JP2021076682A - Light control filter - Google Patents

Abstract

To provide a light control filter with improved optical characteristics.SOLUTION: A light control filter (20) is provided, comprising an elastomer sheet (1) having a plurality of through-holes (2) formed therethrough in a thickness direction, and a transparent base material (3) provided on at least one surface of the sheet to cover the at least one surface and openings of the plurality of through-holes. The transparent base material may be pasted on the at least one surface via an adhesive layer (4). The sheet is provided with micro protrusions (5) on at least one surface thereof including areas around the openings of the plurality of through-holes, where at least portions of the micro protrusions may cut into the adhesive layer.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical control filter.

Conventionally, a film-shaped light control filter for adjusting the light transmittance and the viewing angle has been known. For example, Patent Document 1 is made of silicon and includes a substrate that transmits incident light and an optical member that is provided with a plurality of through holes and regulates the angle of light incident on the substrate by the through holes. Interference filters are disclosed.

JP 2015-049276

However, when the interference filter of Patent Document 1 is attached to the surface of a glass base material with an adhesive or an adhesive interposed therebetween, a part of the adhesive or the adhesive gets into the recesses opened on the surface of the interference filter. As a result, there is a problem that the optical characteristics of the interference filter are disturbed (see FIG. 11). Further, the through hole provided in the silicon optical member tends to have a tapered shape in which the diameter is reduced from one opening to the other opening in the manufacturing process by the photolithography, and in order to form a non-tapered through hole. There was a problem that an advanced etching process was required. Using an optical member with a deep through hole as a base material, the optical member cut out by slicing a portion with a loose taper shape from this base material requires time and effort to remove silicon shavings due to cutting out from the through hole. It was. Due to these problems, the optical characteristics of the optical member provided with the through hole are not always satisfactory.

The present invention provides an optical control filter with improved optical properties.

[1] An elastomer sheet provided with a plurality of through holes in the thickness direction, and a transparent base material covering the one surface and the openings of the plurality of through holes on at least one surface side of the sheet. Equipped with an optical control filter.
[2] The light control filter according to [1], wherein the transparent base material is attached to one of the surfaces via an adhesive layer.
[3] At least one of the contact surface of the sheet with respect to the transparent base material and the contact surface of the transparent base material with respect to the sheet is surface-treated, and the sheet and the transparent base material have an adhesive layer. The optical control filter according to [1], which is joined without interposing.
[4] The optical control according to any one of [1] to [3], wherein microprojections are provided on at least one surface of the sheet, including the periphery of the openings of the plurality of through holes. filter.
[5] On at least one surface of the sheet, microprojections are provided including the periphery of the openings of the plurality of through holes, and at least a part of the microprojections bites into the adhesive layer. , [2].

In the optical control filter of the present invention, since the sheet having through holes through which light is transmitted is made of an elastomer, even if an adhesive or the like is present at the interface between the sheet and the transparent base material, it receives a pressing force. At that time, it is reduced that the adhesive or the like invades (inflows) into the through hole of the sheet. As a result, the light transmitted through the through hole of the sheet is less likely to be scattered by the adhesive or the like in the through hole, so that excellent optical characteristics can be obtained.

It is a partial cross-sectional view of the light control filter 10 of the 1st Embodiment of this invention. It is a partial cross-sectional view of the light control filter 20 of the 2nd Embodiment of this invention. It is a partial cross-sectional view of the sheet 1 which constitutes an optical control filter 20. It is sectional drawing which showed the state of manufacturing the sheet 1. (A) A state in which the elastomer precursor L is applied to the surface of the molding die K. (B) A state in which the elastomer precursor L overflowing from the recess M of the molding die K forms a residual film N. (C) Sheet 1 taken out from the molding die K and from which the residual film N has been removed. (A) It is a photograph (magnification: 200 times) which shows the appearance that the microprojection 5 was formed on the first surface 1a of the sheet 1 made of silicone rubber. (B) This is the result of measuring the unevenness of the first surface 1a along the white line in the photograph. It is a partial cross-sectional view which shows the appearance of attaching the transparent base material 3 to the sheet 1 which has a smooth surface. It is a partial cross-sectional view which shows the state that the transparent base material 3 is attached to the sheet 1 which has a step S. It is a partial cross-sectional view which shows the appearance which a part of the through hole 2 of a sheet 1 was deformed. FIG. 5 is a partial cross-sectional view showing a state in which a transparent base material 3 is attached to a sheet 1 having a step S and minute protrusions 5 on its surface. FIG. 5 is a partial cross-sectional view showing a state in which the transparent base material 3 is attached to the sheet 1 while maintaining the step S. It is a partial cross-sectional view of the optical control filter 100 of the comparative example.

The optical control filter of the present invention comprises an elastomer sheet provided with a plurality of through holes in the thickness direction, and a transparent sheet that covers the one surface and the openings of the plurality of through holes on at least one surface side of the sheet. It is an optical control filter provided with a base material.

<First Embodiment>
FIG. 1 shows a partial cross-sectional view of the optical control filter 10 of the first embodiment of the present invention cut in the thickness direction.
[Sheet 1]
The elastomer sheet 1 is formed with a plurality of through holes 2 penetrating from the first surface 1a to the second surface 1b in the thickness direction. The elastomer constituting the sheet 1 contains a light-shielding material, and light incident on the first surface 1a or the second surface 1b from the outside mainly passes through the through hole 2. That is, the sheet 1 is a sheet having a sea-island structure including a light transmitting portion and a light shielding portion.

When the second surface 1b of the sheet 1 is viewed in a plan view, the total area of the plurality of through holes 2 (total area of the light transmitting portion) with respect to the total area of the second surface 1b (total area of the light transmitting portion and the light shielding portion). The ratio may be adjusted according to the method of using the optical control filter 10, and an example of a specific ratio will be described later.

Examples of the elastomer include thermoplastic elastomers such as urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, styrene butadiene rubber, and silicone rubber; urethane-based, ester-based, styrene-based, and olefin-based elastomers. Examples thereof include thermoplastic elastomers such as butadiene-based or fluorine-based; or composites thereof. Among these, silicone rubber is preferable because it has a small dimensional change after being taken out from the molding die, which will be described later, does not warp after being taken out from the molding die, has a small compression set, and has high heat resistance.

The elastomer is preferably a polymer having a shore hardness A of 80 or less as measured using a durometer according to JIS K6253.
When the shore hardness A is in the above-mentioned preferable range, the stress received from the outside can be easily absorbed by the elasticity of the sheet 1, so that the adhesive layer 4 in contact with the first surface 1a of the sheet 1 is adhered. It is possible to further reduce the infiltration (inflow) of the adhesive into the inside of the through hole 2 due to the stress.

The MD-1 rubber hardness of the elastomer constituting the sea portion is preferably 25 or more and 80 or less, more preferably 40 or more and 75 or less, and further preferably 50 or more and 70 or less.
When the MD-1 rubber hardness is at least the above lower limit value, it becomes easy to cut an excess residual film after taking out the sheet 1 from the molding die at the time of manufacturing, and a smooth main surface can be easily obtained. .. When the MD-1 rubber hardness is not more than the above upper limit value, the sheet 1 can be easily taken out from the molding die at the time of manufacturing.
The MD-1 rubber hardness of the sheet 1 was measured by pressing the sea portion in the thickness direction of the sheet 1 at a temperature of 21 to 25 ° C., preferably 23 ° C., using a micro rubber hardness tester. The value. In the measurement, the hardness is measured by reading with a detector the amount of displacement generated when the push needle provided in the micro rubber hardness tester deforms the surface of the test piece. The points pressed by the push needle shall be 10 or more points in the sea portion randomly selected, and the average value thereof shall be the measured value. Usually, the MD-1 rubber hardness shows a value close to the value measured by the type A durometer (shore A hardness) defined in JIS K6253-3: 2012. By using a micro rubber hardness tester, the hardness of a thin test piece can be easily measured. However, when the thickness of the sheet 1 (test piece) is less than 1.0 mm, the thickness of the laminated body obtained by stacking a plurality of the same sheet 1 to form a laminated body and stacking the minimum number of sheets of 1.0 mm or more. Measure the hardness in the longitudinal direction.
As the micro rubber hardness tester to be used, "micro rubber hardness tester" manufactured by Polymer Meter Co., Ltd., trade name: MD-1capa is preferable. The load system of this micro rubber hardness tester is a cantilever beam leaf spring. The needle pusher shape is type A (height 0.50 mm, φ0.16 mm, cylindrical shape), the pressure leg size is type A (outer diameter 4.0 mm, inner diameter 1.5 mm), and the spring load is 22 mN (2.24 g). , Measurement mode is set to normal mode, respectively.
As a specific measurement method, for example, the island portion where the through hole is formed is removed by laser irradiation or the like to obtain a sheet 1 composed of only the sea portion, which is used as a test piece. The temperature of the test piece and the test chamber for measuring the hardness of the MD-1 rubber is 21 to 25 ° C, preferably 23 ° C.

The MD-1 rubber hardness of the entire sheet 1 including the sea portion and the island portion is preferably 25 or more and 80 or less, more preferably 40 or more and 75 or more, and further preferably 50 or more and 70 or more.
When the MD-1 rubber hardness of the entire sheet 1 is in the above range, it has high flexibility and can be easily elastically deformed, which is preferable.
The MD-1 rubber hardness of the entire sheet 1 was measured at 10 or more randomly selected MD-1 rubber hardnesses in the thickness direction of the sheet 1 based on the above measurement method, and the measured values were averaged. Obtained by doing.

As the plan view shape of the sheet 1, for example, a rectangular shape, a circular shape, an elliptical shape, a polygonal shape, or any other shape can be adopted.
The vertical × horizontal size of the sheet 1 is not particularly limited, and may be, for example, 5 mm × 5 mm to 100 cm × 100 cm.

The thickness of the sheet 1 is, for example, preferably 50 μm or more and 1000 μm or less, more preferably 80 μm or more and 500 μm or less, and further preferably 100 μm or more and 300 μm or less.
When the thickness is at least the lower limit value, it becomes easier to control the transmission angle (viewing angle) of the light transmitted through the sheet 1. When the thickness is equal to or less than the upper limit value, the flexibility becomes higher.
The thickness of the sheet 1 is determined as the average value of the values measured at 10 or more randomly selected cross sections. A known microstructure observation means such as a measuring microscope is applied to the measurement.

When the sheet 1 is viewed in a plan view, the total area of the elastomer portion (light-shielding portion) with respect to the total area of the second surface 1b including the opening (light transmitting portion) of the through hole 2 is, for example, 36 to 99.2%. Preferably, 49-96% is more preferable, and 65-91% is even more preferable. It is preferable that the total area of the elastomer portions on the first surface 1a is the same as the total area of the elastomer portions on the second surface 1b.
Each of the above areas can be obtained by performing image processing on an image obtained by photographing each surface by a known method.

(Light transmitting part)
The light transmitting portion formed by the plurality of through holes 2 of the sheet 1 is an island portion of the sea island structure, and is a plurality of columnar transparent portions independent of each other by the sea portion. Since each through hole 2 penetrates the sheet 1 in the thickness direction, the first opening of each through hole 2 opens to the first surface 1a of the sheet 1, and the second opening of each through hole 2 is open. , It is open to the second surface 1b of the sheet 1. The through holes 2 are arranged at a constant pitch along the surface direction of the sheet 1. Each through hole 2 is filled with a gas such as air.

The shape of the through hole 2 is preferably columnar. Examples of the cross-sectional shape obtained by cutting the through hole 2 in the plane direction of the sheet 1 include a circle, an ellipse, a quadrangle, and other polygons.
The shape of the openings of the plurality of through holes 2 and the cross-sectional shape may be the same or different from each other, but are preferably the same from the viewpoint of ease of controlling light transmission.
The shape of the first opening that opens to the first surface 1a of the single through hole 2 (the shape of the opening that views the first surface 1a in a plan view) and the shape of the second opening that opens to the second surface 1b (the first). The shapes of the openings in which the two surfaces 1b are viewed in a plan view) may be the same or different from each other, but are preferably the same from the viewpoint of ease of controlling light transmission.

When the taper on the side surface of the through hole 2 is substantially perpendicular to the first surface 1a or the second surface 1b of the sheet 1, the angle between the incident light and the emitted light is small, which is preferable. Here, the taper of the side surface of the through hole 2 is substantially perpendicular to the first surface 1a or the second surface 1b of the sheet, which means that the taper angle (with respect to the perpendicular line of the first surface 1a or the second surface 1b of the sheet). The sharp angle formed by the side surface of the through hole 2) is 0.75 degrees or less. The taper angle is preferably 0.38 degrees or less, more preferably 0.2 degrees or less.

The axis of the central axis of the columnar through hole 2 may be perpendicular to or inclined with respect to the first surface 1a and the second surface 1b, and may be easy to manufacture and control the light transmission angle. From the viewpoint, it is preferably substantially vertical. Here, substantially vertical means that they intersect at 90 ° ± 2 °. When substantially vertical, the height H of the columnar through hole 2 is substantially the same as the thickness of the sheet 1.
The angle formed by the axis and the surface of the sheet 1 and the height H of the through hole 2 are known fine details such as a measuring microscope or the like to obtain a cross section including the through hole 2 and the first surface 1a and the second surface 1b of the sheet 1. It is obtained by measuring with a structural observation means.

For each through hole 2, the diameter R of the opening opened on each surface is the diameter of the smallest circle including the opening. The diameter is preferably, for example, 5 μm to 100 μm, more preferably 10 μm to 50 μm, from the viewpoint of easy control of the transmission angle of the light transmitted through the sheet 1. The diameters R of the two openings opened on each surface of the single through hole 2 may be the same as or different from each other.
The average diameter of 10 or more through holes 2 randomly selected from the plurality of through holes 2 on any surface of the sheet 1 is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.
The diameter can be measured by a known microstructure observing means such as a measuring microscope.

The aspect ratio represented by (diameter R: height H) of the columnar through hole 2 is preferably 1: 5 to 1:30, more preferably 1: 8.5 to 1: 25.5, and 1:15. ~ 1:20 is more preferable.
When the aspect ratio is 1: 5 to 1:30 and the through hole 2 is hollow, the viewing angle θ is 22.6 ° to 3.6 °. When the aspect ratio is 1: 8.5 to 1: 25.5, the viewing angle θ is 13.4 ° to 4.5 °. When the aspect ratio is 1:15 to 1:20, the viewing angle θ is 7.6 ° to 5.7 °.
When the through hole 2 is filled with the transparent material, the refractive index of the transparent material is larger than that of normal air, so that the viewing angle θ is wider than the range in the hollow case shown above. Therefore, from the viewpoint of narrowing the viewing angle θ, the through hole 2 is preferably hollow.
When it is at least the lower limit of the above range, it becomes easy to control the transmission angle of the light transmitted through the through hole 2 of the sheet 1.
When it is equal to or less than the upper limit of the above range, the amount of light transmitted through the through hole 2 of the sheet 1 can be increased. Moreover, it can be manufactured relatively easily.
The aspect ratio is the average value obtained by measuring the diameter R of both openings and the average value obtained by measuring the height H of 10 or more through holes 2 randomly selected from the plurality of through holes 2 of the sheet 1. The ratio to the value. The individual diameter R and height H can be measured using a known microstructure observing means such as a measuring microscope.

The pitch of the arrangement of the through holes 2 on the first surface 1a and the second surface 1b, that is, the pitch between the adjacent ends of the through holes 2 opened on each surface is between the centers of the smallest circles including the individual openings. The distance. This pitch is preferably, for example, 10 μm to 500 μm, more preferably 15 μm to 300 μm, and even more preferably 20 μm to 200 μm, from the viewpoint of easy control of the transmission angle of the light transmitted through the sheet 1.
The pitch is preferably constant on each surface. The pitches of the faces may be the same or different from each other.
The pitch is obtained by performing image processing on an image obtained by photographing an arbitrary surface by a known method.

The arrangement of the openings of the through holes 2 on the first surface 1a and the second surface 1b can be, for example, a two-dimensional array-like arrangement of X columns × Y rows. The arrangement of the through holes 2 is not limited to this example, and any arrangement pattern is adopted. In column X × row Y, for example, X and Y can be independently arbitrary integers of 10 to 1000. The arrangement pattern may be a two-dimensional array, a zigzag pattern, any other pattern, or a random random arrangement.

(Shading part)
The light-shielding portion of the sheet 1 is a sea portion of the sea-island structure, and is an opaque portion excluding the through hole 2.
The thickness of the light-shielding portion is the same as the thickness of the sheet 1, and is preferably 50 μm or more and 1000 μm or less, more preferably 80 μm or more and 500 μm or less, and further preferably 100 μm or more and 300 μm or less. When the length is equal to or more than the lower limit value, the controllability of light transmission becomes higher. When the length is equal to or less than the upper limit value, the flexibility becomes higher.

The content of the elastomer in the elastomer sheet 1 with respect to the total mass of the light-shielding portion is preferably 50 to 99% by mass, more preferably 60 to 97% by mass, still more preferably 70 to 95% by mass.
When the content is 50% by mass or more, the flexibility of the sheet 1 is sufficiently increased. When the content is 99% by mass or less, there is room for the light-shielding portion to sufficiently contain the light-shielding material. The balance of the total mass excluding the elastomer content can be assigned to the light-shielding material.

A known elastomer can be applied as the elastomer constituting the sheet 1. The elastomer may be transparent or opaque. The elastomer may be one kind or two or more kinds.

The light-shielding portion constituting the sheet 1 preferably contains a light-shielding material in addition to the elastomer. As the light-shielding material, at least one of a light-absorbing material and a light-reflecting material is used.
The light-absorbing material contains a light-absorbing agent. Examples of the light absorber include carbon, dyes, pigments and the like. Among the light absorbers, carbon is preferable because it has excellent light absorption. Examples of carbon include carbon black, graphite, carbon fiber and the like, and carbon black is preferable because it is versatile as a light absorber.
Examples of the light-reflecting material include metals. Examples of the metal include aluminum, silver, gold, chromium, nickel and the like.

[Transparent base material 3]
The transparent base material 3 is a transparent member that covers the first surface 1a of the sheet 1. Here, "transparent" means that light is sufficiently transmitted, and may not be colorless or may be colored.
The light transmittance of the transparent base material 3 that covers directly above the through hole 2 is preferably 70% or more, more preferably 80% or more, still more preferably 90% or more.
_{The above-mentioned light transmittance value is measured on the optical path of the inspection light in a device that uses D 65} specified in JIS Z 8720 as a light source and measures the intensity of the inspection light emitted from the light source with a light receiving sensor. The output value of the light receiving sensor when there is no object is A, and the output value when the object to be measured is set on the optical path of the inspection light and the transmitted light transmitted through the object is received by the light receiving sensor is B. When this is done, the value obtained by light transmittance = (B / A) × 100 (unit:%) is used.
The light transmittance of the transparent substrate 3 is determined as an average value of the values measured by the above method for the portion directly above the 10 randomly selected through holes 2.

The transparent base material 3 is a transparent member that covers the first surface 1a of the sheet 1. Although it is a plate-shaped member in the present embodiment, its shape is not limited to the plate shape and can be any shape.
If the surface of the transparent base material 3 exposed to the outside is smooth, diffuse reflection of light on the surface is prevented, and it becomes easy to see through the opposite side of the light control filter 10 through the through hole 2 of the sheet 1. ..
The arithmetic mean roughness (Ra) of the surface of the transparent substrate 3 exposed to the outside is preferably 0 μm or more and 1 μm or less, and more preferably 0 μm or more and 0.2 μm or less. Here, the arithmetic mean roughness (Ra) is a value obtained according to JIS B 0601: 2013 (ISO4287: 1997).

The constituent material of the transparent base material 3 may be transparent, and examples thereof include glass and a transparent synthetic resin. Specific examples thereof include silicone, polyurethane, acrylic resin, epoxy resin, polyester, polycarbonate, cycloolefin, liquid crystal polymer and the like.
When the transparent base material 3 is glass, the rigidity and heat resistance of the light control filter 10 can be improved.
From the viewpoint of enhancing the adhesiveness of the transparent base material 3 to the sheet 1, at least one of the contact surface (adhesive surface) of the transparent base material 3 and the contact surface (adhesive surface) of the sheet 1 must be surface-treated. preferable.
Examples of the surface treatment include excimer UV irradiation treatment, plasma treatment, corona treatment, and primer coating treatment such as a silane coupling agent.

As the plan view shape of the transparent base material 3, for example, a rectangular shape, a circular shape, an elliptical shape, a polygonal shape, or any other shape can be adopted.
The vertical × horizontal size of the transparent base material 3 is not particularly limited, and may be, for example, 5 mm × 5 mm to 100 cm × 100 cm.
The shape and size of the transparent base material 3 in a plan view may be the same as or different from the shape and size of the sheet 1 in a plan view.

The thickness of the transparent substrate 3 is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 175 μm or less, and further preferably 5 μm or more and 150 μm or less.
When the thickness of the transparent base material is at least the lower limit value, it becomes easy to impart rigidity to the light control filter 10, and when it is at least the upper limit value, sufficient light transmission can be ensured.
The thickness of the transparent base material 3 is determined as an average value of values measured at 10 or more locations whose cross sections are randomly selected. A known microstructure observation means such as a measuring microscope is applied to the measurement.

[Adhesive layer 4]
The adhesive layer 4 is a layer having adhesiveness or adhesiveness, which contains at least one of an adhesive and an adhesive.
In the field of adhesives, adhesives are generally used with the recognition that they can be adhered semi-permanently and adhesives are temporarily adhered. However, even an adhesive can be adhered semi-permanently by a curing treatment, so it is difficult to distinguish between an adhesive and an adhesive only by name. Therefore, in the present specification, the term "adhesive" may be used as a general term for adhesives and adhesives, and the term "adhesive" may be used as a general term for adhesives and adhesives. ..

A known adhesive can be applied as the adhesive contained in the adhesive layer 4. An acrylic adhesive is a suitable adhesive because it has good adhesiveness to the sheet 1 and the transparent substrate 3.

(Acrylic adhesive)
The acrylic adhesive can be integrated by laminating the surfaces of the same or different types of solids. The acrylic adhesive contains an acrylic resin (acrylic polymer). The content of the acrylic resin with respect to the total mass of the adhesive layer is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and 100% by mass. It may be.

Specific examples of the acrylic monomer forming the acrylic resin include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate, and ditri. Methylolpropantetraacrylate, 2-hydroxy-3-phenoxypropyl acrylate, bisphenol A / ethylene oxide modified diacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, dipropylene glycol diacrylate, Trimethylol propanetriacrylate, glycerin propoxytriacrylate, 4-hydroxybutyl acrylate, 1,6-hexanediol diacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobornyl acrylate, polyethylene glycol diacrylate, pentaerythritol Acrylate such as triacrylate, tetrahydrofurfuryl acrylate, trimethylpropan triacrylate, tripropylene glycol diacrylate; tetraethylene glycol dimethacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, allyl methacrylate, 1, 3-butylene glycol dimethacrylate, benzyl methacrylate, cyclohexyl methacrylate, diethylene glycol dimethacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, 1,6-hexanediol dimethacrylate, 2-hydroxyethyl methacrylate, isobornyl methacrylate, lauryl methacrylate, phenoxyethyl Methacrylate, Tetrahydrofurfuryl Methacrylate, Trimethylol Propane Trimethacrylate, etc. Methacrylate; Diacetoneacrylamide, N, N-dimethylacrylamide, Dimethylaminopropylacrylamide, Dimethylaminopropylmethacrylate, Methacrylate, N-methylolacrylamide, Acryloylformolin, N-methylacrylamide, N-isopropylacrylamide, Nt-butylacrylamide, N-phenylacrylamide, Examples thereof include (meth) acrylamide such as acryloyl piperidine and 2-hydroxyethyl acrylamide. One of these acrylic monomers may be used alone, or two or more thereof may be used in combination. It is also possible to adjust the adhesiveness by using two or more kinds of acrylic monomers.

The acrylic resin may be a copolymerization of an acrylic monomer and a vinyl monomer other than the acrylic monomer.
Examples of the vinyl-based monomer include styrene, α-methylstyrene, vinyl acetate, acrylonitrile, methacrylonitrile, maleic anhydride and the like.
The content of the acrylic monomer unit in the copolymer is preferably 50 mol% or more and less than 100 mol%, and more preferably 70 mol% or more and 98 mol% or less.
When the content of the acrylic monomer unit is at least the above lower limit value, the adhesiveness can be easily exhibited.
The content of the vinyl-based monomer unit in the above-mentioned copolymer can be, for example, 2 mol% or more and 20 mol% or less.

The range of the glass transition temperature of the acrylic resin contained in the adhesive layer 4 is preferably −80 ° C. or higher and 80 ° C. or lower, more preferably −60 ° C. or higher and 50 ° C. or lower, and further preferably −40 ° C. or higher and 0 ° C. or lower. ..
When it is equal to or higher than the lower limit of the above range, the viscosity of the adhesive adhesive contained in the adhesive layer 4 increases, and the adhesive layer 4 invades the inside of the through hole 2 when stress is applied from the outside ( Inflow) can be further suppressed.
When it is not more than the upper limit value of the above range, sufficient adhesiveness of the adhesive layer 4 can be obtained.
The glass transition temperature of the acrylic resin can be determined by differential scanning calorimetry or dynamic viscoelasticity measurement.

Examples of the acrylic monomer having a tendency to lower the glass transition temperature of the acrylic resin include ethyl acrylate, butyl acrylate (particularly n-butyl acrylate), 2-ethylhexyl acrylate and the like. In acrylic resins, the higher the proportion of these monomer units, the lower the glass transition temperature.

The mass average molecular weight of the acrylic resin is preferably 10,000 or more and 2 million or less, and more preferably 30,000 or more and 1 million or less. When the mass average molecular weight of the acrylic resin is at least the above lower limit value, a sufficient cohesive force can be secured and the cohesive failure of the adhesive layer 4 can be prevented.
On the other hand, if it is not more than the upper limit value, the adhesiveness can be further improved.

When the acrylic resin has an acrylic monomer unit having a reactive functional group, it may be cured by reacting with a curing agent. When the acrylic resin is cured, the cohesive force of the adhesive layer 4 is improved and the strength can be improved. Further, by improving the cohesive force of the adhesive layer 4, it is possible to obtain a removable adhesive layer 4 capable of repeating adhesion and peeling. Examples of the reactive functional group include a hydroxy group, a carboxy group, an amino group, an amide group, an epoxy group and the like.

The adhesive layer 4 may contain an arbitrary component other than the adhesive.
Examples of the optional component include a curing agent, a dispersion medium, and other additives.

The thickness of the adhesive layer 4 is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.5 μm or more and 500 μm or less, further preferably 1 μm or more and 100 μm or less, and 3 μm or more and 50 μm or less. Is particularly preferable.
When the thickness of the adhesive layer 4 is not less than the lower limit value, the adhesiveness is enhanced, and when it is not more than the upper limit value, the adhesive layer 4 is formed in the through hole 2 when stress is applied from the outside. It is possible to further suppress the intrusion (inflow) into the inside.
The thickness of the adhesive layer 4 is determined as an average value of values measured at 10 or more randomly selected cross sections. A known microstructure observation means such as a measuring microscope is applied to the measurement.

The thickness ratio represented by (thickness of adhesive layer 4 / thickness of sheet 1) is preferably 0.04 or more and 1 or less, more preferably 0.1 or more and 0.8 or less, and 0.2 or more. 0.5 or less is more preferable.
When the thickness ratio is at least the lower limit value, the adhesiveness is enhanced.
When the thickness ratio is equal to or less than the upper limit value, even if a part of the adhesive layer 4 enters (flows into) the inside of the through hole 2 when stress is applied from the outside, the through hole 2 It is possible to prevent the internal space from being filled.

<Effect>
In the light control filter 10 illustrated in FIG. 1, the sheet 1 provided with the through hole 2 for transmitting light is made of an elastomer. Therefore, for example, when a stress is applied from the outside by being pressed or bent, the sheet 1 can absorb the stress. As a result, it is possible to suppress or reduce a part of the adhesive layer 4 from invading (inflowing) into the through hole 2. Therefore, even if stress is applied to the optical control filter 10 from the outside, excellent optical characteristics are maintained.
On the other hand, in the optical control filter 100 of the comparative example shown in FIG. 11, the main body 101 provided with the through hole 102 for transmitting light is made of a non-elastomer hard member (for example, silicon). Therefore, for example, when the transparent base material 103 is pressed from the outside and stress is applied, the main body 101 cannot absorb the stress, so that most of the stress causes the adhesive layer 104 to flow. concentrate. As a result, a part of the adhesive layer 104 invades (inflows) into the through hole 102 to form a convex lens-shaped invaginated portion as shown in the figure. When the indentation part is formed, there is a problem that light that is not originally transmitted through the dotted optical path (reference numeral I in FIG. 11) is refracted by the lens effect of the indentation part and is transmitted through the solid line optical path. Occurs.

Regarding the optical control filter 10 of the first embodiment described above, the case where the transparent base material 3 and the adhesive layer 4 are provided only on the first surface 1a side of the sheet 1 has been described. Similarly, the transparent base material 3 and the adhesive layer 4 may be provided on the two surfaces 1b.

Further, although not shown, the optical control filter 10 of the present embodiment may not include the adhesive layer 4. In this case, the first surface 1a of the sheet 1 and the transparent base material 3 are joined. If at least one of the contact surface (bonding surface) of the first surface 1a and the transparent base material 3 is subjected to the above-mentioned surface treatment, it can be easily bonded by pressure bonding or heating.
If the optical control filter 10 does not have the adhesive layer 4, the adhesive layer 4 does not intrude into the through hole 2 even if stress is applied from the outside, and excellent optical characteristics are obtained. Is maintained.

<Second embodiment>
FIG. 2 shows a partial cross-sectional view of the optical control filter 20 of the second embodiment of the present invention cut in the thickness direction. Further, FIG. 3 shows a partial cross-sectional view in which only the sheet 1 constituting the optical control filter 20 is taken out and cut in the thickness direction thereof.
In the optical control filter 20, the same members as those of the optical control filter 10 described above are designated by the same reference numerals, and the description thereof will be omitted.

The difference between the optical control filter 20 and the above-mentioned optical control filter 10 is that a plurality of microprojections 5 are formed on the surface of the first surface 1a on the transparent base material 3 side of the sheet 1, so that fine irregularities are formed. It is a point provided. The microprojections 5 are formed over the entire surface of the first surface 1a, and as shown in the figure, a plurality of microprojections 5 are also formed around the opening of the through hole 2. Due to the presence of the plurality of microprojections 5, the separation distance between the first surface 1a of the sheet 1 and the adhesive layer 4 and the transparent base material 3 is longer than that of the optical control filter 10 of the first embodiment. ..

The constituent material of the microprojections 5 is the same as the elastomer which is the constituent material of the sheet 1.
The microprojections 5 are formed by scraping the first surface 1a of the sheet 1, and there is no adhesive surface for connecting the microprojections 5 and the sheet 1. That is, since the microprojections 5 and the first surface 1a of the sheet 1 are integrated, there is no possibility that the microprojections 5 will peel off from the first surface 1a of the sheet 1 when stress is applied from the outside.

As shown in the figure, the shape of the microprojection 5 is preferably a pyramid shape (vertical cone) that rises from the first surface 1a of the sheet 1 and shrinks in diameter from the base end to the tip end. If it is in the shape of a weight, a part of the tip side of the microprojection 5 bites (anchorings) into the adhesive layer 4 to exert an anchor function, and the sheet 1, the adhesive layer 4 and the transparent base material 3 are exhibited. Adhesion with is improved. The tip of the microprojection 5 may not bite into the adhesive layer 4 but may be deformed to become flat and adhere to the surface of the adhesive layer 4. Further, the tip of the microprojection 5 may penetrate the adhesive layer 4 and come into contact with the transparent base material 3, or may be inside the adhesive layer 4 without reaching the transparent base material 3. ..

The height of the microprojections 5, that is, the distance from the first surface 1a (base end of the microprojections 5) to the tip of the microprojections 5 is preferably, for example, 0.1 μm or more and 3 μm or less, and 0.2 μm or more and 2 μm or less. It is preferable, and more preferably 0.5 μm or more and 1.5 m or less.
When the height of the microprojections 5 is equal to or greater than the lower limit of the above range, the separation distance between the first surface 1a of the sheet 1 and the adhesive layer 4 and the transparent base material 3 can be sufficiently lengthened.
When the height of the microprojections 5 is not more than the upper limit of the above range, the adhesive force of the adhesive layer 4 and the transparent base material 3 with respect to the first surface 1a of the sheet 1 can be sufficiently enhanced.
The height of the microprojections 5 is determined as an average value measured for 10 or more randomly selected microprojections 5 on the first surface 1a of the sheet 1.
The height can be measured by a known microstructure observing means such as a measuring microscope. Examples of the microstructure observation means include a laser microscope, a scanning electron microscope, a digital microscope, a white interference microscope, an X-ray microscope, and a scanning probe microscope, but other observation means may be used. FIG. 5 shows the results of measurement with a laser microscope.

The arithmetic mean roughness Ra of the first surface 1a of the sheet 1 including the microprojections 5 is, for example, preferably 0.01 μm or more and 1.0 μm or less, more preferably 0.05 μm or more and 0.75 μm or less, and 0.1 μm or more and 0. It is more preferably 5.5 μm or less. When the arithmetic mean roughness Ra is equal to or greater than the lower limit of the above range, the separation distance between the first surface 1a of the sheet 1 and the adhesive layer 4 and the transparent base material 3 can be sufficiently lengthened. When the arithmetic mean roughness Ra is not more than the upper limit of the above range, the adhesive force of the adhesive layer 4 and the transparent base material 3 with respect to the first surface 1a of the sheet 1 can be sufficiently enhanced.
Here, the arithmetic mean roughness Ra is a value obtained according to JIS B 0601: 2013 (ISO4287: 1997), and is measured by the above-mentioned known microstructure observing means.

The pitch between the adjacent microprojections 5 is not particularly limited, and can be, for example, the same as the pitch between the adjacent through holes 2.
When the pitch between the microprojections 5 and the pitch between the adjacent through holes 2 are about the same, the distance between the first surface 1a of the sheet 1 and the adhesive layer 4 and the transparent base material 3 is set to the microprojections 5. It becomes easy to keep the length of each microprojection 5, and the anchoring of each microprojection 5 to the adhesive layer 4 becomes appropriate, and the adhesive force can be sufficiently enhanced.
The pitch is obtained by the following method. First, for a 1 cm square region randomly selected from the first surface 1a of the sheet 1, 10 or more sets of adjacent microprojections 5 are randomly extracted by known image processing, and each pitch (microprojections) is extracted. Distance between the tops of the image) is measured. This is repeated three times or more, and the average value of the pitches obtained for each is taken as the pitch of the minute protrusions 5 on the first surface 1a of the sheet 1.

<Effect>
In the optical control filter 20 shown in FIG. 2, the separation distance between the first surface 1a of the sheet 1 and the adhesive layer 4 and the transparent base material 3 is determined by the presence of the plurality of microprojections 5 according to the first embodiment. It is longer than that of the optical control filter 10. As a result, even if the adhesive of the adhesive layer 4 flows when stress is applied from the outside, the gap between the microprojections 5 accepts the inflow of the adhesive, so that the adhesive can reach the inside of the through hole 2. It is difficult to reach and is prevented from flowing into the through hole 2.
Further, since the sheet 1 and the microprojections 5 are made of an elastomer, for example, when a stress is applied from the outside by being pressed or bent, the sheet 1 and the microprojections 5 can absorb the stress. .. As a result, it is possible to suppress or reduce a part of the adhesive layer 4 from invading (inflowing) into the through hole 2. Therefore, even if stress is applied to the optical control filter 20 from the outside, excellent optical characteristics are maintained.

Regarding the optical control filter 20 of the second embodiment described above, a plurality of microprojections 5 are formed only on the first surface 1a of the sheet 1, and the transparent base material 3 and the adhesive are adhered only on the first surface 1a side of the sheet 1. The case where the layer 4 is provided has been described. In the optical control filter 20 of the present embodiment, the second surface 1b of the sheet 1 may also be provided with a plurality of microprojections 5, a transparent base material 3, and an adhesive layer 4.

Further, although not shown, the optical control filter 20 of the present embodiment may not include the adhesive layer 4. In this case, it has a structure in which a plurality of microprojections 5 formed on the first surface 1a of the sheet 1 and the transparent base material 3 are joined. If at least one of the contact surfaces (bonding surfaces) of the microprojections 5 on the first surface 1a and the transparent base material 3 is subjected to the above-mentioned surface treatment, they can be easily bonded by pressure bonding or heating.
If the optical control filter 20 does not have the adhesive layer 4, the adhesive layer 4 does not intrude into the through hole 2 even if stress is applied from the outside, and excellent optical characteristics are obtained. Is maintained.

The optical control filter according to the present invention can be used by being attached to an image display device such as a liquid crystal display device for the purpose of controlling the viewing angle, improving the brightness, preventing glare, and the like. More specifically, the optical control filter can be used by being attached to, for example, a light emitting diode, a light emitting body such as an organic electroluminescence element, or a light receiving body such as an optical sensor.

<Manufacturing method of optical control filter>
An example of the method for manufacturing the optical control filter of the present invention will be described by taking the case of manufacturing the optical control filter 10 and the optical control filter 20 as an example.

[Manufacturing process of sheet 1]
First, the elastomer sheet 1 is molded using a molding die having irregularities formed therein. The concave portion of the molding die corresponds to the elastomer portion of the sheet 1, and the convex portion of the molding die corresponds to the through hole 2 of the sheet 1. Elastomer is injected into the molding mold to obtain a sheet 1 to which the unevenness is transferred.
Specifically, as shown in FIG. 4A, a liquid elastomer precursor L containing a light-shielding material is applied to the surface of the molding die K in which the recess M corresponding to the elastomer portion of the sheet 1 is formed. Next, as shown in FIG. 4B, the elastomer precursor L filled in the recess M of the molding die K is cured to form the sheet 1 in the molding die K. At this time, the elastomer precursor L that overflows without entering the recess M becomes a residual film N that covers the first surface 1a of the sheet 1. The sheet 1 is taken out from the molding die K, and the excess residual film N is removed by cutting or polishing (FIG. 4 (c)). If necessary, the thickness of the sheet 1 is adjusted by cutting or polishing the first surface 1a or the second surface 1b of the sheet 1. Further, the size of the sheet 1 in a plan view is cut into a desired size and used.

As a specific method of cutting the residual film N from the sheet 1 or cutting the first surface 1a or the second surface 1b of the sheet 1, a metal blade is inserted along the plane formed on the sheet 1. A method of cutting can be mentioned. When cutting in this way, the opening is deformed and cut due to friction between the openings of the plurality of through holes 2 and the blade, so that the cutting surface including the periphery of the opening (that is, the sheet 1 to be formed) is formed. Microprojections 5 can be formed on the entire first surface 1a or second surface 1b). One of the reasons for the formation of the microprojections 5 is that the blade is slightly vibrated due to friction.
Further, the height and pitch of the microprojections 5 can be adjusted by transmitting the vibration of ultrasonic waves to the metal blade to be cut and adjusting the intensity and frequency of the ultrasonic waves.
FIG. 5A shows a photograph in which microprojections 5 are formed on the cutting surface (first surface 1a) of the silicone rubber sheet 1. The result of measuring the unevenness of the first surface 1a along the white line of the photograph is shown in FIG. 5 (b). From FIG. 5, it can be seen that the weight-shaped microprojections 5 having a height of about 1 μm are formed at regular intervals of about 25 μm pitch by cutting along the surface of the sheet 1 with a metal blade.
The sheet 1 having a smooth surface can be formed by polishing instead of cutting. The sheet 1 having a smooth surface is used for manufacturing the light control filter 10.

(Molding mold K)
The molding die K is a flat plate in which a concave portion for forming an elastomer portion (light-shielding portion) and a plurality of columnar convex portions (non-concave portions) for forming a through hole 2 in the concave portion are formed. The depth of the recess and the height of the protrusion are the same. The pitch between the convex portions corresponds to the pitch between the through holes 2, the height of the convex portions corresponds to the height of the through holes 2, and the diameter (thickness) of the convex portions corresponds to the diameter R of the through holes 2. .. In the molding die K, the axial direction of the central axis of the convex portion and the side surface of the convex portion are arranged perpendicular to the bottom surface of the molding die K. By using such a molding die K, the side surface of the through hole 2 in the obtained sheet 1 can be formed perpendicular to each surface of the sheet 1.

Examples of the method for producing the mold K include a method of forming a recess M by dry etching or wet etching one surface of a flat plate-shaped base material, and a method of cutting one surface of a flat plate-shaped base material to form a recess M. The method of forming is mentioned. Examples of the flat plate-shaped base material include a silicon wafer and a quartz substrate.
Examples of the dry etching include plasma etching, laser etching, ion etching and the like. As a method of plasma etching, a method of forming a recess M by arranging a mask on the surface of a base material, irradiating the surface of the substrate with plasma through the mask, and etching only the surface not covered with the mask can be mentioned. ..

Specific methods for molding the sheet 1 using the molding die include, for example, the following methods (a-1) to (a-5).
(A-1): A liquid elastomer precursor L is applied onto a flat surface of a support film to form a film of the elastomer precursor L, and then the recess M of the molding die K is pressed against the film to form an elastomer. A method of curing the precursor L.
(A-2): A method in which a liquid elastomer precursor L is poured into a recess M of a molding die K, filled in the recess M using a spatula or the like, and then the elastomer precursor L is cured.
(A-3): A liquid elastomer precursor L is applied to the recess M of the molding die K, the applied elastomer precursor L is pressed by a pressing die, the elastomer precursor L is filled in the recess M, and then the elastomer. A method of curing the precursor L.
(A-4): A method in which an elastomer sheet prepared in advance is pressed against a concave portion M of a molding die K while being heated, and unevenness is transferred to a sheet softened by heat.
(A-5): A method of attaching a molding die K to an injection molding machine and injection molding an elastomer.

In the method (a-1), examples of the liquid elastomer precursor L include curable compounds such as curable silicone, isocyanate and polyol. A polymerization catalyst may be added to the elastomer precursor L. When the elastomer precursor L is thermosetting, a thermopolymerization catalyst is added, and when the elastomer precursor L is photopolymerizable, a photopolymerization catalyst is used. Further, the above-mentioned light-shielding material may be added to the elastomer precursor L. If a light-shielding material is added, the elastomer portion has sufficient light-shielding properties. If necessary, other components such as a solvent may be further mixed with the elastomer precursor L (the same applies to the following method).

As the support film, a film that can be easily peeled off from the obtained sheet 1 is preferable, and examples thereof include a polyethylene terephthalate film and a polypropylene film. Examples of the method of applying the elastomer precursor L to the support film include a method using a known coater. The amount of the elastomer precursor L applied on the support film is adjusted to a sufficient amount for producing the target sheet 1.
By pressing the recess M of the molding die K against the film of the elastomer precursor L formed on the support film, the recess M is filled with the elastomer precursor L, and the uneven shape is formed on the film. Examples of the method for thermosetting the elastomer precursor L include a method of heating the molding die K pressed against the film and a method of heating using an external heater provided separately from the molding die K. When the elastomer precursor L is photocured, it can be photocured by, for example, irradiation with ultraviolet rays or an electron beam.
The sheet 1 can be formed by curing the elastomer precursor L.

In the method (a-2), the amount of the elastomer precursor L flowing down onto the recess M of the molding die K is adjusted to the amount at which the target sheet 1 can be obtained.
After the liquid elastomer precursor L is poured onto the recess M of the molding die K, the surface of the elastomer precursor L is leveled with a spatula or the like to fill the recess M with the elastomer precursor L. Then, the elastomer precursor L is cured to form the sheet 1. As the curing method, the same method as in (a-1) described above can be adopted.

As a method of applying the elastomer precursor L in the method (a-3), for example, the elastomer precursor is pressed by pressing a pressing die against the liquid elastomer precursor L adhering to an arbitrary position of the recess M of the molding die K. A method of stretching the body L and filling the recess M with the elastomer precursor L can be mentioned. Moreover, you may adopt a known coater as the coating method. As the curing method, the same method as in (a-1) described above can be adopted.

The method (a-4) is a press molding method using a known press molding machine. The sheet 1 can be formed by attaching the molding die K to the press molding machine and press molding the elastomer. The elastomer may contain the light-shielding material and other components.
The method (a-5) is an injection molding method using a known injection molding machine. The sheet 1 can be formed by attaching the molding die K to the injection molding machine and molding the elastomer. The elastomer may contain the light-shielding material and other components.

In the methods (a-1) to (a-5), when the sheet 1 is formed in the recess M of the molding die K, the elastomer precursor L that overflows without entering the recess M becomes the residual film N. ..
As an advantage of forming the residual film N, when the elastomer precursor L is cured, the shape of the edge of the opening of the recess M (the shape of the tip of the convex portion) is the shape of the opening of the through hole 2 of the sheet 1 to be formed. It can be easily reflected in the shape, that is, the through hole 2 reflecting the shape of the recess M can be formed with high accuracy.

As a method of removing the excess residual film N after curing, in addition to the method of cutting a metal blade along the sheet plane as described above, for example, a contact type known for cutting or polishing the surface of a general substrate. Examples thereof include non-contact known methods such as methods, laser processing, and plasma processing.

Since the sheet 1 has flexibility and elastically deforms, it is relatively easy to remove the sheet 1 from the molding die K, and it is possible to prevent the unevenness of the molding die K from being damaged during the removal.
Further, since the shape of the through hole 2 possessed by the sheet 1 removed from the molding die K corresponds to the shape of the convex portion of the molding die, the shape of the opening of the first surface 1a and the second surface of the through hole 2 It is easy to make the shape of the opening of 1b the same. For example, if the shape of the convex portion of the molding die is made cylindrical, the shape of the openings of the first surface 1a and the second surface 1b of the through hole 2 can be made circular with the same diameter.

[Attachment of transparent base material 3]
As shown in FIG. 6, the target optical control filter can be obtained by attaching the transparent base material 3 to the first surface 1a of the sheet 1.
As an example, a pressure-sensitive adhesive can be applied to the surface of the transparent base material 3 on the sheet 1 side in advance to form a pressure-sensitive adhesive layer 4, and the transparent base material 3 can be attached via the pressure-sensitive adhesive layer 4. The adhesive layer 4 can be formed by a known method.
As another example, at least one of the first surface 1a having the microprojections 5 of the sheet 1 and the attachment surface of the transparent base material 3 is subjected to a known surface treatment and directly attached without interposing the adhesive layer 4. You can also do it. At this time, it can be attached by a known method such as crimping or heating.

By the way, as shown in FIG. 7, a step S may be unintentionally formed on the first surface 1a of the sheet 1 to which the transparent base material 3 is attached. When the first surface 1a is cut or polished, a step S may be formed when the opening of the through hole 2 is caught or caught. The height difference (gap length) of the step S can be, for example, 0.1 μm to 3 μm. Two manufacturing examples using the sheet 1 having the step S will be described below.

As an example, as shown in FIG. 7, when the transparent base material 3 is attached to the smooth first surface 1a having the step S, as shown in FIG. 8, the high portion of the first surface 1a (the portion where the sheet 1 is thick). The pressing force applied to (arrows a and b in the figure) is larger than the pressing force (arrows c and d in the figure) applied to the lower portion (the portion where the sheet 1 is thin) of the first surface 1a. As a result, the through hole 2 in the thick portion of the sheet 1 is deformed, and the light transmission in the through hole 2 may be different from the transmission in the other through holes 2 and non-uniformity may occur.

As another example, when the transparent base material 3 is attached to the first surface 1a having a step S and having a plurality of microprojections 5 as shown in FIG. 9, the first surface 1a is high as shown in FIG. The tip of the microprojection 5 in the portion (thick portion of the sheet 1) is deformed or bites into the adhesive layer 4, and the tip of the microprojection 5 in the lower portion of the first surface 1a (the portion where the sheet 1 is thin) is viscous. It is in contact with the surface 4b of the adhesive layer 4. Further, the step S on the first surface 1a is substantially maintained. As described above, as a result that the influence of the step S is almost eliminated by the minute protrusions 5, the through hole 2 in the thick portion of the sheet 1 is not deformed as in the above example, and the uniformity is maintained. This example is a preferable example showing the advantage of manufacturing the light control filter 20 using the sheet 1 having the microprojections 5. Further, the same effect can be obtained not only at the time of manufacturing but also when stress is applied from the outside during use.

In the manufacturing example of the optical control filter described above, the case where the transparent base material 3 is attached to the first surface 1a side of the sheet 1 has been described, but similarly, the transparent base material 3 is also attached to the second surface 1b side of the sheet 1. 3 can be pasted.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
As a molding mold for producing an elastomer sheet of an optical control filter, a recess having a length × width × depth of 20 mm × 20 mm × 180 μm is formed on the surface, and 800 × 800 is formed in the recess along the XY directions. A silicon (Si) molding die was prepared in which convex portions of individual columns (diameter 15 μm, height 180 μm) were arranged in a grid pattern at a pitch of 25 μm.
Further, a liquid thermosetting silicone (KE-1935, manufactured by Shin-Etsu Chemical Co., Ltd.) and carbon black were mixed to obtain a paint for forming a light-shielding portion. The content of the thermosetting silicone with respect to the total mass of the coating material was adjusted to be about 95% by mass with respect to the total mass of the cured product obtained after the coating material was cured.

The paint for forming a light-shielding portion was applied to the surface of a polyethylene terephthalate film to form a thermosetting silicone film.
Next, the surface on which the concave portion M of the molding mold was formed was pressed against the film of the thermosetting silicone, and heated at 130 ° C. for 5 minutes to cure the thermosetting silicone.

Next, after taking out the elastomer sheet from the recess of the molding die, a metal blade is inserted along the plane formed in the elastomer sheet to form a surplus thermosetting silicone that did not enter the recess M. The residual film was removed by cutting.
On the cutting surface of the optical control filter obtained by removing the residual film, microprojections having a pitch of about 25 μm and a height of about 1 μm were formed (see FIG. 5). The arithmetic average roughness Ra of the cutting surface measured in accordance with the JIS standard described above was 0.25 μm, and the average length RSm of the roughness curve element was 24.2 μm.

Using a laminate (thickness: 1080 μm) in which six elastomer sheets are stacked as a test piece, a “micro rubber hardness tester” manufactured by Polymer Meter Co., Ltd., trade name: MD-1capa, is used, and the MD- 1 Rubber hardness was measured in an environment of 23 ° C. according to the above-mentioned measuring method (needle shape: type A, pressure leg size: type A, spring load: 22 mN, measurement mode: normal mode). As a result, the MD-1 rubber hardness was 55.

After corona treatment is performed on the adhesive surface on which the microprojections of the elastomer sheet are formed, the adhesive surface is bonded to a transparent base material made of polyethylene terephthalate via a double-sided tape having an acrylic adhesive having a thickness of 50 μm. did.
In the optical control filter bonded to the transparent base material, the adhesive did not penetrate into the through holes of the sheet, and a good viewing angle control effect was obtained.

When the transparent member of the obtained optical control filter was pressed with a finger, the elastic force of the elastomer sheet dispersed the stress, so that the adhesive did not flow into the through holes of the sheet. As a result, the light transmitted through the through hole of the sheet was not scattered by the adhesive in the through hole, and excellent optical characteristics were obtained.

1 Elastomer sheet 1a First surface 1b Second surface 2 Through hole 3 Transparent base material 4 Adhesive layer 5 Micro protrusions 10 Optical control filter 20 Optical control filter K Molded L Elastomer precursor M Recessed

Claims (5)

An elastomer sheet with multiple through holes in the thickness direction and
An optical control filter comprising, on at least one surface side of the sheet, a transparent substrate that covers the one surface and the openings of the plurality of through holes. The light control filter according to claim 1, wherein the transparent base material is attached to one of the surfaces via an adhesive layer. At least one of the contact surface of the sheet with respect to the transparent base material and the contact surface of the transparent base material with respect to the sheet is surface-treated, and the sheet and the transparent base material do not pass through an adhesive layer. The optical control filter according to claim 1, which is joined to. The optical control filter according to any one of claims 1 to 3, wherein microprojections are provided on at least one surface of the sheet, including the periphery of the openings of the plurality of through holes. Microprojections are provided on at least one surface of the sheet, including around the openings of the plurality of through holes.
The optical control filter according to claim 2, wherein at least a part of the microprojections bites into the adhesive layer.

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