JP6912229B2 - Reflective member and its manufacturing method - Google Patents

Description

The present invention relates to a reflective member that exhibits high reflectance in a plurality of wavelength ranges in a wavelength range of light of 350 nm or more and 1100 nm or less, and a method for producing the same.

In recent years, much attention has been paid to methods for efficiently cultivating plants. One of them is a plant factory that grows plants by controlling temperature, humidity, light intensity, CO _{2 concentration, etc. in equipment such as containers.} In plant factories, LEDs, fluorescent lamps, and the like are used as light sources in place of sunlight.

However, in a plant factory, many seedlings are densely cultivated in a limited space. Therefore, depending on the arrangement of the light source, some seedlings are arranged in the shade caused by the light being blocked by the surrounding seedlings and cannot grow sufficiently.

Further, in a facility for cultivating plants using sunlight such as outdoors or in a green house, many seedlings are cultivated in a limited space, so that the same problem may occur.

In order to solve the above problem, it is conceivable to use a reflective member to condense the light emitted from the light source on the seedlings planted in the portion where the shade can be formed only by the light source.

Further, in recent years, in plant cultivation techniques, attention has been paid to the fact that light in different wavelength ranges within a wavelength range of 350 nm or more and 1100 nm or less exerts different effects. For example, light having a wavelength of 700 nm or more and 1300 nm or less has an effect of promoting germination. Light having a wavelength of 650 nm or more and 700 nm or less has the effect of promoting the elongation of seedlings. Light having a wavelength of 500 nm or more and 550 nm or less has an effect of controlling diseases and an effect of suppressing spider mites. Light having a wavelength of 380 nm or more and 450 nm or less has an effect of promoting leaf morphogenesis. Light having a wavelength of 350 nm or more and 380 nm or less has an effect of promoting flower bud formation and an effect of promoting anthocyan synthesis.

Examples of materials having high reflectance for light having a wavelength of 350 nm or more and 1100 nm or less include aluminum (Al) and silver (Ag). However, silver is not suitable as a reflective member for plant cultivation because it is very expensive and easily oxidized. Aluminum, on the other hand, is lightweight, very inexpensive, and has high corrosion resistance. Therefore, aluminum is suitable as a reflecting member for light having a wavelength of 350 nm or more and 1100 nm or less.

International Publication No. 2015/019960 (Patent Document 1) discloses an aluminum foil for a visible light reflector.

Further, Japanese Patent Application Laid-Open No. 2007-76347 (Patent Document 2) discloses a laminated structure in which films made of materials having different refractive indexes are alternately continuous as a technique for increasing the reflectance of light in a specific wavelength range. ing.

International Publication No. 2015/01/960 Japanese Unexamined Patent Publication No. 2007-76347

However, the reflectance of the aluminum foil described in International Publication No. 2015/019960 is substantially constant with respect to light of each wavelength of 350 nm or more and 1100 nm or less. On the other hand, in the laminated structure described in JP-A-2007-76347, the reflectance for light of a very limited specific wavelength is high, but the reflectance for light in a wavelength range other than that wavelength is very low.

Therefore, these conventional reflective members are not suitable for reflective members such as those for plant cultivation, which require a particularly high reflectance for each light belonging to a plurality of different wavelength ranges.

Therefore, an object of the present invention is a reflective member having a higher reflectance for each light belonging to a plurality of different wavelength ranges within a wavelength range of 350 nm or more and 1100 nm or less as compared with a conventional reflective member such as aluminum foil. To provide a manufacturing method.

The reflective member according to the present invention is formed in contact with the aluminum base material having the first surface and the first surface, and is located at a position away from the first surface in the direction intersecting the first surface. It includes a first coat layer having two surfaces and a second coat layer having a third surface formed in contact with the second surface and located away from the second surface in the intersecting direction. The surface roughness Ra of the third surface is 10 nm or less. Refractive index N1 of the first coat layer, film thickness d1 of the first coat layer, refractive index N2 of the second coat layer, film thickness d2 of the second coat layer, natural number k1 of 1 or more and 3 or less, (k1 + 1) or more (k1 + 3) ) When the following natural numbers k2, positive odd h1 less than (2 × k1), and positive odd h2 less than (2 × k2) are used, the reflective member uses the following relational expressions (1) to (4). Fulfill. (1) 0.3 <N2-N1. (2) 350 <2 × N1 × d1 + 2 × N2 × d2 <1650. (3) (h1-0.3) / (2 × k1) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h1 + 0.3) / (2 × k1). (4) (h2-0.3) / (2 × k2) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h2 + 0.3) / (2 × k2).

According to the present invention, a reflective member having a higher reflectance for each light belonging to a plurality of different wavelength ranges within a wavelength range of 350 nm or more and 1100 nm or less as compared with a conventional reflective member such as aluminum foil, and a method for manufacturing the same. Can be provided.

It is a schematic cross-sectional view which shows the reflection member which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the reflective member which concerns on this embodiment. It is schematic cross-sectional view which shows the modification of the reflection member which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the modification of the reflective member which concerns on this embodiment. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 1. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 2. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 3. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 4. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 5. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 6. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 7. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Example 8. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 1. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 2. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 3. FIG. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 4. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 5. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 6. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of Comparative Example 7. It is a graph which shows the reflectance with respect to the light of the wavelength range of 350 nm or more and 1100 nm or less of the comparative example 8.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are given the same reference number and the explanation is not repeated.
[Structure of reflective member]
The reflective member 10 according to the present embodiment will be described with reference to FIG. The reflective member 10 includes an aluminum base material 1, a first coat layer 2, and a second coat layer 3.

The aluminum base material 1 has a first surface 1A and a fourth surface 1B located on the opposite side of the first surface 1A. The material constituting the aluminum base material 1 contains aluminum (Al). The aluminum base material 1 is, for example, an aluminum foil.

The first coat layer 2 is formed in contact with the first surface 1A. The first coat layer 2 has a second surface 2A located at a position away from the first surface 1A in a direction intersecting the first surface 1A. The distance between the surface of the first coat layer 2 in contact with the first surface 1A and the second surface 2A in the direction intersecting the first surface 1A is the film thickness d1 of the first coat layer 2, which will be described later. .. The second coat layer 3 is formed in contact with the second surface 2A.

The second coat layer 3 has a third surface 3A located at a position away from the second surface 2A in a direction intersecting the second surface 2A. The distance between the surface of the second coat layer 3 in contact with the second surface 2A and the third surface 3A in the direction intersecting the first surface 1A is the film thickness d2 of the second coat layer 3, which will be described later. ..

The surface roughness Ra of the third surface 3A of the second coat layer 3 is 10 nm or less. The surface roughness Ra of the third surface 3A is a three-dimensional extension of the arithmetic mean roughness Ra defined in JIS B0601 (2001 edition) and ISO4287 (1997 edition) so that it can be applied to the observed surface. It is a value calculated by.

Further, the refractive index N1 of the first coat layer 2, the film thickness d1 of the first coat layer 2, the refractive index N2 of the second coat layer 3, and the film thickness d2 of the second coat layer 3 have the following four relational expressions. I am satisfied. Each unit of the film thickness d1 and d2 is nm.

Relational expression (1) 0.3 <N2-N1
Relational expression (2) 350 <2 × N1 × d1 + 2 × N2 × d2 <1650
Relational expression (3) (h1-0.3) / (2 × k1) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h1 + 0.3) / (2 × k1)
Relational expression (4) (h2-0.3) / (2 × k2) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h2 + 0.3) / (2 × k2)
In the relational expressions (3) and (4), k1 is a natural number of 1 or more and 3 or less. That is, k1 is 1, 2 or 3. k2 is a natural number of k1 + 1 or more and k1 + 3 or less. h1 is a positive odd number less than 2k1. h2 is a positive odd number h2 less than 2k2.

The present inventors have a plurality of different reflective members 10 in the wavelength range of 350 nm or more and 1100 nm or less as compared with the conventional reflective member which does not satisfy at least one of the above four relational expressions. It has been found that it has a high reflectance for each light belonging to the wavelength range (see Examples described later for details).

The present inventors infer the action of the constitution specified by the relational expressions (1) and (2) as follows. First, by satisfying the above relational expressions (1) and (2), the reflectance of the first wavelength λ1 and the second wavelength λ2 represented by the following relational expressions (5) and (6) is emphasized. Can be done. In the present specification, the term "emphasized" refers to light in the wavelength range including the wavelengths λ1 and λ2, for example, before and after the wavelengths λ1 and λ2, due to the interference of the reflected light on the first to third surfaces. It is used in the sense that the reflectance of the reflective member 10 with respect to light (λ1, λ2 ± 30 nm) containing any wavelength within 30 nm is higher than the reflectance of the aluminum base material 1 with respect to light in the wavelength range.

Relational expression (5) (2N1 × d1 + 2N2 × d2) / k1-50 ≦ λ1 ≦ (2N1 × d1 + 2N2 × d2) / k1 + 50
Relational expression (6) (2N1 × d1 + 2N2 × d2) / k2-50 ≦ λ2 ≦ (2N1 × d1 + 2N2 × d2) / k2 + 50
By providing the first coat layer 2 and the second coat layer 3 satisfying the relational expression (1), the reflection member 10 includes the reflected light on the third surface 3A, the reflected light on the second surface 2A, and the first surface. The effect of interference with the reflected light at 1A is enhanced. Therefore, when light of a specific wavelength is incident on the third surface 3A of the reflecting member 10, the reflected light on the third surface 3A, the reflected light on the second surface 2A, and the reflected light on the first surface 1A By strengthening each other, the reflectance for light in a specific wavelength range can be emphasized.

Further, when the first coat layer 2 and the second coat layer 3 of the reflective member 10 satisfy the relational expression (2), the first wavelength λ1 and the second wavelength represented by the relational expressions (5) and (6) are satisfied. The peak value is shown in the wavelength range where the reflectance of λ2 and λ2 for each light is 350 nm or more and 1100 nm or less.

Specifically, in the first coat layer and the second coat layer in which N1 · d1 + N2 · d2 is less than 350, as shown in FIG. 14 (FIG. 2 of Comparative Example 2), the light interference action is small and the reflectance is small. The wavelength range in which the above can be emphasized is one or less in the wavelength range of 350 nm or more and 1100 nm or less. On the other hand, in the first coat layer and the second coat layer in which N1 · d1 + N2 · d2 exceeds 1650, the light interference action becomes too large as shown in FIG. 15 (FIG. 3 of Comparative Example 3), and the reflectance becomes too large. It is impractical because the wavelength range in which it can be emphasized is too narrow.

In the first coat layer 2 and the second coat layer 3 satisfying the relational expression (2), an integer of 2N1 × d1 + 2N2 × d2 (the optical path difference between the light reflected by the third surface 3A and the light reflected by the first surface 1A). The reflectance is emphasized at a wavelength of one-third. The first wavelength λ1 satisfying the relational expression (5) and the second wavelength λ2 (λ1> λ2) satisfying the relational expression (6) have reflectances due to the first coat layer 2 and the second coat layer 3 as described above. Of the wavelengths in which is emphasized, those in the wavelength range of 350 nm or more and 1100 nm or less.

The present inventors have determined that the reflectance of the reflective member satisfying the above relational expressions (1) and (2) is N1 × d1 + N2 × d2 (the optical thickness of the first coat layer 2 and the second coat layer 3). It was discovered that it changes according to the ratio of N1 × d1 (optical film thickness of the first coat layer 2) to the sum). More specifically, the present inventors periodically respond to changes in the ratio in the range where the reflectance of the reflective member satisfying the above relational expressions (1) and (2) is more than 0 and less than 1. I found that it increased or decreased.

Further, the present inventors consider that the reflectance of the reflective member 10 satisfying the above relational expressions (1) to (4) is the reflectance of the conventional reflective member not satisfying the above relational expressions (1) to (4), particularly. It was found that the reflectance is higher than that of the reflective member that satisfies the above relational expressions (1) and (2) but does not satisfy the above relational expression (3) or (4). From a different point of view, the present inventors specify the above ratio when the reflectance of the reflective member satisfying the above relational expressions (1) and (2) shows a value higher than the reflectance of the conventional reflective member. The above relational expressions (3) and (4) are found. That is, in the present inventors, the reflective member 10 having a surface roughness Ra of the third surface 3A of 10 nm or less and satisfying the above relational expressions (1) to (4) is a reflective member such as a conventional aluminum foil. It was found that the light has a high reflectance for each light belonging to a plurality of different wavelength ranges within a wavelength range of 350 nm or more and 1100 nm or less (see Examples described later for details).

It is preferable that the reflective member 10 further has the following features.
Preferably, the purity of aluminum (Al) on the first surface 1A of the aluminum base material 1 is 99 % by mass or more. When impurities such as iron (Fe) and copper (Cu) are present in the aluminum base material 1, aluminum forms an intermetallic compound with these impurities. The intermetallic compound becomes crystal precipitates and appears on the first surface 1A, which is the surface of the aluminum base material 1, and causes irregularities on the first surface 1A. If the first surface 1A has irregularities, the light that has reached the first surface 1A is easily absorbed by the first surface 1A. Further, the crystal precipitates appearing on the first surface 1A become a factor that inhibits the reflection of light on the first surface 1A. Therefore, the larger the ratio of the crystal precipitates to the surface area of the first surface 1A, the lower the total reflectance on the first surface 1A. When the purity of aluminum on the first surface 1A of the aluminum base material 1 is less than 99% by mass, the ratio of crystal precipitates to the surface area of the first surface 1A increases, and the total reflectance on the first surface 1A decreases. do. On the other hand, when the purity of aluminum on the first surface 1A of the aluminum base material 1 is 99 % by mass or more, the ratio of the crystal precipitates to the surface area of the first surface 1A becomes very small, or the crystal precipitates are formed. Since it is not formed, the total reflectance on the first surface 1A does not decrease. Therefore, the reflecting member 10 purity aluminum is at least 99 wt% of the first surface 1A has an aluminum purity of the first surface 1A as compared with the reflecting member 10 is less than 99 wt%, the wavelength of 350nm or more 1100nm or less The total reflectance increases in the range.

Preferably, the surface roughness Ra of the first surface 1A of the aluminum base material 1 is 10 nm or less. By doing so, even when the film thickness d1 (unit: nm) of the first coat layer 2 formed so as to be in contact with the first surface 1A is thinner than 100 nm, the film thickness unevenness and omission in the first coat layer 2 The occurrence of such abnormalities can be prevented. Further, when the surface roughness Ra of the first surface 1A exceeds 10 nm, the light reaching the first surface 1A is easily absorbed by the first surface 1A. Therefore, the reflective member 10 having a surface roughness Ra of the first surface 1A of 10 nm or less has a total wavelength range of 350 nm or more and 1100 nm or less as compared with the reflective member having a surface roughness Ra of the first surface 1A of 10 nm or more. The reflectance increases.

Preferably, the refractive index N1 of the first coat layer 2 is less than 1.6. The material constituting the first coat layer 2 is composed of an acrylic resin, an ester resin, a urethane resin, a fluororesin, a silicone resin, a metal oxide, a metal fluoride, and silicon dioxide (SiO ₂ ). It preferably comprises at least one selected from the group.

Preferably, the refractive index N2 of the second coat layer 3 is 1.8 or more. The material constituting such a second coat layer 3 preferably contains a metal oxide such as _{titanium dioxide (TiO 2} ) or niobium oxide (Nb ₂ O _5). The first coat layer 2 having a refractive index N1 of less than 1.6 and the second coat layer 3 having a refractive index N2 of 1.8 or more can be easily formed by coating or vapor deposition. Therefore, the reflective member 10 including the first coat layer 2 and the second coat layer 3 can satisfy the above relational expression (1) and can be easily manufactured.

The first wavelength λ1 is, for example, 150 nm or more longer than the second wavelength λ2. Preferably, the first wavelength λ1 is 200 nm or more longer than the second wavelength λ2. The reflectance of the reflecting member 10 with respect to the light of the first wavelength λ1 and the second wavelength λ2 is 90% or more. The reflectance of the reflecting member 10 to the light of the third wavelength included in the wavelength range exceeding the second wavelength λ2 and less than the first wavelength λ1 is less than the reflectance of the reflecting member 10 to the light of the first wavelength λ1 and the second wavelength λ2. Is. The reflectance of the reflecting member 10 to the light of the third wavelength is, for example, less than 90%. Preferably, the reflectance of the reflecting member 10 for each wavelength in the wavelength range including the first wavelength λ1 and the reflectance of the reflecting member 10 for each wavelength in the wavelength range including the second wavelength λ1 are 90% or more. .. In this case, the third wavelength is less than the lower limit of the wavelength range including the first wavelength λ1 and exceeds the upper limit of the wavelength range including the second wavelength λ2.
[Manufacturing method of reflective member]
As shown in FIG. 2, the method for manufacturing the reflective member 10 according to the present embodiment includes a step of preparing the aluminum base material 1 (S10), a step of forming the first coat layer 2 (S20), and a first step. 2 The step (S30) of forming the coat layer 3 is provided.

In the step (S10) of preparing the aluminum base material 1, for example, the aluminum base material 1 as an aluminum foil is prepared. In this case, this step (S10) is obtained by a step of preparing an ingot (S11), a step of homogenizing the ingot (S12), a step of hot rolling the ingot (S13), and hot rolling. It includes a step of cold-rolling the hot-rolled material (S14) and a step of cold-rolling the cold-rolled material obtained by cold-rolling as the final finish (hereinafter referred to as final finish cold-rolling) (S15). ..

First, an ingot is prepared (step (S11)). Specifically, a molten aluminum having a predetermined composition is prepared, and the ingot is cast (for example, semi-continuous casting) by solidifying the molten aluminum. Preferably, the content of metal elements such as iron (Fe), manganese (Mn), and silicon (Si) in the molten metal is such that the purity of aluminum on the surface of the aluminum base material 1 (first surface 1A) is 99 % by mass or more. It is controlled to be.

Next, the obtained ingot is homogenized and heat-treated (step (S12)). The homogenizing heat treatment is performed under the conditions that, for example, the heating temperature is 400 ° C. or higher and 630 ° C. or lower, and the heating time is 1 hour or longer and 20 hours or lower.

Next, the ingot is hot-rolled (step (S13)). By this step, a hot-rolled material having a predetermined thickness W1 can be obtained. Hot rolling may be performed once or multiple times. When a thin aluminum ingot is produced by continuous casting, the thin plate ingot may be cold-rolled without going through this step.

Next, the hot-rolled material obtained by hot rolling is cold-rolled (step (S14)). By this step, a cold-rolled material having a predetermined thickness W2 (the material to be rolled in the final finish cold rolling step (S15)) is obtained. In this step, cold rolling is performed a plurality of times, for example, with an intermediate annealing step in between. For example, first, the first cold rolling step (S14A) is performed on the hot-rolled material to form a rolled material thinner than the hot-rolled material thickness W1 and thicker than the cold-rolled material thickness W2. Next, the obtained rolled material is subjected to an intermediate annealing step (S14B). The intermediate annealing is performed under the conditions that, for example, the annealing temperature is 50 ° C. or higher and 500 ° C. or lower, and the annealing time is 1 second or longer and 20 hours or lower. Next, a second cold rolling step (S14C) is performed on the rolled material after annealing to form a cold-rolled material having a thickness of W2.

Next, the cold-rolled material is finally finished and cold-rolled (step (S15)). In this step, the material to be rolled is finally finished and cold-rolled using a rolling roll under the condition that the rolling reduction ratio is 35% or more. The rolling roll has a roll surface that comes into contact with the material to be rolled and is rolled. Of the pair of rolling rolls arranged so as to sandwich the material to be rolled, the surface roughness Ra of the roll surface of at least one of the rolling rolls is 40 nm or less. When the material to be rolled is rolled using a rolling roll having a surface roughness Ra of more than 40 nm, the obtained aluminum base material 1 has a surface roughness RzJIS in a direction perpendicular to the rolling direction of the first surface 1A of 40 nm. It becomes large, and the surface roughness Ra of the first surface 1A also exceeds 10 nm. The surface roughness Ra of the rolling roll used in the final finish cold rolling step is preferably as small as possible, more preferably 30 nm or less. Transfer streaks (not shown) of rolling rolls are formed on the first surface 1A and the fourth surface 1B along the rolling direction.

Next, the first coat layer 2 is formed so as to be in contact with the first surface 1A of the aluminum base material 1 obtained by the final finish cold rolling (step (S20)). At this time, the first coat layer 2 is formed so that the refractive index N1 and the film thickness d1 satisfy the above relational expressions (1) to (4). Preferably, the first coat layer 2 is formed so that its refractive index is less than 1.6. The method for forming the first coat layer 2 may be any method, but is selected from the methods of applying a coating agent such as spin coating, bar coating, flow coating, dip coating, and die coating. There may be at least one. Further, the method for forming the first coat layer 2 may be at least one method selected from the group such as ion plasma treatment, ion plating treatment, sputtering treatment, thin film deposition treatment, and plating treatment.

Next, the second coat layer 3 is formed so as to be in contact with the second surface 2A of the first coat layer 2 (step (S30)). At this time, the second coat layer 3 is formed so that the refractive index N2 and the film thickness d2 satisfy the above relational expressions (1) to (4). Preferably, the second coat layer 3 has a refractive index N2 of 1.8 or more.

In this way, the reflective member 10 shown in FIG. 1 can be obtained. The surface roughness Ra of the rolling roll used for the final finish cold rolling in the step (S15) is set to 40 nm or less, and the above relational expressions (1) to (4) are used in the steps (S60) and (S70). By forming the first coat layer 2 and the second coat layer 3 to be satisfactory, the surface roughness Ra of the third surface 3A of the second coat layer 3 can be set to 10 nm or less.

The reflective member 10 according to the present embodiment includes an aluminum base material 1 configured as an aluminum foil, but the present invention is not limited to this. As shown in FIG. 3, the reflective member 11 according to the modified example of the present embodiment may include an aluminum base material 1 configured as an aluminum thin film formed on the substrate 4. The substrate 4 is formed in contact with the fourth surface 1B located on the opposite side of the first surface 1A of the aluminum base material 1 as an aluminum thin film. The material constituting the substrate 4 may be the same as or different from the material constituting the aluminum base material 1, but it is preferable that the material is different. Even with such a reflective member 11, the surface roughness Ra of the third surface 3A can be set to 10 nm or less. Further, the reflective member 11 can satisfy the above relational expressions (1) to (4). Therefore, such a reflective member 11 can exert the same effect as the reflective member 10. In addition, such a reflection member 11 can be manufactured by the manufacturing method shown in FIG. First, the substrate 4 is prepared (step (S16)), and the aluminum base material 1 is formed on the prepared substrate 4 (step (S17)). The aluminum base material 1 is formed, for example, by a vapor deposition method. After that, the first coat layer 2 and the second coat layer 3 are formed by the same method as in the above steps (S20) and (S30).

The configurations of the first coat layer 2 and the second coat layer 3 of the reflection members 10 and 11 can be designed according to the wavelength range of the light to be reflected by the reflection member 10. First, the first wavelength λ1 and the second wavelength λ2 are set based on the wavelength range of the light to be reflected. Next, the refractive indexes N1 and N2 that satisfy the relational expressions (5) and (6) to which the first wavelength λ1 and the second wavelength λ2 are substituted and also satisfy the relational expressions (3) and (4). And the film thicknesses d1 and d2 are obtained. In this way, the first coat layer 2 and the second coat layer 3 can be designed.

As described below, samples of the reflective members of Examples and Comparative Examples of this embodiment were prepared. First, using the three types of aluminum A, B, and C having different aluminum purity shown in Table 1, the aluminum base material as the aluminum foil of Examples 1 to 8 and Comparative Examples 1 to 8 was prepared by the same production method. Made. Aluminum purity A is 99.99 % by mass or more, aluminum purity B is 99.40 % by mass or more, and aluminum purity C is 98.96 % by mass or more. Further, using each aluminum base material, samples of the reflective members of Examples 1 to 8 and Comparative Examples 1 to 8 shown in Table 1 were prepared.

Comparative Example 1 satisfies the above relational expressions (2) to (4), has a surface roughness Ra of the third surface of 10 nm or less, an aluminum purity of the first surface of 99 % by mass or more, and the first surface. Although the surface roughness Ra of the surface is 10 nm or less, the above relational expression (1) is not satisfied.

Comparative Examples 2 and 3 satisfy the above relational expressions (1), (3) and (4), the surface roughness Ra of the third surface is 10 nm or less, and the aluminum purity of the first surface is 99 % by mass or more. And the surface roughness Ra of the first surface is 10 nm or less, but the above relational expression (2) is not satisfied. In Comparative Example 2, (2N1 × d1 + 2N2 × d2) is 350 or less in the above relational expression (2), and in Comparative Example 3, (2N1 × d1 + 2N2 × d2) is 1650 or more in the above relational expression (2). It is a thing.

Comparative Example 4 satisfies the above relational expressions (1), (2) and (4), has a surface roughness Ra of the third surface of 10 nm or less, and an aluminum purity of the first surface of 99 % by mass or more. Moreover, although the surface roughness Ra of the first surface is 10 nm or less, the above relational expression (3) is not satisfied.

Comparative Example 5 satisfies the above relational expressions (1) to (3), has a surface roughness Ra of the third surface of 10 nm or less, an aluminum purity of the first surface of 99 % by mass or more, and the first surface. Although the surface roughness Ra of the surface is 10 nm or less, the above relational expression (4) is not satisfied.

In Comparative Example 6, it was assumed that the above relational expressions (1) to (4) were satisfied, the aluminum purity of the first surface was 99 % by mass or more, but the surface roughness Ra of the third surface was more than 10 nm. ..

In Comparative Example 7, it was assumed that the above relational expressions (1) to (4) were satisfied, the surface roughness Ra of the third surface was 10 nm or less, but the aluminum purity of the first surface was less than 99% by mass. ..

In Comparative Example 8, it was assumed that the above relational expressions (1) to (4) were satisfied, the aluminum purity of the first surface was 99 % by mass or more, but the surface roughness Ra of the first surface was more than 10 nm. ..

Specifically, aluminum ingots having the purities A to C were prepared by semi-continuous casting, and the ingots were homogenized and heat-treated in a heating furnace. Then, hot rolling was performed until the thickness became 7.0 mm or less. The obtained hot-rolled material was cold-rolled a plurality of times, and cold-rolled (including final finish cold-rolling) was performed until the thickness reached a predetermined value T. Further, after the finish cold rolling, the surface was washed by immersing it in a 1% by mass sodium hydroxide solution at 35 ° C. for 20 seconds. For each aluminum base material thus obtained, the surface roughness Ra on the first surface and the total reflectance on the first surface were measured (measurement method and the like will be described later).

The first coat layer and the second coat layer as shown in Table 1 are formed on the aluminum base material as the aluminum foil, and the reflective members of Examples 1 to 8 and Comparative Examples 1 to 8 shown in Table 1 are formed. Samples were prepared. The material constituting the first coat layer was assumed to contain an acrylic resin, a urethane resin, a metal fluoride (magnesium fluoride (MgF ₂ )), and silicon dioxide (SiO ₂ ). The material constituting the second coat layer was assumed to contain a metal oxide (TiO ₂ or Nb ₂ O ₅ ). SpinCoater MS-A150 manufactured by Mikasa Co., Ltd. was used for forming the first coat layer and the second coat layer.

First, a first coating agent to be a first coating layer is dropped onto the first surface of each aluminum base material and coated by a spin coating method, and then at a temperature of 180 ° C. or higher and 300 ° C. or lower for 1 minute or more and 10 minutes. The following was fired. The first coating agent is a mixture of a solvent, a binder, or the like with the main component of the first coating layer. As a result, a first coat layer was formed on each aluminum base material.

Next, a second coating agent to be the second coating layer is dropped onto the second surface of the first coating layer, coated by a spin coating method, and then coated at a temperature of 180 ° C. or higher and 300 ° C. or lower for 1 minute or longer. Bake for less than a minute. The second coating agent is a mixture of a solvent, a binder, or the like with the main component of the second coating layer. As a result, a second coat layer was formed on each aluminum base material and the first coat layer.

For each sample of the reflective member thus obtained, the surface roughness Ra of the third surface of the second coat layer was measured. Further, for each sample, the film thicknesses of the first coat layer and the second coat layer were measured using a film thickness meter. Furthermore, the total reflectance was measured for each sample. Hereinafter, these measurement methods will be described.
[Measuring method]
The surface roughness Ra of the first and third surfaces is measured by using a scanning probe microscope Nanopix1000 manufactured by Seiko Instruments Inc., and the surface shape by the damping method (non-contact) is measured in a rectangular field of view of 80 μm × 80 μm. rice field. With respect to the obtained observation result, the inclination of the sample was corrected by the cubic curved surface automatic inclination correction in which the curved surface was obtained and fitted by the least squares approximation, and the surface roughness Ra was measured. The surface roughness Ra is a value calculated by expanding the center line average roughness Ra defined in JIS B0601 (1982 edition) three-dimensionally so that it can be applied to the entire observed surface. The values of the surface roughness Ra of the first surface of the aluminum base material and the values of the surface roughness Ra of the third surface of the second coat layer are shown in Table 1 above.

The film thicknesses d1 and d2 and the refractive indexes N1 and N2 of the first coat layer and the second coat layer were measured by using Filmetics F20 manufactured by Vitec Holdings Co., Ltd. in the wavelength range of 350 nm or more and 1100 nm or less in the reflected light from the reflecting member. The reflectance spectrum of the above was performed by an automatic mapping method that approximates the theoretical spectrum. The accuracy of the approximate calculation, that is, the film thickness and the refractive index at which the degree of agreement between the actually measured spectrum and the theoretical spectrum is 95% or more is derived. The values of the film thickness and the refractive index of the first coat layer and the second coat layer are shown in Table 2 above.

The total reflectance of each aluminum base material and each reflective member was measured using an ultraviolet visible light near-infrared spectrophotometer (V-570 type) manufactured by Nippon Spectral Co., Ltd. The total reflectance of the integrating sphere was measured using 99010) as a reference. The total reflectance was measured in two directions, one direction (rolling direction of the aluminum base material) and the direction perpendicular to it, and the average value of the two measured values obtained was evaluated as the total reflectance. Table 1 above shows the total reflectance of each aluminum substrate measured in the wavelength range of 350 nm or more and 1100 nm or less.

On the other hand, for each reflective member, the total reflectance (average value in the above two directions) for light of each wavelength of 250 nm or more and 2000 nm or less was first determined by the above method. From the measurement results, among the wavelengths at which the total reflectance (average value) is the maximum value in the wavelength range of 350 nm or more and 1100 nm or less, two wavelengths satisfying the above relational expressions (5) and (6) are selected for each reflective member. The first wavelength λ1 and the second wavelength λ2 (λ1> λ2) were set. Table 2 above shows the total reflectances of the first wavelength λ1 and the second wavelength λ2, and the first wavelength λ1 and the second wavelength λ2.
[Evaluation results]
As shown in Table 2 and FIGS. 5 to 12, the reflective members according to Examples 1 to 8 satisfy the above relational expressions (1) to (4), and the surface roughness Ra of the third surface is Ra. Is 10 nm or less. In the reflecting members according to Examples 1 to 8, the reflectances of the first wavelength λ1 and the second wavelength λ2 different from the first wavelength λ1 were 90% or more. As shown in FIGS. 5 to 12, the total reflectance for light of the third wavelength within the wavelength range of more than the second wavelength λ2 and less than the first wavelength λ1 is less than 90% (specifically, less than 70%). rice field. The wavelength range including the first wavelength λ1 and showing a total reflectance of 90% or more was wider than the wavelength range including the second wavelength λ2 and showing a total reflectance of 90% or more. The wavelength range including the second wavelength λ2 and showing a total reflectance of 90% or more was 50 nm or more. Further, the first wavelength λ1 was 150 nm or more longer than the second wavelength λ2.

On the other hand, in Comparative Examples 1 to 8, at least one of the reflectances of two wavelengths in the wavelength range of 350 nm or more and 1100 nm or less was less than 90%. In Comparative Examples 1 to 8, two or more wavelengths having a total reflectance of 90% or more were not confirmed in the wavelength range of 350 nm or more and 1100 nm or less.

As shown in FIG. 13, in Comparative Example 1, the total reflectance at the first wavelength λ1 (676 nm) is 90% or more, but the total reflectance at the second wavelength λ2 (457 nm) is less than 90%. there were. This is because the reflective member of Comparative Example 1 does not satisfy the relational expression (1), so that the effect of interference due to the reflected light on the third surface, the reflected light on the second surface, and the reflected light on the first surface is effective. It is thought that the cause is that it is not sufficiently raised.

As shown in FIG. 14, in Comparative Example 2, the total reflectance at the first wavelength λ1 (636 nm) is 90% or more, but 350 nm or more and less than the first wavelength λ1 and the first wavelength λ1 or more and 1100 nm or less. The total reflectance at each wavelength was less than 90%. This is because, as described above, the reflective member of Comparative Example 2 does not satisfy the relational expression (2), so that the light interference effect is small, and the wavelength range in which the reflectance can be emphasized is within the wavelength range of 350 nm or more and 1100 nm or less. It is considered to be one or less.

As shown in FIG. 15, in Comparative Example 3, the total reflectance at the first wavelength λ1 (1132 nm) is 90% or more, but the total reflectance at each wavelength of 350 nm or more and 1100 nm or less is less than 90%. there were. This is because, as described above, the reflective member of Comparative Example 3 does not satisfy the relational expression (2), so that the light interference effect becomes too large, and there are many peaks having a low height and a narrow width in the total reflectance spectrum. Since it is formed, it is considered that no wavelength range in which the reflectance can be sufficiently emphasized is formed in the wavelength range of 350 nm or more and 1100 nm or less.

As shown in FIG. 16, in Comparative Example 4, the total reflectance at the second wavelength λ2 (457 nm) is 90% or more, but 350 nm or more and less than the second wavelength λ2 and the second wavelength λ2 or more and 1100 nm or less. The total reflectance at each wavelength was less than 90%. It is considered that the reflectance of the reflective member of Comparative Example 4 could not be sufficiently emphasized on the long wavelength side in the wavelength range of 350 nm or more and 1100 nm or less because the relational expression (3) was not satisfied.

As shown in FIG. 17, in Comparative Example 5, the total reflectance at the first wavelength λ1 (633 nm) is 90% or more, but the total reflectance at the second wavelength λ2 (475 nm) is less than 90%. there were. It is considered that the reflectance of the reflective member of Comparative Example 5 could not be sufficiently emphasized on the short wavelength side in the wavelength range of 350 nm or more and 1100 nm or less because the relational expression (4) was not satisfied.

As shown in FIG. 18, in Comparative Example 6, the total reflectance at each wavelength of 350 nm or more and 1100 nm or less was less than 90%. This is because, in the reflective member of Comparative Example 6, since the surface roughness Ra of the third surface exceeds 10 nm, the light incident on the third surface is diffusely reflected, the interference effect of the light becomes small, and 350 nm or more. It is considered that the reflectance could not be sufficiently emphasized in the wavelength range of 1100 nm or less.

As shown in FIG. 19, in Comparative Example 7, the total reflectance at the first wavelength λ1 (687 nm) is 90% or more, but 350 nm or more and less than the first wavelength λ1 and the first wavelength λ1 or more and 1100 nm or less. The total reflectance at each wavelength was less than 90%. This is because, in the reflective member of Comparative Example 7, since the purity of aluminum on the first surface is less than 99% by mass , a relatively large amount of crystallization appears on the first surface, and the first surface is caused by the crystallization. It is considered that the reflection of light on the surface 1A was inhibited.

As shown in FIG. 20, in Comparative Example 8, the total reflectance at the first wavelength λ1 (687 nm) is 90% or more, but 350 nm or more and less than the first wavelength λ1 and the first wavelength λ1 or more and 1100 nm or less. The total reflectance at each wavelength was less than 90%. This is because, in the reflective member of Comparative Example 8, since the surface roughness Ra of the first surface exceeds 10 nm, the light incident on the first surface is diffusely reflected, the interference effect of the light becomes small, and 350 nm or more. It is considered that the reflectance could not be sufficiently emphasized in the wavelength range of 1100 nm or less.

From the above results, it was confirmed that the present embodiment can provide a reflective member in which the reflectance is emphasized in a plurality of wavelength ranges, which has not been realized in the past.

It should be considered that the embodiments and examples disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is not shown in the above embodiments and examples, but is indicated by the scope of claims, and is intended to include all modifications and modifications within the meaning and scope equivalent to the scope of claims. ..

1 Aluminum base material, 1A 1st surface, 1B 4th surface, 2 1st coat layer, 2A 2nd surface, 3rd coat layer, 3A 3rd surface, 4 substrate, 10, 11 reflective members.

Claims (10)

An aluminum base material having a first surface and
A first coat layer having a second surface formed in contact with the first surface and at a position away from the first surface in a direction intersecting with the first surface.
A second coat layer formed in contact with the second surface and having a third surface at a position away from the second surface in the intersecting direction is provided.
The surface roughness Ra of the third surface is 10 nm or less, and the surface roughness Ra is 10 nm or less.
The refractive index N1 of the first coat layer, the film thickness d1 of the first coat layer, the refractive index N2 of the second coat layer, the film thickness d2 of the second coat layer, a natural number k1 of 1 or more and 3 or less, (k1 + 1). ) Or more and less than (k1 + 3), a positive odd number h1 less than (2 × k1), and a positive odd number h2 less than (2 × k2), the following relational expressions (1) to (4) A reflective member that meets the requirements.
(1) 0.3 <N2-N1
(2) 658 <2 x N1 x d1 + 2 x N2 x d2 <1650
(3) (h1-0.3) / (2 × k1) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h1 + 0.3) / (2 × k1)
(4) (h2-0.3) / (2 × k2) ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ (h2 + 0.3) / (2 × k2) The reflective member according to claim 1, further satisfying the following relational expression (5).
(5) 0.78 ≦ N1 × d1 / (N1 × d1 + N2 × d2) ≦ 0.82 The reflective member according to any one of claims 1 to 2, wherein the aluminum purity of the aluminum base material is 99% by mass or more. The reflective member according to any one of claims 1 to 3, wherein the surface roughness Ra of the first surface of the aluminum base material is 10 nm or less. The refractive index N1 of the first coat layer is less than 1.6, and the refractive index N1 is less than 1.6.
The material constituting the first coat layer is at least one selected from the group consisting of an acrylic resin, an ester resin, a urethane resin, a fluororesin, a silicone resin, a metal oxide, a metal fluoride, and silicon dioxide. The reflective member according to any one of claims 1 to 4, which comprises one. The refractive index N2 of the second coat layer is 1.8 or more, and the refractive index N2 is 1.8 or more.
The reflective member according to any one of claims 1 to 5, wherein the material constituting the second coat layer contains a metal oxide. The reflective member according to any one of claims 1 to 6, wherein the aluminum base material contains an aluminum foil. A substrate made of a material different from the material constituting the aluminum base material is further provided.
The reflective member according to any one of claims 1 to 7, wherein the aluminum base material is formed on the substrate. The reflective member according to any one of claims 1 to 8, wherein the third surface is exposed. The method for manufacturing a reflective member according to any one of claims 1 to 9.
A step of forming the aluminum base material having the first surface having a surface roughness Ra of 10 nm or less by rolling or thin film deposition.
A method for manufacturing a reflective member, comprising a step of forming the first coat layer and the second coat layer on the first surface of the aluminum base material.

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