JP5379645B2 - Transparent laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent laminated film used for relief transparent hologram or the like, having high reflectance, excellent transmission, optimal refractive index, and brightness, in particular, good balance of the brightness and refractive index, and further, improved visual conditions. <P>SOLUTION: The transparent laminated film 10 has a transparent titanium oxide layer 12 formed on at least one face of a transparent base material 11, has a thickness of the transparent titanium oxide layer 12 of 80-120 nm, an average particle size of 10-17 nm, and the brightness of 42-56 cd/m<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a transparent laminated film having an optimum luminance when visually observed, and more particularly to a transparent laminated film having an optimum luminance balanced with light reflectivity used for relief transparent holograms and the like.

  Providing a transparent, highly reflective reflective layer is very important for optical applications. For example, uses such as improving designability and visibility are conceivable. Among them, in particular, diffraction gratings and relief holograms are formed on cards such as credit cards and cash cards, book covers, record jackets, etc. due to their unique glitter design effect and security due to manufacturing difficulty. Used. Although there are various hologram recording methods, there is a relief hologram that records interference fringes corresponding to the wavefront of light from an object as a fine uneven pattern on the surface of the material. Since the relief hologram can be easily duplicated in large quantities by a press technique, it is often used for the above-mentioned purposes.

  In order to easily observe the reconstructed image of the relief hologram, strong reflected light intensity is required. However, since the relief layer of the relief hologram is generally made of synthetic resin, the relief forming surface (resin) and air The reflected light intensity at the interface having a difference in refractive index is small, so that the hologram is difficult to see. For example, when a relief hologram is formed with a resin having a refractive index of n = 1.5, the reflectance on the relief forming surface: R is very low as R = about 4% by the Fresnel formula, and the hologram effect is insufficient. It is. Therefore, a transparent layer having a high refractive index and a high light reflectivity is provided on the relief surface of the relief hologram so that the relief hologram can be easily seen.

  In Patent Document 1, the composition of TiOxNyCz (x = 1.0 to 1.8, y = 0.5 to 1.0, z = 0.3 to 1.5 is formed on at least one surface of the transparent substrate 11. ) Having a transparent metal nitride oxide layer having a thickness of 10 to 200 nm and a refractive index of 1.8 to 2.6 (wavelength λ = 550 nm), and alternating with other low refractive index layers In addition, it has a relief forming layer between the transparent substrate and the metal nitride oxide layer, and further has a diffusion layer or a light diffraction layer, which is transparent and has high reflected light intensity. For example, a highly light-reflective transparent laminated film, a light diffusion reflection film, and a light diffraction reflection film that exhibit a sufficient hologram effect, light diffusion effect, and light diffraction effect are disclosed.

  Patent Document 2 discloses a hologram laminate having a hologram layer and a reflective layer formed on the hologram layer, wherein the hologram layer contains fine particles, and the refractive index of the fine particles is determined by the hologram layer. A hologram laminate is disclosed, which is smaller than the average refractive index of other components contained therein, and which can obtain a reproduced image of a hologram that is brighter than before.

  Patent Document 3 includes at least a hologram layer having a hologram pattern, a black reflective layer having a UV-visible light transmittance of 10 to 40%, and a fluorescent printed layer having a hidden pattern, and preferably the thickness of the black reflective layer. Is a metal titanium thin film with a thickness of 10 to 30 nm, and a hidden pattern that is not normally visible can be visually recognized by irradiation with ultraviolet rays. A black hologram, a hologram label, and a hologram transfer foil are disclosed.

JP 2005-119259 A JP 2005-55473 A JP 2007-72188 A

  Transparent laminated films used for relief transparent holograms, etc. require high reflectivity, excellent transparency, optimal refractive index, brightness, etc. There is an increasing demand for transparent laminated films with improved resistance.

  This invention is made | formed in view of such a situation, has the optimal brightness | luminance with few dispersion | variations with high reflectance, and provides a transparent laminated film with a very favorable visual state.

In the transparent laminated film having a transparent titanium oxide layer used for a relief transparent hologram or the like in which the visual state is important, the present inventors are required to have transparency and high light reflectance, and the evaluation includes reflectance, There are factors such as transmittance, refractive index, and brightness. Among them, it is best to evaluate the brightness that most affects the visual sense, the so-called glaring level, with particular emphasis on eliminating variations in brightness. Thus, it was found that when the value was set to 42 to 56 cd / m ² , the transparent laminated film for relief transparent hologram exhibited an excellent effect balanced with the reflectance. It was also found that the brightness and the balance were most optimal when the reflectance was 17 to 27%.

Luminance is a quantity that represents the degree of brightness on the surface of an object, and is the value obtained by dividing the luminous intensity from a point on the diverging surface toward the observation direction by the orthogonal projection area of the diverging surface including that point in the observation direction. . Unit is candela per square
1256625236796_0
It is. Seen with eyes
1256625236796_1
Since the intensity of is proportional to the brightness of what you are looking at, brightness is the fundamental amount when looking at things. For example, when a character or a pattern in a relief transparent hologram is viewed, the character or the pattern becomes easier to see as the brightness increases under the condition that there is no shiny reflection from the relief transparent hologram and no glare. This tendency becomes more prominent when looking at characters or designs that do not have a good contrast.

The transparent laminated film of the present invention is a transparent laminated film having a transparent titanium oxide layer formed on at least one surface of a transparent substrate, wherein the titanium oxide layer has a thickness of 80 to 120 nm and an average particle size of 10 a ～17Nm, luminance 42~56cd / ^m are ^two der, characterized in that is manufactured using the electron beam heating type deposition apparatus.
When the luminance is less than 42 cd / m ² , the transparency is increased but the reflectance is decreased, and when the luminance exceeds 56 cd / m ² , the reflectance is increased but the transparency is decreased. In any case, as a transparent laminated film for relief transparent holograms Obstacles to the visual condition when used. The luminance varies greatly depending on the visual condition, and in order to stabilize this at 42 to 56 cd / m ² , the particle size of the transparent titanium oxide layer can be optimized, that is, obtained by setting the average particle size to 10 to 17 nm. I can do it. When the average particle size is less than 10 nm, the luminance exceeds 56 cd / m ^2, and when the average particle size exceeds 17 nm, the luminance is less than 42 cd / m ² . Furthermore, the weather resistance of the layer itself is also improved as a secondary effect that the average particle diameter is in a narrow range. The layer thickness is optimally 80 to 120 nm, and if it is less than 80 nm, the function as a reflective film is lowered, and if it exceeds 120 nm, the transparency is lowered.

  The transparent laminated film of the present invention is characterized in that a relief forming layer is provided between the transparent substrate and the transparent titanium oxide layer. The hologram on the surface of the relief forming layer can be vividly observed by the transparent titanium oxide layer having the optimum luminance balanced with the reflectance.

  According to the present invention, it is possible to provide a transparent laminated film having an optimum luminance balanced with a reflectance and a good visual state, and particularly suitable for a relief transparent hologram.

FIG. 1 is a schematic view of a transparent laminated film according to the first embodiment of the present invention. FIG. 2 is a schematic view of the transparent laminated film of the second embodiment of the present invention. FIG. 3 is a longitudinal sectional view of an electron beam heating vapor deposition apparatus used in the practice of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A transparent laminated film 10 according to the first embodiment shown in FIG. 1 has a transparent titanium oxide layer 12 formed on at least one surface of a transparent substrate 11. The thickness of the transparent substrate 11 is 15 to 40 μm, the thickness of the titanium oxide layer 12 is 80 to 120 nm, the average particle size is 10 to 17 nm, the luminance is 42 to 56 cd / m ² , and the reflectivity is. 17-27%.

As a material of the transparent substrate 11, various materials can be applied depending on the application. For example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyamide resins such as nylon (nylon 6), polyolefin resins such as polyethylene, polypropylene, polybutene, or polymethylpentene, and cyclics such as polynorbonene Examples include polyolefin resins, vinyl resins, (meth) acrylic resins, styrene resins, polyvinyl alcohol resins, cellophane, cellulose films such as cellulose triacetate, and polycarbonate resins. Moreover, it may be a copolymer resin containing these resins as a main component, a mixture (including polymer alloy), or a laminate composed of a plurality of layers, and may be a stretched film or an unstretched film, but the strength is improved. For this purpose, a film stretched in a uniaxial direction or a biaxial direction is preferable. Usually, polyester films such as polyethylene terephthalate and polyethylene naphthalate are preferably used in view of mechanical strength and cost, and polyethylene terephthalate is most suitable.
Although the thickness of the transparent base material 11 can apply about 2.5-800 micrometers, it is preferable to set within the range of 15-40 micrometers.

The titanium oxide layer 12 is a titanium oxide thin film obtained by a vacuum thin film method such as a vacuum deposition method, a sputtering method, or an ion plating method on at least one surface of the transparent substrate 11, and has a layer thickness of 80 to 120 nm. The average particle size is 10 to 17 nm, the luminance is 42 to 56 cd / m ² , and the reflectance is 17 to 27%.
The most important factor for the titanium oxide layer 12 is the luminance. When the luminance is less than 42 cd / m ² , the transparency increases but the reflectance decreases. When the luminance exceeds 56 cd / m ² , the reflectance increases but the transparency is In any case, the visual condition when used as a transparent laminated film for a relief-forming hologram is hindered. The luminance varies widely, and in order to stabilize this at 42 to 56 cd / m ² , the transparent titanium oxide film can be obtained by optimizing the particle size, that is, by setting the average particle size to 10 to 17 nm. When the average particle size is less than 10 nm, the luminance increases beyond 56 cd / m ² , and when the average particle size exceeds 17 nm, the luminance becomes less than 42 cd / m ² . Furthermore, the durability of the layer itself is also improved as a secondary effect that the average particle diameter is in a narrow range. The layer thickness is optimally 80 to 120 nm, and if it is less than 80 nm, the function as a reflective film is lowered, and if it exceeds 120 nm, the transparency is lowered.

  As a method for producing such a titanium oxide layer 12, it is preferable to use an electron beam heating vapor deposition apparatus shown in FIG. In the electron beam heating type vapor deposition apparatus 50 shown in FIG. A cylindrical cooling drum 52 made of metal or the like is disposed in the center of the inside of the vacuum vessel 51 and is rotationally driven by a driving device (not shown). A long film (transparent substrate) 11 is wound around a part of the outer peripheral surface of the cooling drum 52 in the drum circumferential direction, and continuously runs between the uncoiler 53 and the recoiler 54. . A vapor deposition material holding portion 56 is disposed opposite to the film winding portion of the cooling drum 52, and a titanium vapor deposition material 58 constituting a titanium compound to be vapor deposited is accommodated therein. An electron beam generating mechanism (not shown) such as an electron gun is disposed on the side of the vapor deposition material holding unit 56, and an electron beam B is generated from the electron beam generating mechanism. The electron beam B is bent by a magnetic field generated by a magnetic field generating mechanism 60 installed on the opposite side of the vapor deposition material holding unit 56 and irradiated onto the titanium vapor deposition material 58, and the vapor deposition material 58 is heated by the electron beam B. Steam E is emitted toward the cooling drum 2. A partition wall 66 is provided between the cooling drum 52 and the vapor deposition material holding unit 56 to regulate the vapor deposition range. The partition wall 66 has a semi-cylindrical portion 66A that accommodates the cooling drum 52, and a constant space is provided between the inner peripheral surface of the semi-cylindrical portion 66A and the outer peripheral surface of the film winding portion of the cooling drum 52. A gap is formed. In the semi-cylindrical portion 66 </ b> A, a rectangular steam passage port 68 is formed along the axial direction of the cooling drum 52 at a position facing the vapor deposition material holding portion 56. This vapor passage port 68 has the same total length as the deposition width of the film 11.

Further, a nozzle 70 of a gas introduction mechanism (not shown) is disposed on the same side as the electron beam generating mechanism, and a reactive gas is introduced into the vacuum vessel 51 from the nozzle 70. The nozzle 70 may eject gas in a strip shape having a width approximately equal to the deposition width of the film 11, or may have a plurality of ejection ports arranged in a line in the width direction of the film 11. The gas may be ejected all at once. As the reactive _{gas, Ar, Ne, Kr, Xe} , He, H 2, N 2, O 2, 1 or more kinds of gas selected from _{F 2} can be used. The reactive gas G emitted from the nozzle 70 crosses the path of the electron beam B and is set so as to cross the flow path of the titanium metal vapor E emitted from the titanium vapor deposition material 58. By setting the course in this way, the reactive gas G is at least partially ionized by the electron beam B, and comes into contact with and binds to the titanium metal vapor E.

Next, a vapor deposition method using the above apparatus will be described. While reducing the pressure in the vacuum vessel 51, the reactive gas G is ejected from the nozzle 70 at a constant flow rate, and the pressure in the vacuum vessel 51 is balanced at 20 to 800 mPa. When the equilibrium pressure in the vacuum vessel 51 is less than 20 mPa, the reactive gas ion concentration becomes dilute and the reaction efficiency becomes insufficient. When the equilibrium pressure is higher than 800 mPa, the titanium metal vapor E generated from the titanium vapor deposition material 58 is caused by the gas molecules G. The mean free path is shortened and a dense deposited film cannot be formed. Further, since titanium metal vapor E adsorbs various inevitable impurities during vapor deposition, the degree of vacuum is likely to change, resulting in variations in the particle size of vapor deposition particles. Therefore, in order to eliminate the variation in the particle diameter, it is necessary to keep the pressure in the vacuum vessel 51 constant. For that purpose, the partial pressure of moisture in the vapor deposition atmosphere gas is controlled to make the degree of vacuum constant. It is important to keep. The water partial pressure is optimally 2 mPa to 40 mPa (1.5 × 10 ^{−5 to} 3.0 × 10 ⁻⁴ Torr), and if it is out of this range, it is difficult to keep the degree of vacuum constant.

  On the other hand, the electron beam generation mechanism and the magnetic field generation mechanism 60 are operated to irradiate and heat the titanium vapor deposition material 58 with the electron beam B, thereby continuously generating the titanium metal vapor E and from the uncoiler 53 to the recoiler 54. And the film 11 is run. Then, the reactive gas G ejected from the nozzle 70 is ionized in contact with the electron beam B to form a gas flow containing reactive gas ions, and the titanium metal vapor E released radially from the titanium vapor deposition material 58. Contact with. Since the reactive gas ions have high activity and are highly reactive, they immediately combine with the contacted titanium metal vapor E, and the titanium metal vapor E becomes a vapor of the titanium metal compound and is deposited on the film 11 as the titanium oxide layer 22. The transparent laminated film 10 is completed.

  Moreover, FIG. 2 has shown 2nd Embodiment, The transparent laminated film 30 of this 2nd Embodiment is between the transparent base material 11 and the transparent titanium oxide layer 32 formed in the at least one surface. In addition, a relief forming layer 33 is provided to take advantage of the reflection effect of the titanium oxide layer 32. FIG. 2 shows an example of a transparent relief hologram in which a fine uneven relief (for example, a hologram in functional expression) is formed on the surface of the relief forming layer 33. In the relief hologram, interference fringes corresponding to the wavefront of light from an object are formed on the surface of the relief forming layer 33 as a fine uneven relief (pattern). A titanium oxide layer 32 is formed on the surface of the fine unevenness relief (hologram) along the shape of the unevenness pattern. Bright holograms can be observed with optimal brightness and reflectivity.

  As a material of the relief forming layer 33, polyvinyl chloride, acrylic (eg, MMA), styrene, polycarbonate and other thermoplastic resins, unsaturated polyester, melamine, epoxy, polyester (meth) acrylate, urethane (meth) Cured thermosetting resin such as acrylate, epoxy (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, triazine acrylate, or the above thermoplastic resin and heat Mixtures of curable resins can be used.

As a method for forming the relief forming layer 33, a known gravure printing method, roll coating method, three reverse rolls are used, which is obtained by dissolving or dispersing the resin in a solvent as necessary on the transparent substrate 11. With a coating method such as a coating method, the thickness after drying is 0. The resin layer for the relief forming layer 3 is formed by applying and drying to 2 to 10 μm. An uneven relief is attached to the surface of the resin layer to produce a relief forming layer 33. After producing the relief forming layer 3, the layer is formed on the surface using the electron beam heating vapor deposition apparatus 50 shown in FIG. 3 under the same conditions as those formed on the transparent substrate 11 of the first embodiment described above. The thickness is 80 to 120 nm, the average particle size is 10 to 17 nm, the luminance is 42 to 56 cd / m ² , and the reflectance is 17 to 27%. By forming the titanium oxide layer 32, the hologram transparent laminated film 30 having the relief forming layer 33 is completed.

In the electron beam heating vapor deposition apparatus 50 shown in FIG. 3, samples were prepared under the following conditions while changing the degree of vacuum and moisture partial pressure as shown in Table 1.
Film: 25 μm thick, 500 mm wide, PET deposition material: Titanium deposition Thickness: 1000 Å Oxygen introduction pressure: 1 × 10 −1 Pa
Electron beam generation mechanism: Electron impact cathode type self-accelerating electron gun (90 ° deflection)
Acceleration voltage: 30 kV
Emission current: 2A
Scanning width of electron gun: 500mm
Distance between vapor deposition material holding part 56 and film 11: 250 mm
Outer diameter of cooling drum 52: 400 mm
Travel speed of film 11: 10 m / min

Next, the thickness and average particle diameter of the titanium oxide layer of the obtained transparent laminated film, and the brightness, reflectivity, visual condition, and durability of the transparent laminated film were measured.
As for the luminance, Keyence MS-V21 Co., Ltd. was used to measure the luminance in the front direction at the sample center and the sample end.
The reflectance was measured using a Hitachi spectrophotometer 3900H (double monochrome, diffraction grating), and the reflectance at a wavelength of 550 nm was measured.
As for the visual condition, ultraviolet rays were irradiated and visual observation was performed over 60 degrees from the left and right from the front direction in the center of the sample, and ○ was given that there was no glare and it was easy to see and the observation state was good, and x was poor. .
For weather resistance, using the ultraviolet irradiation method defined in JIS-K7350-4, after irradiating ultraviolet rays for 300 hours, the one having no significant change in reflectivity is passed, and the one having changed is Δ, Those markedly changed are indicated by x marks as rejects.
The obtained measurement results are shown in Table 1.

  As can be seen from Table 1, it can be seen that the transparent laminated film of the present invention has an optimum luminance at a high reflectance, a good visual condition, and excellent weather resistance.

On a PET film having a thickness of 25 μm and a width of 500 mm, an ink in which polyvinyl chloride is dissolved is applied by gravure printing so that the thickness after drying is 5 μm, and dried to form a relief forming layer. Furthermore, an uneven relief was formed on the surface. Thereafter, samples were prepared by changing the degree of vacuum and the partial pressure of water as shown in Table 2 under the following conditions using the electron beam heating type vapor deposition apparatus shown in FIG.
Film: 25 μm thick, width 500 mm, PET deposition material: Ti
Deposition film thickness: 1000 Å Oxygen introduction pressure: 1 × 10 −1 Pa
Electron beam generation mechanism: Electron impact cathode type self-accelerating electron gun (90 ° deflection)
Acceleration voltage: 30 kV
Emission current: 2A
Scanning width of electron gun: 500mm
Distance between vapor deposition material holding part 56 and film 11: 250 mm
Outer diameter of cooling drum 52: 400 mm
Travel speed of film 11: 10 m / min

Next, the thickness and average particle diameter of the titanium oxide layer of the obtained transparent laminated film, and the brightness, reflectivity, visual condition, and weather resistance of the transparent laminated film were measured.
As for the luminance, Keyence MS-V21 Co., Ltd. was used to measure the luminance in the front direction at the sample center and the sample end.
The reflectance was measured using a Hitachi spectrophotometer 3900H (double monochrome, diffraction grating), and the reflectance at a wavelength of 550 nm was measured.
As for the visual condition, ultraviolet rays were irradiated and visual observation was performed over 60 degrees from the left and right from the front direction in the center of the sample, and ○ was given that there was no glare and it was easy to see and the observation state was good, and x was poor. .
For weather resistance, using the ultraviolet irradiation method defined in JIS-K7350-4, after irradiating ultraviolet rays for 300 hours, the one having no significant change in reflectivity is passed, and the one having changed is Δ, Those markedly changed are indicated by x marks as rejects.
The obtained measurement results are shown in Table 2.

  As can be seen from Table 2, it can be seen that the transparent laminated film of the present invention has an optimum luminance at a high reflectance, a good visual condition, and excellent durability.

DESCRIPTION OF SYMBOLS 10 Transparent laminated film 11 Transparent base material 12 Titanium oxide layer 30 Transparent laminated film 32 Titanium oxide layer 33 Relief formation layer 50 Electron beam heating type vapor deposition apparatus 51 Vacuum container 52 Cooling drum 53 Uncoiler 54 Recoiler 56 Deposition holding part 58 Deposition material 66 Bulkhead 68 Steam passage 70 Nozzle B Electron beam E Metal vapor G Reactive gas flow

Claims (2)

In a transparent laminated film having a transparent titanium oxide layer formed on at least one surface of a transparent substrate, the transparent titanium oxide layer has a thickness of 80 to 120 nm, an average particle size of 10 to 17 nm, and a luminance of 42~56cd / m ² der is, the transparent laminated film characterized in that is manufactured by using an electron beam heating type deposition apparatus.   The transparent laminated film according to claim 1, wherein a relief forming layer is provided between the transparent substrate and the titanium oxide layer.

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