be added to improve moldability. If the coating film is not cloudy, a fluorine compound or a silicone compound may be added or copolymerized in advance to improve releasability with respect to the relief original plate. May be added.

  The thickness of the fine relief pattern forming layer may be appropriately provided in the range of 0.1 to 10 μm. Although it depends on the viscosity (fluidity) of the uncured coating film, if the coating film is too thick, it may cause the resin of the uncured coating film to protrude or wrinkle during press processing, and is sufficient when the thickness is extremely thin. Can not be molded.

Moreover, since the moldability changes depending on the shape of the fine relief pattern of the original plate, it is preferable to provide a fine relief pattern forming layer having a film thickness of 3 to 10 times the desired depth.
When the fine relief pattern forming layer is provided, a coating method may be used. In particular, wet coating can be applied at a low cost. Moreover, in order to adjust a coating film thickness, you may apply | coat and dry what was diluted with the solvent. In this case, since it is provided on the uncured release layer, it is necessary to select a dilution solvent that does not re-dissolve the release layer as much as possible.
When laminating a fine relief pattern forming layer other than coating, prepare an uncured release layer coated on the film-like substrate and a fine relief pattern forming layer separately provided for transfer on the film-like substrate Then, they may be laminated and laminated.

(Release layer)
The release layer according to the present invention is characterized by containing a radiation curable resin, and is an adhesive-like property having tackiness in the state of an uncured coating that has not been irradiated with radiation, and is cured by irradiation with radiation. By doing so, it becomes tack-free, and the adhesive strength with the film substrate or the fine relief pattern forming layer is reduced, and the optical element transfer foil having a low peel strength during transfer and excellent transferability can be obtained.

The material used for the release layer is the same as that of the relief pattern forming layer, but preferably contains a radiation curable pressure-sensitive adhesive that changes the tackiness and holding power of the resin surface before and after irradiation.
In general, the adhesive strength of acrylic adhesives is controlled by tackifiers and blends with different polymers, molecular weight and distribution, copolymerization with polar monomers, crosslinking systems, etc. In such a case, the tackiness and holding force may be controlled by the same mechanism. Moreover, since it is necessary not to harden | cure with the radiation irradiated when hardening a relief pattern formation layer, it is necessary to set it as an appropriate material structure.

(radiation)
The radiation curable resin used for the relief pattern forming layer and the release layer is cured by irradiation with radiation. As the radiation, ultraviolet (UV), visible light, gamma ray, X-ray, electron beam (EB), or the like can be applied. The radiation curable resin cured by radiation may be added with a photopolymerization initiator and / or a photopolymerization accelerator in the case of ultraviolet curing, and may not be added in the case of electron beam curing with high energy. Further, by using radiation and heat in combination, the reactivity is improved, and a coating film having a high crosslinking density can be obtained.
In the present invention, when the relief pattern forming layer is cured, the release layer is not cured. Therefore, the radiation wavelength necessary to cure the release layer is used to cure the relief pattern forming layer. Shorter than the required radiation wavelength and requires higher energy. In the case of an ultraviolet curable resin, a photopolymerization initiator may be appropriately selected in consideration of a necessary radiation wavelength.

(Film substrate)
As the support substrate for providing the release layer and the relief pattern forming layer, a film-like substrate is preferable. For example, plastic films such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and PP (polypropylene) can be used, but those having heat resistance that is not deformed or deteriorated by the amount of heat applied during press molding. desirable. Moreover, when irradiating a radiation through a film-form base material, it is preferable that it is a material which cannot absorb the object radiation easily.

(Fine relief pattern)
The relief pattern of the present invention is a relief pattern having a function as an optical element, and examples thereof include a diffraction grating, a hologram, a lens, a lens array, a scattering structure, and a subwavelength structure. The sub-wavelength structure is a periodic diffractive structure having a wavelength equal to or less than the wavelength of light. For example, it is possible to obtain enhanced first-order diffracted light or zero-order diffracted light or first-order diffracted light having polarization characteristics. In recent years, research on industrial use of the special optical effect has been advanced.

The desired fine relief pattern is a “high aspect structure” in which the aspect ratio (depth / width ratio of the concavo-convex structure) is 0.5 or more, or the aspect ratio is less than 0.5. However, in the case of the “sub-wavelength structure” which is a very fine diffractive periodic structure having a wavelength equal to or smaller than the wavelength of light, the stain on the relief plate during molding is likely to occur.
This is due to the large specific surface area of the “relief plate” having the “high aspect structure” and “subwavelength structure”, and the “anchor effect (wedge) between the“ relief plate ”and the“ relief pattern layer ”. This is because the effect) ”occurs and the adhesion strength increases.
For this reason, the “adhesion between the relief pattern layer and the relief plate” is stronger than the “adhesion between the film substrate and the release layer”, and the stain on the relief plate is likely to occur.

  However, with the configuration of the present invention, the desired fine relief pattern is a “high aspect structure” or “subwavelength structure” in which the aspect ratio (depth / width ratio of the concavo-convex structure) is 0.5 or more. Even in some cases, the “adhesion between the film substrate and the release layer” can be made stronger than the “adhesion between the relief pattern layer and the relief plate” at the time of molding. It is possible to prevent.

  In the optical element of the present invention, a protective film can be provided on the outermost surface to prevent scratches, and a reflective film can be provided on the outermost surface to improve optical characteristics. A known coating method can be used for the protective film and the reflective film.

  In order to produce the anti-counterfeit laminate according to the present invention, an ink composition for a fine relief pattern forming layer and an ink composition for a release layer were prepared as shown below.

Release layer ink composition (electron beam curable resin)
Urethane (meth) acrylate pressure-sensitive adhesive (multifunctional, molecular weight 15,000) 50.0 parts by weight silica (hydrophobic silica, average particle size 3 microns) 10.0 parts by weight ethyl acetate 30.0 parts by weight Fine relief pattern forming layer ink Composition (UV curable resin)
Urethane (meth) acrylate (polyfunctional, molecular weight 20,000) 50.0 parts by weight Methyl ethyl ketone 30.0 parts by weight Ethyl acetate 20.0 parts by weight Photoinitiator (Irgacure 184 manufactured by Ciba Specialty) 1.5 parts by weight

  On the support made of a transparent polyethylene terephthalate (PET) film having a thickness of 23 μm, the release layer ink composition was applied so as to have a dry film thickness of 1 μm, and dried at 120 ° C. for 30 seconds to form a fine relief pattern forming layer. Was formed. The obtained coating film was slightly tacky, transparent and smooth.

Thereafter, the fine relief pattern forming layer ink composition is overcoated on the release coating (non-irradiated) of the release layer so as to have a dry film thickness of 1 μm, and dried at 120 ° C. for 30 seconds to form a fine relief. A pattern forming layer was formed. The obtained coating film had almost no tackiness and was transparent and smooth.

  The obtained laminate was molded by a roll photopolymer method as shown in FIG. For the original plate used for press molding, a cylindrical metal plate having a diffraction grating structure with a period of 700 nm and a depth of 200 nm is used, the press pressure is 2 kgf / cm 2, the roll temperature is 80 ° C., the press speed is 10 m / min. Molded. Simultaneously with molding, exposure was performed at 300 mJ / cm 2 with a high-pressure mercury lamp, and the shape was transferred and cured at the same time.

Stable processing was possible without forming a relief plate during molding.
The obtained forgery prevention display body had a depth shape transfer rate of 90% or more, and diffracted light from the diffractive structure could be confirmed. Even if the transfer foil in this state was peeled off by applying a paper tape to the relief surface, the optical element was not peeled off due to the strong peel strength of the transfer foil.

  Thereafter, the release layer was cured by irradiation with an electron beam. Even when a paper tape was applied to the relief surface of the obtained optical element transfer foil and peeled off, the optical element was not peeled off due to the strong peel strength of the transfer foil.

In order to produce the anti-counterfeit laminate according to the present invention, an ink composition for a fine relief pattern forming layer and an ink composition for a release layer were prepared as shown below.

Release layer ink composition (electron beam curable resin)
Urethane (meth) acrylate pressure-sensitive adhesive (multifunctional, molecular weight 15,000) 50.0 parts by weight silica (hydrophobic silica, average particle size 3 microns) 10.0 parts by weight ethyl acetate 30.0 parts by weight Fine relief pattern forming layer ink Composition (UV curable resin)
Urethane (meth) acrylate (polyfunctional, molecular weight 20,000) 50.0 parts by weight Methyl ethyl ketone 30.0 parts by weight Ethyl acetate 20.0 parts by weight Photoinitiator (Irgacure 184 manufactured by Ciba Specialty) 1.5 parts by weight

  A release layer ink composition is applied on a support made of a transparent polyethylene terephthalate (PET) film having a thickness of 23 μm so as to have a dry film thickness of 1 μm, and dried under conditions of 120 ° C. and 30 seconds to form a fine relief pattern. Layers were formed. The obtained coating film was slightly tacky, transparent and smooth.

  Thereafter, the fine relief pattern forming layer ink composition is overcoated on the release coating (non-irradiated) of the release layer so as to have a dry film thickness of 1 μm, and dried at 120 ° C. for 30 seconds to form a fine relief. A pattern forming layer was formed. The obtained coating film had almost no tackiness and was transparent and smooth.

The obtained laminate was molded by a roll photopolymer method as shown in FIG. For the original plate used for press molding, a cylindrical metal plate having a diffraction grating structure with a period of 300 nm and a depth of 300 nm is used, the press pressure is 2 kgf / cm2, the roll temperature is 80 ° C., the press speed is 10 m / min. Molded. Simultaneously with molding, exposure was performed at 300 mJ / cm 2 with a high-pressure mercury lamp, and the shape was transferred and cured at the same time.
Stable processing was possible without forming a relief plate during molding.

The obtained forgery prevention display body had a depth shape transfer rate of 90% or more, and diffracted light from the diffraction grating could be confirmed. Even if the transfer foil in this state was peeled off by applying a paper tape to the relief surface, the optical element was not peeled off due to the strong peel strength of the transfer foil.

  Thereafter, the release layer was cured by irradiation with an electron beam. Even when a paper tape was applied to the relief surface of the obtained optical element transfer foil and peeled off, the optical element was not peeled off due to the strong peel strength of the transfer foil.

  Thereafter, 0.08 micron of aluminum was vapor-deposited on the diffractive structure surface by vacuum vapor deposition, and a heat-sensitive adhesive made of acrylic resin was applied to the vapor-deposited surface to obtain an optical element transfer foil.

  The optical element transfer foil finally obtained was transferred to paper by hot stamping to obtain an optical element transfer product.

(Comparative Example 1)
In order to compare with the anti-counterfeit laminate according to the present invention, an ink composition of a fine relief pattern forming layer and an ink composition of a release layer were prepared as shown below.

Release layer ink composition (UV curable resin)
Urethane (meth) acrylate pressure-sensitive adhesive (multifunctional, molecular weight 15,000) 50.0 parts by weight silica (hydrophobic silica, average particle size 3 microns) 10.0 parts by weight ethyl acetate 30.0 parts by weight Photoinitiator (Ciba Specialty) Tea Irgacure 184) 1.5 parts by weight Fine relief pattern forming layer ink composition (UV curable resin)
Urethane (meth) acrylate (polyfunctional, molecular weight 20,000) 50.0 parts by weight Methyl ethyl ketone 30.0 parts by weight Ethyl acetate 20.0 parts by weight Photoinitiator (Irgacure 184 manufactured by Ciba Specialty) 1.5 parts by weight

  A release layer ink composition is applied on a support made of a transparent polyethylene terephthalate (PET) film having a thickness of 23 μm so as to have a dry film thickness of 1 μm, and dried under conditions of 120 ° C. and 30 seconds to form a fine relief pattern. Layers were formed. The obtained coating film was slightly tacky, transparent and smooth.

  Thereafter, the fine relief pattern forming layer ink composition is overcoated on the dry coating film of the release layer (unirradiated) so as to have a dry film thickness of 1 μm, and dried under the conditions of 120 ° C. and 30 sec to form a fine relief pattern. A forming layer was formed. The obtained coating film had almost no tackiness and was transparent and smooth.

  The obtained laminate was molded by a roll photopolymer method as shown in FIG. For the original plate used for press molding, a cylindrical metal plate having a diffraction grating structure with a period of 700 nm and a depth of 200 nm is used, the press pressure is 2 kgf / cm 2, the roll temperature is 80 ° C., the press speed is 10 m / min. Molded. Simultaneously with molding, exposure was performed at 300 mJ / cm 2 with a high-pressure mercury lamp, and the shape was transferred and cured at the same time. At this time, the release layer was also cured, the tackiness of the release layer was lowered, and the peel strength was lowered, so that the fine relief pattern forming layer adhered to the relief original plate, and the relief plate was stained. Shape transfer was impossible.

  The optical element transfer foil of the present invention can be applied to various articles with high productivity in the manner of hot stamping, and is used as an anti-counterfeit optical member such as banknotes and ID cards.

DESCRIPTION OF SYMBOLS 1 ... Optical element transfer foil 2 ... Film base material 3 ... Release layer 4 ... Fine relief pattern formation layer 10 ... Laminated body before relief pattern shaping | molding (radiation non-irradiation)
DESCRIPTION OF SYMBOLS 11 ... Relief pattern original plate 12 ... Press roll 13 ... Radiation irradiation machine 14 ... Radiation irradiation machine 20 ... Laminated body after relief pattern molding (radiation irradiation completed)

Claims (6)

  An optical element transfer foil in which at least a film-like substrate, a release layer obtained by curing the first radiation-curable resin, and a relief pattern layer obtained by curing the second radiation-curable resin are laminated in this order. An optical element transfer foil, wherein a wavelength of radiation obtained by curing the first radiation curable resin is shorter than a wavelength of radiation obtained by curing the second radiation curable resin. 2. The optical element transfer foil according to claim 1, wherein the first radiation curable resin has a tack property before radiation irradiation and a tack-free property after radiation irradiation. 3. The optical element transfer foil according to claim 1, wherein the first radiation curable resin includes an electron beam curable resin, and the second radiation curable resin includes an ultraviolet curable resin. 4.   The optical element transfer foil according to any one of claims 1 to 3, wherein the relief pattern in the relief pattern layer has an aspect ratio of 0.5 or more.   5. The optical element transfer foil according to claim 1, wherein the relief pattern in the relief pattern layer has a sub-wavelength structure equal to or less than a wavelength of light. A step of applying a first radiation curable resin and a second radiation curable resin to the surface of the film-shaped substrate to form a laminate,
Biting a relief mold having a relief pattern into the second radiation curable resin of the laminate; and
Irradiating the second radiation curable resin of the laminate with radiation to cure only the second radiation curable resin; and
Peeling the laminate from the relief mold;
And a step of irradiating the first radiation curable resin of the laminate with radiation to cure the optical element transfer foil.

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