JP2009157287A - Manufacturing method of diffraction structure formation body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method to manufacture a diffraction structure formation body in which the pattern by the diffraction structure and the pattern by a metal layer are in agreement without positioning. <P>SOLUTION: This manufacturing method includes a process to form a diffraction structure on part of base material surface, a process to form a metal layer 13 on the entire surface where the diffraction structure is formed, irradiate laser light onto the entire surface of the metal layer in single lines or in dot-like shape, and selectively destroy part of the metal layer 13 on the diffraction structure using absorption in the diffraction structure, a process to form a photoresist 18 on the entire surface where the diffraction structure is formed, cure the photoresist on the diffraction structure by irradiating diffraction light generated by making exposure light 19 passing through a portion where part of the metal layer is selectively destroyed, develop the photoresist and form a resist pattern covering the diffraction structure, and a process to etch the resist pattern as a mask, and remove the metal layer other than the diffraction structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a diffractive structure forming body.

  Conventionally, in order to produce a diffractive structure forming body having a metal layer as a reflection layer, for example, a hologram, a method of patterning the metal layer is used to form a high-definition contour. Such holograms are not only improved in design but also have a counterfeit prevention effect, and are used in banknotes and ID media in many countries and regions.

As a method of forming a metal layer pattern on such a diffractive structure forming body,
(1) A printing method in which an etching mask or washing ink is printed by gravure or screen, and realized by etching or sealight processing,
(2) A laser method in which the reflective layer is destroyed by heating directly above the melting point of the metal layer with a laser,
(3) A photolithographic method realized by pattern exposure through a photomask on a photoresist formed on a metal reflective layer, development, and etching;
Etc.
Japanese Patent Application No. 3-313280 JP 2003-043333 A JP 2003-255115 A

  When the pattern formed by patterning the metal layer and the pattern formed by the diffractive structure are aligned, the design and anti-counterfeiting effect are further improved according to the accuracy.

  However, in the conventional method, when the reflective layer is patterned, there is a problem that the position varies with respect to the diffractive structure due to the influence of positioning accuracy, processing accuracy, expansion and contraction of the base material, and the like.

  An object of the present invention is to provide a method capable of producing a diffractive structure formed body in which the pattern of the diffractive structure and the pattern of the metal layer are uniformly processed on the entire surface without distinction, and the positions of both patterns are aligned without alignment. It is to provide.

  The invention according to claim 1 includes a step of forming a diffractive structure on a part of a substrate surface, a metal layer is formed on the entire surface on which the diffractive structure is formed, and a laser beam is applied to the entire surface of the metal layer. A step of selectively destroying a part of the metal layer on the diffractive structure using absorption in the diffractive structure, and forming a photoresist on the entire surface on which the diffractive structure is formed. Irradiating the photoresist with diffracted light generated by passing exposure light through a portion where a part of the metal layer is selectively destroyed, curing the photoresist on the diffractive structure, and developing the diffractive structure. A method of manufacturing a diffractive structure forming body, comprising: a step of forming a resist pattern covering the substrate; and a step of performing etching using the resist pattern as a mask to remove a metal layer in a portion other than the diffractive structure.

  The invention according to claim 2 is the method for producing a diffractive structure forming body according to claim 1, wherein the photoresist contains a light scattering component.

  The invention according to claim 3 is the method for producing a diffractive structure forming body according to claim 1 or 2, wherein after the reflective layer is formed on the photoresist, exposure light is irradiated.

  According to the present invention, it is possible to manufacture a diffractive structure forming body in which uniform processing is performed on the entire surface without distinguishing between a pattern formed by a diffractive structure and a pattern formed by a metal layer, and the positions of both patterns are aligned without alignment.

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

  1-5 is sectional drawing which shows an example of the manufacturing method of the diffraction structure formation body by this invention. As shown in FIG. 1, a diffractive structure forming layer (12) is provided on a substrate (11), and a diffractive structure is formed on a part of the surface of the diffractive structure forming layer (12). The entire surface of the diffractive structure forming layer (12) on which the diffractive structure is formed is covered with the metal layer (13). FIG. 1 shows a diffractive structure forming portion (14) and the other mirror surface portion (15) of the metal layer (13).

  The diffraction structure formed body in the present invention will be described. The diffractive structure forming body is generally divided into a hologram and a diffraction grating.

  For holograms, a relief-type master plate consisting of a fine concavo-convex pattern is produced by an optical imaging method, and a nickel-made press plate is produced by duplicating the concavo-convex pattern by electroplating from this master plate. Mass replication is carried out by embossing in which the substrate (11) or the diffraction structure forming layer (12) is heated and pressed. This type of hologram is called a relief hologram.

  Unlike holograms that capture such actual images, diffraction gratings use multiple simple diffraction gratings in a small area as pixels, grating images, dot matrices (pixelgrams, etc.) Represents an image called. An image using such a diffraction grating is mass-replicated in the same manner as a relief hologram.

  A diffractive structure and a smooth portion are formed by a stamper. These portions become the diffraction structure forming portion (14) and the mirror surface portion (15) when the metal film (13) is formed.

  As a material of the base material (11), a stretched or non-stretched transparent film such as polyethylene, polypropylene, PET, PEN or the like can be used.

  The diffraction structure forming layer (12) is provided when it is difficult to directly emboss the base material (11). As the diffractive structure forming layer (12), a curable resin such as a thermoplastic resin such as acrylic, urethane or vinyl chloride vinyl acetate copolymer, a two-component curable urethane obtained by curing melamine, acrylic polyol or polyester polyol with isocyanate. Can be used. As means for providing on the substrate, known methods such as gravure coating, micro gravure coating, die coating, spin coating and the like can be used.

  In the diffractive structure forming body, a metal layer (13) is formed on the surface of the relief in order to increase the luminance. The metal layer (13) is formed by vapor deposition and sputtering of Al, Sn, Ni, Cu, Au or the like.

  The diffractive structure forming portion (14) is formed with striped irregularities of 0.5 to 2.0 μm. The light having the same wavelength as the fringe pitch has an improved absorptance in the diffractive structure forming portion (14) compared to the mirror surface portion (15). Here, in the case where the diffractive structure is formed with rectangular stripes having a spatial frequency of 1,000 L / mm and a depth of 120 nm and an Al layer is formed as a metal layer, a simulation using a FDTD (finite difference time domain) method is performed. Results are shown. When the fundamental wave of the Nd: YAG laser of 1064 nm is irradiated, the absorptance of the diffraction structure forming portion (14) is 21.5%, but the absorptivity of the specular portion (15) is 10.0%. is there. That is, the diffractive structure forming portion (14) is more likely to absorb light twice or more than the mirror surface portion (15). By using polarized light orthogonal to the fringes of the diffractive structure, it is possible to make a greater difference in the absorptance between the two portions.

  Next, as shown in FIG. 2, a laser beam (16) is irradiated from the base material (11) side in the form of lines or dots so as to cover the entire surface of the metal layer (13), thereby forming a diffraction structure. Only a part of the metal layer of the part (14) is selectively destroyed to form a metal layer destroyed part (17). Laser irradiation may be performed from the metal layer (13) side.

  At this time, by utilizing the difference in the absorptivity between the diffraction structure forming portion (14) and the mirror surface portion (15), a part of the metal layer is broken only by the diffraction structure forming portion (14), and the mirror surface portion (25). It is possible to perform processing without changing the metal layer.

  As the laser, an existing laser such as an Nd: YAG laser, a carbon dioxide gas laser, or a laser diode can be used. The destruction by the laser may be from the substrate side or the metal layer side.

  Next, as shown in FIG. 3, a negative resist (18) is formed on the entire surface of the diffraction structure forming layer (12) on which the diffraction structure is formed. Optionally, a negative resist (18) may be formed before laser light irradiation. The exposure light (19) having a wavelength for curing the negative resist (18) is irradiated from the substrate (11) side. The remaining metal layer (13) functions as a photomask, and the exposure light (19) reaches the negative resist (18) through the metal layer destruction portion (17). At this time, the exposure light (19) is diffracted by the diffraction structure and wraps around, and the negative resist (18) around the metal layer destruction portion (17) is also cured. As a result, the negative resist (18) covering the diffractive structure is cured.

  As the negative resist (18), a known resist such as an alkali developing radical polymerization acrylate can be used. The thickness of the resist is preferably 1 to 100 μm. For the resist coating, a gravure coating method, a micro gravure coating method, a die coating method, a spin coating method, a dip coating method, or the like can be used. The exposure machine may be a known one using a general mercury lamp, excimer lamp or the like.

  Next, as shown in FIG. 4, the negative resist (18) is developed to form a resist pattern (20) that covers the diffractive structure. For the development, a developer suitable for the resist is used, and suitable conditions are selected.

  Finally, as shown in FIG. 5, the metal layer of the mirror surface portion (15) other than the diffractive structure exposed from the resist pattern (20) was removed by etching, and the pattern of the diffractive structure and the pattern of the metal layer were aligned. A diffractive structure forming body is manufactured.

  Etching is performed under an appropriate processing condition using an etching agent suitable for the metal used for the reflective layer. When an amphoteric metal such as Al is used for the metal layer and an alkali development type is used for the resist, development and etching can be performed in the same process.

  The processing conditions in the manufacturing method of the diffractive structure forming body having the positions of the pattern by the diffraction structure and the pattern by the metal layer described above will be described in detail. The metal part of the diffractive structure forming part is destroyed by the laser, but the undestructed part is finally used as the reflective layer of the diffractive structure forming part, so the area ratio of the destroyed part and the undestructed part is carefully designed Should. In order for the hardened part of the resist due to the wraparound of light to cover all of the diffractive structure during exposure, the metal layer is destroyed by laser irradiation so as to form a periodic structure such as a line shape or a dot shape. Is desirable. The period at which the metal layer is broken is set according to the hardening width caused by the wraparound.

  By adding a light scattering component such as a filler to the resist and using scattered light as a light source, the wraparound width can be increased. Moreover, exposure light can be used effectively by providing a reflective layer on the back surface of the resist. At the same time, the inhibition of curing by oxygen can be prevented by the gas barrier property of the reflective layer.

  The visibility of the diffractive structure decreases as the fracture area ratio of the metal layer in the diffractive structure forming portion increases, but the illuminance during resist curing can be decreased. Further, as the destruction area ratio of the metal layer of the diffraction structure forming portion increases, a visual effect such as printing provided on the base can be provided. The destruction period is preferably 1 to 100 μm, and the destruction area ratio is preferably 10% to 90%. In order to realize a periodic structure with a laser, a scanning method using a galvanoscan laser or a method of irradiating through a lens such as a photomask, a lenticular lens, or a microlens array can be used.

  The diffractive structure formed body produced by the method of the present invention can be applied to various uses.

  FIG. 6 shows an embodiment as a sticker in which an adhesive layer (31) is provided on the diffractive structure forming body shown in FIG.

  Thus, by providing the adhesive layer (31) on the back surface of the diffractive structure forming body, a polarization latent image sticker can be obtained. Moreover, a pasting prevention function can be provided by putting cutting into a base material (11) or forming a brittle layer.

  In FIG. 7, a peeling layer (41) is provided between the base material (11) and the diffraction structure forming layer (12) of the diffraction structure forming body shown in FIG. ) Is an embodiment as a transfer foil provided.

  Such a transfer foil can be transferred by being peeled off from the substrate after being adhered to the transfer target by a roll transfer machine or a hot stamp. A peeling layer (41) is added when the base material (11) and the diffraction structure forming layer (12) cannot be peeled stably.

  Acrylic, styrene, nitrified cotton, or the like can be used for the release layer (41), and processing is performed using a known method such as a gravure coating method or a micro gravure coating method, as with other layers.

  FIG. 8 shows an embodiment as a thread of the diffractive structure forming body shown in FIG.

  Microslit the diffractive structure forming body, and spread it with a window opening so that a part can be seen on the paper. By applying an adhesive process to this interleaving paper, it can also be used as a sticker for a substrate or package of a securities medium.

  A peeling protective layer made of an acrylic resin was coated on a PET film having a thickness of 25 μm to a thickness of 1 μm by a gravure coating method. A diffractive structure forming layer obtained by adding an equal amount of HMDI-based isocyanate to acrylic polyol was further coated with a thickness of 1 μm by gravure coating. A stamper having a diffractive structure and a smooth portion was pressed on the diffractive structure forming layer at 200 ° C. and 1 MPa to emboss and replicate the shape. On the diffraction structure forming layer, Al was formed as a metal layer with a thickness of 50 nm using a vacuum deposition method. Using a galvano scan laser with a wavelength of 1064 nm from the substrate side, the entire surface of the diffractive structure forming layer is irradiated with a width of 5 μm at a period of 20 μm with an illuminance that destroys only the diffractive structure part. The metal layer was broken into a shape.

10 μm of an alkali developing negative resist added with a silica filler was applied to the entire surface of the diffractive structure forming layer on which the diffractive structure was formed. An Al reflective layer was formed to a thickness of 50 nm on the negative resist by vacuum deposition. Using a diffused light type exposure machine with a mercury light source from the substrate side, it was cured at an illuminance of 500 mJ / cm ² and developed using a 5% aqueous sodium carbonate solution at 30 ° C. to form a resist pattern covering the diffraction structure. Using the resist pattern as an etching mask, the metal layer on the mirror surface other than the diffraction structure was etched.

  Further, an adhesive layer made of a vinyl chloride / vinyl acetate copolymer was applied by a gravure coating method to obtain a transfer foil.

  The obtained transfer foil was transferred to paper at 130 ° C. and 10 MPa using a hot stamp. The obtained transfer product was a medium having high design properties and anti-counterfeiting effects because the pattern of the diffraction structure and the pattern of the metal layer were aligned.

Sectional drawing which shows 1 process of the manufacturing method of the diffraction structure formation body which concerns on this invention. Sectional drawing which shows 1 process of the manufacturing method of the diffraction structure formation body which concerns on this invention. Sectional drawing which shows 1 process of the manufacturing method of the diffraction structure formation body which concerns on this invention. Sectional drawing which shows 1 process of the manufacturing method of the diffraction structure formation body which concerns on this invention. Sectional drawing which shows 1 process of the manufacturing method of the diffraction structure formation body which concerns on this invention. Sectional drawing which shows embodiment which applies the diffraction structure formation body which concerns on this invention as a sticker. Sectional drawing which shows embodiment which applies the diffraction structure formation body which concerns on this invention as transfer foil. Sectional drawing which shows embodiment which applies the diffraction structure formation body which concerns on this invention as a thread | sled.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Base material, 12 ... Diffraction structure formation layer, 13 ... Metal layer, 14 ... Diffraction structure formation part, 15 ... Mirror surface part, 16 ... Laser beam, 17 ... Metal layer destruction part, 18 ... Negative resist, 19 ... Exposure Light, 20 ... resist pattern, 21 ... metal layer pattern, 31 ... adhesive layer, 41 ... release layer, 42 ... adhesive layer.

Claims (3)

Forming a diffractive structure on a part of the substrate surface;
A metal layer is formed on the entire surface on which the diffractive structure is formed, a laser beam is irradiated on the entire surface of the metal layer in a line shape or a halftone dot shape, and the metal layer on the diffractive structure is absorbed using the diffraction structure. A step of selectively destroying a part of
The photoresist is formed on the entire surface where the diffractive structure is formed, and the diffraction is generated by irradiating the photoresist with diffracted light generated by passing exposure light through a portion where a part of the metal layer is selectively destroyed. Curing a structural photoresist and developing to form a resist pattern covering the diffractive structure;
Etching with the resist pattern as a mask, and removing a metal layer in a portion other than the diffractive structure.   The method for manufacturing a diffractive structure forming body according to claim 1, wherein the photoresist contains a light scattering component.   The method for producing a diffractive structure forming body according to claim 1, wherein exposure light is irradiated after forming a reflective layer on the photoresist.

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