JP2023147945A - Optical sheet and optical component - Google Patents

Abstract

To provide an optical sheet including a half mirror layer that selectively reflects light of a specific wavelength region and lets light of other wavelength regions pass through, the optical sheet having both excellent heat resistance and processability, and an optical component that includes said optical sheet and excels in reliability.SOLUTION: An optical sheet 15 according to the present invention comprises: a first substrate 11 that is composed of a resin material as the main material; a half mirror layer 13 that is provided to one surface side of the first substrate 11, and that includes a laminate in which a high refractive index layer and a low refractive index layer are alternately and repeatedly laminated; and a second substrate 12 that is composed of a resin material as the main material, and that is provided to the side of the half mirror layer 13 that is opposite the first substrate 11. The half mirror layer 13 should satisfy the expression Tg1, Tg2≥105°C, where Tg1 represents the glass transition point of the main material constituting the high refractive index layer and Tg2 represents the glass transition point of the main material constituting the low refractive index layer.SELECTED DRAWING: Figure 3

Description

The present invention relates to an optical sheet and an optical component.

In recent years, lenses for eyewear such as glasses and sunglasses have been used to selectively reflect light in a specific wavelength range and transmit light in other wavelength ranges, with the aim of improving their design. An optical sheet having a half mirror layer on its surface has been proposed.

For a lens having such an optical sheet on its surface, for example, an optical sheet having a flat plate shape in plan view is prepared, a protective film is attached to both sides of the optical sheet, and a predetermined shape such as a circular shape in plan view is prepared. Punch out the optical sheet into the shape. Thereafter, this optical sheet is subjected to a thermal bending process under heating to obtain a curved optical sheet having a curved convex surface and a curved concave surface, which are formed into a curved shape by thermal bending. After the protective film is peeled off from the curved optical sheet, the curved optical sheet is placed in a mold having a curved recess so that the recess of the mold and the convex part of the curved optical sheet come into contact with each other. It is manufactured by forming a resin layer (molded layer) mainly composed of a resin material on the concave surface of this curved optical sheet using an insert injection molding method in the adsorbed state (for example, Patent Document 1 reference).

In the manufacturing method of such a lens, as described above, a curved optical sheet is obtained by passing through a heat bending process of thermally bending an optical sheet, and a molding process of molding a resin layer in the concave portions of the curved optical sheet is also carried out. Through these steps, a lens is obtained, but in each of these steps, the optical sheet is exposed to heat, so the optical sheet is required to have excellent heat resistance.

Further, in the heat bending process, the optical sheet is formed into a curved shape including a curved convex surface and a curved concave surface, and therefore, the optical sheet is also required to have excellent workability.

Therefore, we have developed an optical sheet with a half mirror layer that selectively reflects light in a specific wavelength range and transmits light in other wavelength ranges, which has both excellent heat resistance and processability. The reality is that this is what is needed.

JP2009-294445A

An object of the present invention is to achieve both excellent heat resistance and processability in an optical sheet including a half mirror layer that selectively reflects light in a specific wavelength range and transmits light in other wavelength ranges. An object of the present invention is to provide a highly reliable optical sheet and an optical component equipped with such an optical sheet.

Such objects are achieved by the present invention described in (1) to (10) below.
(1) A first base material mainly composed of a resin material having light transmittance;
a half mirror layer provided on one surface side of the first base material and comprising a laminate in which high refractive index layers and low refractive index layers are alternately and repeatedly laminated;
An optical sheet made of the resin material as a main material and comprising a second base material provided on the opposite side of the first base material of the half mirror layer,
In the half mirror layer, the refractive index of the high refractive index layer is higher than the refractive index of the low refractive index layer,
When the glass transition point of the main material constituting the high refractive index layer is Tg1, and the glass transition point of the main material constituting the low refractive index layer is Tg2, Tg1, Tg2 ≧ 105 ° C. optical sheet.

(2) When the refractive index of the high refractive index layer at a wavelength of 589 nm is N1 and the refractive index of the low refractive index layer at a wavelength of 589 nm is N2, the refractive index difference (N1-N2) is 0.05. The optical sheet according to (1) above, which has a particle diameter of 0.25 or less.

(3) The optical sheet according to (1) or (2) above, wherein the high refractive index layer and the low refractive index layer each have an average thickness of 50 nm or more and 300 nm or less.

(4) In the half mirror layer, the number of repetitions in which the high refractive index layer and the low refractive index layer are alternately stacked is 50 or more and 750 or less. The optical sheet described in any of the above.

(5) The optical sheet according to any one of (1) to (4) above, wherein the half mirror layer has a thickness direction retardation (Rth) of 500 nm or less at a wavelength of 589 nm.

(6) The optical sheet according to any one of (1) to (5) above, wherein the glass transition point Tg1 and the glass transition point Tg2 satisfy the following relationship: 0°C≦|Tg1−Tg2|≦60°C.

(7) The optical sheet according to any one of (1) to (6) above, wherein the lower glass transition point of the glass transition point Tg1 and the glass transition point Tg2 is 110°C or more and 250°C or less.

(8) The optical sheet was made into a curved optical sheet having a curved shape with a radius of curvature of 60 mm at a temperature 10° C. higher than the higher glass transition point of the glass transition point Tg1 and the glass transition point Tg2. When the reflectance of light with a wavelength of 589 nm of the curved optical sheet is R1 [%],
After storing the curved optical sheet in a thermal circulation oven at a temperature of 105° C. for 1000 hours, when the reflectance of the curved optical sheet for light at a wavelength of 589 nm is R2 [%], R2/R1× The optical sheet according to any one of (1) to (7) above, which has a reflectance retention of 80% or more as determined by 100%.

(9) The optical sheet is made into a curved optical sheet having a curved shape with a radius of curvature of 60 mm at a temperature 10° C. higher than the higher glass transition point of the glass transition point Tg1 and the glass transition point Tg2, After being stored in a thermal circulation oven at a temperature of 105° C. for 1000 hours, the number of curved optical sheets that maintain the radius of curvature of 60 ± 5 mm is 48 or more out of 50 curved optical sheets. The optical sheet according to any one of (1) to (8) above.

(10) An optical component comprising the optical sheet according to any one of (1) to (9) above.

According to the present invention, in a half mirror layer including a repeating portion constituted by a laminate in which high refractive index layers and low refractive index layers are alternately and repeatedly stacked, Tg1, Tg2≧105°C are satisfied. Therefore, an optical sheet including this half mirror layer exhibits excellent heat resistance. Moreover, since each of the base materials and the half mirror layer that constitute the optical sheet are each made of a resin material as a main material, the optical sheet can be made to have excellent workability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of sunglasses including a lens having a curved optical sheet according to the present invention. FIG. 2 is a schematic diagram for explaining a method for manufacturing a lens having a curved optical sheet according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view which shows 1st Embodiment of the optical sheet of this invention. FIG. 4 is an enlarged cross-sectional view of a part of the half mirror layer included in the optical sheet located in the region [B] surrounded by the dashed line in FIG. 3. FIG. It is a longitudinal cross-sectional view showing a second embodiment of the optical sheet of the present invention.

Hereinafter, the optical sheet and optical component of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

The optical sheet of the present invention includes a first base material mainly composed of a resin material having light transmittance, and a high refractive index layer and a low refractive index layer provided on one surface side of the first base material. a half mirror layer comprising a laminate formed by alternately and repeatedly laminating the above, and a second base material made of the resin material as a main material and provided on the opposite side of the first base material of the half mirror layer. In the half mirror layer, the refractive index of the high refractive index layer is higher than the refractive index of the low refractive index layer, and the glass transition point of the main material constituting the high refractive index layer is Tg1, When the glass transition point of the main material constituting the low refractive index layer is Tg2, it is satisfied that Tg1, Tg2≧105°C.

As described above, in the present invention, in a half mirror layer having a repeating portion constituted by a laminate in which high refractive index layers and low refractive index layers are alternately and repeatedly stacked, Tg1 and Tg2 ≧105°C. I am satisfied. Therefore, an optical sheet including this half mirror layer exhibits excellent heat resistance. Moreover, since each of the base materials and the half mirror layer that constitute the optical sheet are each made of a resin material as a main material, the optical sheet can be made to have excellent workability.

A curved optical sheet having a curved shape including a curved convex surface and a curved concave surface obtained by thermally bending the optical sheet of the present invention under heating can be used, for example, as a lens for sunglasses, which is a type of eyeglasses. The resin substrate having a curved shape (curved resin substrate) is used to impart half-mirror properties to this lens. Therefore, in the following, first, prior to explaining the optical sheet of the present invention, the sunglasses will be explained.

<Sunglasses>
FIG. 1 is a perspective view showing an embodiment of sunglasses including a lens having a curved optical sheet according to the present invention. In FIG. 1, when the sunglasses are worn on the user's head, the surface of the lenses facing the user's eyes is called the back surface, and the surface on the opposite side is called the front surface.

As shown in FIG. 1, sunglasses 100 include a frame 20 and lenses 30 (lenses for spectacles).

Note that in this specification, the term "lens (lens for spectacles)" includes both those that have a light condensing function and those that do not have a light condensing function.

The frame 20 is attached to the user's head and allows the lens 30 to be placed near the front of the user's eyes.

This frame 20 has a rim part 21, a bridge part 22, a temple part 23, and a nose pad part 24.

The rim part 21 has a ring shape, and one rim part 21 is provided for each of the right eye and the left eye, and a lens 30 is attached to the inside thereof. Thereby, the user can visually recognize external information through the lens 30.

Further, the bridge portion 22 has a rod shape, and when worn on the user's head, is located in front of the upper part of the user's nose and connects the pair of rim portions 21.

The temple portion 23 has a temple shape and is connected to an edge of each rim portion 21 on the opposite side of the position where the bridge portion 22 is connected. The temple portion 23 is hung over the user's ear when worn on the user's head.

The nose pad section 24 is provided at the edge of each rim section 21 corresponding to the user's nose when the sunglasses 100 are worn on the user's head, and comes into contact with the user's nose. It has a shape that corresponds to the contact part of the nose. Thereby, the attached state can be stably maintained.

The constituent materials of each part constituting the frame 20 are not particularly limited, and for example, various metal materials, various resin materials, etc. can be used. Note that the shape of the frame 20 is not limited to that shown in the drawings, as long as it can be mounted on the user's head.

Lenses 30 (optical components of the present invention) are attached to each rim portion 21, respectively. The lens 30 is a member having a light transmitting property and having a plate shape whose overall shape is curved outward, and includes a resin layer 35 (molding layer) and a curved optical sheet 10.

The resin layer 35 has light transmittance and is located on the back side of the lens, and when imparting a light condensing function to the lens 30, this resin layer 35 has a light condensing function.

The constituent material of the resin layer 35 is not particularly limited as long as it is a resin material having light transmittance, but for example, various thermoplastic resins, thermosetting resins, various curable resins such as photocurable resins, etc. One type or a combination of two or more types of these can be used.

Examples of resin materials include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers, polyvinyl chloride, polystyrene, polyamide, polyimide, polycarbonate, poly(4-methylpentene-1), ionomers, acrylic resins, Polyesters such as polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. , polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene oxide, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer) ), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, epoxy resins, phenol resins, urea resins, melamine resins, silicone resins, polyurethanes, etc., or copolymers, blends, polymer alloys, etc. mainly based on these Among these, it is preferable that the resin material is the same or the same as the resin material that mainly constitutes the first base material 11 of the curved optical sheet 10 described below. Thereby, it is possible to improve the adhesion between the resin layer 35 and the curved optical sheet 10. Furthermore, since the refractive index difference between the resin layer 35 and the curved optical sheet 10 (first base material 11) can be set low, light is diffusely reflected between the resin layer 35 and the curved optical sheet 10. Since this can accurately suppress or prevent light from occurring, light can be transmitted between the resin layer 35 and the curved optical sheet 10 with excellent light transmittance. Note that the refractive index difference between the resin layer 35 and the curved optical sheet 10 (first base material 11) is preferably 0.1 or less, more preferably 0.05 or less. Thereby, the effect obtained by setting the refractive index difference to a low value can be more clearly exhibited.

The thickness of the resin layer 35 is not particularly limited, and is preferably, for example, 0.5 mm or more and 5.0 mm or less, and more preferably 1.0 mm or more and 3.0 mm or less. Thereby, the lens 30 can achieve both relatively high strength and weight reduction.

The curved optical sheet 10 is a curved resin substrate that is bonded onto the outer surface of the resin layer 35, that is, the curved convex surface, in a curved shape corresponding to this shape. By providing the sunglasses 100, half-mirror properties are imparted to the sunglasses 100. As a result, the sunglasses 100 function as sunglasses having half mirror properties. This curved optical sheet 10 is made of the optical sheet of the present invention in a curved shape, and its detailed explanation will be given later.

Note that, as described above, the lenses 30 included in the sunglasses 100 may or may not have a light collecting function.

In addition to having the frame 20 as described above, the sunglasses 100 may have a frameless structure from the viewpoint of fashionability, lightness, etc.

Further, in the present embodiment, the glasses including the lenses 30 are applied to the sunglasses 100, but the glasses are not limited to this, and can be used, for example, to prevent prescription glasses, fancy glasses, wind and rain, dust, chemicals, etc. It may also be goggles or the like to protect the eyes.

In the sunglasses 100 (glasses) having the above configuration, the lenses 30 included in the sunglasses 100 are manufactured by, for example, a method for manufacturing the lenses 30 as shown below.

<Lens manufacturing method>
FIG. 2 is a schematic diagram for explaining a method of manufacturing a lens having a curved optical sheet according to the present invention. Note that, hereinafter, for convenience of explanation, the upper side of FIG. 2 will be referred to as "upper" and the lower side will be referred to as "lower".

Hereinafter, each step of the method for manufacturing a lens 30 including a curved optical sheet 10 in which the optical sheet 15 of the present invention is curved will be described in detail.
[1] First, an optical sheet 15 (optical sheet of the present invention) comprising a first base material 11, a half mirror layer 13, and a second base material 12, which are laminated in this order and has a flat overall shape. ). Then, by pasting protective films 50 (masking tape) on both sides of this optical sheet 15, a multilayer laminate 150 in which protective films 50 are pasted on both sides of the optical sheet 15 is obtained (see FIG. 2(a)). .

[2] Next, as shown in FIG. 2(b), the prepared multilayer laminate 150, that is, the optical sheet 15 with the protective film 50 attached to both sides of the optical sheet 15, is heated in the thickness direction. By punching, the multilayer laminate 150 has a circular shape in plan view.

[3] Next, as shown in FIG. 2(c), the circular multilayer laminate 150 is subjected to thermal bending under heating, thereby forming the multilayer laminate 150 into a first base material. The curved multilayer laminate 200 has a curved shape in which the 11 side is a curved concave surface and the second base material 12 side is a curved convex surface. Thereby, the flat optical sheet 15 can be made into the curved optical sheet 10 having a curved shape with the protective film 50 attached to both sides.

This heat bending process is usually performed by press molding or vacuum forming.
At this time, the heating temperature (molding temperature) of the multilayer laminate 150 (optical sheet 15) is as described above. In consideration of the softening temperature, it is preferably set to about 120°C or more and 250°C or less, more preferably about 130°C or more and 180°C or less. By setting the heating temperature within this range, the optical sheet 15 is softened or melted while preventing deterioration or deterioration of the optical sheet 15, and the optical sheet 15 is reliably thermally bent to form a curved shape. It can be an optical sheet 10.

[4] Next, the protective film 50 is peeled off from the curved optical sheet 10 that has been thermally bent. Thereafter, as shown in FIG. 2(d), the curved concave surface of the mold 40 and the curved convex surface of the curved optical sheet 10 are brought into contact with a mold 40 having a curved concave surface. With the sheet 10 adsorbed, a resin layer 35 mainly made of a resin material is injection molded onto the curved concave surface of the curved optical sheet 10 using, for example, an insert injection molding method. That is, by cooling and solidifying the molten material of the resin layer 35 in contact with the curved concave surface of the curved optical sheet 10, an adhesive layer or the like is formed on the curved concave surface of the curved optical sheet 10. The resin layer 35 is molded in direct contact with the resin layer 35 without intervening. As a result, a lens 30 (optical component of the present invention) including the thermally bent curved optical sheet 10 and the resin layer 35 is manufactured.

When injection molding this resin layer 35, the heating temperature (molding temperature) of the constituent material of the resin layer 35 to bring it into a molten state is set as appropriate depending on the type of constituent material of the resin layer 35. When the constituent material of the layer 35 is the same kind or the same as the constituent material of the first base material 11 included in the curved optical sheet 10 described below, the temperature is preferably 180°C or more and 320°C or less, more preferably 230°C or more and 300°C or less. It is set to a certain degree. By setting the heating temperature within this range, the constituent material of the resin layer 35 in a molten state can be reliably supplied to the curved concave surface of the curved optical sheet 10.

Moreover, among the insert injection molding methods, the injection compression molding method is preferably used. In the injection compression molding method, a resin material for forming the resin layer 35 is injected into the mold 40 at low pressure, and then the mold 40 is closed at high pressure to apply compressive force to the resin material. This is preferably used because optical anisotropy due to molding distortion or local orientation of resin molecules during molding is less likely to occur in the resin layer 35 as a molded body, and thus in the lens 30. Further, by controlling the mold compression force uniformly applied to the resin material, the resin material can be cooled at a constant specific volume, so it is possible to obtain the resin layer 35 with high dimensional accuracy.

The optical sheet 15 of the present invention having a curved shape is used as the curved optical sheet 10 included in the lens 30 manufactured by the lens manufacturing method described above. Hereinafter, each embodiment of this optical sheet 15 will be described in detail.
<<First embodiment>>
FIG. 3 is a longitudinal cross-sectional view showing the first embodiment of the optical sheet of the present invention, and FIG. 4 shows a half mirror layer included in the optical sheet located in the region [B] surrounded by the dashed line in FIG. FIG. 3 is an enlarged cross-sectional view of a portion thereof.

Note that, hereinafter, for convenience of explanation, the upper side of FIG. 3 will be referred to as "upper" and the lower side will be referred to as "lower". In addition, the x direction in Figures 3 and 4 is referred to as the "left-right direction" or "flow direction (MD)," the y direction is referred to as the "back-and-forth direction" or "vertical direction (TD)," and the z direction is referred to as the "up-down direction." . Further, in FIGS. 3 and 4, the thickness direction of the optical sheet is exaggerated, so the dimensions differ greatly from the actual dimensions.

In this embodiment, as shown in FIG. 3, the optical sheet 15 (optical substrate) includes a first base material 11 having light transmittance, and a light transmittance base material 11 provided on one side of the first base material 11. a second base material 12 having a half mirror layer 13 provided between the first base material 11 and the second base material 12; A first adhesive layer 14 is provided between the half mirror layer 13 and the first base material 11, and a first adhesive layer 14 is provided between the half mirror layer 13 and the second base material 12 (the other base material). , a second adhesive layer 16 that joins the half mirror layer 13 and the second base material 12.

In the optical sheet 15, by setting the positional relationship in which each layer is arranged as described above, the half mirror layer 13 is located between the first base material 11 and the second base material 12, so that the optical sheet 15 is not exposed on the surface. That is, it does not constitute the outermost layer exposed on the top or bottom surface of the optical sheet 15. Therefore, as in the case where the outermost layer is configured, the half mirror layer 13 is reliably prevented from being hit by dust, flying stones, even rain, etc., and from being abraded by other members, etc. be able to. Therefore, it is possible to reliably prevent the half mirror layer 13 from being damaged due to this collision or friction. Therefore, the optical sheet 15 can maintain its design and optical properties over a long period of time.

Furthermore, in the optical sheet 15 having such a configuration, the half mirror layer 13 is composed of a laminate in which high refractive index layers 31 and low refractive index layers 32 are alternately and repeatedly laminated. As a result, the half mirror layer 13 selectively reflects light in a specific wavelength range among the incident light and transmits the remaining part, so that when a person is located on the back side of the optical sheet 15, When a person wears the sunglasses 100, the person can visually recognize the front side of the optical sheet 15 through the optical sheet 15. Further, since the reflected light in a specific wavelength range is visible on the front side of the optical sheet 15, the optical sheet 15 can be made to have a good design.

Each layer constituting this optical sheet 15 will be explained below.
The first base material 11 is an optical sheet 15 that supports a half mirror layer 13 (laminate) and arranges the half mirror layer 13 between the first base material 11 and a second base material 12 described later. It constitutes the outermost layer and has a function as a protective layer that protects the half mirror layer 13.

In the optical sheet 15, the first base material 11 and the second base material 12, which will be described later, constitute the outermost layer of the optical sheet 15, so that the half mirror layer 13 is not exposed on the surface of the optical sheet 15. . Therefore, when this optical sheet 15 is applied to what the lens 30 has, the half mirror layer 13 constitutes the outermost layer, and as in the case where this half mirror layer 13 is exposed, the half mirror layer 13 is covered with sand. It is possible to reliably prevent dust, rain, etc. from colliding with the half mirror layer 13 and abrasion of the half mirror layer 13 by other members. Therefore, it is possible to reliably prevent the half mirror layer 13 from being damaged due to this collision or friction. Therefore, the design and optical properties of the optical sheet 15 can be maintained over a long period of time.
This first base material 11 may be stretched or unstretched.

This first base material 11 is not particularly limited as long as it is mainly composed of a transparent resin material, but it may contain a thermoplastic transparent resin (base resin) as its main material. It is preferable.

Examples of the transparent resin include, but are not limited to, acrylic resins, polystyrene resins, polyethylene resins, polypropylene resins, polyester resins such as polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), and polycarbonate resins. , polyamide resins, cycloolefin resins, vinyl chloride resins, polyacetal resins, and other transparent resins, and one type or a combination of two or more of these can be used. Among these, polycarbonate resins or polyamide resins are preferred, and polycarbonate resins are particularly preferred. Polycarbonate resin has high mechanical strength such as transparency (translucency) and rigidity, and also has high heat resistance. Therefore, by using polycarbonate resin as the transparent resin, the transparency and 1 The impact resistance and heat resistance of the base material 11 can be improved.

Although various resins can be used as the polycarbonate resin, aromatic polycarbonate resins are particularly preferred. The aromatic polycarbonate resin has an aromatic ring in its main chain, and as a result, the first base material 11 having superior strength can be obtained.

This aromatic polycarbonate resin is synthesized, for example, by interfacial polycondensation reaction between bisphenol and phosgene, transesterification reaction between bisphenol and diphenyl carbonate, and the like.

Examples of bisphenol include bisphenol A and bisphenol (modified bisphenol) which is the origin of the repeating unit of polycarbonate shown in the following formula (1A).

(In formula (1A), X is an alkyl group having 1 to 18 carbon atoms, an aromatic group, or a cycloaliphatic group, and Ra and Rb are each independently an alkyl group having 1 to 12 carbon atoms. , m and n are each integers from 0 to 4, and p is the number of repeating units.)

In addition, specific examples of the bisphenol that is the origin of the repeating unit of the polycarbonate shown in the formula (1A) include 4,4'-(pentane-2,2-diyl)diphenol, 4,4'-( Pentane-3,3-diyl)diphenol, 4,4'-(butane-2,2-diyl)diphenol, 1,1'-(cyclohexanediyl)diphenol, 2-cyclohexyl-1,4-bis( 4-hydroxyphenyl)benzene, 2,3-biscyclohexyl-1,4-bis(4-hydroxyphenyl)benzene, 1,1'-bis(4-hydroxy-3-methylphenyl)cyclohexane, 2,2'- Examples include bis(4-hydroxy-3-methylphenyl)propane, and one or more of these may be used in combination.

In particular, as the polycarbonate resin, it is preferable to use a bisphenol type polycarbonate resin having a skeleton derived from bisphenol as a main component. By using such a bisphenol type polycarbonate resin, the first base material 11 exhibits even better strength.

Further, the first base material 11 may be colorless, or may be of any color such as red, blue, yellow, etc., as long as it has light transmittance.

These colors can be selected by including dyes or pigments in the first base material 11. Examples of the dye include acid dyes, direct dyes, reactive dyes, and basic dyes, and one type or a combination of two or more types selected from these can be used.

Specific examples of dyes include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C. I. Acid Red 52, 80, 82, 249, 254, 289, C. I. Acid Blue 9,45,249, C. I. Acid Black 1, 2, 24, 94, C. I. Food black 1, 2, C. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C. I. Direct black 19, 38, 51, 71, 154, 168, 171, 195, C. I. Reactive Red 14, 32, 55, 79, 249, C. I. Examples include Reactive Black 3, 4, and 35.

The first base material 11 may optionally contain, in addition to the above-mentioned transparent resin, dye, or pigment, an antioxidant, a filler, a plasticizer, a light stabilizer, an ultraviolet absorber, a heat ray absorber, and a flame retardant. It may contain various additives such as.

Further, the refractive index of the first base material 11 at a wavelength of 589 nm is preferably 1.3 or more and 1.8 or less, and more preferably 1.4 or more and 1.65 or less. By setting the refractive index of the first base material 11 within the above numerical range, it is possible to accurately suppress or prevent interference with the function of the half mirror layer 13 that transmits part of the incident light and reflects the remaining part. be able to.

The average thickness of the first base material 11 is preferably set to 0.1 mm or more and 1.5 mm or less, more preferably 0.2 mm or more and 0.8 mm or less. By setting the average thickness of the first base material 11 within this range, it is possible to reduce the thickness of the optical sheet 15 while accurately suppressing or preventing the optical sheet 15 from being bent. Therefore, the color of the light in the specific wavelength range that is selectively reflected by the half mirror layer 13 can be more uniformly viewed over the entire optical sheet 15.

The second base material 12 is the outermost layer of the optical sheet 15 that supports the half mirror layer 13 (optical multilayer film) and arranges the half mirror layer 13 between the first base material 11 and the second base material 12. It has a function as a protective layer that protects the half mirror layer 13.

In the optical sheet 15, the second base material 12 constitutes the outermost layer of the optical sheet 15, so that the half mirror layer 13 is not exposed on the surface of the optical sheet 15. Therefore, when this optical sheet 15 is applied to what the lens 30 has, the half mirror layer 13 constitutes the outermost layer, and as in the case where this half mirror layer 13 is exposed, the half mirror layer 13 is covered with sand. It is possible to reliably prevent dust, rain, etc. from colliding with the half mirror layer 13 and abrasion of the half mirror layer 13 by other members. Therefore, it is possible to reliably prevent the half mirror layer 13 from being damaged due to this collision or friction. Therefore, the design and optical properties of the optical sheet 15 can be maintained over a long period of time.

Like the first base material 11, the second base material 12 may be stretched or unstretched.

Furthermore, the second base material 12 can be made of the same materials as those mentioned for the first base material 11. Note that the constituent material of the second base material 12 and the constituent material of the first base material 11 may be the same (same kind) or may be different.

Further, the refractive index of the second base material 12 at a wavelength of 589 nm may be the same or different from the refractive index of the first base material 11, but is 1.3 or more and 1.8 or less. It is preferably 1.4 or more and 1.65 or less. By setting the refractive index of the second base material 12 within the above numerical range, it is possible to accurately suppress or prevent interference with the function as the half mirror layer 13 that transmits a part of the incident light and reflects the remaining part. be able to.

Further, the average thickness of the second base material 12 may be the same or different from that of the first base material 11, but for example, the average thickness is 0.2 mm or more and 1.5 mm or less. It is preferably 0.2 mm or more and 0.8 mm or less. By setting the average thickness of the second base material 12 within this range, it is possible to reduce the thickness of the optical sheet 15 while accurately suppressing or preventing the optical sheet 15 from being bent. Therefore, the color of the light in the specific wavelength range that is selectively reflected by the half mirror layer 13 can be more uniformly viewed over the entire optical sheet 15.

Further, the first base material 11 and the second base material 12 described above have a glass transition point of 105° C. or higher, similar to the high refractive index layer 31 and the low refractive index layer 32 included in the half mirror layer 13 described later. It is preferable that Thereby, it is possible to further improve the heat resistance and heat bendability of the first base material 11 and the second base material 12, and ultimately of the optical sheet 15.

The half mirror layer 13 is an intermediate layer located at the center in the thickness direction of the optical sheet 15, and in the present invention, it selectively reflects light having a specific wavelength range (specific wavelength range), and this reflection The remaining light that is not transmitted is transmitted.

As shown in FIG. 4, the half mirror layer 13 is formed by alternately and repeatedly stacking a high refractive index layer 31 having a high refractive index and a low refractive index layer 32 having a low refractive index for light in the visible light region. It is provided with a repeating portion 33 made of a laminate. That is, the half-mirror layer 13 is constructed of a multilayer laminate in which the repeating portion 33 is repeatedly stacked a plurality of times, thereby repeating a structure in which one high refractive index layer 31 is sandwiched between two low refractive index layers 32. It is something that you have.

In this half mirror layer 13, the high refractive index layer 31 contains a resin material that has a high refractive index for light in the visible light region, and the low refractive index layer 32 contains a resin material that has a high refractive index for light in the visible light region. By having a structure containing a low resin material, between the high refractive index layer 31 and the low refractive index layer 32, the refractive index difference for light in the visible light region is increased and the refractive index difference for unreflected light is decreased. be able to. This allows the half mirror layer 13 to function as a multilayer laminate, that is, a multilayer laminate reflector that selectively reflects light in a specific wavelength region of the visible light region and transmits the remaining light that is not reflected as transmitted light. can be granted. In other words, when light in the visible light region enters the half mirror layer 13 as incident light, the half mirror layer 13 blocks (reflects) the reflected light (reflected light) of the incident light to the maximum extent possible. On the other hand, when light that is not reflected (transmitted light) enters the half mirror layer 13 as incident light, the multilayer laminated reflecting plate blocks the transmitted light with a minimum amount, that is, transmits it with a maximum amount. Demonstrate function.

Here, in order to selectively reflect light in a specific wavelength region of the visible light region and transmit the remaining light that is not reflected as transmitted light, specifically, in the half mirror layer 13, the high refractive index layer 31 When the refractive index at a wavelength of 589 nm is N1, and the refractive index at a wavelength of 589 nm of the low refractive index layer 32 is N2, the refractive index difference (N1-N2) is preferably set to 0.05 or more and 0.25 or less. has been done. By setting the refractive index difference (N1-N2) at a wavelength of 589 nm within the above range, the refractive index difference for light in the visible light region is set to be large between the high refractive index layer 31 and the low refractive index layer 32. It can be said that the light in the visible light range can be blocked (reflected) to the maximum extent possible.

Note that a specific wavelength region of visible light that blocks (reflects) light in the visible light region to the maximum extent and blocks unreflected light to the minimum, and furthermore, the intensity of the light in that wavelength region is determined by the high refractive index layer 31. and the type of resin material contained in each of the low refractive index layers 32, the number of repetitions of the high refractive index layer 31 and the low refractive index layer 32 in the half mirror layer 13 (repetitive portion 33), and the The desired size (within a range) can be adjusted by appropriately setting the thicknesses of the index layer 31 and the low refractive index layer 32).

Therefore, by providing the lens 30 with the curved optical sheet 10 in which the optical sheet 15 has a curved shape, it is possible to prevent external light irradiated from the outside of the sunglasses 100, that is, direct sunlight and its reflected light. When transmitted through the optical sheet 15, light in a specific wavelength region in the visible light region is reflected by the optical sheet 15, and the remaining light, that is, attenuated light that is not reflected, reaches the eyes of the wearer of the sunglasses 100. It will be reached. This prevents light in a specific wavelength range from entering the eyes of visible light included in direct sunlight and reflected light, thereby improving the wearer's ability to recognize objects. can. On the other hand, light in a specific wavelength range (reflected light) reflected from the optical sheet 15 is visible to a person located on the opposite side of the wearer through the lens 30 (optical sheet 15). , the design of the sunglasses 100 can be improved. In this manner, the optical sheet 15 functions as a reflector that selectively reflects light having a specific wavelength range among visible light and selectively transmits the remainder.

Further, in the above-described lens manufacturing method, the optical sheet 15 is subjected to heat bending in the step [3] and injection molding in the step [4], so it undergoes a thermal history. In addition, as mentioned above, the heating temperature during these processes is preferably set to about 120° C. or more and 250° C. or less in the step [3], and preferably about 180° C. or more and 320° C. or less in the step [4]. Therefore, the half mirror layer 13 included in the optical sheet 15 is required to have excellent heat resistance.

As described above, the half mirror layer 13 exhibits the characteristic of reflecting light in a specific wavelength region in the visible light region to the maximum extent, and transmitting the remaining light that is not reflected to the maximum extent. Therefore, it can be said that the half mirror layer 13 exhibiting excellent heat resistance means that the characteristics of the half mirror layer 13 are suitably maintained even when exposed to severe conditions.

Therefore, in the present invention, the main material of the high refractive index layer 31 and the main material of the low refractive index layer 32, which constitute the half mirror layer 13, have a high refractive index with respect to light in the visible light region. , when the glass transition point of the resin material included in the high refractive index layer 31 is Tg1, and the glass transition point of the resin material included in the low refractive index layer 32, which has a low refractive index for light in the visible light region, is Tg2. , Tg1, Tg2≧105°C. In this way, by selecting a layer in which both Tg1 and Tg2 are 105° C. or higher, both the high refractive index layer 31 and the low refractive index layer 32 can be made to have excellent heat resistance. Therefore, it is possible to accurately suppress or prevent a change in the film thickness of the refractive index layer having a lower glass transition point among the low refractive index layer 32 and the high refractive index layer 31. Therefore, the half mirror layer 13 included in the optical sheet 15 is excellent because it accurately suppresses or prevents deterioration in its function as a reflector that selectively reflects light in a specific wavelength range (visible light). Demonstrates excellent heat resistance. Note that the resin material with a low refractive index in the low refractive index layer 32 is generally selected to have a lower glass transition point than the resin material with a high refractive index included as the main material of the high refractive index layer 31. The tendency is high. Therefore, by using a resin material with a low refractive index whose glass transition point Tg2 is 105° C. or higher, the above effect can be reliably exhibited.

The optical sheet 15 including this half mirror layer 13 has a glass transition point Tg1 of the main material constituting the high refractive index layer 31 and a glass transition point Tg2 of the main material constituting the low refractive index layer 32, whichever is higher. Light with a wavelength of 589 nm from the curved optical sheet 10 when the optical sheet 15 is made into a curved shape with a radius of curvature of 60 mm by pressing it against a metal mold at a temperature 10° C. higher than the glass transition point. Let the reflectance of the curved optical sheet 10 be R1 [%], and after storing this curved optical sheet 10 in a thermal circulation oven at a temperature of 105°C for 1000 hours, the reflectance of the curved optical sheet 10 for light with a wavelength of 589 nm is R2 When expressed as [%], the reflectance retention determined by R2/R1 x 100 [%] is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more. preferable.

As mentioned above, even if the curved optical sheet 10 having a curved shape with a radius of curvature of 60 mm is exposed to the severe condition of being stored for 1000 hours in a temperature environment of 105° C., the reflectance retention will not exceed the lower limit. Maintains a value greater than or equal to the value. As described above, since the reflectance retention is maintained at a ratio equal to or higher than the lower limit value, it can be said that this half mirror layer 13 exhibits excellent heat resistance. Further, the reflectance R1 of the curved optical sheet 10 for light having a wavelength of 589 nm is preferably 40% or more, and more preferably 45% or more and 70% or less. It can be said that such a curved optical sheet 10 reflects light in the visible light region with excellent reflectance.

Further, in the above-described lens manufacturing method, the optical sheet 15 is subjected to heat bending in the step [3], so that the first base material 11 side (upper side) has a curved concave surface, and the second base material 12 has a curved concave surface. The optical sheet 10 is thermally bent into a curved optical sheet 10 having a curved convex side (lower side). Therefore, the half mirror layer 13 included in the optical sheet 15 is required to have excellent workability.

As described above, in the present invention, the half mirror layer 13 is made of a material having a glass transition point of Tg1 as the main material of the high refractive index layer 31 and the main material of the low refractive index layer 32, which constitute the half mirror layer 13. It contains a resin material and a resin material whose glass transition point is Tg2.

In this way, by configuring the main materials of the high refractive index layer 31 and the low refractive index layer 32 that constitute the half mirror layer 13 from resin materials, both the high refractive index layer 31 and the low refractive index layer 32 can be formed. can be made to have excellent workability. Therefore, when thermally bending the optical sheet 15 into a curved shape, for example, when the high refractive index layer 31 and the low refractive index layer 32 are made of metal-based (inorganic) material, Cracks can be accurately suppressed or prevented from occurring in the high refractive index layer 31 and the low refractive index layer 32.

This optical sheet 15 has a glass transition point 10 higher than the glass transition point Tg1 of the main material constituting the high refractive index layer 31 and the glass transition point Tg2 of the main material constituting the low refractive index layer 32. The optical sheet 15 is pressed against a metal mold at a high temperature of 60 mm to form a curved optical sheet 10 having a radius of curvature of 60 mm, and this curved optical sheet 10 is placed in a thermal circulation oven at a temperature of 105 °C. It is preferable that the number of curved optical sheets 10 that maintain a shape with a radius of curvature of 60 ± 5 mm after being stored in an environment for 1000 hours is 48 or more out of 50 curved optical sheets 10, More preferably, the number is 50.

As mentioned above, even if the curved optical sheet 10, which has a curved shape with a radius of curvature of 60 mm, is exposed to the harsh conditions of being stored in a temperature environment of 105° C. for 1000 hours, the shape of the curved optical sheet 10 is maintained. The property is maintained to be equal to or higher than the lower limit value. As described above, since the shape retention is maintained at a rate equal to or higher than the lower limit value, it can be said that this optical sheet 15 exhibits excellent workability.

As mentioned above, the repeating part 33 (laminate) blocks (reflects) light in the visible light region to the maximum extent and blocks unreflected light to the minimum, and furthermore, The intensity of the light depends on the type of resin material contained in the high refractive index layer 31 and the low refractive index layer 32, and the repetition of the high refractive index layer 31 and the low refractive index layer 32 in the half mirror layer 13 (repetitive part 33). The desired size (within a range) can be adjusted by appropriately setting the number and the thickness of the half mirror layer 13 (high refractive index layer 31, low refractive index layer 32).

Specifically, in the present invention, in such a half mirror layer 13 (repetitive part 33), sodium D line (589 nm), which is generally used as a reference wavelength of visible light, is used as a representative value, and By defining the magnitude of the refractive index difference (N1-N2) between the refractive index N1 of the high refractive index layer 31 and the refractive index N2 of the low refractive index layer 32 to preferably 0.05 or more and 0.25 or less, The half mirror layer 13 (repetitive portion 33), that is, the reflective polarizing plate may be configured to reflect maximum light in the visible light region, specifically, visible light in the wavelength range of 400 nm to 780 nm.

Furthermore, in the present invention, as the main material of the high refractive index layer 31 and the main material of the low refractive index layer 32, a glass transition of a resin material having a high refractive index for light in the visible light region included in the high refractive index layer 31 is used. Select a material that satisfies the relationship between the point Tg1 and the glass transition point Tg2 of the resin material included in the low refractive index layer 32 and having a low refractive index for light in the visible light region: Tg1, Tg2≧105°C. As a result, the half mirror layer 13 (repetitive portion 33), that is, the reflective plate (multilayer laminated reflective plate) can exhibit excellent heat resistance.

As mentioned above, the main material of the high refractive index layer 31 satisfies that the refractive index difference (N1-N2) is preferably 0.05 or more and 0.25 or less, and Tg1, Tg2≧105°C. That is, the resin material having a high refractive index for light in the visible light region and the main material of the low refractive index layer 32, that is, the resin material having a low refractive index for light in the visible light region, are each amorphous. It is preferable that at least one of polycarbonate resin, polystyrene resin, polyether resin, styrene resin, polyester resin, and acrylic resin is used. More preferably, it is at least one of them. By appropriately selecting the main materials of the high refractive index layer 31 and the low refractive index layer 32 from these materials, the half mirror layer 13 including the high refractive index layer 31 and the low refractive index layer 32 can be formed relatively easily. It is possible to satisfy both that the rate difference (N1-N2) is preferably 0.05 or more and 0.25 or less, and that Tg1, Tg2≧105°C.

Considering the above points, the main materials for the high refractive index layer 31 include polyester resins such as polycarbonate (PC), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), polyether sulfone ( At least one of PES) and polyarylate (PAR) is preferably selected.

The main materials of the low refractive index layer 32 include polyester resins such as polycarbonate (PC), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), and acrylic resins such as polymethyl methacrylate (PMMA). , polystyrene (PS), styrenic resin such as acrylonitrile-styrene copolymer (AS), and polyarylate (PAR).

When using such a resin material, the combination of main materials contained in the high refractive index layer 31 and the low refractive index layer 32 is specifically polycarbonate (PC) and polymethyl methacrylate (PMMA). combination, combination of polyarylate (PAR) and polymethyl methacrylate (PMMA), combination of polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA), combination of polyethersulfone (PES) and polyarylate (PAR). ), a combination of polyethylene naphthalate (PEN) and acrylonitrile-styrene copolymer (AS), a combination of polyethylene naphthalate (PEN) and polymethyl methacrylate (PMMA), etc. According to such a combination, the refractive index difference (N1-N2) is preferably 0.05 or more and 0.25 or less, and Tg1, Tg2≧105°C are both satisfied. It can be done.

Note that the high refractive index layer 31 and the low refractive index layer 32 may each contain an additive such as a filler in addition to the main material. Thereby, the half mirror layer 13 including the high refractive index layer 31 and the low refractive index layer 32 has a refractive index difference (N1-N2) of preferably 0.05 or more and 0.25 or less, and Tg1, Tg2≧ Both the temperature and temperature of 105° C. can be more reliably satisfied.

Examples of fillers include, but are not limited to, inorganic fillers such as silica, alumina, calcium carbonate, strontium carbonate, calcium phosphate, kaolin, talc, and smectite, crosslinked polystyrene, and styrene-divinylbenzene copolymers. Among them, organic fillers such as strontium carbonate and smectite are preferred, and at least one of strontium carbonate and smectite is preferred. It is more preferable that there be.

Further, the filler may have any shape such as spherical or flat particulate, granule, pellet, or scale, but it is preferably contained in particulate form.

In the high refractive index layer 31 and the low refractive index layer 32 obtained by the combination of resin materials as described above, the glass transition point Tg1 of the resin material having a high refractive index for light in the visible light region and the light in the visible light region The glass transition point Tg2 of a resin material having a low refractive index relative to the glass transition point Tg2 should satisfy the relationship that Tg1, Tg2 ≧ 105 ° C. In other words, the lower temperature of Tg1 and Tg2 should satisfy the relationship that the lower temperature is 105 ° C. or more, It is preferable that the lower temperature of Tg1 and Tg2 satisfy the relationship of 110° C. or more and 250° C. or less, and it is more preferable that the lower temperature of Tg1 and Tg2 satisfy the relationship of 110° C. or more and 200° C. or less. Furthermore, it is preferable to satisfy the relationship 0°C≦|Tg1−Tg2|≦60°C, and more preferably to satisfy the relationship 25°C≦|Tg1−Tg2|≦60°C. In this way, both Tg1 and Tg2 are within the above range, and by selecting a layer in which the difference between the two is equal to or less than the upper limit value, both the high refractive index layer 31 and the low refractive index layer 32 can be Since the half mirror layer 13 can be made to have excellent heat resistance, the half mirror layer 13 can be made to reliably exhibit excellent heat resistance.

Furthermore, the refractive index difference (N1-N2), which is a relational expression between the refractive index N1 of the high refractive index layer 31 at a wavelength of 589 nm and the refractive index N2 of the low refractive index layer 32 at a wavelength of 589 nm, is 0.05 or more. It is preferably 0.25 or less, and more preferably 0.08 or more and 0.25 or less. Further, the high refractive index layer 31 preferably has a refractive index N1 of 1.57 or more and 1.85 or less at a wavelength of 589 nm, and the low refractive index layer 32 preferably has a refractive index N2 of 1.49 or more at a wavelength of 589 nm. It is preferable that it is 1.67 or less. Thereby, light in the visible light region can be reflected more reliably.

Furthermore, the average thickness of the high refractive index layer 31 and the low refractive index layer 32 is preferably 50 nm or more and 300 nm or less, and more preferably 50 nm or more and 200 nm or less. In the average thickness within this range, the optical thickness (average thickness of the layer x refractive index of the layer) of the high refractive index layer 31 and the low refractive index layer 32 is determined by the wavelength of light in the visible light region to be selectively reflected. Set the size to 1/4 of the original size. This makes it possible to mutually intensify the light reflected at the interface, so that the half mirror layer 13 can selectively reflect light in the visible light region.

Further, in the repeating portion 33 in which the high refractive index layer 31 and the low refractive index layer 32 are laminated, the number of laminations is preferably 50 or more and 750 or less, and 100 or more and 600 or less. is more preferable.

Visible The wavelength of light (wavelength region) that is blocked to the maximum in the optical region can be adjusted to a desired size (within a range).

Further, the half mirror layer 13 may be either stretched or unstretched, but is preferably unstretched. Specifically, the half mirror layer 13 is calculated using the following calculation formula (A ) The thickness direction retardation (Rth) at a wavelength of 589 nm is preferably 500 nm or less, more preferably 300 nm or less.

Rth=[(nx+ny)/2-nz]・d... (A)
(In the above calculation formula (A), nx, ny are the in-plane principal refractive indices of the half mirror layer 13, nz is the refractive index of the half mirror layer 13 in the thickness direction, and d is the thickness of the half mirror layer 13. )

Here, by making the half mirror layer 13 stretched, the apparent glass transition point of the half mirror layer 13 can be improved, that is, the half mirror layer 13 can be made to have excellent heat resistance. However, on the other hand, there is a problem in that heat bendability (workability) decreases. On the other hand, in the present invention, as mentioned above, resin materials included in the high refractive index layer and the low refractive index layer are selected that satisfy Tg1, Tg2≧105°C. Excellent heat resistance is imparted to the mirror layer 13. By preferably selecting a non-stretched half mirror layer 13, it is possible to further improve the heat bendability of the half mirror layer 13 and, by extension, the optical sheet 15.

The first adhesive layer 14 is provided between the first base material 11 (one base material) and the half mirror layer 13 and has a function of bonding the first base material 11 and the half mirror layer 13 together. Thereby, excellent adhesion can be provided between the first base material 11 and the half mirror layer 13 via the first adhesive layer 14.

Further, the second adhesive layer 16 is provided between the second base material 12 (the other base material) and the half mirror layer 13, and has a function of joining the second base material 12 and the half mirror layer 13. have Thereby, excellent adhesion can be provided between the second base material 12 and the half mirror layer 13 via the second adhesive layer 16.

The first adhesive layer 14 and the second adhesive layer 16 are each made of a light-transmitting adhesive. Examples of this adhesive include, but are not limited to, silicone-based, silylated urethane resin-based, urethane resin-based, epoxy-based, polyolefin-based, chlorinated polyolefin-based, acrylic-based, cyanoacrylate-based, rubber-based, polyester-based, Examples include polyimide adhesives, phenolic adhesives, and the like.

Among these, it is preferable that the first adhesive layer 14 and the second adhesive layer 16 are made of a urethane resin adhesive. Thereby, when heat bending the optical sheet 15 to the curved optical sheet 10 having a curved shape, it is possible to impart heat resistance necessary for the heat bending process. Furthermore, it is also preferable that the adhesive is made of silicone adhesive. Thereby, gas generation during curing of the adhesive can be accurately suppressed or prevented. Therefore, it is possible to accurately suppress or prevent air bubbles from remaining in the adhesive layers 14 and 16.

Note that the first adhesive layer 14 and the second adhesive layer 16 may be the same or the same type, or may be different from the same or the same type.

Further, the refractive index of the first adhesive layer 14 and the second adhesive layer 16 at a wavelength of 589 nm is preferably 1.3 or more and 1.7 or less, and 1.4 or more and 1.65. The following is more preferable.

The thickness of the first adhesive layer 14 and the second adhesive layer 16 is preferably, for example, 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 35 μm or less, each independently. Such first adhesive layer 14 and second adhesive layer 16 can reliably bond the first adhesive layer 14 and second adhesive layer 16 to the half mirror layer 13, respectively.

Further, the total thickness of the optical sheet 15 is not particularly limited, but is preferably about 0.2 mm or more and 3.0 mm or less, and more preferably about 0.4 mm or more and 1.6 mm or less. Thereby, it is possible to impart excellent strength to the optical sheet 15 and also impart excellent thermoformability to the optical sheet 15 when forming the optical sheet 15 into the curved optical sheet 10 having a curved shape. .

The optical sheet 15 also includes an adhesive layer as an intermediate layer between the first adhesive layer 14 and the half mirror layer 13 and at least one between the second adhesive layer 16 and the half mirror layer 13. It may be something. Thereby, it is possible to improve the adhesion between the adhesive layers 14 and 16 and the half mirror layer 13.

This adhesive layer is not particularly limited, but includes, for example, a layer mainly composed of at least one of SiO ₂ and Al ₂ O ₃ .

The optical sheet 15 of this embodiment having such a configuration can be manufactured, for example, as follows.

(Method for manufacturing optical sheet)
[1] First, the first base material 11 is prepared.
The method for manufacturing the first base material 11 is not particularly limited, and examples thereof include general molding methods such as a calendar method, an extrusion molding method such as an inflation extrusion method, and a T-die extrusion method, and a wet casting method.

Note that this first base material 11 may be one that has been subjected to a uniaxial stretching process along the machine direction (MD) of the first base material 11, or one that has been subjected to a biaxial stretching process. Furthermore, it may be one that has not been subjected to stretching treatment.

Further, in the case where the first base material 11 has been subjected to a uniaxial stretching process, the first base material 11 may have been inevitably subjected to a stretching process by the above-mentioned manufacturing method. However, it may be subjected to a stretching treatment after production.

[2] Next, the second base material 12 is prepared.
The method for manufacturing the second base material 12 is not particularly limited, but a method similar to that mentioned as the method for manufacturing the first base material 11 can be used.

Note that, like the first base material 11, this second base material 12 may be one that has been subjected to uniaxial stretching treatment along the machine direction (MD) of the first base material 11, or may be one that has been subjected to a uniaxial stretching process along the machine direction (MD) of the first base material 11, The shaft may be subjected to a stretching process or may not be subjected to a stretching process.

[3] Next, the half mirror layer 13 (multilayer laminate) is prepared.
This half mirror layer 13 (multilayer laminate) is obtained by forming a plurality of repeating parts 33 (laminates) in which high refractive index layers 31 and low refractive index layers 32 are alternately and repeatedly stacked. Specifically, for example, it can be manufactured as follows.

That is, first, as resin compositions for forming the high refractive index layer 31 and the low refractive index layer 32, a resin material having a high refractive index with respect to light in the visible light region and a resin material with a high refractive index with respect to light in the visible light region are used, respectively. On the other hand, by preparing a material containing a resin material with a low refractive index as the main material and laminating these layers alternately, a repeating section in which the high refractive index layer 31 and the low refractive index layer 32 are alternately and repeatedly laminated. 33 (laminate) is obtained (lamination step).

Methods for obtaining this repeating portion 33 are not particularly limited, but include, for example, a feed block method in which the resin material as a raw material is melt-extruded using several extruders, a coextrusion T-die method such as a multi-manifold method, Examples include an air-cooled or water-cooled coextrusion inflation method, and among them, a coextrusion T-die method is particularly preferred. The coextrusion T-die method is preferably used because it provides excellent control over the thickness of each layer formed.

Next, the repeating portion 33 (laminated body) in which the high refractive index layers 31 and the low refractive index layers 32 are alternately and repeatedly laminated is cooled, dried and solidified (cooling step). Thereby, it is possible to obtain the half mirror layer 13 that functions as a multilayer laminate (multilayer laminate reflecting plate) that selectively reflects light in the visible light region and transmits unreflected light as transmitted light.

[4] Next, adhesive is applied to both surfaces of the half mirror layer 13 formed in the step [3], and the adhesive is applied in the steps [1] and [2], respectively. With the prepared first base material 11 and second base material 12 bonded together, the adhesive is solidified. Thereby, between the half mirror layer 13 and the first base material 11 and between the half mirror layer 13 and the second base material 12, the first adhesive layer 14 and the second An adhesive layer 16 is formed.

The adhesive can be applied to the half mirror layer 13 using methods such as die coating, curtain die coating, gravure coating, comma coating, bar coating, and lip coating.

By going through the above steps [1] to [4], the first base material 11, the first adhesive layer 14, the half mirror layer 13, the second adhesive layer 16, and the first adhesive layer 14 are formed. A laminate in which the two base materials 12 are laminated in this order can be obtained as the optical sheet 15.

<Second embodiment>
Further, the optical sheet 15 may have the structure described below in addition to the structure described in the first embodiment.
FIG. 5 is a longitudinal sectional view showing a second embodiment of the optical sheet of the present invention.

Note that, hereinafter, for convenience of explanation, the upper side of FIG. 5 will be referred to as "upper" and the lower side will be referred to as "lower". In addition, the x direction in FIG. 5 is referred to as the "left-right direction," the y direction is referred to as the "front-back direction," and the z direction is referred to as the "up-down direction." Furthermore, in FIG. 5, the thickness direction of the optical sheet is exaggerated, so the dimensions are significantly different from the actual dimensions.

Hereinafter, a second embodiment of the optical sheet of the present invention will be described with reference to this figure, but the explanation will focus on the differences from the embodiments described above, and the explanation of similar matters will be omitted.

The optical sheet 15 of the present embodiment is the optical sheet of the first embodiment except that it further includes a coating layer 17 (hard coat layer) that covers the first base material 11 and the second base material 12 as the outermost layer. It is the same as 15.

That is, as shown in FIG. 5, in this embodiment, the optical sheet 15 has a coating layer 17 covering the first base material 11 as the outermost layer on one surface side (upper surface side) of the first base material 11. It also has. Further, on the other surface side (lower surface side) of the second base material 12, a coating layer 17 that covers the second base material 12 is further provided as an outermost layer. In other words, in the optical sheet 15 of this embodiment, the coating layer 17, the second base material 12, the second adhesive layer 16, the half mirror layer 13, the first adhesive layer 14, the first base material 11, and the coating layer 17 is composed of a laminate that is laminated in this order from the lower surface side to the upper surface side of the optical sheet 15.

By providing the coating layer 17 that covers the first base material 11 and the second base material 12 as in this embodiment, it is possible to reliably prevent the first base material 11 and the second base material 12 from being damaged. It can be prevented.

This coating layer 17 (coat layer) is a so-called hard coat layer formed using a resin composition, and as this resin composition, for example, one containing a silicone-modified (meth)acrylic resin is preferably used. . Therefore, a resin composition containing this silicon-modified (meth)acrylic resin will be explained below.

(Silicon-modified (meth)acrylic resin)
Silicon-modified (meth)acrylic resin (siloxane-modified (meth)acrylate) has a main chain in which constituent units derived from a (meth)acrylic monomer having a (meth)acryloyl group are repeated, and a siloxane It is a polymer (prepolymer) having repeating units (side chains) in which structural units having bonds are repeated.

That is, it is a polymer (prepolymer) in which a (meth)acrylic compound as a main chain and a compound having a siloxane bond (-Si-O-Si-) as a side chain are linked.

The silicone-modified (meth)acrylic resin has the main chain, thereby imparting excellent transparency to the coating layer 17, and also has repeating units having the siloxane bond, so that the silicone-modified (meth)acrylic resin can provide excellent transparency to the coating layer 17. The layer 17 can be provided with excellent scratch resistance and weather resistance, that is, the function as the covering layer 17 can be reliably provided.

Specifically, the main chain of the silicon-modified (meth)acrylic resin is composed of repeating structural units derived from a monomer having at least one (meth)acryloyl group of the following formula (1) and formula (2). Examples include those having the chemical formula shown in the following formula (12) as those having repeating structural units derived from both of these monomers.

(In formula (1), n represents an integer of 1 or more, R1 independently represents a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represents a hydrocarbon group or a hydrogen atom. .)

(In formula (2), m represents an integer of 1 or more, R2 independently represents a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represents a hydrocarbon group or a hydrogen atom. .)

(In formula (12), m and n represent an integer of 1 or more, R1, R2, and R3 each independently represent a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represents a carbonized (Indicates a hydrogen group or hydrogen atom.)

Further, a repeating body (side chain) in which structural units having a siloxane bond are repeated is bonded to at least one end or side chain of the main chain having such a structure.

Since siloxane bonds have high bonding strength, the silicone-modified (meth)acrylic resin has repeating bodies in which constituent units having siloxane bonds are repeated, thereby obtaining a coating layer 17 with better heat resistance and weather resistance. be able to. Further, since the bonding strength of the siloxane bonds is high, it is possible to obtain a hard coating layer 17, so that the scratch resistance of the optical sheet 15 can be further increased.

Specific examples of repeating bodies in which structural units having siloxane bonds are repeated include those constituted by repeating structural units having at least one of the siloxane bonds of the following formula (3) and formula (4). It will be done.

(In formula (3), X ₁ represents a hydrocarbon group or a hydroxyl group.)

(In formula (4), X ₂ represents a hydrocarbon group or a hydroxyl group, and X ₃ represents a divalent group in which hydrogen is removed from a hydrocarbon group or a hydroxyl group.)

Specific examples of repeating bodies in which the structural units having siloxane bonds are repeated include those having polyorganosiloxane and those having silsesquioxane. Note that the structure of silsesquioxane may be any structure such as a random structure, a cage structure, a ladder structure (ladder structure), etc.

Examples of the hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group, and isopropyl group, cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group, phenyl group, naphthyl group, etc. Examples include aryl groups such as -methylphenyl, aralkyl groups such as benzyl, diphenylmethyl, and naphthylmethyl, and biphenyl.

Moreover, it is preferable that an unsaturated double bond is introduced into the terminal or side chain of a repeating product in which structural units having a siloxane bond are repeated. As a result, when the resin composition contains urethane (meth)acrylate, which will be described later, the urethane (meth)acrylate is bonded to the (meth)acryloyl group that this urethane (meth)acrylate has, and the silicone-modified (meth)acrylic resin and urethane (meth)acrylate are bonded together. Can form a network with acrylate. Therefore, in the coating layer 17, the silicone-modified (meth)acrylic resin and the urethane (meth)acrylate are more uniformly dispersed, and as a result, the coating layer 17 can exhibit the above-mentioned properties more uniformly over its entirety. can.

The content of the silicon-modified (meth)acrylic resin in the resin composition is not particularly limited, but is preferably 5 parts by mass or more and 45 parts by mass or less, and 11 parts by mass or more, based on 100 parts by mass of the resin composition. More preferably, it is 28 parts by mass or less. If the content of the silicon-modified (meth)acrylic resin in the resin composition is less than the lower limit, the hardness of the coating layer 17 obtained from the resin composition may decrease. Furthermore, when the content of the silicon-modified (meth)acrylic resin in the resin composition exceeds the upper limit, the content of materials other than the silicon-modified (meth)acrylic resin in the resin composition decreases relatively. As a result, the flexibility of the coating layer 17 formed using the resin composition may be reduced.

Examples of the silicon-modified (meth)acrylic resin having the above structure include compounds represented by the following formulas (5) and (6).

(In formula (5), Me represents a methyl group, and m, n, and p each represent an integer of 1 or more.)

(In formula (6), Me represents a methyl group, m, n, and p each represent an integer of 1 or more; R1, R2, R3, and R4 each independently represent a hydrocarbon group, an organic group, or hydrogen atom)

(Urethane (meth)acrylate)
Moreover, it is preferable that the resin composition further contains urethane (meth)acrylate.

If an unsaturated double bond is introduced at the terminal or side chain of a repeating unit consisting of repeated structural units having a siloxane bond, which is included in a silicone-modified (meth)acrylic resin, urethane (meth)acrylate is present in the resin composition. By containing, the (meth)acryloyl group of this urethane (meth)acrylate and the unsaturated double bond bond together, forming a network between the silicone-modified (meth)acrylic resin and the urethane (meth)acrylate. Ru. As a result, the resin composition is cured and a cured product is obtained, thereby forming the coating layer 17 made of this cured product. The curing of the resin composition due to the bonding between the (meth)acryloyl group and the unsaturated double bond is carried out by photocuring, which is curing the resin composition by irradiating it with energy rays such as ultraviolet rays.

By containing urethane (meth)acrylate in the coating layer 17 formed as described above, the flexibility of the coating layer 17 can be improved, and the optical sheet 15 can be partially or completely curved. Since the optical sheet 15 is applied to objects having a shape, it is possible to accurately suppress the occurrence of cracks on the surface of the coating layer 17 when the optical sheet 15 is thermally bent, thereby imparting excellent thermoformability to the optical sheet 15. I can do it.

Furthermore, by combining the above-mentioned silicone-modified (meth)acrylic resin and this urethane (meth)acrylate, it is possible to obtain an optical sheet 15 that has both excellent scratch resistance and thermoformability. .

This urethane (meth)acrylate refers to a compound having a main chain having a urethane bond (-OCONH-) and a (meth)acryloyl group connected to this main chain. Moreover, urethane (meth)acrylate is a monomer or an oligomer.

Urethane (meth)acrylate having such a structure is a compound with excellent flexibility because it has a urethane bond. Therefore, by including the urethane (meth)acrylate in the coating layer 17, further flexibility (softness) can be imparted to the coating layer 17. Therefore, when the optical sheet 15 is formed into the curved optical sheet 10 having a curved shape, it is possible to accurately suppress the occurrence of cracks at the bent portions.

Note that this urethane (meth)acrylate can be obtained, for example, as a reaction product of an isocyanate compound obtained by reacting a polyol and a diisocyanate and a (meth)acrylate monomer having a hydroxyl group.

Further, examples of the polyol include polyether polyol, polyester polyol, and polycarbonate diol.

Further, polyester polyols can be obtained, for example, by polycondensation reaction of a diol and a dicarboxylic acid or dicarboxylic acid chloride, or by esterification of a diol or dicarboxylic acid and a transesterification reaction. Examples of dicarboxylic acids include adipic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, terephthalic acid, isophthalic acid, and phthalic acid. Examples of diols include ethylene glycol, Examples include 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and tetrapropylene glycol.

Further, examples of polycarbonate diols include reaction products of diols and carbonic esters, and examples of diols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, and tricarbonate diol. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, polyoxyethylene glycol, etc. are used, and one type or a combination of two or more types can be used.

Examples of (meth)acrylate monomers having a hydroxyl group include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, -Hydroxybutyl acrylate, polyethylene glycol monoacrylate, etc.

Further, the content of urethane (meth)acrylate in the resin composition is not particularly limited, but it is preferably 10 parts by mass or more and 75 parts by mass or less, and 17 parts by mass or more and 50 parts by mass, based on 100 parts by mass of the resin composition. More preferably, it is less than parts by mass. If the content of urethane (meth)acrylate in the resin composition is less than the lower limit, depending on the type of urethane (meth)acrylate, the flexibility of the coating layer 17 may become poor. Additionally, if the content of urethane (meth)acrylate in the resin composition exceeds the above upper limit, depending on the type of urethane (meth)acrylate, the content of materials other than urethane (meth)acrylate in the resin composition may increase. There is a possibility that the scratch resistance of the optical sheet 15 may decrease relatively.

((meth)acrylate monomer)
Moreover, it is preferable that the resin composition further contains a (meth)acrylate monomer.

If an unsaturated double bond is introduced at the end or side chain of a repeating unit consisting of repeated structural units having a siloxane bond, which is included in a silicone-modified (meth)acrylic resin, the (meth)acrylate monomer is present in the resin composition. By containing, the (meth)acryloyl group of this (meth)acrylate monomer and the unsaturated double bond bond to form a network between the silicone-modified (meth)acrylic resin and the (meth)acrylate monomer. As a result, the coating layer 17 is formed by curing the resin composition.

Examples of (meth)acrylate monomers include, but are not limited to, pentaerythritol tetraacrylate, ditrimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, and ethoxylated trimethylolpropane triacrylate. , ethoxylated pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylate, polyethylene glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated hydrogenated bisphenol A diacrylate, ethoxylated cyclohexanedimethanol diacrylate, tricyclodecane dimethanol diacrylate Acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, isobornyl acrylate, etc., and use one type or a combination of two or more of these. Can be done. Among these, from the viewpoint of improving the weather resistance of the optical sheet 15, a resin that does not contain aromatics is preferable.

The content of the (meth)acrylate monomer in the resin composition is not particularly limited, but it is preferably 15 parts by mass or more and 55 parts by mass or less, and 27 parts by mass or more and 55 parts by mass, based on 100 parts by mass of the resin composition. It is more preferable that it is below.

(Isocyanate)
Moreover, it is preferable that the resin composition further contains an isocyanate.
Thereby, in the resin composition, the isocyanate functions as a crosslinking agent that bonds (crosslinks) the silicon-modified (meth)acrylic resin intermolecularly. That is, the inclusion of isocyanate as a crosslinking agent strengthens the hydroxyl group in the main chain of the silicon-modified (meth)acrylic resin, which is a repeating structural unit derived from a (meth)acrylic monomer having a (meth)acryloyl group. The isocyanate reacts with the isocyanate group possessed by the isocyanate to form a crosslinked structure composed of urethane bonds, and as a result, a coating layer 17 composed of a cured product of the resin composition is formed. The resin composition is cured by bonding the hydroxyl group and the isocyanate group by thermosetting, which is performed by heating the resin composition.

In the coating layer 17 formed as described above, a network formed by bonding hydroxyl groups and isocyanate groups can be constructed, so that the scratch resistance and weather resistance of the coating layer 17 can be further improved. I can do it.

The content of isocyanate in the resin composition is not particularly limited, but it is preferably 3 parts by mass or more and 40 parts by mass or less, and 10 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the resin composition. is more preferable.

(Other materials)
Furthermore, the resin composition may contain other materials in addition to the various materials mentioned above.
Other materials include, but are not particularly limited to, resin materials other than the silicone-modified (meth)acrylic resin, photopolymerization initiators, ultraviolet absorbers, colorants, sensitizers, stabilizers, surfactants, oxidation Examples include inhibitors, reduction inhibitors, antistatic agents, surface conditioners, hydrophilic additives, fillers, and solvents, and one or more of these may be used in combination.

The average thickness of the coating layer 17 composed of the cured product of the resin composition as described above is not particularly limited, but is preferably 1 μm or more and 40 μm or less, more preferably 2 μm or more and 30 μm or less, and 5 μm or more. More preferably, the thickness is not less than 20 μm. If the thickness of the coating layer 17 is less than the lower limit, the weather resistance of the optical sheet 15 may deteriorate. On the other hand, if the thickness of the coating layer 17 exceeds the upper limit, when the optical sheet 15 is made into a curved optical sheet 10 having a curved shape, cracks may occur in the curved optical sheet 10 during molding of the curved optical sheet 10. may occur.

The optical sheet 15 of the second embodiment also provides the same effects as the first embodiment.

Although the optical sheet and optical component of the present invention have been described above, the present invention is not limited thereto, and each layer constituting the optical sheet 15 including the half mirror layer 13 as a reflection plate has the same function. It can be replaced with any configuration that can be used. Moreover, the optical sheet 15 may further include other layers such as an intermediate layer. Further, examples of this intermediate layer include a polarizing film that has a function of extracting linearly polarized light having a plane of polarization in one predetermined direction and polarizes the light that passes through the optical sheet 15. The polarizing film is interposed between the half mirror layer 13 and the second base material 12.

Furthermore, in the embodiment, when the optical sheet 15 of the present invention is applied to the lens 30 provided with the curved optical sheet 10 having a curved shape as a curved resin substrate, that is, the optical component of the present invention is applied to the lens 30. For example, cover films for display devices such as liquid crystal displays and head-up displays, transportation means such as motorcycles, cars, airplanes, and trains, machine tools, and windows for buildings. The optical sheet 15 is used by attaching it to components, cover members of headlights and fog lamps, brightness enhancement films and cold mirrors provided in light sources of head-up displays, reflective plates of in-vehicle sensors such as infrared sensors, etc. You can also. In addition, in these cases, an optical component is constituted by a cover film, a window member, a cover member, a brightness enhancement film, a cold mirror, or a reflecting plate, and the curved optical sheet 10 attached thereto.

Hereinafter, the present invention will be explained more specifically based on Examples. Note that the present invention is not limited in any way by these Examples.

1. Preparation of raw materials <Polycarbonate (PC1)>
Iupilon E2000 (manufactured by Mitsubishi Engineering Plastics) was prepared as polycarbonate (PC1).

<Polymethyl methacrylate (heat-resistant PMMA1)>
Delpet PM120N (manufactured by Asahi Kasei Corporation) was prepared as polymethyl methacrylate (heat-resistant PMMA1).

<Polyethylene terephthalate (heat-resistant PETG1)>
Tritan TX2001 (manufactured by Eastman Chemical Company, glycol-modified polyethylene terephthalate) was prepared as heat-resistant amorphous polyethylene terephthalate (heat-resistant PETG1).

<Polyethylene terephthalate (PETG2)>
Sky Green K2012 (manufactured by SK Chemicals) was prepared as an amorphous polyethylene terephthalate copolymer (PETG2).

<Polyarylate (PAR1)>
U polymer P-5001 (manufactured by Unitika) was prepared as polyarylate (PAR1).

<Polyether sulfone (PES1)>
Sumika Excel 3600G (manufactured by Sumitomo Chemical Co., Ltd.) was prepared as polyether sulfone (PES1).

<Polyethylene naphthalate (PEN1)>
Teonex TN8065S (manufactured by Teijin) was prepared as polyethylene naphthalate (PEN1).

<Polyethylene terephthalate (APET1)>
Novapex GM700Z (manufactured by Mitsubishi Chemical Corporation, crystalline polyethylene terephthalate) was prepared as polyethylene terephthalate (APET1).

<Acrylonitrile-styrene copolymer (AS1)>
Denka AS-XGS (manufactured by Denka Corporation) was prepared as an acrylonitrile-styrene copolymer (AS1).

<Styrene-N-phenylmaleimide-maleic anhydride copolymer (IP1)>
Denka IP-ND (manufactured by Denka Corporation) was prepared as the styrene-N-phenylmaleimide-maleic anhydride copolymer (IP1).

<Silicone adhesive>
As the silicone adhesive, a liquid heat-curable silicone adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., "KER-2937A, B") was prepared.

2. Production of optical sheet (Example 1)
[1] First, by extrusion molding 100 parts by mass of polycarbonate (PC1), two base materials of the same thickness (thickness 0.3 mm) are obtained, and these are used as the first base material 11 and the second base material 11. Material 12 was used.

[2] Next, polycarbonate (PC1) was used as a resin material for forming the high refractive index layer 31, and polymethyl methacrylate (heat-resistant PMMA1) was used as a resin material for forming the low refractive index layer 32, respectively. Prepared.

[3] Next, polycarbonate (PC1, Tg 150°C) and polymethyl methacrylate (heat-resistant PMMA1, Tg 123°C) were heated at 270°C using an extruder ("SNT40-28", manufactured by Sun NT), respectively. The high refractive index layer 31 and the low refractive index layer 32 were alternately and repeatedly laminated by forming a film by coextruding it using a feed block and die and cooling it. , a half mirror layer 13 was obtained which was composed of a laminate (multilayer laminate) with a total of 1023 layers (repetition number 511 times). Here, the ejection amount was adjusted so that the laminated thickness ratio was high refractive index layer 31:low refractive index layer 32=1:1.

In addition, in the obtained half mirror layer 13, the refractive index of the low refractive index layer 32 at a wavelength of 589 nm was measured using an Appe refractometer (manufactured by ATAGO, "NA-1T SOLID") and found to be 1.510. there were. Further, the refractive index of the high refractive index layer 31 at a wavelength of 589 nm was measured using an Appe refractometer (manufactured by ATAGO, "NA-1T SOLID") and found to be 1.585. Furthermore, the average thickness of the half mirror layer 13 was 100 μm.

[4] Next, on both surfaces of the half mirror layer 13, a coating film made of silicone adhesive is applied so that the thickness of the adhesive layers 14 and 16 formed after curing is 50 μm, respectively. was coated.

Then, the first base material 11 and the second base material 12 are bonded together so as to be in contact with the coating films formed on both surfaces of the half mirror layer 13, and then at a temperature of 100° C. for 1 time. After primary heating for 0.0 hr, the coating film was cured by secondary heating at 120°C for 2.0 hr, and then coated for 7 days in an environment of 25°C and 50% RH. By curing the film, the first adhesive layer 14 and the second adhesive layer are formed between the first base material 11 and the half mirror layer 13 and between the second base material 12 and the half mirror layer 13, respectively. A coating layer 16 was formed.
The optical sheet 15 of Example 1 was obtained through the steps [1] to [4] as described above.

(Examples 2 to 5, Comparative Examples 1 to 3)
In the step [1], the resin materials shown in Table 1 were prepared as resin materials for forming the first base material 11, the second base material 12, the high refractive index layer 31, and the low refractive index layer 32, respectively. In addition, Examples 2 to 5 and Comparative Example were prepared in the same manner as in Example 1 except that the half mirror layer 13 obtained in the step [3] was subjected to a stretching process in the MD as necessary. Optical sheets 15 of Nos. 1 to 3 were obtained.

3. Evaluation The optical sheet 15 of each Example and each Comparative Example was evaluated by the following method.
<1A> Measurement of reflectance R1 (%) of curved optical sheet 10 before heating First, optical sheets 15 of each example and each comparative example were measured at the higher of glass transition point Tg1 and glass transition point Tg2. By pressing the optical sheet 15 (laminated body) against a metal mold at a temperature 10° C. higher than the glass transition point of .

Next, the curved optical sheet 10 is placed between the light source that emits light of 589 nm and the light receiving section so that the angle between the top surface of the curved optical sheet and the straight line connecting the light source and the light receiving section is 90°. did.

Next, the light emitted from the light source (transmitted light) that has passed through the curved optical sheet 10 is received by the light receiving section, and the transmittance (%) of this transmitted light is measured to determine the initial (before heating) state. The reflectance R1 (%) was determined.

<2A> Measurement of reflectance R2 (%) of curved optical sheet 10 after heating First, optical sheets 15 of each example and each comparative example were measured at the higher of glass transition point Tg1 and glass transition point Tg2. By pressing the optical sheet 15 (laminated body) against a metal mold at a temperature 10° C. higher than the glass transition point of .

Next, the curved optical sheet 10 is stored in a thermal circulation oven at a temperature of 105° C. for 1000 hours, and then the upper surface of the curved optical sheet 10 is placed between the light source that emits light of 589 nm and the light receiving section. It was arranged so that the angle formed between the light receiving part and the straight line connecting the light receiving part was 90°.

Next, the light emitted from the light source (transmitted light) that has passed through the curved optical sheet 10 is received by the light receiving section, and the transmittance (%) of this transmitted light is measured to determine the reflectance R2 after heating. (%) was calculated.

Then, using the reflectance R2 (%) after heating obtained here and the initial (before heating) reflectance R1 (%) obtained in <1A> above, reflectance retention ( R2/R1×100 [%]) was calculated.

<3A> Confirmation of heat resistance of optical sheet in visible light region First, the reflectance at a wavelength of 590 nm was measured for the optical sheet 15 of each Example and each Comparative Example. Thereafter, a durability test (105°C x 1000 hr) was conducted, and the reflectance of the sample (optical sheet) after the test was similarly measured.

Then, assuming that the reflectances before and after the durability test were R3 and R4, respectively, the rate of change in reflectance was determined based on these as shown below.

Rate of change in reflectance: R4/R3×100 (%)
Thereafter, the rate of change in the obtained reflectance was evaluated based on the evaluation criteria shown below.

[Evaluation criteria]
◎: R4/R3×100 is 85% or more ○: R4/R3×100 is 80% or more and less than 85% ×: R4/R3×100 is less than 80%

<5A> Confirmation of thermal bendability of optical sheets First, for the optical sheets of each example and each comparative example, the glass transition point is 10° C. higher than the higher of the glass transition point Tg1 and the glass transition point Tg2. Heat bending was performed by pressing the sample against a metal mold with a radius of curvature of 60 mm while the sample was heated to a certain temperature.
Then, the thermally bent curved optical sheet 10 was stored in a thermal circulation oven at a temperature of 105° C. for 1000 hours, and the radius of curvature was then measured and evaluated based on the evaluation criteria shown below.

[Evaluation criteria]
After being stored in a heat circulation oven at a temperature of 105°C for 1000 hours, the number of items that maintain a radius of curvature of 60 ± 5 mm is
◎: 50 out of 50 curved optical sheets ○: 48 or more but less than 50 out of 50 curved optical sheets ×: Less than 48 out of 50 curved optical sheets

The evaluation results for the optical sheets of each Example and each Comparative Example obtained as described above are shown in Table 1 below.

As shown in Table 1, the optical sheets in each example satisfied Tg1, Tg2 ≧ 105°C, and therefore exhibited excellent reflectivity in the visible light region before the heat resistance test. Furthermore, the results showed that the reflectivity in the visible light region could be maintained before and after the heat resistance test, that is, the results could be said to have heat resistance. Moreover, the results showed that it can be said that it has excellent workability.

On the other hand, the optical sheets in each comparative example do not satisfy Tg1, Tg2≧105°C, and therefore cannot be said to have excellent heat resistance in the visible light region. showed that.

10 Curved optical sheet 11 First base material 12 Second base material 13 Half mirror layer 14 First adhesive layer 15 Optical sheet 16 Second adhesive layer 17 Covering layer 20 Frame 21 Rim portion 22 Bridge portion 23 Temple portion 24 Nose pad Part 30 Lens 31 High refractive index layer 32 Low refractive index layer 33 Repeated part 35 Resin layer 40 Mold 50 Protective film 100 Sunglasses 150 Multilayer laminate 200 Curved multilayer laminate

Claims (10)

a first base material mainly composed of a resin material having light transmittance;
a half mirror layer provided on one surface side of the first base material and comprising a laminate in which high refractive index layers and low refractive index layers are alternately and repeatedly laminated;
An optical sheet made of the resin material as a main material and comprising a second base material provided on the opposite side of the first base material of the half mirror layer,
In the half mirror layer, the refractive index of the high refractive index layer is higher than the refractive index of the low refractive index layer,
When the glass transition point of the main material constituting the high refractive index layer is Tg1, and the glass transition point of the main material constituting the low refractive index layer is Tg2, Tg1, Tg2 ≧ 105 ° C. optical sheet. The refractive index difference (N1-N2), where the refractive index of the high refractive index layer at a wavelength of 589 nm is N1 and the refractive index of the low refractive index layer at a wavelength of 589 nm is N2, is 0.05 or more. The optical sheet according to claim 1, which has a particle size of 25 or less. The optical sheet according to claim 1 or 2, wherein the high refractive index layer and the low refractive index layer each have an average thickness of 50 nm or more and 300 nm or less. In the half mirror layer, the number of repetitions in which the high refractive index layer and the low refractive index layer are alternately and repeatedly stacked is 50 to 750 times, according to any one of claims 1 to 3. optical sheet. The optical sheet according to any one of claims 1 to 4, wherein the half mirror layer has a thickness direction retardation (Rth) of 500 nm or less at a wavelength of 589 nm. The optical sheet according to any one of claims 1 to 5, wherein the glass transition point Tg1 and the glass transition point Tg2 satisfy the following relationship: 0°C≦|Tg1−Tg2|≦60°C. The optical sheet according to any one of claims 1 to 6, wherein the lower glass transition point of the glass transition point Tg1 and the glass transition point Tg2 is 110°C or more and 250°C or less. When the optical sheet is made into a curved optical sheet having a curved shape with a radius of curvature of 60 mm at a temperature 10° C. higher than the higher glass transition point of the glass transition point Tg1 and the glass transition point Tg2. The reflectance of the curved optical sheet for light with a wavelength of 589 nm is R1 [%],
After storing the curved optical sheet in a thermal circulation oven at a temperature of 105° C. for 1000 hours, when the reflectance of the curved optical sheet for light at a wavelength of 589 nm is R2 [%], R2/R1× The optical sheet according to any one of claims 1 to 7, wherein the reflectance retention property determined by 100% is 80% or more. The optical sheet is formed into a curved optical sheet having a curved shape with a radius of curvature of 60 mm at a temperature 10° C. higher than the higher glass transition point of the glass transition point Tg1 and the glass transition point Tg2. 4. The number of curved optical sheets whose radius of curvature maintains a size of 60±5 mm after being stored in an oven at a temperature of 105° C. for 1000 hours is 48 or more out of 50 curved optical sheets. 9. The optical sheet according to any one of 1 to 8. An optical component comprising the optical sheet according to any one of claims 1 to 9.

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