JP7162575B2 - Optical filter manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an optical filter.

2. Description of the Related Art Conventionally, light control films for adjusting light transmittance and viewing angle are known. For example, in Patent Document 1, a photocurable resin containing a light absorbing material is provided as a base film, and a plurality of mortar-shaped recesses are formed from one main surface of the base film toward the other main surface on the opposite side. Formed light control films have been proposed. In the manufacturing process of the light control film, the microstructured layer with a large number of concave portions is formed by pouring a photocurable resin into a mold having convex portions corresponding to the concave portions, curing the resin, and then releasing the mold. It is formed.

JP 2017-54129 A

In order to increase the arrangement density of the concave portions of the microstructured layer of the light control film of Patent Document 1 and to increase the aspect ratio (depth/diameter) of the concave portions, the convex portions of the mold used in the manufacturing process are There is a need to increase the density and increase its aspect ratio (height/diameter). However, when a hardening resin is poured into a mold with a dense array of long and narrow projections (microprotrusions) and then released from the mold after curing, the microprotrusions of the mold crack or chip. There's a problem.

INDUSTRIAL APPLICABILITY The present invention provides a method capable of manufacturing an optical filter having fine through-holes at high density without using a mold.

[1] Arranging a plurality of wires in one direction on the first surface of the first resin layer at arbitrary intervals; Forming a resin layer to form a wire-containing sheet; obtaining a laminate in which a plurality of the wire-containing sheets are laminated with the wires aligned with each other; Obtaining a sliced sheet by slice cutting, and removing all or part of the plurality of wires penetrating in the thickness direction of the sliced sheet to form a plurality of penetrating portions penetrating in the thickness direction of the sliced sheet obtaining an optical filter with pores.
[2] The method for manufacturing an optical filter according to [1], wherein removing the wire is to dissolve the wire by bringing a solution into contact with the wire.
[3] After obtaining the sliced sheet, disposing a masking body on one main surface and a part of the other main surface of the sliced sheet; forming a through-hole region having a plurality of through-holes penetrating in the thickness direction of the sliced sheet by removing the plurality of wires, and then removing the masking body so that the wires remain The method for producing an optical filter according to [1] or [2], comprising obtaining the optical filter in which a non-penetrating region is formed.
[4] Forming a thin layer portion in the sliced sheet by removing a part of the sliced sheet in the thickness direction from at least one main surface side of the sliced sheet, [1] to [3] The method for producing an optical filter according to any one of 1.
[5] Forming a thin layer portion in the optical filter by removing part of the optical filter in the thickness direction from at least one main surface side of the optical filter, [1] to [3] The method for producing an optical filter according to any one of 1.
[6] The method for producing an optical filter according to any one of [1] to [5], wherein the first resin layer and the second resin layer are elastomers.
[7] The method for producing an optical filter according to any one of [1] to [6], wherein the first resin layer and the second resin layer contain a light shielding material.
[8] The method for producing an optical filter according to any one of [1] to [7], wherein the wire is a metal wire.
[9] Arranging a plurality of wires in one direction on the first surface of the first resin layer at arbitrary intervals; forming a resin layer to form a wire-containing sheet; obtaining a laminate in which a plurality of the wire-containing sheets are laminated with the wires oriented in the same direction; and all of the plurality of wires included in the laminate. Alternatively, by removing a part of the block body, a plurality of through holes or a plurality of non-through holes corresponding to the wires are formed in the laminate, and the plurality of through holes of the block body are obtained. Alternatively, obtaining an optical filter having a plurality of through-holes penetrating in a thickness direction by slice-cutting in a direction transverse to the longitudinal direction of the plurality of non-through-holes.
[10] One end of the plurality of wires protrudes from one surface of the laminate, and the block is obtained by gripping the end and pulling out the plurality of wires from the laminate, [ 9].

According to the method for manufacturing an optical filter of the present invention, an optical filter having fine through holes at high density can be manufactured without using a mold.

It is a perspective view which shows the outline of an example of the manufacturing method of an optical filter. 2 is a perspective view showing an optical filter 10; FIG. 2 is a cross-sectional view of the optical filter 10 of FIG. 1 taken along the X-axis near the center thereof; FIG. 2 is a partial top view of the optical filter 10 of FIG. 1; FIG. 2 is a top view of an optical filter 20; FIG. 3 is a cross-sectional view of the optical filter 30 cut along the X-axis; FIG.

<First aspect>
In the first aspect of the present invention, a plurality of wires are aligned in one direction and arranged at arbitrary intervals on the first surface of the first resin layer (arranging step), and on the first surface of the first resin layer, forming a second resin layer covering the plurality of wires to form a wire-containing sheet (a step of forming a wire-containing sheet); Obtaining (laminate forming step), obtaining a sliced sheet (sliced sheet forming step) by slice-cutting in a direction across a plurality of conductive lines of the laminate (sliced sheet forming step), and thickness direction of the sliced sheet removing all or part of the plurality of wires penetrating through the sliced sheet to obtain an optical filter having a plurality of through holes penetrating in the thickness direction of the sliced sheet (a wire removing step). manufacturing method.
Hereinafter, examples of embodiments of each step will be described with reference to the drawings.

[Placement process]
As illustrated in FIG. 1A, a plurality of wire rods S are aligned in one direction and arranged parallel to each other at arbitrary intervals on the first surface 110a of the first resin layer 110 formed on the substrate 100. Deploy.
In this example, the longitudinal direction of each wire S is arranged perpendicular to the longitudinal direction of the base material 100 . Here, one principal surface of the first resin layer 110 is called the first surface, and the other principal surface is called the second surface.

The intervals between the plurality of wire rods S may be constant or random. The center-to-center distance between two adjacent wires S is not particularly limited, and is appropriately adjusted according to the application of the optical filter. The arrangement of the wire rods S corresponds to the arrangement of through holes to be formed in a later process. That is, the center-to-center distance between two adjacent wires S corresponds to the center-to-center distance between two adjacent through holes. Therefore, the smaller the distance between the wire rods S, the higher the density of the arrangement of the through holes.
The center-to-center distance can be, for example, 6 μm to 1,000 μm, and can be, for example, 6 μm to 50 μm when high density is intended.

The material of the wire rod S is not particularly limited as long as it does not integrate with the first resin layer, and examples thereof include metal, glass, ceramic, synthetic resin, natural resin, and paper. Among these, materials that can be removed by wet etching in a post-process are preferred, metals or synthetic resins are more preferred, and metals are even more preferred. Examples of metals include iron, copper, aluminum, lead, zinc, tin, tungsten, etc., which can be removed with a solution containing nitric acid.
Engineering plastics such as polyamide, PEEK, and liquid crystal polymer are preferable as the synthetic resin.

The shape of the cross section of the wire rod S cut perpendicular to the longitudinal direction is not particularly limited, and examples thereof include circular, elliptical, triangular, square, rectangular, and polygons with pentagons or more.
The diameter (outer diameter) of the wire S is not particularly limited, and can be, for example, 5 μm to 300 μm. If the shape of the cross section is other than circular, the diameter of the wire S is the diameter of the smallest circle that includes the cross section.

The wire S may be a composite wire having a core wire and a coating layer formed on the outer peripheral surface of the core wire. In the wire removing step, by leaving the covering layer and removing only the core wire from the composite wire, the covering layer can form the inner wall of the through hole. The coating layer may be two or more layers, and the material constituting each coating layer may be the same or different.

Examples of the core wire include those made of base metals such as iron, copper, aluminum, lead, zinc, tin and tungsten, and resins such as polyvinyl alcohol. A core wire made of a base metal can be removed by bringing it into contact with a solution containing nitric acid. A core wire made of a resin such as polyvinyl alcohol can be removed by bringing it into contact with a solution made of water or an organic solvent.

The coating layer is preferably one that is difficult to dissolve even in contact with the solution. Examples include metals such as gold, platinum, silver, copper, nickel, rhodium, palladium, and black ruthenium, and alloys of these metals. be done. Among them, gold, platinum, silver and copper with high standard electrode potential are more preferable, and gold and silver with low hardness are more preferable.
By having the coating layer, contact between the core wire and the first resin layer 110 and the second resin layer 120 can be avoided. For example, a core wire containing sulfur, phosphorus, a nitrogen compound, tin, or the like can be prevented from inhibiting curing (vulcanization) of the first resin layer 110 or the second resin layer 120 made of silicone.

The shape of the cross section of the composite wire rod cut perpendicular to the longitudinal direction is not particularly limited, and examples thereof include circular, elliptical, triangular, square, rectangular, and polygons with pentagons or more.
The diameter (outer diameter) of the composite wire is not particularly limited, and can be, for example, 5 μm to 300 μm. If the shape of the cross section is other than circular, the diameter of the composite wire is the diameter of the smallest circle that includes the cross section.
The diameter (outer diameter) of the core wire of the composite wire is not particularly limited, and can be, for example, 1 μm to 200 μm. If the shape of the cross section is other than circular, the diameter of the core wire is the diameter of the smallest circle that includes the cross section.

In the present specification, the diameter of a wire is an average value obtained by measuring the diameters of five or more randomly selected wires with an enlarged observation means such as a microscope.

As the base material 100, a material that can be easily peeled off from the wire containing sheet is used as necessary, and examples thereof include a resin film such as polyethylene terephthalate (PET).
The resin constituting the first resin layer 110 is not particularly limited, and known resins can be applied, and it may be either a thermoplastic resin or a thermosetting resin. From the viewpoint of facilitating arrangement of the wire S, the surface of the first resin layer 110 preferably has tackiness (adhesiveness), and the resin is more preferably an elastomer.

Examples of the elastomer include thermosetting elastomers such as urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, styrene butadiene rubber, acrylonitrile-butadiene rubber, and silicone rubber; urethane, ester, and styrene olefin-based, butadiene-based or fluorine-based thermoplastic elastomers; or composites thereof. Among these, silicone rubber is preferable because it has tackiness, low compression set, high heat resistance, and excellent weather resistance and cold resistance.

The first resin layer 110 preferably contains a light shielding material. Light-shielding materials are roughly classified into light-absorbing materials and light-reflecting materials.
Examples of light-absorbing materials include carbon, dyes, and pigments. Among these, carbon is preferable because it is excellent in light absorption. Examples of carbon include carbon black, graphite, and carbon fiber.
Light reflective materials include, for example, metals. Metals include aluminum, silver, gold, chromium, nickel and the like.

Examples of the method of forming the first resin layer 110 on the substrate 100 include a method of attaching a sheet-like first resin layer 110 onto the substrate 100, a method of applying a liquid resin material onto the substrate 100, Examples thereof include a method of curing the formed coating film.
The method of attaching the sheet-like first resin layer 110 onto the base material 100 is not particularly limited, and includes a method using an adhesive, a method of activating the attachment surface by surface treatment such as excimer treatment and corona treatment, and bonding. is mentioned.

The thickness of the first resin layer 110 can be, for example, 0.5 μm to 500 μm. The thinner the thickness, the higher the arrangement density of the wires in the stacking direction of the wire-containing sheets in the block body in the post-process.

The method of arranging the wire S on the first surface 110a of the first resin layer 1000 is not particularly limited, and for example, the first surface of the first resin layer 110 continuously formed on the sheet-like substrate 100 unwound from a roll. There is a method in which a plurality of wire rods S wound around bobbins are let out from the surface 110a and arranged continuously on the first surface 110a of the first resin layer 110 at a constant pitch.

[Step of forming sheet containing wire]
As illustrated in FIG. 1B, the second resin layer 120 is formed on the first surface 110a of the first resin layer 110 on which the plurality of wires S are arranged, and the second resin layer 120 and the first resin By integrating the layers 110 , the wire S is fixed between the first resin layer 110 and the second resin layer 120 to form the wire containing sheet 130 .

Examples of the resin constituting the second resin layer 120 are the same as those of the first resin layer 110 . The resin constituting the second resin layer 120 may be the same as or different from the resin constituting the first resin layer 110, but from the viewpoint of improving the adhesion between the two layers, the resin should be the same. is preferred. Like the first resin layer 110, the second resin layer 120 preferably contains a light shielding material.

The method of forming the second resin layer 120 on the first surface of the first resin layer 110 includes the same method as the method of forming the first resin layer 110 on the substrate 100 .
The thickness of the second resin layer 120 is not particularly limited, and can be, for example, 0.5 μm to 500 μm. The thickness of the second resin layer 120 may be the same as or different from the thickness of the first resin layer 110 .

[Laminate forming step]
As exemplified in FIG. 1C, a laminate 140 is formed by laminating a plurality of wire-containing sheets 130 . At the time of lamination, the directions of the wires S of the respective wire containing sheets 130 are aligned with each other. At this time, it is preferable that the wire rods S are aligned and laminated so that the positions of the wire rods S overlap when viewed in the stacking direction of the laminate 140 . In the illustrated example, the case where all the wire rods S are overlapped when viewed in the stacking direction is illustrated, but some of the wire rods S may not be overlapped.

In this step, the unnecessary base material 100 is peeled off from each wire-containing sheet 130 before laminating each wire-containing sheet 130 . In the illustrated example, the base material 100 is left only on the lowermost wire-containing sheet 130 . Further, another resin layer forming the upper surface 140a of the laminate 140 is further laminated.

Examples of the method of laminating the wire-containing sheets 1300 include a method of bonding each wire-containing sheet using an adhesive, and a method of bonding by activating the lamination surface of the wire-containing sheet 130 by surface treatment.
The adhesive may be the same type of resin as the resin forming the first resin layer 110 and the second resin layer 120, or may be a different type of resin.

[Slice sheet forming process]
As illustrated in FIG. 1(d), the laminate 140 is sliced to obtain a sliced sheet 150 having a desired thickness in which the cut surface of the wire rod S is exposed. At the time of slice cutting, the cut surfaces of the wires S included in the laminate 140 can be exposed on the surface of the slice sheet 150 by cutting across the longitudinal direction of the plurality of wires S included in the laminate 140 .
Examples of methods for slice-cutting the laminate 140 include methods such as laser processing and cutting.
The thickness of the slice sheet 150 corresponds to the thickness of the intended optical filter, and is appropriately set according to the application of the optical filter, and can be, for example, 30 μm to 5000 μm.

[Wire removal step]
A plurality of wires S of the sliced sheet 150 penetrate through the sliced sheet 150 in the thickness direction. By removing all or part of these wires S, it is possible to obtain the optical filter 10 in which the through holes 51 are formed at the locations where the wires S have been removed (see FIGS. 2 to 4).

A method for removing the wire S from the sliced sheet 150 is selected according to each material forming the first resin layer 110, the second resin layer 120, and the wire S. As shown in FIG.
When the adhesion between the wire rod S and the sliced sheet body is weak, the wire rod S can be removed from the sliced sheet body by, for example, vibrating, bending, or hitting the sliced sheet 150 . When the adhesion strength is moderate, the wire S included in the sliced sheet 150 can be pulled out and removed. When the adhesion is strong, a method of dissolving the wire rods S by contacting the wire rods S contained in the sliced sheet 150 with a dissolving liquid is preferable.

When the material of the wire S is, for example, a base metal such as iron, copper, aluminum, lead, zinc, tin, or tungsten, the wire S is removed by wet etching using a solution containing nitric acid to form the through hole 51. can do. Specifically, for example, the wire S can be dissolved by immersing the slice sheet 150 in a solution.
Moreover, when the wire S is made of an organic substance such as polyvinyl alcohol, a solution containing water or an organic solvent capable of dissolving the organic substance can be used.
The temperature of the solution when the wire S is melted is, for example, 10 to 100.degree.

When the wire rod S is the composite wire rod described above, only the core wire rod may be dissolved and the coating layer may remain on the sliced sheet main body. In this case, a through hole is formed at the location where the core wire is removed, and the coating layer forms the inner wall of the through hole.
When the coating layer is made of metal, the light incident on the through-hole passes through the through-hole while being reflected by the coating layer, and is hardly absorbed in the through-hole. can be improved.

[masking]
A method of arranging the masking bodies on a part of one main surface 150a and the other main surface 150b of the sliced sheet 150 will be described. The masking body protects the wire S included in the sliced sheet 150 . After the masking body is placed, the wire rod S removal step described above is performed, whereby the wire rod S is removed in the region A where the masking body is not placed, and the wire rod S is left in the region B where the masking body is placed. be able to. As a result, in the region A, a through-hole region having a plurality of through-holes passing through the sliced sheet 150 in the thickness direction is formed, and in the region B, the wire rod S remains by removing the masking body. Non-penetrating regions can be formed. That is, by arranging the masking body in a desired region, an optical filter having a through hole region and a non-penetrating group can be obtained.

The masking body is not particularly limited as long as it is made of a material that is difficult to dissolve in the solution and can adhere to the main surface of the slice sheet 150. Examples thereof include a masking tape, a resist layer, and a glass plate.

[Formation of thin layer]
A thin layer portion may be formed in the sliced sheet 150 by removing a part of the sliced sheet 150 in the thickness direction from at least one main surface side of the sliced sheet 150 obtained in the sliced sheet forming step. Thereafter, by removing the wire rod S in the removing step, the optical filter 1 partially provided with a thin layer portion can be obtained.
Alternatively, a thin layer portion may be formed in the optical filter 1 by removing a part of the optical filter 1 in the thickness direction from at least one main surface side of the optical filter 1 obtained in the wire removing step.
As a method for removing a part of the slice sheet 150 and the optical filter 1 in the thickness direction, known resin film processing techniques such as grinding, cutting, laser processing, etc. can be applied.

The production method of the first aspect described above is performed in the order of removing the wire rods contained in the sliced sheet after obtaining the sliced sheet, but the production method of the second aspect that does not follow this order is performed. good too.

<Second mode>
In a second aspect of the present invention, a plurality of wires are aligned in one direction and arranged at arbitrary intervals on the first surface of the first resin layer (arranging step), and on the first surface of the first resin layer, forming a second resin layer covering the plurality of wires to form a wire-containing sheet (a step of forming a wire-containing sheet); obtaining (laminate forming step), and removing all or part of the plurality of wires included in the laminate to form a plurality of through holes or a plurality of non-through holes corresponding to the wires in the laminate is formed (block body forming step), and by slice cutting in a direction transverse to the longitudinal direction of the plurality of through holes or the plurality of non-through holes of the block body, the thickness Obtaining an optical filter having a plurality of through-holes penetrating in a direction (cutting step).

[Arranging process], [Wire containing sheet forming process], [Laminate forming process]
The above three steps can be performed in the same manner as the steps of the first aspect.
It is preferable that one end of a plurality of wires protrude from one surface of the laminate obtained in this embodiment. As a method for obtaining such a laminate, in the arrangement step, one end of a plurality of wires S arranged on one main surface of the first resin layer 110 is protruded from an arbitrary side of the first resin layer 110. There is a method of arranging. By forming the second resin layer 120 in the subsequent wire-containing sheet forming step, a wire-containing sheet in which one end of each wire S protrudes from one side of the sheet can be obtained. In the subsequent laminate forming step, by laminating wire-containing sheets in which one end of each wire S protrudes, a laminate in which one end of each wire S protrudes can be obtained. As such a laminate, for example, there is a laminate in which one end of each wire rod S protrudes toward the front side of the paper surface of FIG. The other end of each wire rod S may protrude from the surface on the depth side of the paper surface (the surface on the opposite side of one surface).

[Block body forming step]
As a method of removing each wire rod S from the laminate to obtain a block body, the same method as the wire rod removing step of the first embodiment can be used.
When one end of each wire S protrudes from one surface of the laminate, the block can be obtained by grasping the protruding end and pulling out each wire S from the main body of the laminate.
A plurality of through-holes or a plurality of non-through-holes corresponding to the positions where the wires S were present are formed in the obtained block body. When both ends of each wire S in the laminate protrude from the main body of the laminate, a through hole is formed at the location where the wire S is removed. If only one end of each wire S in the laminate protrudes from the laminate body, a non-through hole is formed at the location where the wire S is removed.
The wire rod S may be left without being removed in the portions of the block where the through holes and the non-through holes are not desired to be formed. The method of leaving the wire S can be performed in the same manner as in the first aspect.

[Cutting process]
As a method of slice-cutting the plurality of through-holes or the plurality of non-through-holes of the block body to a desired thickness in a direction crossing the longitudinal direction, the same method as the sliced sheet forming step of the first embodiment can be mentioned. be done.
Through this process, an optical filter having a desired thickness and having a plurality of through-holes penetrating in the thickness direction can be obtained. If necessary, a thin layer portion may be formed in the same manner as in the first mode.

<Other processing>
In short, the optical filter 1 obtained by each of the above embodiments is a resin sheet in which a plurality of through holes are formed in the thickness direction.
When the resin sheet main body contains a light shielding material, the light incident on the main surface of the optical filter 1 passes through the through holes 51 .
The surface of the resin sheet body may be coated with a light shielding layer such as a metal plating layer or a paint layer. In this case as well, the light incident on the main surface of the optical filter 1 passes through the through holes 51 . A transparent member may be installed inside the through hole 51 . Such a transparent member can be formed, for example, by injecting a transparent resin into the through holes 51 and curing the resin.
On the other hand, if the resin sheet main body does not contain a light shielding material, by installing a light shielding member in the through hole 51, an optical filter that allows light to pass through only the resin sheet main body can be obtained. Examples of the light shielding member include a resin member containing a light shielding material. Such a resin member can be formed by injecting a resin composition containing a light shielding material into the through holes 51 and curing the resin composition.
Examples of embodiments of the optical filter obtained by the manufacturing method of the present invention are described below.

《Optical filter》
The optical filter obtained by the manufacturing method of the present invention is a sheet having a sea-island structure consisting of a light transmitting portion and a light shielding portion, and the light transmitting portion and the light shielding portion extend from the first principal surface to the second principal surface. one of the light transmitting portion and the light shielding portion forms a plurality of island portions penetrating from the first main surface to the second main surface, and the other forms a plurality of island portions extending from the plurality of It forms a sea part that separates the island parts from each other. That is, the main body of the optical filter is a resin sheet, a single sea portion forms the resin sheet, and a plurality of island portions form a plurality of penetrating regions penetrating the resin sheet in the thickness direction.

<First embodiment>
The optical filter 10 illustrated in FIGS. 2-4 extends between a first major surface 1 and an opposite second major surface 2 and between the first major surface 1 and the second major surface 2. A light transmitting portion 3 and a light shielding portion 4 extending between the first main surface 1 and the second main surface 2 are provided. The light transmitting portion 3 and the light shielding portion 4 form a sea-island structure. The light transmitting portion 3 forms a plurality of island portions 5 penetrating from the first main surface 1 to the second main surface 2, and the light shielding portion 4 which does not form the island portions 5 separates the plurality of island portions 5 from each other. It forms a sea portion 6 that allows The main body of the optical filter 10 is made of resin such as elastomer.

The optical filter 10 is in the form of a rectangular sheet, and its longitudinal direction is the X direction, its lateral direction is the Y direction, and the direction perpendicular to its main surface (that is, the thickness direction of the sheet) is the Z direction.
The shape of the optical filter 10 in plan view is not limited to a rectangle, and may be circular, elliptical, polygonal, or any other shape.
The length×width size of the optical filter 10 is not particularly limited, and can be, for example, 5 mm×5 mm to 100 cm×100 cm.

The thickness of the optical filter 10 is, for example, preferably 30 μm or more and 5000 μm or less, more preferably 50 μm or more and 1000 μm or less, and even more preferably 70 μm or more and 500 μm or less.
When the thickness is equal to or greater than the lower limit value, it becomes easier to control the transmission angle of light. If the said thickness is below the said upper limit, flexibility will become higher.
The thickness of the optical filter 10 is obtained as an average value of values measured at ten or more randomly selected locations on the cross section. A well-known microstructure observation means such as a measuring microscope is applied for the measurement.

The optical filter 10 has a sea-island structure formed by a plurality of light transmitting portions 3 (island portions 5) and light shielding portions 4 (sea portions 6).
The main body of the optical filter 10 is a sheet, and one surface of the sheet is called a first main surface 1 and the other surface is called a second main surface 2 .
The total area of the sea portion 6 with respect to the total area of the first main surface 1 is preferably 30-99%, more preferably 50-95%, even more preferably 65-90%. The total area of the sea portions 6 on the second major surface 2 is also preferably the same as the total area of the sea portions 6 on the first major surface 1 .
The total area of each principal surface of the island portion 5 and the sea portion 6 can be obtained by subjecting the photographed images of the respective principal surfaces to image processing by a known method.

The light transmittance of the light transmitting portion 3 is preferably 70% or higher, more preferably 80% or higher, and even more preferably 90% or higher. The light transmittance of the light transmitting portion 3 may be 100%. When the light transmittance is equal to or higher than the above lower limit, the amount of light passing through the optical filter 10 becomes sufficient.
The light transmittance of the light shielding portion 4 is preferably less than 70%, more preferably less than 50%, still more preferably less than 30%, and particularly preferably less than 10%. The light transmittance of the light shielding portion 4 may be 0%. When the light transmittance is less than the upper limit, the optical filter 10 can sufficiently control the light transmission angle.
For example, the light transmittance of the light transmitting portion 3 is preferably 70% or more and 100% or less, and the light transmittance of the light shielding portion 4 is preferably 0% or more and less than 70%, and the light transmittance of the light transmitting portion 3 is 80%. It is more preferable that the light transmittance of the light shielding portion 4 is 0% or more and less than 50%, and the light transmittance of the light transmitting portion 3 is 90% or more and 100% or less, and the light transmittance of the light shielding portion 4 More preferably, the ratio is 0% or more and less than 30%.
Here, the value of the "light transmittance" is obtained by using D65 defined in JIS Z 8720: 2012 as a light source and measuring the intensity of the inspection light emitted from the light source with a light receiving sensor. A is the output value of the light-receiving sensor when there is no object to be measured on the path. A is the output when the object to be measured is set on the optical path of the inspection light and the light transmitted through the object is received by the light-receiving sensor. When the value is B, the value is obtained by light transmittance=(B/A)×100 (unit: %).

(Light transmission part)
The light transmitting portion 3 of the optical filter 10 is the island portion 5 of the sea-island structure, and is a plurality of cylindrical transparent portions separated from each other by the sea portion 6 . Each island 5 passes through the optical filter 10 so that a first end of each island 5 is exposed on the first main surface 1 of the optical filter 10 and a second end of each island 5 is , are exposed on the second main surface 2 of the optical filter 10 . Each island portion 5 is arranged at a constant pitch along the X and Y directions.

The three-dimensional shape of the island portion 5 passing through the optical filter 10 in the Z direction is preferably columnar. Here, that the island portion 5 has a columnar shape means that, assuming that the island portion 5 is taken out from the optical filter 10, the island portion 5 is recognized as a three-dimensional columnar shape. The columnar height direction is along the thickness direction of the optical filter 10 . The top surface (top surface) and bottom surface of the columnar column are parallel to the first main surface 1 and the second main surface 2, respectively.
The cross-sectional shape obtained by cutting the island portion 5 along the XY plane includes, for example, circular, elliptical, quadrangular, and other polygonal shapes. The cross-sectional shape of the first end exposed on the first main surface 1 of the island portion 5 (planar shape on the first main surface 1 of the island portion 5) and the second end portion exposed on the second main surface 2 The cross-sectional shapes of the end portions (planar shapes on the second main surface 2 of the island portion 5) may be the same or different, but are preferably the same from the viewpoint of ease of light control.

The axis of the central axis of the columnar island portion 5 may be perpendicular to the first main surface 1 and the second main surface 2, or may be inclined to facilitate manufacture and control the light transmission angle. From the viewpoint of ease of installation, it is preferably substantially vertical. Here, "substantially perpendicular" means intersecting at 90°±2°. When substantially vertical, the height H of the columnar island portion 5 is approximately the same as the thickness of the optical filter 10 .
The angle between the axis and the main surface and the height H of the island portion 5 can be determined by measuring a cross section including the island portion 5 and the main surface with a known fine structure observation means such as a measuring microscope. The height H of the island portion 5 is the distance between the first principal surface 1 and the second principal surface 2 .

For each island portion 5, the size R of the edge exposed on each major surface is the diameter of the smallest circle containing said edge. The diameter is preferably, for example, 5 μm to 300 μm, more preferably 10 μm to 100 μm, from the viewpoint of easiness in controlling the transmission angle of light passing through the optical filter 10 . When the diameter is equal to or greater than the above lower limit, removal of the wire rod S during manufacturing becomes easier. When the diameter is equal to or less than the above upper limit, the aspect ratio, which will be described later, can be increased.
The sizes R of the two ends exposed on each major surface of the single island portion 5 may be the same or different.
The average diameter of 10 or more island portions 5 randomly selected from the plurality of island portions 5 on any principal surface of the optical filter 10 is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.
The said diameter can be measured by well-known microstructure observation means, such as a measuring microscope.

The aspect ratio represented by (size R: height H) of the columnar island portion 5 is preferably 1:5 to 1:90, more preferably 1:8.5 to 1:60.
When the aspect ratio is 1:5 to 1:90 and the island portion 5 is hollow, the light transmission angle θ is 22.6° to 1.2°. When the aspect ratio is 1:8.5 to 1:60, the light transmission angle θ is 13.4° to 1.8°. Also, when the island portion 5 is filled with a transparent material, the refractive index of the transparent material is generally higher than that of air, so the light transmission angle θ is wider than the range in the hollow case shown above. Therefore, from the viewpoint of narrowing the light transmission angle θ, the island portion 5 is preferably hollow.
When the light transmission angle .theta.
If the light transmission angle .theta. Moreover, it can be manufactured relatively easily.
The aspect ratio is the average value obtained by measuring the size R of both ends and the average value obtained by measuring the height H of ten or more island portions 5 randomly selected from the plurality of island portions 5 of the optical filter 10. It is the ratio to the value. The individual size R and height H can be measured using known microstructure observation means such as a measuring microscope.

The pitch P of the arrangement of the island portions 5 on the first major surface 1 and the second major surface 2, ie the pitch P between adjacent ends of the island portions 5 exposed on each major surface, includes the individual ends. It is the center-to-center distance between the smallest circles. The pitch P is preferably, for example, 6 μm to 1000 μm, more preferably 10 μm to 500 μm, even more preferably 15 μm to 300 μm, from the viewpoint of easiness in controlling the transmission angle of light passing through the optical filter 10 .
When the pitch P is equal to or greater than the above lower limit, the arrangement of the wire rods S during manufacturing is facilitated.
When the pitch P is equal to or less than the upper limit, the visibility of the image seen through the optical filter 10 is enhanced, and sufficient resolution can be easily obtained.
The pitch P is preferably constant on each major surface. The pitch P between the main surfaces may be the same or different.
The pitch P is obtained by subjecting an image of an arbitrary principal plane to image processing by a known method.
When the pitch P of an arbitrary principal surface differs depending on the region of the principal surface, the pitch P of three or more consecutive island portions 5 is preferably within the above range, and the pitch P of five or more consecutive island portions 5 is preferably within the above range. is more preferably within the above range, and it is even more preferable that the pitch P of ten or more consecutive island portions 5 be within the above range.

The arrangement of the island portions 5 on the first main surface 1 and the second main surface 2 is a two-dimensional array of X columns and Y rows. The arrangement of the island portions 5 is not limited to this example, and any arrangement pattern may be adopted. In X columns×Y rows, for example, X and Y can each independently be any integer from 10 to 1,000. When a plurality of island portions 5 are arranged in a two-dimensional array, each line segment that connects the centers of adjacent island portions 5 in any column is on one straight line, and adjacent island portions 5 in any row. are on a straight line, and the straight line representing each column and the straight line representing each row intersect each other at about 90°.
The arrangement pattern may be a two-dimensional array, a zigzag pattern, any other pattern, or a random arrangement.

In the two-dimensional array of X columns×Y rows of the island portions 5 of the optical filter 10 shown in FIGS. , and the arrangement direction of the island portions 5 in each row (the direction of the straight line representing each row) is parallel to the Y-direction side forming the outer edge of the optical filter 10 . As a modification, Y rows of a two-dimensional array of X columns.times.Y rows consisting of a plurality of island portions 5 may be arranged not in parallel with the Y-direction sides of the outer edge but in a direction intersecting them. In this case, the X columns of the two-dimensional array are arranged in a direction intersecting rather than parallel to the X-direction side of the outer edge. For example, referring to FIG. 5, when the Y direction of the outer edge of the optical filter 20 is represented by a straight line Q1 and the arrangement direction of the Y rows of the island portions 5 is represented by a straight line Q2, the straight lines Q1 and Q2 intersect at an angle α. . The angle α of intersection between the Y-direction side and the Y-row can be arbitrarily adjusted, and is preferably 10 to 30°, for example, when looking at the acute angle side. If the angle of intersection is set in this way, when the optical filter is pasted in line with the frame of the display screen, interference occurs due to interference between the pixel arrangement pattern on the display screen and the arrangement pattern of the plurality of island portions 5 of the optical filter. The occurrence of stripes (moire) can be reduced.

The light transmitting portion 3 of the optical filter 10 is a through hole 51 provided in the light shielding portion 4 . The through hole 51 may be filled with air or may be filled with a light transmissive material. When the through hole 51 is filled with air, the light transmission angle θ can be reduced because the refractive index of transmitted light is small. When the through-hole 51 is filled with the light-transmitting material, the shape of the through-hole 51 is easily retained by the light-transmitting material, and the shape of the light-transmitting portion 3 can be maintained even when the optical filter 10 is deformed. easier to hold.

Examples of the light transmissive material include transparent resin and glass. From the viewpoint of increasing the flexibility of the optical filter 10, a transparent elastomer is preferable. Specific examples of transparent elastomers include, for example, silicone and polyurethane. One or two or more transparent elastomers may be filled in the through-holes. Silicone rubber is preferable as the transparent elastomer from the viewpoint of excellent transparency and heat resistance.

(Light shielding part)
The light shielding portion 4 of the optical filter 10 is the sea portion 6 of the sea-island structure, which is an opaque portion excluding the island portion 5 .
The length of the light shielding portion 4 in the Z direction is the same as the thickness of the optical filter 10, preferably 30 μm to 5000 μm, more preferably 50 μm to 1000 μm, even more preferably 70 μm to 500 μm. If the length is equal to or greater than the lower limit, it becomes easier to control the light transmission angle θ. If the length is equal to or less than the upper limit, the flexibility of the optical filter 10 becomes higher.

The content of the elastomer with respect to the total mass of the light shielding portion 4 is preferably 50 to 99% by mass, more preferably 60 to 97% by mass, and even more preferably 70 to 95% by mass.
When the content is equal to or higher than the above lower limit, the flexibility of the optical filter 10 is sufficiently increased. When the content is equal to or less than the above upper limit, there is enough room for the light shielding material to be sufficiently contained in the light shielding portion 4 . Of the total mass, the rest after removing the content of the elastomer can be assigned to the light shielding material.

A known elastomer is applied to the elastomer contained in the light shielding part 4, and it may be transparent or opaque. One type of the elastomer may be used, or two or more types may be used.
When the light-transmitting portion 3 contains an elastomer, the light-shielding portion 4 and the light-transmitting portion 3 are included in the light-transmitting portion 3 because the flexibility of the optical filter 10 is sufficiently increased by increasing the adhesiveness and integrating the light-shielding portion 4 and the light-transmitting portion 3 . The elastomer and the elastomer contained in the light shielding portion 4 are preferably the same.
The elastomer contained in the light shielding portion 4 is preferably silicone rubber.

The light shielding part 4 preferably contains a light shielding material in addition to a resin such as an elastomer. At least one of a light-absorbing material and a light-reflecting material is used as the light shielding material. A specific example has been described above and will be omitted here.

<Second embodiment>
An optical filter 30 illustrated in FIG. 6 includes the optical filter 10 of the first embodiment as a main body, and has a first transparent sealing layer 7 and a second transparent sealing layer on both main surfaces 1 and 2 of the main body, respectively. 8 are stacked. Further, the light transmitting portion 3 is filled with a transparent resin.

Each transparent sealing layer of the optical filter 30 covers each major surface of the body and protects the body.
The presence of each transparent sealing layer can prevent foreign matter from entering the through-hole from the outside when the light-transmitting portion 3 is a hollow through-hole.
In addition, if the exposed surface of each transparent sealing layer is smooth, diffused reflection of light on the surface is prevented, and it becomes easy to see through the opposite side of the optical filter 30 through the light transmitting portion 3 .

The constituent material of each transparent sealing layer may be transparent, and examples thereof include glass and transparent synthetic resin. Specific examples include silicone, polyurethane, acrylic resin, epoxy resin, polyester, polycarbonate, cycloolefin, and liquid crystal polymer.
From the viewpoint of enhancing adhesion to the main body, the material forming the transparent sealing layer is preferably an elastomer similar to the elastomer contained in the sea portion 6 forming the main body. Further, when the transparent sealing layer is made of glass, it is possible to impart rigidity to the optical filter 30 and further improve heat resistance.

The first transparent sealing layer 7 and the second transparent sealing layer 8 may be made of the same transparent material, or may be made of different transparent materials.
Each of the first transparent sealing layer 7 and the second transparent sealing layer 8 may have a plurality of layers. In the plurality of layers, each layer may be made of the same transparent material, or may be made of different materials. For example, a laminated structure of a glass layer and a transparent resin layer may form the transparent sealing layer. In the laminate structure, the glass layer may be in contact with the main surface of the sheet, or the transparent resin layer may be in contact with the main surface of the sheet.

The thickness of each transparent sealing layer is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 175 μm or less, and even more preferably 5 μm or more and 150 μm or less. If the thickness of the transparent sealing layer is at least the above lower limit, the main body of the optical filter can be sufficiently protected. If the thickness of each transparent sealing layer is equal to or less than the upper limit, sufficient light transmittance can be ensured, and good optical properties can be obtained.
The thickness of the transparent encapsulating layer is obtained as the average value of the values measured at 10 or more randomly selected locations on the cross section. A well-known microstructure observation means such as a measuring microscope is applied for the measurement.

The optical filters of the first and second embodiments described above include the light transmitting portion 3 and the light shielding portion 4 . Of the light rays incident on the first principal surface 1, the light rays incident on the light transmission portion 3 are transmitted therethrough and emerge from the second principal surface 2, and the light rays incident on the light shielding portion 4 are absorbed by this. or reflected.
By appropriately adjusting the arrangement, pitch P, size R, and aspect ratio of the light transmitting portions 3, it is possible to control the transmission angle θ of light rays and the amount of transmitted light.

<Reversal of Light Transmitting Portion and Light Blocking Portion>
In the optical filter 10, the optical filter 20, and the optical filter 30 described above, the sea portion is the light shielding portion and the island portion is the light transmitting portion. As a modification of these, there is an optical filter in which the sea portion is the light transmission portion and the island portion is the light shielding portion. That is, the same optical filters as the optical filters 10 to 30 can be used except that the light shielding portion and the light transmitting portion are reversed.
In the above variant, it is preferred that at least 70% by weight, preferably 80-100% by weight of the total weight of the sea portion is formed by a transparent elastomer. The sea portion may include materials other than elastomers. The island portion contains the light shielding material described above, and may also contain a known binder. From the viewpoint of enhancing the adhesion between the sea portion and the island portions, it is preferable that the island portions also contain the same type of elastomer as the elastomer forming the sea portion.

In the above modified optical filter, among the light rays incident on the first principal surface, the light rays incident on the island portion are absorbed or reflected by the island portion, and the light rays incident on the sea portion are transmitted through the island portion. and emitted from the second main surface.
By appropriately adjusting the arrangement, pitch, size, and aspect ratio of the light shielding portions of the columnar island portions, it is possible to control the transmission angle of light rays and the amount of transmitted light.

The optical filter according to the present invention is attached to an image display device such as a liquid crystal display device for the purpose of, for example, viewing angle control, brightness improvement, glare prevention, and the like. Also, the optical filter can be attached to, for example, a light-emitting body such as a light-emitting diode or an organic electroluminescence element, or a light-receiving body such as a photosensor.

A first resin layer with a thickness of 15 μm made of silicone rubber containing a light shielding material was formed on the surface of the PET film by a conventional method. Carbon black was used as a light shielding material.
A plurality of metal wires were arranged in parallel at a pitch of 100 μm on the surface of the first resin layer with their longitudinal directions aligned. As the metal wire rod, a cylindrical brass wire having a diameter of 30 μm was used.
Next, the surface of the first resin layer on which the plurality of metal wires are arranged is covered with a second resin layer having a thickness of 15 μm made of silicone rubber containing a light shielding material, and the second resin layer and the first resin layer are integrated. Thus, a wire-containing sheet having a plurality of metal wires fixed between the first resin layer and the second resin layer was obtained.
Subsequently, 200 wire-containing sheets prepared by the above method were laminated so that the metal wires contained in each wire-containing sheet were oriented in the longitudinal direction to obtain a laminate of wire-containing sheets.
Next, the laminate was sliced in a direction transverse to the longitudinal direction of the metal wire contained in the laminate to obtain a slice sheet having a thickness of 300 μm. Circular cut surfaces of the metal wire were exposed on the surface of the sliced sheet at a pitch of 100 μm.
Subsequently, the sliced sheet was immersed in a solution containing nitric acid to dissolve and remove the metal wire. As a result, an optical filter having through holes corresponding to the shape of the metal wire was obtained.
Openings with a diameter of about 30 μm were arranged at a pitch of 100 μm on one principal surface and the other principal surface of the obtained optical filter. It was observed that when light was irradiated in the direction perpendicular to one principal surface, the light that entered through the opening exited from the opening on the other principal surface. Next, it was confirmed that when light was applied to one of the principal surfaces from a direction with an elevation angle of 70°, weaker light emitted from the opening of the other principal surface than when irradiated from the normal direction.
From the above results, it was confirmed that the optical filter can be manufactured by the manufacturing method according to the present invention.

1 first main surface 2 second main surface 3 light transmitting portion 4 light shielding portion 5 island portion 51 through hole 6 sea portion 7 first transparent sealing layer 8 second transparent sealing layer S wire rod 10 optical filter 20 Optical filter 30 Optical filter 100 Base material 110 First resin layer 120 Second resin layer 110a First surface 130 Wire containing sheet 140 Laminate 150 Sliced sheet

Claims (10)

arranging a plurality of wires in one direction at arbitrary intervals on the first surface of the first resin layer;
forming a second resin layer covering the plurality of wires on the first surface of the first resin layer to form a wire-containing sheet;
Obtaining a laminate in which a plurality of the wire-containing sheets are laminated with the wires oriented in the same direction;
Obtaining a sliced sheet by slicing a plurality of wires of the laminate in a transverse direction, and
removing all or part of the plurality of wires penetrating the sliced sheet in the thickness direction to obtain an optical filter having a plurality of through holes penetrating the sliced sheet in the thickness direction;
A method for manufacturing an optical filter. 2. The method of manufacturing an optical filter according to claim 1, wherein removing the wire is dissolving the wire by bringing it into contact with a dissolving liquid. After obtaining the slice sheet,
arranging a masking body on one main surface and part of the other main surface of the sliced sheet;
forming a through-hole region having a plurality of through-holes passing through the sliced sheet in the thickness direction by removing the plurality of wires in a region of the sliced sheet where the masking body is not arranged; , obtaining the optical filter in which a non-penetrating region in which the wire remains is formed by removing the masking body;
The method for manufacturing an optical filter according to claim 1 or 2, comprising: 4. The method according to any one of claims 1 to 3, comprising removing a portion of the sliced sheet in the thickness direction from at least one main surface side of the sliced sheet to form a thin layer portion in the sliced sheet. 3. The method for manufacturing the optical filter according to 1. 4. The optical filter according to any one of claims 1 to 3, comprising removing a part of said optical filter in the thickness direction from at least one main surface side of said optical filter to form a thin layer part in said optical filter. 3. The method for manufacturing the optical filter according to 1. 6. The method for manufacturing an optical filter according to claim 1, wherein said first resin layer and said second resin layer are elastomers. 7. The method for manufacturing an optical filter according to claim 1, wherein the first resin layer and the second resin layer contain a light shielding material. The method for manufacturing an optical filter according to any one of claims 1 to 7, wherein the wire is a metal wire. arranging a plurality of wires in one direction at arbitrary intervals on the first surface of the first resin layer;
forming a second resin layer covering the plurality of wires on the first surface of the first resin layer to form a wire-containing sheet;
Obtaining a laminate in which a plurality of the wire-containing sheets are laminated with the wires oriented in the same direction;
obtaining a block in which a plurality of through holes or a plurality of non-through holes corresponding to the wires are formed in the laminate by removing all or part of the plurality of wires included in the laminate; as well as,
Obtaining an optical filter having a plurality of through-holes penetrating in a thickness direction by slice-cutting the plurality of through-holes or the plurality of non-through-holes of the block body in a direction transverse to the longitudinal direction;
A method for manufacturing an optical filter. One end of the plurality of wires protrudes from one surface of the laminate,
10. The method of manufacturing an optical filter according to claim 9, wherein the block is obtained by gripping the end portion and pulling out the plurality of wires from the laminate.

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