DE112013006464T5 - Transparent substrate - Google Patents

Abstract

An object of the present invention is to provide a transparent substrate which can suppress light reflection, can reduce the adhesion of fingerprints and can suppress glitter. The present invention provides a transparent substrate having at least one surface having a Δglass / ΔRMS value of less than or equal to -800, the Δglancy / ΔRMS value being the amount of gloss change (%) relative to the extent of change in the Surface roughness RMS (μm) represents.

Description

TECHNICAL AREA

The present invention relates to a transparent substrate.

STATE OF THE ART

Transparent substrates are conventionally used in various display units, such. As liquid crystal displays used.

In recent years, display units such. As liquid crystal displays, widely used in mobile devices and devices for vehicles. In particular, when used in vehicle devices, sunlight or light from a vehicle lamp tends to cause light reflection and thereby affect visibility, and therefore, there has been a demand for a technique for suppressing light reflection. Further, touch screens are being used more and more frequently, and since such applications frequently involve contact with the human hand, there has been a demand for a technique for suppressing fingerprint adhesion.

There is known a method of forming minute unevenness on a glass surface as a method of adjusting the gloss level and suppressing adhesion of fingerprints and the like to a glass product.

For example, Patent Document 1 discloses a surface treatment method for a glass product which comprises immersing a glass product in an etching solution containing hydrogen fluoride, ammonium fluoride and a fine glass powder, washing the glass product with water, further immersing the glass product in an etching / polishing solution containing hydrogen fluoride, sulfuric acid and nitric acid, and then washing the glass product.

DOCUMENTS OF THE PRIOR ART

PATENT DOCUMENTS

• Patent Document 1: Japanese Laid-Open Patent Publication No. S61-36140 ,

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

However, in Patent Document 1, the use of a glass for a transparent substrate of a display device or the like is not provided, and when a glass substrate which has been subjected to a surface treatment is disposed on a surface of a liquid crystal display, depending on the relationship between the size Unevenness of the glass and the pixel or pixel size of the liquid crystal display z. B. unevenness of the light scattering (hereinafter also referred to as "glitter") occur.

The present invention has been made in view of the above-mentioned problems of the prior art and it is an object of the present invention to provide a transparent substrate which can suppress light reflection, can reduce the adhesion of fingerprints and can suppress glitter.

MEDIUM TO SOLVE THE PROBLEM

In order to solve the above-mentioned problems, the present invention provides a transparent substrate having at least one area with a Δglass / ΔRMS value of less than or equal to -800, where the Δglancy / ΔRMS value relates the amount of gloss change (%) on the extent of change in surface roughness RMS (μm).

ADVANTAGEOUS EFFECT OF THE INVENTION

A transparent substrate according to the present invention can suppress light reflection, reduce adhesion of fingerprints, and suppress unevenness of light scattering (glittering).

BRIEF DESCRIPTION OF THE DRAWINGS

1 shows a change in gloss in the change of surface roughness according to an embodiment of the present invention,

2 Fig. 10 is a laser microscope image of a transparent substrate of Experimental Example 2,

3 FIG. 10 is a laser microscope image of a transparent substrate of Experimental Example 8 and FIG

4 shows regression lines obtained in the calculation of the value ΔGlance / ΔRMS in Experiment Examples 2 and 8.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted, however, that the present invention is not limited to the embodiments described below and various variations and modifications may be made without departing from the scope of the present invention.

Hereinafter, a transparent substrate according to an embodiment of the present invention will be described.

The transparent substrate according to the present embodiment is characterized by having at least one area having a Δglass / ΔRMS value of less than or equal to -800, wherein the Δglancy / ΔRMS value is the amount of gloss change (%) in terms of the amount the change of the surface roughness RMS (μm).

As a result of conducting extensive investigations on a transparent substrate which can suppress light reflection, can reduce the adhesion of fingerprints and can suppress glitter, the inventor of the present invention has found that a solution by forming an appropriate fine concavo-convex structure the surface of the transparent substrate can be obtained, and thus has made the present invention.

First, a transparent substrate for suppressing glitter preferably has a suitable fine concavo-convex structure as described above.

A suitable fine concave-convex structure refers to a structure in which the shape of bumps, shape distribution of bumps, size of bumps and size distribution of bumps are within an appropriate range. In conventional techniques, these factors were evaluated individually to examine their correlation with a glitter. However, no clear relationship could be obtained.

The inventor has found that it can be judged whether these factors are within an appropriate range based on the amount of change in gloss (%) based on the amount of change in surface roughness RMS (μm).

The gloss (%) is an index representing the gloss level of an object surface in a one-dimensional manner by focusing on the proportion of specular reflection light and the directional distribution of diffused reflection light. The gloss (%) can be measured as a mirror gloss according to a method corresponding to the method given in JIS Z 8741. The specular gloss decreases when there is an irregular reflection and absorption at the plane of incidence, and therefore, the gloss (%) can be considered as a value which is e.g. B. reflects the shape of bumps, the shape distribution, the size of bumps and the size distribution indirectly.

On the other hand, the surface roughness RMS (μm) represents the average depth of the unevenness from a reference plane (substrate surface before surface treatment in the present embodiment). The surface roughness RMS (μm) can be measured by a method similar to that described in JIS B 0601 (2001 ). It should be noted that the surface roughness RMS (μm) may in some cases be represented as the square root mean square value Sq. With regard to the measuring method, z. For example, a measurement using a laser microscope with respect to its wide field of view may be preferable, which can reflect the reflection of a wide measuring range of the surface of the transparent substrate, although various methods generally used for measuring the surface roughness may be used.

The amount of change of gloss (%) with respect to the amount of change in surface roughness RMS (μm) refers to the amount of change in gloss (%) resulting from a slight change in surface roughness RMS (μm) by performing an etching process after forming fine unevenness on at least one surface (surface) of the transparent substrate.

Although the method of etching used in this case is not particularly limited, e.g. For example, in a case where the transparent substrate is a glass substrate, an etching process using hydrofluoric acid (an aqueous solution of hydrogen fluoride) is performed. Furthermore, a dry etching, such. As a reactive ion etching can be used.

Hereinafter, the amount of change of gloss (%) with respect to the amount of change in surface roughness RMS (μm) will be qualitatively described. The 1 Fig. 12 shows schematic cross-sectional views of fine concavo-convex structures of surfaces of a transparent substrate (hereinafter also referred to simply as "shape of the unevenness"). The solid lines in the drawing indicate the shapes of the unevenness of the surfaces of a transparent substrate before performing an etching, and the dotted lines indicate the shapes of the unevenness after the etching. The 1 (a) FIG. 14 shows an example of a preferred shape of the unevenness including fine pits according to the present embodiment, and FIG 1 (b) shows an example in which the recesses are larger than those in the 1 (a) ,

First, with regard to 1 (a) and (b) the depths of the pits in the original state before etching are different. In particular, the depth of the pits, ie, the radius of curvature of (a) in which finer pits are present, is less than the depth of the pits of (b). Then, when an etching is performed so that the surfaces with the same amount of etching in the 1 (a) and (b) are slightly etched, the change in the depth of the recesses in the 1 (a) and (b) are substantially the same, and hence the change in surface roughness RMS (μm) will be substantially the same.

On the other hand, the radius of curvature of the recesses in the 1 (a) is smaller than that of (b), and hence the shape of a convex portion corresponding to a connecting portion between the recesses after etching and A in FIG 1 (a) is compared with the shape of a convex portion after the etching indicated by B in FIG 1 (b) is shown flattened. That is, with respect to the change in the shape of the convex portion, the change in (a) is larger, and therefore, the change of gloss (%) in (a) is also larger. In this way, the absolute value of ΔGlanz / ΔRMS increases as the size of the recess becomes smaller.

Thus, by evaluating the degree of change in gloss (%) with respect to the amount of change in surface roughness RMS (μm), a judgment can be made as to whether a surface has a suitable fine concavo-convex structure as described above.

It should be noted that the 1 shows a case where the shapes of the bumps are uniform. In cases where the shape of the bumps is not uniform or when larger pits are included, a portion having a larger radius of curvature such as that of FIG 1 (b) , so that the amount of change of gloss (%) based on the amount of change in surface roughness RMS (μm) may be smaller than in the case of 1 (b) , Thus, by evaluating the degree of change in gloss (%) with respect to the amount of change in surface roughness RMS (μm), a judgment can be made as to whether a surface has a suitable fine concavo-convex structure as described above.

The value Δglanz / ΔRMS may be any value less than or equal to -800 as described above, but more preferably a value less than or equal to -1000, and more preferably a value that less than or equal to -1200.

The transparent substrate has at least one surface which satisfies the above-mentioned condition concerning ΔGlance / ΔRMS. In addition, the transparent substrate on both surfaces may have suitable fine concavo-convex structures as described above. That is, both surfaces of the transparent substrate can satisfy the above condition concerning ΔGlance / ΔRMS.

Further, by forming an appropriate fine concavo-convex structure on a surface of a transparent substrate as described above, light reflection can also be suppressed and the adhesion of fingerprints can be reduced. That is, regarding suppression of light reflection, it is considered that by arranging a fine concavo-convex structure on a surface of a transparent substrate, specular reflection at the substrate surface compared with a transparent substrate not having a surface having a fine concavo-convex structure has, can be suppressed in a suitable manner. Further, in terms of reducing the adhesion of fingerprints, it is considered that by forming a fine concavo-convex structure on a surface of a transparent substrate, finger marks, sweat and the like can be prevented from entering the recesses.

Further, the transparent substrate of the present embodiment is preferably formed to have a low reflectance, and therefore, the glossiness (%) of at least one surface of the transparent substrate is preferably less than or equal to 95%, and more preferably less than or equal to 90%. ,

The gloss (%) represents the suppression effect of the specular reflection of light as a result of the formation of a fine concavo-convex structure on the surface of the transparent substrate. If the gloss (%) is within the above range, mirror reflection of light on the surface of the transparent substrate can be suppressed, and in applications of various displays and touch screens, e.g. B. the visibility of the display can be improved. It should be noted that, in the case where fine concavo-convex structures are formed on both surfaces of a transparent substrate, at least one of the surfaces is preferably arranged to satisfy the aforementioned glossiness (%) condition. Further, both surfaces may be formed to satisfy the above condition.

For measuring the amount of change of gloss (%) with respect to the amount of change in surface roughness RMS (μm), etching is performed at least once on the surface of the transparent substrate subjected to the measurement and the surface roughness RMS (μm) and the gloss (%) is measured. In view of the improvement of the measurement accuracy, the etching is preferably performed at least twice under the same conditions as the first time, the gloss (%) and the surface roughness RMS (μm) are measured every time the etching is performed, a linear approximation of the plurality of measurement results is obtained and the value ΔGlanz / ΔRMS is calculated on the basis of its slope.

The method for producing the transparent substrate of the present embodiment is not particularly limited, and any method for forming a fine concavo-convex structure on at least one surface of a transparent substrate may be used, and thereby the transparent substrate of the present embodiment can be manufactured. For example, the surface of the transparent substrate using a suitable method, such as. As matting, sandblasting, lapping or the like, an abrasion to form a fine concavo-convex structure are subjected. Furthermore, z. For example, an etching method can be used in combination with these methods.

Of the above-mentioned methods, matting is preferably used to perform the surface treatment of the transparent substrate, so that a fine concavo-convex structure is formed on the surface of the transparent substrate. Matting can z. In terms of its ability to process a wide area in one operation, a short operation time and easy formation of fine bumps on a surface are preferably used. Further, in the case of forming fine unevenness on the surface of the transparent substrate by matting, the amount of processing, namely, the shape of the unevenness and the size of the unevenness, can be adjusted and a wider range of gloss (%) and haze (%) can be provided as compared to the case where other surface treatment methods are used. Thus, by selecting suitable matting conditions, a transparent substrate having the desired gloss (%) and haze (%) may be provided.

The material of the transparent substrate of the present embodiment is not particularly limited, and any transparent solid material may be used. For example, various types of materials including plastics and glass may be used as the material of the transparent substrate of the present embodiment. Of the aforementioned materials z. As glass is preferably used in view of its transparency and strength.

In this case, the type of glass is not particularly limited, and various types of glass, including alkali-free glass, soda-lime glass and aluminosilicate glass, can be used.

Further, the shape of the transparent substrate is not particularly limited. The transparent substrate need not be in the form of a flat plate, but it may, for. B. comprise a curved surface or have an atypical shape.

In the case where the transparent substrate of the present embodiment is made of soda-lime glass or aluminosilicate glass, the transparent substrate of the present embodiment may be further subjected to a known chemical process for increasing the strength.

The chemical strengthening method refers to a method in which alkali ions having a small ionic radius on the surface of a glass (eg, sodium ion) are replaced with alkali ion having a large ionic radius (eg, potassium ion) , For example, the process may be carried out by treating a glass containing sodium ions using a molten salt containing potassium ions. By carrying out such an ion exchange process, the composition of a deeper layer portion, which is suitably deeper from the glass substrate surface (in a broad sense a tensile stress layer), may be substantially identical to its composition prior to the ion exchange process, although the composition of a compressive stress layer is formed on the glass surface, according to the ion exchange method may be slightly different compared to their composition before the ion exchange process.

The process conditions for the chemical process for increasing the strength are not particularly limited and suitable conditions may be, for. For example, according to the type of the glass subjected to the chemical process for increasing the strength and the required degree of chemical increase of the strength.

The molten salt used in the chemical process for increasing the strength can be selected according to the glass substrate subjected to the chemical enhancement of the strength. For example, potassium nitrate, sodium sulfate, potassium sulfate, potassium carbonate, alkali metal sulfates and alkali chloride salts, such as. For example, sodium chloride and potassium chloride. These molten salts may be used alone or they may be used in combination.

The heating temperature of the molten salt is preferably greater than or equal to 350 ° C, and more preferably greater than or equal to 380 ° C. Further, the heating temperature is preferably less than or equal to 500 ° C, and more preferably less than or equal to 480 ° C.

By setting the heating temperature of the molten salt to be greater than or equal to 350 ° C, deterioration of the chemical strength increase due to a decrease in the ion exchange rate can be prevented. Further, by setting the heating temperature of the molten salt to less than or equal to 500 ° C, decomposition and deterioration of the molten salt can be prevented.

With regard to the time during which the glass comes into contact with the molten salt mixture, the process time is preferably greater than or equal to 1 hour, and more preferably greater than or equal to 2 hours, so that a sufficient compressive stress can be generated. Since the productivity tends to decrease and the compressive stress value due to relaxation can be reduced when a Ion exchange is carried out for a long period of time, the process time is preferably less than or equal to 24 hours, and more preferably less than or equal to 20 hours.

In the above, the transparent substrate according to the present embodiment has been described. As described above, according to the present embodiment, the transparent substrate has at least one area having a value ΔGlance / ΔRMS of less than or equal to -800, where ΔGlanz / ΔRMS is the amount of change of gloss (%) the amount of change in surface roughness RMS (μm) represents. When a fine concavo-convex structure formed on the surface of a transparent substrate satisfies the above-mentioned condition, it means that the fine concavo-convex structure has a suitable shape and size for suppressing light reflection, for reducing the adhesion of fingerprints and for suppressing unevenness of light scattering (glittering).

The transparent substrate according to the present embodiment can be used in various applications, for example, including displays such. A liquid crystal display or an organic EL, and touch screen applications. Of the various possible applications, the transparent substrate according to the present embodiment is particularly suitable for use in a display or a touch screen of a mobile device or device for a vehicle.

[APPLICATIONS]

Hereinafter, specific application examples of the present invention will be described. However, the present invention is not limited to these application examples. It should be noted that among the experiment examples described below, Experiment Examples 1 to 6 correspond to application examples of the present invention, and Experiment Examples 7 to 10 correspond to Comparative Examples.

(1) Evaluation procedure

Hereinafter, the characteristic evaluation methods used for the evaluation of transparent substrates obtained in the following experimental examples will be described.

<Gloss (%)>

The gloss was measured according to the method given in JIS Z 8741: 1997.

Specifically, a measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., product name: PG-IIM) for measuring the luminous flux of mirror reflection of light projected at a 60 ° angle (light source: tungsten lamp) onto a surface of a workpiece (sample a transparent substrate) which has been subjected to a surface treatment.

The amount of the reflected light measured in a corresponding manner with respect to a transparent substrate having no fine unevenness formed thereon (unprocessed transparent substrate) was set at 100% and the specular reflection luminous flux measured with respect to the specimen was indicated.

<RMS (μm)>

The RMS was measured according to the method given in JIS B 0601: 2001.

Specifically, an area of a measurement surface of a sample was defined as a measurement area P, and a measurement was made with respect to a field of view of 300 μm × 200 μm using a laser microscope (Keyence Corporation, product name: VK-9700). The upper limit was λc = 0.08 mm.

<ΔGloss (%) / ΔRMS (μm)>

The gloss (%) and RMS (μm) of a sample of a transparent substrate that has been obtained were measured in advance using the methods described above.

Then, the sample was immersed in hydrofluoric acid at a concentration of 5% by weight based on the total amount for 3 minutes, after which the sample was taken out and washed with distilled water, and the gloss (%) and RMS (μm) were again lowered Use of the measuring methods described above. The procedure of immersing the sample in hydrofluoric acid for 3 minutes, washing the sample, and measuring the gloss (%) and RMS (μm) was repeated twice more in a similar manner. It should be noted that in the measurement of the RMS, the measurement was made every time in the same measurement range P.

Regarding the four measurement results of the sample, the least squares method was used to obtain regression lines for the gloss (%) and the surface roughness RMS (μm), and the value Δglass / ΔRMS was calculated based on their slopes.

It should be noted that the following evaluations of haze, diameter of fine bumps and sparkle have been made before performing the above measurements (before re-etching with hydrofluoric acid).

<Haze>

Haze was measured according to the method given in JIS K 7136.

In particular, a turbidimeter (manufactured by Suga Test Instruments Co., Ltd., product name: HZ-2) was used to perform the measurement.

<Diameter of fine bumps>

With respect to a field of view P of 300 μm × 200 μm of the measurement surface of the sample, the height distribution of the measurement surface was measured by means of a laser microscope. Then, to eliminate noise due to shape variations, binarization was performed by using a value obtained by subtracting 1 μm from the highest point of the measured surface as a threshold. Then, a circle approximation was made on the unevenness in the image obtained by the binarization, and the diameters of the circles were calculated. Then, the median diameter of the calculated diameter was set as the diameter of fine unevenness.

<Rating of Glittering>

The transparent substrate obtained was coated on a liquid crystal display of an iPhone4S (manufactured by Apple), and a measuring range of 50 mm × 50 mm square was set. Then, the unevenness of the light scattering was evaluated by (A) performing a visual inspection of the substrate fixed to the liquid crystal display, and (B) performing a visual inspection of the substrate while moving the substrate at 1 mm / second with respect to the liquid crystal display. Because of the characteristics of the human eye, more precise measurements can be made by performing a visual inspection while the substrate is being moved. The evaluation was carried out by counting the obtained number of glittering dots in the following manner.

• 1: Kein Glitzern wahrgenommen, selbst wenn das Substrat bewegt wird
• 2: Nicht mehr als 3 Punkte eines geringfügigen Glitzerns wahrgenommen, wenn das Substrat bewegt wird
• 3: Nicht mehr als 2 Punkte eines Glitzerns wahrgenommen, wenn das Substrat fixiert ist, jedoch 4 oder mehr Punkte eines geringfügigen Glitzerns wahrgenommen, wenn das Substrat bewegt wird
• 4: 3 oder mehr Punkte eines Glitzerns wahrgenommen, selbst wenn das Substrat fixiert ist
• 5: Ein Glitzern wird von der gesamten Oberfläche wahrgenommen, selbst wenn das Substrat fixiert ist

The evaluation was made on the basis of the following criteria and a rating on a scale of 1 to 5 points was assigned. A lower rating means that unevenness of light scattering (glittering) is suppressed, and a score of 3 points or lower is considered a passed score.

• 1: No glint perceived even when the substrate is moved
• 2: Not more than 3 points of a slight sparkle perceived when the substrate is moved
• 3: Not more than 2 points of sparkling are perceived when the substrate is fixed, but 4 or more points of a slight sparkle are perceived when the substrate is moved
• 4: 3 or more points of glitter are perceived even when the substrate is fixed
• 5: A glint is perceived by the entire surface even when the substrate is fixed

(2) Experimental procedure

Experiment Example 1

• (1) Ein 1,3 mm dickes Aluminosilikat-Glassubstrat mit 5 cm im Quadrat wurde durch Eintauchen des Glassubstrats in eine 2,5 Gew.-%ige Fluorwasserstoffsäure für 30 Sekunden vorgewaschen.
• (2) Eine Mattierungsbehandlungslösung wurde durch Lösen von 150 g Kaliumfluorid und 300 ml einer 50 Gew.-%igen wässrigen Fluorwasserstofflösung in einem Gemisch aus 350 ml reinem Wasser und 350 ml Eisessig hergestellt.
• (3) Das Glassubstrat wurde in die vorstehend beschriebene Mattierungsbehandlungslösung für 30 Sekunden eingetaucht, um einen Vorätzvorgang durchzuführen.
• (4) Das Aluminosilikat-Glassubstrat wurde aus der Mattierungsbehandlungslösung entnommen, 10 Minuten mit fließendem Wasser gewaschen und danach einem Ätzvorgang durch Eintauchen in eine 5 Gew.-%ige wässrige Fluorwasserstofflösung für 6 Minuten unterzogen. Auf diese Weise wurde eine feine konkav-konvexe Form auf der Oberfläche des Aluminosilikat-Glassubstrats gebildet, das dem transparenten Substrat entspricht.

A fine concavo-convex shape was formed on a surface of a glass substrate corresponding to a transparent substrate according to the following operations.

• (1) A 1.3 mm thick 5 cm square aluminosilicate glass substrate was prewashed by immersing the glass substrate in a 2.5 wt% hydrofluoric acid for 30 seconds.
• (2) A matting treatment solution was prepared by dissolving 150 g of potassium fluoride and 300 ml of a 50 wt% aqueous hydrogen fluoride solution in a mixture of 350 ml of pure water and 350 ml of glacial acetic acid.
• (3) The glass substrate was dipped in the above-described dulling treatment solution for 30 seconds to perform a pre-etching process.
• (4) The aluminosilicate glass substrate was taken out of the matting treatment solution, washed with running water for 10 minutes, and then subjected to etching by immersion in a 5 wt% aqueous hydrogen fluoride solution for 6 minutes. In this way, a fine concavo-convex shape was formed on the surface of the aluminosilicate glass substrate corresponding to the transparent substrate.

The obtained sample was subjected to the above-mentioned evaluation method to obtain evaluations of gloss, surface roughness RMS, Δ gloss / ΔRMS, haze, fine unevenness diameter and evaluation of glitter.

Experiment Example 2

Other than the change of the matting treatment solution to a solution prepared by dissolving 150 g of potassium fluoride and 300 ml of a 50 wt.% Aqueous solution of hydrogen fluoride in 700 ml of pure water, operations similar to those of Experiment Example 1 were carried out. so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 1.

In the present experiment example, a surface examination of an area of the transparent substrate was carried out by using a laser microscope (manufactured by Keyence Corporation, product name: VK-9700). The 2 is a laser microscope image of the surface being examined.

Further, line (a) in FIG 4 a regression line obtained by calculating the value ΔGlance / ΔRMS in the present experiment example.

Experiment Example 3

Except for the change of the matting treatment solution to a solution prepared by dissolving 100 g of potassium fluoride and 200 ml of a 50% by weight aqueous solution of hydrogen fluoride in a mixture of 400 ml of pure water and 400 ml of glacial acetic acid, operations became the same of Experiment Example 1, so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 1.

Experiment Example 4

Except for changing the matting treatment solution to a solution prepared by dissolving 100 g of potassium fluoride and 200 ml of a 50 wt% aqueous solution of hydrogen fluoride in 800 ml of pure water, operations similar to those of Experiment Example 1 were carried out. so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 1.

Experiment Example 5

Apart from the change of the matting treatment solution to a solution prepared by dissolving 30 g of potassium fluoride and 60 ml of a 50% by weight aqueous solution of hydrogen fluoride in a mixture of 470 ml of pure water and 470 ml of glacial acetic acid, operations became the same of Experiment Example 1, so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 1.

Experiment Example 6

Except for changing the matting treatment solution to a solution prepared by dissolving 30 g of potassium fluoride and 60 ml of a 50 wt% aqueous solution of hydrogen fluoride in 940 ml of pure water, operations similar to those in Experiment Example 1 were carried out. so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 1.

[Experiment Example 7]

• (1) Eine Mattierungsbehandlungslösung wurde durch Zusetzen von 1500 g Ammoniumfluorid und 1200 g Glasperlen mit einem durchschnittlichen Teilchendurchmesser von 4 μm zu 1000 ml einer 50 Gew.-%igen wässrigen Fluorwasserstofflösung und Rühren hergestellt.
• (2) Ein 1,3 mm dickes Aluminosilikat-Glassubstrat mit 5 cm im Quadrat wurde in die vorstehend beschriebene Mattierungsbehandlungslösung für 8 Minuten eingetaucht, um einen Vorätzvorgang durchzuführen.
• (3) Das Aluminosilikat-Glassubstrat wurde aus der Mattierungsbehandlungslösung entnommen, 10 Minuten mit fließendem Wasser gewaschen und danach einem Ätzvorgang durch Eintauchen in eine 20 Gew.-%ige wässrige Fluorwasserstofflösung für 16 Minuten unterzogen. Auf diese Weise wurde eine feine konkav-konvexe Form auf einer Oberfläche des Aluminosilikat-Glassubstrats gebildet, das einem transparenten Substrat entspricht.

A fine concavo-convex shape was formed on a surface of a glass substrate corresponding to a transparent substrate according to the following operations.

• (1) A matting treatment solution was prepared by adding 1500 g of ammonium fluoride and 1200 g of glass beads having an average particle diameter of 4 μm to 1000 ml of a 50 wt% aqueous hydrogen fluoride solution and stirring.
• (2) A 1.3 mm thick 5 cm square aluminosilicate glass substrate was immersed in the above-described matting treatment solution for 8 minutes to carry out a pre-etching process.
• (3) The aluminosilicate glass substrate was taken out of the matting treatment solution, washed with running water for 10 minutes, and then subjected to etching by immersion in a 20 wt% aqueous hydrogen fluoride solution for 16 minutes. In this way, a fine concavo-convex shape was formed on a surface of the aluminosilicate glass substrate corresponding to a transparent substrate.

The obtained sample was subjected to the above-mentioned evaluation method to obtain evaluations of gloss, surface roughness RMS, Δ gloss / ΔRMS, haze, fine unevenness diameter and evaluation of glitter.

Experiment Example 8

Other than the change of the matting treatment solution to a solution prepared by adding 500 g of ammonium fluoride and 120 g of glass beads having an average particle diameter of 4 μm to 1000 ml of a 50 wt% aqueous solution of hydrogen fluoride, operations similar to those of Experiment Example 7 was performed, so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 7.

As in the experiment example 2, a surface examination of an area of the obtained transparent substrate was performed. The 3 is a laser microscope image of the surface being examined.

Further, the line (b) in the 4 a regression line obtained by calculating the value ΔGlance / ΔRMS in the present experiment example.

Experiment Example 9

Except for changing the matting treatment solution to a solution prepared by adding 500 g of ammonium fluoride to 1000 ml of a 50 wt% aqueous solution of hydrogen fluoride Operations similar to those of Experiment Example 7 were carried out so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 7.

Experiment Example 10

Except for changing the matting treatment solution to a solution prepared by adding 1500 g of ammonium fluoride and 120 g of glass beads having an average particle diameter of 4 μm to a mixture of 770 ml of a 65 wt% aqueous solution of hydrogen fluoride and 230 ml of glacial acetic acid , operations similar to those of Experiment Example 7 were performed so that a fine concavo-convex shape was formed on a surface of a transparent substrate.

The obtained sample was evaluated in a manner similar to that of Experiment Example 7.

The results of Experiment Examples 1 to 10 are shown in Table 1 below.

As is apparent from these results, with respect to Experiment Examples 1 to 6 in which the values ΔGlance / ΔRMS satisfy the condition of the present invention, the glitter ratings are less than or equal to 3 points, indicating that transparent substrates have been obtained where a glint can be suppressed.

Further, since suitable fine concavo-convex structures are formed on the transparent substrates obtained in Experiment Examples 1 to 6, light reflection can be suppressed and the light reflectance can be suppressed as compared with a transparent substrate having no fine concavo-convex structure formed thereon Liability of fingerprints can be reduced.

Furthermore, in a comparison of 2 and 3 5, which illustrate investigations of the concavo-convex shapes of Experiment Example 2 and Experiment Example 8, it can be seen that in the transparent substrate of Experiment Example 2, as compared with the transparent substrate of Experiment Example 8, very fine pits are formed. It can be seen that by the presence of such a structure, glitter can be suppressed. Such an effect can also be seen in the values of ΔGlanz / ΔRMS in Experiment Example 2 and Experiment Example 8.

Although the above illustrative embodiments and application examples of a transparent substrate according to the present invention have been described, the present invention is not limited to the embodiments and application examples described above, and various variations and modifications can be made without departing from the scope of the deviate from the present invention.

The present application is based on and claims the priority of Japanese Patent Application No. 2013-008275 , filed January 21, 2013, the entire contents of which are incorporated herein by reference.

Claims (4)

A transparent substrate having at least one area with a Δglass / ΔRMS value of less than or equal to -800, wherein the Δblance / ΔRMS value represents the amount of gloss change (%) based on the amount of surface roughness change RMS (μm) , A transparent substrate according to claim 1, wherein the transparent substrate is made of glass. A transparent substrate according to claim 1 or 2, wherein the gloss (%) of at least one surface of the transparent substrate is less than or equal to 95%. A transparent substrate according to any one of claims 1 to 3, wherein a surface treatment of the transparent substrate has been performed by matting.

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