Infrared reflector and infrared reflection method using the same

Abstract

To provide an infrared reflection body which does not have complicated manufacturing process, structure and composition, and has high infrared reflectance and excellent polarization characteristics, and an infrared reflection method using the same.SOLUTION: An infrared reflection body has an infrared reflection surface composed of a resin layer composed of a resin containing an oxymethylene copolymer, wherein the resin layer has pores on the infrared reflection surface, a maximum value of a length of a straight line connecting arbitrary two points on the outer periphery of the pores is 60 to 500 nm, the pores are dense, melt heat of the resin is 155 mJ / mg or more, the resin layer is composed of a resin molding obtained by solidifying, extruding and molding the molten resin while lowering a resin temperature to a room temperature from a melting temperature for 10 minutes or more, and a maximum value of reflectance of infrared in a wavelength region of 600 to 1,300 cm-1 exceeds 80%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an infrared reflector and a method for reflecting infrared rays using the same. [Background technology]

[0002] BACKGROUND ART Infrared polarizing reflective molded articles have been used as infrared filters and infrared polarizing filters.

[0003] For example, Patent Document 1 (JP Patent Publication No. 2003-279738) discloses a polarizing filter that is "characterized in being composed of a plurality of stripes formed by rubbing a polymer material onto a solid substrate, and a metal film that is adhered and formed between each of the stripes" (Claim 1).

[0004] Furthermore, Patent Document 2 (JP 2004-300283 A) discloses a resin having infrared reflectivity, which is a resin to which an infrared absorber and an infrared reflector have been added, and which is characterized by having a specific infrared reflectance in a specific wavelength range (Claim 1).

[0005] Furthermore, Patent Document 3 (JP 2010-286644 A) discloses an infrared light reflector having a substrate and at least four light-reflecting layers X1, X2, X3, and X4, each having a fixed cholesteric liquid crystal phase, in this order from the substrate side on at least one surface of the substrate, and having a specific relationship with respect to wavelength (Claim 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-279738 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-300283 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-286644 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the polarizing filter of Patent Document 1 requires streak formation and metal vapor deposition during its production, making the production process complicated and costly. In addition, the reflection wavelength peak is broad, making it unsuitable as an infrared filter.

[0008] Furthermore, the resin with infrared reflectivity in Patent Document 2 is based on the premise that an infrared absorber and an infrared reflector are added to a polyacetal resin, and is an infrared reflector in the near-infrared region, that is, wavelengths of 600 to 1200 nm, but there is no mention of reflection of infrared rays in the far-infrared region.

[0009] Furthermore, the infrared light reflector of Patent Document 3 requires at least four light-reflecting layers (laminated structure) formed by fixing a cholesteric liquid crystal phase on at least one surface of the substrate, resulting in a complex structure and making it impossible to reflect polarized light.

[0010] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an infrared reflector that has a high infrared reflectance and excellent polarization properties without requiring a complicated manufacturing process, structure, or composition, and a method for reflecting infrared rays using the same. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides: the infrared reflective surface is made of a resin layer containing an oxymethylene homopolymer or an oxymethylene copolymer, the resin layer has pores on the infrared reflective surface, the maximum length of a straight line connecting any two points on the periphery of the pore (hereinafter also referred to as "L diameter") is 10 nm to 1000 nm, the pores are densely packed; The present invention provides an infrared reflector characterized by:

[0012] Here, the term "densely packed pores" in the infrared reflector of the present invention refers to a state in which countless pores are arranged adjacent to one another when the surface of the resin layer is viewed from the direction substantially normal to the surface. The pores are adjacent to each other with partition walls having a thickness of 200 nm or less, so that the relationship between the pores and the partition walls forms a honeycomb or network-like state, and the pores are spaced apart from one another at intervals of 1 μm on the surface. 2 It refers to a state in which 5 to 34 pores are present per unit area. However, the shape, size and arrangement (direction, etc.) of the pores are not particularly limited as long as they do not impair the effects of the present invention, and various embodiments are possible.

[0013] According to the present invention having the above-mentioned configuration, an infrared reflector that exhibits infrared reflective performance can be realized using only resin molded using existing molding equipment without the need for special additives or post-processing, which makes manufacturing easy and low cost. In other words, according to the present invention, it is possible to provide an infrared reflector that has high infrared reflectivity and excellent polarization properties without complex manufacturing processes, structure, or composition, and a method of reflecting infrared using the same.

[0014] In the infrared reflector of the present invention, the unit structure of the resin forming the resin layer is preferably only oxymethylene.

[0015] The infrared reflector of the present invention has a wavelength of 600 to 1300 cm -1 It is preferable that the maximum infrared reflectance in the wave number region of 1000 or more exceeds 45%.

[0016] The infrared reflector of the present invention is preferably capable of polarizing and reflecting infrared rays.Moreover, it is more preferable that the maximum infrared reflectance changes by 15 points or more depending on the infrared polarization angle at the wave number showing the maximum infrared reflectance.

[0017] Furthermore, the present invention also relates to a method for reflecting infrared rays using the infrared reflector of the present invention having the above-mentioned configuration. [Effects of the Invention]

[0018] According to the present invention, it is possible to reliably provide an infrared reflector having high infrared reflectance and excellent polarization properties without requiring a complicated manufacturing process, structure, or composition, and a method for reflecting infrared rays using the same. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a graph showing the infrared reflectance of infrared reflectors 1 and 2 and comparative infrared reflectors 1 and 2 obtained in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention. [Figure 2] 10 is a graph showing polarization characteristics based on the reflectance of infrared light reflected by the infrared reflector 2 obtained in Example 2 of the present invention at polarization angles of 0°, 90°, and 180°. [Figure 3] 1 is a graph showing polarization characteristics based on the reflectance of infrared light reflected by comparative infrared reflector 2 obtained in Comparative Example 2 of the present invention at polarization angles of 0°, 90°, and 180°. [Figure 4] 1 shows SEM images of infrared reflectors 1 and 2 obtained in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2, and a comparative infrared reflector 2 (top row: Example 1, middle row: Example 2, bottom row: Comparative Example 1). DETAILED DESCRIPTION OF THE INVENTION

[0020] Representative embodiments of the infrared reflector, the method for manufacturing the infrared reflector, and the method for reflecting infrared rays using the same of the present invention will be described in detail below, but the present invention is not limited to these.

[0021] The infrared reflector of the present invention is characterized in that the infrared reflecting surface is composed of a resin layer containing an oxymethylene homopolymer or an oxymethylene copolymer, the infrared reflecting surface of the resin layer has pores, the L diameter of the pores is 10 to 1000 nm, and the pores are densely packed.

[0022] The resin layer constituting the infrared reflecting surface contains an oxymethylene homopolymer or an oxymethylene copolymer, and the oxymethylene homopolymer or the oxymethylene copolymer is represented by the following formula (1): [ka] The resin layer is preferably a homopolymer or copolymer having oxymethylene as a unit structure (where n is an integer), and may be a copolymer or a homopolymer, but from the viewpoint of high infrared reflectance, it is preferably a homopolymer (i.e., the unit structure of the resin constituting the resin layer is oxymethylene only). The oxymethylene homopolymer or oxymethylene copolymer may contain various commonly used additives within the range that does not impair the effects of the present invention.

[0023] The present inventors have discovered that a molded article made of a resin layer containing the above-mentioned oxymethylene in its unit structure exhibits polarized reflection of infrared rays in a specific wavelength range with a surface structure molded by an existing molding method, without requiring any of the conventional processing steps such as adding an infrared reflecting agent, providing a wire grid on the infrared reflective surface, or laminating a cholesteric liquid crystal layer, and have thus completed the present invention.

[0024] In the infrared reflector of the present invention, the resin layer has pores on its infrared reflecting surface, the pores having an L diameter of 10 nm to 1000 nm, and when the surface of the resin layer is viewed from a direction substantially normal to the surface, countless pores are arranged adjacent to one another and densely packed, and the pores are adjacent to each other with partition walls having a thickness of 200 nm or less, so that the relationship between the pores and the partition walls forms a honeycomb or network-like state, and the pores are spaced apart from one another at intervals of 1 μm 2 With this configuration, the infrared reflector of the present invention can reflect light in the far-infrared region, which has a wavelength of 8 to 12.5 μm (1200 to 800 cm). -1 ) and has a maximum infrared reflectance of 30% (no surface pores) to 98% (homopolymer surface aligned pores), and further has an infrared reflectance of 600 to 1300 cm -1It achieves a maximum infrared reflectance of 45% or more in the wave number range.

[0025] The shape, size, and arrangement (direction, etc.) of the pores are not particularly limited as long as they do not impair the effects of the present invention, and various embodiments are possible, but the inventors have confirmed through experiments that if there are no pores or the pores are insufficiently dense on the infrared reflective surface of the resin layer, the infrared reflectivity is low and polarized light is not reflected. Furthermore, it is desirable that the pores are densely packed from the surface to the interior of the resin layer.

[0026] It has also been confirmed through experiments that when the pores are closely adjacent and regularly arranged (aligned) both vertically and horizontally on the infrared reflective surface of the resin layer, the infrared reflectance tends to be high. However, the infrared reflection peak wavelength does not change depending on the pore size, and is at least 4000 to 650 cm -1 At least two peaks in the range of 900 to 980 cm -1 and 1100-1150cm -1 ).

[0027] The pores in the infrared reflective surface of the resin layer may have an L diameter in the range of 10 to 1000 nm, but experiments have confirmed that the infrared reflectivity is as follows depending on whether the resin layer is an oxymethylene copolymer or an oxymethylene homopolymer. Infrared reflectance when the pore diameter is 100 to 200 nm Oxymethylene copolymer: 80% Oxymethylene homopolymer: 60-100% Infrared reflectance when the pore diameter is 200 to 400 nm Oxymethylene copolymer: 40~75% Oxymethylene homopolymer: 60-100% Infrared reflectance when the pore diameter is 400 to 1000 nm Oxymethylene copolymer: 30~45%

[0028] The infrared reflector of the present invention can be produced by various molding methods using the oxymethylene homopolymer or oxymethylene copolymer that constitutes the resin layer, and the shape, size, and arrangement of the pores in the infrared reflective surface of the resin layer can be adjusted by controlling the conditions during molding, such as the cooling rate and pressure. That is, the present inventors have found that infrared reflectance can be improved by slow cooling regardless of the molding method.

[0029] Among these, it is believed that the pressing force during cooling changes the shape of the surface pores, and from this perspective, solidification extrusion is considered to be advantageous. Although crystallinity cannot be measured because complete crystallization is not possible, when the relative crystallinity was evaluated by melting calorimetry using DSC, it was confirmed that materials with high infrared reflectance had high heats of fusion, as shown in Table 1 below. In particular, the inventors found that when the heat of fusion was less than 155 mJ / mg, the maximum infrared reflectance was less than 45%, whereas when the heat of fusion was 155 mJ / mg or more, the maximum infrared reflectance exceeded 80%. Based on this, the inventors also considered that solidification extrusion, a molding method using slow cooling that easily increases crystallinity, is preferable for improving reflectance.

[0030] The infrared reflector of the present invention not only has high infrared reflectance but also polarization properties. That is, when the polarization angle is 0°, the infrared reflectance is 83%, but when the polarization angle is 90°, the infrared reflectance falls to 34% to 40%, a fluctuation (change) of up to 49 points (%). The inventors believe that the polarization properties are exhibited by the presence of pores on the surface of the resin layer, because when there are no pores on the surface of the resin layer (press molding), the infrared reflectance is 30% and no polarization properties are exhibited.

[0031] In the infrared reflector of the present invention, a layer that does not impede infrared transmission may be laminated on the infrared reflecting surface. Specifically, a skin layer made of an oxymethylene homopolymer or an oxymethylene copolymer and having a thickness of 10 to 50 μm may be provided. The pores can be observed on both the surface and cross section of the resin layer. In particular, if the pores on the surface of the resin layer made of the oxymethylene homopolymer or the oxymethylene copolymer and on the surface obtained by arbitrarily cutting the resin layer satisfy the requirements of the claims, the cut surface can be used as an infrared reflector.

[0032] The infrared reflector of the present invention can be produced by adjusting the molding conditions when producing a resin molded body using an existing molding method (for example, press molding, injection molding, extrusion molding, or solidification extrusion molding) to obtain a resin molded body made of an oxymethylene homopolymer or oxymethylene copolymer having densely packed pores with an L diameter of 10 to 1000 nm on the surface. The infrared reflecting surface made of the above-mentioned resin layer is made of resin, but has a reflective surface of 650 to 4000 cm. -1 In this region, the resin has two or more infrared reflection peaks, and the maximum infrared reflectance exceeds 45%. When a resin molded product made of oxymethylene homopolymer is used, the maximum infrared reflectance reaches 98%.

[0033] The infrared reflector of the present invention will be described in more detail below using examples, but it goes without saying that the present invention is not limited to these examples. [Example]

[0034] Example 1 Tenac 5010 manufactured by Asahi Kasei Corporation was used as the raw material, and solidification extrusion molding was performed while the molten resin was cooled. Infrared reflector 1 was produced, in which the infrared reflective surface was composed of a resin layer made of oxymethylene homopolymer, and the resin layer had dense pores with L diameters of 80 to 500 nm on the infrared reflective surface. The time required to cool the molten resin to room temperature was adjusted to between 40 and 60 minutes. Regarding the cooling time, slow cooling refers to lowering the resin temperature from the melting temperature to room temperature over a period of 10 minutes or more. Rapid cooling refers to lowering the resin temperature from the melting temperature to room temperature in less than 10 minutes.

[0035] Example 2 The procedure was the same as in Example 1, except that the raw material was Hostaform manufactured by Celanese Japan Co., Ltd. An infrared reflector 2 was produced in which the infrared reflective surface was composed of a resin layer made of an oxymethylene copolymer, and the resin layer had densely packed pores with an L diameter of 60 to 300 nm on the infrared reflective surface.

[0036] Comparative Example 1 The same materials as in Example 2 were used as raw materials, and the molten resin was molded using an injection molding machine, and the molten resin was cooled to room temperature within 10 minutes to produce comparative infrared reflector 1, whose infrared reflective surface was composed of a resin layer made of oxymethylene copolymer, and the resin layer had pores on the infrared reflective surface.

[0037] Comparative Example 2 The same materials as in Example 2 were used as raw materials, and the molten resin was pressed in a hydraulic press (Kodaira Seisakusho, PY-25) at 100 kJ / cm 2 The molten resin was cooled to room temperature within 10 minutes by molding at a temperature of 200°C (with a mold heater set temperature of 200°C), and comparative infrared reflector 2 was produced, in which the infrared reflective surface was composed of a resin layer made of oxymethylene copolymer, and the resin layer had no pores on the infrared reflective surface.

[0038] [evaluation] The above-mentioned infrared reflectors 1 and 2 and comparative infrared reflectors 1 and 2 were evaluated by the following measurements.

[0039] (1) Infrared reflectance The infrared reflectance of the surface (infrared reflecting surface) of the resin layer was measured by a microscopic infrared method using a Fourier transform infrared spectrometer manufactured by PerkinElmer Japan Co., Ltd. (Examples 1 and 2, Comparative Example 2: Spotlight 400, Comparative Example 1: Spectrum One) at a resolution of 4 cm. -1 , Number of scans: 32, and measurement range: 4000~650cm -1 The infrared reflectance (%) was measured under the following conditions. The maximum value of the infrared reflectance obtained by the above measurement method is defined as the maximum reflectance. Furthermore, for the infrared reflector 2 and the comparative infrared reflector 2 of Example 2 and Comparative Example 2, infrared reflectance measurement (confirmation of polarization characteristics) was carried out using a polarizer. The set angle of the polarizer is defined as the polarization angle. In the evaluation of polarization characteristics, the polarization angle at which the maximum reflectance was observed for reflected infrared light was defined as 0°. The results are shown in Figures 2 and 3.

[0040] (2) Heat of fusion The heat of fusion (mJ / mg) was measured using a DSC7020 manufactured by Hitachi High-Tech Science Corp. under the following conditions: measurement range: 0 to 200°C, heating rate: 10°C / min, hold: 5 min, sampling time: 0.2 s, and sample weight: 8.0 mg. The results are shown in Table 1.

[0041] (3) Electron Microscope Measurement Method A (Examples 1 and 2, Comparative Example 2) Using a scanning electron microscope S-4800 manufactured by Hitachi High-Technologies Corporation, micrographs (SEM images) were taken from the direction approximately normal to the infrared reflective surface of the resin layer at an accelerating voltage of 1.0 kV without any pretreatment. The results are shown in Table 1.

[0042] (4) Electron microscope measurement method B (Comparative example 1) Using a JEOL JSM-7800F scanning electron microscope, SEM images were taken from the direction approximately normal to the infrared reflecting surface of the resin layer at an accelerating voltage of 0.5 kV after pretreatment with platinum coating. The results are shown in Table 1.

[0043] (5) Pore size The dimensions of the pores in the resin layer were measured using the enlarged SEM image shown in Figure 4. Specifically, a frame with an inner dimension of 1 μm square was placed at a random position on the SEM image, and the number of pores within the frame was visually counted. A pore that fit within the frame was counted as 1, and a pore that was partially outside the frame and protruded beyond the frame was counted as 1 / 2, and the number of pores was then added up. The results are shown in Table 1.

[0044] [Table 1]

[0045] The results shown in Table 1 and Figure 1 indicate that the infrared reflector of the present invention has an infrared reflective surface composed of a resin layer containing an oxymethylene homopolymer or an oxymethylene copolymer, has pores on the infrared reflective surface of the resin layer, and has an L diameter of 60 to 500 nm and a heat of fusion of 155 mJ / mg or more, thereby exhibiting high infrared reflectivity. Furthermore, Figure 2 indicates that the infrared reflector reflects polarized infrared light and has polarization properties.

[0046] As described above, the infrared reflector of the present invention has high infrared reflectance and is resistant to light having a wavelength of 8.3 to 10 μm (1200 to 1000 cm -1 Because it polarizes and reflects in the far-infrared region of 4 to 1000 μm, it can be used in thermography and carbon dioxide lasers (λ=10.6 μm), which use far-infrared light with wavelengths of 4 to 1000 μm. It can also be used in infrared noise filters that selectively reflect infrared light of specific wavelengths and polarization angles to remove noise, in infrared sensors for autonomous driving and occupancy detection sensors, in remote sensing technologies such as road surface icy sensors, agricultural crop sensors, and soil sensors, and in the security field, including personal robots and crime prevention systems.

[0047] Furthermore, according to the present invention, it is possible to produce 1m square infrared polarized reflectors using existing molding machines, making them suitable for use in highly sensitive sensors that detect weak signals. Furthermore, because the reflectivity varies significantly with the polarization angle (approximately 40%), the number of times infrared light needs to be polarized and reflected to remove noise can be reduced, thereby reducing the number of infrared reflectors required.

[0048] Furthermore, by installing two or more infrared image sensors in parallel, one using the infrared reflector of the present invention and the other using a reflector such as metal, and processing the difference data of the infrared image with an image processing device, it becomes possible to distinguish and highlight polarized and non-polarized objects in the image with high resolution. For example, it is possible to realize a high-performance night vision device that can distinguish and detect polarized artificial objects and distinguish and highlight non-polarized natural objects (such as the human body) with high resolution.

Claims

1. A resin containing an oxymethylene copolymer is melted, The molten resin is solidified and extruded while lowering the resin temperature from the melting temperature to room temperature over 10 minutes or more to form a resin molded body, The resin molding has an infrared reflective surface in which the maximum length of a straight line connecting any two points on the periphery of a pore is 60 to 500 nm, the pores are densely packed, the heat of fusion of the resin is 155 mJ / mg or more, and the heat of fusion is 600 to 1300 cm -1 to obtain an infrared reflector having a maximum infrared reflectance of more than 80% in the wave number region of A method for producing an infrared reflector, characterized by:

2. The infrared reflector exhibits polarized reflection of infrared light. The method for producing an infrared reflector according to claim 1,

3. For the infrared reflector, at the wave number showing the maximum infrared reflectance, the maximum infrared reflectance changes by 15 points or more depending on the infrared polarization angle, The method for producing an infrared reflector according to claim 2,

4. A method for reflecting infrared rays, comprising reflecting infrared rays using an infrared reflector obtained by the method for producing an infrared reflector according to any one of claims 1 to 3.

Images