Heat insulation material made of inorganic material, material set for manufacturing the heat insulation material, material for underlayer, and manufacturing method
阅读说明：本技术 无机材料制成的隔热件、用于制造该隔热件的材料组、底层用材料以及制造方法 (Heat insulation material made of inorganic material, material set for manufacturing the heat insulation material, material for underlayer, and manufacturing method ) 是由 川野顺一 小林雄一 于 2020-11-17 设计创作，主要内容包括：提供一种新型的无机材料制成的隔热件。是具备基材、层叠于该基材上的底层、以及层叠于该底层上的顶层而成的无机材料制成的隔热件,其中,顶层具有无法视觉辨认到底层的厚度,且使红外线透过,底层具备该底层的材料与顶层的材料的混合以及不存在顶层的材料的主反射区域。通过顶层与底层的适当组合,即使在40以下的L*的情况下也可得到超过30％的高日照反射率(TSR)。(A novel heat insulating member made of an inorganic material is provided. The heat insulating material is an inorganic heat insulating material comprising a base material, a bottom layer laminated on the base material, and a top layer laminated on the bottom layer, wherein the top layer has a thickness such that the bottom layer is invisible and transmits infrared rays, and the bottom layer comprises a mixture of the material of the bottom layer and the material of the top layer and has no main reflection region of the material of the top layer. By appropriate combination of the top and bottom layers, a high solar reflectance (TSR) of more than 30% can be obtained even at L ×, 40 or less.)
1. A heat insulator comprising a base material, a bottom layer laminated on the base material and having a TSR larger than that of the base material, and a top layer laminated on the bottom layer, wherein the top layer is made of an inorganic material,
the top layer has a thickness such that the bottom layer is invisible and transmits infrared rays,
the bottom layer is provided with a mixture of the material of the bottom layer and the material of the top layer and no primary reflective area of the material of the top layer.
2. A thermal insulation according to claim 1, wherein the primary reflective region has a thickness of 10 μm or more.
3. A thermal insulating material according to claim 1 or 2, wherein the halo height of the main reflective region measured by X-ray diffraction is 230cps or less.
4. A thermal insulating element according to any of claims 1 to 3,
as the material of the bottom layer, the following formula is expressed as RO: 0.1 to 0.5, R2O：0.5～0.9、B2O3：0.0～1.0、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O。
5. As the material of the top layer, expressed as RO in the seeger formula: 0.5 to 0.9, R2O：0.1～0.5、B2O3：0.0～1.0、Al2O3：0.3～1.0、SiO2：1.3～3.7、SiO2/Al2O3: 3.4 to 6.9, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O。
6. A heat insulator, comprising:
a substrate;
a bottom layer with a TSR of 80% or more; and
a top layer containing (Cr, Fe) having a Cr/Fe ratio (molar ratio) of 93 to 97: 7 to 3 or a Cr/Fe ratio (molar ratio) of 80 to 97: 20 to 3 and having a non-spinel structure2O3A solid solution, the top layer having a value of Lx of 30 or less,
the top layer has a thickness such that the bottom layer is invisible and transmits infrared rays,
the bottom layer is provided with a mixture of the material of the bottom layer and the material of the top layer and no primary reflective area of the material of the top layer.
7. A material group of thermal insulation members, which is a material group of thermal insulation members made of inorganic materials, wherein the material group includes:
a material of the top layer having a HT as measured by HMS falling within a range from a predetermined firing temperature to 100 ℃ or less of the firing temperature; and
A material of the bottom layer that does not vitrify at the firing temperature.
8. The material set according to claim 7, wherein a halo height measured by an X-ray diffraction method when the material of the underlayer is fired at the firing temperature is 230cps or less.
9. The material set according to claim 7 or 8,
as the material of the top layer, expressed as RO in the seeger formula: 0.5 to 0.9, R2O：0.1～0.5、B2O3：0.0～1.0、Al2O3：0.3～1.0、SiO2：1.3～3.7、SiO2/Al2O3: 3.4 to 6.9, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O，
As the material of the bottom layer, the following formula is expressed as RO: 0.1 to 0.5, R2O：0.5～0.9、B2O3：0.0～1.0、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O。
10. A method for manufacturing a heat insulating material made of an inorganic material, the heat insulating material comprising a base material, a bottom layer laminated on the base material and having a TSR larger than that of the base material, and a top layer laminated on the bottom layer, the top layer having a thickness such that the bottom layer is invisible and transmitting infrared rays therethrough,
sequentially laminating the material of the bottom layer and the material of the top layer on the substrate,
firing is carried out at a temperature such that the HMS measured HT of the top layer falls within 100 ℃ below this temperature.
11. The manufacturing method according to claim 10,
the firing temperature is such that the halo height of a region in the bottom layer where the material of the bottom layer does not react with the material of the top layer becomes 230cps or less.
12. A heat insulator comprising a base material, a bottom layer laminated on the base material, and a top layer laminated on the bottom layer, wherein the heat insulator is made of an inorganic material,
as the material of the bottom layer, the following formula is expressed as RO: 0.1 to 0.5, R2O：0.5～0.9、B2O3：0.0～1.0、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O and is provided with a main reflective area where no material of the top layer is present.
13. A thermal insulating element according to claim 12, wherein the material of the top layer has a HT as measured by HMS which falls within a range from a predetermined firing temperature to 100 ℃ or less of the firing temperature.
14. A thermal insulating material according to claim 12 or 13, wherein the halo height of the primary reflective region measured by X-ray diffraction is 230cps or less.
15. A material for a base layer, which is a material for a base layer of an inorganic heat insulating material, wherein the seeger number thereof is represented by the seeger formula RO: 0.1 to 0.5, R 2O：0.5～0.9、B2O3：0.0～1.0、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O, solar reflectance is 80% or more in a thickness of 100 μm.
Technical Field
The present invention relates to an improvement in a heat insulator made of an inorganic material, a material set for manufacturing the heat insulator, a material for a base layer, and a method for manufacturing the heat insulator.
Background
From the viewpoint of recent energy saving requirements, high heat insulation is required for building materials.
Among building materials, improvement in heat insulation properties is particularly required for black building materials such as roofing shingles. For example, in the japanese heat island countermeasure council, it is disclosed that black-based heat insulating glazes having an L value of 40% or less are aimed at achieving an infrared reflectance of 40% or more and a solar reflectance of 30%.
The present invention is directed to a heat insulator made of an inorganic material, but the same problem is also present in a coating material made of an organic material, and for example, patent document 1 discloses a technique related to the present invention.
Patent document 2 proposes a pigment having high heat insulating properties.
Non-patent document 1 discloses a engobe that exhibits a solar reflectance of 90% or more.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 4-246478
Patent document 2: japanese patent No. 5737523
Non-patent document
Non-patent document 1: design of ceramic tiles with high sensitivity of the variation of a functional entry, Ceramics International 39(2013),9583-
Disclosure of Invention
Problems to be solved by the invention
As the pigment disclosed in patent document 2, the inventors of the present application have proposed a pigment having a high solar reflectance (total reflectance). Namely, is composed of (Cr, Fe)2O3Made of solid solution, L*The black pigment having a value of 30 or less is a black pigment having a non-spinel structure, wherein the ratio (molar ratio) of Cr to Fe is 93 to 97: 7 to 3. The top layer using this pigment showed 45% infrared reflectance (hereinafter, sometimes abbreviated as "NIR") and 24% solar reflectance (hereinafter, sometimes abbreviated as "TSR") as well. Here, the ratio (molar ratio) of Cr to Fe may be set to 80 to 97: 20 to 3.
However, the L value of 40 or less, which is revealed by the Japanese society for thermal island countermeasures, does not satisfy the objectives of 40% or more NIR and 30% or more TSR.
Means for solving the problems
The present inventors have conducted extensive studies to achieve the above object. As a result, it was found that the glaze using the pigment exhibits relatively high NIR (═ 45%) because the pigment itself has a function of reflecting infrared rays, and the top layer containing the pigment also has a function of transmitting infrared rays. That is, incident infrared rays transmit through the top layer and are reflected by the base material supporting the top layer, and the reflected infrared rays again transmit through the top layer and are emitted to the outside.
Based on this finding, it is considered that if the light reflectance of the surface of the substrate is increased, the NIR as the top layer is increased, thereby increasing the TSR thereof.
Therefore, the surface of the substrate is covered with a material (underlayer) having a higher light reflectance than that of the substrate, and the TSR thereof is measured. The results are shown in FIG. 1. As is clear from the results of fig. 1, as the infrared reflectance NRI of the bottom layer becomes higher, the solar reflectance TSR of the entire heat insulator, that is, the composite layer of the bottom layer and the top layer becomes higher.
When the black pigment of example 1 was used, it was found that when the TSR of the underlayer was 80% or more, the solar reflectance TSR of the entire heat insulator was approximately 30% or more. The black pigment of example 1 originally had NIR of 45%, and therefore, here, satisfied the target required by the japan heat island countermeasure council.
Drawings
Fig. 1 is a graph showing the relationship between the TSR of the entire heat insulating material of the examples and comparative examples and the TSR of the bottom layer.
Fig. 2 is a schematic view showing the structure of a heat insulator according to an embodiment of the present invention.
Fig. 3 is a schematic view showing the structure of a heat insulator according to a comparative example of the present invention.
Fig. 4 is a graph showing the relationship between the underlayer and the TSR.
Fig. 5 is a melting curve of the glaze of the example.
Fig. 6 is a spectral reflectance curve of example 3.
Fig. 7 is a spectral reflectance curve of example 4.
Fig. 8 is a spectral reflectance curve of example 5.
Fig. 9 is a spectral reflectance curve of example 6.
Fig. 10 is a spectral reflectance curve of example 7.
Fig. 11 is a graph showing the relationship between TSR of the bottom layer (alone) and halo height.
Detailed Description
In the results of fig. 1, the specifications of the heat insulator of example 1 before sintering were as follows.
Base material:
materials: ceramic ware
Thickness: 5 to 20mm
Bottom layer:
materials (composition): expressed in Seger's equation, RO: 0.1 to 0.5, R2O：0.5～0.9、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O
Thickness: 100 μm
The TSR of the bottom layer is a value obtained when the bottom layer is fired alone (i.e., without stacking any top layer), and is adjusted by matching to give a change. In addition, the TSR of the substrate was 50%. That is, the horizontal axis 50% represents the case without the underlayer.
Top layer:
materials: glaze comprising black pigment (example 1: product name: 42-710A (Gexi industries))
Note) Black pigment (example 1): the ratio (molar ratio) of Cr to Fe is 93 to 97: 7 to 3 or the ratio (molar ratio) of Cr to Fe is 80 to 97: 20 to 3, and (Cr, Fe) having a non-spinel structure is used2O3Solid solution
L value of the top layer: less than 30
Firing conditions:
firing temperature: 1130 to 1150 DEG C
Retention time: 1 to 3 hours
Determination conditions for TSR:
a measuring device: ultraviolet, visible light and infrared spectrophotometer V-670 manufactured by Nippon spectral Co., Ltd
The top layer of example 2 was used as black glaze with the product name: the same conditions as in example 1 were used except that ECO BLACK (KASAI industries).
The top layer of comparative example 1 was used as a black glaze with the product name: the same conditions as in example 1 were used except that C BLACK (KASAI industries).
The top layer of comparative example 2 was used as a black glaze with the product name: the conditions were the same as in example 1 except that Black Mat (KASAI industries).
In addition, in the top layer containing the black pigment of example 2, as the TSR of the bottom layer increased, the TSR of the entire heat insulator, that is, the composite layer of the bottom layer and the top layer also increased.
On the other hand, in the top layers containing the black pigment of comparative examples 1 and 2, the change in TSR of the bottom layer hardly affects the TSR of the entire heat insulating material.
L of example 2 and comparative examples 1 and 2 is 30 or less.
As described above, the present invention can be defined as follows.
That is, a heat insulator includes:
a base member having a surface with a solar reflectance (TSR) of 80% or more; and
a top layer laminated on the surface of the base member, the top layer containing a black pigment, wherein the black pigment is a non-spinel structure (Cr, Fe) having a Cr/Fe ratio (molar ratio) of 93 to 97: 7 to 3 or a Cr/Fe ratio (molar ratio) of 80 to 97: 20 to 32O3A solid solution, and the black pigment has an L value of 30 or less.
According to the heat insulator configured in this way, The Solar Reflectance (TSR) is 30% or more. Of course, the infrared reflectance (NIR) is also 40% or more.
In view of the above, the present inventors have found that infrared rays may be transmitted through the top layer made of an inorganic material and reflected by the bottom layer. Here, the top layer is set to have a thickness such that the bottom layer is not visually recognized. This is to ensure the design as a heat insulator.
Incidentally, as described in patent document 1, there is an organic paint which transmits infrared rays. In the case of an organic coating material, an organic primer layer having a high TSR is formed, dried, and then the organic coating material is applied. At this time, the organic base layer and the coating layer are separated, and the materials of the two are not mixed or reacted.
In contrast, the heat insulator made of an inorganic material has the following problems.
The top layer is of course vitrified, whereas the bottom layer must be avoided. This is because TSR is significantly reduced if the underlayer is vitrified.
In the case of a heat insulator made of an inorganic material, a slurry of a glaze is generally laminated on a slurry of a base layer, and both are fired at the same time. At which the material of the top layer is fully vitrified. On the other hand, the material of the bottom layer is not vitrified. In other words, the material of the underlayer is in a state in which the particles constituting the underlayer are sintered, that is, in a state in which the surfaces of the particles are melted and bonded to each other.
When the bottom layer is fired alone, the entire material is uniformly sintered and the surface has a high light reflectance, but when the top layer is sintered in a state where the top layer is laminated, the material of the top layer is heated to a temperature exceeding the glass transition temperature thereof and fluidized, and penetrates between particles of the material of the bottom layer, where it reacts with the material of the bottom layer. When the sintering process is completed and cooled, the material of the top layer and the material of the bottom layer after the reaction are vitrified mixed. This vitrified mixture transmits light, and therefore a high light reflectance cannot be secured.
As a result of intensive studies by the inventors of the present invention to solve the above-described problems, it is considered that it is inevitable to mix the material of the bottom layer and the material of the top layer by reacting them with each other by firing. Further, it is considered that if the bottom layer is thickened to ensure a region into which the material of the top layer does not infiltrate even at the time of firing, sufficient light reflection can be ensured at the surface of the region.
That is, the first aspect of the present invention is defined as follows.
A heat insulator comprising a base material, a bottom layer laminated on the base material, and a top layer laminated on the bottom layer, the heat insulator being made of an inorganic material,
the top layer has a thickness such that the bottom layer is invisible and transmits infrared rays,
the bottom layer is provided with a mixture of the material of the bottom layer and the material of the top layer and no primary reflective area of the material of the top layer.
According to the first aspect of the present invention defined above, since the primary reflection region is provided on the back sheet, infrared rays transmitted through the top sheet can be reflected by the primary reflection layer. Here, it is considered that the thickness of the main reflection region substantially composed of only the material of the underlayer needs to be 10 μm or more. If the main reflective layer is smaller than 10 μm, there is a risk that the infrared rays transmitted through the top layer and mixed therewith will be transmitted through the main reflective layer. The upper limit of the layer thickness of the main reflection region is not particularly limited, but is set to 300 μm.
Fig. 2 shows the basic structure of the heat insulating material 1 of the present invention. As shown in fig. 2, if the main reflection region of the bottom layer has a sufficient thickness, the infrared rays transmitted through the top layer and the bottom layer can be reliably reflected by the main reflection region.
Thus, as shown in the embodiments of fig. 1, the light reflection characteristics (TSR) of the underlayer can be utilized.
Fig. 3 shows a heat insulating material of a comparative example in which a bottom layer is thinned. The overall thickness of the underlayer is made thinner compared to the example of fig. 2. As a result, the main reflection region becomes thin, and the infrared rays transmitted through the top layer and the bottom layer are transmitted through the main reflection region and absorbed by the substrate.
The relationship between the TSR of the undercoat layer and the TSR of the entire heat insulating material when the thickness of the undercoat layer was 30 μm (comparative example 3) for the black pigment used in example 1 of fig. 1 is shown by a broken line in fig. 1.
In comparative example 3, since the bottom layer was thin, the material of the top layer impregnated the entire area of the bottom layer, i.e., the bottom layer was entirely intermixed. As a result, the infrared rays transmitted through the top layer and the bottom layer are mainly reflected by the surface of the substrate 2.
In the example of comparative example 3, the primer layer did not exert any effect in the TSR characteristics of the heat insulator.
From the above, it is necessary for the bottom layer to have a sufficient thickness of the primary mix.
Therefore, the inventors of the present invention have made intensive studies on a method of ensuring such main mixing in the bottom layer when the top layer is laminated on the material of the bottom layer and fired.
According to the study of the present inventors, the following methods (1) to (3) can be considered.
(1) Sufficient thickness is ensured in the bottom layer itself.
FIG. 4 shows the relationship between the film thickness of the underlayer used in the above-described examples and the TSR thereof. At this time, no top layer was laminated on the bottom layer, and the bottom layer was exposed. As is clear from the relationship in FIG. 4, the film thickness of the underlayer is preferably 70 μm or more. If the film thickness is less than 70 μm, the film thickness of the underlayer becomes uneven mainly, and thus there is a possibility that infrared rays and other wavelengths of light preferentially transmit through the thin portion.
Further, when the material of the bottom layer is selected, the transmittance of infrared rays is reduced, the uniformity of the film thickness is ensured, and the density is further improved, and according to the study of the inventors of the present invention, when the thickness of 50 μm or more is ensured as the bottom layer, the thickness of 10 μm or more can be ensured in the main reflection region, which is a region other than the mixture of the material of the top layer and the material of the bottom layer, under the ordinary firing conditions of the top layer.
(2) The slurry of the top layer is stacked on the fired bottom layer, followed by firing.
If the bottom layer is fired in advance, the materials of the both hardly react even if the top layer is fired thereafter. Therefore, in this case, the entire region of the underlayer functions as the main reflection region, and therefore a sufficient thickness can be secured for the main reflection region.
(3) Relationship of Top layer to firing temperature
When the top layer of slurry is stacked on the bottom layer of slurry and fired, it is inevitable that the two materials react and mix. However, by selecting the material of the top layer, the formation of a mixture can be suppressed.
That is, if the firing temperature is determined, the glass transition temperature of the top layer is made as close to the firing temperature as possible, thereby suppressing the material of the top layer from flowing. Thereby, the material of the top layer is less likely to infiltrate into the bottom layer, thereby suppressing the formation of intermixing.
In addition, the bottom layer may be composed of a variety of materials. For example, the under layer may be made of a material having a higher reflectance on the glaze layer side or a material having a higher bondability on the base layer side.
The thickness of the top layer is not particularly limited, and may be arbitrarily selected in accordance with the design property, durability, and the like required for the top layer. In order to ensure the design of the top layer, particularly the color tone thereof, the thickness of the bottom layer therebelow is preferably not visually recognized. The thickness of the top layer can be, for example, 50 to 100 μm.
The top layer may be composed of a plurality of material layers.
The inventors of the present invention focused on the HMS measurement (measurement based on a high temperature microscope) of the material of the top layer.
Fig. 5 shows the melting curves of the glazes of examples 3 to 7.
The glazes of examples 3 to 7 have HT as follows.
Example 3: 1141 deg.C
Example 4: 1121 deg.C
Example 5: 1088 deg.C
Example 6: 1053 deg.C
Example 7: 1035 deg.C
In addition, the melting curve of fig. 5 was measured by a high temperature microscope EM301 manufactured by Hesse Instruments.
Further, HT (hemispherical temperature) was also measured by a high temperature microscope EM301 manufactured by Hesse Instruments.
HMS measurement is a method for confirming the melting behavior of a glaze by a high-temperature heating microscope method.
The temperature rise conditions are 60 ℃/min to 500 ℃, 10 ℃/min at 500-1000 ℃ and 5 ℃/min at the temperature above 1000 ℃.
HT (hemispherical temperature) is the temperature at which the height of the sample is measured to be half the base width, according to DIN51730 Bestimug des Asche-Schmelzverhaltens.
Fig. 6 to 10 and table 1 show spectral reflectance curves when the glazes of examples 3 to 7 are used, respectively. The underlayer used was a underlayer with a TSR of 80% when fired alone, and the thickness was set to 100 μm.
The spectral reflectance curve was measured by an ultraviolet-visible-light-infrared spectrophotometer V-670 manufactured by Nippon spectral Co.
From the results of fig. 6 to 10 and table 1, the temperature of HT of the top layer is preferably from the firing temperature or lower to 100 ℃ or lower, more preferably 50 ℃ or lower, more preferably equal to the firing temperature. In addition, the firing temperature in examples 3 to 7 was 1140 ℃. In examples 3 to 7, the flow-out temperature (temperature at which the fluid becomes) was 100 ℃ higher than the firing temperature.
In the case of a glaze material having an outflow temperature higher than the firing temperature by more than 100 ℃, for example, a glaze material having an outflow temperature higher than the firing temperature by 150 ℃ or more, the primary reflective layer can be secured even when HT is lower than the firing temperature by more than 100 ℃, for example, lower than the firing temperature by 150 ℃.
Of course, when the outflow temperature is close to the firing temperature, the firing cost can be suppressed.
In other words, it is preferable to use a material having a glass transition temperature substantially equal to the firing temperature as the material of the top layer, and to suppress the fluidity when heated to the firing temperature as much as possible.
TABLE 1
As the material composition of the top layer with HT falling in the range of 100 ℃ or less of the firing temperature with respect to the firing temperature of 1140 ℃, the following material composition may be employed: expressed in Seger's equation, RO: 0.5 to 0.9, R 2O：0.1～0.5、B2O3：0.0～1.0、Al2O3：0.3～1.0、SiO2：1.3～3.7、SiO2/Al2O3: 3.4 to 6.9, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O。
The following components may be contained in a range not impairing the reflectance. Examples of the component include chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, and zircon.
In the present invention, it is also understood from the results of fig. 1 that the light reflectance of the underlayer has a large influence on the TSR. Thus, the inventors of the present invention have a TSR of 80 for single firingWhen the composition of the underlayer was examined, the composition was preferably as follows. Namely, the following composition was adopted: expressed in Seger's equation, RO: 0.1 to 0.5, R2O：0.5～0.9、B2O3：0.0～1.0、Al2O3：2.2～10.2、SiO2：7.2～29.2、TiO：0.0～0.5、ZrSiO4：0.0～5.5、SiO2/Al2O3: 0.7 to 23.8, wherein RO is MgO, CaO or BaO, R2O＝Li2O、Na2O or K2O。
The following components may be contained in a range not impairing the reflectance. Examples of the component include chromium, manganese, iron, cobalt, nickel, copper, zinc, and tin.
The powder obtained by firing the material of the underlayer is subjected to X-ray diffraction, and the average value of the peak intensity in the range of 23 to 25 degrees 2 θ is calculated as the halo height. The results are shown in FIG. 11.
The X-ray diffraction apparatus which gave the results of FIG. 11 was a model D2 PHASER manufactured by Bruker.
From the results of fig. 11, it is found that in order to make the TSR of the underlayer 80% or more, it is preferable to make the halo height 230cps or less.
In general, a smaller halo height indicates less vitrification. Thus, the halo height of the main reflection region in the bottom layer is preferably 230cps or less.
The present invention is not limited to the description of the embodiment and the examples of the invention described above. Various modifications are also included in the present invention within the scope that can be easily conceived by those skilled in the art without departing from the scope of the claims.
Description of the reference numerals
2: a substrate; 3: a bottom layer; 3-1: a primary reflection region; 3-2: mixing; 5: a top layer.