JP2023103215A - Volume hologram laminate, volume hologram transfer foil, volume hologram label, card, data page and book - Google Patents

Abstract

To provide a volume hologram laminate which has the high forgery prevention effect.SOLUTION: A volume hologram laminate has a substrate and a volume hologram laminate section positioned on one surface of the substrate, wherein: the volume hologram laminate section has a volume hologram layer which contains a polymer of a photopolymerizable compound and on which an interference fringe is recorded, and also has a resin layer containing a transparent resin and positioned next to the volume hologram layer, said layers being arranged in random order; and the read-out wavelength of the volume hologram layer changes according to the observation angle and incidence angle of the reproduced illuminating light, and the color of the reproduced image from the volume hologram layer also changes according thereto.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a volume hologram laminate having a volume hologram layer on which interference fringes are recorded, and a volume hologram transfer foil, a volume hologram label, a card, a data page, and a booklet using the volume hologram laminate.

A hologram is obtained by causing interference between two lights (object light and reference light) having the same wavelength and recording the wavefront of the object light as interference fringes on a photosensitive material. When this hologram is irradiated with light under the same conditions as the reference light used when recording the interference fringes, a diffraction phenomenon occurs due to the interference fringes, and the same wavefront as the original object light can be reproduced. Holograms are often used for security applications and the like because they have advantages such as a beautiful appearance and being relatively difficult to duplicate.

Holograms can be classified into several types according to the recording form of interference fringes, and typically can be divided into surface relief holograms and volume holograms. A surface relief hologram is a hologram layer having a fine uneven pattern formed on its surface. On the other hand, in a volume hologram, interference fringes generated by light interference are three-dimensionally recorded in the thickness direction as fringes with different refractive indices. Volume holograms are images recorded by the difference in refractive index of materials, and are therefore more difficult to replicate than surface relief holograms.

A volume hologram can be industrially mass-produced using a hologram master. Therefore, the volume hologram itself can be used as a master plate, a photosensitive material for duplication is brought into close contact with the volume hologram, and a laser beam is irradiated from the photosensitive material side to enable duplication.

On the other hand, the current situation is that the wavelength of laser light used industrially is limited. Therefore, by changing the reproduction wavelength of the volume hologram, it is possible to prevent duplication by the above method. In other words, the reproduction wavelength of the volume hologram should be shifted to a wavelength where no laser light source exists. In this case, the reproduction wavelength of the volume hologram may be shifted to either the long wavelength side or the short wavelength side.

For example, Patent Document 1 discloses a method of bringing a hologram layer into contact with a diffusing element containing a monomer, migrating the monomer to the hologram layer, causing the hologram layer to swell, and changing the response wavelength of the volume phase reflection to a longer wavelength. Further, Patent Document 2 discloses a method of shifting the reproduction wavelength of the volume hologram layer to the longer wavelength side by bringing a resin layer containing a resin and a polymerizable compound into contact with the volume hologram layer to transfer the polymerizable compound in the resin layer to the volume hologram layer.

Further, for example, Patent Document 3 discloses a method of shifting the reproduction wavelength of the volume hologram layer to the short wavelength side by bringing the volume hologram layer into contact with a wavelength shift layer composed of thermoplastic organic fine particles and a binder to transfer low-molecular-weight substances in the volume hologram layer to the wavelength shift layer.

By the way, as described above, holograms have been used for security applications because they are relatively difficult to duplicate. However, in recent years, techniques for easily duplicating holograms have begun to spread, and it has been pointed out that simply using holograms alone is insufficient as an anti-counterfeiting means.

Japanese Patent No. 3170357 Japanese Patent No. 5251167 Japanese Patent No. 4121767

The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a volume hologram laminate having a high anti-counterfeiting effect.

An embodiment of the present disclosure is a volume hologram laminate having a substrate and a volume hologram laminate disposed on one surface of the substrate, wherein the volume hologram laminate contains a polymerized product of a photopolymerizable compound and has a volume hologram layer in which interference fringes are recorded, and a resin layer containing a transparent resin, disposed in contact with the volume hologram layer, in random order, and the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, so that the reproduced image from the volume hologram layer changes. To provide a volume hologram laminate that changes color.

In the volume hologram laminate of the present embodiment, when the incident angle and first observation angle of the first reconstruction illumination light are gradually changed to the second reconstruction illumination light incident angle and second observation angle, it is preferable that the reproduction wavelength of the volume hologram layer gradually changes.

Another embodiment of the present disclosure provides a volume hologram laminate having a substrate and a volume hologram laminate disposed on one surface of the substrate, wherein the volume hologram laminate includes a polymerized product of a photopolymerizable compound and includes, in random order, a volume hologram layer in which interference fringes are recorded, and a resin layer that is arranged in a pattern in contact with the volume hologram layer and contains a transparent resin.

In the volume hologram laminate of the present embodiment, the color of the reproduced image from the volume hologram layer may be different between the resin layer forming region where the resin layer is arranged and the resin layer non-forming region where the resin layer is not arranged.

Further, in the volume hologram laminate of the present embodiment, in the resin layer forming region where the resin layer is arranged, the reproduction wavelength of the volume hologram layer may change according to the incident angle and observation angle of the reproduction illumination light, and the color of the reproduced image from the volume hologram layer may change.

In the above case, when the incident angle and first observation angle of the first reconstruction illumination light are gradually changed to the second reconstruction illumination light incident angle and second observation angle, it is preferable that the reproduction wavelength of the volume hologram layer gradually changes in the resin layer forming region.

Another embodiment of the present disclosure provides a volume hologram transfer foil having the volume hologram laminate described above and a heat seal layer disposed on the surface of the volume hologram laminate on the side of the volume hologram laminate.

In the volume hologram transfer foil according to the present disclosure, the volume hologram laminate preferably has a release layer between the volume hologram laminate and the base material.

Another embodiment of the present disclosure provides a volume hologram label including the volume hologram laminate described above and an adhesive layer disposed on the surface of the volume hologram laminate on the side of the volume hologram laminate.

Another embodiment of the present disclosure provides a card having a core sheet, an adhesive layer, the volume hologram laminate described above, and a transparent sheet in this order.

Another embodiment of the present disclosure provides a data page having, in order, a first transparent sheet, an IC chip holding sheet containing an IC chip therein, a core sheet, an adhesive layer, the volume hologram laminate described above, and a second transparent sheet.

Other embodiments of the present disclosure provide brochures comprising the data pages described above.

In the present disclosure, it is possible to provide a volume hologram laminate with a high anti-counterfeiting effect.

1 is a schematic cross-sectional view illustrating a volume hologram laminate in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a volume hologram laminate in the present disclosure; FIG. FIG. 4 is a schematic diagram illustrating a method for reproducing a volume hologram laminate in the present disclosure; FIG. 4 is a process diagram illustrating a method for manufacturing a volume hologram laminate according to the present disclosure; 1 is a schematic cross-sectional view illustrating a volume hologram laminate in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a volume hologram laminate in the present disclosure; FIG. FIG. 4 is a schematic diagram illustrating a method for reproducing a volume hologram laminate in the present disclosure; 1 is a schematic cross-sectional view illustrating a volume hologram transfer foil in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a volume hologram transfer foil in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a volume hologram label in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a volume hologram label in the present disclosure; FIG. 1A and 1B are schematic plan and cross-sectional views illustrating cards in the present disclosure; 1 is a schematic cross-sectional view illustrating a card in the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a data page in the present disclosure; FIG. 1 is a schematic perspective view illustrating brochures in the present disclosure; FIG. 4 is a photograph of the volume hologram laminate of Example 1. FIG. 4 is a photograph of a volume hologram laminate of Comparative Example 1. FIG.

Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be embodied in many different modes and should not be construed as limited to the description of the embodiments exemplified below. In addition, in order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual form, but it is only an example and does not limit the interpretation of the present disclosure. In addition, in this specification and each figure, the same reference numerals may be given to the same elements as those described above with respect to the existing figures, and detailed description thereof may be omitted as appropriate.

In this specification, when expressing a mode of arranging another member on top of a certain member, the term “above” or “below” shall include both the case of arranging another member directly above or below so as to be in contact with a certain member, and the case of arranging another member above or below a certain member via another member, unless otherwise specified. Further, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, unless otherwise specified, the term “on the surface” includes both the case of arranging another member directly above or directly below a certain member and the case of arranging another member above or below a certain member via another member, unless otherwise specified.

In this specification, the term "sheet" also includes a member called "film". The term "film" also includes members called "sheets".

The volume hologram laminate, volume hologram transfer foil, volume hologram label, card, data page, and booklets in the present disclosure will be described in detail below.

A. Volume Hologram Laminate The volume hologram laminate in the present disclosure has two embodiments. Each embodiment will be described below.

I. First Embodiment A first embodiment of the volume hologram laminate in the present disclosure has a substrate and a volume hologram laminate disposed on one surface of the substrate, the volume hologram laminate includes a volume hologram layer containing a polymer of a photopolymerizable compound and having interference fringes recorded therein, and a resin layer containing a transparent resin disposed in contact with the volume hologram layer in random order. The color of the reproduced image changes.

The volume hologram laminate of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the volume hologram laminate of this embodiment. As illustrated in FIG. 1 , the volume hologram laminate 10 has a substrate 1 and a volume hologram laminate 2 arranged on one surface of the substrate 1 . The volume hologram laminate section 2 includes, in random order, a volume hologram layer 2a containing a polymer of a photopolymerizable compound and having interference fringes recorded thereon, and a resin layer 2b disposed in contact with the volume hologram layer 2a and containing a transparent resin.

In FIG. 1, the volume hologram laminate 2 has the resin layer 2b and the volume hologram layer 2a in order from the substrate 1 side, but as shown in FIG. 2, the volume hologram laminate 2 may have the volume hologram layer 2a and the resin layer 2b in order from the substrate 1 side.

In the volume hologram laminate of this embodiment, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the reproduced image from the volume hologram layer changes.

FIGS. 3A and 3B are schematic diagrams for explaining the method of reproducing the volume hologram laminate of this embodiment. The structure of the volume hologram laminate 10 illustrated in FIGS. 3A and 3B is the same as the structure of the volume hologram laminate 10 illustrated in FIG. 1 above.

First, as shown in FIG. 3A, an observer observes the volume hologram laminate 10 from an observation direction D1 that is 0° with respect to the normal direction d of the surface of the volume hologram laminate 10 while the reconstruction illumination light L having a predetermined incident angle θ1 with respect to the normal direction d of the surface of the volume hologram laminate 10 is irradiated. At this time, for example, when the recording wavelength during interference fringe recording is in the green wavelength range, the incident angle θ1 of the reproduction illumination light L is substantially the same as the incident angle of the reference light during interference fringe recording, and the observation angle (the angle in the observation direction D1) is substantially the same as the incident angle of the object light during interference fringe recording, the observer can observe a green reproduced image similar to the color of the recording wavelength during interference fringe recording.

Next, as shown in FIG. 3B, an observer observes the volume hologram laminate 10 from an observation direction D2 having a predetermined observation angle θ4 with respect to the normal direction d of the surface of the volume hologram laminate 10 while the reconstruction illumination light L having a predetermined incident angle θ3 with respect to the normal direction d of the surface of the volume hologram laminate 10 is irradiated. At this time, for example, when the recording wavelength during interference fringe recording is in the green wavelength range, the incident angle θ3 of the reproducing illumination light L is larger than the incident angle θ1 of the reproducing illumination light L shown in FIG. 3A, and the observation angle θ4 is greater than the observation angle shown in FIG.

Here, in the production of the volume hologram laminate, for example, after interference fringes are recorded in the volume hologram layer, a resin layer is placed in contact with the volume hologram layer, and a low-molecular-weight substance such as an uncured photopolymerizable compound contained in the volume hologram layer is transferred to the resin layer. This shrinks the volume hologram layer and narrows the interval between the interference fringes.

At this time, for example, if the amount of shift in the reproduction wavelength is large, even if the incident angle of the reproduction illumination light is made substantially the same as the incidence angle of the reference light during interference fringe recording, and the observation angle is substantially the same as the incidence angle of the object light during interference fringe recording, it is not possible to observe a reproduced image having the same color as the recording wavelength, but a reproduced image having a different color from the recording wavelength is observed. Even in this case, a reproduced image with a color different from the recording wavelength is observed. On the other hand, for example, if the amount of shift of the regenerative wavelength is small, the entry angle of the recycling lights is the same as the incident angle of the light in the interference at the time of recording, and the observation angle is abbreviated as the incident angle of the object light at the time of recording interference in interference. See the globe of lighting light. Reference at the time of interference stripes at the time of recording of interference, and even if the observation angle is larger than the observation angle than the instruction angle of the object light at the time of interference plastic light, the same color regeneration image will be observed as the recording wavelength. In such a case, the color of the reproduced image from the volume hologram layer cannot be changed according to the incident angle and observation angle of the reconstruction illumination light.

On the other hand, by appropriately controlling the amount of shift in the reproduction wavelength, when the incident angle of the reproduction illumination light is made substantially the same as the incident angle of the reference light during interference fringe recording, and the observation angle is substantially equal to the incident angle of the object light during interference fringe recording, a reproduced image with the same color as the recording wavelength is observed. can be made Therefore, in this embodiment, by controlling the shift amount of the reproduction wavelength of the volume hologram layer, the color of the reproduced image from the volume hologram layer can be changed according to the incident angle and observation angle of the reproduction illumination light.

Generally, in a volume hologram, when monochromatic laser light is used to record interference fringes, the reproduced image is monochromatic. On the other hand, in the volume hologram laminate of the present embodiment, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the image reproduced from the volume hologram layer changes, so the anti-counterfeiting effect can be enhanced. Furthermore, for example, by controlling the shift amount of the reproduction wavelength of the volume hologram layer and shifting the reproduction wavelength of the volume hologram layer to a wavelength where no laser light source exists, duplication becomes difficult, so the anti-counterfeiting effect can be further enhanced.

In addition, in the volume hologram laminate of this embodiment, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the image reproduced from the volume hologram layer changes.

In addition, in the volume hologram laminate of this embodiment, the volume hologram layer and the resin layer are in contact with each other. For example, after recording interference fringes in the volume hologram layer, the resin layer is arranged in contact with the volume hologram layer, and a low-molecular-weight substance such as an uncured photopolymerizable compound contained in the volume hologram layer is transferred to the resin layer, whereby the volume hologram laminate can be produced. Therefore, even though the monochromatic laser beam is used to record interference fringes, it is possible to obtain a volume hologram laminate in which the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the image reproduced from the volume hologram layer changes. Furthermore, it is possible to obtain a volume hologram laminate with a high anti-counterfeiting effect by a simple method.

Each configuration of the volume hologram laminate of this embodiment will be described below.

1. Characteristics of Volume Hologram Laminate In the volume hologram laminate of this embodiment, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the reproduced image from the volume hologram layer changes.

The reproduction wavelength of the volume hologram layer is usually in the visible light region, for example, 380 nm or more and 780 nm or less. Above all, the reproduction wavelength of the volume hologram layer is preferably a wavelength at which no laser light source exists. Since duplication becomes difficult, the anti-counterfeiting effect can be further enhanced.

Here, the wavelengths at which the laser light source exists include, for example, blue wavelengths of 460 nm, 477 nm and 488 nm; green wavelengths of 515 nm and 532 nm; red wavelengths of 633 nm and 647 nm.

The color of the reproduced image from the volume hologram layer, that is, the reproduced color, may be any color that can be identified by the human eye.

When the color of the reconstructed image from the volume hologram layer changes depending on the incident angle and observation angle of the reconstruction illumination light, all the colors of the reconstructed image are preferably colors with similar wavelengths, such as a combination of green and blue, or a combination of blue and bluish purple or violet. In this embodiment, as described above, by appropriately controlling the shift amount of the reproduction wavelength of the volume hologram layer, the color of the image reproduced from the volume hologram layer can be changed according to the incident angle and observation angle of the reproduction illumination light. In this case, the colors of the reproduced images before and after the change have similar wavelengths. On the other hand, if the color of the reproduced image before and after the change is a color with a distant wavelength, such as a combination of green and red, it is necessary to increase the shift amount of the reproduced wavelength of the volume hologram layer. However, as described above, if the amount of shift in the reproduction wavelength of the volume hologram layer is large, there is a possibility that the color of the reproduced image from the volume hologram layer cannot be changed according to the incident angle and observation angle of the reproduction illumination light. Therefore, it is extremely difficult to form a volume hologram layer in which the wavelength of the reproduced image before and after the change is a distant color.

Further, when the color of the reproduced image from the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, one of the colors of the reproduced image before and after the change is preferably similar to the color of the wavelength at which the laser light source exists, that is, preferably similar to the color of the recording wavelength. In this embodiment, as described above, by appropriately controlling the shift amount of the reproduction wavelength of the volume hologram layer, the color of the image reproduced from the volume hologram layer can be changed according to the incident angle and observation angle of the reproduction illumination light. In order to control the shift amount of the reproduction wavelength of the volume hologram layer in this way, it is preferable to make one of the colors of the reproduction image before and after the change similar to the color of the recording wavelength. For example, when the amount of shift in the reproduction wavelength of the volume hologram layer is relatively small, even if the reproduction wavelength is shifted to the shorter wavelength side than the recording wavelength, one of the colors of the reproduced image before and after the change can be made similar to the color of the recording wavelength.

Here, examples of the color of the wavelength at which the laser light source exists include blue, green, red, and the like.

For example, when the wavelength at which the laser light source exists is blue, the similar color is blue; when the wavelength at which the laser light source is present is green, the similar color is green; and when the wavelength at which the laser light source is present is red, the similar color is red. Similarly, the color similar to the color of the recording wavelength means, for example, when the color of the recording wavelength is blue, the similar color is blue, when the color of the recording wavelength is green, the similar color is green, and when the color of the recording wavelength is red, the similar color is red.

In this embodiment, since the reproduction wavelength of the volume hologram layer is shifted to the short wavelength side when the volume hologram layer is formed, one of the colors of the reproduced image before and after the change is similar to the color of the wavelength at which the laser light source exists, that is, if it is similar to the color of the recording wavelength, the other color is preferably the color on the shorter wavelength side than the wavelength at which the laser light source exists, that is, the color on the shorter wavelength side than the recording wavelength.

Therefore, when the color of the reproduced image from the volume hologram layer changes depending on the incident angle and observation angle of the reproduction illumination light, it is preferable that all the colors of the reproduced image are colors with wavelengths close to each other, and among the colors of the reproduced image before and after the change, one color is similar to the color of the wavelength at which the laser light source exists, that is, the color of the recording wavelength, and the other color is preferably the color that is shorter than the wavelength at which the laser light source exists, that is, the color that is shorter than the recording wavelength. Such color combinations of reproduced images before and after change include, for example, a combination of blue and purple or bluish purple; a combination of green and blue; a combination of red and orange or yellow. For example, a combination of blue and purple can change to blue, blue-violet, and purple before, during, and after the change. Also, for example, green and blue can be changed to green, blue-green, and blue before, during, and after change. Among others, since humans have high sensitivity in the green wavelength range, the combination of colors of the reproduced image before and after the change is preferably a combination of green and blue.

Moreover, when the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, all the reproduction wavelengths are preferably wavelengths at which the laser light source does not exist, as described above. In this case, the reproduction wavelength is selected appropriately according to the desired color as long as it can express the desired color.

Here, the reproduction wavelength is the wavelength that appears brightest when observed at an arbitrary viewing angle, that is, the peak wavelength.

Further, in this embodiment, the reproduction wavelength of the volume hologram layer changes and the color of the reproduced image from the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light. By adjusting at least one of the incident angle and observation angle of the reproduction illumination light, the reproduction wavelength of the volume hologram layer can be changed, and the color of the reproduced image from the volume hologram layer can be changed. At this time, for example, both the incident angle of the reconstruction illumination light and the observation angle may be adjusted, the incident angle of the reconstruction illumination light may be fixed and only the observation angle may be adjusted, or the observation angle may be fixed and only the incident angle of the reconstruction illumination light may be adjusted.

For example, when the color of the reproduced image from the volume hologram layer when observed at the incident angle of the first reconstruction illumination light and the first observation angle is set as the first color, and the color of the reproduced image from the volume hologram layer when observed at the incident angle of the second reconstruction illumination light and the second observation angle is set as the second color, and the second color is a color on the shorter wavelength side than the first color, the incident angle of the reconstruction illumination light may be fixed and changed from the first observation angle to the second observation angle. Alternatively, the first color may be changed to the second color by fixing the observation angle and changing the incident angle of the first reconstruction illumination light to the second reconstruction illumination light.

Among them, when the color of the reproduced image from the volume hologram layer observed at the incident angle of the first reconstruction illumination light and the first observation angle is set as the first color, and the color of the reproduced image from the volume hologram layer when observed at the incident angle of the second reconstruction illumination light larger than the incident angle of the first reconstruction illumination light and the second observation angle larger than the first observation angle is assumed to be the second color, the second color is preferably a color on the shorter wavelength side than the first color.

In this case, the first color is preferably a color similar to the color of the recording wavelength. Also, in this case, the second color is preferably a color on the shorter wavelength side than the recording wavelength. Note that the combination of the first color and the second color is the same as the color combination of the reproduced image before and after the change described above.

Further, in the above case, the incident angle of the first reproduction illumination light can be substantially the same as the incident angle of the reference light during interference fringe recording, for example. The incident angle of the first reconstruction illumination light is usually 0° or more.

Further, in the above case, the first observation angle can be substantially the same as the incident angle of the object light during interference fringe recording, for example. Note that the first observation angle is usually 0° or more.

On the other hand, in the above case, the incident angle of the second reconstruction illumination light is preferably larger than the incident angle of the first reconstruction illumination light. Incidentally, the incident angle of the second reconstruction illumination light is usually less than 90°.

Moreover, in the above case, the second observation angle is preferably larger than the first observation angle. Note that the second viewing angle is typically less than 90°.

Here, the incident angle of the reconstruction illumination light is the angle between the light source of the reconstruction illumination light and the normal direction of the surface of the volume hologram laminate. For example, in FIGS. 3A and 3B, the incident angles θ1 and θ3 of the reconstruction illumination light L are angles with respect to the normal direction d of the surface of the volume hologram laminate 10 .

Also, the observation angle is the angle with respect to the normal direction of the surface of the volume hologram laminate. For example, in FIG. 3B, the observation angle θ4 is the angle of the observation direction D2 with respect to the normal direction d of the surface of the volume hologram laminate 10 . In addition, in FIG. 3A, the observation angle is 0°.

Further, when the incident angle and first observation angle of the first reconstruction illumination light are gradually changed to the second reconstruction illumination light and second observation angle, the reproduction wavelength of the volume hologram layer preferably changes gradually. Thus, when the incident angle and first viewing angle of the first reconstruction illumination light are gradually changed to the second viewing angle and incident angle of the second reconstruction illumination light, the color of the reproduced image from the volume hologram layer can be continuously changed, and excellent design can be achieved.

In the above case, for example, when the incident angle of the second reconstruction illumination light is larger than the incident angle of the first reconstruction illumination light and the second observation angle is larger than the first observation angle, it is preferable that the reproduction wavelength of the volume hologram layer gradually becomes shorter when the incident angle of the first reconstruction illumination light and the first observation angle are gradually changed to the incident angles of the second reconstruction illumination light and the second observation angle.

The reproduction illumination light is not particularly limited as long as it includes the reproduction wavelength of the volume hologram layer. For example, white light or the like can be used. White light sources include, for example, white fluorescent lamps, white LEDs, and sunlight.

In the present disclosure, as a method for changing the reproduction wavelength of the volume hologram layer according to the incident angle and observation angle of the reproduction illumination light and changing the color of the reproduced image from the volume hologram layer, a method is used in which interference fringes are recorded in the volume hologram layer during the formation of the volume hologram layer, then a resin layer is placed in contact with the volume hologram layer, and a low-molecular-weight substance such as an uncured photopolymerizable compound contained in the volume hologram layer is transferred to the resin layer, thereby shifting the reproduction wavelength of the volume hologram layer to a shorter wavelength side with respect to the recording wavelength. In this case, by controlling the shift amount of the reproduction wavelength of the volume hologram layer to the short wavelength side, the reproduction wavelength of the volume hologram layer can be changed according to the incident angle and observation angle of the reproduction illumination light, and the color of the reproduced image from the volume hologram layer can be changed.

As a method of controlling the amount of shift of the reproduction wavelength of the volume hologram layer to the short wavelength side, for example, a method of controlling the amount of migration of a low-molecular-weight substance contained in the volume hologram layer to the resin layer can be mentioned. If the amount of migration of the low-molecular substance is small, the shrinkage of the volume hologram layer is small and the amount of shift in the reproduction wavelength is small.

Examples of methods for controlling the amount of low-molecular-weight substances that migrate to the resin layer in the volume hologram layer include a method of adjusting the composition of the resin layer, the thickness of the resin layer, and the heating conditions when heating the volume hologram layer and the resin layer in contact with each other. For example, if the transparent resin contained in the resin layer and the low-molecular-weight substance contained in the volume hologram layer have good compatibility, the migration amount of the low-molecular-weight substance tends to increase and the reproduction wavelength shift amount tends to increase. Further, for example, it is considered that there is a permissible amount of migration of low-molecular-weight substances from the volume hologram layer to the resin layer, so if the resin layer is thick, the amount of migration of low-molecular-weight substances tends to increase and the amount of shift in the reproduction wavelength tends to increase. Further, for example, the migration amount of the low-molecular-weight substance is the product of the low-molecular-weight substance migration rate (diffusion rate, heating temperature) and the migration time (diffusion time, heating time). Therefore, the volume hologram layer and the resin layer can be adjusted by controlling the heating temperature and the heating time when heating in a state of being in contact with each other. Specifically, when the heating temperature is high, the amount of migration of low-molecular-weight substances tends to increase, and the amount of shift in the reproduction wavelength tends to increase. When the heating time is long, the amount of migration of low-molecular-weight substances tends to increase, and the amount of shift in the reproduction wavelength tends to increase.

2. Volume Hologram Laminated Part The volume hologram laminated part in the present embodiment comprises a volume hologram layer containing a polymer of a photopolymerizable compound, in which interference fringes are recorded, and a resin layer containing a transparent resin, which are arranged so as to be in contact with each other.

(1) Resin Layer The resin layer in this embodiment contains a transparent resin and is arranged in contact with the volume hologram layer.

(a) Material of resin layer (i) Transparent resin The transparent resin used in the present disclosure is not particularly limited as long as it has transparency. Specific examples of transparent resins include acrylic resins, styrene resins, polyester resins, urethane resins, polyvinyl resins, alkyd resins, petroleum resins, ketone resins, various synthetic resins such as epoxy resins, melamine resins, fluorine resins, silicone resins, cellulose derivatives, rubber resins, or plastic resins such as mixtures and copolymers of two or more thereof; melamine resins, phenol resins, urea resins, epoxy resins, unsaturated polyester resins, diallyl phthalate. Thermosetting resins such as system resins, urethane-based resins, and aminoalkyd-based resins; curable resins such as ionizing radiation-curable resins that are cured by irradiation with ultraviolet rays or electron beams, such as acrylate-based resins, urethane acrylate-based resins, ester acrylate-based resins, and epoxy acrylate-based resins; The transparent resin may be used singly or in combination of two or more.

(ii) Low-molecular-weight substance The resin layer in this embodiment preferably contains the same low-molecular-weight substance as the low-molecular-weight substance used in the volume hologram layer, or a polymer of the low-molecular-weight substance. As described above, in the manufacturing process of the volume hologram layer, after interference fringes are recorded in the volume hologram layer, when the volume hologram layer and the resin layer are heated while they are in contact with each other, uncured photopolymerizable compounds and other low-molecular-weight substances contained in the volume hologram layer migrate to the resin layer, so that the reproduction wavelength of the volume hologram layer can be shifted to the shorter wavelength side with respect to the recording wavelength. Further, in the process of manufacturing the volume hologram laminate, after the volume hologram layer and the resin layer are heated in contact with each other, the uncured photopolymerizable compound contained in the volume hologram layer and the resin layer is polymerized. Therefore, the resin layer contains the same low-molecular-weight substance as the low-molecular-weight substance used in the volume hologram layer, or a polymer of the low-molecular-weight substance.

Low-molecular-weight substances include, for example, photopolymerizable compounds contained in the volume hologram layer. Furthermore, the low-molecular-weight substance also includes a photoinitiator system contained in the volume hologram layer. That is, the resin layer preferably contains the same photopolymerizable compound as the photopolymerizable compound contained in the volume hologram layer, or a polymer of the photopolymerizable compound. Further, the resin layer may contain the same photopolymerizable compound and photopolymerization initiator system as the photopolymerizable compound and photopolymerization initiator system contained in the volume hologram layer, respectively, or a polymer of the photopolymerizable compound and a photopolymerization initiator.

The photopolymerizable compound and the photopolymerization initiator system will be described later in the volume hologram layer section, so descriptions thereof will be omitted here.

(iii) Arbitrary compound The resin layer in this embodiment may contain an arbitrary compound in addition to the transparent resin and the low-molecular-weight substance. The optional compound is not particularly limited, and can be appropriately selected and used according to the application of the volume hologram laminate of the present embodiment, which can impart a desired function to the resin layer. Examples of optional compounds include antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, plasticizers, lubricants, antistatic agents, flame retardants, fillers, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of antioxidants include phenol-based, sulfur-based, and phosphorus-based antioxidants. Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, salicylate-based, cyanoacrylate-based, formamidine-based, and oxanilide-based. Examples of light stabilizers include hindered amine-based and nickel complex-based stabilizers. Examples of heat stabilizers include hindered phenol-based, sulfur-based, hydrazine-based, and the like. The plasticizer is appropriately selected according to the type of the transparent resin, and examples thereof include phthalate esters, phosphate esters, fatty acid esters, aliphatic dibasic acid esters, oxybenzoate esters, epoxies, and polyesters. Examples of lubricants include fatty acid ester-based, fatty acid-based, metal soap-based, fatty acid amide-based, higher alcohol-based, and paraffin-based lubricants. Examples of antistatic agents include cationic, anionic, nonionic, amphoteric and the like. Examples of flame retardants include bromine-based, phosphorus-based, chlorine-based, nitrogen-based, aluminum-based, antimony-based, magnesium-based, boron-based, and zirconium-based flame retardants. Examples of fillers include calcium carbonate, talc, roselite, kaolin and the like.

(b) Other points of the resin layer The thickness of the resin layer is not particularly limited as long as the reproduction wavelength of the volume hologram layer can be shifted to the short wavelength side with respect to the recording wavelength, and is appropriately adjusted according to the type of the transparent resin. As described above, by adjusting the thickness of the resin layer, the shift amount of the reproduction wavelength of the volume hologram layer can be adjusted. Therefore, it is preferable to adjust the thickness of the resin layer so that the reproduced image from the volume hologram layer can have a desired color. Specifically, the thickness of the resin layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 3 μm or less.

In addition, in the production of the volume hologram laminate of this embodiment, since the resin layer is placed in contact with the volume hologram layer after the interference fringes are recorded in the volume hologram layer, no interference fringes are recorded in the resin layer.

Here, the fact that no interference fringes are recorded in the resin layer can be confirmed by observing a section obtained by cutting the resin layer in the thickness direction with a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

(2) Volume Hologram Layer The volume hologram layer in this embodiment contains a polymer of a photopolymerizable compound, has interference fringes recorded therein, and is arranged in contact with the resin layer.

Interference fringes are recorded in the volume hologram layer, and light is diffracted by the interference fringes to reproduce an image. In the present disclosure, the volume hologram layer is usually a reflective volume hologram layer, a so-called Lippmann hologram. A reflective volume hologram layer is a volume hologram layer from which an image can be reproduced by irradiating the surface of the volume hologram layer on the viewer side with reproduction illumination light.

An image reproduced by the interference fringes recorded in the volume hologram layer can be appropriately designed.

(a) Material for volume hologram layer (i) Polymerization of photopolymerizable compound The photopolymerizable compound used in the present disclosure is not particularly limited as long as it can cause a polymerization reaction to proceed when irradiated with a predetermined light and can record interference fringes on the volume hologram layer, but usually at least one of a radically polymerizable compound and a cationically polymerizable compound is used. Moreover, you may use together a radically polymerizable compound and a cationically polymerizable compound.

Furthermore, when a radically polymerizable compound is used as the photopolymerizable compound, a radical photopolymerization initiator system is also used to initiate the polymerization reaction of the radically polymerizable compound. On the other hand, when a cationic polymerizable compound is used as the photopolymerizable compound, a cationic photopolymerization initiator system is also used for the same reason. Therefore, when a radically polymerizable compound and a cationic polymerizable compound are used as the photopolymerizable compound, a radical photopolymerization initiator system and a cationic photopolymerization initiator system are used.

Since the volume hologram layer already has interference fringes recorded therein, it contains a polymer of a photopolymerizable compound.

Hereinafter, the radically polymerizable compound, the cationic polymerizable compound, the radical photopolymerization initiator system, and the cationic photopolymerization initiator system used in the present disclosure will be described in order.

(i-1) Cationic polymerizable compound The cationic polymerizable compound used in the present disclosure is a compound that undergoes cationic polymerization with a Bronsted acid or a Lewis acid generated by decomposition of a photocationic polymerization initiator system described later when irradiated with an energy ray.

Here, the formation of the volume hologram layer is carried out, for example, by irradiating a laser beam to polymerize a radically polymerizable compound to be described later, recording interference fringes, and then irradiating the entire surface with an energy beam to polymerize an uncured substance such as a cationic polymerizable compound. At this time, a laser beam or the like for recording the interference fringes and an energy beam irradiated to the entire surface normally have different wavelengths. Therefore, the cationic polymerizable compound is preferably a compound that does not polymerize at the wavelength of the light source used when recording the interference fringes.

Moreover, the cationically polymerizable compound is preferably liquid at room temperature because the polymerization of the radically polymerizable compound is preferably carried out in a composition having a relatively low viscosity. In addition, normal temperature means 20±15 degreeC.

Examples of such cationic polymerizable compounds include, for example, "Chemtec.Oct." V. JV Crivello, pp. 624 (1980), JP-A-62-149784, Journal of the Adhesion Society of Japan [vol. 5, pp. 179-187 (1990)].

Specifically, diglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, 1,4-bis(2,3-epoxypropoxyperfluoroisopropyl)cyclohexane, sorbitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcinol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, phenylglycidyl ether, para-tert-butylphenylglycidyl ether, and diglycidyl adipate. esters, diglycidyl orthophthalate, dibromophenyl glycidyl ether, dibromoneopentyl glycol diglycidyl ether, 1,2,7,8-diepoxyoctane, 1,6-dimethylolperfluorohexanediglycidyl ether, 4,4'-bis(2,3-epoxypropoxyperfluoroisopropyl)diphenyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexyloxirane, 1,2,5,6-diepoxy-4,7-methanoperhydroindene, 2-(3,4-epoxycyclohexyl)-3',4'-epoxy-1,3-dioxane-5-spirocyclohexane, 1,2-ethylenedioxy-bis(3,4-epoxycyclohexylmethane), 4',5'-epoxy-2'-methylcyclohexylmethyl-4,5-epoxy-2-methylcyclohexanecarboxylate, ethylene glycol-bis(3,4-epoxycyclo hexane carboxylate), bis-(3,4-epoxycyclohexylmethyl)adipate, di-2,3-epoxycyclopentyl ether, vinyl-2-chloroethyl ether, vinyl-n-butyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, trimethylolethane trivinyl ether, vinyl glycidyl ether, and compounds represented by the following formulas.

In addition, in the above formula, n represents an integer of 1 or more and 5 or less. Also, m is 3 or 4, and R represents an ethyl group or a hydroxymethyl group.

The cationic polymerizable compounds may be used singly or in combination of two or more.

(i-2) Radically polymerizable compound The radically polymerizable compound used in the present disclosure is not particularly limited as long as it is a compound that polymerizes by the action of an active radical generated from a photoradical polymerization initiator system described later, for example, by laser irradiation or the like when forming a volume hologram layer, but preferably has at least one ethylenically unsaturated double bond in the molecule.

Here, the volume hologram layer records interference fringes by polymerizing a radically polymerizable compound with, for example, laser light or light with excellent coherence. Therefore, the radically polymerizable compound and the cationic polymerizable compound are usually selected and used with different refractive indices. The magnitude relationship between the refractive indices of the radically polymerizable compound and the cationically polymerizable compound is not particularly limited, but from the viewpoint of material selectivity, it is preferable that the average refractive index of the radically polymerizable compound is larger than the average refractive index of the cationically polymerizable compound, specifically, the average refractive index is preferably 0.02 or more. If the difference in average refractive index between the radically polymerizable compound and the cationically polymerizable compound is too small, the refractive index modulation will be insufficient, possibly making it difficult to obtain a high-definition image.

The average refractive index is the average value of the refractive indices measured for the polymer obtained after polymerizing the cationically polymerizable compound or the radically polymerizable compound. Moreover, a refractive index means the value measured by the Abbe refractometer.

Radical polymerizable compounds include, for example, methyl methacrylate, hydroxyethyl methacrylate, lauryl acrylate, N-acryloylmorpholine, 2-ethylhexylcarbitol acrylate, isobornyl acrylate, methoxypropylene glycol acrylate, ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,4-cyclohexanediol diacrylate, 1,6-hexanediol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, trimethylolpropane tri(acryloyloxypropyl)ether, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri(acrylate) royloxyethyl) isocyanurate, polyester acrylate oligomer, acrylamide, methacrylamide, methylenebisacrylamide, styrene, 2-bromostyrene, 2-phenoxyethyl acrylate, phenol ethoxylate monoacrylate, 2-(p-chlorophenoxy)ethyl acrylate, p-chlorophenyl acrylate, phenyl acrylate, 2-phenylethyl acrylate, 2,3-naphthalenedicarboxylic acid (acryloxyethyl) monoester, methylphenoxyethyl acrylate, nonylphenoxyethyl acrylate, β-acryloxyethyl hydrogen phthalate , phenoxypolyethylene glycol acrylate, benzyl acrylate, 2,4,6-tribromophenyl acrylate, 2,3-dibromopropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-naphthyl acrylate, 2-(1-naphthyloxy)ethyl acrylate, o-biphenyl acrylate, dicyclopentanyl acrylate, dibromoneeopentyl glycol diacrylate, 1,3-bis[2-acryloxy-3-(2,4,6-tribromophenoxy)propoxy]benzene, N-vinyl Carbazole, 2-(9-carbazolyl)ethyl acrylate, diphenic acid (2-methacryloxyethyl) monoester, diphenic acid (2-acryloxyethyl) (3-acryloxypropyl-2-hydroxy) diester, 2,3-naphthalenedicarboxylic acid (2-acryloxyethyl) (3-acryloxypropyl-2-hydroxy) diester, 4,5-phenanthenedicarboxylic acid (2-acryloxyethyl) (3-acryloxypropyl- 2-hydroxy)diester, bis(4-acryloxydiethoxyphenyl)methane, bis(4-acryloxyethoxy-3,5-dibromophenyl)methane, 2,2-bis(4-acryloxyethoxyphenyl)propane, 2,2-bis(4-acryloxydiethoxyphenyl)propane, 2,2-bis(4-acryloxyethoxy-3,5-dibromophenyl)propane, 9,9-bis(4-acryloxy) 9,9-bis(4-acryloxytriethoxyphenyl)fluorene, 9,9-bis(4-acryloxydipropoxyphenyl)fluorene, 9,9-bis(4-acryloxyethoxy-3-methylphenyl)fluorene, 9,9-bis(4-acryloxyethoxy-3-ethylphenyl)fluorene, 9,9-bis(4-acryloxyethoxy-3 ,5-dimethyl)fluorene, diethylenedithioglycol acrylate, triphenylmethylthioacrylate, 2-(tricyclo(5,2,102,6)dibromodecylthio)ethyl acrylate, S-(1-naphthylmethyl)thioacrylate, bis(4-acryloxyethoxyphenyl)sulfone, bis(4-acryloxydiethoxyphenyl)sulfone, bis(4-acryloxypropoxyphenyl)sulfone, bis(4-acryloxyethoxy-3,5-di bromophenyl)sulfone, and compounds where "acrylate" is changed to "methacrylate" and "acryloxy" is changed to "methacryloxy" in the above. Furthermore, sulfur-containing acrylic compounds disclosed in JP-A-61-72748 can also be used. Ethylthio)diphenyl ketone, compounds obtained by changing "acryloyl" in the above to "methacryloyl", and compounds containing at least two S atoms in the molecule as disclosed in JP-A-2-247205 and JP-A-2-261808, and ethylenically unsaturated double bond-containing compounds. The radically polymerizable compound may be used singly or in combination of two or more.

(i-3) Radical Photopolymerization Initiator System The photoradical polymerization initiator system used in the present disclosure is not particularly limited as long as it is an initiator system capable of generating active radicals and polymerizing the radically polymerizable compound when the volume hologram layer is formed. Examples of such radical photopolymerization initiator systems include, for example, U.S. Pat. 715, JP-A-4-239505 and "PROCEEDINGS OF CONFERENCE ON RADIATION CURRING ASIA" (pp. 461-477, 1988).

(i-4) Photocationic polymerization initiator system The photocationic polymerization initiator system used in the present disclosure is not particularly limited as long as it generates Bronsted acid or Lewis acid by irradiation with energy rays and polymerizes the above cationic polymerizable compound. Among them, it is preferable to use a low-photosensitivity material that does not react to laser light that polymerizes the radically polymerizable compound, light that has excellent coherence, or the like, and that is sensitive to energy rays that are subsequently irradiated to the entire surface. As a result, when the radically polymerizable compound is polymerized, the cationic polymerizable compound can remain almost unreacted, and a large refractive index modulation can be obtained in the volume hologram layer.

Here, the photocationic polymerization initiator having low photosensitivity to laser light and light with excellent coherence means that the maximum DSC value due to photopolymerization initiated by the photocationic polymerization initiator system is 500 mW or less (including 0 mW) per 1 mg of the measurement sample when thermal analysis is performed under the following conditions.

<Measurement conditions>
Measuring apparatus: A differential scanning calorimeter DSC220 and a light source UV-1 are used in an SSC5200H thermal analysis system manufactured by Seiko Denshi Kogyo Co., Ltd.
Measurement sample: Prepared by dissolving 3% by mass of a subject photocationic polymerization initiator system in Union Carbide's UVR-6110 (cationically polymerizable compound). The organic solvent may be evaporated after adding and dissolving the organic solvent.
Irradiation light: 200 mJ/cm ² of light adjusted to the same extent as laser light or light with excellent coherence using an interference filter (half width of about 10 nm) is applied.

Such photocationic polymerization initiator systems are described, for example, in "UV Curing: Science and Technology", pp. 23-76, edited by S. Peter Pappas, A Technology Marketing Publication and "Comments Inorganic." Chemistry (Comments Inorg. Chem.), B. Klingert, M. Riediker and A. Roloff, Vol. 7, No. 3, pp. 109-138 (1988). The photocationic polymerization initiator system may be used singly or in combination of two or more.

Among the above, preferred diaryliodonium salts include iodonium tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, trifluoromethanesulfonate, 9,10-dimethoxyanthracene sulfonate, and the like shown in the photoradical polymerization initiator system described above. Preferred triarylsulfonium salts include sulfonium tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate and hexafluoroantimonate, trifluoromethanesulfonate, 9,10-dimethoxyanthracene-2-sulfonate and the like, such as triphenylsulfonium, 4-tert-butyltriphenylsulfonium, tris(4-methylphenyl)sulfonium, tris(4-methoxyphenyl)sulfonium, and 4-thiophenyltriphenylsulfonium.

As the radical photopolymerization initiator system or the cationic photopolymerization initiator system, an initiator system having the properties of the radical photopolymerization initiator system and the properties of the cationic photopolymerization initiator system may be used. Examples of such initiator systems include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, iron arene complexes, and the like. Specifically, iodonium chlorides such as diphenyliodonium, ditolyliodonium, bis(pt-butylphenyl)iodonium and bis(p-chlorophenyl)iodonium, iodonium salts such as bromides, fluoroborates, hexafluorophosphate salts, and hexafluoroantimonate salts; 2,4,6-substituted-1,3,5-triazine compounds such as 2,4,6-tris(trichloromethyl)-1,3,5-triazine, 2-phenyl-4,6-bis(trichloromethyl)-1,3,5-triazine, and 2-methyl-4,6-bis(trichloromethyl)-1,3,5-triazine.

(ii) Arbitrary compound The volume hologram layer in this embodiment may contain an arbitrary compound other than the polymer of the photopolymerizable compound described above. The arbitrary compound is not particularly limited as long as it can impart a desired function to the volume hologram layer according to the application of the volume hologram laminate of this embodiment. Examples of optional compounds include sensitizing dyes, fine particles, thermal polymerization inhibitors, silane coupling agents, plasticizers, colorants, and binder resins.

Binder resins include, for example, polymethacrylic acid ester or its partial hydrolyzate, polyvinyl acetate or its hydrolyzate, polyvinyl alcohol or its partial acetalized product, triacetyl cellulose, polyisoprene, polybutadiene, polychloroprene, silicone rubber, polystyrene, polyvinyl butyral, polyvinyl chloride, polyarylate, chlorinated polyethylene, chlorinated polypropylene, poly-N-vinylcarbazole or its derivatives, poly-N-vinylpyrrolidone or its derivatives, copolymerization of styrene and maleic anhydride. or its half-esters, and the like. A copolymer obtained by polymerizing at least one monomer selected from the group consisting of copolymerizable monomers such as acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylamide, acrylonitrile, ethylene, propylene, vinyl chloride, and vinyl acetate can also be used. The binder resin may be used alone or in combination of two or more.

Moreover, an oligomer-type curable resin can also be used as the binder resin. Examples of such resins include epoxy compounds produced by a condensation reaction of various phenolic compounds such as bisphenol A, bisphenol S, novolak, o-cresol novolac, and p-alkylphenol novolak with epichlorohydrin.

Furthermore, an organic-inorganic hybrid polymer utilizing a sol-gel reaction can also be used as the binder resin. Examples of such a resin include a copolymer of an organometallic compound having a polymerizable group represented by the following general formula (1) and a vinyl monomer.
R' _m M (OR'') _n (1)
(Here, M is a metal such as Si, Ti, Zr, Zn, In, Sn, Al, Se, R′ is a vinyl group or (meth)acryloyl group having 1 to 10 carbon atoms, R″ represents an alkyl group having 1 to 10 carbon atoms, and m+n is the valence of the metal M).

Examples of organometallic compounds when the metal M is Si include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltributoxysilane, vinyltriallyloxysilane, vinyltetraethoxysilane, vinyltetramethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and the like.

Examples of vinyl monomers include acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters.

Here, in the volume hologram layer, interference fringes are recorded as refractive index modulation or transmittance modulation. Therefore, it is preferable that the refractive index difference between the binder resin and the photopolymerizable compound is large. An organometallic compound represented by the following general formula (2) can also be added to the volume hologram layer in order to increase the refractive index difference between the binder resin and the photopolymerizable compound.
M'(OR''') _k (2)
(Here, M′ is a metal such as Ti, Zr, Zn, In, Sn, Al, Se, R′″ represents an alkyl group having 1 to 10 carbon atoms, and k is the valence of the metal M).

When the compound represented by the above formula (2) is added, it forms a network structure with the binder resin through a sol-gel reaction in the presence of water and an acid catalyst, so that not only the refractive index of the binder resin is increased, but also the toughness and heat resistance of the layer can be improved. Therefore, in order to increase the refractive index difference with the photopolymerizable compound, the metal M' preferably has a high refractive index.

The sensitizing dye is selected in consideration of the laser light wavelength used when recording interference fringes, and is not particularly limited. Examples of sensitizing dyes include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, coumarin dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes, pyrylium dyes, cyclopentanone dyes, and cyclohexanone dyes.

Examples of cyanine dyes and merocyanine dyes include 3,3'-dicarboxyethyl-2,2'-thiocyanine bromide, 1-carboxymethyl-1'-carboxyethyl-2,2'-quinocyanine bromide, 1,3'-diethyl-2,2'-quinothiacyanine iodide, 3-ethyl-5-[(3-ethyl-2(3H)-benzothiazolylidene)ethylidene]-2-thioxo-4-oxazoly gin and the like. Examples of coumarin dyes and ketocoumarin dyes include 3-(2'-benzimidazole) 7-N,N-diethylaminocoumarin, 3,3'-carbonylbis(7-diethylaminocoumarin), 3,3'-carbonylbiscoumarin, 3,3'-carbonylbis(5,7-dimethoxycoumarin), and 3,3'-carbonylbis(7-acetoxycoumarin).

When high transparency is required for optical elements, the sensitizing dye that is active in visible light is preferably one that becomes colorless by being decomposed by heating or ultraviolet irradiation in a post-process after interference fringe recording. As such a sensitizing dye, the above-described cyanine dyes are preferably used.

(b) Other Points of Volume Hologram Layer It is preferable that the glass transition temperature of the volume hologram layer is, for example, 100° C. or higher. As a result, even when heat is applied to the volume hologram layer, the volume hologram layer can be stabilized, and the volume hologram layer can be transferred by, for example, a thermal transfer method.

Here, the glass transition temperature can be measured using a differential thermal analyzer (DSC) or the like.

The thickness of the volume hologram layer is not particularly limited as long as it is thick enough to record the desired interference fringes.

(2) Arrangement of volume hologram layer and resin layer The volume hologram layer and resin layer in this embodiment have the above-mentioned volume hologram layer and resin layer in random order.

3. Substrate The substrate used in this embodiment is a member that supports the above-described volume hologram laminate.

The substrate is not particularly limited as long as it can support the volume hologram laminate, and can be appropriately selected and used according to the application of the volume hologram laminate of this embodiment.

Specific examples of the substrate include a polyethylene film, a polypropylene film, a polyethylene fluoride film, a polyvinylidene fluoride film, a polyvinyl chloride film, a polyvinylidene chloride film, an ethylene-vinyl alcohol copolymer film, a polyvinyl alcohol film, a polymethyl methacrylate film, a polyethersulfone film, a polyetheretherketone film, a polyamide film, a tetrafluoroethylene-perfluoroalkylvinylether copolymer film, a polyester film such as a polyethylene terephthalate film, and a transparent resin film such as a polyimide film.

Also, the thickness of the base material is appropriately selected according to the application, type, etc. of the volume hologram laminate of the present embodiment, and is, for example, 2 μm or more and 200 μm or less, preferably 10 μm or more and 50 μm or less.

The base material may be surface-treated for the purpose of enhancing adhesion to the resin layer or the like. Examples of surface treatment include corona treatment, ozone treatment, plasma treatment, ionizing radiation treatment, dichromic acid treatment, anchor or primer treatment, and the like. Examples of the primer agent include various primer agents such as urethane-based, acrylic, ethylene-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer-based primers.

4. Arbitrary Configuration The volume hologram laminate of this embodiment may have any configuration other than the above-described volume hologram laminate and base material, if necessary. The arbitrary configuration is not particularly limited, and a configuration having a desired function can be used according to the application of the volume hologram laminate of this embodiment. Optional structures include, for example, a hard coat layer, an antistatic layer, a printing layer, an ink-receiving layer, and a release layer.

5. Volume hologram laminate manufacturing method As a method for manufacturing the volume hologram laminate of the present embodiment, for example, a manufacturing method can be used that includes, in order, a volume hologram layer forming step of forming a volume hologram layer containing a photopolymerizable compound and a photopolymerization initiator system, a photographing step of recording interference fringes in the volume hologram layer, a lamination step of placing a resin layer in contact with the volume hologram layer in which the interference fringes are recorded, and a heating step of heating the volume hologram layer and the resin layer in contact with each other. In addition, the method for producing a volume hologram laminate of this embodiment may further include a post-treatment step of polymerizing the uncured photopolymerizable compound after the heating step.

4A to 4D are process diagrams showing an example of the method for manufacturing the volume hologram laminate of this embodiment. First, as shown in FIG. 4A, a volume hologram lamination step is performed to form a volume hologram layer 2a containing a photopolymerizable compound and a photopolymerization initiator system on one surface of the first substrate 1a. Next, as shown in FIG. 4B, a photographing step is performed to record interference fringes in the volume hologram layer 2a. Next, as shown in FIG. 4(c), using a resin film 11 in which a resin layer 2b is arranged on one side of a second substrate 1b, a lamination step is performed in which the resin film 11 is laminated on the volume hologram layer 2a so that the volume hologram layer 2a on which the interference fringes are recorded and the resin layer 2b are in contact with each other. Next, a heating step is performed in which the volume hologram layer 2a on which interference fringes are recorded and the resin layer 2b are in contact with each other. Subsequently, a post-treatment step is performed to polymerize the uncured photopolymerizable compound contained in the volume hologram layer 2a and the resin layer 2b. As a result, as shown in FIG. 4(d), a laminate having the first substrate 1a, the volume hologram laminate 2 having the volume hologram layer 2a and the resin layer 2b, and the second substrate 1b is obtained. After that, although not shown, the volume hologram laminate can be obtained by peeling off the first base material 1a or the second base material 1b.

In this embodiment, the photographing step, the lamination step, and the heating step are performed in order, and in the heating step, the volume hologram layer and the resin layer are heated while they are in contact with each other. By transferring the low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer to the resin layer, the volume hologram layer shrinks and the interval between the interference fringes narrows. At this time, by controlling the shift amount of the reproduction wavelength, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and a volume hologram laminate in which the color of the reproduced image from the volume hologram layer changes can be obtained.

The method for controlling the shift amount of the reproduction wavelength of the volume hologram layer is as described above.

Each step of the method for manufacturing the volume hologram laminate of this embodiment will be described below.

(1) Volume Hologram Layer Forming Step Examples of the method of forming the volume hologram layer include a method of applying a volume hologram layer composition containing a photopolymerizable compound, a photopolymerization initiator system, and a solvent to one surface of the first substrate.

(2) Imaging Process Interference fringes produced by light interference are recorded in the volume hologram layer as fringes with different refractive indices by polymerizing a photopolymerizable compound. The method of recording interference fringes in the volume hologram layer is not particularly limited, and examples include a method in which reference light is incident from the first substrate side and object light is incident from the volume hologram layer side, and these beams are caused to interfere within the volume hologram layer, and a method in which incident light and reflected light reflected by the hologram master are caused to interfere within the volume hologram layer by placing a hologram master plate on the surface on the side of the volume hologram layer and entering light from the first substrate side. In the method using a hologram master plate, interference fringes can be easily recorded.

When a single photopolymerizable compound is used as the photopolymerizable compound contained in the volume hologram layer, interference fringes are recorded by polymerizing the photopolymerizable compound. On the other hand, when two or more types of photopolymerizable compounds are used as the photopolymerizable compounds contained in the volume hologram layer, interference fringes may be recorded by polymerizing at least one type of photopolymerizable compound. When the above-described radically polymerizable compound and cationic polymerizable compound are used as the photopolymerizable compound, interference fringes are usually recorded by polymerizing the radically polymerizable compound.

(3) Lamination process As a method of arranging the resin layer in contact with the volume hologram layer, for example, a method of using a resin film in which a resin layer is arranged on one side of the second base material and arranging the resin film in contact with the volume hologram layer can be mentioned. The method for producing the resin film is appropriately selected according to the type of the transparent resin or the like used for the resin layer. For example, a method of forming a resin layer by applying a resin composition containing a melt of a transparent resin or a transparent resin and a solvent to one surface of the second substrate.

Through the lamination step, a laminate having the first substrate, the volume hologram layer, the resin layer, and the second substrate in this order is obtained. When the second base material is peeled off after the heating step, a volume hologram laminate having a base material, a volume hologram layer and a resin layer in this order can be obtained. On the other hand, when the first substrate is peeled off after the heating step, a volume hologram laminate having a volume hologram layer, a resin layer and a substrate in this order can be obtained.

(4) Heating step By heating the volume hologram layer and the resin layer in contact with each other, low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer can migrate to the resin layer according to the principle of equilibrium transfer. At this time, by controlling the heating temperature and heating time, the migration amount of the low-molecular substance can be adjusted.

(5) Post-treatment step In the heating step, low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer migrate to the resin layer, so that the volume hologram layer and the resin layer contain uncured photopolymerizable compounds. Therefore, in a post-treatment process, the uncured photopolymerizable compound contained in the volume hologram layer and the resin layer can be polymerized and fixed.

The method for polymerizing the uncured photopolymerizable compound is appropriately selected according to the type of the photopolymerizable compound, and includes a method of irradiating energy rays. Energy rays include, for example, ultraviolet rays, electron rays, visible rays, and the like.

II. Second Embodiment A second embodiment of the volume hologram laminate of the present disclosure includes a substrate and a volume hologram laminate disposed on one surface of the substrate, wherein the volume hologram laminate contains a polymer of a photopolymerizable compound and includes a volume hologram layer in which interference fringes are recorded, and a resin layer that is arranged in a pattern in contact with the volume hologram layer and contains a transparent resin, in random order.

FIG. 5 is a schematic diagram showing an example of the volume hologram laminate of this embodiment. As illustrated in FIG. 5 , the volume hologram laminate 10 has a substrate 1 and a volume hologram laminate 2 arranged on one surface of the substrate 1 . The volume hologram laminate section 2 includes a volume hologram layer 2a containing a polymer of a photopolymerizable compound and having interference fringes recorded thereon, and a resin layer 2b arranged in a pattern in contact with the volume hologram layer 2a and containing a transparent resin, in random order.

5, the volume hologram laminate 2 has the resin layer 2b and the volume hologram layer 2a in order from the substrate 1 side, but as shown in FIG. 6, the volume hologram laminate 2 may have the volume hologram layer 2a and the resin layer 2b in order from the substrate 1 side.

Here, as described in the above section of the first embodiment, in the production of the volume hologram laminate, for example, after interference fringes are recorded in the volume hologram layer, a resin layer is arranged in contact with the volume hologram layer, and the volume hologram layer shrinks by transferring low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer to the resin layer, thereby narrowing the distance between the interference fringes.

Therefore, the reproduction wavelength of the volume hologram layer 2a in the resin layer forming area A1 where the resin layer 2b is arranged can be shifted to the shorter wavelength side with respect to the reproduction wavelength of the volume hologram layer 2a in the resin layer non-forming area A2 where the resin layer 2b is not arranged.

Specifically, when the recording wavelength during interference fringe recording is in the green wavelength range, the color of the image reproduced from the volume hologram layer 2a can be green in the resin layer non-formation region A2 where the resin layer 2b is not arranged, and the color of the reproduction image from the volume hologram layer 2a can be blue in the resin layer formation region A1 where the resin layer 2b is arranged.

Generally, in a volume hologram, when monochromatic laser light is used to record interference fringes, the reproduced image is monochromatic. On the other hand, in the volume hologram laminate of this embodiment, the color of the reproduced image from the volume hologram layer can be made different between the resin layer forming region where the resin layer is arranged and the resin layer non-forming region where the resin layer is not arranged. That is, a volume hologram laminate having two different response wavelengths is obtained, and a multicolor reproduced image can be obtained. Therefore, the anti-counterfeiting effect can be enhanced. Furthermore, a volume hologram laminate having excellent design properties can be obtained.

As in the first embodiment, in the volume hologram laminate of the present embodiment, the volume hologram layer and the resin layer are in contact with each other. For example, after recording interference fringes in the volume hologram layer, the volume hologram laminate can be produced by arranging the resin layer in a pattern so as to be in contact with the volume hologram layer and transferring low-molecular substances such as uncured photopolymerizable compounds contained in the volume hologram layer to the resin layer. Therefore, even though the interference fringes are recorded using a monochromatic laser beam, a volume hologram laminate can be obtained in which the color of the reproduced image from the volume hologram layer differs between the resin layer formed region where the resin layer is arranged and the resin layer non-formed region where the resin layer is not arranged. Furthermore, it is possible to obtain a volume hologram laminate with a high anti-counterfeiting effect by a simple method. Therefore, the color variations of the volume hologram laminate can be increased without introducing new equipment.

Further, in the volume hologram laminate of the present embodiment, in the resin layer forming region where the resin layer is arranged, it is possible to change the reproduction wavelength of the volume hologram layer according to the incident angle and observation angle of the reproduction illumination light, thereby changing the color of the reproduced image from the volume hologram layer.

FIGS. 7A and 7B are schematic diagrams for explaining the method of reproducing the volume hologram laminate of this embodiment.

First, as shown in FIG. 7A, an observer observes the volume hologram laminate 10 from an observation direction D1 that is 0° with respect to the normal direction d of the surface of the volume hologram laminate 10 while the reconstruction illumination light L having a predetermined incident angle θ1 with respect to the normal direction d of the surface of the volume hologram laminate 10 is irradiated. At this time, for example, when the recording wavelength during interference fringe recording is in the green wavelength range, the incident angle θ1 of the reproduction illumination light L is substantially the same as the incident angle of the reference light during interference fringe recording, and the observation angle (the angle in the observation direction D1) is substantially the same as the incident angle of the object light during interference fringe recording, the observer can observe a green reproduced image similar to the color of the recording wavelength during interference fringe recording in both the resin layer formed area A1 and the resin layer non-formed area A2.

Next, as shown in FIG. 7B, an observer observes the volume hologram laminate 10 from an observation direction D2 at a predetermined observation angle θ4 with respect to the normal direction d of the surface of the volume hologram laminate 10 while the reconstruction illumination light L having a predetermined incident angle θ3 with respect to the normal direction d of the surface of the volume hologram laminate 10 is irradiated. At this time, for example, when the recording wavelength during interference fringe recording is in the green wavelength region, the incident angle θ3 of the reproducing illumination light L is larger than the incident angle θ1 of the reproducing illumination light L shown in FIG. 7A, and the observation angle θ4 is larger than the observation angle shown in FIG. A blue reproduced image different from the color of the recording wavelength of time can be observed.

As described in the first embodiment above, in this embodiment, by controlling the shift amount of the reproduction wavelength of the volume hologram layer in the resin layer forming region, the color of the reproduced image from the volume hologram layer can be changed according to the incident angle and observation angle of the reproduction illumination light.

Generally, in a volume hologram, when monochromatic laser light is used to record interference fringes, the reproduced image is monochromatic. On the other hand, in the volume hologram laminate of the present embodiment, it is possible to change the reproduction wavelength of the volume hologram layer in accordance with the incident angle and observation angle of the reproduction illumination light in the resin layer formation region, thereby changing the color of the reproduced image from the volume hologram layer. In this case, in the resin layer formed region, the color of the reproduced image from the volume hologram layer changes according to the incident angle and observation angle of the reconstruction illumination light, while in the resin layer non-formed region, it is possible to prevent the color of the reproduced image from the volume hologram layer from changing according to the incident angle and observation angle of the reconstruction illumination light. Therefore, the anti-counterfeiting effect can be enhanced. Furthermore, in the resin layer forming region, for example, by controlling the shift amount of the reproduction wavelength of the volume hologram layer and shifting the reproduction wavelength of the volume hologram layer to a wavelength where the laser light source does not exist, duplication becomes difficult, so the anti-counterfeiting effect can be further enhanced. In addition, a volume hologram laminate having excellent design properties can be obtained.

Further, in the volume hologram laminate of the present embodiment, as described above, the volume hologram layer and the resin layer are in contact with each other. For example, after recording interference fringes in the volume hologram layer, the volume hologram laminate can be manufactured by placing a resin layer in contact with the volume hologram layer and transferring a low-molecular-weight substance such as an uncured photopolymerizable compound contained in the volume hologram layer to the resin layer. Therefore, although monochromatic laser light is used to record interference fringes, it is possible to obtain a volume hologram laminate in which the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light in the resin layer formation region, and the color of the image reproduced from the volume hologram layer changes. Furthermore, it is possible to obtain a volume hologram laminate with a high anti-counterfeiting effect by a simple method.

Each configuration of the volume hologram laminate of this embodiment will be described below.

1. Characteristics of Volume Hologram Laminate The volume hologram laminate of this embodiment can have, for example, the following first property or second property.

(1) First characteristic In the volume hologram laminate of the present embodiment, the color of the reproduced image from the volume hologram layer may be different between the resin layer forming region where the resin layer is arranged and the resin layer non-forming region where the resin layer is not arranged.

The reproduction wavelength of the volume hologram layer is usually in the visible light region, for example, 380 nm or more and 780 nm or less. The color of the reproduced image from the volume hologram layer, that is, the reproduced color, may be any color that can be identified by the human eye. In the first characteristic, the color of the reproduced image differs between the resin layer formed area and the resin layer non-formed area. The colors of the reproduced images in the resin layer formed region and the resin layer non-formed region are preferably colors having similar wavelengths, such as a combination of green and blue, or a combination of blue and blue-violet or violet.

Further, it is preferable that the reproduction color in the resin layer non-formed region is similar to the color of the recording wavelength.

Further, in this embodiment, since the reproduction wavelength of the volume hologram layer in the resin layer forming region is shifted to the short wavelength side when manufacturing the volume hologram laminate, the reproduction color in the resin layer forming region is preferably a color on the shorter wavelength side than the recording wavelength.

(2) Second characteristic In the volume hologram laminate of the present embodiment, the reproduction wavelength of the volume hologram layer may change according to the incident angle and observation angle of the reproduction illumination light in the resin layer forming region, and the color of the image reproduced from the volume hologram layer may change.

The reproduction wavelength of the volume hologram layer is usually in the visible light region, for example, 380 nm or more and 780 nm or less. The color of the reproduced image from the volume hologram layer, that is, the reproduced color, may be any color that can be identified by the human eye.

The reproduction wavelength of the volume hologram layer in the resin layer forming region can be the same as the reproduction wavelength of the volume hologram layer in the first embodiment.

In addition, in the resin layer forming region, the change in color of the reproduced image from the volume hologram layer according to the incident angle and observation angle of the reconstruction illumination light can be the same as described in the first embodiment.

In the second characteristic, in the resin layer non-formation region, the color of the reproduced image from the volume hologram layer does not change according to the incident angle of the reconstruction illumination light and the observation angle.

It is preferable that the reproduction color in the resin layer non-formed region is similar to the color of the recording wavelength, regardless of the incident angle and observation angle of the reproduction illumination light.

In this embodiment, since the reproduction wavelength of the volume hologram layer in the resin layer forming region is shifted to the short wavelength side when manufacturing the volume hologram laminate, it is preferable that one of the reproduced colors before and after the change in the resin layer forming region is a color similar to the color of the recording wavelength, and the other color is a color on the shorter wavelength side than the recording wavelength.

In the resin layer forming region, the method of changing the reproduction wavelength of the volume hologram layer and changing the color of the image reproduced from the volume hologram layer according to the incident angle and observation angle of the reproduction illumination light can be the same as the content described in the first embodiment.

2. Volume Hologram Laminated Part The volume hologram laminated part in the present embodiment is arranged on one surface of the base material, and includes, in random order, a volume hologram layer containing a polymer of a photopolymerizable compound and having interference fringes recorded thereon, and a resin layer, which is arranged in a pattern in contact with the volume hologram layer and contains a transparent resin.

(1) Resin layer The resin layer in this embodiment contains a transparent resin and is arranged in a pattern in contact with the volume hologram layer.

The material of the resin layer can be the same as the material of the resin layer in the first embodiment.

Moreover, it is preferable that the resin layer does not contain thermoplastic organic fine particles.

The thickness of the resin layer is not particularly limited as long as the reproduction wavelength of the volume hologram layer can be shifted to the short wavelength side with respect to the recording wavelength, and is appropriately adjusted according to the type of the transparent resin. As described above, by adjusting the thickness of the resin layer, the shift amount of the reproduction wavelength of the volume hologram layer can be adjusted. Therefore, it is preferable to adjust the thickness of the resin layer so that the reproduced image from the volume hologram layer can have a desired color. Specifically, the thickness of the resin layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 6 μm or less, and even more preferably 0.5 μm or more and 4 μm or less.

Also, as in the first embodiment, no interference fringes are recorded in the resin layer.

The method for forming the resin layer is not particularly limited as long as it is a method capable of forming the resin layer in a pattern, and examples thereof include gravure printing and screen printing.

(2) Volume hologram layer The volume hologram layer in this embodiment can be the same as the volume hologram layer in the first embodiment.

(2) Arrangement of volume hologram layer and resin layer The volume hologram laminated part in the present embodiment has the above-described volume hologram layer and patterned resin layer in random order. For example, the volume hologram layer and the patterned resin layer may be arranged in order from the substrate side, or the patterned resin layer and the volume hologram layer may be arranged in order from the substrate side.

3. Substrate The substrate in this embodiment can be the same as the substrate in the first embodiment.

4. Arbitrary Configuration The volume hologram laminate of this embodiment may have any configuration other than the above-described volume hologram laminate and base material, if necessary. Any configuration can be the same as any configuration in the first embodiment.

5. Volume Hologram Laminate Manufacturing Method As a method for manufacturing the volume hologram laminate of the present embodiment, for example, a manufacturing method can be used that includes, in order, a volume hologram layer forming step of forming a volume hologram layer containing a photopolymerizable compound and a photopolymerization initiator system, a photographing step of recording interference fringes in the volume hologram layer, a laminating step of arranging a resin layer in a pattern in contact with the volume hologram layer in which the interference fringes are recorded, and a heating step of heating the volume hologram layer and the resin layer in contact with each other. In addition, the method for producing a volume hologram laminate of this embodiment may further include a post-treatment step of polymerizing the uncured photopolymerizable compound after the heating step.

In this embodiment, the photographing step, the laminating step, and the heating step are performed in order, and in the heating step, the volume hologram layer and the resin layer are heated while they are in contact with each other. This transfers low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer to the resin layer, thereby causing the volume hologram layer to shrink and narrowing the interval between interference fringes. This makes it possible to obtain a volume hologram laminate in which the color of the reproduced image from the volume hologram layer differs between the resin layer formed region and the resin layer non-formed region. Also, at this time, by controlling the shift amount of the reproduction wavelength, the reproduction wavelength of the volume hologram layer changes according to the incident angle and the observation angle of the reproduction illumination light in the resin layer formation region, and a volume hologram laminate in which the color of the reproduced image from the volume hologram layer changes can be obtained.

The method for controlling the shift amount of the reproduction wavelength of the volume hologram layer is as described in the first embodiment above.

Further, each step of the method for manufacturing the volume hologram laminate of this embodiment can be the same as each step of the method for manufacturing the volume hologram laminate of the first embodiment.

III. Other Embodiments Another embodiment of the volume hologram laminate in the present disclosure has a substrate and a volume hologram laminate disposed on one surface of the substrate, the volume hologram laminate including a polymer of a photopolymerizable compound and having interference fringes recorded therein, in random order, and a resin layer containing a transparent resin disposed in contact with the volume hologram layer; The present invention provides a volume hologram laminate containing no interference fringes recorded in the resin layer.

Here, as described in the above section of the first embodiment, in the production of the volume hologram laminate, for example, after interference fringes are recorded in the volume hologram layer, a resin layer is arranged in contact with the volume hologram layer, and the volume hologram layer shrinks by transferring low-molecular-weight substances such as uncured photopolymerizable compounds contained in the volume hologram layer to the resin layer, thereby narrowing the distance between the interference fringes.

In this embodiment, the resin layer contains the same low-molecular-weight substance as the low-molecular-weight substance used in the volume hologram layer or a polymer thereof, so that the reproduction wavelength of the volume hologram layer can be shifted to the shorter wavelength side with respect to the recording wavelength during interference fringe recording. Therefore, the anti-counterfeiting effect can be enhanced. Furthermore, for example, by controlling the shift amount of the reproduction wavelength of the volume hologram layer and shifting the reproduction wavelength of the volume hologram layer to a wavelength where no laser light source exists, duplication becomes difficult, so the anti-counterfeiting effect can be further enhanced.

In the production of the volume hologram laminate of this embodiment, interference fringes are not recorded in the resin layer because the resin layer is arranged in contact with the volume hologram layer after the interference fringes are recorded in the volume hologram layer.

On the other hand, as described in Patent Document 2, by bringing a resin layer containing a resin and a polymerizable compound into contact with the volume hologram layer to transfer the polymerizable compound in the resin layer to the volume hologram layer, the reproduction wavelength of the volume hologram layer can be shifted to the longer wavelength side with respect to the recording wavelength during interference fringe recording. In this case, since the interference fringes are recorded in the volume hologram layer after the resin layer is placed in contact with the volume hologram layer, the interference fringes are also recorded in the resin layer.

Therefore, the volume hologram laminate of this embodiment is different from the volume hologram laminate described in Patent Document 2.

In the volume hologram laminate of this embodiment, the color of the image reproduced from the volume hologram layer does not change regardless of the incident angle and observation angle of the reconstruction illumination light.

As described in the section of the first embodiment above, for example, if the amount of shift in the reproduction wavelength is large, the color of the image reproduced from the volume hologram layer does not change regardless of the incident angle and observation angle of the reproduction illumination light. Therefore, by increasing the shift amount of the reproduction wavelength, it is possible to prevent the color of the reproduced image from the volume hologram layer from changing regardless of the incident angle and observation angle of the reproduction illumination light.

The method for controlling the amount of shift of the reproduction wavelength of the volume hologram layer to the short wavelength side can be the same as that described in the first embodiment.

Each configuration of the volume hologram laminate of this embodiment can be the same as each configuration of the volume hologram laminate of the first embodiment, except that the color of the reproduced image from the volume hologram layer does not change regardless of the incident angle and observation angle of the reconstruction illumination light.

Further, in this embodiment, the resin layer preferably does not contain thermoplastic organic fine particles.

B. Volume Hologram Transfer Foil A volume hologram transfer foil in the present disclosure includes the above-described volume hologram laminate and a heat seal layer disposed on the surface of the volume hologram laminate on the side of the volume hologram laminate.

FIG. 8 is a schematic cross-sectional view showing an example of the volume hologram transfer foil in the present disclosure. As illustrated in FIG. 8, the volume hologram transfer foil 20 has a volume hologram laminate 10 and a heat seal layer 21 arranged on the surface of the volume hologram laminate 10 on the side of the volume hologram laminate 2 .

In FIG. 8, the volume hologram laminated portion 2 has the resin layer 2b and the volume hologram layer 2a in order from the substrate 1 side, but although not shown, it may have a volume hologram layer and a resin layer in order from the substrate side.

According to the present disclosure, by using the volume hologram laminate described above, it is possible to obtain a volume hologram transfer foil that has a high anti-counterfeiting effect and is excellent in design.

Each configuration of the volume hologram transfer foil in the present disclosure will be described below.

1. Volume Hologram Laminate The volume hologram laminate used in the present disclosure is the same as described in the section “A. Volume Hologram Laminate” above.

As described above, the volume hologram laminate has at least a base material and a volume hologram laminate portion, but the volume hologram transfer foil of the present disclosure preferably has other configurations than the above in view of its use. Other structures preferably include, for example, a release layer and a protective layer.

(1) Release layer The release layer used in the present disclosure is a member arranged between the substrate and the volume hologram laminate in the volume hologram laminate.

As illustrated in FIG. 9 , the volume hologram laminate 10 preferably has a release layer 3 between the substrate 1 and the volume hologram laminate 2 . Since the volume hologram laminate has a release layer, the adhesive force between the substrate and the volume hologram laminate can be adjusted within an arbitrary range. Therefore, when the volume hologram laminate is transferred from the volume hologram transfer foil of the present disclosure, the peelability of the volume hologram laminate from the substrate can be improved.

Examples of materials used for the release layer include water-soluble resins, hydrophilic resins, waxes, polyethylene waxes, silicone waxes, silicone resins, fluorine resins, and acrylic resins.

The thickness of the release layer can be, for example, about 0.5 μm or more and 5 μm or less.

(2) Protective layer The protective layer used in the present disclosure is a member placed between the release layer and the volume hologram laminate, and when the volume hologram laminate is transferred using the volume hologram transfer foil in the present disclosure, it maintains the physical strength of the transferred volume hologram laminate, or enables printing such as offset printing on the outermost surface.

Materials used for the protective layer include, for example, acrylic resins, vinyl chloride-vinyl acetate copolymers, polyester resins, polymethacrylate ester resins, polyvinyl chloride resins, cellulose resins, silicone resins, chlorinated rubbers, casein, various surfactants, a mixture of two or more selected from the group consisting of metal oxides, ionizing radiation curable resins, thermosetting resins, and thermoplastic resins that react to ultraviolet light, electron beams, and the like.

The thickness of the protective layer can be, for example, about 0.5 μm or more and 5 μm or less.

In addition, when there is releasability between the base material and the protective layer, or when at least one material used for the release layer and one material used for the protective layer are mixed to form a releasable protective layer, the release layer may not be provided. In addition, when the resin layer in the volume hologram laminated portion and the base material are releasable, it is not necessary to provide a release layer or a protective layer.

2. Heat Seal Layer The heat seal layer used in the present disclosure has the function of bonding the volume hologram laminate and the transfer target when transferring the volume hologram laminate to the transfer target using the volume hologram transfer foil of the present disclosure.

The heat seal layer contains a thermoplastic resin. The thermoplastic resin is appropriately selected according to the type of transfer target, and is not particularly limited as long as it can bond the volume hologram laminated portion and the transfer target. Examples of such thermoplastic resins include maleic acid-modified vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers, polyamide resins, polyester resins, polyethylene resins, ethylene-isobutyl acrylate copolymers, butyral resins, polyvinyl acetate and copolymers thereof, ionomer resins, acid-modified polyolefin resins, (meth)acrylic resins such as acrylic and methacrylic resins, acrylic acid ester resins, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid copolymers. (Meth) acrylic acid ester copolymer, polymethyl methacrylate resin, cellulose resin, polyvinyl ether resin, polyurethane resin, polycarbonate resin, polypropylene resin, epoxy resin, phenol resin, vinyl resin, maleic acid resin, alkyd resin, polyethylene oxide resin, urea resin, melamine resin, melamine alkyd resin, silicone resin, rubber resin, styrene butadiene styrene block copolymer (SBS), styrene isoprene styrene block copolymer (SIS), styrene ethylene butylene styrene block copolymer (S) EBS), styrene ethylene propylene styrene block copolymer (SEPS), and the like. The thermoplastic resin may be used singly or in combination of two or more.

The heat seal layer may contain additives. Examples of additives include dispersants, fillers, plasticizers, antistatic agents, and the like.

The thickness of the heat-sealing layer is not particularly limited and may be appropriately selected according to the type of the material to be transferred. If the thickness is too thin, there is a possibility that the adhesiveness to the transferred material will be insufficient. Also, if it is too thick, the temperature for heating the heat seal layer becomes too high when transferring the volume hologram laminated portion from the volume hologram transfer foil of the present disclosure, which may cause damage to the base material or the like.

The heat seal layer may be a single layer or multiple layers. In the case of multiple layers, layers having the same composition may be laminated, or layers having different compositions may be laminated.

3. Arbitrary Configuration The volume hologram transfer foil in the present disclosure may have any configuration other than the above-described volume hologram laminate and heat seal layer, if necessary. As an arbitrary configuration, a configuration having a desired function can be appropriately selected and used according to the application of the volume hologram transfer foil in the present disclosure. Examples of preferred arbitrary configurations include a separator and a printed layer.

The separator is arranged on the opposite side of the heat seal layer to the volume hologram laminate, and is a member for preventing the heat seal layer from inadvertently adhering to other substances or blocking when the volume hologram transfer foil of the present disclosure is wound, and is temporarily adhered to the heat seal layer until the volume hologram transfer foil is used. As such a separator, a commonly used one can be applied, and examples thereof include fine paper, linter paper, sulfuric acid paper, glassine paper, kraft paper, polyester resin, olefin resin, and the like. As the separator, the surfaces of these members may be processed, and examples thereof include those coated with calcium carbonate, talc, silicone resin, melamine resin, or the like on both or one side of the above members.

The thickness of the separator can be the same as the thickness of a general separator, and is preferably 12 μm or more and 75 μm or less, for example.

The print layer is a member that displays, for example, characters, numbers, symbols, figures, pictures, patterns, and the like. The printed layer can be formed by a general printing method.

C. Volume Hologram Label A volume hologram label according to the present disclosure includes the above-described volume hologram laminate and an adhesive layer disposed on the surface of the volume hologram laminate on the volume hologram laminate side.

FIG. 10 is a schematic diagram showing an example of a volume hologram label in the present disclosure. As illustrated in FIG. 10, the volume hologram label 30 has a volume hologram laminate 10 and an adhesive layer 31 arranged on the surface of the volume hologram laminate 10 on the volume hologram laminate 2 side.

In FIG. 10, the volume hologram laminated portion 2 has the resin layer 2b and the volume hologram layer 2a in order from the substrate 1 side, but it may have a volume hologram layer and a resin layer in order from the substrate side, although not shown.

According to the present disclosure, by using the volume hologram laminate described above, it is possible to obtain a volume hologram label with a high anti-counterfeiting effect and excellent design.

Each configuration of the volume hologram label in the present disclosure will be described below.

1. Adhesive Layer The adhesive constituting the adhesive layer used in the present disclosure may be, for example, a heat sealing agent or a general pressure-sensitive adhesive.

As the heat-sealing agent, the thermoplastic resins described in the section "B. Volume hologram transfer foil" as the thermoplastic resin used for the heat-sealing layer can be used, so the description thereof is omitted here.

Examples of pressure-sensitive adhesives include acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives and polyester-based pressure-sensitive adhesives. Among these, it is preferable to use an acrylic pressure-sensitive adhesive that is excellent in durability and adhesiveness and low in cost. Moreover, the pressure-sensitive adhesive that forms the adhesive layer may be a solvent-type adhesive or a non-solvent-type adhesive. A photosensitive adhesive can be used as the solventless adhesive.

The acrylic pressure-sensitive adhesive contains an acrylic pressure-sensitive adhesive resin as a main component, and a cross-linking agent, a tackifier, and the like are added as necessary. The acrylic adhesive resin is mainly composed of an acrylic copolymer obtained by copolymerizing alkyl acrylate, other monomers, and functional monomers.

Alkyl acrylates have an alkyl group having 4 to 15 carbon atoms, and examples of such alkyl acrylates include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate. These acrylic acid alkyl esters may be used singly or in combination of two or more.

Other monomers include, for example, methyl acrylate, methyl methacrylate, styrene, acrylonitrile, vinyl acetate and the like. These other monomers may be used singly or in combination of two or more.

Examples of functional monomers include acrylic acid, methacrylic acid, itaconic acid, hydroxylethyl acrylate, hydroxylethyl methacrylate, propylene glycol acrylate, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, dimethylaminoethyl methacrylate, and tert-butylaminoethyl methacrylate. These functional monomers may be used singly or in combination of two or more.

The composition ratio (% by mass) of the acrylic acid alkyl ester, the other monomer and the functional monomer in the acrylic copolymer is, for example, 70-99:0-20:0.01-20, preferably 80-95:0-10:0.1-15. Further, the weight average molecular weight of the acrylic copolymer is, for example, preferably 200,000 or more and 1,200,000 or less, and more preferably 400,000 or more and 1,000,000 or less.

A cross-linking agent is an additive for improving the cohesive strength of the adhesive layer. Such cross-linking agents include room temperature cross-linking agents and heat cross-linking agents.

A room-temperature cross-linking type cross-linking agent is a cross-linking agent that cross-links an acrylic pressure-sensitive adhesive by aging treatment under room temperature conditions. Examples of such room temperature cross-linking agents include isocyanate compounds, polyfunctional epoxy compounds, and metal chelate compounds such as aluminum and titanium. Among them, it is preferable to use an isocyanate compound or a polyfunctional epoxy compound.

Examples of isocyanate compounds include polyisocyanate compounds, trimers of polyisocyanate compounds, urethane prepolymers having terminal isocyanate groups obtained by reacting a polyisocyanate compound with a polyol compound, or trimers of such urethane prepolymers. Specific examples of polyisocyanate compounds include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate, and the like. are mentioned.

The room-temperature cross-linking agents may be used singly or in combination of two or more.

The heat cross-linking type cross-linking agent is a cross-linking agent that cross-links the acrylic pressure-sensitive adhesive by aging treatment by heating. Examples of such a heat-crosslinking type cross-linking agent include a methylol group-containing compound obtained by reacting formaldehyde with melamine, benzogamine, urea, or the like, or a compound in which a part or all of the methylol group of the methylol group-containing compound is etherified with an aliphatic alcohol.

The content of the room temperature cross-linking agent is, for example, preferably 0.005 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, relative to 100 parts by mass of the acrylic copolymer. The content of the heat-crosslinking cross-linking agent is, for example, preferably 0.01 parts by mass or more and 25 parts by mass or less, more preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer.

The tackifier is added as necessary for the purpose of imparting adhesive strength, tack or viscoelasticity to the pressure-sensitive adhesive and improving the adhesive performance of the pressure-sensitive adhesive, and may not be added if unnecessary. Examples of tackifiers include rosin-based resins, terpene-based resins, and xylene-based resins. The content of the tackifier in the acrylic pressure-sensitive adhesive is, for example, 50% by mass or less, preferably 40% by mass or less.

Various additives such as antioxidants and UV absorbers may be added to the pressure-sensitive adhesive within a range that does not impair its performance. Moreover, when using a photosensitive adhesive that is cured by irradiation with ultraviolet light or visible light, a polymerization initiator is added. As the polymerization initiator, for example, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ethers and the like can be used. When using a photosensitive adhesive that is cured by electron beam irradiation, no polymerization initiator is added.

The thickness of the adhesive layer is, for example, 4 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less.

2. Volume Hologram Laminate The volume hologram laminate used in the present disclosure is the same as that described in the section “A. Volume Hologram Laminate” above.

3. Arbitrary Configuration The volume hologram label in the present disclosure may have any configuration other than the volume hologram laminate and adhesive layer described above, as necessary. As an arbitrary configuration, a configuration having a desired function can be appropriately selected and used according to the application of the volume hologram label in the present disclosure. Examples of preferred arbitrary configurations include a separator, a printed layer, a colored layer, and the like. The separator is the same as that described in the section "B. Volume hologram transfer foil" above. Also, the printed layer is the same as described in the above section "B. Volume hologram transfer foil".

In the volume hologram label of the present disclosure, the adhesive layer may have a colored layer in the layer. For example, the colored layer serves as the background color of the volume hologram layer, and an image with excellent contrast can be obtained. Although it is conceivable to add a coloring agent to the adhesive layer, it is possible to prevent the coloring agent from migrating to the volume hologram layer and having an adverse effect by having a colored layer in the adhesive layer. When the adhesive layer has a colored layer in the layer, for example, as shown in FIG. 11, the first adhesive layer 31a, the colored layer 32, and the second adhesive layer 31b may be arranged in order from the volume hologram laminate 2 side.

Examples of the colored layer include a colored adhesive layer, a printed layer, a reflective layer, a colored resin film, and the like.

A colored adhesive layer contains, for example, a pressure sensitive adhesive and a colorant. The pressure-sensitive adhesive is the same as the pressure-sensitive adhesive used for the adhesive layer. Colorants can include, for example, pigments, dyes, or mixtures thereof. The content of the coloring agent in the colored adhesive layer is, for example, 1% by mass or more and 40% by mass or less, preferably 10% by mass or more and 30% by mass or less. The thickness of the colored adhesive layer is, for example, 4 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less.

For example, a metal film can be used as the reflective layer. Metal materials contained in the metal film include, for example, metals such as Cr, Ti, Fe, Co, Ni, Cu, Ag, Au, Ge, Al, Mg, Sb, Pb, Pd, Cd, Bi, Sn, Se, In, Ga, Rb, and oxides and nitrides thereof. These may be used individually by 1 type, and may be used in combination of 2 or more type. The thickness of the metal film is, for example, 1 nm or more and 10000 nm or less, preferably 20 nm or more and 200 nm or less.

Examples of the colored resin film include a resin film containing a coloring agent and a transparent resin film having a colored layer on one side thereof.

D. Card The card in the present disclosure has a core sheet, an adhesive layer, the volume hologram laminate described above, and a transparent sheet in this order.

12(a) and (b) are a schematic plan view and a cross-sectional view showing an example of a card according to the present disclosure, and FIG. 12(b) is a cross-sectional view taken along line AA of FIG. 12(a). As shown in FIGS. 12A and 12B, the card 40 has a core sheet 41, an adhesive layer 43, a volume hologram laminate 10, and a transparent sheet 42 in this order. In addition to the volume hologram laminate 10, the card 40 may be provided with information such as a photographic image 44 and characters 45, for example.

According to the present disclosure, by using the volume hologram laminate described above, it is possible to obtain a card having a high anti-counterfeiting effect and an excellent design.

Each configuration of the card in the present disclosure will be described below.

1. Volume Hologram Laminate The volume hologram laminate used in the present disclosure is the same as that described in the section “A. Volume Hologram Laminate” above.

The volume hologram laminate is arranged so that the surface on the side of the volume hologram laminate faces the core sheet.

2. Core Sheet The core sheet in the present disclosure is a member that becomes the base of the card. Examples of core sheets include resin sheets such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (PET-G), polyvinyl chloride (PVC), and polycarbonate (PC). The outline of the core sheet is the same as the outline of the card. The core sheet may be transparent or opaque. The color of the core sheet is not particularly limited and can be any color. The core sheet may be composed of, for example, a resin sheet, and a colored layer may be arranged on one side of the resin sheet.

3. Transparent Sheet The transparent sheet in the present disclosure is a member that protects the volume hologram laminate. Also, when the transparent sheet is arranged on the outermost surface of the card, it can function as an oversheet that protects the surface of the card.

The transparent sheet may be any transparent sheet, and examples thereof include resin sheets such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (PET-G), polyvinyl chloride (PVC), and polycarbonate (PC). The surface of the transparent sheet may be, for example, mirror-like or matte-like. The outline of the transparent sheet is the same as the outline of the card.

4. Adhesive Layer The adhesive layer in the present disclosure is a member for bonding the volume hologram laminate and the core sheet. An example of an adhesive that forms the adhesive layer is a heat sealing agent. As the heat-sealing agent, the thermoplastic resins described in the section "B. Volume hologram transfer foil" as the thermoplastic resin used for the heat-sealing layer can be used, so the description thereof is omitted here.

5. Arbitrary Configuration The card in the present disclosure may have any configuration other than the core sheet, the adhesive layer, the volume hologram laminate, and the transparent sheet, if necessary. As an arbitrary configuration, a configuration having a desired function can be appropriately selected and used according to the application of the card in the present disclosure. Optional structures include, for example, a second adhesive layer, a printed layer, an intermediate sheet, an oversheet, an interlayer adhesive layer, an IC module containing an IC chip, an inlet containing an IC chip and an antenna, a magnetic stripe, and the like.

The card according to the present disclosure may have a second adhesive layer 46 between the volume hologram laminate 10 and the transparent sheet 42, as shown in FIG. 13, for example. The second adhesive layer is a member for bonding the volume hologram laminate and the transparent sheet. An example of an adhesive that forms the second adhesive layer is a heat sealing agent. As the heat-sealing agent, the thermoplastic resins described in the section "B. Volume hologram transfer foil" as the thermoplastic resin used for the heat-sealing layer can be used, so the description thereof is omitted here.

The card in the present disclosure may have a printed layer on at least one of the surface of the transparent sheet opposite to the core sheet and between the core sheet and the volume hologram laminate. In addition, the card in the present disclosure may further have a printed layer on the side of the core sheet opposite to the transparent sheet. The print layer is a member that displays, for example, characters, numbers, symbols, figures, pictures, patterns, and the like. The print layer may be, for example, a laser print layer. Further, when a printed layer is arranged on at least one of the surface of the transparent sheet opposite to the core sheet and between the core sheet and the volume hologram laminate, the printed layer and the volume hologram layer of the volume hologram laminate may be arranged so as to overlap or not overlap when viewed in plan. In addition, when a printed layer is arranged on the surface of the transparent sheet opposite to the core sheet, the printed layer may have an opening so as to overlap the volume hologram laminate in plan view, for example. The volume hologram laminate can be confirmed in the opening.

6. Card manufacturing method As a method for manufacturing a card according to the present disclosure, for example, when the adhesive layer contains a heat sealing agent, a method of placing an adhesive layer on the surface of the volume hologram laminate side of the volume hologram laminate, placing the volume hologram laminate with an adhesive layer on one surface of the core sheet so that the adhesive layer side faces each other, placing a transparent sheet so as to cover the volume hologram laminate with an adhesive layer, and then performing thermocompression bonding from above the transparent sheet. As a result, the adhesive layer is thermally melted, and the volume hologram laminate is adhered to the core sheet. Further, when an adhesive layer is arranged on the surface of the volume hologram laminate on the side of the volume hologram lamination part and a second adhesive layer is arranged on the surface of the volume hologram laminate on the substrate side, the volume hologram laminate can be adhered to the core sheet and the transparent sheet by thermally melting the adhesive layer and the second adhesive layer during thermocompression bonding.

Further, for example, when the core sheet has a concave portion, the adhesive layer-attached volume hologram laminate may be placed in the concave portion of the core sheet in manufacturing the card.

7. Use of Card A card in the present disclosure is, for example, an information recording medium on which various types of information such as personal information and confidential information are recorded. Examples of cards include various IC cards, driver's licenses, insurance cards, employee ID cards, membership cards, ID cards such as student ID cards, credit cards, debit cards, cash cards, card keys, point cards, prepaid cards, and the like.

E. Data Page The data page in the present disclosure has a first transparent sheet, an IC chip holding sheet containing an IC chip inside, a core sheet, an adhesive layer, the volume hologram laminate described above, and a second transparent sheet in this order.

FIG. 14 is a schematic cross-sectional view showing an example of a data page in this disclosure. As shown in FIG. 14, the data page 50 has a first transparent sheet 51, an IC chip holding sheet 52 containing an IC chip 61 and an antenna 62 inside, a core sheet 53, an adhesive layer 55, a volume hologram laminate 10, and a second transparent sheet 54 in this order. The core sheet 53 has a connection portion 53a for incorporating the data page 50 into a booklet. For example, as shown in FIG.

According to the present disclosure, a data page having a high forgery prevention effect can be obtained by using the above-described volume hologram laminate.

Each configuration of the data page in the present disclosure will be described below.

1. Volume Hologram Laminate The volume hologram laminate used in the present disclosure is the same as that described in the section “A. Volume Hologram Laminate” above.

The volume hologram laminate can be arranged so that the surface on the side of the volume hologram laminate faces the core sheet.

2. Core Sheet A core sheet is a member with connecting parts for incorporating data pages into a booklet. Examples of the core sheet include a fiber sheet and a sheet in which resin sheets are arranged on both sides of a fiber sheet.

Also, the core sheet may have an opening, for example, so as to overlap the volume hologram laminate in a plan view. At the opening, the volume hologram stack can be seen from one or both sides of the data page.

3. IC Chip Holding Sheet The IC chip holding sheet is a member containing an IC chip inside. The IC chip holding sheet can contain an antenna and the like in addition to the IC chip inside.

The IC chip holding sheet may also serve as the core sheet.

The IC chip holding sheet may have any structure as long as it can contain an IC chip, an antenna, etc., and can have a multilayer structure, for example. Resin sheets such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (PET-G), polyvinyl chloride (PVC), and polycarbonate (PC) can be used as the IC chip holding sheet.

Also, the IC chip holding sheet may have, for example, an opening so as to overlap the volume hologram laminate in a plan view. At the opening, the volume hologram stack can be seen from one or both sides of the data page.

4. First Transparent Sheet and Second Transparent Sheet The first transparent sheet and the second transparent sheet are members that protect the surface of the data page. The first transparent sheet and the second transparent sheet may be sheets having transparency. For example, resin sheets such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (PET-G), polyvinyl chloride (PVC), and polycarbonate (PC) can be used.

5. Adhesive Layer The adhesive layer in the present disclosure is a member for bonding the volume hologram laminate and the core sheet. An example of an adhesive that forms the adhesive layer is a heat sealing agent. As the heat-sealing agent, the thermoplastic resins described in the section "B. Volume hologram transfer foil" as the thermoplastic resin used for the heat-sealing layer can be used, so the description thereof is omitted here.

6. Arbitrary Configuration The data page in the present disclosure may have any arbitrary configuration as necessary in addition to the first transparent sheet, IC chip holding sheet, core sheet, volume hologram laminate, and second transparent sheet. As an arbitrary configuration, a configuration having a desired function can be appropriately selected and used according to the use of the data page in the present disclosure. Optional structures include, for example, a laser-printed layer, a white layer, a printed layer, an intermediate layer, and the like.

F. Brochures The brochures in this disclosure comprise the data pages described above.

FIG. 15 is a schematic perspective view showing an example of booklets in the present disclosure. As shown in FIG. 15, the brochure 70 comprises a cover 71, data pages 50 and pages 72, and the data page 50 is attached to the cover 71 and other pages 72 via connecting portions 53a, for example by stitching.

Examples of booklets include passports and the like.

Note that the present disclosure is not limited to the above embodiments. The above embodiment is an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and produces similar effects is included in the technical scope of the present disclosure.

EXAMPLES The present disclosure will be specifically described below with reference to Examples.

[Example 1]
(1) Preparation of first film and second film First, a first film and a second film were separately prepared by independent steps.

(Production of second film)
A polyethylene terephthalate (PET) film (Cosmoshine A4160; manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm was used as the second substrate, and a resin composition in which polymethyl methacrylate was dissolved in a solvent was applied to the second substrate using a bar coater so that the film thickness was 1 μm, followed by drying to form a resin layer, thereby obtaining a second film.

(Preparation of first film)
A polyethylene terephthalate (PET) film (Lumirror T60; manufactured by Toray Industries, Inc.) having a thickness of 50 μm was used as the first substrate, and a volume hologram layer composition having the following composition was applied onto the first substrate by a gravure coating method at a speed of 30 m/min and dried at 100° C. to volatilize the solvent, thereby forming a volume hologram forming layer having a thickness of approximately 10 μm. Furthermore, a 38 μm-thick polyethylene terephthalate (PET) film (SP-PET; manufactured by Mitsui Chemicals Tocello Co., Ltd.) whose surface was release-treated was laminated on the volume hologram forming layer to obtain a first film.

<Composition of composition for volume hologram layer>
・Polymethyl methacrylate 100 parts by mass ・9,9-bis(4-acryloxydiethoxyphenyl)fluorene 5 parts by mass ・1,6-hexanediol diglycidyl ether 70 parts by mass ・Diphenyliodonium hexafluoroantimonate 5 parts by mass ・3,9-diethyl-3'-carboxymethyl-2,2'-thiocarbocyanine iodonium salt 1 part by mass

(2) Production of Volume Hologram Laminate Next, a hologram was recorded on the volume hologram forming layer, and a resin layer was laminated. Specifically, first, the release PET film was peeled off from the first film, the exposed layer for forming a volume hologram was laminated on the hologram original plate, and a laser beam with a wavelength of 532 nm was used to capture and record a Lippmann hologram at an incident angle of 45° and an output angle of 0°. Next, the first film was peeled off from the hologram master, and the resin layer surface of the second film was laminated on the exposed volume hologram layer surface to obtain a laminate having the second substrate, the resin layer, the volume hologram layer, and the first substrate in this order.

Next, the laminated body was heated to shift the reproduction wavelength of the volume hologram layer and then fixed. Specifically, the laminate was maintained in an atmosphere of 90° C. for 3 minutes, and then irradiated with ultraviolet rays of 2500 mJ/cm ² from a high-pressure mercury lamp for fixing. Thus, a volume hologram laminate was obtained.

[Comparative Example 1]
A volume hologram laminate was produced in the same manner as in Example 1, except that in the production of the second film, a second film having only the second base material was used without forming a resin layer on the second base material, and in the production of the volume hologram laminate, a laminate having the second base material, the volume hologram layer, and the first base material was obtained in this order.

[Evaluation 1]
First, the volume hologram laminate was irradiated with white light as reconstruction illumination light at an incident angle of about 45°, and the volume hologram laminate was observed at an observation angle of about 0° from the same side as the reconstruction illumination light. When the color of the reproduced image at this time was visually confirmed, the reproduced color of both the volume hologram laminate of Example 1 and the volume hologram laminate of Comparative Example 1 was green. Photographs of reproduced images of the volume hologram laminate of Example 1 and the volume hologram laminate of Comparative Example 1 at this time are shown in FIGS. 16(a) and 17(a), respectively. Next, the volume hologram laminate was irradiated with white light as reconstruction illumination light at an incident angle of about 70°, and the volume hologram laminate was observed at an observation angle of about 15° from the same side as the reconstruction illumination light. When the color of the reproduced image at this time was visually confirmed, the reproduced color of the volume hologram laminate of Example 1 was blue, while the reproduced color of the volume hologram laminate of Comparative Example 1 was green. Photographs of reproduced images of the volume hologram laminate of Example 1 and the volume hologram laminate of Comparative Example 1 at this time are shown in FIGS. 16(b) and 17(b), respectively. From these results, it was confirmed that in the volume hologram laminate of Example 1, the reproduced wavelength changed and the reproduced color changed depending on the incident angle and observation angle of the reconstruction illumination light.

In addition, the volume hologram laminate of Example 1 was irradiated with white light as reconstruction illumination light at an incident angle of about 45°, and the volume hologram laminate was observed from the same side as the reconstruction illumination light at an observation angle of about 0°. Then, the volume hologram laminate was observed while gradually changing the incident angle of the reconstruction illumination light from about 45° to about 70° and the observation angle from about 0° to about 15°. At this time, the color of the reproduced image changed continuously from green to blue.

[Example 2]
(1) Preparation of the third film A polyethylene terephthalate (PET) film (Lumirror T60; manufactured by Toray Industries, Inc.) having a thickness of 50 µm was used as the third base material, and polyethylene wax and polymethyl methacrylate were dissolved in a solvent on the third base material. Then, a resin composition in which polymethyl methacrylate was dissolved in a solvent was applied onto the release layer using a bar coater so as to have a film thickness of 1 μm, and dried to form a resin layer. As a result, a third film having a third substrate, a release layer, and a resin layer in this order was obtained.

(2) Production of Volume Hologram Laminate Next, a hologram was recorded on the volume hologram forming layer, and a resin layer was laminated. Specifically, first, the release PET film was peeled off from the first film, the exposed volume hologram forming layer was laminated on the hologram original plate, and a laser beam with a wavelength of 532 nm was used to capture and record a Lippmann hologram at an incident angle of 45° and an output angle of 0°. Next, the first film was peeled off from the original hologram plate, and the resin layer surface of the third film was laminated on the exposed volume hologram layer surface to obtain a laminate having the third base material, the release layer, the resin layer, the volume hologram layer, and the first base material in this order.

Next, the laminated body was heated to shift the reproduction wavelength of the volume hologram layer and then fixed. Specifically, after the laminate was maintained in an atmosphere of 90° C. for 3 minutes, it was fixed by irradiating ultraviolet rays of 2500 mJ/cm ² from a high-pressure mercury lamp.

Next, the first substrate was peeled off from the laminate, and a heat-sealing agent composition in which an ethylene-vinyl acetate copolymer was dissolved in a solvent was applied to the exposed volume hologram layer using a bar coater so that the film thickness was 5 μm, followed by drying to form a heat-sealing layer. Thus, a volume hologram transfer foil was obtained.

[Example 3]
A volume hologram laminate was produced in the same manner as in Example 1. Next, the first substrate was peeled off from the volume hologram laminate, and a pressure-sensitive adhesive composition in which an acrylic resin (PE-118; manufactured by Nissetsu Co., Ltd.) was dissolved in a solvent was applied to the exposed volume hologram layer with a bar coater to a thickness of 20 μm, and dried to form a pressure-sensitive adhesive layer. A volume hologram label was thus obtained.

[Example 4]
A volume hologram laminate was produced in the same manner as in Example 1. Next, the first substrate was peeled off from the volume hologram laminate, and an adhesive composition in which a polyester resin was dissolved in a solvent was applied to the exposed volume hologram layer using a bar coater so as to have a thickness of 10 μm, followed by drying to form an adhesive layer, thereby obtaining a laminate having the second substrate, resin layer, volume hologram layer, and adhesive layer in this order. Next, the core sheet, the laminate, and the transparent sheet were laminated in this order, and heated and pressed to produce a card. The laminate was arranged so that the surface of the adhesive layer was in contact with the core sheet.

[Example 5]
A laminate having a second substrate, a resin layer, a volume hologram layer, and an adhesive layer in this order was obtained in the same manner as in Example 4. Next, the first transparent sheet, the IC chip holding sheet containing the IC chip, the core sheet, the laminate, and the second transparent sheet were laminated in this order, and heated and pressed to produce a data page. The laminate was arranged so that the surface of the adhesive layer was in contact with the core sheet.

[Evaluation 2]
When Examples 2 to 5 were evaluated in the same manner as in Evaluation 1, the same results as in Example 1 were obtained.

[Example 6]
(1) Preparation of the fourth film A polyethylene terephthalate (PET) film (Cosmoshine A4160; manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm was used as the fourth substrate, and a resin composition in which polymethyl methacrylate was dissolved in a solvent was applied on the fourth substrate in a pattern with a screen coater so that the film thickness was 1 μm, and dried to form a patterned resin layer. As a result, a fourth film having a fourth substrate and a patterned resin layer was obtained.

(2) Production of Volume Hologram Laminate Next, a hologram was recorded on the layer for forming a volume hologram, and a patterned resin layer was laminated. Specifically, first, the release PET film was peeled off from the first film, the exposed volume hologram forming layer was laminated on the hologram original plate, and a laser beam with a wavelength of 532 nm was used to capture and record a Lippmann hologram at an incident angle of 45° and an output angle of 0°. Next, the first film was peeled off from the original hologram plate, and the patterned resin layer surface of the fourth film was laminated on the exposed volume hologram layer surface to obtain a laminate having the fourth substrate, the patterned resin layer, the volume hologram layer, and the first substrate in this order.

Next, the laminated body was heated to shift the reproduction wavelength of the volume hologram layer and then fixed. Specifically, after the laminate was maintained in an atmosphere of 90° C. for 3 minutes, it was fixed by irradiating ultraviolet rays of 2500 mJ/cm ² from a high-pressure mercury lamp.

[Evaluation 3]
In Example 6, the volume hologram laminate was irradiated with white light as reconstruction illumination light at an incident angle of about 45°, and the volume hologram laminate was observed from the same side as the reconstruction illumination light at an observation angle of about 0°. Then, the volume hologram laminate was observed while gradually changing the incident angle of the reconstruction illumination light from about 45° to about 70° and the observation angle from about 0° to about 15°. The reproduced image of the volume hologram layer in the resin layer non-formed region remained green, but the reproduced image of the volume hologram layer in the resin layer formed region continuously changed from green to blue.

Reference Signs List 1 Base material 1a First base material 1b Second base material 2 Volume hologram laminate 2a Volume hologram layer 2b Resin layer 3 Release layer 10 Volume hologram laminate 11 Resin film 20 Volume hologram transfer foil 21 Heat seal layer 30 Volume hologram label 31 Adhesive layer 31a First adhesive layer 3 1b... Second adhesive layer 32... Colored layer 40... Card 41... Core sheet 42... Transparent sheet 43... Adhesive layer 44... Photographic image 45... Characters 46... Second adhesive layer 50... Data page 51... First transparent sheet 52... IC chip holding sheet 53... Core sheet 53a... Connection part 54... Second transparent sheet 5 5... Adhesive layer 61... IC chip 62... Antenna 70... Booklets 71... Cover 72... Other pages

Claims (12)

A volume hologram laminate having a substrate and a volume hologram laminate disposed on one surface of the substrate,
The volume hologram laminated portion includes a volume hologram layer containing a polymer of a photopolymerizable compound and having interference fringes recorded therein, and a resin layer disposed in contact with the volume hologram layer and containing a transparent resin, in random order,
A volume hologram laminate in which the reproduction wavelength of the volume hologram layer changes and the color of the reproduced image from the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light. 2. The volume hologram laminate according to claim 1, wherein the reproduction wavelength of the volume hologram layer gradually changes when the incident angle and first observation angle of the first reconstruction illumination light are gradually changed to the second reproduction illumination light and second observation angle. A volume hologram laminate having a substrate and a volume hologram laminate disposed on one surface of the substrate,
The volume hologram laminate includes, in random order, a volume hologram layer containing a polymer of a photopolymerizable compound and having interference fringes recorded thereon, and a resin layer containing a transparent resin and arranged in a pattern in contact with the volume hologram layer. 4. The volume hologram laminate according to claim 3, wherein the color of the reproduced image from the volume hologram layer differs between the resin layer forming region where the resin layer is arranged and the resin layer non-forming region where the resin layer is not arranged. 4. The volume hologram laminate according to claim 3, wherein in the resin layer forming region where the resin layer is arranged, the reproduction wavelength of the volume hologram layer changes according to the incident angle and observation angle of the reproduction illumination light, and the color of the reproduced image from the volume hologram layer changes. 6. The volume hologram laminate according to claim 5, wherein when the incident angle of the first reconstruction illumination light and the first observation angle are gradually changed to the incident angle of the second reconstruction illumination light and the second observation angle, the reproduction wavelength of the volume hologram layer gradually changes in the resin layer forming region. A volume hologram laminate according to any one of claims 1 to 6;
a heat seal layer disposed on the surface of the volume hologram laminate on the side of the volume hologram laminate;
A volume hologram transfer foil. 8. The volume hologram transfer foil according to claim 7, wherein said volume hologram laminate has a release layer between said volume hologram laminate and said substrate. A volume hologram laminate according to any one of claims 1 to 6;
an adhesive layer disposed on the surface of the volume hologram laminate on the side of the volume hologram laminate;
A volume hologram label having A card comprising a core sheet, an adhesive layer, the volume hologram laminate according to any one of claims 1 to 6, and a transparent sheet in this order. A data page having, in this order, a first transparent sheet, an IC chip holding sheet containing an IC chip therein, a core sheet, an adhesive layer, the volume hologram laminate according to any one of claims 1 to 6, and a second transparent sheet. A brochure comprising the data page of claim 11 .

Images