JP2019191259A - Viewing angle control sheet - Google Patents

Abstract

To provide a viewing angle control sheet which has good balance between hardness of a surface and toughness of the inside, and hardly causes whitening and deformation.SOLUTION: A viewing angle control sheet includes a louver layer 1 in which a light transmission strip 2 and a light-shielding strip 3 are alternately provided and a protective layer 4 which is provided on one surface of a louver layer and whose at least a part is transparent, in which at least one of the light transmission strip and the light-shielding strip is formed of silicone rubber, the protective layer has a multilayer structure including two or more resin layers, a first resin layer constituting a surface at an opposite side to the louver layer in the multilayer structure is formed of a (meth)acrylic resin, a second resin layer constituting the rear face at a louver layer side in the multilayer structure is formed of polycarbonate, and a thickness of the first resin layer is thinner than a thickness of the second resin layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a viewing angle control sheet capable of controlling a viewing angle when installed on an illumination, an information display screen or the like.

  Patent Document 1 discloses a light transmission direction control sheet that can be used as a viewing angle control sheet. The light transmission direction control sheet includes a louver layer that is a main body that controls a viewing angle, in which light transmission bands and light shielding bands are alternately arranged, and a transparent resin layer that is attached to both surfaces of the louver layer. Since the refractive index difference between the transparent resin layer and the louver layer is adjusted within a predetermined range, the light transmittance is high. For this reason, it is possible to obtain a sufficiently bright display screen even when the luminance of the backlight of the information display device provided with the sheet is suppressed and the backlight luminance is set low.

JP 2017-146359 A

When the viewing angle control sheet is installed at a place where a person touches such as a touch panel or a switch, it is necessary to install protective layers on both sides of the louver layer in order to protect the silicone rubber louver layer. On the other hand, the transparent resin layer of Patent Document 1 can function as a protective layer, but is not necessarily satisfactory in terms of rigidity, hardness, heat resistance, decomposition resistance, and the like.
When the present inventors examined specifically, there existed the following problem. If the protective layer is made of silicone, the rigidity and hardness are insufficient, and further, since it has tackiness, dirt is likely to adhere. If the protective layer is made of polyethylene terephthalate, the heat resistance is insufficient, and there is a concern that the protective layer will be deformed in the summer. When the protective layer is made of polycarbonate, the decomposition resistance is insufficient, and there is a concern of whitening due to hydrolysis in the indoor of summer, and the hardness of the surface is insufficient, resulting in dents or scratches. When the protective layer is made of an acrylic resin, there are problems of brittleness that breaks without following the deformation of the louver layer and low adhesion to the louver layer.

  The present invention provides a viewing angle control sheet that has a good balance between surface hardness and internal toughness and is less prone to whitening and deformation.

[1] A louver layer in which a light transmission band and a light shielding band are alternately and repeatedly provided, and a protective layer that is provided on one surface of the louver layer and is at least partially transparent. At least one of the belt and the light-shielding belt is formed of silicone rubber, the protective layer has a multilayer structure composed of two or more resin layers, and the surface of the multilayer structure opposite to the louver layer The first resin layer constituting the first resin layer is formed of (meth) acrylic resin, and the second resin layer constituting the back surface on the louver layer side of the multilayer structure is formed of polycarbonate. The viewing angle control sheet is thinner than the second resin layer.
[2] The viewing angle control sheet according to [1], wherein the first resin layer has a thickness of 1 μm to 200 μm, and the second resin layer has a thickness of 800 μm to 1200 μm.
[3] The viewing angle control sheet according to [1] or [2], wherein an adhesive layer is provided between the louver layer and the protective layer, and the adhesive layer is formed of silicone rubber.
[4] The viewing angle control sheet according to any one of [1] to [3], wherein a base layer that is at least partially transparent is provided on the other surface of the louver layer.

  The viewing angle control sheet of the present invention has a good balance between surface hardness and internal toughness, and is less likely to be whitened or deformed. Suitable for installation in.

It is a perspective view which shows an example of the viewing angle control sheet which concerns on this invention. It is sectional drawing which follows the II-II line | wire in FIG. It is a perspective view which shows another example of the viewing angle control sheet which concerns on this invention.

  The viewing angle control sheet of the present invention includes a louver layer in which a light transmission band and a light shielding band are alternately and repeatedly provided, at least one surface of the louver layer, and at least a part of the protective layer being transparent. . At least one of the light transmission band and the light shielding band is formed of silicone rubber. The protective layer has a multilayer structure composed of two or more resin layers. The 1st resin layer which comprises the surface on the opposite side to the said louver layer among the said multilayer structures is formed with the (meth) acrylic-type resin. Of the multilayer structure, the second resin layer constituting the back surface on the louver layer side is formed of polycarbonate. The first resin layer is thinner than the second resin layer.

  Hereinafter, specific description will be given with reference to the drawings, but the dimensions of the drawings are different from actual ones for convenience of description. In the present specification, the numerical range of “lower limit value to upper limit value” means a numerical range of “more than the lower limit value and less than the upper limit value” unless otherwise specified. Further, in this specification, the “thickness” is a value obtained by observing a cross section of a measurement object using a magnifying observation means such as a digital microscope, measuring the thicknesses at five locations, and averaging them.

≪Viewing angle control sheet 10≫
As shown in FIGS. 1 and 2, the viewing angle control sheet 10 according to the first embodiment of the present invention includes a louver layer 1 in which light transmission bands 2 and light shielding bands 3 are alternately provided, and a louver layer 1. And a base layer 5 provided on the second surface of the louver layer 1. The first surface and the second surface of the louver layer 1 are surfaces facing each other.

  In the plane perpendicular to the Z direction, the thickness direction of the viewing angle control sheet 10 is perpendicular to the X direction, and the direction in which the light transmission band 2 and the light shielding band 3 extend is perpendicular to both the X direction and the Z direction. This direction is the Y direction. The light transmission band 2 and the light shielding band 3 constituting the louver layer 1 are both strips extending in the X direction, and a plurality of light transmission bands 2 and a plurality of light shielding bands 3 are alternately arranged in the Y direction. . The width in the Y direction of the plurality of light transmission bands 2 is uniform and constant in the X direction. The width in the Y direction of the plurality of light shielding bands 3 is also uniform and constant in the X direction.

  The size of the viewing angle control sheet 10 is not particularly limited, and examples thereof include a rectangular size having a length of 10 mm to 100 cm and a width of about 10 mm to 100 cm in plan view. The thickness of the viewing angle control sheet 10 can be, for example, about 500 μm to 5 mm, including the protective layer 4, the louver layer 1, and the base layer 5.

  Each light transmission band 2 and each light shielding band 3 of the louver layer 1 are band-shaped portions penetrating in the thickness direction (Z direction) of the louver layer 1. In the louver layer 1, light is transmitted along the thickness direction of the louver layer 1, that is, the thickness direction of the viewing angle control sheet 10 through the light transmission band 2 sandwiched between the light shielding bands 3. 2 represents the range of viewing angles through which light can be transmitted.

At least one of the light transmission band 2 and the light shielding band 3 is made of silicone rubber. Silicone rubber is excellent as an optical member because it is excellent in heat resistance, chemical resistance, decomposition resistance, transparency, flexibility and the like.
From the viewpoint of improving the adhesiveness of the light shielding band 3 to the light transmission band 2, the light shielding band 3 is preferably made of silicone rubber like the light transmission band 2.

The protective layer 4 provided on the first surface (one surface) of the louver layer 1 only needs to be at least partially transparent, and may be opaque by providing printing or decoration on the other portion.
The base layer 5 provided on the second surface (the other surface) of the louver layer 1 is an arbitrary layer. The base layer 5 may be at least partially transparent, and may be opaque by providing printing or decoration on the other part.
It is preferable that the light transmittance of the transparent portion of the protective layer 4 and the transparent portion of the base layer 5 is independently the same as the light transmission band of the louver layer 1. Specifically, the light transmittance (light transmittance) when light is transmitted in the thickness direction of the protective layer 4 or the base layer 5 only to the transparent portion of the protective layer 4 or the base layer 5 is 75 to 99.99. 99% is preferred.

[Protective layer 4]
The protective layer 4 has a multilayer structure composed of two or more resin layers laminated in the Z direction (not shown). The multilayer structure may be two or more layers, may be three layers or more, and may be four to ten layers. However, when the number of layers is increased, the light transmittance may be lowered due to interface reflection between layers. Therefore, 2 to 4 layers are preferable, 2 to 3 layers are more preferable, and 2 layers are more preferable.
The number of layers of the protective layer 4 is determined by counting the number of layers of the section cut in the thickness direction of the viewing angle control sheet 10 using a magnification observation means such as a digital microscope.
The surface of the protective layer 4 may be subjected to known surface treatments in the field of resin molded products such as antireflection treatment (AR treatment) and antiglare treatment (AG treatment).

  Of the multilayer structure of the protective layer 4, the resin layer constituting the surface opposite to the louver layer 1 is referred to as a first resin layer, and the resin layer constituting the back surface on the louver layer 1 side is referred to as a second resin layer. When the protective layer 4 is three or more layers, another resin layer is provided between the first resin layer and the second resin layer. As another resin layer, for example, a layer composed of another (meth) acrylic resin different from the (meth) acrylic resin constituting the first resin layer, and a polycarbonate constituting the second resin layer have a draw ratio. Examples include layers made of different polycarbonates.

  The first resin layer of the protective layer 4 is made of (meth) acrylic resin. By covering the outermost surface of the viewing angle control sheet 10 with the (meth) acrylic resin, the scratch resistance can be improved and the surface hardness can be increased. Here, (meth) acryl means acryl or methacryl.

  The surface hardness of the first resin layer of the protective layer 4 in the viewing angle control sheet 10 is JIS K 5600-5-4 “Paint General Test Method—Part 5: Mechanical Properties of Coating Film—Section 4: Scratch Hardness ( In the pencil scratch test according to the test method semi-prepared as “pencil method”, it may be HB or more, preferably H or more, more preferably 2H or more, and further preferably 3H or more.

Examples of the (meth) acrylic resin forming the first resin layer include (meth) acrylic acid ester (co) polymers, copolymers containing (meth) acrylic acid esters, and modified products thereof. It is done. Here, the (co) polymer means a polymer or a copolymer.
Examples of the (meth) acrylate ester (co) polymer include poly (meth) acrylate methyl, poly (meth) acrylate ethyl, poly (meth) acrylate propyl, poly (meth) acrylate butyl, ( And (meth) methyl acrylate / (meth) butyl acrylate copolymer, (meth) ethyl acrylate / (meth) butyl acrylate copolymer, and the like.
Examples of the copolymer containing a structural unit derived from the (meth) acrylate ester include ethylene / (meth) methyl acrylate copolymer, styrene / (meth) methyl acrylate copolymer, vinylcyclohexane / ( Examples thereof include a methyl methacrylate copolymer, maleic anhydride / methyl (meth) acrylate copolymer, and N-substituted maleimide / methyl (meth) acrylate copolymer.
Examples of the modified substance include a polymer in which a lactone ring structure is introduced by an intramolecular cyclization reaction; a polymer in which glutaric anhydride is introduced by an intramolecular cyclization reaction; and an imidizing agent (for example, methyl And polymers having an imide structure introduced by reaction with amine, cyclohexylamine, ammonia, etc.).
Among these, polymethyl methacrylate is preferable from the viewpoints of increasing surface hardness and high adhesion to polycarbonate.

  The second resin layer of the protective layer 4 is made of polycarbonate. Polycarbonate has good adhesion to the (meth) acrylic resin of the first resin layer and good adhesion to the louver layer 1 made of silicone rubber, and is excellent in rigidity and toughness. The balance of toughness is improved.

  If the first resin layer is not provided and the protective layer 4 is formed only of polycarbonate, the surface hardness is insufficient. Therefore, a dent is formed when the tip of a pencil or the like is rubbed, and the surface is easily scratched. On the other hand, when the protective layer 4 is formed only of (meth) acrylic resin without the second resin layer, the louver layer 1 cannot be given rigidity and is easily cracked by external stress. Another problem is that the adhesion to the louver layer 1 made of silicone rubber is low. Furthermore, when the first resin layer is not provided, there is a problem that the protective layer made only of polycarbonate is whitened.

  In the viewing angle control sheet 10, since the second resin layer made of polycarbonate is provided on one surface of the louver layer 1, the viewing angle control sheet 10 can be given rigidity and toughness. Moreover, since the 1st resin layer made from (meth) acrylic-type resin with high adhesiveness with respect to a polycarbonate is provided in the surface of the 2nd resin layer, it can provide high hardness to the outermost surface of the viewing angle control sheet 10. it can. As a result, even if the surface of the protective layer 4 is pushed with the tip of a pencil or the like, it does not easily dent, and even if it is rubbed, it is difficult to be damaged, so that it is suitable for instrument panels and switches.

From the viewpoint of improving the balance between the hardness of the surface of the viewing angle control sheet 10 and the internal toughness, the thickness of the first resin layer is thinner than the thickness of the second resin layer.
From the viewpoint of reducing the thickness of the protective layer 4 and the viewing angle control sheet 10, the total thickness of the first resin layer and the second resin layer is preferably 700 μm to 2000 μm, and more preferably 800 μm to 1500 μm.
From the viewpoint of achieving the above balance and thickness reduction, the thickness of the first resin layer is preferably 1 μm to 200 μm, and the thickness of the second resin layer is preferably 800 μm to 1200 μm. The thickness of the first resin layer is more preferably 20 μm to 150 μm, and the thickness of the second resin layer is more preferably 900 μm to 1000 μm. Furthermore, it is preferable that the thickness of the first resin layer is 50 μm to 100 μm, and the thickness of the second resin layer is 900 μm to 950 μm.

[Adhesive layer]
The viewing angle control sheet 10 has an adhesive layer (not shown) between the louver layer 1 and the protective layer 4. The adhesive layer of this embodiment is formed of silicone rubber. The adhesive layer may be formed of a known adhesive other than silicone rubber that bonds the resin layers together. However, since the louver layer 1 is made of silicone rubber, each of the adhesiveness with the louver layer 1, the reduction in interface reflection between the louver layer 1 and the adhesive layer, and the adhesiveness with the polycarbonate forming the second resin layer are good. In view of the above, the adhesive layer is preferably made of silicone rubber. Specific examples of the silicone rubber are the same as the specific examples of the silicone rubber of the louver layer 1 described later.
The thickness of the adhesive layer is thinner than that of the second resin layer, and can be, for example, about 0.1 μm to 50 μm, preferably 5 μm to 30 μm.

[Louvre layer 1]
(Light transmission band material)
The material of the light transmission band 2 constituting the louver layer 1 is preferably a highly transparent resin. Specifically, the light transmittance (light transmittance) when light is transmitted in the thickness direction of the louver layer 1 is 75% or more, preferably 85%, with respect to only the light transmission band 2 of the louver layer 1. A resin having high transparency as described above is preferable. Here, the upper limit value of the light transmittance is not particularly limited, and can be, for example, 99.99% or less. As the resin, for example, a highly transparent thermoplastic resin or thermosetting resin is used. Specific examples include a cellulose resin, a polyolefin resin, a polyester resin, a silicone resin, a polystyrene resin, and a polyvinyl chloride resin. , Acrylic resin, polycarbonate resin and the like. Of these, silicone resins are preferable, and silicone rubber is particularly preferable in terms of heat resistance, chemical resistance, decomposition resistance, transparency, flexibility, and the like. The silicone rubber may be a composition containing components other than the silicone resin.

  Examples of the silicone rubber include a silicone rubber composition generally called a millable rubber composed of a diorganopolysiloxane whose molecular chain end is blocked with a hydroxysilyl group or a vinylsilyl group and an organic peroxide; bonded to a silicon atom in the molecule. So-called addition reaction in which a diorganopolysiloxane having at least two vinyl groups is combined with an organohydrogenpolysiloxane having at least three hydrogen atoms bonded to silicon atoms (= SiH bonds) in the molecule and a platinum-based catalyst. Type organosilicone rubber composition.

(Shading band material)
The material of the light-shielding band 3 constituting the louver layer 1 is not particularly limited. For example, the light-transmitting band 2 is made of the above-described resin as a base material and added with a colorant such as a pigment or a dye. Colored resins are preferred. The resin material forming the light transmission band 2 and the resin material as the base material of the light shielding band 3 may be the same or different, but the adhesion between the light transmission band 2 and the light shielding band 3 may be different. It is preferable that the resin materials of both are the same from the viewpoint of easily improving the resistance.

  The color tone of the light-shielding band 3 may be sufficient as long as a sufficient light-shielding property is obtained. Examples thereof include black, red, yellow, green, blue, and light blue. The color tone and the light-shielding property of the light-shielding band 3 can be adjusted by the type and the amount of the colorant. Specifically, the light shielding property is such that only the light shielding zone 3 of the louver layer 1 has a light transmittance of 20% or less, preferably 5% or less when light is irradiated in the thickness direction of the louver layer 1. It is preferable to have. The light transmittance may be 0%. Moreover, since the color tone of the shading band is a color tone recognized when the louver layer 1 is viewed, it is preferable to design the shade in consideration of decorativeness.

  Specific examples of the colorant include general organic pigments or inorganic pigments such as carbon black, iron oxide, titanium oxide, yellow iron oxide, disazo yellow, and phthalocyanine blue. One colorant may be used, or two or more colorants may be used. Moreover, when not using a black pigment, it is preferable to use a white pigment together in order to obtain favorable light-shielding property.

(Width of light transmission band and light shielding band)
The width of the light transmission band 2 and the light shielding band 3 (thickness in the horizontal direction in FIG. 2) is freely set. The light transmittance of the louver layer 1 can be adjusted by the ratio of the width of the light transmission band 2 to the width of the light shielding band 3. The range of the viewing angle (visible angle) θ can be adjusted by the width of the light transmission band 2 and the thickness of the louver layer 1.

In consideration of achieving both viewing angle control and good visibility of the display screen, the width of the light transmission band 2 is preferably 40 to 200 μm, and more preferably 100 to 150 μm. Moreover, 1-50 micrometers is preferable and, as for the width | variety of the light shielding zone 3, 10-30 micrometers is more preferable. When each width is adjusted to the above range, for example, the viewing angle control sheet 10 having a light transmittance of 65% or more and a viewing angle θ30 to 120 ° is obtained.
The ratio represented by the width of the light shielding band 3 / the width of the light transmission band 2 is preferably 0.005 to 1, and more preferably 0.06 to 0.35.

  The thickness of the louver layer 1 is preferably 100 μm to 5000 μm, more preferably 150 μm to 1000 μm, and further preferably 200 μm to 500 μm. When the thickness of the louver layer 1 is in the above range, the viewing angle θ can be easily controlled.

[Base layer 5]
As a material of the base layer 5, for example, a thermoplastic resin or a thermosetting resin having high transparency is used. Specific examples include cellulose resins, polyolefin resins, polyester resins, silicone resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polycarbonate resins, and the like. Among these, polycarbonate is preferable from the viewpoint of improving heat resistance, rigidity, and toughness.
The protective layers 4 may be provided on both sides of the louver layer 1, and in this case, the base layer 5 is one of the protective layers 4.

  The thickness of the base layer 5 is preferably 50 μm to 300 μm, more preferably 75 μm to 250 μm, and still more preferably 100 μm to 200 μm. When the thickness of the base layer 5 is within the above range, the rigidity and thinning of the viewing angle control sheet 10 can be balanced.

  A transparent member such as an arbitrary transparent layer or transparent film may be installed on the outer surface 5a of the base layer 5, and examples thereof include a known adhesive layer, adhesive layer, transparent film, protective sheet and the like.

  Examples of the material for the adhesive layer include elastomeric adhesives, acrylic adhesives, urethane adhesives, rubber adhesives, and the like. Examples of the elastomer-based pressure-sensitive adhesive include pressure-sensitive adhesives including silicone rubber, silicone gel, urethane rubber, urethane gel and the like. When using an elastomer-based adhesive, it is preferable to apply a known mirror finish to the surface of the adhesive layer in order to increase its transparency.

  In the resin constituting the viewing angle control sheet 10, known additives in the resin film field such as an ultraviolet absorber, an infrared absorber, and a colorant are used for the purpose of improving the weather resistance and improving the design as necessary. It may be contained.

[Production method of viewing angle control sheet]
The louver layer 1 constituting the viewing angle control sheet 10 can be manufactured, for example, by the following method. First, a plurality of first sheets having a desired thickness made of the constituent material of the light transmission band 2 and a plurality of second sheets having a desired thickness made of the constituent material of the light shielding band 3 are alternately laminated. Then, heating and pressurizing are performed to form a block body in which these plural sheets are integrated.

  Next, the louver layer 1 is obtained by slicing the block body along a cut surface perpendicular to the sheet surface. The thickness at the time of slicing (slice width) corresponds to the thickness of the louver layer 1. By slicing the block body with a plane inclined with respect to the sheet surface, the angle formed by the surface of the louver layer 1 and the light shielding band 3 can be adjusted.

The method of laminating and integrating the louver layer 1, the protective layer 4, and the base layer 5 is not particularly limited, and a known method of laminating a resin layer can be used.
As an example, a method of applying an adhesive made of silicone rubber to the first surface of the louver layer 1 and bonding the protective layer 4 prepared in advance can be mentioned. The base layer 5 can be formed on the second surface of the louver layer 1 by the same method.

  The viewing angle control sheet 10 is obtained by laminating the louver layer 1, the protective layer 4, and the base layer 5, and forming the integrated laminated body into a desired shape. The planar shape of the viewing angle control sheet 10 is not particularly limited, and a rectangular shape, a polygonal shape, a circular shape, an elliptical shape, or the like may be appropriately adopted according to the shape of the display screen to be installed.

<< Viewing angle control sheet 20 >>
The case where the viewing angle control sheet according to the present invention includes one louver layer has been described above. The viewing angle control sheet according to the present invention may include two louver layers. Hereinafter, the configuration of the viewing angle control sheet 20 in which two louver layers are laminated will be described with reference to FIG.

  FIG. 3 is a perspective view schematically showing an enlarged part of the viewing angle control sheet 20. In FIG. 3, the thickness direction of the viewing angle control sheet 20 is the Z direction, the light source side of the light entering the sheet 20 is the Z1 side, and the irradiation side (viewing side) from which the light transmitted through the sheet 20 is emitted. ) On the Z2 side. Two directions perpendicular to each other in a plane perpendicular to the Z direction are defined as an X direction and a Y direction, respectively.

The viewing angle control sheet 20 has a first transparent resin layer 21, a first louver layer 22, a second transparent resin layer 23, a second louver layer 24, and a protective layer 25 stacked in order from the Z1 side in the thickness direction. Are integrated with each other.
The first transparent resin layer 21 is provided on the Z1 side surface (first surface) of the first louver layer 22, and the protective layer 25 is provided on the Z2 side surface (second surface) of the second louver layer 24. The second transparent resin layer 23 is provided on the Z2 side surface (second surface) of the first louver layer 22, that is, the Z1 side surface (first surface) of the second louver layer 24.
The overall planar shape of the viewing angle control sheet in the XY plane (a plane perpendicular to the Z direction) is, for example, a rectangle, but can be appropriately changed according to the shape of the place to be installed.

  The protective layer 25 of the viewing angle control sheet 20 has the same configuration as the protective layer 4 of the viewing angle control sheet 10. The first transparent resin layer 21 and the second transparent resin layer 23 of the viewing angle control sheet 20 have the same configuration as that of the base layer 5 of the viewing angle control sheet 10 independently.

  In the first louver layer 22, light transmission bands 26 and light shielding bands 27 are alternately repeated in the Y direction. Each of the light transmission band 26 and the light shielding band 27 has a band shape extending in the X direction, and the width in the Y direction is uniform and constant. The plurality of light transmission bands 26 have the same width, and the plurality of light shielding bands 27 have the same width.

  In the second louver layer 24, the light transmission band 28 and the light shielding band 29 are alternately repeated in the X direction. Each of the light transmission band 28 and the light shielding band 29 has a band shape extending in the Y direction, and the width in the X direction is uniform and constant. The plurality of light transmission bands 28 have the same width, and the plurality of light shielding bands 29 have the same width.

  In the viewing angle control sheet 20 shown in FIG. 3, the crossing angles of the light shielding bands of the louver layers 22 and 24 laminated in two layers are arranged so as to be about 90 ° in plan view. Here, the crossing angle may be an angle other than 90 °, or an arbitrary angle selected from 0 to 90 °. The thicknesses of the first louver layer 22 and the second louver layer 24 and the thicknesses of the light transmission band and the light shielding band in each louver layer are set independently, and may be the same or different.

The viewing angle control sheet 20 shown in FIG. 3 has a configuration in which two viewing angle control sheets 10 shown in FIG. 2 are stacked in two stages, and the second transparent resin layer 23 is shared by the upper and lower viewing angle control sheets 10. It is. Each transparent resin layer 21, 23 has the same configuration as the base layer 5 of the viewing angle control sheet 10.
In the viewing angle control sheet 20, the first louver layer 22 controls the viewing angle along the Y direction, and the second louver layer 24 controls the viewing angle along the X direction. The viewing angle in two directions can be controlled simultaneously.

  The manufacturing method of the viewing angle control sheet 20 is not particularly limited as long as the louver layers 22 and 24, the transparent resin layers 21 and 23, and the protective layer 25 are stacked and integrated. For example, the first transparent resin layer 21 is formed by applying a material for forming the first transparent resin layer 21 on the first surface of the first louver layer 22 and curing the material. Thereafter, a curable material for forming the second transparent resin layer 23 is applied to the second surface of the first louver layer 22, and the second louver layer 24 is placed on the coating film before being completely cured. Is cured. Thus, the second transparent resin layer 23 can be formed, and the first louver layer 22 and the second louver layer 24 can be bonded via the second transparent resin layer 23. Subsequently, the protective layer 25 is formed on the second surface of the second louver layer 24 to obtain the viewing angle control sheet 20. However, the first louver layer 22 and the second louver layer 24 may be bonded by an adhesive layer without using the second transparent resin layer 23. In this case, the thickness of the second transparent resin layer 23 can be reduced.

[Use of viewing angle control sheet]
By installing the viewing angle control sheet 10 in the vicinity of the display screen of the information display device so as to cover the display screen, so-called peeping can be prevented. Examples of the installation method include an installation method in which the outer surface 5a of the base layer 5 of the viewing angle control sheet 10 formed in a rectangular shape is brought into close contact with a transparent substrate constituting a display screen of the information display device. Since the viewing angle control sheet 10 has a high surface hardness of the protective layer 4 and excellent scratch resistance, it can be installed on the outer surface of the apparatus and exposed to the outside.
Moreover, the usage method which installs a viewing angle control sheet | seat so that the display screen of the instrument panel in a vehicle may be covered is also preferable. It is possible to prevent the light of the display screen from being reflected on the windshield.

The extending direction of the light transmission band 2 (and the light shielding band 3) of the installed viewing angle control sheet 10 and the sides of the display screen frame may be parallel or non-parallel. In order to prevent the occurrence of moiré fringes, the extending direction of the light transmission band 2 may be inclined with respect to the display screen frame (a bias angle may be provided).
Although the case of the viewing angle control sheet 10 has been described as a method of using the viewing angle control sheet according to the present invention, the viewing angle control sheet 20 can also be used in the same manner as described above.

The following examples are examples of the present invention, and the present invention may include examples not illustrated below.
[Example 1]
A viewing angle control sheet 10 shown in FIGS.
First, as a material for the light transmission band 2, a first sheet having a thickness of 125 μm made of transparent silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE153-U) was prepared.
Separately from this, as a material of the light-shielding band 3, a thickness composed of a material obtained by adding 15 parts by mass of carbon black to 100 parts by mass of transparent silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-153-U). A second sheet having a thickness of 10 μm was prepared.
A plurality of first sheets and a plurality of second sheets were alternately laminated and heated, vulcanized and pressurized to form a block body in which these sheets were integrated.

  The louver layer 1 was produced by slicing the block body to a thickness of 310 μm at a cut surface perpendicular to the sheet surface.

Next, a film in which an acrylic resin layer having a thickness of 75 μm and a polycarbonate layer having a thickness of 925 μm were laminated was prepared as the protective layer 4. A liquid silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-1987) is applied to the surface of the polycarbonate layer side of this film to a thickness of about 20 μm using a screen printer, and this coated surface is applied. It was placed on the first surface of the louver layer 1 and heat vulcanized and bonded.
In the same manner, a base layer 5 made of a polycarbonate layer having a thickness of 200 μm was formed on the second surface of the louver layer 1 to obtain a viewing angle control sheet 10.

The surface hardness of the protective layer 4 of the viewing angle control sheet 10 is changed to JIS K 5600-5-4 “Paint General Test Method—Part 5: Mechanical Properties of Coating Film—Section 4: Scratch Hardness (Pencil Method)” It investigated by the pencil scratching test by the test method to be quasi-treated. As a result, it was 3H.
Even if the surface of the protective layer 4 of the viewing angle control sheet 10 was repeatedly rubbed with the tip of the fingernail, it was not scratched, and no depression was produced even when it was pushed.
Since the surface of the viewing angle control sheet 10 was coated with an acrylic resin layer, the surface was highly resistant to chemicals, and the inner carbonate layer could be sufficiently prevented from being decomposed or whitened. Moreover, since the thick polycarbonate layer can suppress the deformation of the acrylic resin layer even under a high temperature environment, there was no concern about the deformation.

When the light transmittance of the viewing angle control sheet 10 was measured using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.), the total light transmittance was 80% and the haze was 4. Here, the haze is obtained by the equation “haze (%) = Td / Tt × 100”. In the formula, Td represents diffuse transmittance, and Tt represents total light transmittance.
The viewing angle of the viewing angle control sheet 10 was about 65 ° in a plane orthogonal to the longitudinal direction in which the light transmission band 2 and the light shielding band 3 of the louver layer 1 were extended.

[Example 2]
A viewing angle control sheet 10 was produced in the same manner as in Example 1 except that the thickness of the acrylic resin layer in the protective layer 4 was changed to 3 μm and the thickness of the polycarbonate layer was changed to 1000 μm.
As a result of testing the surface hardness of the protective layer 4 in the same manner as in Example 1, it was 2H. Further, no depression was generated even when the surface of the protective layer 4 was pushed in with the tip of the fingernail. However, when the protective layer 4 was repeatedly rubbed strongly with the tip of the fingernail, it was slightly scratched and more easily scratched than in Example 1. As in Example 1, there was no concern about whitening or deformation in a high temperature environment.

[Example 3]
A viewing angle control sheet 10 was produced in the same manner as in Example 1 except that the thickness of the acrylic resin layer in the protective layer 4 was 75 μm and the thickness of the polycarbonate layer was changed to 300 μm.
As a result of testing the surface hardness of the protective layer 4 in the same manner as in Example 1, it was HB. Further, even when the surface of the protective layer 4 was repeatedly rubbed with the tip of the fingernail, no damage was found. However, when the protective layer 4 was pushed in repeatedly at the tip of the fingernail, a small dent (dent) was formed, which was easier to dent than Example 1. As in Example 1, there was no concern about whitening or deformation in a high temperature environment.

[Comparative Example 1]
A viewing angle control sheet 10 was produced in the same manner as in Example 1 except that the acrylic resin layer in the protective layer 4 was not provided and the thickness of the polycarbonate layer was changed to 1000 μm.
As a result of testing the surface hardness of the protective layer 4 in the same manner as in Example 1, it was 2B. Further, when the surface of the protective layer 4 was repeatedly rubbed with the tip of the fingernail, it was easily scratched. Furthermore, there was concern about the problem of whitening due to hydrolysis in a high temperature environment.

[Comparative Example 2]
A viewing angle control sheet 10 was produced in the same manner as in Example 1 except that the thickness of the acrylic resin layer in the protective layer 4 was changed to 700 μm and the thickness of the polycarbonate layer was changed to 300 μm.
As a result of testing the surface hardness of the protective layer 4 in the same manner as in Example 1, it was 3H. Further, even when the surface of the protective layer 4 was repeatedly rubbed with the tip of the fingernail, no damage was found. However, since the acrylic resin layer is thicker than the polycarbonate layer, there is a concern that deformation of the acrylic resin layer cannot be suppressed by the polycarbonate layer in a high temperature environment.
The above results are shown in the following table.

DESCRIPTION OF SYMBOLS 1 ... Louver layer, 2 ... Light transmission zone, 3 ... Shading zone, 4 ... Protective layer, 4a ... Surface of protective layer, 5 ... Base layer, 5a ... Outer surface of base layer, 10 ... Viewing angle control sheet, 20 ... Viewing angle control Sheet, 21 ... first transparent resin layer, 22 ... first louver layer, 23 ... second transparent resin layer, 24 ... second louver layer, 25 ... protective layer, 26 ... light transmission band, 27 ... light shielding band, 28 ... Light transmission band, 29 ... Shading band

Claims (4)

A louver layer in which a light transmission band and a light shielding band are alternately and repeatedly provided;
Provided on one surface of the louver layer, and comprising at least a transparent protective layer,
At least one of the light transmission band and the light shielding band is formed of silicone rubber,
The protective layer has a multilayer structure composed of two or more resin layers,
The first resin layer constituting the surface opposite to the louver layer in the multilayer structure is formed of a (meth) acrylic resin,
The second resin layer constituting the back surface of the louver layer side of the multilayer structure is formed of polycarbonate,
The viewing angle control sheet, wherein the first resin layer is thinner than the second resin layer. The first resin layer has a thickness of 1 μm to 200 μm,
The second resin layer has a thickness of 800 μm to 1200 μm.
The viewing angle control sheet according to claim 1.   The viewing angle control sheet according to claim 1, further comprising an adhesive layer between the louver layer and the protective layer, wherein the adhesive layer is formed of silicone rubber.   The viewing angle control sheet according to any one of claims 1 to 3, further comprising a base layer that is at least partially transparent on the other surface of the louver layer.

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