Film, optical module, transfer film, and method for manufacturing molded body

Abstract

This film has a stress relaxation rate of 70% or more, as calculated by Equation 1. [Method for measuring stress relaxation rate] The film is cut into a strip-shaped test piece measuring 10 mm in length and 30 mm in width, with at least one direction of the film defined as the length direction. This strip-shaped test piece is stretched in the length direction using a tension tester at a tensile speed of 200 mm / min in an environment of a temperature of 25°C and a relative humidity of 45%, and elongation is stopped when an elongation rate of 50% is reached. The stress value of the film is continuously measured from the start of stretching to 30 seconds after the stop of elongation. The stress relaxation rate (%) of the film is calculated on the basis of Expression 1 where "A" (N) is the stress value showing the highest stress within the measurement time, and "B" (N) is the stress value at 30 seconds after the stop of elongation. Expression 1: Stress relaxation rate (%) = (A-B) / A×100

Description

Film, optical module, transfer film, and method for manufacturing molded article

[0001] The present invention relates to a film, an optical module, a transfer film, and a method for producing a molded article.

[0002] Sensor technology and communication technology using near-infrared rays have been developed or put into practical use. Because elements that receive near-infrared rays are also sensitive to visible light, near-infrared transmission filters that selectively transmit only near-infrared rays are used.

[0003] Conventional near-infrared transmission filters have mainly been black in color because they absorb visible light. Therefore, conventional near-infrared transmission filters have a problem of poor designability. Therefore, for example, Patent Document 1 discloses an optical filter that can realize an infrared transmission filter with a high linear transmittance of infrared light and that is generally white in color.

[0004] Furthermore, in order to be used in applications where the laminate is bent during use, the laminate has good bending resistance and includes a laminate film including a substrate and an inorganic layer having a thickness of 50 μm or less, and a resin layer provided directly on the laminate film, and the resin layer has a tensile modulus of elasticity of 10 １ Pa or more 10 ９ A laminate has been proposed in which the tensile modulus of elasticity of the laminate film is less than Pa and the tensile modulus of elasticity of the laminate film is 5% or more higher than the tensile modulus of the substrate (see Patent Document 2).

[0005] JP 2022-69678 A JP 2020-131476 A

[0006] In order to accommodate various shapes, there is a demand for improved three-dimensional formability of films that can be applied to optical filters.

[0007] The optical filter described in Patent Document 1 has a problem in that it breaks when bent and cannot be molded. In addition, the optical filter described in Patent Document 2 is a film produced by hot melt extrusion that has good bending resistance and does not deform even when bent, and is therefore unsuitable for three-dimensional molding.

[0008] An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a film that is excellent in three-dimensional formability.

[0009] In one embodiment of the present invention, the film is characterized by having a stress relaxation rate of 70% or more as calculated by the following formula 1. [Method for Measuring Stress Relaxation Rate] At least one direction of the film is set as the length direction, and a strip-shaped test specimen of 10 mm length x 30 mm width is cut out. This strip-shaped test specimen is stretched in the length direction at a tension speed of 200 mm / min using a tensile tester under an environment of 25°C temperature and 45% relative humidity, and is stretched to an elongation rate of 50% and then stopped. The stress value of the film is continuously measured from the start of stretching until 30 seconds after the stretching has stopped. The stress value that exhibits the highest stress within that measurement time is designated as "A" (N), and the stress value 30 seconds after the stretching has stopped is designated as "B" (N), and the stress relaxation rate (%) of the film is calculated based on the following formula 1. [Formula 1] Stress relaxation rate (%) = (A - B) / A x 100

[0010] The embodiments of the present invention can provide a film that has excellent three-dimensional formability.

[0011] Fig. 1 is a schematic diagram illustrating the optical properties of a film according to an embodiment of the present invention. Fig. 2 is a schematic diagram illustrating a method for measuring the linear transmittance of a film according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view illustrating an example of a film according to an embodiment of the present invention. Fig. 4 is a graph showing the progress of stress from the start of tension (0 seconds) to 50 seconds after tension measurement was performed on the films of Examples 1 to 3 and Comparative Examples 1 and 2. The vertical axis represents stress (MPa), and the horizontal axis represents time (seconds).

[0012] Hereinafter, embodiments of the present invention will be described in detail. Note that the embodiments are not limited by the following description and can be modified as appropriate within the scope of the present invention. Furthermore, in this specification, unless otherwise specified, the term "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0013] Furthermore, when describing embodiments of the present invention with reference to the drawings, the same components in each drawing may be designated by the same reference numerals, and duplicated explanations may be omitted. Furthermore, the number, position, size, shape, etc. of components are not limited to the embodiments of the present invention, and may be any number, position, size, shape, etc. that is preferable for implementing the present invention.

[0014] (Film) A film according to an embodiment of the present invention has a stress relaxation rate of 70% or more, as calculated by the following formula 1. -Method for measuring stress relaxation rate- At least one direction of the film is set as the length direction, and a strip-shaped test piece of 10 mm length x 30 mm width is cut out. This strip-shaped test piece is pulled in the length direction at a pulling rate of 200 mm / min using a tensile tester under an environment of a temperature of 25°C and a relative humidity of 45%, and is stretched to an elongation rate of 50% and then stopped. The stress value of the film is continuously measured from the start of pulling until 30 seconds after the stretching has stopped. The stress value that shows the highest stress within that measurement time is then designated as "A" (N), and the stress value 30 seconds after the stretching has stopped is designated as "B" (N), and the stress relaxation rate (%) of the film is calculated based on the following formula 1. [Formula 1] Stress relaxation rate (%) = (A - B) / A x 100

[0015] In this specification, a layer having a stress relaxation rate of 70% or more calculated by the above formula 1 may be referred to as a "first layer." The film according to the embodiment of the present invention may have a single-layer structure consisting of only the first layer, a laminate structure of the first layer and other layers, or a laminate structure having multiple first layers and multiple other layers. When the film according to the embodiment of the present invention has a laminate structure, the lamination order is not particularly limited as long as it does not impair the effects of the present invention, and can be appropriately selected depending on the purpose. Among these, the film according to the embodiment of the present invention preferably has a single-layer structure consisting of only the first layer.

[0016] [Stress Relaxation Rate] The stress relaxation rate of the first layer of the film according to an embodiment of the present invention is 70% or more, preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more. A stress relaxation rate of the first layer of 70% or more provides excellent three-dimensional (3D) formability. The upper limit of the stress relaxation rate of the first layer is not particularly limited, and a higher value is preferable because it provides better three-dimensional formability. In an embodiment of the present invention, the stress relaxation rate of the first layer is determined by the stress relaxation rate calculation method described above.

[0017] The stress value A of the first layer of the film is not particularly limited as long as the stress relaxation rate of the first layer is 70% or more, but is preferably 5 MPa or less, more preferably 4 MPa or less, and even more preferably 3 MPa or less. The lower limit of the stress value A is 0 MPa, and a lower value is preferable because the residual stress is smaller and deformation of the film after molding is less likely to occur.

[0018] The stress value B of the film is not particularly limited as long as the stress relaxation rate of the first layer is 70% or more, but the upper limit of the stress value B is preferably 3 MPa or less, more preferably 2 MPa or less, and even more preferably 1 MPa or less.

[0019] The direction in which the stress relaxation rate of the first layer is 70% or more is the same as the direction in which the stress value B is in the preferred range. Although it depends on the method for forming the first layer in the production of the film, when the first layer is formed by a coating method, a printing method, or the like, a uniform film can be formed, and therefore, the "at least one direction" is not particularly limited.

[0020] The difference (A-B) between the stress value A and the stress value B is not particularly limited, but is preferably 3 MPa or less, more preferably 2 MPa or less, and even more preferably 1 MPa or less.

[0021] When the film according to the embodiment of the present invention has layers other than the first layer, the other layers can be selected so as not to affect the stress relaxation rate of the first layer.

[0022] [Young's Modulus] The Young's modulus of the first layer of the film according to an embodiment of the present invention is not particularly limited, but is preferably 0.03 MPa or less, more preferably 0.02 MPa or less, and even more preferably 0.01 MPa or less. When the Young's modulus of the first layer of the film is within the above-mentioned preferred range, the film has better three-dimensional formability. The lower limit of the Young's modulus of the first layer of the film is 0 MPa, and the lower the Young's modulus, the easier it is to deform, resulting in better 3D formability of the film. The Young's modulus is calculated using the following Young's modulus calculation method.

[0023] -Method of calculating Young's modulus- A strip-shaped test specimen measuring 10 mm in length and 30 mm in width is obtained by cutting at least one direction as the length direction from the first layer of the film. This strip-shaped test specimen is pulled in the length direction at a pulling rate of 1 mm / min using a tensile tester in an environment of 25°C temperature and 45% relative humidity, stretched (elongated) to an elongation of 10%, and then allowed to stand for 5 minutes. The strain when allowed to stand for 5 minutes from the application of the preliminary force is taken as ε1, and the stress value is taken as "C" (N). After allowing to stand for 5 minutes, the test specimen is further pulled in the length direction at 100 mm / min, stretched (elongated) to an elongation of 10%, and then stopped. The strain at the time of stopping is taken as ε2, and the stress value is taken as "D" (N). Young's modulus (MPa) is calculated based on the following formula 2. [Equation 2] Young's modulus (MPa)=(stress D−stress C) / (strain ε2−strain ε1) In Equation 2, the strain ε1 is set to 0.5% and the strain ε1 is set to 2%.

[0024] When the film according to the embodiment of the present invention has layers other than the first layer, the other layers can be selected so as not to affect the Young's modulus of the film.

[0025] [Three-dimensional formability] The film according to an embodiment of the present invention has excellent three-dimensional formability. In an embodiment of the present invention, "three-dimensional formability" means the property of being able to be formed into a three-dimensional shape having depth in addition to height and width. In an embodiment of the present invention, the three-dimensional formability can be confirmed by the following method.

[0026] A film according to an embodiment of the present invention is heated to 100°C using a hot plate, and a mold (sealing stamp head wax seal stamp sealing wax (Tulip, regular series), manufactured by WXVOVXW) is pressed against it to obtain a molded product with a three-dimensional structure. The temperature is then lowered to 40°C, and if the desired three-dimensional shape can be produced, it is determined to have three-dimensional formability.

[0027] [Whiteness] The film according to the embodiment of the present invention may exhibit a white color. In the embodiment of the present invention, "whiteness" means the degree of whiteness. In the embodiment of the present invention, the whiteness is measured by a spectrophotometer using the SCE method in the CIE 1976 color space with the D65 light source as the standard light source, and is expressed as the L ＊ It can be evaluated by the value of

[0028] L of the film according to an embodiment of the present invention ＊ The value of L is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60 or more, more preferably 70 or more, and even more preferably 75 or more. ＊ The larger the value of L, the higher the whiteness. ＊ If the value of L is 60 or more, it can be said that the film is generally white. ＊ The upper limit of the value is 100.

[0029] When the film according to the embodiment of the present invention has layers other than the first layer, the other layers can be selected so as not to affect the whiteness of the first layer.

[0030] [In-Line Transmittance] The in-line transmittance of the film according to the embodiment of the present invention to near-infrared light is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40% or more, more preferably 50% or more, even more preferably 65% ​​or more, and particularly preferably 70% or more. When the in-line transmittance of the film to near-infrared light is 40% or more, the first layer can also function as a near-infrared transmitting layer. The near-infrared transmitting layer refers to a filter layer having spectral characteristics that block at least a portion of visible light and transmit at least a portion of near-infrared light.

[0031] The definition of near-infrared light varies depending on the technical field, but in an embodiment of the present invention, "near-infrared light" refers to light that includes at least light (electromagnetic waves) having a wavelength in the range of 760 nm to 2,000 nm. This wavelength range is suitable for use in sensing or communication. Furthermore, in an embodiment of the present invention, "visible light" refers to light having a wavelength in the range of 400 nm to less than 760 nm.

[0032] The wavelength range of light in which the film according to an embodiment of the present invention has a linear transmittance of 40% or more for near-infrared light is not particularly limited as long as it is near-infrared light, and can be appropriately selected depending on the purpose. However, the wavelength range is preferably 810 nm or more and 1,700 nm or less, more preferably 840 nm or more and 1,650 nm or less, even more preferably 840 nm or more and 1,000 nm or less, and particularly preferably 840 nm or more and 950 nm or less.

[0033] When the film according to the embodiment of the present invention has an in-line transmittance of 40% or more for light with a wavelength of 810 nm or more and 1,700 nm or less, it can be suitably used in, for example, InGaAs sensors, InGaAs / GaAsSb sensors, CMOS sensors, NMOS sensors, CCD sensors, etc.

[0034] In addition, when the film according to the embodiment of the present invention has layers other than the first layer, the other layers can be selected so as not to affect the linear transmittance of the first layer for near-infrared rays.

[0035] Next, the optical properties of the film according to the embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram for explaining an example of the optical properties of the film according to the embodiment of the present invention. When incident light I ０ When incident light I ０ A portion of the transmitted light I ｉ ), and a part of it is reflected at the interface (interface reflected light R ｉ ), and the other part is preferably scattered. The scattered light includes forward scattered light S emitted in front of the film 10. ｆ and the backscattered light S emitted backward. ｂ There is a saying.

[0036] The film 10 converts visible light into backscattered light S ｂ Since the backscattered light S ｂ The film 10 appears white due to the incident light I ０ Although a portion of the incident light I is absorbed by the film 10, the film 10 has a low absorptivity for light with wavelengths of 400 nm to 2,000 nm. The film 10 also has an excellent linear transmittance for near-infrared rays. ０ The majority of the transmitted light I ｉ and the forward scattered light S ｆ Therefore, when used in image sensors such as InGaAs sensors, InGaAs / GaAsSb sensors, CMOS sensors, NMOS sensors, and CCD sensors, sharp images with strong contrast (brightness and darkness) can be obtained.

[0037] The linear transmittance of the film according to the embodiment of the present invention to near-infrared rays is measured using a spectrometer such as an ultraviolet-visible-near-infrared spectrophotometer, using the measurement method shown in Figure 2. A specific method for measuring the linear transmittance of the film to near-infrared rays is as described in the Examples below.

[0038] The film according to the embodiment of the present invention preferably has a small incidence angle dependency of the linear transmittance spectrum, and the linear transmittance when the incidence angle of 940 nm near-infrared light is 60° is more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more, compared to the linear transmittance when the incidence angle of 940 nm near-infrared light is 0°.

[0039] In the film according to an embodiment of the present invention, it is preferable that the portion of the curve where the linear transmittance increases monotonically from visible light to near-infrared light shifts to the longer wavelength side as the angle of incidence increases. If the portion of the curve where the linear transmittance increases monotonically from visible light to near-infrared light shifts to the shorter wavelength side as the angle of incidence increases, the shorter wavelength light that is intended to be blocked may be transmitted (light leakage) for obliquely incident light. In contrast, if the film according to an embodiment of the present invention shifts to the longer wavelength side as the angle of incidence increases, this reduces the linear transmittance for light on the shorter wavelength side, which is preferable in that light leakage is less likely to occur.

[0040] Such incidence angle dependency of the film according to the embodiment of the present invention is believed to be due to the fact that the fine particles contained in the first layer of the film, which will be described later, constitute colloidal amorphous aggregates. In the first layer of the film according to the embodiment of the present invention, the fine particles constituting the colloidal amorphous aggregates decrease in linear transmittance for light on the shorter wavelength side as the incidence angle increases because the intensity of scattered light of visible light, particularly visible light on the longer wavelength side, increases. Therefore, when the film according to the embodiment of the present invention is viewed obliquely, the intensity of diffusely reflected light (backscattered light) increases, and the white luminance (L ＊ ) may rise.

[0041] [Average Thickness] The average thickness of the first layer of the film is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1,000 μm or less, more preferably 500 μm or less, and even more preferably 350 μm or less. When the average thickness of the first layer of the film is 1,000 μm or less, sufficient photocurability can be obtained. Furthermore, the lower limit of the average thickness of the first layer of the film is also not particularly limited and can be selected appropriately depending on the purpose, but is preferably 50 μm or more, more preferably 100 μm or more. The upper and lower limits of the average thickness of the first layer of the film can be appropriately combined, for example, 50 μm or more to 1,000 μm or less, 50 μm or more to 500 μm or less, 50 μm or more to 350 μm or less, 100 μm or more to 1,000 μm or less, 100 μm or more to 500 μm or less, 100 μm or more to 350 μm or less, etc.

[0042] In an embodiment of the present invention, the "average thickness" of the first layer of the film means the average value of thicknesses at five points arbitrarily selected from the first layer of the film. The thickness of the first layer of the film can be measured by observing a cross section of the film in the thickness direction using a transmission electron microscope (TEM) (e.g., HT7820, manufactured by Hitachi High-Technologies Corporation). When the film according to an embodiment of the present invention has a single-layer structure consisting of only the first layer, the average thickness of the first layer is the thickness of the film.

[0043] [Materials] The first layer of the film according to the embodiment of the present invention contains a matrix, fine particles dispersed in the matrix, and optionally other components. Preferably, both the matrix and the fine particles are transparent to visible light.

[0044] -Matrix- The material constituting the matrix is ​​not particularly limited as long as it can make the stress relaxation rate of the first layer 70% or more, and can be appropriately selected depending on the purpose. Examples include (meth)acrylic resin, urethane resin, and epoxy resin. These may be used alone or in combination of two or more. In the embodiment of the present invention, "(meth)acrylic" means at least one of "acrylic" and "methacrylic".

[0045] The matrix is ​​preferably formed using a curable resin. The curable resin may be a thermosetting resin or a photocurable resin, but from the viewpoint of mass productivity, it is preferable to use a photocurable resin.

[0046] The matrix is ​​preferably obtained by curing a monomer. The monomer that is the material of the matrix is ​​not particularly limited and can be appropriately selected depending on the purpose, and may be a monofunctional compound or a polyfunctional compound. Furthermore, a mixture of multiple types may be used, but it is preferable to use a monofunctional compound in large quantities.

[0047] Examples of monofunctional compounds usable as matrix materials include benzyl (meth)acrylates. Although there are no particular limitations on the benzyl (meth)acrylates, compounds represented by the following general formula (1) are preferred. In the embodiments of the present invention, "(meth)acrylate" refers to at least one of "acrylate" and "methacrylate."

[0048] In the general formula (1), R represents hydrogen or a phenoxy group.

[0049] Among the compounds represented by general formula (1), phenoxybenzyl (meth)acrylate compounds which are substituted at the o-position or m-position are preferred, and phenoxybenzyl (meth)acrylate compounds which are substituted at the m-position are more preferred.

[0050] The content of the matrix in the first layer of the film is not particularly limited and can be selected appropriately depending on the purpose. When the entire first layer is taken as 100 parts by mass, the content is preferably 30 parts by mass or more and 96 parts by mass or less, more preferably 35 parts by mass or more and 80 parts by mass or less, and even more preferably 40 parts by mass or more and 70 parts by mass or less.

[0051] The matrix content in the first layer of the film can be measured by 3D structural analysis using a real-time 3D analytical FIB-SEM hybrid device (NX9000, manufactured by Hitachi High-Technologies Corporation).

[0052] The fine particles are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include inorganic fine particles, resin fine particles, etc. These may be used alone or in combination of two or more types.

[0053] The inorganic fine particles are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include silica fine particles, titanium oxide fine particles, and zirconia fine particles. Among these, silica fine particles are preferred as the fine particles. The silica fine particles are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include silica fine particles synthesized by the Stöber method and hollow silica fine particles containing air.

[0054] The resin microparticles are not particularly limited and can be appropriately selected depending on the purpose, but microparticles made of at least one selected from the group consisting of polystyrene and polymethyl methacrylate are preferred, and microparticles made of at least one selected from the group consisting of crosslinked polystyrene, crosslinked polymethyl methacrylate, and crosslinked styrene-methyl methacrylate copolymer are more preferred. As such microparticles, for example, polystyrene microparticles or polymethyl methacrylate microparticles synthesized by emulsion polymerization can be used as appropriate. Hollow resin microparticles containing air can also be used.

[0055] Among these, inorganic fine particles are preferred as the fine particles because they are excellent in heat resistance and light resistance, and silica fine particles are more preferred because they can provide a sharp particle size distribution.

[0056] The fine particles preferably form a colloidal amorphous aggregate in the first layer of the film. In the embodiment of the present invention, the term "colloidal amorphous aggregate" refers to an aggregate of colloidal particles having a particle size of 1 nm to 1 μm, which does not have long-range order and does not cause Bragg reflection. This is in contrast to the case where colloidal particles are distributed so as to have long-range order, which results in a so-called colloidal crystal (a type of photonic crystal), and Bragg reflection occurs. In other words, it is preferable that the fine particles (colloidal particles) in the first layer do not form a diffraction grating.

[0057] Colloidal crystals having an ordered structure in which colloidal particles are regularly arranged reflect light of a wavelength corresponding to their lattice constant due to Bragg diffraction. For example, colloidal crystals in which submicron-order colloidal particles are regularly arranged reflect light of wavelengths ranging from ultraviolet light or visible light to infrared light. When such colloidal crystals are used to reflect visible light, they can produce so-called structural colors such as iridescence (rainbow colors). Therefore, the presence or absence of rainbow colors can be visually confirmed to determine whether or not the microparticles constitute a colloidal amorphous aggregate.

[0058] Furthermore, whether or not the microparticles form colloidal amorphous aggregates, and the distribution state of the microparticles in the colloidal amorphous aggregates, can also be confirmed using the average value (La) and standard deviation (Ld) of the distance between the centers of gravity of adjacent microparticles as indicators. The average value (La) of the distance between the centers of gravity of adjacent microparticles is not particularly limited, but is preferably 100 nm or more, more preferably 150 nm or more, even more preferably 175 nm or more, and particularly preferably 200 nm or more. The upper limit of the average value (La) of the distance between the centers of gravity of adjacent microparticles is also not particularly limited, but is preferably 600 nm or less, more preferably 500 nm or less.

[0059] The average value (La) and standard deviation (Ld) of the distance between the centers of gravity of adjacent particles can be calculated from a cross-sectional transmission electron microscope (TEM) image of the first layer of the film. Specifically, when the thickness of the first layer of the film is d, a test piece of the same thickness as the average particle size of the particles is cut out by cutting with a microtome in a direction perpendicular to the thickness direction of the first layer at a position d / 2 relative to the cross-sectional direction (thickness direction), to obtain a sample for TEM observation. From a cross-sectional TEM image containing images of 200 or more particles using a TEM (e.g., HT7820, manufactured by Hitachi High-Tech Corporation), image processing software (e.g., Image J, open source) is used to perform automatic identification Delaunay diagram analysis of the particles, thereby determining the average value (La) and standard deviation (Ld) of the distance between the centers of gravity of adjacent particles. In addition, the coefficient of variation (CV value of the distance) is determined from the average value of the distance between the centers of gravity (hereinafter sometimes referred to as the "average distance between the centers of gravity") and the standard deviation. In the embodiment of the present invention, when determining the distance between the centers of gravity, only particles having a particle size of 150 nm or more are considered, and particles having a particle size of less than 150 nm are not considered.

[0060] The coefficient of variation of the average distance between the centers of gravity of fine particles is not particularly limited, but is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and particularly preferably 25% or more. The upper limit of the coefficient of variation of the average distance between the centers of gravity of fine particles is also not particularly limited, but is preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less. The lower and upper limits of the coefficient of variation of the average distance between the centers of gravity of fine particles can be appropriately combined, and are preferably 10% or more and 45% or less, more preferably 15% or more and 40% or less, even more preferably 20% or more and 40% or less, and particularly preferably 25% or more and 35% or less. When the coefficient of variation of the average distance between the centers of gravity of fine particles is 10% or more, the long-range order is small, and angle-dependent reflection color due to Bragg reflection is difficult to exhibit. Furthermore, when the coefficient of variation of the average distance between the centers of gravity of fine particles is 45% or less, the effect of Mie scattering is small, and the wavelength dependence of light scattering tends to be large.

[0061] The average particle size of the microparticles is not particularly limited and can be selected appropriately depending on the purpose. However, it is preferable to include monodisperse microparticles having an average particle size of at least one-tenth of the wavelength of near-infrared rays. For near-infrared rays having a wavelength of 760 nm to 2,000 nm, the average particle size of the microparticles is more preferably at least 80 nm, even more preferably 150 nm or more, and particularly preferably 200 nm or more. The upper limit of the average particle size of the microparticles is also not particularly limited, but is preferably 300 nm or less. The lower and upper limits of the average particle size of the microparticles can be appropriately combined. For near-infrared rays having a wavelength of 760 nm to 2,000 nm, the average particle size of the microparticles is more preferably 80 nm to 300 nm, even more preferably 150 nm to 300 nm, and particularly preferably 200 nm to 300 nm. The microparticles may also include two or more monodisperse microparticles having different average particle sizes. By using monodisperse microparticles having an average particle size of at least one-tenth of the wavelength of near-infrared rays, the linear transmittance of near-infrared rays can be increased. This differs from Rayleigh scattering in principle.

[0062] The shape of the fine particles is not particularly limited, but is preferably approximately spherical.

[0063] In the embodiment of the present invention, the term "fine particles (plural fine particles)" is also used to mean an aggregate of fine particles. Furthermore, the coefficient of variation (standard deviation / average particle diameter expressed as a percentage) of "monodispersed fine particles" is preferably 20% or less, more preferably 10% or less, and even more preferably 1% or more and 5% or less.

[0064] In the embodiments of the present invention, the average particle size of the microparticles refers to the average particle size determined by a focused ion beam scanning electron microscope (hereinafter sometimes referred to as "FIB-SEM"). Specifically, the average particle size of the microparticles can be calculated by the method described in the examples.

[0065] The content of the fine particles in the first layer of the film is not particularly limited and can be selected appropriately depending on the purpose. When the entire first layer of the film is taken as 100 parts by mass, the content is preferably 6 parts by mass or more and 80 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 60 parts by mass or less.

[0066] The content of fine particles in the first layer of the film can be measured by 3D structural analysis using a real-time 3D analytical FIB-SEM composite device (NX9000, manufactured by Hitachi High-Technologies Corporation).

[0067] --Refractive index-- The refractive index of the matrix for visible light is n Ｍ , the refractive index of the particles is n Ｐ Then, |n Ｍ -n Ｐ| (hereinafter sometimes abbreviated as "refractive index difference") is not particularly limited, but is preferably 0.01 or more and 0.6 or less, and more preferably 0.03 or more and 0.11 or less. If the refractive index difference is less than 0.01, the scattering intensity will be weak, making it difficult to obtain the desired optical properties. Furthermore, if the refractive index difference exceeds 0.6, the linear transmittance for near-infrared rays may decrease. Furthermore, for example, when the refractive index difference is set to 0.6 by using zirconia fine particles (refractive index 2.13) and an acrylic resin, the linear transmittance for near-infrared rays can be adjusted by reducing the thickness. In this way, the linear transmittance for near-infrared rays can also be adjusted, for example, by controlling the film thickness and refractive index difference. Furthermore, depending on the application, it can also be used in combination with a filter that absorbs near-infrared rays. The refractive index for visible light can be represented, for example, by the refractive index for light of 546 nm. Here, unless otherwise specified, the refractive index refers to the refractive index for light of 546 nm.

[0068] Other Components—Other components in the film according to an embodiment of the present invention are not particularly limited and can be appropriately selected depending on the purpose as long as the effects of the present invention are not impaired. For example, a polymerization initiator used when forming the matrix by curing can be included. The polymerization initiator can be appropriately selected depending on the curing method, and may be a thermal polymerization initiator or a photopolymerization initiator.

[0069] Examples of the photopolymerization initiator include carbonyl compounds (e.g., benzoin ether, benzophenone, anthraquinone, thioxane, ketal, acetophenone, 2-hydroxy-2-methylpropiophenone, etc.), sulfur compounds (e.g., disulfides, dithiocarbamates, etc.), organic peroxides (e.g., benzoyl peroxide, etc.), azo compounds, transition metal complexes, polysilane compounds, dye sensitizers, etc. These may be used alone or in combination of two or more.

[0070] The content of the photopolymerization initiator in the film is not particularly limited and can be selected appropriately depending on the purpose. However, it is preferably 0.05 parts by mass or more and 3 parts by mass or less, and more preferably 0.05 parts by mass or more and 2 parts by mass or less, relative to 100 parts by mass of the monomer constituting the matrix.

[0071] [Embodiment Example] An embodiment example of a film will be specifically described with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing an example of a film according to an embodiment of the present invention. The film 10 includes a matrix 12 that is transparent to visible light and transparent microparticles 14 dispersed in the transparent matrix 12. The microparticles 14 preferably form colloidal amorphous aggregates. The film 10 may also include other microparticles that do not disrupt the colloidal amorphous aggregates formed by the microparticles 14.

[0072] As shown schematically in Fig. 3, the film 10 has a substantially flat surface. Here, a substantially flat surface means a surface that does not have an uneven structure of a size that would scatter (diffract) or diffusely reflect visible light or near-infrared light. The film 10 does not contain cholesteric liquid crystals (which broadly include high-molecular-weight liquid crystals, low-molecular-weight liquid crystals, liquid crystal mixtures thereof, and liquid crystal materials obtained by mixing these with a crosslinking agent and solidifying them by crosslinking, etc., and which exhibit a cholesteric phase).

[0073] <Other Layers> The film according to the embodiment of the present invention may have layers other than the first layer, as long as the effects of the present invention are not impaired.

[0074] When the film according to the embodiment of the present invention has other layers, the other layers may be, for example, a filter layer having optical properties different from those of the first layer, a near-infrared absorbing layer, a color filter layer, a print layer, or the like.

[0075] The shape, structure, and size of the other layers are not particularly limited and can be appropriately selected depending on the purpose. For example, the shape may be a film, a plate, or the like.

[0076] <<Near-infrared absorbing layer>> The near-infrared absorbing layer is a filter layer that absorbs near-infrared rays. The near-infrared absorbing layer is preferably disposed on the side where incident light that has entered the near-infrared absorbing layer is transmitted and the transmitted light is emitted. With this configuration, for example, in an infrared sensor, the near-infrared absorbing layer can efficiently absorb near-infrared rays.

[0077] <<Color Filter Layer>> The color filter layer is a filter layer that exhibits black or another color (e.g., yellow, red, blue, pink, brown, etc.). Since the first layer of the film according to the embodiment of the present invention exhibits white, even when a color filter layer is used in combination with the first layer, the color does not interfere with the first layer, thereby improving the design.

[0078] <<Printed Layer>> The printed layer is a layer having a desired printed image such as a color or pattern (for example, letters, pictures, photographs, etc.). By printing the desired printed image using an infrared-transmitting ink, a film having rich colors and a rich design can be obtained without reducing the linear transmittance of the first layer of the film of the embodiment of the present invention to near-infrared rays. Furthermore, since the first layer of the film of the embodiment of the present invention is white, the design can be enhanced by further including a printed layer.

[0079] The print layer is preferably disposed on the surface of the first layer. The print layer may be formed directly on the surface of the first layer, or a transparent film on which the print layer is formed may be disposed on the first layer.

[0080] As the infrared transmitting ink, a known infrared transmitting ink may be selected depending on the application or the wavelength of the near infrared light to be transmitted.

[0081] In the embodiments of the present invention, the terms "on," "disposed on the surface of," "disposed on the side where transmitted light is emitted," and the like of one layer mean that one layer can be connected or bonded to, directly above, or on top of, the other layer, i.e., that another layer may be interposed between one layer and the other layer.

[0082] <Structure> The structure, shape, and size of the film according to the embodiment of the present invention are not particularly limited and can be appropriately selected depending on the purpose. The structure of the film according to the embodiment of the present invention may be a two-dimensional structure (planar structure) or a three-dimensional structure (stereoscopic structure). Specific examples of the film shape include a film formed on the surface of an object having a three-dimensional structure using a known coating method, thereby forming a three-dimensional film. In such embodiments, the shape of the surface of the object having a three-dimensional structure is not particularly limited and can be any shape, such as a shape consisting of part or all of a spherical surface, a shape consisting of an arbitrarily shaped curved surface, or a shape consisting of part or all of a polyhedral surface. However, it is preferable that the surface of the object does not cause light scattering.

[0083] When the film according to the embodiment of the present invention has layers other than the first layer, the average thickness of the film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm to 10 mm, more preferably 10 μm to 1 mm, and even more preferably 10 μm to 500 μm. When the average thickness of the film according to the embodiment of the present invention is 10 μm to 10 mm, the three-dimensional formability is more excellent.

[0084] In an embodiment of the present invention, the "average thickness" of a film refers to the average value of thicknesses at five points arbitrarily selected from the film. The thickness of the film can be measured by observing a cross section of the film in the thickness direction using a transmission electron microscope (TEM) (e.g., HT7820, manufactured by Hitachi High-Technologies Corporation).

[0085] <Manufacturing method> The method for manufacturing a film according to an embodiment of the present invention is not particularly limited, and known methods can be used. Specific examples of the method for manufacturing a film according to an embodiment of the present invention include a step of dispersing fine particles in a curable resin to prepare a curable resin composition (hereinafter, sometimes referred to as a "curable resin composition preparation step"), a step of applying the curable resin composition to the surface of a temporary support (hereinafter, sometimes referred to as an "application step"), and a step of curing the curable resin contained in the curable resin composition applied to the surface of the temporary support to form a first layer (hereinafter, sometimes referred to as a "first layer formation step"), and further include other steps as necessary.

[0086] <<Curable Resin Composition Preparation Step>> The curable resin composition preparation step is a step of dispersing fine particles in a curable resin to prepare a curable resin composition.

[0087] The curable resin in the curable resin composition preparation step contains at least a material that constitutes the matrix of the first layer, and further contains other components of the first layer as needed.

[0088] The fine particles in the curable resin composition preparation step can be appropriately selected from the fine particles of the first layer.

[0089] The method for preparing the curable resin composition is not particularly limited as long as it is a method that can mix the material constituting the matrix, the fine particles, and, if necessary, other components, and can disperse the fine particles in the material constituting the matrix. Examples of the method include a preparation method using a known device, such as a mixing device or a dispersing device, such as a homomixer or a homogenizer (e.g., an ultrasonic homogenizer, a high-pressure homogenizer, etc.).

[0090] The temperature and time for preparing the curable resin composition are not particularly limited and can be appropriately selected depending on the purpose, provided that the temperature for preparation is below the curing temperature of the curable resin composition.

[0091] <<Application Step>> The application step is a step of applying the curable resin composition to the surface of the temporary support.

[0092] In the application step, in order to impart sufficient photocurability to the film, the curable resin composition is preferably applied to the surface of the temporary support so that the average thickness after curing is 1,000 μm or less, more preferably 500 μm or less, and even more preferably 350 μm or less. The thickness of the first layer can be adjusted by the amount of curable resin composition applied in the application step.

[0093] The temporary support is not particularly limited as long as the first layer can be laminated on its surface, and a known release sheet can be used. The temporary support is peeled off when the film is used.

[0094] The release sheet is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include paper such as kraft paper, glassine paper, and wood-free paper; resin films such as polyethylene (PE), polypropylene (PP) (including biaxially oriented polypropylene (OPP), uniaxially oriented polypropylene (CPP), and the like), and polyethylene terephthalate (PET); laminated paper in which paper and a resin film are laminated together; paper that has been sealed with clay, polyvinyl alcohol, or the like and then subjected to a release treatment with a silicone resin or the like on one or both sides; and the like. These may be used alone or in combination of two or more.

[0095] The method for applying the curable resin composition to the surface of the temporary support is not particularly limited and can be appropriately selected from known methods, and examples thereof include coating methods such as dip coating, spray coating, die coating, roll coating, and blade coating, and printing methods.

[0096] <<First Layer Forming Step>> The first layer forming step is a step of forming a first layer by curing the curable resin contained in the curable resin composition applied to the surface of the temporary support.

[0097] The method for curing the curable resin is not particularly limited and can be appropriately selected depending on the properties of the curable resin, the type of polymerization initiator in the curable resin composition, and the like. The method may be heat curing or photocuring, but photocuring is preferred from the viewpoint of mass productivity.

[0098] The temperature and time for thermal curing, and the wavelength, illuminance, and time for photocuring are not particularly limited, and can be appropriately selected depending on the properties of the curable resin, the type of polymerization initiator in the curable resin composition, etc.

[0099] <<Other Steps>> The other steps in the film manufacturing method according to the embodiment of the present invention are not particularly limited, and examples thereof include steps of forming other layers described in the section <Other Layers> under (Film). The method of forming the other layers is not particularly limited, and can be appropriately selected from known methods.

[0100] <Applications> As described above, the film according to the embodiment of the present invention has excellent three-dimensional formability by setting the stress relaxation rate of the first layer to 70% or more. Furthermore, the film according to the embodiment of the present invention can achieve both excellent three-dimensional formability and excellent linear transmittance for near-infrared light. Therefore, the film according to the embodiment of the present invention can be suitably used as an optical filter. For example, the film according to the embodiment of the present invention can be suitably used in image sensors such as InGaAs sensors, InGaAs / GaAsSb sensors, CMOS sensors, NMOS sensors, and CCD sensors, sensing devices using these image sensors (e.g., infrared cameras), communication devices, solar cells, heaters (e.g., heaters using infrared light), and power supply devices (e.g., optically powered devices using infrared light).

[0101] (Optical Module) The optical module of the embodiment of the present invention includes a device equipped with a near-infrared receiving unit, and the film of the embodiment of the present invention arranged in front of the near-infrared receiving unit of the device, and may further include other components as necessary.

[0102] <Device Having a Near-Infrared Receiving Unit> The device having a near-infrared receiving unit is not particularly limited, and examples thereof include a sensing device, a communication device, a solar cell, a heater, and a power supply device. The optical module according to the embodiment of the present invention may include one or more of these devices having a near-infrared receiving unit.

[0103] <Film> The film is a film according to an embodiment of the present invention, and is as described in the (Film) section, so further description will be omitted.

[0104] <Other Components> Other components in the optical module according to the embodiment of the present invention are not particularly limited as long as they do not impair the effects of the present invention, and examples include well-known components that are commonly used in sensing devices, communication devices, solar cells, heaters, and power supply devices.

[0105] <Applications> The optical module according to the embodiment of the present invention includes a film according to the embodiment of the present invention, which has both excellent three-dimensional formability and excellent linear transmittance for near-infrared light. Therefore, the optical module according to the embodiment of the present invention is suitable for use in image sensors such as InGaAs sensors, InGaAs / GaAsSb sensors, CMOS sensors, NMOS sensors, and CCD sensors, sensing devices using these image sensors (e.g., infrared cameras), communication devices, solar cells, heaters (e.g., heaters using infrared light), power supply devices (e.g., optically powered devices using infrared light), and the like.

[0106] (Transfer Film) The transfer film of the embodiment of the present invention has the film of the embodiment of the present invention in a layer form on a temporary support.

[0107] The film in the transfer film of the embodiment of the present invention is the film of the embodiment of the present invention. In addition, as the temporary support in the transfer film of the embodiment of the present invention, the same temporary support as that described in the application step during the production of the film of the embodiment of the present invention can be used.

[0108] The method for forming the film in a layer on the temporary support is not particularly limited, and can be carried out in the same manner as in the film manufacturing method. The temporary support may be disposed on one side or both sides of the film, but it is preferable that the temporary support be disposed on both sides in terms of excellent storage and handling properties of the film.

[0109] Transfer films are advantageous in that they are easy to store and transport, have excellent handleability, and can be easily formed on a substrate by attaching the transfer film to the substrate and peeling off the temporary support, even when the film cannot be formed directly on the substrate.

[0110] (Method for manufacturing a molded body) A method for manufacturing a molded body according to an embodiment of the present invention includes a step of processing a film according to an embodiment of the present invention into a predetermined shape (hereinafter, sometimes referred to as a "processing step"), and may further include other steps as necessary.

[0111] <Processing Step> The processing step is a step of processing the film according to the embodiment of the present invention into a predetermined shape.

[0112] The processing method in the processing step is not particularly limited, and an appropriate processing method can be selected according to the desired shape. For example, press processing, insert molding, extrusion molding, etc. are preferably used when forming into a three-dimensional (3D) shape. Among these, press processing is particularly preferred as the processing method in the processing step.

[0113] The method for pressing the film into a predetermined shape is not particularly limited, and examples thereof include a method using a mold. The mold is not particularly limited and can be appropriately selected depending on the desired shape.

[0114] The heating temperature in the processing step is not particularly limited, but is preferably 80°C to 200°C, more preferably 100°C to 180°C.

[0115] The predetermined shape in the processing step is not limited to a three-dimensional shape, and may be processed into a two-dimensional (2D) shape. When processing into a two-dimensional (2D) shape is desired, a processing method such as stretching can be used.

[0116] In the processing step, the stretching speed in the case of stretching is not particularly limited, but is preferably 50 mm / min to 5,000 mm / min, and more preferably 100 mm / min to 1,000 mm / min.

[0117] (Molded body) The molded body according to the embodiment of the present invention is obtained by thermoforming the film according to the embodiment of the present invention. The molded body according to the embodiment of the present invention has at least the film, and may further have other layers as necessary. The molded body according to the embodiment of the present invention is suitably produced by the manufacturing method of the molded body according to the embodiment of the present invention.

[0118] <Other Layers> The other layers are not particularly limited as long as they do not impair three-dimensional formability and can be appropriately selected depending on the purpose, and examples thereof include a base layer, etc. The film according to the embodiment of the present invention has an excellent stress relaxation rate, and can therefore suitably follow other layers even when laminated thereon.

[0119] <<Substrate Layer>> The material of the substrate constituting the substrate layer is not particularly limited and can be appropriately selected depending on the purpose. Examples include resins such as polyethylene (PE), polypropylene (PP) (including biaxially oriented polypropylene (OPP), uniaxially oriented polypropylene (CPP), etc.), polyethylene terephthalate (PET), polycarbonate (PC), triacetyl cellulose (TAC), polyimide (PI), methyl methacrylate (PMMA), and cycloolefin polymer (COP).

[0120] The linear transmittance of the base layer to near-infrared rays is not particularly limited and can be appropriately selected depending on the purpose, but is preferably in the same range as the linear transmittance of the film according to an embodiment of the present invention to near-infrared rays, and is preferably 45% or more, more preferably 60% or more, even more preferably 65% ​​or more, and particularly preferably 70% or more. The linear transmittance of the base layer can be measured by the same method as the method for measuring the linear transmittance of the film.

[0121] The average refractive index of the substrate layer for visible light is not particularly limited and can be appropriately selected depending on the purpose, but a smaller difference in the average refractive index between the substrate layer and the first layer is preferable because it reduces loss due to interfacial reflection, and is more preferably 0.08 or less, still more preferably 0.03 or less, and particularly preferably 0.01 or less. The average refractive index of the substrate layer for visible light can be measured using an Abbe refractometer (for example, Model: DR-A1, manufactured by Atago Co., Ltd.).

[0122] The average thickness of the substrate layer is not particularly limited as long as it does not impair three-dimensional formability, and can be appropriately selected depending on the purpose.

[0123] The method for laminating the film onto the substrate layer is not particularly limited, and examples thereof include a method of bonding using an adhesive, a method in which the temporary support in the film manufacturing method is replaced with the substrate layer, and a method in which the film is produced directly on the substrate layer, etc.

[0124] <Applications> The molded article according to the embodiment of the present invention has a film according to the embodiment of the present invention, which has excellent three-dimensional formability, and is therefore suitable for use in image sensors such as InGaAs sensors, InGaAs / GaAsSb sensors, CMOS sensors, NMOS sensors, and CCD sensors, sensing devices using these image sensors (e.g., infrared cameras), communication devices, solar cells, heaters (e.g., heaters using infrared rays), power supply devices (e.g., optically powered devices using infrared rays), and the like.

[0125] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples in any way.

[0126] Example 1 50 parts by mass of an acrylic monomer (light acrylate POB-A, 3-phenoxybenzyl acrylate represented by the following structural formula (1), average refractive index at 25°C: 1.566, manufactured by Kyoeisha Chemical Co., Ltd.) (hereinafter sometimes abbreviated as "POB-A") and 50 parts by mass (solid content) of silica fine particles dispersed in methyl ethyl ketone (MEK) (MEK-ST-2040, solid content 40% by mass, manufactured by Nissan Chemical Industries Co., Ltd.) were weighed into a recovery flask. The mixture was then heated in an evaporator (EYEL4, Tokyo Rikakikai Co., Ltd.) under conditions of 200 hPa and 60°C for 30 minutes to distill off the MEK, thereby preparing a curable resin composition. 2 parts by mass of a photopolymerization initiator (2-hydroxy-2-methylpropiophenone, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 100 parts by mass of the obtained curable resin composition and stirred. Next, the composition was applied to the surface of a PET film (MRE75T302, manufactured by Mitsubishi Chemical Corporation) using an applicator, and the resulting film was sandwiched between two PET films (MRE75T302). The curable resin composition was then photopolymerized and cured by irradiating it with ultraviolet light using a UV irradiation device (manufactured by Quark Technology Co., Ltd.). The cured product was peeled off from the two PET films to produce a single-layer film with a thickness of 200 μm.

[0127]

[0128] Example 2 Silica microparticles (MEK-ST-2040, solids content 40% by mass, manufactured by Nissan Chemical Industries, Ltd.) dispersed in methyl ethyl ketone (MEK) were placed in a recovery flask and heated for 30 minutes under conditions of 100 hPa and 60°C using an evaporator (EYEL4, manufactured by Tokyo Rikakikai Co., Ltd.) to distill off the MEK. Next, 50 parts by mass of an acrylic monomer (Viscoat #160, benzyl acrylate represented by the following structural formula (2), average refractive index at 25°C: 1.519, manufactured by Osaka Organic Chemical Industry Co., Ltd.) (hereinafter sometimes abbreviated as "BZA") and 50 parts by mass (solids content) of the silica microparticles from which the MEK had been distilled off were weighed into a sample bottle and stirred for 10 minutes using an ultrasonic disperser (high-powered ultrasonic disperser for laboratory use UP200S, manufactured by Hielscher) to prepare a curable resin composition. To 100 parts by mass of the obtained curable resin composition, 2 parts by mass of a photopolymerization initiator (2-hydroxy-2-methylpropiophenone, manufactured by Tokyo Chemical Industry Co., Ltd.) was added and stirred. Next, using an applicator, the composition was applied to the surface of a PET film (MRE75T302, manufactured by Mitsubishi Chemical Corporation), and the resulting film was sandwiched between two PET films (MRE75T302). Next, ultraviolet light was irradiated using a UV irradiation device (manufactured by Quark Technology Co., Ltd.), and the curable resin composition was photopolymerized and cured. The cured product was peeled off from the two PET films to produce a single-layer film with a thickness of 200 μm.

[0129]

[0130] Example 3 50 parts by mass of acrylic monomer (Light Acrylate POB-A) and 50 parts by mass of silica fine particles (Houtform (registered trademark) Silbol-C M220, manufactured by Fuji Chemical Co., Ltd.) were weighed into a sample bottle and stirred for 10 minutes using an ultrasonic disperser (high-powered ultrasonic disperser for laboratory use, UP200S, manufactured by Hielscher) to prepare a curable resin composition. 2 parts by mass of a photopolymerization initiator (2-hydroxy-2-methylpropiophenone, manufactured by Tokyo Chemical Industry Co., Ltd.) were added to 100 parts by mass of the obtained curable resin composition and stirred. Next, using an applicator, the composition was applied to the surface of a PET film (MRE75T302, manufactured by Mitsubishi Chemical Corporation), and the resulting film was sandwiched between two PET films (MRE75T302). Next, ultraviolet light was irradiated using a UV irradiation device (manufactured by Quark Technology Co., Ltd.) to photopolymerize and harden the curable resin composition. The cured product was peeled off from the two PET films to prepare a single-layer film having a thickness of 200 μm.

[0131] Comparative Example 1 A thermoplastic polyurethane film (thermoplastic elastomer film, Esmer USR PX98, thickness 150 μm, manufactured by Nihon Matai Co., Ltd.) was used as the film of Comparative Example 1.

[0132] Comparative Example 2 A polyethylene film (Polyfilm, HC0110, thickness 120 μm, manufactured by Iwatani Materials Corporation) was used as the film of Comparative Example 2.

[0133] <Evaluation> The films of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for "stress relaxation rate," "Young's modulus," "in-line transmittance," "whiteness," and "three-dimensional formability" by the following methods. The results are shown in Table 1 below.

[0134] <<Stress Relaxation Rate>> A strip-shaped test piece measuring 10 mm in length and 30 mm in width was obtained by cutting at least one direction from the film as the length direction. This strip-shaped test piece was stretched in the length direction at a tensile tester (microscope stretching stage, model: 10073, manufactured by Linkam Co., Ltd.) at a temperature of 25°C and a relative humidity of 45% at a tensile speed of 200 mm / min. The stretching was stopped after stretching to an elongation of 50%. The stress value of the film was continuously measured from the start of stretching until 30 seconds after stretching stopped. The stress value showing the highest stress within the measurement time was designated "A" (N), and the stress value 30 seconds after stretching stopped was designated "B" (N). The stress relaxation rate (%) of the film was calculated based on the following formula 1. A graph showing the change in stress from the start of stretching (0 seconds) to 50 seconds after stretching started is shown in Figure 4. [Formula 1] Stress relaxation rate (%) = (A - B) / A x 100

[0135] <<Young's modulus>> A strip-shaped test piece was obtained by cutting out a length of 10 mm x width of 30 mm from the film, with at least one direction as the length direction. This strip-shaped test piece was pulled in the length direction at a tensile speed of 1 mm / min under an environment of 25 ° C. and 45% relative humidity at a temperature of 25 ° C. and a relative humidity of 45%, and stretched (elongated) to an elongation of 10%. After applying a preliminary force, the test piece was left to stand for 5 minutes. The strain when left to stand for 5 minutes from the application of the preliminary force was defined as ε1, and the stress value was defined as "C" (N). After standing for 5 minutes, the test piece was further pulled in the length direction at 100 mm / min, stretched (elongated) to an elongation of 10%, and then stopped. The strain at the time of stopping was defined as ε2, and the stress value was defined as "D" (N). Young's modulus (MPa) was calculated based on the following formula 2. The strain ε1 was 0.5% and the strain ε2 was 2%. [Equation 2] Young's modulus (MPa) = (stress D - stress C) / (strain ε2 - strain ε1)

[0136] <<Three-dimensional formability>> A square test piece of 30 mm length x 30 mm width was cut from the film, with at least one direction as the length direction. This test piece was heated to 100°C using a hot plate, and a mold (Sealing Stamp Head Wax Seal Stamp Sealing Wax (Tulip, Regular Series), manufactured by WXVOVXW) was pressed against it to obtain a molded product with a three-dimensional structure. The temperature was then lowered to 40°C, and evaluation was performed based on the following evaluation criteria. - Evaluation criteria for three-dimensional formability - A: The desired shape could be produced. B: The desired shape could not be produced.

[0137] <<Linear transmittance to near-infrared rays>> Figure 2 is a schematic diagram showing a method for measuring the linear transmittance to near-infrared rays. An ultraviolet-visible-near-infrared spectrophotometer (UH4150, manufactured by Hitachi High-Tech Science Corporation) was used as a spectroscope, and the linear transmittance to near-infrared rays with a wavelength of 940 nm was measured by the following method. A square test piece of 30 mm in length and 30 mm in width was cut out from the film, with at least one direction as the length direction. The test piece as film 10 was placed at a position so that the distance d from the opening of the integrating sphere 32 was 20 cm, and the measurement was performed. The transmitted light I obtained at this time was ｉ Incident light I with an intensity of ０ The diameter D of the aperture was 1.8 cm, which corresponds to a solid angle of 0.025 sr.

[0138] <<Whiteness>> Using a spectrophotometer (CM-2600-D, manufactured by Konica Minolta Japan, Inc.), measurements were taken using a D65 light source as the standard light source, and the L ＊ The value of this L ＊ The value of 0.01 was taken as the whiteness of the backscattered light of the film.

[0139]

[0140] Comparing Examples 1 to 3 with Comparative Examples 1 and 2, the films of Examples 1 to 3, which had a stress relaxation rate of 70% or more, were excellent in three-dimensional formability. The films of Examples 1 to 3 also had high whiteness and linear transmittance to near-infrared light.

[0141] Examples of the present invention include the following. <1> A film characterized in that the stress relaxation rate calculated by the following formula 1 is 70% or more. [Method for Measuring Stress Relaxation Rate] At least one direction of the film is set as the length direction, and the film is cut into a strip of 10 mm length x 30 mm width. This strip of the test piece is pulled in the length direction at a pulling rate of 200 mm / min using a tensile tester under an environment of 25°C temperature and 45% relative humidity, and stretched to an elongation rate of 50% and stopped. The stress value of the film is continuously measured from the start of pulling to 30 seconds after the stretching has stopped. The stress value that shows the highest stress within the measurement time is then defined as "A" (N), and the stress value 30 seconds after the stretching has stopped is defined as "B" (N), and the stress relaxation rate (%) of the film is calculated based on the following formula 1. [Formula 1] Stress relaxation rate (%) = (A - B) / A × 100 <2> The film according to <1> above, having a Young's modulus of 0.03 MPa or less. <3> The film according to <1> or <2>, which is an optical filter. <4> The film according to any one of <1> to <3>, which has an in-line transmittance of near-infrared rays of 45% or more. <5> The film according to <1>, which has an L measured by the SCE method using a spectrophotometer. ＊The film according to any one of <1> to <4>, wherein the value of (x, y) is 60 or more. <6> The film according to any one of <1> to <5>, containing a matrix and fine particles dispersed in the matrix. <7> The film according to <6>, wherein the fine particles constitute at least colloidal amorphous aggregates. <8> An optical module comprising: a device having a near-infrared receiving unit; and the film according to any one of <1> to <7>, arranged in front of the near-infrared receiving unit of the device. <9> The optical module according to <8>, wherein the device is a sensing device, a communication device, a solar cell, a heater, or a power supply device. <10> A transfer film comprising the film according to any one of <1> to <7> in a layered form on a temporary support. <11> A method for producing a molded product, comprising processing the film according to any one of <1> to <7> into a predetermined shape. <12> A laminate comprising a temporary support and the optical filter according to any one of <1> to <7> laminated on the temporary support. <13> A method for producing a film, comprising: a step of preparing a curable resin composition by dispersing fine particles in a curable resin containing a compound represented by the following general formula (1); a step of applying the curable resin composition to a surface of a temporary support; a step of curing the curable resin contained in the curable resin composition applied to the surface of the temporary support to form a first layer; and a step of peeling off the first layer from the temporary support:

[0142] In the general formula (1), R represents hydrogen or a phenoxy group. <14> The method for producing a film according to <13>, wherein in the applying, the curable resin composition is applied to a surface of a temporary support so that an average thickness after curing is 1,000 μm or less.

[0143] As described above, the present invention has been described based on specific embodiments and examples, but these embodiments and examples are presented merely as examples, and the present invention is not limited to the above embodiments and examples. The above embodiments can be embodied in various other forms, and various combinations, omissions, substitutions, additions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions described in the claims and their equivalents.

[0144] This international application claims priority based on Japanese Patent Application No. 2024-055798, filed on March 29, 2024, the entire contents of which are incorporated herein by reference.

[0145] The film according to the embodiment of the present invention can be used, for example, as an infrared transmission filter used in sensor technology or communication technology, a solar cell, a heater using infrared rays, an optically powered device using infrared rays, and the like.

[0146] 10...Film I ０ … Incident light I ｉ … Transmitted light S ｂ ... Backscattered light S ｆ ...Forward scattered light R ｉ ...interface reflected light 32 ...integrating sphere D ...aperture diameter d ...distance 12 ...matrix 14 ...particle

Claims

1. A film characterized by a stress relaxation rate of 70% or more as calculated by the following formula 1. [Method for measuring stress relaxation rate] The film is cut into a strip of 10 mm length x 30 mm width, with at least one direction as the length direction. This strip of test piece is stretched in the length direction at a tension speed of 200 mm / min using a tensile tester under an environment of 25°C temperature and 45% relative humidity, and stretched to an elongation rate of 50% and then stopped. The stress value of the film is continuously measured from the start of stretching until 30 seconds after the stretching has stopped. The stress value that shows the highest stress within that measurement time is designated as "A" (N), and the stress value 30 seconds after the stretching has stopped is designated as "B" (N), and the stress relaxation rate (%) of the film is calculated based on the following formula 1. [Formula 1] Stress relaxation rate (%) = (A - B) / A x 100 2. The film according to claim 1, having a Young's modulus of 0.03 MPa or less.

3. The film according to claim 1 or 2, which is an optical filter.

4. The film according to any one of claims 1 to 3, which has an in-line transmittance for near-infrared rays of 45% or more.

5. L measured using a spectrophotometer with the SCE method ＊ 5. The film according to claim 1, wherein the value of .gtoreq..times ...

6. The film according to any one of claims 1 to 5, comprising a matrix and microparticles dispersed in said matrix.

7. The film according to claim 6, wherein said microparticles constitute at least a colloidal amorphous aggregate.

8. An optical module comprising: a device equipped with a near-infrared receiving section; and the film according to any one of claims 1 to 7, disposed in front of the near-infrared receiving section of the device.

9. The optical module according to claim 8, wherein the device is a sensing device, a communication device, a solar cell, a heater, or a power supply device.

10. A transfer film characterized by having the film according to any one of claims 1 to 7 layered on a temporary support.

11. A method for producing a molded article, comprising processing the film according to any one of claims 1 to 7 into a predetermined shape.

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