Infrared reflection body 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] 2. Description of the Related 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 streaks formed by rubbing a polymeric material onto a solid substrate, and a metal film that is adhered and formed between the streaks" (Claim 1).

[0004] Furthermore, Patent Document 2 (JP Patent Publication No. 2004-300283) discloses a resin having infrared reflectivity, which is a resin containing an infrared absorber and an infrared reflector, and 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 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] JP 2003-279738 A [Patent Document 2] JP 2004-300283 A [Patent Document 3] JP 2010-286644 A 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, which makes the production process complicated and costly, and the reflected 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 of wavelengths 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) each having a cholesteric liquid crystal phase fixed 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 PRESENTLY PREFERRED EMBODIMENTS Accordingly, an object of the present invention is to provide an infrared reflector which has a high infrared reflectance and excellent polarization characteristics 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 composed 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 outer 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 an innumerable number of pores are arranged adjacent to one another when the surface of the resin layer is viewed from a direction substantially normal to the surface. The pores are adjacent to each other through 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 mesh-like shape, and the pores are spaced apart from one another by 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, since it is possible to realize an infrared reflector that exhibits infrared reflective performance using only resin molded by an existing molding device without requiring special additives or post-processing, it is easy to manufacture and has low manufacturing costs. In other words, according to the present invention, it is possible to provide an infrared reflector having high infrared reflectance and excellent polarization characteristics without complicated manufacturing processes, structure, and composition, and a method for reflecting infrared rays using the same.

[0014] In the infrared reflector of the present invention, it is preferable that the unit structure of the resin forming the resin layer is 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 is more than 45%.

[0016] The infrared reflector of the present invention is preferably capable of polarizing and reflecting infrared rays. More preferably, 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. Effect 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 characteristics without complicating the manufacturing process, structure and composition, and an infrared reflection method using the same. [Brief description 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. [Diagram 2] 1 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°. [Diagram 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 and Comparative Examples 1 and 2 of the present invention and a comparative infrared reflector 2 (the upper row is Example 1, the middle row is Example 2, and the lower row is Comparative Example 1). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Representative embodiments of the infrared reflector, the method for producing 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 reflective surface is composed of a resin layer containing an oxymethylene homopolymer or an oxymethylene copolymer, the resin layer has pores on its infrared reflective surface, the L diameter of the pores is 10 to 1000 nm, and the pores are densely packed.

[0022] The resin layer constituting the infrared reflective 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 a homopolymer or copolymer having oxymethylene as a unit structure represented by the formula (where n is an integer), and may be a so-called copolymer or 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 only oxymethylene). The oxymethylene homopolymer or oxymethylene copolymer may contain various additives that are commonly used within the range that does not impair the effects of the present invention.

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

[0024] In the infrared reflector of the present invention, the infrared reflecting surface of the resin layer has pores, the L diameter of the pores is 10 nm to 1000 nm, and when the surface of the resin layer is viewed from a direction approximately normal to the surface, countless pores are arranged adjacent to each other and densely packed, and the pores are adjacent to each other with partitions having a thickness of 200 nm or less, so that the relationship between the pores and the partitions forms a honeycomb or mesh-like state, and the pores are spaced apart from each other by 1 μm or less on the surface. 2 With such a configuration, the infrared reflector of the present invention can reflect infrared rays in the far infrared region, that is, wavelengths 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 a peak of 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 density of the pores is insufficient on the infrared reflective surface of the resin layer, the infrared reflectance is low and polarized light is not reflected. In addition, it is desirable that the pores are densely packed from the surface to the inside of the resin layer.

[0026] It has been experimentally confirmed 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 size of the pores, and is at least 4000 to 650 cm -1 At least two peaks at 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 it has been confirmed through experiments that the infrared reflectance is as follows depending on whether the resin layer is an oxymethylene copolymer or an oxymethylene homopolymer. Infrared reflectance when the pore size L is 100-200 nm Oxymethylene copolymer: 80% Oxymethylene homopolymer: 60-100% Infrared reflectance when the pore size L is 200-400 nm Oxymethylene copolymer: 40~75% Oxymethylene homopolymer: 60-100% Infrared reflectance when the pore diameter L is 400 to 1000 nm Oxymethylene copolymer: 30~45%

[0028] The infrared reflector of the present invention can be manufactured 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 reflecting surface of the resin layer can be adjusted by controlling the conditions such as the cooling rate and pressure during molding. In other words, the present inventors have found that the infrared reflectance can be improved by slow cooling regardless of the molding method.

[0029] Among them, it is presumed that the surface pore shape changes due to the pressing force during cooling, and from this point of view, it is considered that solidification extrusion is advantageous. The crystallinity cannot be measured because complete crystallization cannot be obtained, but when the relative crystallinity was evaluated by melting calorimetry using DSC, it was confirmed that those with high infrared reflectance have high heat of fusion, as shown in Table 1 below. In particular, the present inventors found that when the heat of fusion is less than 155 mJ / mg, the maximum value of infrared reflectance is less than 45%, whereas when the heat of fusion is 155 mJ / mg or more, the maximum value of infrared reflectance exceeds 80%. From this, the present inventors also considered that the solidification extrusion method, which is a molding method by slow cooling that easily increases the crystallinity, is preferable for improving reflectance.

[0030] The infrared reflector of the present invention not only has high infrared reflectance but also has 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 is 34% to 40%, with a maximum variation (change) of 49 points (%). The inventors believe that the polarization properties are expressed 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 expressed.

[0031] Here, in the infrared reflector of the present invention, a layer that does not prevent 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 present. The pores can be observed on both the surface and the cross section of the resin layer, and in particular, if the pores on the surface of the resin layer made of the oxymethylene homopolymer or the oxymethylene copolymer and the surface obtained by arbitrarily cutting the resin layer satisfy the provisions 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 (e.g., press molding, injection molding, extrusion molding, solidification extrusion molding) to obtain a resin molded body made of an oxymethylene homopolymer or oxymethylene copolymer having dense pores with an L diameter of 10 to 1000 nm on the surface. The infrared reflecting surface made of the above-mentioned resin layer has a high infrared ray reflectance of 650 to 4000 cm despite being made of resin. -1 In the region, it has two or more infrared reflection peaks and the maximum infrared reflectance exceeds 45%. In addition, when a resin molded product made of an 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

[0034] Example 1 Tenac 5010 manufactured by Asahi Kasei Corporation was used as the raw material, and solidification extrusion molding was performed while cooling the molten resin. An infrared reflector 1 was produced in which the infrared reflective surface was composed of a resin layer made of an oxymethylene homopolymer, and the resin layer had dense pores with an L diameter of 80 to 500 nm on the infrared reflective surface. The time for cooling the molten resin to room temperature was adjusted to between 40 minutes and 60 minutes. The cooling time is defined as slow cooling, where the resin temperature is lowered from the melting temperature to room temperature over a period of 10 minutes or more. Rapid cooling is defined as lowering the resin temperature from the melting temperature to room temperature in a period of 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 pores with an L diameter of 60 to 300 nm densely packed 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. The molten resin was then cooled to room temperature within 10 minutes to produce a comparative infrared reflector 1, whose infrared reflective surface was composed of a resin layer made of an oxymethylene copolymer, and the resin layer had pores on the infrared reflective surface.

[0037] Comparative Example 2 The same materials as those in Example 2 were used as raw materials, and the molten resin was pressed in a press (hydraulic molding press (Kodaira Seisakusho, PY-25) at 100 k / cm 2 By molding at a temperature of 200°C (and a mold heater set temperature of 200°C), the molten resin was cooled to room temperature within 10 minutes to produce a comparative infrared reflector 2, whose infrared reflective surface was composed of a resin layer made of an oxymethylene copolymer and whose resin layer did not have pores on the infrared reflective surface.

[0038] [evaluation] The above 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 to 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 above conditions. The maximum value of the infrared reflectance obtained by the above measurement method is defined as the maximum reflectance. For the infrared reflector 2 and the comparative infrared reflector 2 of the above Example 2 and Comparative Example 2, infrared reflectance measurement (confirmation of polarization characteristics) was performed using a polarizer. The set angle of the polarizer is defined as the polarization angle. In the evaluation of the polarization characteristics, the polarization angle at which the infrared reflected light showed the maximum reflectance 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 1-2, Comparative Example 2) Using a scanning electron microscope S-4800 manufactured by Hitachi High-Technologies Corporation, a micrograph (SEM image) was taken from the direction approximately normal to the infrared reflective surface made of the resin layer under conditions of an accelerating voltage of 1.0 kV and no pretreatment. The results are shown in Table 1.

[0042] (4) Electron microscope measurement method B (Comparative example 1) Using a scanning electron microscope JSM-7800F manufactured by JEOL Ltd., a micrograph (SEM image) was taken from the direction approximately normal to the infrared reflective surface made of the resin layer under conditions of an accelerating voltage of 0.5 kV and 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 view of the SEM image shown in Figure 4. Specifically, a frame with an inner dimension of 1 μm square was placed at an arbitrary position on the SEM image, and the number of pores in the frame was visually confirmed. The number of pores was calculated by counting the number of pores that were contained within the frame as 1, and the number of pores that were not contained within the frame and protruded from the frame as 1 / 2. The results are shown in Table 1.

[0044] [Table 1]

[0045] From the results shown in Table 1 and Figure 1, it can be seen 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 reflectance. Also, from Figure 2, it can be seen 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 infrared rays having wavelengths of 8.3 to 10 μm (1200 to 1000 cm -1 ), it can be used in thermography and carbon dioxide laser fields (λ=10.6μm), which use far-infrared light with wavelengths of 4 to 1000μm. It can also be used in infrared noise filters that selectively reflect infrared light with specific wavelengths and polarization angles to remove noise, in infrared sensors such as sensors for autonomous driving and occupancy detection sensors, in remote sensing technologies such as road surface icing sensors, agricultural crop sensors, and soil sensors, as well as in the security field, including personal robots and crime prevention systems.

[0047] Furthermore, according to the present invention, it is possible to produce a 1m square infrared polarizing reflector using existing molding machines, so it can be used in a highly sensitive sensor that detects weak signals. In addition, because the variation in reflectance due to the polarization angle is large (approximately 40%), the number of times that infrared light needs to be polarized and reflected to remove noise can be reduced, making it possible to reduce the number of infrared reflectors required.

[0048] Furthermore, by installing two or more infrared image sensors in parallel, one of which uses the infrared reflector of the present invention, and the other a reflector such as metal, the difference data of the infrared images can be processed by an image processing device, making it possible to distinguish and highlight polarized objects and non-polarized objects in the image with high definition. 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 definition.

Claims

1. The infrared reflective surface is composed of a resin layer made of a resin containing an oxymethylene copolymer, the resin layer has pores on the infrared reflective surface, and the maximum length of a straight line connecting any two points on the outer periphery of the pores is 60 to 500 nm; The pores are densely packed, The resin has a heat of fusion of 155 mJ / mg or more; the resin layer is made of a resin molded body obtained by solidifying and extruding the molten resin while lowering the resin temperature from the melting temperature to room temperature over a period of 10 minutes or more; 600-1300cm －１ The maximum infrared reflectance in the wave number region is more than 80%. An infrared reflector characterized by:

2. exhibiting polarized reflection in infrared light; 2. The infrared reflector according to claim 1 ,

3. At the wave number showing maximum infrared reflectance, The maximum infrared reflectance changes by 15 points or more depending on the infrared polarization angle.

3. The infrared reflector according to claim 2 .

4. A method for reflecting infrared rays using the infrared reflector according to any one of claims 1 to 3.

Images