JP2021081698A - Resin panel and infrared sensor - Google Patents

Abstract

To provide a resin panel which allows an infrared sensor to function sufficiently when used as a protective cover for the infrared sensor.SOLUTION: A resin panel 100 provided herein comprises at least a core layer 10 containing a polycarbonate resin and one or more compounds selected from azomethine-azo compounds and perylene compounds. The resin panel 100 has a light transmittance of 85% or greater for a 905 nm-wavelength and a visible light transmittance of 20% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resin panel and an infrared sensor.

In recent years, technological development of optical sensors such as LiDAR has been progressing in fields such as automatic driving of automobiles. In these optical sensors, a protective cover may be arranged in front of the light emitting element and the light receiving element.

The protective cover of the optical sensor is formed, for example, to protect the light emitting element and the light receiving element from flying stones, sunlight, wind and rain, and the like. Therefore, it is preferable that the protective cover has excellent impact resistance and weather resistance. For example, Patent Document 1 proposes arranging an optical element made of polycarbonate as a protective cover.

JP-A-2019-32505 (Claim 1, paragraph 0042)

Some light emitting elements of an optical sensor use light in the infrared region as an emission wavelength in order to suppress the influence on the human eye. In particular, many of the light emitting elements of optical sensors (mainly LiDAR) mounted on automobiles use light in the infrared region as the light emitting wavelength.
However, when an optical element made of polycarbonate disclosed in Patent Document 1 is applied as a protective cover for an optical sensor (infrared sensor) whose emission wavelength is light in the infrared region, the infrared sensor often does not function sufficiently. .. In particular, when a design layer is applied to the protective cover in order to enhance the design, there is a tendency that the infrared sensor does not function sufficiently in many cases.

An object of the present invention is to provide a resin panel capable of fully functioning the infrared sensor when applied as a protective cover for the infrared sensor, and an infrared sensor having the resin panel.

In order to solve the above problems, the present invention provides the following [1] to [2].
[1] A resin panel having at least a core layer, wherein the resin panel has a light transmittance of 85% or more and a visible light transmittance of 20% or less at a wavelength of 905 nm.
[2] An infrared sensor having an infrared light emitting element, an infrared light receiving element, and a protective cover arranged in front of the infrared light emitting element and the infrared light receiving element, wherein the protective cover is the resin of the above [1]. An infrared sensor that is a panel.

The resin panel of the present invention can fully function the infrared sensor when applied as a protective cover for the infrared sensor. In addition, the infrared sensor of the present invention having the resin panel can fully function the infrared sensor.

It is sectional drawing which shows one Embodiment of the resin panel of this invention. It is sectional drawing which shows the other embodiment of the resin panel of this invention. It is sectional drawing which shows the other embodiment of the resin panel of this invention. It is sectional drawing which shows the other embodiment of the resin panel of this invention. It is sectional drawing which shows the other embodiment of the resin panel of this invention. It is sectional drawing which shows the other embodiment of the resin panel of this invention.

[Resin panel]
The resin panel of the present invention is a resin panel having at least a core layer, and the resin panel has a light transmittance of 85% or more and a visible light transmittance of 20% or less at a wavelength of 905 nm.

1 to 6 are cross-sectional views showing an embodiment of the resin panel of the present invention.
Each of the resin panels (100) shown in FIGS. 1 to 6 has a core layer (10).
Further, the resin panel (100) of FIGS. 1 to 6 has an inner layer (20) in addition to the core layer (10), and has an antireflection layer (23) and the like as the inner layer (20). doing.
Further, the resin panel (100) of FIGS. 1 to 5 has an outer layer (30) in addition to the core layer (10), and the hard coat layer B (35) or the like is used as the outer layer (30). Have.

In the present specification, the "inner layer" means a layer located on the infrared emitting element and the infrared receiving element side with respect to the core layer when the resin panel is applied as a protective cover for the infrared sensor. To do. Similarly, in the present specification, the "outer layer" is a layer located on the opposite side of the infrared light emitting element and the infrared light receiving element with respect to the core layer when the resin panel is applied as a protective cover for the infrared sensor. Means that.

<Transmittance>
The resin panel of the present invention is required to have a light transmittance of 85% or more at a wavelength of 905 nm and a visible light transmittance of 20% or less. It is necessary to satisfy the above-mentioned numerical values regardless of which of the front and back surfaces of the resin panel is used as the light incident surface.

When the light transmittance at a wavelength of 905 nm is less than 85%, the detection function of an infrared sensor whose emission wavelength is infrared rays having a wavelength of 905 nm cannot be sufficiently applied. Further, even if the light transmittance at a wavelength of 905 nm is 85% or more, if the visible light transmittance exceeds 20%, a malfunction based on visible light such as sunlight may occur, and the infrared sensor may malfunction. The function cannot work sufficiently. Further, by setting the visible light transmittance to 20% or less, the infrared light emitting element and the infrared light receiving element arranged inside the infrared sensor can be easily invisible.

The light transmittance of the resin panel at a wavelength of 905 nm is preferably 86% or more, and more preferably 88% or more. The upper limit of the light transmittance of the resin panel at a wavelength of 905 nm is not particularly limited, but is usually 97% or less.

In order to increase the light transmittance of the resin panel at a wavelength of 905 nm, it is preferable to have a low-reflection layer described later, and it is more preferable to set the refractive index and thickness of the low-reflection layer in the range described later.

In the present specification, the light transmittance of the resin panel at a wavelength of 905 nm and the visible light transmittance described later are taken as the average value of the measured values at 20 points.

The visible light transmittance of the resin panel is preferably 15% or less, more preferably 13% or less, and further preferably 11% or less.
Carbon black is usually used to reduce the visible light transmittance. However, since carbon black absorbs light in the infrared region, it lowers the light transmittance at a wavelength of 905 nm. Therefore, in order to reduce the visible light transmittance of the resin panel, it is preferable to use one or more compounds selected from the azomethine azo compound and the perylene compound described later.

Even if the visible light transmittance is made too low, it is difficult to obtain a further effect, but the light transmittance at a wavelength of 905 nm may decrease. Therefore, the visible light transmittance of the resin panel is preferably 1% or more, and more preferably 2% or more.

In the present specification, the "visible light transmittance" means the average value of the spectral transmittances having a wavelength of 380 to 780 nm. The measurement wavelength interval is 1 nm.

<Core layer>
The core layer preferably contains resin or glass as a main component, and more preferably contains resin as a main component from the viewpoint of moldability.
The main component means 50% by mass or more of the total solid content constituting the core layer, preferably 70% by mass or more, and more preferably 90% by mass or more.

When the core layer contains a resin, a thermoplastic resin is preferable from the viewpoint of ease of injection molding such as insert molding and in-mold molding.
The thermoplastic resins include polystyrene-based resins, polyolefin-based resins, ABS resins, AS resins, AN resins, polyphenylene oxide-based resins, polycarbonate-based resins, polyacetal-based resins, acrylic-based resins, polyethylene terephthalate-based resins, and polybutylene tephthalate-based resins. Examples thereof include one or a mixture selected from resins, polysulfone-based resins, and polyphenylene sulfide-based resins. Among these, polycarbonate-based resins and acrylic-based resins are preferable, and polycarbonate-based resins having excellent impact resistance are more preferable.

-Azomethine azo compounds, perylene compounds-
The core layer preferably contains one or more compounds selected from azomethine azo compounds and perylene compounds. Azomethine Azo-based compounds and perylene-based compounds are black pigments and have a property of transmitting light in the infrared region while absorbing light in the visible light region. Therefore, by containing one or more compounds selected from the azomethine azo compound and the perylene compound in the core layer, it is easy to maintain the light transmittance at a wavelength of 905 nm in a high range while lowering the visible light transmittance of the resin panel. it can.

Azomethine The azo compound is an azo compound having an azomethine group. Examples of the azo compound having an azomethine group include a compound having an azo group having a structural unit represented by the following general formula (1) in the molecule.
The azomethine azo compound can be produced, for example, by the method described in JP-A-63-921283 and JP-A-62-32149.
Further, examples of the azomethine azo compound include a compound having a diazonium group which is a reaction compound of tetrachlorophthalimide and aminoaniline.

［式（１）中、「Ａｒ」は芳香族化合物又は複素環式化合物の残基であり、「Ｘ」は水素原子又はハロゲン原子であり、「ｍ」はＡｒの置換位置に起因する１以上の整数である。「ｍ」は好ましくは１〜４の整数である。］

[In formula (1), "Ar" is a residue of an aromatic compound or a heterocyclic compound, "X" is a hydrogen atom or a halogen atom, and "m" is one or more due to the substitution position of Ar. Is an integer of. "M" is preferably an integer of 1 to 4. ]

The perylene-based compound is a compound having a structure in which two oxygen atoms constituting the six-membered ring of perylenetetracarboxylic dianhydride are removed, and examples thereof include perylene black.

The content of one or more compounds selected from the azomethine azo compound and the perylene compound in the core layer varies depending on the thickness of the core layer, the composition of the design layer described later, and the like. The total solid content is preferably 45% by mass or less, and more preferably 5 to 30% by mass.

The core layer may contain additives such as an ultraviolet absorber, a light stabilizer, an antioxidant and a flame retardant, if necessary.

The thickness of the core layer is not particularly limited, but is usually 1 mm or more, preferably 1 to 10 mm.
In the present specification, the thickness of each layer (core layer, design layer, etc.) constituting the resin panel is calculated as an average value of 20 arbitrary points when the vertical cross section of the resin panel is observed with an electron microscope or the like. ..

<Anti-reflective layer>
The resin panel of the present invention preferably has an antireflection layer arranged on the surface on at least one side. The antireflection layer is preferably arranged on at least the surface on the inner layer side of the resin panel, and may be arranged on both surfaces of the resin panel. Considering that excellent scratch resistance is required on the outer layer side of the resin panel, it is also preferable to arrange the antireflection layer only on the surface on the inner layer side of the resin panel.
The general antireflection layer is designed so that the reflectance in the vicinity of 550 nm, which is the central wavelength of the visible light region, is the lowest. The antireflection layer of the present embodiment preferably has the lowest reflectance in the vicinity of a wavelength of 905 nm.

Examples of the antireflection layer include a single-layer structure of a low refractive index layer and a two-layer structure of a high refractive index layer and a low refractive index layer, and an antireflection layer may be further formed by three or more layers. In the case of a two-layer structure consisting of a high refractive index layer and a low refractive index layer, the low refractive index layer is arranged on the surface side (= the high refractive index layer is on the core layer side).
The total thickness of the antireflection layer may be adjusted so that the reflectance in the vicinity of the wavelength of 905 nm is low for each configuration of the antireflection layer (single layer, two layers, three layers or more). The total thickness of the antireflection layer is, for example, about 120 to 550 nm, preferably about 170 to 450 nm.

-Low refractive index layer-
The refractive index of the low refractive index layer is preferably 1.28 to 1.40, more preferably 1.30 to 1.38.
The thickness of the low refractive index layer is preferably 120 to 250 nm, more preferably 120 to 200 nm, and even more preferably 150 to 200 nm.
By setting the refractive index and the thickness of the low refractive index layer in the above range, it is possible to easily make the reflectance in the vicinity of the wavelength of 905 nm the lowest.

The method for forming the low refractive index layer can be roughly divided into a wet method and a dry method. As the wet method, a method of forming by a sol-gel method using a metal alkoxide or the like, a method of coating a resin having a low refractive index such as a fluororesin to form the resin, or a low refractive index particles contained in the resin composition. A method of forming by applying a coating liquid for forming a refractive index layer can be mentioned. Examples of the dry method include a method of selecting particles having a desired refractive index from low refractive index particles described later and forming them by a physical vapor deposition method or a chemical vapor deposition method.
The wet method is excellent in terms of production efficiency, and among the wet methods, it is preferably formed by a coating liquid for forming a low refractive index layer in which low refractive index particles are contained in the binder resin composition.

The low refractive index particles can be used without limitation whether they are particles made of an inorganic compound such as silica or magnesium fluoride or particles made of an organic compound, but from the viewpoint of improving the antireflection property by lowering the refractive index. Therefore, particles having a structure having voids are preferably used.
Particles having a structure having voids have fine voids inside, and are filled with a gas such as air having a refractive index of 1.0, so that the particles themselves have a low refractive index. There is. Examples of the particles having such voids include inorganic or organic porous particles and hollow particles. For example, porous polymer particles using porous silica, hollow silica particles, acrylic resin and the like. And hollow polymer particles.
The average particle size of the primary particles of the low refractive index particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and even more preferably 10 to 80 nm.

The content of the low refractive index particles is preferably 50 to 200 parts by mass, and more preferably 70 to 150 parts by mass with respect to 100 parts by mass of the binder component.

The binder resin composition is preferably a curable resin composition. The curable resin composition becomes a cured product in the antireflection layer and becomes a binder component.
Examples of the curable resin composition include a thermosetting resin composition and an ionizing radiation curable resin composition, and among these, an ionizing radiation curable resin composition is preferable.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating. Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. To the thermosetting resin composition, a curing agent such as an isocyanate-based curing agent is added to these curable resins, if necessary.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter, also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group and an allyl group, and an epoxy group and an oxetanyl group.
As the ionizing radiation curable resin, a compound having an ethylenically unsaturated bond group is preferable. Further, from the viewpoint of suppressing damage to the resin layer in the process of producing the transfer sheet, as the ionizing thermosetting resin, a compound having two or more ethylenically unsaturated bonding groups is more preferable, and among them, ethylenically unsaturated. A polyfunctional (meth) acrylate compound having two or more saturated bond groups is more preferable. As the polyfunctional (meth) acrylate compound, either a monomer or an oligomer can be used.
Note that ionizing radiation means electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or cross-linking molecules, and usually ultraviolet rays (UV) or electron beams (EB) are used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion rays can also be used.

Among the polyfunctional (meth) acrylate-based compounds, the bifunctional (meth) acrylate-based monomers include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexane. Examples thereof include diol diacrylate.
Examples of the trifunctional or higher functional (meth) acrylate-based monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and di. Examples thereof include pentaerythritol tetra (meth) acrylate and isocyanuric acid-modified tri (meth) acrylate.
Further, the (meth) acrylate-based monomer may be one in which a part of the molecular skeleton is modified, and is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol and the like. Can also be used.

Examples of the polyfunctional (meth) acrylate-based oligomer include acrylate-based polymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate.
Urethane (meth) acrylate is obtained, for example, by reacting a polyhydric alcohol or an organic diisocyanate with a hydroxy (meth) acrylate.
Further, the preferable epoxy (meth) acrylate is a (meth) acrylate obtained by reacting a (meth) acrylic acid with a trifunctional or higher functional aromatic epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin or the like, and a bifunctional epoxy resin. (Meta) acrylate obtained by reacting the above aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with polybasic acid and (meth) acrylic acid, and bifunctional or higher functional aromatic epoxy resin, It is a (meth) acrylate obtained by reacting an alicyclic epoxy resin, an aliphatic epoxy resin or the like with phenols and (meth) acrylic acid.
The ionizing radiation curable resin may be used alone or in combination of two or more.

When the ionizing radiation curable resin is an ultraviolet curable resin, the coating liquid for forming the resin layer preferably contains an additive such as a photopolymerization initiator or a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyl oxime ester, thioxanthones and the like.
Further, the photopolymerization accelerator can reduce the polymerization inhibition by air at the time of curing and accelerate the curing rate. For example, from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester and the like. One or more selected species can be mentioned.

The low refractive index layer preferably contains a water repellent. Since the low refractive index layer contains a water repellent, dew condensation on the inside of the resin panel can be suppressed, and deterioration of the function of the infrared sensor due to dew condensation can be suppressed.
Examples of the water repellent include fluorine compounds. The content of the water repellent is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, based on the total solid content of the low refractive index layer.

-High refractive index layer-
The antireflection layer may further have a high refractive index layer. By having the high refractive index layer in addition to the low refractive index layer, the wavelength region having low reflectance is widened, and the applicable range of the wavelength of the infrared laser can be widened. Further, the peak of the reflectance near 905 nm can be sharpened, and by increasing the reflectance of other wavelengths, it becomes possible to cut other wavelengths that become noise.
The high refractive index layer is arranged closer to the core layer than the low refractive index layer.

The high refractive index layer preferably has a refractive index of 1.55 to 1.85, more preferably 1.56 to 1.70.
The thickness of the high refractive index layer is preferably 300 nm or less, and more preferably 20 to 250 nm.

The high refractive index layer can be formed from, for example, a high refractive index layer coating liquid containing a binder resin composition and high refractive index particles. As the binder resin composition, for example, the curable resin composition exemplified in the low refractive index layer can be used.

Examples of high refractive index particles include antimony pentoxide (1.79), zinc oxide (1.90), titanium oxide (2.3 to 2.7), cerium oxide (1.95), and tin-doped indium oxide (1. 95-2.00), antimony-doped tin oxide (1.75-1.85), yttrium oxide (1.87), zirconium oxide (2.10) and the like.
The average particle size of the primary particles of the high refractive index particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and even more preferably 10 to 80 nm.

-Contact angle-
The water contact angle on the surface of the antireflection layer is preferably 100 degrees or more, and more preferably 105 degrees or more. By setting the contact angle within this range, dew condensation inside the resin panel can be suppressed, and deterioration of the function of the infrared sensor due to dew condensation can be suppressed.
In the present specification, the "water contact angle" means that 1.5 μL of pure water is dropped and the static contact angle 2 seconds after the drip is measured according to the θ / 2 method.

<Other layer 1 (layer located between the core layer and the antireflection layer)>
The core layer and the antireflection layer may be in direct contact with each other, but it is preferable that the core layer and the antireflection layer are in close contact with each other via another layer.
Examples of the layer located between the core layer and the antireflection layer include a base material A, an adhesive layer A, and a hard coat layer A. Further, another layer such as a design layer and a primer layer exemplified as an outer layer may be provided between the core layer and the antireflection layer.

As shown in FIGS. 1 and 4, when the base material A (22) and the adhesive layer A (21) are provided between the antireflection layer (23) and the core layer (10) (≈ the inner layer (20)). When the adhesive layer A (21) and the base material A (22) are provided), it is preferable to laminate the inner layer (20) on the core layer (10) so that the core layer and the inner layer are brought into close contact with each other.
As shown in FIGS. 2 and 5, when the base material A (22) is provided between the antireflection layer (23) and the core layer (10) (≈ the inner layer (20), the base material A (22) is used. However, it is preferable that the core layer (10) and the inner layer (20) are brought into close contact with each other by insert molding (when the adhesive layer A (21) is not provided).
As shown in FIG. 3, when the adhesive layer A (21) is provided between the antireflection layer (23) and the core layer (10) (≈ the inner layer (20) is provided with the adhesive layer A (21). In-mold using a base material A (22)) and a transfer sheet (a transfer sheet having a transfer layer (inner layer) including an antireflection layer and an adhesive layer A on a release base material). It is preferable that the core layer (10) and the inner layer (20) are brought into close contact with each other by molding.

-Base material A-
Examples of the base material A include polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene / vinyl acetate copolymers, vinyl resins such as ethylene / vinyl alcohol copolymers, polyethylene terephthalates, and the like. Represented by polyester resins such as polyethylene naphthalate and polybutylene terephthalate, acrylic resins such as methyl poly (meth) acrylate and ethyl poly (meth) acrylate, styrene resins such as polystyrene, nylon 6 or nylon 66, etc. Examples thereof include a plastic film made of a resin such as a polyamide resin.
Among these plastic films, biaxially stretched polyester film is preferable from the viewpoint of heat resistance and dimensional stability, and acrylic film, polycarbonate film, or acrylic and polycarbonate are used from the viewpoint of moldability such as insert molding and weather resistance. The co-extruded product of is preferable.

The thickness of the base material A is preferably 28 to 250 μm, more preferably 38 to 200 μm, from the viewpoint of moldability, handleability, and the like.

-Adhesive layer A-
The adhesive layer A is preferably arranged at a position in contact with the core layer.
The adhesive layer A may be a pressure-sensitive adhesive layer (so-called “adhesive layer”) or a heat-sensitive adhesive layer (so-called “heat seal layer”). When performing the above-mentioned lamination, a pressure-sensitive adhesive layer (adhesive layer) is preferable, and when performing the above-mentioned in-mold molding, a heat-sensitive adhesive layer (heat seal layer) is preferable.

Further, it is preferable to use a heat-sensitive or pressure-sensitive resin suitable for the material of the core layer for the adhesive layer A. For example, when the material of the core layer is an acrylic resin, it is preferable to use an acrylic resin. When the material of the core layer is a polyphenylene oxide-based resin, a polycarbonate-based resin, or a styrene-based resin, it is preferable to use an acrylic resin, a polystyrene-based resin, a polyamide-based resin, or the like having an affinity for these resins. Further, when the material of the core layer is polypropylene resin, it is preferable to use chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, cyclized rubber, and kumaron indene resin.

The thickness of the adhesive layer A is preferably 0.1 to 50 μm, more preferably 0.5 to 30 μm.

-Hard coat layer A-
The hard coat layer A is preferably arranged on the core layer side of the antireflection layer and at a position in contact with the antireflection layer.
By arranging the hard coat layer A at such a position, it is possible to prevent the surface of the antireflection layer from being damaged when manufacturing the resin panel or when incorporating the resin panel into the infrared sensor, and to maintain the desired transmittance for a long period of time. Can be easily maintained. Further, by arranging the hard coat layer A at such a position, the infrared transmittance can be further increased by adjusting the refractive index of the hard coat layer A.

The hard coat layer A preferably contains a cured product of the curable resin composition as a main component.
The main component means 50% by mass or more of the total solid content constituting the hard coat layer A, preferably 70% by mass or more, and more preferably 80% by mass or more.

Examples of the curable resin composition of the hard coat layer A include a thermosetting resin composition and an ionizing radiation curable resin composition, and an ionizing radiation curable resin composition is preferable.
Examples of the thermosetting resin composition and the ionizing radiation curable resin composition of the hard coat layer A include the same as the thermosetting resin composition and the ionizing radiation curable resin composition of the low refractive index layer.

The hard coat layer A may contain inorganic particles in order to increase the hardness.
Examples of the inorganic particles include silica, alumina, zirconia, titania and the like, and silica is preferable.

The average particle size of the inorganic particles is preferably 10 nm to 6 μm, more preferably 30 nm to 5 μm.
In the present specification, the average particle size is measured as a mass average value d50 in the particle size distribution measurement by the laser light diffraction method.

The content of the inorganic particles in the hard coat layer A is preferably 0.1 to 30 parts by mass, and preferably 1 to 20 parts by mass with respect to 100 parts by mass of the cured product of the curable resin composition. More preferred.

The thickness of the hard coat layer A is preferably 1 to 20 μm, more preferably 2 to 10 μm, and even more preferably 3 to 5 μm.

<Design layer>
The resin panel of the present invention may have a design layer.
When the resin panel has an antireflection layer, the design layer is preferably located between the antireflection layer and the core layer, or on the side opposite to the antireflection layer of the core layer, and above all, the antireflection of the core layer. More preferably, it is located on the opposite side of the layer.
That is, in the embodiment having the antireflection layer and the design layer, the resin panel has the design layer, the core layer, and the antireflection layer in this order, and the antireflection layer is arranged on the surface of the resin panel. preferable.

The design layer preferably contains a binder resin and a colorant.
Examples of the binder resin for the design layer include a thermoplastic resin, a cured product of a thermosetting resin composition, and a cured product of an ionizing radiation curable resin composition, and adjacent layers (for example, base material B, primer layer, and hard material) are used. From the viewpoint of improving the adhesion with the coat layer B), it is preferable to appropriately select the layer according to the composition of the adjacent layer. For example, it is preferable to include a thermoplastic resin as the binder resin because it is easy to improve the adhesion with various layers. When the adjacent layer is formed from a thermosetting resin composition, the binder resin of the design layer is preferably formed from the thermosetting resin composition (the adjacent layer is a cured product of the thermosetting resin composition). When, the binder resin of the design layer preferably contains a cured product of the thermosetting resin composition).
The thermoplastic resin and the thermosetting resin composition as the binder resin of the design layer are the same as those exemplified as the thermoplastic resin of the core layer and the thermosetting resin composition of the low refractive index layer. Can be mentioned.

The colorant for the design layer is preferably one or more compounds selected from azomethine azo compounds and perylene compounds from the viewpoint of maintaining the light transmittance at a wavelength of 905 nm in a high range. That is, the design layer preferably contains one or more compounds selected from the azomethine azo compound and the perylene compound.

The content of one or more compounds selected from the azomethine azo compound and the perylene compound in the design layer varies depending on the thickness of the design layer, the composition of the core layer described above, and the like. The total solid content is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

The design layer may have a single-layer structure, but it is preferable to have a first unique design layer formed of halftone dots or meshes and a second design layer that is solid on the entire surface. With this configuration, the design property is imparted by the halftone dots or mesh of the first unique design layer, and the visible light concealment property is imparted by the solid printing on the entire surface of the second design layer, and the design property and the visible light concealment property are provided. Can be easily compatible with.
In particular, since both the first unique design layer and the second design layer contain one or more compounds selected from the azomethine azo compound and the perylene compound, the wavelength is achieved while achieving both design and visible light hiding. It is possible to easily maintain the light transmittance of 905 nm in a high range.

It is preferable that the halftone dots of the first unique craft layer have individual diameters of 5 to 100 μm and the distance between the centers of the halftone dots is 20 to 200 μm.
The mesh of the first unique design layer preferably has a line width of 20 to 100 μm and a distance between the centers of the lines of 20 to 200 μm.

The thickness of the design layer (when the design layer has the first unique design layer and the second design layer, the total thickness of the first unique design layer and the second design layer) is preferably 0.5 to 10 μm. It is more preferably about 7 μm, and even more preferably 3 to 5 μm.
When the design layer has the first unique design layer and the second design layer, the ratio of the thickness of the first unique design layer to the thickness of the second design layer is preferably 2: 8 to 8: 2. It is more preferably ~ 6: 4.

<Other layer 2 (layer located on the opposite side of the core layer from the antireflection layer)>
As described above, the design layer is preferably located on the opposite side of the core layer from the antireflection layer. A layer other than the design layer may be provided on the side of the core layer opposite to the antireflection layer. Further, on the side of the core layer opposite to the antireflection layer, a design layer may be provided but another layer may be provided (for example, FIGS. 2 and 5). Further, the core layer may not have a layer on the opposite side of the antireflection layer, and the core layer may be exposed (for example, FIG. 6).

Examples of the layer other than the design layer located on the opposite side of the core layer from the antireflection layer include a base material B, an adhesive layer B, a primer layer, and a hard coat layer B.

As shown in FIGS. 4 and 5, when the base material B (31) is provided on the side opposite to the antireflection layer of the core layer 10 (≈ the outer layer (30) has the base material B (31), but the base material B (31) is adhered. When the layer B (32) is not provided), it is preferable that the core layer (10) and the outer layer (30) are brought into close contact with each other by insert molding.
As shown in FIGS. 1 to 3, when the adhesive layer B (32) is provided on the side opposite to the antireflection layer of the core layer 10 (≈ the outer layer (30) is provided with the adhesive layer B (32), but the base. The core layer is formed by in-mold molding using a material B (31)) and a transfer sheet (a transfer sheet having a transfer layer (outer layer) including an adhesive layer B or the like on a release base material). It is preferable that (10) and the outer layer (30) are brought into close contact with each other, and then the release base material is peeled off.
Further, although not shown, when the adhesive layer B and the base material B are provided on the opposite side of the core layer from the antireflection layer (≈ when the adhesive layer B and the base material B are provided as the outer layer), the core layer is It is preferable to laminate the outer layer so that the core layer and the outer layer are in close contact with each other.

-Base material B-
Examples of the base material B include the plastic film exemplified in the base material A.
Among these plastic films, biaxially stretched polyester film is preferable from the viewpoint of heat resistance and dimensional stability, and acrylic film, polycarbonate film, or acrylic and polycarbonate from the viewpoint of moldability such as insert molding and weather resistance. A co-extruded film is preferred.

The thickness of the base material B is preferably 28 to 300 μm, more preferably 75 to 250 μm, from the viewpoints of moldability, handleability, and resistance to flying stones.

-Adhesive layer B-
The adhesive layer B may be a pressure-sensitive adhesive layer (so-called “adhesive layer”) or a heat-sensitive adhesive layer (so-called “heat seal layer”). When performing the above-mentioned lamination, a pressure-sensitive adhesive layer (adhesive layer) is preferable, and when performing the above-mentioned in-mold molding, a heat-sensitive adhesive layer (heat seal layer) is preferable.

Further, it is preferable to use a heat-sensitive or pressure-sensitive resin suitable for the material of the core layer for the adhesive layer B. The preferred embodiment of the adhesive layer B according to the material of the core layer is the same as the preferred embodiment of the adhesive layer A.

The thickness of the adhesive layer B is preferably 0.1 to 50 μm, more preferably 0.5 to 30 μm.

-Hard coat layer B-
The hard coat layer B is preferably arranged on the outermost surface of the layer located on the opposite side of the core layer from the antireflection layer. That is, the hard coat layer B is preferably arranged on the surface side of the outer layer (the side farthest from the core layer of the outer layer). By arranging the hard coat layer B at such a position, the scratch resistance of the resin panel can be improved, and the function of the infrared sensor can be easily maintained for a long period of time.

The hard coat layer B preferably contains a cured product of the curable resin composition as a main component.
The main component means 50% by mass or more of the total solid content constituting the hard coat layer B, preferably 70% by mass or more, and more preferably 80% by mass or more.

Examples of the curable resin composition of the hard coat layer B include a thermosetting resin composition and an ionizing radiation curable resin composition, and an ionizing radiation curable resin composition is preferable.
Examples of the thermosetting resin composition and the ionizing radiation curable resin composition of the hard coat layer B include the same as the thermosetting resin composition and the ionizing radiation curable resin composition of the low refractive index layer.

The hard coat layer B may contain inorganic particles in order to increase the hardness.
The embodiment of the inorganic particles of the hard coat layer B (particle type, average particle size, content) is the same as that of the inorganic particles of the hard coat layer A.

Since the hard coat layer B is located on the outside, it is preferable to contain a weather resistant agent.
Examples of the weather resistant agent include general-purpose ultraviolet absorbers and light stabilizers. The content of the weathering agent is preferably 0.1 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the cured product of the curable resin composition.

The thickness of the hard coat layer B is preferably 1 to 20 μm, more preferably 2 to 10 μm, and even more preferably 3 to 5 μm.

-Primer layer-
The primer layer is a layer arranged between the layers as needed in order to enhance the interlayer adhesion. The position of the primer layer is not particularly limited, and for example, it can be arranged between the hard coat layer B and the design layer.

The primer layer preferably contains a resin component as a main component.
Examples of the resin component of the primer layer include a cured product of a thermoplastic resin and a curable resin composition, and a cured product of the curable resin composition is preferable, and a cured product of the thermosetting resin composition is more preferable.
Examples of the thermosetting resin composition used as the resin component of the primer include the same thermosetting resin compositions exemplified in the low refractive index layer.

The thickness of the primer layer is preferably 1 to 20 μm, more preferably 2 to 10 μm, and even more preferably 3 to 5 μm.

-ATO (antimony tin oxide), ITO (tin indium oxide)-
The resin panel of the present invention may contain one or more infrared absorbers selected from ATO and ITO in any of the outer layers.
ATO and ITO have a property of transmitting most of the near infrared rays having a wavelength of more than 905 nm while transmitting light having a wavelength of 905 nm at a predetermined ratio. Therefore, by including one or more infrared absorbers selected from ATO and ITO in any of the outer layers, the light transmittance at a wavelength of 905 nm is maintained at a high level, while near infrared rays having a wavelength exceeding 905 nm are maintained. By cutting the infrared sensor, it is possible to suppress the temperature rise inside the infrared sensor and make it easier to fully demonstrate the function of the infrared sensor.

It is preferable that one or more infrared absorbers selected from ATO and ITO are contained in any one or more layers selected from the adhesive layer B, the hard coat layer B, and the primer layer.
The content of one or more infrared absorbers selected from ATO and ITO may be appropriately adjusted within a range in which the light transmittance of the resin panel at a wavelength of 905 nm can be maintained at 85% or more.
When tungsten cesium oxide and lanthanum hexaboride, which are typical examples of infrared absorbers, are used, it is difficult to maintain a high level of light transmittance at a wavelength of 905 nm.

[Manufacturing method of resin panel]
The resin panel of the present invention can be manufactured, for example, by laminating, insert molding, in-mold molding, or the like.
Hereinafter, examples of manufacturing the resin panels of FIGS. 1 to 6 will be described.

<Manufacturing example of the resin panel shown in FIG. 1>
The resin panel of FIG. 1 can be manufactured, for example, by a process including the following 1-1 to 1-5.

1-1. A step of preparing a laminate film for forming an inner layer (20) having an adhesive layer A (21), a base material A (22), a hard coat layer A (24), and an antireflection layer (23) in this order.
1-2. Transfer for in-mold molding for forming the outer layer (30), which has the release base material B (not shown), the hard coat layer B (35), the design layer (33), and the adhesive layer B (32) in this order. The process of preparing sheet B.
1-3. The transfer sheet B of 1-2 is arranged in the in-mold molding mold (the transfer sheet B is arranged in the mold so that the adhesive layer B (32) faces the inside of the mold). A step of injecting a core layer forming composition by injection to obtain a laminate in which the core layer (10) and the adhesive layer B (32) of the transfer sheet B are in close contact with each other.
1-4. A step of peeling the release base material B from the laminate obtained in 1-3 above.
1-5. On the surface side where the core layer (10) of the laminate obtained in 1-3 or the release base material B of 1-4 is peeled off, the adhesive layer A of the laminate film of 1-1 is exposed. 21) The process of pasting the sides together.

<Manufacturing example of the resin panel shown in FIG. 2>
The resin panel of FIG. 2 can be manufactured, for example, by a process including the following 2-1 to 2-5.

2-1. A step of preparing an insert molding film A for forming an inner layer (20), which has a base material A (22), a hard coat layer A (24), and an antireflection layer (23) in this order.
2-2. A step of preparing a transfer sheet B for in-mold molding for forming an outer layer (30), which has a release base material B (not shown), a hard coat layer B (35), and an adhesive layer B (32) in this order. ..
2-3. A step of arranging the insert molding film A of 2-1 in the vacuum forming mold, vacuum forming (offline preforming), and trimming an excess portion as necessary to obtain a forming sheet A.
2-4. The molding sheet A obtained in 2-3 above is placed on one side of a pair of injection molding (insert and in-mold batch molding) dies, and 2-2 above is placed on the other side of the dies. The transfer sheet B is arranged, and then the core layer forming composition is injection-injected into the base material A (22) of the molded sheet A, the core layer (10), and the adhesive layer B (32) of the transfer sheet B. The process of obtaining a laminated body in which the above is closely adhered.
2-5. A step of peeling the release base material B from the laminate obtained in 2-4 above.

<Manufacturing example of the resin panel shown in FIG. 3>
The resin panel of FIG. 3 can be manufactured, for example, by a process including the following 3-1 to 3-4.

3-1. For in-mold molding for forming the inner layer (20), which has the release base material A (not shown), the antireflection layer (23), the hard coat layer A (24), and the adhesive layer A (21) in this order. A step of preparing the transfer sheet A.
3-2. Transfer for in-mold molding for forming the outer layer (30), which has the release base material B (not shown), the hard coat layer B (35), the design layer (33), and the adhesive layer B (32) in this order. The process of preparing sheet B.
3-3. The transfer sheet A of 3-1 is arranged on one side of the pair of in-mold molding dies, and the transfer sheet B of 3-2 is arranged on the other side of the mold (transfer sheet). A and the transfer sheet B are arranged in the mold so that the adhesive layer A (21) and the adhesive layer B (32) face the inside of the mold, respectively, and the adhesive layer A and the adhesive layer B face each other.) After that, the composition for forming the core layer is injection-injected, and the adhesive layer A (21) of the transfer sheet A, the core layer (10), and the adhesive layer B (32) of the transfer sheet B are brought into close contact with each other. The process of obtaining.
3-4. A step of opening the mold and peeling the release base material A and the release base material B from the laminate obtained in 3-3.

<Manufacturing example of the resin panel in FIG. 4>
The resin panel of FIG. 4 can be manufactured, for example, by a process including the following 4-1 to 4-5.

4-1. A step of preparing a laminate film for forming an inner layer (20), which has an adhesive layer A (21), a base material A (22), and an antireflection layer (23) in this order.
4-2. A step of preparing an insert molding film for forming an outer layer (30), which has a base material B (31), a design layer (33), a primer layer (34), and a hard coat layer B (35) in this order.
4-3. A step of arranging the above-mentioned 4-2 insert molding film in a vacuum forming mold, vacuum forming (offline preforming), and trimming an excess portion as necessary to obtain a molded sheet.
4-4. The molding sheet obtained in 4-3 above is inserted into an injection molding die, the composition for forming a core layer is injection-injected, and a laminate in which the core layer (10) and the molding sheet (outer layer) are in close contact with each other is formed. The process of obtaining.
4-5. A step of bonding the adhesive layer A (21) side of the laminate film of 4-1 to the exposed surface side of the core layer of the laminate obtained in 4-4.

<Manufacturing example of the resin panel shown in FIG. 5>
The resin panel of FIG. 5 can be manufactured, for example, by a process including the following 5-1 to 5-5.

5-1. A step of preparing an insert molding film A for forming an inner layer (20), which has a base material A (22), a hard coat layer A (24), and an antireflection layer (23) in this order.
5-2. A step of preparing an insert molding film B for forming an outer layer (30), which has a base material B (31), a primer layer (34), and a hard coat layer B (35) in this order.
5-3. A step of arranging the insert molding film A of 5-1 above in a vacuum forming mold, vacuum forming (offline preforming), and trimming an excess portion as necessary to obtain a forming sheet A.
5-4. A step of arranging the insert molding film B of 5-2 in a vacuum forming mold, vacuum forming (offline preforming), and trimming an excess portion as necessary to obtain a forming sheet B.
5-5. The molding sheet A obtained in 5-3 above was placed on one side of the pair of insert molding dies, and the molding sheet B obtained in 5-4 above was placed on the other side of the mold. After that, the composition for forming the core layer is injected and injected to obtain a laminate in which the molding sheet A (inner layer), the core layer (10), and the molding sheet B (outer layer) are in close contact with each other.

<Manufacturing example of the resin panel in FIG. 6>
The resin panel of FIG. 6 can be manufactured, for example, by a process including the following 6-1 to 6-3.

6-1. A step of preparing a laminate film for forming an inner layer (20), which has an adhesive layer A (21), a base material A (22), and an antireflection layer (23) in this order.
6-2. A step of preparing a molded core layer (10).
6-3. A step of adhering the adhesive layer A (21) side of the laminate film of 6-1 to the core layer.

[Infrared sensor]
The infrared sensor of the present invention includes an infrared light emitting element, an infrared light receiving element, and a protective cover arranged in front of the infrared light emitting element and the infrared light receiving element, and the protective cover is the above-described invention of the present invention. It is a resin panel of.

The infrared light emitting element can be used without particular limitation as long as it emits an infrared laser. The wavelength of the infrared laser is preferably 905 nm.
Further, the infrared light receiving element can be used without particular limitation as long as it can receive the infrared laser.
The infrared light emitting element and the infrared light receiving element are preferably arranged in the housing.

It is preferable that the housing has a window portion and can irradiate and receive infrared rays through the window portion. Further, it is preferable to install a protective cover on the window portion.

The protective cover is arranged in front of the infrared light emitting element and the infrared light receiving element. The infrared sensor of the present invention needs to use the resin panel of the present invention described above as a protective cover.
By using the resin panel of the present invention described above as the protective cover, the infrared sensor is less likely to malfunction, and the infrared sensor can function sufficiently.
When the resin panel has an antireflection layer, it is preferable to arrange the resin panel so that the side having the antireflection layer faces the infrared light emitting element and the infrared light receiving element side.

The infrared sensor is useful as a distance sensor (LiDAR) and can be used, for example, as a sensor for driving a car.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the embodiments described in the examples.

1. 1. Measurement and Evaluation The following measurements and evaluations were performed on the resin panels obtained in Examples and Comparative Examples. The results are shown in Table 1.

1-1. Transmittance The light transmittance (infrared transmittance) at a wavelength of 905 nm and the visible light transmittance of the resin panel were measured using an ultraviolet-visible spectrophotometer equipped with the following functions and specifications. Regarding Examples 1 to 4 and Comparative Example 3, the measurement was performed both when the inner surface (the surface having the antireflection layer) was the light incident surface and when the outer surface was the light incident surface. Carried out.

<Functions and specifications>
-Model: Ultraviolet-visible spectrophotometer manufactured by JASCO Corporation (model number: V-670)
-Attached unit: Integrating sphere unit (manufactured by JASCO Corporation, product number: ISN-723)
-Light source: Deuterium lamp (190-350 nm), halogen lamp (330-2700 nm)
-Measurement wavelength interval; 1 nm
・ Measurement spot diameter: 2 to 20 mm

1-2. Scratch resistance The outer surface of the resin panels of Examples 1 to 4 and Comparative Example 3 (the surface opposite to the side having the antireflection layer) and the core layer of the resin panels of Comparative Examples 1 and 2 are exposed. Steel wool (“Bonster # 0000”, manufactured by Nippon Steel Wool Co., Ltd.) was reciprocated 100 times with a load of 100 g / m ^{2 with respect to the surface, and the surface condition was visually observed.} There were no scratches and the level was such that no change in gloss was confirmed, 3 points, slight scratches, and 2 points where slight changes in gloss were confirmed, scratches were confirmed, and significant gloss. Twenty subjects evaluated the results with one point being the one in which the change was confirmed. The average score of the evaluation of 20 people was calculated and ranked according to the following criteria.
<Scratch resistance evaluation criteria>
A: Average score is 2.5 or more B: Average score is 2.0 or more and less than 2.5 C: Average score is less than 2.0

2. Preparation of coating liquid The following coating liquid was prepared. In addition, "part" and "%" are based on mass.

<Coating liquid for hard coat layer 1>
-Urethane acrylate-based UV curable resin composition 100 parts (solid content 35%, toluene / ethyl acetate mixed solvent)
-Photopolymerization initiator 1.5 parts (IGM Resins BV, trade name "Omnirad 184")

<Coating liquid 2 for hard coat layer (electron beam curing type)>
-Urethane acrylate-based UV curable resin composition 100 parts (solid content 35%, toluene / ethyl acetate mixed solvent)
・ 5 parts of silica particles (average particle size: 3 μm)
-Weather resistant 3 parts (manufactured by BASF, product number: Tinuvin479)

<Laminated body 1 for forming an adhesive layer (adhesive layer)>
-A laminate (manufactured by Panac Co., Ltd., trade name: Panaclean PD-S1) having separators on both sides of a transparent adhesive layer having a thickness of 25 μm was prepared.

<Coating liquid 2 for adhesive layer (heat seal layer)>
・ 100 parts of acrylic resin (trade name “TM-R600 (NT) K3”, manufactured by Dainichiseika Kogyo Co., Ltd., solid content 20%)
・ Diluting solvent Appropriate amount (methyl ethyl ketone, toluene)

<Coating liquid for low refractive index layer 1>
-Ultraviolet curable compound 1.0 part (3-4 functional alkoxylated pentaerythritol acrylate, manufactured by Nippon Kayaku Co., Ltd., trade name "PET-30")
-Photopolymerization initiator 0.07 part (IGM Resins BV, trade name "Omnirad 127")
-Hollow silica 1.1 parts (average particle size 60 nm)
・ Fluorine-based antifouling agent 0.1 parts (active ingredient: 0.005 parts by mass)
(Product name "X-71-1203M" manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Appropriate amount of diluting solvent

<Coating liquid 1 for design layer (common to the first unique design layer and the second design layer)>
・ Binder resin 100 parts by mass (acrylic urethane resin)
20 parts by mass of azomethine azo compound (black pigment, manufactured by Dainichiseika Kogyo, trade name: Chromofine Black A1103)
・ Appropriate amount of diluting solvent

<Coating liquid 2 for design layer (common to the first unique design layer and the second design layer)>
・ Binder resin 100 parts by mass (acrylic urethane resin)
40 parts by mass of azomethine azo compound (black pigment, manufactured by Dainichiseika Kogyo, trade name: Chromofine Black A1103)
・ Appropriate amount of diluting solvent

<Coating liquid for primer layer 1>
・ 100 parts of acrylic polyol (manufactured by Dainichiseika Kogyo Co., Ltd., product name: TM-VMAC)
-Isocyanate compound 1 part (manufactured by Dainichiseika Kogyo Co., Ltd., trade name: RC-3 curing agent)
・ Appropriate amount of diluting solvent

3. 3. Preparation of molding material 3-1. Laminate film A hard coat layer A was formed by applying, drying, and irradiating ultraviolet rays on a polyethylene terephthalate film having a thickness of 50 μm so that the thickness of the hard coat coating liquid 1 after drying was 4 μm. Next, the coating liquid 1 for the low refractive index layer 1 is coated, dried, and irradiated with ultraviolet rays on the hard coat layer A so that the thickness after drying is 175 nm to form a single antireflection layer of the low refractive index layer. Formed. Next, one separator of the laminated body 1 is peeled off and bonded to the surface of the polyethylene terephthalate film opposite to the hard coat layer, and then the other separator of the laminated body 1 is peeled off to form an adhesive layer A (adhesive layer). ), The base material A (polyethylene terephthalate film), the hard coat layer A, and the antireflection layer (single layer of the low refractive index layer) in this order.
The refractive index of the low refractive index layer coating liquid 1 to the low refractive index layer was 1.36.

3-2. Insert molding film A polyethylene terephthalate film having a thickness of 50 μm was changed to an acrylic film having a thickness of 125 μm, and an insert molding film was obtained in the same manner as in 3-1 except that an adhesive layer A (adhesive layer) was not formed. .. The insert molding film has a base material A (acrylic film), a hard coat layer A, and an antireflection layer (a single layer of a low refractive index layer) in this order.

3-3. Transfer sheet for in-mold molding 1
On a polyethylene terephthalate film (release base material A) having a releasability of 50 μm, the coating liquid 1 for a low refractive index layer was applied, dried, and irradiated with ultraviolet rays so that the thickness after drying was 175 nm. A single antireflection layer of a low refractive index layer was formed. Next, the hard coat layer A was formed by applying, drying, and irradiating ultraviolet rays on the low refractive index layer so that the thickness of the hard coat coating liquid 1 after drying was 4 μm. Next, the coating liquid 2 for the adhesive layer (heat seal layer) is applied and dried on the hard coat layer A so that the thickness after drying is 2 μm to form an adhesive layer A having a heat seal property. A transfer sheet 1 for in-mold molding was obtained.
The transfer sheet 1 has a release base material A, an antireflection layer (single layer of a low refractive index layer), a hard coat layer A, and an adhesive layer A (heat seal layer) in this order.

3-4. Transfer sheet for in-mold molding 2
On a polyethylene terephthalate film (release base material B) having a releasability of 50 μm, the hard coat coating liquid 2 is applied, dried, and irradiated with an electron beam so that the thickness after drying becomes 4 μm, and then hardened. A coat layer B was formed. Next, the coating liquid 1 for the design layer was applied onto the hard coat layer B in a halftone dot shape (halftone dot diameter: 30 μm, distance between the centers of the halftone dots: 70 μm) and dried to obtain a second unique craft layer having a thickness of 2 μm. Formed. Next, the coating liquid 1 for the design layer was applied solidly on the first unique design layer and dried to form a second design layer having a thickness of 2 μm. Next, the coating liquid 2 for the adhesive layer (heat seal layer) is applied and dried on the second design layer so that the thickness after drying is 2 μm to form an adhesive layer B having a heat seal property. A transfer sheet 2 for in-mold molding was obtained.
The transfer sheet 2 has a release base material B, a hard coat layer B, a design layer, and an adhesive layer B (heat seal layer) in this order.

3-5. Transfer sheet for in-mold molding 3
A transfer sheet 3 for in-mold molding was obtained in the same manner as in 3-4 except that the design layer was not formed. The transfer sheet 3 has a release base material B, a hard coat layer B, and an adhesive layer B (heat seal layer) in this order.

3-6. Transfer sheet for in-mold molding 4
In-mold in the same manner as 3-4, except that the coating liquid 1 for the design layer was changed to the coating liquid 2 for the design layer, and the thicknesses of the first unique design layer and the second design layer were changed from 2 μm to 3 μm. A transfer sheet 4 for molding was obtained. The transfer sheet 4 has a release base material B, a hard coat layer B, a design layer, and an adhesive layer B (heat seal layer) in this order.

4. Fabrication of Resin Panel [Example 1]
The transfer sheet 2 of 3-4 was arranged in the in-mold molding mold (the transfer sheet 2 was arranged in the mold so that the adhesive layer B faces the inside of the mold).
Next, the mold is closed, and a composition for forming a core layer in the mold (a composition containing 30 parts by mass of an azomethine azo compound with respect to 100 parts by mass of a polycarbonate resin. Trade name "Makrolon AX2675ST" manufactured by Covestro, color number : 978001 ") was injected and injected to obtain a laminate in which the core layer (thickness 4.0 mm) and the adhesive layer B side of the transfer sheet 2 were in close contact with each other.
Next, the release base material B was peeled off from the laminate.
Next, the adhesive layer A side of the laminate film of 3-1 was bonded to the exposed surface side of the core layer of the laminate to obtain the resin panel of Example 1. The resin panel of Example 1 has the layer structure shown in FIG.

[Example 2]
The insert molding film of 2-1 was placed in the vacuum forming mold, vacuum formed (offline preforming), and the excess portion was trimmed to obtain a molded sheet 1.
Next, the molding sheet 1 is arranged on one side of a pair of injection molding (insert and in-mold batch molding) molds, and the transfer sheet 3 of 3-5 is placed on the other side of the mold. (The transfer sheet 3 was arranged in the mold so that the adhesive layer B faces the inside of the mold).
Next, the mold is closed, and a composition for forming a core layer in the mold (a composition containing 30 parts by mass of an azomethine azo compound with respect to 100 parts by mass of a polycarbonate resin. Trade name "Makrolon AX2675ST, color number" manufactured by Covestro Co., Ltd. : 978001 ") was injected and injected to obtain a laminate in which the adhesive layer A of the molded sheet 1, the core layer (thickness 4.0 mm), and the adhesive layer B of the transfer sheet 3 were in close contact with each other.
Next, the release base material B was peeled off from the laminate to obtain a resin panel of Example 2. The resin panel of Example 2 has the layer structure shown in FIG.

[Example 3]
The transfer sheet 1 of 3-3 was arranged on one side of a pair of upper and lower in-mold molding dies, and the transfer sheet 4 of 3-6 was arranged on the other side of the mold (transfer). The sheet 1 and the transfer sheet 4 are arranged in the mold so that the adhesive layer A and the adhesive layer B face the inside of the mold, respectively, and the adhesive layer A and the adhesive layer B face each other.)
Next, the mold is closed, and the composition for forming the core layer (transparent polycarbonate resin) is injected into the mold to form the adhesive layer A of the transfer sheet 1 and the core layer (transparent core layer, thickness 4.0 mm). , A laminated body in which the adhesive layer B of the transfer sheet 4 was in close contact was obtained.
Next, the release base material A and the release base material B were peeled off from the laminate to obtain a resin panel of Example 3. The resin panel of Example 3 has the layer structure shown in FIG.

[Example 4]
A composition containing 30 parts by mass of an azomethine azo compound (trade name "Makrolon AX2675ST, color number: 978001" manufactured by Covestro Co., Ltd.) with respect to 100 parts by mass of a polycarbonate resin is formed into a plate having a thickness of 4.0 mm. The core layer was prepared.
The adhesive layer A side of the laminate film of 3-1 was bonded to the core layer to obtain a resin panel of Example 4. The resin panel of Example 4 has the layer structure shown in FIG.

[Comparative Example 1]
As the resin panel of Comparative Example 1, a composition containing 30 parts by mass of an azomethine azo compound (trade name "Makrolon AX2675ST, color number: 978001" manufactured by Covestro Co., Ltd.) with respect to 100 parts by mass of a polycarbonate resin was applied with a thickness of 4.0 mm. A plate-shaped product was prepared.

[Comparative Example 2]
As the resin panel of Comparative Example 2, a transparent polycarbonate resin plate having a thickness of 4.0 mm was prepared.

[Comparative Example 3]
A resin panel of Comparative Example 3 was obtained in the same manner as in Example 2 except that the azomethine azo compound was removed from the composition for forming the core layer. The resin panel of Comparative Example 3 is the same as the resin panel of Example 2 except that the core layer does not contain an azomethine azo compound and is transparent.

As is clear from Table 1, the resin panel of the example can maintain the infrared transmittance at a high level while suppressing the visible light transmittance at a low level, and when applied as a protective cover for an infrared sensor. In addition, it can be confirmed that the infrared sensor can function sufficiently.

10: Core layer 20: Inner layer 21: Adhesive layer A
22: Base material A
23: Antireflection layer 24: Hard coat layer A
30: Outer layer 31: Base material B
32: Adhesive layer B
33: Design layer 33A: First unique design layer 33B: Second design layer 34: Primer layer 35: Hard coat layer B
100: Resin panel

Claims (10)

A resin panel having at least a core layer, wherein the resin panel has a light transmittance of 85% or more and a visible light transmittance of 20% or less at a wavelength of 905 nm. The resin panel according to claim 1, wherein the core layer contains a polycarbonate resin. The resin panel according to claim 1 or 2, wherein the core layer contains one or more compounds selected from an azomethine azo compound and a perylene compound. The resin panel according to any one of claims 1 to 3, wherein an antireflection layer is arranged on the surface of at least one side. The resin according to claim 4, wherein the antireflection layer has a low refractive index layer on the surface side, and the low refractive index layer has a refractive index of 1.28 to 1.40 and a thickness of 120 to 250 nm. panel. The resin panel according to any one of claims 1 to 5, wherein the resin panel has a design layer. The resin panel according to claim 6, wherein the design layer, the core layer, and the antireflection layer are provided in this order, and the antireflection layer is arranged on the surface of the resin panel. The resin panel according to claim 6 or 7, wherein the design layer has a first unique design layer formed of halftone dots or mesh and a second design layer that is solid on the entire surface. The resin panel according to any one of claims 6 to 8, wherein the design layer contains one or more compounds selected from an azomethine azo compound and a perylene compound. An infrared sensor having an infrared light emitting element, an infrared light receiving element, and a protective cover arranged in front of the infrared light emitting element and the infrared light receiving element, wherein the protective cover is any of claims 1 to 9. The infrared sensor, which is the described resin panel.

Images