JP2013182052A - Viewing angle control film, window material using the same, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viewing angle control film superior in productivity, a window material using the same, and a manufacturing method thereof.SOLUTION: A viewing angle control film 100 includes: a light-transmissive resin substrate 1; a first light shielding layer 21 formed on a first surface of the resin substrate 1 and having a cross-sectional shape of wedges arranged at a pitch P1; and a second light shielding layer 22 formed on a second surface of the resin substrate 1 and having a cross-sectional shape of wedges arranged at a pitch P2. Ratios H1/P1 and H2/P2 of heights H1 and H2 of the light shielding layers to the pitches P1 and P2 can be reduced to improve productivity.

Description

  The present invention relates to a viewing angle control film, a window material using the same, and a manufacturing method thereof.

  In recent years, high-rise office buildings, condominiums, and buildings such as hospitals have used window materials provided with a viewing angle control film having a blinding function (privacy) in either the vertical direction or the horizontal direction.

  As such a light-transmitting viewing angle control film, various methods have been proposed, but are roughly classified into two methods. The first method is a louver structure method in which light-shielding louver layers and light-transmitting layers having a rectangular cross section are alternately arranged in parallel. The second method is a wedge structure method in which a trapezoidal wedge structure filled with a light absorbing material and a light transmitting portion are arranged in parallel.

  Patent Documents 1 and 2 relate to a viewing angle control film of a louver structure method. A viewing angle control film of this type is commercially available as a light control film from Sumitomo 3M Limited and as a visual field control film from Shin-Etsu Polymer Co., Ltd.

  FIG. 12 is a cross-sectional view of a main part showing a viewing angle control film of a conventional louver structure system. As shown in FIG. 12, in this viewing angle control film, the louver structure 2 composed of the light absorption layer is formed at the pitch P on the emission surface of the resin base material 1. The louver structure 2 has a rectangular cross section with a width W and a height H.

  Incident light L <b> 1 enters the resin base material 1 from the opening 3 between the adjacent louver structures 2. For example, incident light L1 incident at an incident angle θ1 from the air is refracted on the incident surface of the resin base material 1, and the refracted light L2 passes through the resin base material 1. Since the incident surface and the exit surface of the resin base material 1 are parallel, the refracted light L2 is refracted at the exit angle θ4 (= θ1) on the exit surface of the resin base material 1 and is emitted from the resin base material 1 as the output light L3. Emits into.

FIG. 13 is a graph showing the viewing angle control characteristics (dependence of the total light transmittance η on the light incident angle θ1) of the viewing angle control film of FIG. In FIG. 13, the horizontal axis indicates the light incident angle θ1, and the vertical axis indicates the total light transmittance η. Here, the total light transmittance η is normalized with the value in the front direction (viewing angle θ1 = 0 °) being 1. The example of FIG. 13 is a case where the cutoff angle θ ^* = 30 °.

Here, as shown in FIG. 13, when the relationship between the incident angle θ1 and the cutoff angle θ ^* is θ1> θ ^* or θ1 <−θ ^* , all of the light incident on the opening 3 is the louver structure 2. And cannot be transmitted through the viewing angle control film. This cut-off angle θ ^* can be appropriately set by changing the aspect ratio (height H / pitch P) of the louver structure 2 or the like.

  However, the manufacturing method of the viewing angle control film of the louver structure type has a problem that the production efficiency is extremely low and the cost is high. For example, as disclosed in Patent Document 1, for example, first, a base film in which a louver layer and a light transmission layer are alternately laminated is further stacked, and then a super multi-layer structure is formed by thermocompression bonding or the like. Let it be a block. Next, a single-wafer process is necessary for slicing the block from a predetermined direction and taking out a film-like viewing angle control element in which louver layers and light transmission layers are alternately arranged. Therefore, it is mainly used for small applications such as peep prevention films for personal computers and car navigation systems, and is not particularly suitable for large applications such as window materials for buildings.

  On the other hand, Patent Documents 3 and 4 relate to a wedge-structure viewing angle control film. This type of viewing angle control film is applied to a peep prevention film for personal computers and portable terminals. For example, it is commercially available as an eye barrier from Elecom Corporation.

  FIG. 14 is a cross-sectional view of a main part showing a viewing angle control film of a conventional wedge structure type. As shown in FIG. 14, in this viewing angle control film, wedge structures 20 made of a light absorption layer are formed at a pitch P on the incident surface of the resin base material 1. The wedge structure 20 has a trapezoidal cross section having an upper base W2, a lower base W1, and a height H.

  Incident light L1 enters the resin base material 1 having a refractive index n from the opening 3 between the adjacent wedge structures 20. For example, incident light L <b> 1 incident from the air at an incident angle θ <b> 1 is refracted at a refraction angle θ <b> 2 on the incident surface of the resin substrate 1, and the refracted light L <b> 2 passes through the resin substrate 1. Since the incident surface and the exit surface of the resin substrate 1 are parallel, the refracted light L2 enters the exit surface of the resin substrate 1 at an angle θ3 (= θ2). Here, when the refracted light L2 exits into the air, as shown in FIG. 14, the refracted light L2 is refracted at the exit angle θ4 (= θ1) on the exit surface of the resin substrate 1, and the resin is obtained as the exit light L3. The light is emitted from the substrate 1.

FIG. 15 is a graph showing the viewing angle control characteristics (dependence of the total light transmittance η on the light incident angle θ1) of the viewing angle control film of FIG. In FIG. 15, the horizontal axis represents the light incident angle θ1, and the vertical axis represents the total light transmittance η. Here, the total light transmittance η is normalized with the value in the front direction (viewing angle θ1 = 0 °) being 1. The example of FIG. 15 is a case where the cutoff angle θ ^* = 30 ° and the half value φ = 4.5 ° of the wedge narrow angle.

Here, as shown in FIG. 15, when the relationship between the incident angle θ1 and the cutoff angle θ ^* is θ1> θ ^* or θ1 <−θ ^* , all of the light incident on the opening 3 is It is absorbed by the wedge structure 20 and cannot pass through the viewing angle control film. The cut-off angle θ ^* can be set as appropriate by changing the aspect ratio (height H / pitch P) of the wedge structure 20 and the half value φ of the wedge narrow angle.

  The viewing angle control film of the wedge structure method can be continuously formed by a Roll to Roll method (hereinafter referred to as R2R method) using a mold roll having protrusions for imparting a wedge structure formed on the surface thereof. Therefore, it is possible to continuously produce a wide and long-sized viewing angle control film, which is suitable for large applications such as building window materials. Here, the mold roll is manufactured by engraving a roll having a hard plating layer or the like formed on the surface with a total tool.

JP-T 6-504627 JP 2009-25472 A Special table 2009-524080 JP 2006-171700 A

  However, when the wedge structure aspect ratio H / P exceeds 2.0 and the wedge narrow angle half-value φ is about 5 ° or less, the engraving of the die roll becomes extremely difficult. This is because it becomes difficult to discharge the cutting waste in the engraving process, and the tip of the protrusion formed on the surface of the die roll by the engraving process is bent or missing. Moreover, the lifetime of the obtained mold roll is also reduced.

FIG. 16 is a graph showing the protrusion height H of the mold roll required when the cut-off angle θ ^* is 30 °, 45 °, and 60 ° in the conventional wedge structure method. Table 1 shows the parameter values (pitch P, lower base W1, upper base W2, parameter values related to the wedge structure 20 when the refractive index n of the resin base material 1 and the cut-off angle θ ^* = 30 °, 45 °, and 60 ° Height H, aspect ratio H / P, wedge narrow angle half value φ). In the example shown in FIG. 16 and Table 1, when the offset angle θ ^* = 30 °, the aspect ratio H / P = 2.35, the wedge narrow angle half value φ = 2.92, and the offset angle θ ^* = 45 °. In this case, when the aspect ratio H / P = 1.56 and the wedge narrow angle half value φ = 4.40 and the offset angle θ ^* = 60 °, the aspect ratio H / P = 1.18 and the wedge narrow angle half value φ = When the offset angle θ ^* ≦ 30 °, it becomes difficult to engrave the mold roll.

FIG. 17 is a graph showing the relationship between the cut-off angle θ ^* and the aspect ratio H / P in the conventional wedge structure method. FIG. 18 is a graph showing the relationship between the cutoff angle θ ^* and the half-value angle φ of the wedge narrow angle in the conventional wedge structure method. It can be seen that in order to reduce the offset angle θ ^* (in order to increase the blinding function), it is necessary to increase the aspect ratio H / P and to decrease the half value φ of the wedge narrow angle. Therefore, it becomes difficult to engrave the mold roll.

  Further, even when a desired mold roll is obtained, as the aspect ratio H / P increases, in the process of transferring the shape of the wedge structure to the ultraviolet curable resin or the thermoplastic resin, the occurrence of foam biting, the mold roll Deterioration of the filling property of the resin liquid into the grooves between the protrusions and deterioration of releasability become problems. As a result, there is a problem that the molding speed cannot be increased and the productivity is inferior.

  This invention is made | formed in view of the above, Comprising: It aims at providing the viewing angle control film excellent in productivity, the window material using the same, and its manufacturing method.

One aspect of the present invention is:
A resin substrate having optical transparency;
A first light-shielding layer having a wedge-shaped cross-sectional shape arranged at a pitch P1 on the first surface of the resin substrate;
It is a viewing angle control film provided with the 2nd light shielding layer which has the wedge-shaped cross-sectional shape arranged by pitch P2 on the 2nd surface of the said resin base material. With such a configuration, productivity can be improved.

In the one aspect,
The resin substrate is
A first resin base material on which the first light shielding layer is formed;
A second resin base material on which the second light shielding layer is formed,
A space may be formed between the first resin base material and the second resin base material.

A ratio H1 / P1 of the first light-shielding layer height H1 to the pitch P1;
It is preferable that the ratio H2 / P2 of the height H2 of the second light shielding layer to the pitch P2 is 2.0 or less. With such a configuration, productivity can be reliably improved.

  It is preferable that both the first and second light shielding layers include a light absorbing material. On the other hand, at least one of the first and second light shielding layers may include a light reflecting material. Indoor light can be used effectively. Furthermore, it is preferable that the ratio P2 / P1 of the pitch P2 to the pitch P1 is 4 or more. With such a configuration, generation of moire can be prevented.

  The viewing angle control film can be applied to a window material by attaching a pair of glass plates to the first and second surfaces of the resin base material.

Other aspects of the invention include:
A first groove having a wedge-shaped cross-sectional shape arranged at a pitch P1 by a first mold roll is formed on a first surface of a resin base material having optical transparency. Forming a second groove having a wedge-shaped cross-sectional shape arranged on the surface of 2 at a pitch P2 by a second mold roll;
Filling the first and second grooves with a filler to form a light shielding layer, and a method for producing a viewing angle control film.

  ADVANTAGE OF THE INVENTION According to this invention, the viewing angle control film excellent in productivity, the window material using the same, and its manufacturing method can be provided.

3 is a cross-sectional view of a main part showing a viewing angle control film of a wedge structure method according to Embodiment 1. FIG. It is a graph which shows the viewing angle control characteristic (the dependence with respect to the light incident angle (theta) 1 of the total light transmittance (eta)) of the viewing angle control film 100 of FIG. FIG. 2 is a graph showing a practical cut-off angle θ ^* , a single-side equivalent cut-off angle θ ^*, and a tangential cut-off angle θ ^◇ when η (θ ^* ) = 1/10 with respect to the total light transmittance η in FIG. It is. It is sectional drawing of the laminated glass window material which bonded the glass plates 51 and 52 to the entrance plane and exit surface of the viewing angle control film 100 which concern on Embodiment 1 via the adhesive layers 41 and 42, respectively. 3 is an optical path diagram in the viewing angle control film 100 according to Example 1. FIG. 3 is an optical path diagram in the viewing angle control film 100 according to Example 1. FIG. 3 is an optical path diagram in the viewing angle control film 100 according to Example 1. FIG. It is a typical top view which shows the engraving processing method of a metal mold | die roll. It is an enlarged view which shows the mode of the engraving process by the total type | mold bite in FIG. 6A. It is a figure which shows the method of forming a wedge-shaped groove | channel on both surfaces of the resin base material 1 using ultraviolet curing resin. It is a figure which shows the method of filling a wedge-shaped groove | channel with a filler. It is a figure which shows the thermal transfer molding method of a wedge-shaped groove | channel. It is sectional drawing of the laminated glass window material which bonded the glass plates 51 and 52 to the entrance plane and exit surface of the viewing angle control film 200 which concern on Embodiment 2 via the adhesive layers 41 and 42, respectively. 6 is a cross-sectional view of a main part of a viewing angle control film according to Embodiment 3. FIG. 10 is a cross-sectional view of a main part of a viewing angle control film according to a modification of Embodiment 3. FIG. It is principal part sectional drawing which shows the viewing angle control film of the conventional louver structure system. It is a graph which shows the viewing angle control characteristic (dependence with respect to the light incident angle (theta) 1 of the total light transmittance (eta)) of the viewing angle control film of FIG. It is principal part sectional drawing which shows the viewing angle control film of the conventional wedge structure system. It is a graph which shows the viewing angle control characteristic (the dependence with respect to the light incident angle (theta) 1 of the total light transmittance (eta)) of the viewing angle control film of FIG. It is a graph which shows the protrusion height H of the metal mold | die roll required when cut-off angle (theta) ^* is 30 degrees, 45 degrees, and 60 degrees in the conventional wedge structure system. It is a graph which shows the relationship between cut-off angle (theta) ^* and aspect-ratio H / P in the conventional wedge structure system. It is a graph which shows the relationship between cut-off angle (theta) ^* and half-value angle (phi) of wedge narrow angle in the conventional wedge structure system.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the viewing angle control film of the wedge structure method according to Embodiment 1 will be described with reference to FIG. FIG. 1 is a cross-sectional view of a main part showing a wedge structure type viewing angle control film according to the first embodiment. This viewing angle control film is suitable for window material use, for example.

  As shown in FIG. 1, the viewing angle control film 100 of the wedge structure method according to the first embodiment includes a wedge structure (light shielding layer) 21 arranged on the incident surface of the resin base material 1, and the resin base material 1. And a wedge structure (light-shielding layer) 22 arranged on the exit surface. Both wedge structures 21 and 22 are made of a light absorbing layer. The wedge structure 21 has a trapezoidal cross section having an upper base W21, a lower base W11, and a height H1, and is arranged at a pitch P1. The wedge structure 22 has a trapezoidal cross section with an upper base W22, a lower base W12, and a height H2, and is arranged at a pitch P2. The wedge narrow angle half of the wedge structure 21 is φ1, and the wedge narrow angle half value of the wedge structure 22 is φ2. In addition, the wedge structure 21 and the wedge structure 22 face each other at a distance T in a direction perpendicular to the main surface of the viewing angle control film 100.

  Incident light L <b> 1 enters the resin base material 1 from the opening 31 between the adjacent wedge structures 21. For example, incident light L <b> 1 incident from the air at an incident angle θ <b> 1 is refracted at a refraction angle θ <b> 2 on the incident surface of the resin base material 1, and the refracted light L <b> 2 passes through the resin base material 1. Since the incident surface and the exit surface of the resin substrate 1 are parallel, the refracted light L2 enters the exit surface of the resin substrate 1 at an angle θ3 (= θ2). Here, when the refracted light L2 is emitted into the air, the refracted light L2 is refracted at the emission angle θ4 (= θ1) on the emission surface of the resin substrate 1, as shown in FIG. And it radiate | emits as the emitted light L3 from the opening part 32 between the wedge structures 22 adjacent.

Next, with reference to FIG. 1, the blinding function by the wedge structures 21 and 22 in the viewing angle control film 100 according to the present embodiment will be described.
First, the blindfold function by only the wedge structure 21 arranged on the incident surface of the resin base material 1 will be described. This is the same as the blinding function by the wedge structure 20 in the viewing angle control film of the conventional wedge structure system shown in FIG.

As described above, the wedge structure 21 having a trapezoidal cross section having a wedge narrow angle half value φ1, a lower base W11, an upper base W21, and a height H1 is disposed on the resin base material 1 having a refractive index n at a pitch P1. . In this case, when the cut-off angle θ ^{* 1 at} which the total light transmittance η is completely “0” is derived from Snell's law and geometrical relationship, the following equation (1) is obtained.
θ ^{* 1} = sin ^-1 <n · sin [tan ^-1 {(P1-W11) / H1 + tanφ1}]> (1)
tanφ1 = (W11-W21) / 2 / H1

Here, assuming that the light incident angle to the viewing angle control film 100 is θ1 and the refraction angle after being incident on the resin substrate 1 is θ2, the total light transmittance η is a linear function of θ1 as shown in the following equation (2). Become.
η (θ1) = 1-H1 ・ (tanθ2-tanφ1) / (P1-W11) (However, θ2> φ1) (2)
η = 1 (However, θ2 ≦ φ1)
θ2 = sin ^-1 (1 / n ・ sinθ1)
-90 ° ≦ θ1 ≦ 90 °

Next, the blinding function by only the wedge structure 22 arranged on the emission surface of the resin base material 1 will be described. A wedge structure 22 having a trapezoidal cross section with a half-width φ2 of a wedge narrow angle, a lower base W12, an upper base W22, and a height H2 is disposed on the resin base material 1 having a refractive index n at a pitch P2. In this case, similarly to the wedge structure 21, when the cut-off angle θ ^{* 2 at} which the total light transmittance η is completely “0” is derived from Snell's law and geometrical relationship, the following equation (3) is obtained. It is done.
θ ^{* 2} = sin ^-1 <n · sin [tan ^-1 {(P2-W12) / H2 + tanφ2}]> (3)
tanφ2 = (W12-W22) / 2 / H2

Here, when the light incident angle to the window material is θ1 and the refraction angle after incident on the resin base material 1 is θ2, the total light transmittance η is a linear function of θ1 as shown in the following equation (4).
η (θ1) = 1-H2 ・ (tanθ2-tanφ2) / (P2-W12) (However, θ2> φ2) (4)
η = 1 (However, θ2 ≦ φ2)
θ2 = sin ^-1 (1 / n ・ sinθ1)
-90 ° ≦ θ1 ≦ 90 °

The concept according to the embodiment of the present invention will be described below based on the equations (1) to (4).
In the viewing angle control film 100 of the wedge structure type according to the first embodiment, the wedge structure 21 having the cut-off angle θ ^{* 1} as the independent viewing angle controllability is arranged on the incident surface, and the viewing angle control alone is performed. As a characteristic, a wedge structure 22 having a cut-off angle θ ^{* 2} (where θ ^{* 1} ≧ θ ^{* 2} > 0 °) is arranged on the exit surface. That is, the conventional viewing angle control film has a single-sided wedge structure, whereas the viewing angle control film 100 according to Embodiment 1 has a double-sided wedge structure.

  FIG. 2 is a graph showing the viewing angle control characteristics (dependence of the total light transmittance η on the light incident angle θ1) of the viewing angle control film 100 of FIG. In FIG. 2, the horizontal axis represents the light incident angle θ1, and the vertical axis represents the total light transmittance η. Here, the total light transmittance η is normalized with the value in the front direction (viewing angle θ1 = 0 °) being 1.

  As shown in FIG. 2, the total light transmittance η of the viewing angle control film 100 according to the present embodiment is a product obtained by multiplying the individual light transmittances η1 and η2 of the wedge structures 21 and 22 by each other. It becomes. That is, the total light transmittance η of the viewing angle control film according to the present embodiment is a quadratic function of the incident angle θ1.

Here, the example of FIG. 2 is a case where the cut-off angle θ ^{* 1} = 60 ° of the wedge structure 21 alone and the cut-off angle θ ^{* 2} = 50 ° of the wedge structure 22 alone. As is clear from FIG. 2, the cutoff angle θ ^{* at which} the total light transmittance η of the viewing angle control film 100 according to the present embodiment is completely “0” is the cutoff angle ( θ ^{* 2} = 50 °), the total light transmittance η gradually decreases as the incident angle θ1 approaches ± θ ^{* 2} from 0 °, and becomes completely “0” at θ1 = ± θ ^{* 2} .

Table 2 shows parameter values relating to the wedge structure 21 in the example of FIG. 2 (cut-off angle θ ^{* 1} , pitch P1, lower base W11, upper base W21, height H1, aspect ratio H1 / P1, half value φ1 of the wedge narrow angle. ) And parameter values related to the wedge structure 22 (cutoff angle θ ^{* 2} , pitch P2, lower base W12, upper base W22, height H2, aspect ratio H2 / P2, half value φ2 of wedge narrow angle). Further, the refractive index n of the resin base material 1 is 1.52.

Next, a practical cut-off angle (hereinafter referred to as a practical cut-off angle) θ ^★ when applied as a window material will be considered. The practical cut-off angle θ ^* visually recognized by the observer is about 1/20 to 1/10 of the total light transmittance η (0) = 1 in the front view (center of view: incident angle θ1 = 0 °). You may judge that it is the value of incident angle (theta) 1 used as a total light transmittance.
In the viewing angle control film 100 according to the present embodiment, the practical cut-off θ ^★ when the combination of the cut-off angles θ ^{* 1} and θ ^{* 2} of the wedge structures 21 and 22 is changed in the range of 30 ° to 60 °. Asked. Here, among the parameters shown in Table 2, the cut-off angles θ ^{* 1} and θ ^{* 2} were changed by changing H1 and H2. The aspect ratios H1 / P1 and H2 / P2 and the half-values φ1 and φ2 of the wedge narrow angle change due to the dependent functions of H1 and H2, respectively, but other parameters remain as in Table 2.

Table 3 shows the practical cut-off angle θ ^* when η (θ ^* ) = 1/20.

Table 4 shows the practical cut-off angle θ ^* when η (θ ^* ) = 1/10. FIG. 3 shows a practical cut-off angle θ ^* when η (θ ^* ) = 1/10 with respect to the total light transmittance η in FIG.

Next, the coordinate point P _AL (−θ ^* , 0.05) and the coordinate point P _BL (−φ2, 1) (or the coordinate point P _AR (θ ^* , 0.05) and the coordinate point P in the graph of FIG. The value of the horizontal axis intercept where the straight line passing through _BR (φ2, 1)) intersects the horizontal axis (η = 0) may be considered to correspond to the cutoff angle of the conventional single-sided wedge structure method shown in FIG. . This is called the one-side equivalent cut-off angle θ ^☆ .
In the viewing angle control film 100 according to the present embodiment, the one-side equivalent cut-off angle θ when the combination of the cut-off angles θ ^{* 1} and θ ^{* 2} of the wedge structures 21 and 22 is changed in the range of 30 ° to 60 °. I asked for ^☆ .

Table 5 shows the one-side equivalent cut-off angle θ ^☆ when the practical cut-off angle θ ^{★ is obtained} by η (θ ^★ ) = 1/20.

Table 6 shows the one-side equivalent cut-off angle θ ^☆ when the practical cut-off angle θ ^{★ is obtained} by η (θ ^★ ) = 1/10. FIG. 3 shows the one-side equivalent cut-off angle θ ^☆ when the practical cut-off angle θ ^* is η (θ ^* ) = 1/10 with respect to the total light transmittance η of FIG.

Further, the value of the horizontal axis intercept at which the tangent at the coordinate point P _CL (−φ2, 1) (or the coordinate point P _CR (φ2, 1)) of the above-mentioned quadratic function intersects the horizontal axis (η = 0). Is called the tangential cutoff angle θ ^◇ .
In the viewing angle control film 100 of the present embodiment, the tangent cutoff angle when changing the cut-off angle theta ^{* 1} wedge structure ^21, a combination of theta ^{* 2} a in the range of 30 ° ~60 ° θ ^◇ Asked.

Table 7 shows the tangential cut-off angle θ ^◇. Note that the tangential cutoff angle θ ^◇ is the same value when the practical cutoff angle θ ^{★ is obtained} by η (θ ^★ ) = 1/20 and when η (θ ^★ ) = 1/10 is obtained. .

Further, in FIG. 3, with respect to η total light transmittance of the Figure 2 shows a tangential cutoff angle theta ^◇. As shown in FIG. 3, the total light transmittance η of the viewing angle control film 100 according to the present embodiment is the tangent that gives the tangential cutoff angle θ ^◇ and the cutoff angle θ ^{* 2} (θ ^{* 1} ≧ θ ^{*). 2} > 0) and the total light transmittance η2 by the wedge structure 22 alone.

  Further, as shown in Tables 3 and 4, according to the double-sided wedge structure method combined with the low aspect ratio wedge structure according to the present embodiment, compared with the conventional single-sided wedge structure method shown in FIG. It is possible to narrow the field of view by 20 ° (total 20 ° in the left-right direction). Therefore, it is possible to manufacture a window material having a very narrow field of view with a viewing angle of about ± 20 ° (40 ° in total in the left-right direction), which is difficult to manufacture with the conventional single-sided wedge structure method.

  Next, the aspect ratio H / P which is a problem in both engraving of the mold roll and forming the wedge structure on the viewing angle control film will be examined. As described above, when the width of the mold roll exceeds 1 m as in the window material application, the larger the aspect ratio H / P value is, and the smaller the narrow angle 2φ of the wedge structure is, the more the cutting waste in engraving processing is. Is difficult to discharge, and the tip of the projection is bent or missing. For this reason, it is necessary to slow down the processing speed, and the processing time also takes a long time. In other words, the smaller the aspect ratio H / P, the better in order to engrave the mold roll over the entire width with high accuracy.

In the viewing angle control film 100 according to the present embodiment, the combination of the cut-off angles θ ^{* 1} and θ ^{* 2} of the wedge structures 21 and 22 was changed within a range of 30 ° to 60 ° as θ ^{* 1} = θ ^{* 2} . In this case, the cut-off angle θ ^* corresponding to one side was obtained, and the aspect ratio H / P in the single-sided wedge structure method corresponding to this was obtained.

Table 8 shows the single-sided equivalent cut-off angle θ ^☆ when the practical cut-off angle θ ^{★ is obtained} by η (θ ^★ ) = 1/20, and the corresponding aspect ratio H / P is shown. Specifically, the cut-off angle θ ^{* 1} = θ ^{* 2} of the wedge structures 21 and 22 at the uppermost stage of the table, the aspect ratio H / P (1) of the wedge structures 21 and 22 at the second stage, and the third stage. one side corresponding cut-off angle theta ^☆, the aspect ratio of the single-sided wedge structure scheme corresponding to the one side corresponds cutoff angle theta ^☆ the fourth stage H / P (2), aspect ratio 5 stage (lowermost stage) H / P The ratio (%) of aspect ratio H / P (1) to (2) is shown.

In Table 9, as in Table 8, a single-sided wedge structure method corresponding to a single-sided cut-off angle θ ^☆ obtained when the practical cut-off angle θ ^{★ is obtained} by η (θ ^* ) = 1/10 is obtained. The aspect ratio H / P is shown.

As shown in Tables 8 and 9, in the double-sided wedge structure method according to the present embodiment, the aspect ratio H / P (2) necessary to obtain the same practical cut-off angle θ ^* as in the conventional single-sided wedge structure method. As compared with the above, the aspect ratio H / P (1) can be greatly reduced. Specifically, when the practical cut-off angle θ ^{* is obtained} by η (θ ^* ) = 1/20, the aspect ratio H / P (1) is 82.5 of the aspect ratio H / P (2) on average. %. Further, when the practical cut-off angle θ ^{* is obtained} by η (θ ^* ) = 1/10, the aspect ratio H / P (1) is 76.9% of the aspect ratio H / P (2) on average. It was.

  In the double-sided wedge structure method according to the present embodiment, the occurrence of moire can be a problem depending on the combination of the pitch ratio P2 / P1, the light shielding width ratios W11 / P1, W12 / P2, and the distance T.

  In order to prevent the occurrence of moire, the pitch P1 (<pitch P2) may be set to 50 μm or less, preferably 30 μm or less, and the pitch ratio may be set to P2 / P1 of 4, preferably 6 or more. Thereby, the moire is hardly visually recognized by the observer. Furthermore, it is preferable that the light shielding width ratios W11 / P1 and W12 / P2 are both 0.3 or less.

  In addition, as in Embodiment 2 described later, if two single-sided wedge structure type viewing angle control films are arranged to face each other through an air layer, the pitch ratio P2 / P1 is 4 or less, Generation of moire can be prevented by declining the wedge structure rows so that they are not parallel to each other.

[Example 1]
Next, a specific example according to the first embodiment will be described with reference to FIG.
FIG. 4 is a cross-sectional view of a laminated glass window material in which glass plates 51 and 52 are bonded to the entrance surface and the exit surface of the viewing angle control film 100 according to Embodiment 1 via adhesive layers 41 and 42, respectively.
Table 10 shows the parameters (cut-off angles θ ^{* 1} , θ ^{* 2} , pitches P1, P2, aperture ratio (light transmission width ratio) to incident light) of the wedge structures 21 and 22 on the incident side and the emission side in this example. ε1, ε2, lower base W11, W12, upper base W21, W22, height H1, H2, aspect ratio H1 / P1, H2 / P2, half value of wedge narrow angle φ1, φ2) and other conditions (resin substrate 1 Is the refractive index n, the distance T between the wedge structures 21 and 22, the thickness t of the adhesive layers 41 and 42, and the total thickness ΣT (= H1 + T + H2 + t) of the light transmission portion.

  5A to 5C are optical path diagrams in the viewing angle control film 100 according to the first embodiment. 5A to 5C show the case where the light incident position is the left end of the opening 31, the light incident position is the center of the opening 31, and the light incident position is the right end of the opening 31, respectively.

Next, a method for manufacturing the viewing angle control film 100 according to Example 1 will be described.
First, with reference to FIG. 6A and 6B, the engraving process method of the seamless metal mold | die roll used for shaping | molding of a wedge structure is demonstrated. FIG. 6A is a schematic plan view showing a mold roll engraving method. FIG. 6B is an enlarged view showing a state of engraving processing using the total-type tool in FIG. 6A.

  As shown in FIG. 6A, the mold roll 60 is placed on a roll lathe 61, and lathe machining is performed using a total tool 63. A bite chip 63 a is provided at the tip of the total type bit 63. The total type tool 63 is placed on the tool table 62. The tool table 62 is placed on a guide 64 that extends in the horizontal direction of the drawing. Therefore, the total bite 63 can slide in the horizontal direction of the drawing. Further, the total bite 63 can slide in the vertical direction of the drawing.

  As shown in FIG. 6B, a hard plating layer 60 a made of copper or nickel, which is a free-cutting metal material, is formed on the surface of the mold roll 60. The bite chip 63 a provided at the tip of the total type bite 63 has a shape corresponding to the shape of the light transmission part of the viewing angle control film 100. Thereby, the protrusion 60b which has the same dimension and the same pitch as the wedge structure formed in the viewing angle control film 100 on the surface of the mold roll 60 is formed.

  Next, a method of forming wedge-shaped grooves on both surfaces of the resin base material 1 of FIG. 1 using the mold roll 60 will be described with reference to FIG. FIG. 7 is a diagram illustrating a method of forming wedge-shaped grooves on both surfaces of the resin base material 1 using an ultraviolet curable resin. As shown in FIG. 7, an ultraviolet curable resin is applied on one surface of the transparent substrate film F <b> 1 by a coat die 71. What is necessary is just to use what consists of general purpose PET, PC, p-MMA etc. as the transparent base film F1. Moreover, as a transparent ultraviolet curable resin applied to the transparent base film F1, a general-purpose and inexpensive resin having a refractive index n = 1.49 to 1.56 may be used.

  Next, the applied ultraviolet curable resin is pressed against the mold roll R2 by the pressing roll R1, and the wedge shape is transferred to the applied ultraviolet curable resin. Then, while the wedge shape is transferred by the mold roll R2, ultraviolet rays are irradiated by the UV lamp UV1 through the transparent base film F1 to cure the ultraviolet curable resin. Thereafter, release is performed using a release roll R3. Thereby, as shown in << α section sectional view >> of FIG. 7, a resin layer having a wedge-shaped groove on one surface of the transparent base film F1 is formed.

  Furthermore, by using the rolls R4 and R5, the other surface of the transparent base film F1 is set to the upper side, and an ultraviolet curable resin is coated on the other surface by the coat die 72. Next, the applied ultraviolet curable resin is pressed against the mold roll R7 by the pressing roll R6, and the wedge shape is transferred to the applied ultraviolet curable resin. Then, while the wedge shape is transferred by the mold roll R7, ultraviolet rays are irradiated by the UV lamp UV2 through the transparent base film F1 to cure the ultraviolet curable resin. Thereafter, release is performed using a release roll R8. As a result, as shown in << β section sectional view >> of FIG. 7, an original film F2 in which resin layers having wedge-shaped grooves are formed on both surfaces of the transparent base film F1 is obtained. This raw film F2 corresponds to the resin substrate 1 of FIG.

  Instead of transferring the groove shape on both front and back surfaces in one pass as shown in FIG. 7, in the first pass, the groove shape is transferred to only one surface of the transparent substrate film F1 and then rewound, and then the second pass. Then, a two-pass molding process may be used in which the groove shape is transferred to the opposite surface.

  Next, with reference to FIG. 8, a method for filling a wedge-shaped groove of the raw film F2 with a filler will be described. FIG. 8 is a diagram illustrating a method of filling a wedge-shaped groove with a filler. Initially, the raw fabric film F2 has a cross section as shown in the << a section sectional view >> of FIG. As shown in FIG. 8, a liquid filler is applied over one side of the original film F2 using, for example, a comma roll R9. As a result, as shown in FIG. 8B sectional view, the entire surface of the original film F2 (the flat portion on the surface and the wedge-shaped groove) is covered with the filler.

  Thereafter, for example, the rubber blade 81 is used to scrape off the excess filler on the raw film F2. As a result, as shown in the << c section sectional view >> of FIG. 8, the filler covering the flat portion of the surface of the raw film F2 is removed, and only the wedge-shaped groove is filled with the filler. And after drying a filler, the original fabric film F2 is wound up. Thereby, a wedge structure can be formed on one side of the raw film F2. The same applies to the opposite surface. As the filler, a solvent-based coating liquid or an ultraviolet curable resin liquid containing carbon black, titanium black or the like can be used.

  Since the viewing angle control film 100 according to the present embodiment does not require the collimating function described in Patent Documents 1 and 2, the refractive index of the solvent of the filler constituting the wedge structures 21 and 22 is that of the light transmitting portion. There is no problem even if the refractive index is the same as the refractive index or a material having a high refractive index.

[Example 2]
In the second embodiment, the parameters of the wedge structure 22 on the emission side in the first embodiment are changed as shown in Table 11. In this example, since the aspect ratio of the wedge structure 22 is small and close to 1 as compared to Example 1, a thermoplastic resin film such as p-MMA or PC was used, and a wedge-shaped groove was heat transfer molded by the R2R method. The rest is the same as in the first embodiment.

  With reference to FIG. 9, the thermal transfer molding method of the wedge-shaped groove will be described. FIG. 9 is a diagram showing a thermal transfer molding method of a wedge-shaped groove. As shown in FIG. 9, the upper and lower surface layers of a transparent base film F11 made of a thermoplastic resin are preheated by a preheater 91 such as a halogen heater. Initially, the transparent base film F11 has a rectangular cross section as shown in the << d-part cross-sectional view >> of FIG.

  Thereafter, the preheated transparent base film F11 is passed between the mold roll R10 and the backup roll R11 whose surface temperature is heated to Tg of the material resin of the transparent base film F11. As a result, as shown in the << e section sectional view >> of FIG. 9, a wedge-shaped groove is thermally transferred to one surface of the transparent base film F1. Then, by blowing cool air from the blower 92, the transparent base film F11 on which the wedge-shaped grooves are thermally transferred is cooled. The same applies to the opposite surface.

<Embodiment 2>
Next, a viewing angle control film 200 according to Embodiment 2 will be described with reference to FIG. FIG. 10 is a cross-sectional view of a laminated glass window material in which glass plates 51 and 52 are bonded to the entrance surface and the exit surface of the viewing angle control film 200 according to Embodiment 2 via adhesive layers 41 and 42, respectively.

  The viewing angle control film 100 according to the first embodiment is composed of one resin base material 1 having wedge structures 21 and 22 formed on both sides, whereas the viewing angle control film according to the second embodiment. 200 is composed of two resin base materials 11 and 12 each having a wedge structure formed on only one surface. Specifically, the resin base material 11 in which the wedge structure 21 is formed on one side and the resin base material 12 in which the wedge structure 22 is formed on one side are not formed with the wedge structure via the air layer 13. It arrange | positions so that surfaces may oppose. With such a configuration, the same effect as in the first embodiment can be obtained. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

<Embodiment 3>
Next, the viewing angle control film 300 according to Embodiment 3 will be described with reference to FIGS. 11A and 11B. FIG. 11A is a cross-sectional view of main parts of a viewing angle control film according to Embodiment 3. FIG. 11B is a cross-sectional view of main parts of a viewing angle control film according to a modification of Embodiment 3.

  In the viewing angle control film 100 according to the first embodiment shown in FIG. 1, the wedge structures 21 and 22 are both composed of a black light absorption layer, whereas according to the third embodiment shown in FIG. 11A. In the viewing angle control film 300, the wedge structure 21 on the incident side (inside the room) is composed of a white light reflecting layer. In the viewing angle control film 300 according to the modification of Embodiment 3 shown in FIG. 11B, the wedge structure 22 on the emission side (outdoor side) is also composed of a white light reflecting layer.

  The viewing angle control film 300 according to the third embodiment has a merit that the reflected light of the room light can be used effectively at night, for example, having the same blindfold function as the first and second embodiments. ing. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

As described above, according to the embodiment of the present invention, the wedge structures 21 and 22 having relatively low aspect ratios H / P (≦ 2.0) are provided on the entrance surface and the exit surface, respectively. Due to this, the viewing angle has a wide range of blinding functions from about 120 ° (for example, a combination of θ ^{* 1} = θ ^{* 2} = 90 °) to about 40 ° (for example, a combination of θ ^{* 1} = θ ^{* 2} = 30 °). A viewing angle control film can be obtained. In addition, since the aspect ratio H / P can be reduced, the mold roll can be easily manufactured and shaped. As a result, productivity can be improved.

1, 11, 12 Resin base material 13 Air layer 21, 22 Wedge structure 31, 32 Opening 41, 42 Adhesive layer 51, 52 Glass plate 60 Mold roll 60a Hard plating layer 60b Protrusion 61 Roll lathe 62 Bite base 63 Total type Bite 63a Bite chip 64 Guide 71, 72 Coat die 81 Rubber blade 91 Preheater 92 Blower 100, 200, 300 Viewing angle control film F1, F11 Transparent substrate film F2 Original film R1, R6 Press roll R2, R7, R10 Mold Roll R3, R8 Release roll R4, R5 Roll R9 Comma roll R11 Backup roll UV1, UV2 UV lamp

Claims (8)

A resin substrate having optical transparency;
A first light-shielding layer having a wedge-shaped cross-sectional shape arranged at a pitch P1 on the first surface of the resin substrate;
A viewing angle control film comprising: a second light shielding layer having a wedge-shaped cross-sectional shape arranged at a pitch P2 on the second surface of the resin base material. The resin substrate is
A first resin base material on which the first light shielding layer is formed;
A second resin base material on which the second light shielding layer is formed,
The viewing angle control film according to claim 1, wherein a space is formed between the first resin base material and the second resin base material. A value of a ratio H1 / P1 of the height H1 of the first light shielding layer to the pitch P1, and
The viewing angle control film according to claim 1 or 2, wherein the ratio H2 / P2 of the height H2 of the second light shielding layer to the pitch P2 is 2.0 or less.   The viewing angle control film according to any one of claims 1 to 3, wherein each of the first and second light shielding layers contains a light absorbing material.   The viewing angle control film according to any one of claims 1 to 3, wherein at least one of the first and second light shielding layers includes a light reflecting material.   The viewing angle control film according to any one of claims 1 to 5, wherein a ratio P2 / P1 of the pitch P2 to the pitch P1 is 4 or more. The viewing angle control film according to any one of claims 1 to 6,
A window material comprising a pair of glass plates attached to the first and second surfaces of the resin base material. A first groove having a wedge-shaped cross-sectional shape arranged at a pitch P1 by a first mold roll is formed on a first surface of a resin base material having optical transparency. Forming a second groove having a wedge-shaped cross-sectional shape arranged on the surface of 2 at a pitch P2 by a second mold roll;
Filling the first and second grooves with a filler to form a light shielding layer, and a method for producing a viewing angle control film.

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