Film-coated light-transmitting substrate

Abstract

To provide a translucent substrate with a film that combines light transmission, light diffusion, and opacity. [Solution] A translucent substrate and a film on the surface of the translucent substrate are provided, wherein the film contains first silicon oxide particles having an average particle size greater than 2 μm and second silicon oxide particles having an average particle size of 0.3 μm or more and 1.0 μm or less, and the surface has a first region and a second region, the first silicon oxide particles are present in the film on the first region, the first silicon oxide particles are not present in the film on the second region, and the second silicon oxide particles are present in at least a part of the second region, thus providing a translucent substrate with a film.

Description

Technical Field

[0001] The present invention relates to a light-transmissive substrate with a film, particularly a light-transmissive substrate with a film having light-transmitting properties, light-diffusing properties, and opacity.

Background Art

[0002] Techniques for forming a film containing particles on a glass plate to impart light-diffusing properties to the glass plate are known. For example, Patent Document 1 discloses greenhouse glass in which a film containing silicon oxide particles and titanium oxide particles is formed on a glass plate. Examples 1 to 6 of Patent Document 1 disclose a film containing first silicon oxide particles having an average particle size of 3.5 μm, second silicon oxide particles having an average particle size of 0.1 μm, titanium oxide particles having an average particle size of 10 nm, and a binder. The haze of the glass plates with the film of Examples 1 to 6 is 41.6 to 62.9%. Examples 7 to 8 of Patent Document 1 disclose a film similar to that of Examples 1 to 6 except that the average particle size of the first silicon oxide particles is 0.9 μm. The haze of the glass plates with the film of Examples 7 to 8 is 49.6 to 74.2%.

[0003] The glass plate with the film of Patent Document 1 enables light to be introduced into the greenhouse while avoiding the appearance of hot spots where light is concentrated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the study by the present inventor, the glass plate with the film of Patent Document 1 has room for improvement from the viewpoint of opacity. An object of the present invention is to provide a light-transmissive substrate with a film having light-transmitting properties, light-diffusing properties, and opacity.

Means for Solving the Problems

[0006] The present invention Translucent substrate and The light-transmitting substrate comprises a film on the surface of the light-transmitting substrate, The film comprises first silicon oxide particles having an average particle size greater than 2 μm, and second silicon oxide particles having an average particle size of 0.3 μm or more and 1.0 μm or less. The surface has a first region and a second region, The film on the first region contains the first silicon oxide particles, The film on the second region does not contain the first silicon oxide particles. The second silicon oxide particles are present in at least a portion of the second region. We provide a translucent substrate with a film coating. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a translucent substrate with a film that combines light transmission, light diffusion, and opacity. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing an example of a film-coated translucent substrate according to the present invention. [Figure 2] This is a cross-sectional view showing another example of a film-coated translucent substrate according to the present invention. [Figure 3] This is a cross-sectional view showing yet another example of a film-coated translucent substrate according to the present invention. [Figure 4] This is a schematic cross-sectional view illustrating Clarity C. [Figure 5] This figure shows the film surface of the translucent substrate with a film coating from Example 1 as observed using a scanning electron microscope (SEM). [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The following description is an example of the present invention, and the present invention is not limited to the following embodiments. For example, the particle distribution shown in Figures 1 to 3 is merely one example of an embodiment of the present invention. Furthermore, the upper and lower limits of the numerical ranges below can be arbitrarily combined.

[0010] As shown in Figure 1, the film-coated translucent substrate 1 according to this embodiment comprises a translucent substrate 10 and a film 20 on the surface of the translucent substrate 10.

[0011] The translucent substrate 10 may be plate-shaped. In this case, the surface on which the film 20 is formed may be the main surface of the plate-shaped substrate. The plate-shaped substrate has two main surfaces 11 and 12, which are connected by their sides and are parallel to each other. In Figure 1, the film 20 is formed on the first main surface 11 of the translucent substrate 10. Incident light, for example, enters on the second main surface 12 side and exits from the first main surface 11 side.

[0012] The film 20 contains first silicon oxide particles 21 and second silicon oxide particles 22. The average particle size of the first silicon oxide particles 21 is greater than 2 μm, and the average particle size of the second silicon oxide particles 22 is between 0.3 μm and 1.0 μm. The film 20 may further contain third silicon oxide particles 23. The film 20 may further contain a binder 25.

[0013] The first main surface 11 has a first region 31 in which first silicon oxide particles 21 are present in the film 20, and a second region 32 in which first silicon oxide particles 21 are not present in the film 20, with second silicon oxide particles 22 present in at least a portion of the second region 32. On the surface of the film 20, protrusions 71 originating from the first silicon oxide particles 21 appear in the first region 31. The first region 31 and the second region 32 can be determined by observation from a direction perpendicular to the first main surface 11.

[0014] The light-transmissive substrate 10 may include a glass plate or a resin plate. There are no particular restrictions on the types of glass and resin. The glass plate is, for example, float glass or patterned glass. The glass plate may be tempered glass. The tempering process may be either thermal tempering or chemical tempering. The thermal tempering process may be carried out after forming the film 20.

[0015] As shown in FIG. 2, the light-transmissive substrate 10 may include a film 41 on the side of the first main surface 11. The film 41 functions as an undercoat film, and its surface becomes the first main surface 11. As shown in FIG. 3, the light-transmissive substrate 10 may include a film 42 on the side of the second main surface 12 opposite to the first main surface 11. The films 41 and 42 may be single-layer or multi-layer. The films 41 and 42 may be ultraviolet-blocking, infrared-blocking, visible light reflectance controlling, or other optical functional films. The film 42 may exhibit functions such as anti-fogging and water repellency.

[0016] The average particle size of the first silicon oxide particles is greater than 2 μm. The average particle size of the first silicon oxide particles may be 2.2 μm or more, 2.4 μm or more, 2.5 μm or more, 2.7 μm or more, 2.8 μm or more. The average particle size of the first silicon oxide particles may be 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less. The first silicon oxide particles function to significantly scatter incident light.

[0017] The average particle size of the second silicon oxide particles is 0.3 μm or more and 1.0 μm or less. The average particle size of the second silicon oxide particles may be 0.4 μm or more, 0.6 μm or more, 0.8 μm or more. The average particle size of the second silicon oxide particles may be 0.95 μm or less, 0.9 μm or less. The second silicon oxide particles also have the function of scattering incident light. However, compared with the first silicon oxide particles, its light scattering function is limited. On the other hand, the second silicon oxide particles are superior to the first silicon oxide particles in terms of the function of maintaining light transmission.

[0018] Surprisingly, the combination of the first silicon oxide particles and the second silicon oxide particles is suitable for achieving both light diffusibility and opacity while maintaining translucency. This combination can contribute to the coexistence of high-level light diffusibility and opacity, in other words, the coexistence of high haze and low clarity, especially the achievement of low clarity.

[0019] The average particle size of the third silicon oxide particles is 0.01 μm or more and 0.2 μm or less. The average particle size of the third silicon oxide particles may be 0.05 μm or more, 0.07 μm or more, or 0.1 μm or more. The average particle size of the third silicon oxide particles may be 0.18 μm or less or 0.15 μm or less. The third silicon oxide particles contribute little to the scattering of incident light but can function to improve light transmission.

[0020] In this specification, the "average particle size" may be the particle size (d50) corresponding to 50% volume cumulative obtained from the particle size distribution measured on a volume basis by the laser diffraction scattering method. Note that the average particle size means the average particle size of primary particles, that is, the particle size measured in a state where the particles are not aggregated.

[0021] The shapes of the first silicon oxide particles, the second silicon oxide particles, and the third silicon oxide particles are not particularly limited and may be fibrous, scaly, spherical, or others. The first silicon oxide particles, the second silicon oxide particles, and the third silicon oxide particles may each be spherical. In this specification, "spherical" does not mean a strict sphere but means that when observing the fine particles with a scanning electron microscope (SEM), the ratio of the maximum diameter to the minimum diameter (maximum diameter / minimum diameter) is 1.0 to 2.0, particularly 1.0 to 1.5. Spherical silicon oxide particles are mass-produced at low cost and are easily available from the viewpoints of quantity, quality, and cost.

[0022] Referring again to Figure 1, the arrangement of each silicon oxide particle will be explained. The surface of the translucent substrate 10 has a first region 31 in the film 20 where first silicon oxide particles 21 are present, and a second region 32 in the film 20 where first silicon oxide particles 21 are not present. Second silicon oxide particles 22 are present in at least a portion of the second region 32. In the first region 31 and the second region 32, the first silicon oxide particles 21 and the second silicon oxide particles 22 exert effects such as scattering on incident light. As illustrated in Figure 1, some of the second silicon oxide particles 22 may be present in the first region 31. Second silicon oxide particles 22 may not be present in a portion of the second region 32. Third silicon oxide particles 23 may be present in the first region 31 or in the second region 32.

[0023] The number N1 of first silicon oxide particles 21 present on a line segment of length 50 μm set on the surface of the film-coated translucent substrate, specifically on the first main surface 11, may be between 3 and 20. The number N1 may be between 5 and 7, between 18 and 15, or even between 12 and 18.

[0024] On the surface of the translucent substrate with a film, specifically on the first main surface 11, along a line segment of length 50 μm, the ratio TL1 / (TL1+TL2), calculated from the total length TL1 of the first region 31 and the total length TL2 of the second region 32, may be between 0.1 and 0.9. The ratio TL1 / (TL1+TL2) may be between 0.2 and 0.4, or between 0.8 and 0.6.

[0025] The number N1 and the ratio TL1 / (TL1+TL2) can be determined by observing the surface of the film 20 at at least 10 locations over a length of 50 μm and taking a simple average of the measured values.

[0026] It is desirable that the first silicon oxide particles 21 exist without overlapping in the thickness direction of the film 20. However, the second silicon oxide particles 22 and the third silicon oxide particles 23 may overlap with the first silicon oxide particles 21, or with each other, in the thickness direction of the film 20. As shown in Figure 1, the first silicon oxide particles 21 may be in contact with each other in the direction along the first main surface 11.

[0027] The maximum thickness Tmax of the film 20 may be less than twice the average particle size of the first silicon oxide particles 21, and even less than or equal to 1.5 times. The maximum thickness Tmax may be less than 8 μm. The maximum thickness Tmax may be between 2 μm and 7.5 μm. The maximum thickness Tmax may be 3 μm or more, 4 μm or more, 7 μm or less, or 6 μm or less. Achieving light diffusion and opacity with a film 20 that is not too thick has advantages for mass production.

[0028] The binder 25 has the function of holding silicon oxide particles in the film. The binder 25 may contain oxides, specifically at least one selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, niobium oxide, and tantalum oxide, and further at least one selected from the group consisting of silicon oxide and zirconium oxide, in particular silicon oxide. The binder 25 may also consist only of silicon oxide. The oxides constituting the binder 25 can be introduced into the film 20, for example, by the so-called sol-gel method.

[0029] Next, the ratios of each silicon oxide particle and binder in film 20 will be described. All numerical values ​​describing the ratios and proportions below are based on mass. The ratio R1 of first silicon oxide particles 21 to second silicon oxide particles 22 is, for example, 0.1 or more and 4 or less. The ratio R1 may also be 0.5 or more, 0.7 or more, 0.9 or more, 1 or more, or 3 or less, 2.5 or less, 2.3 or less, or 2.1 or less. The ratio R3 of silicon tertiary oxide particles 23 to silicon tertiary oxide particles 22 is, for example, 0.1 or more and less than 7. The ratio R3 may also be 0.5 or more, 1 or more, 1.2 or more, 5 or less, or 4 or less. The ratio RB of binder 25 to the total amount of total silicon oxide particles 21, 22, and 23 and binder 25 is, for example, 5% or more and 40% or less. The ratio RB may also be 10% or more, 13% or more, 15% or more, or 35% or less, 30% or less, or 25% or less.

[0030] The film 20 may contain other components besides silicon oxide particles and binders. An example of other components is oxide particles other than silicon oxide particles. Examples of oxide particles other than silicon oxide particles include titanium oxide particles and zirconium oxide particles. The oxide particles may be composite oxide particles or multilayer particles having a core-shell structure. The film 20 does not have to contain titanium oxide particles. The film 20 does not have to contain oxide particles other than silicon oxide particles.

[0031] The optical properties that can be achieved with the film-coated translucent substrate of this embodiment are as follows. A film-coated translucent substrate may have a total light transmittance Tt of 70% or more. A film-coated translucent substrate may have a total light transmittance Tt of 73% or more, and even more specifically, 75% or more. A film-coated translucent substrate may have a haze Hz of 75% or more. A film-coated translucent substrate may have a haze Hz of 78% or more, 80% or more, 85% or more, 87% or more, and even 90% or more. The film-coated translucent substrate may have a clarity C of 40% or less, 35% or less, 30% or less, and even 25% or less in some cases. The lower limit of clarity C is not particularly limited, but may be 3% or more.

[0032] As shown in Figure 4, the haze Hz is calculated by Td / Tt, and the clarity C is calculated by (Tp-Tn) / (Tp+Tn)×100%. Tt is the total light transmittance, Td is the total diffuse light transmittance, Tp is the parallel light transmittance, and Tn is the narrow-angle diffuse light transmittance. Tn is measured within a range of ±2.5° for the emission angle (see Figure 4θ). The smaller the clarity C value, the higher the opacity of the sample S. The total light transmittance Tt, haze Hz, and clarity C can be measured using, for example, a haze-gard i manufactured by BYK. These characteristics are specified in ISO 13468, 14782, and ASTM D1003, D1004.

[0033] In the translucent substrate with a film of this embodiment, the surface shape of the protrusions 71 may have a surface roughness indicated by the following index. The film-coated translucent substrate may have an RSm of 12 μm or more. The film-coated translucent substrate may have an Rk of 1.2 μm or more, and moreover, 1.5 μm or more.

[0034] Here, RSm is the average length Xs of the contour curve elements at the reference length. Rk is one of the plateau structure surface parameters and is a value that indicates the level difference of the core. RSm is specified in Japanese Industrial Standard (JIS) B0601-2001, and Rk is specified in JIS B0671-2002.

[0035] The coating solution according to this embodiment contains first silicon oxide particles and second silicon oxide particles. The coating solution may further contain third silicon oxide particles. The ratio of these particles is as described above. The coating solution may contain a binder precursor for supplying a binder to the film. The binder precursor is, for example, a hydrolyzable metal compound, typically a metal alkoxide represented by silicon alkoxide. The coating solution may contain a catalyst involved in the hydrolysis of the binder precursor, such as an acid catalyst. The acid catalyst is suitable to be a volatile inorganic acid such as hydrochloric acid or nitric acid, but is not limited to these, and may also be other inorganic acids or organic acids. The coating solution may be a dispersion in which the binder precursor is dissolved and the silicon oxide particles described above are dispersed. Various organic solvents can be used as the liquid component of the coating solution that functions as a solvent and dispersion medium. The organic solvent is preferably a solvent that is miscible with water. The organic solvent is preferably a low-boiling point solvent with a boiling point of 150°C or less, particularly between 70°C and 150°C. The organic solvent may include high-boiling point solvents with a boiling point exceeding 150°C, particularly those with a boiling point between 150°C and 200°C. It is desirable that the organic solvent include both low-boiling point and high-boiling point solvents.

[0036] In the manufacturing method according to this embodiment, the method of applying the coating solution is not particularly limited, and methods such as spin coating, roll coating, bar coating, dip coating, and spray coating can be used. A film is formed on the translucent substrate by heating the translucent substrate to which the coating solution has been applied. The heating is carried out, for example, so that the maximum temperature of the translucent substrate is between 120°C and 250°C.

[0037] As described above, this specification discloses the following technologies. The first technology is, Translucent substrate and The light-transmitting substrate comprises a film on the surface of the light-transmitting substrate, The film comprises first silicon oxide particles having an average particle size greater than 2 μm, and second silicon oxide particles having an average particle size of 0.3 μm or more and 0.8 μm or less. The surface has a first region and a second region, The film on the first region contains the first silicon oxide particles, The film on the second region does not contain the first silicon oxide particles. The second silicon oxide particles are present in at least a portion of the second region. We provide a translucent substrate with a film coating.

[0038] The second technology is, The first film-coated translucent substrate of the first technology is characterized in that the number N1 of the first silicon oxide particles present on a line segment of length 50 μm on the surface of the film-coated translucent substrate is 3 or more and 20 or less.

[0039] The third technology is, The film-coated translucent substrate of the first or second technology is wherein the maximum film thickness Tmax of the aforementioned film is less than 8 μm.

[0040] The fourth technology is, A translucent substrate with a film of any one of the first to third technologies, wherein the mass-based ratio R1 of the first silicon oxide particles to the second silicon oxide particles is 0.1 or more and 4 or less.

[0041] The fifth technology is, The film is a translucent substrate with a film of any one of the first to fourth technologies, further comprising third silicon oxide particles having an average particle size of 0.01 μm or more and 0.2 μm or less.

[0042] The sixth technology is, The fifth technology is a film-coated translucent substrate, wherein the mass-based ratio R3 of the third silicon oxide particles to the second silicon oxide particles is 0.1 or more and less than 7.

[0043] The seventh technology is, A translucent substrate with a film of any one of the first to sixth technologies, having a clarity C of 40% or less.

[0044] The eighth technology is, The seventh technology is a translucent substrate with a film, having a total light transmittance Tt of 70% or more and a haze Hz of 75% or more.

[0045] The present invention will be described in more detail below with reference to examples. (Example 1) Commercially available propylene glycol monomethyl ether, tetraethoxysilane, purified water, dispersions of silicon oxide particles (average particle size 3.2 μm), silicon oxide particles (average particle size 0.8 μm), silicon oxide particles (average particle size 0.075 μm), and binder converted to SiO2 were weighed into a glass container to obtain a high-concentration solution. The mixture consisted of commercially available propylene glycol monomethyl ether, tetraethoxysilane, purified water, dispersions of silicon oxide particles (average particle size 3.2 μm), silicon oxide particles (average particle size 0.8 μm), and silicon oxide particles (average particle size 0.075 μm), with a solid content concentration of 12%. This glass container was stirred in an oven maintained at 40°C for 8 hours.

[0046] A coating solution was obtained by stirring and mixing 6.25 g of the aforementioned high-concentration solution, 3.23 g of propylene glycol monomethyl ether, 6.25 g of propylene glycol, 0.12 g of zirconium compound (concentration of 25 wt% as ZrO2), and 0.02 g of surfactant (Shin-Etsu Silicone Co., Ltd., KP-341, diluted to 10 wt% with propylene glycol monomethyl ether). The solid content concentration in the coating solution was 7.8%. The solid content concentration relative to the entire coating solution in Example 1 was 7.8% by mass. In the solid content of the coating solution in Example 1, 23.1% by mass of first silicon oxide fine particles were present, 23.1% by mass of second silicon oxide fine particles were present, 30.8% by mass of third silicon oxide fine particles were present, 19.2% by mass of tetraethoxysilane converted to SiO2 was present, and 3.8% by mass of zirconium compound converted to ZrO2 was present. The mass of solids in the coating solution is defined as the sum of the mass of tetraethoxysilane (the source of silicon oxide in the binder) converted to SiO2, the mass of solids in the first silicon oxide fine particle dispersion, the mass of solids in the second silicon oxide fine particle dispersion, the mass of solids in the third silicon oxide fine particle dispersion, and the mass of any optionally added zirconium compound converted to ZrO2.

[0047] The coating solution was applied to the surface of a cleaned glass plate (100 x 100 mm; 3 mm thick; float glass) by spin coating. The coating solution was continuously stirred until immediately before application. The glass plate coated with the solution was dried in an oven set to 200°C to obtain a film-coated translucent substrate according to Example 1.

[0048] The optical properties (total light transmittance Tt, haze Hz, and clarity C) of the film-coated translucent substrate obtained in this manner were measured using the haze guard i described above. The optical properties were measured with the surface of the translucent substrate without the film as the incident surface of light. The results are shown in Table 1.

[0049] (Examples 2-6, Comparative Examples 1-5) As shown in Tables 1 and 2, coated glass plates were prepared in the same manner as in Example 1, except that the mixing ratio of each silicon oxide particle and binder was changed, and their optical properties were measured. However, in Examples 3 to 5, the coating solution was applied by spray coating. The coated glass plates were dried using a hot air dryer or IR heater under conditions that the glass surface temperature reached 150°C.

[0050] [Table 1]

[0051] [Table 2]

[0052] In each example containing silicon primordial particles (average particle size 3 μm) and silicon tertiary particles (average particle size 0.6 μm), a clarity C of 40% or less was achieved while maintaining high total light transmittance Tt and haze Hz. In particular, in Examples 1 to 5, where the mass-based ratio R1 of silicon primordial particles to silicon tertiary particles was 0.1 or more and 4 or less, a clarity C of 20% or less was achieved. In contrast, in each comparative example that did not contain silicon primordial or silicon tertiary particles, the clarity C exceeded 40%. The effect of the content of silicon tertiary particles (average particle size 0.075 μm) on the haze rate was very limited.

[0053] The surface shape of the films in each example and comparative example was measured using a Lasertec OPTELICS hybrid laser microscope. A 100x objective lens was used for the measurements. In Example 1, the RSm of the film-coated glass plate was 12.09 μm and the Rk was 1.601 μm. In Examples 2 to 5, the RSm was 12 μm or greater and the Rk was 1.2 μm or greater. In contrast, in Comparative Example 1, the RSm was 11.21 μm, and in Comparative Example 3, the RSm was 9.98 μm and the Rk was 0.762 μm.

[0054] Using a Hitachi High-Tech SU8220 field emission scanning electron microscope, the above-mentioned number N1 and ratio TL1 / (TL1+TL2) were measured. The number N1 was in the range of 3 to 11. The ratio TL1 / (TL1+TL2) was in the range of 0.1 to 0.7. In addition, the maximum film thickness Tmax of each example was in the range of 2 μm to 7.5 μm.

Claims

1. Translucent substrate and The light-transmitting substrate comprises a film on the surface of the light-transmitting substrate, The film comprises first silicon oxide particles having an average particle size greater than 2 μm, and second silicon oxide particles having an average particle size of 0.3 μm or more and 1.0 μm or less. The surface has a first region and a second region, The film on the first region contains the first silicon oxide particles, The film on the second region does not contain the first silicon oxide particles. The second silicon oxide particles are present in at least a portion of the second region. Translucent base material with membrane.

2. The film-coated translucent substrate according to claim 1, wherein the number N1 of the first silicon oxide particles present on a line segment of length 50 μm on the surface of the film-coated translucent substrate is 3 or more and 20 or less.

3. The translucent substrate with a film according to claim 1, wherein the maximum film thickness Tmax of the film is less than 8 μm.

4. The film-coated translucent substrate according to claim 1, wherein the mass-based ratio R1 of the first silicon oxide particles to the second silicon oxide particles is 0.1 or more and 4 or less.

5. The film-coated translucent substrate according to claim 1, wherein the film further comprises third silicon oxide particles having an average particle size of 0.01 μm or more and 0.2 μm or less.

6. The translucent substrate with a film according to claim 5, wherein the mass-based ratio R3 of the third silicon oxide particles to the second silicon oxide particles is 0.1 or more and less than 7.

7. A translucent substrate with a film according to claim 1, having a clarity C of 40% or less. Here, the clarity C is a ratio calculated by [(Tp - Tn) / (Tp + Tn)] × 100 (%), where Tn is the narrow-angle diffuse light transmittance measured within a range of ±2.5° for the emission angle θ, and Tp is the parallel light transmittance.

8. A translucent substrate with a film according to claim 7, having a total light transmittance Tt of 70% or more and a haze Hz of 75% or more.

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