JP7124299B2 - transparent goods - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent article having a rough uneven surface such as an anti-glare surface.

From the viewpoint of improving the visibility of a display device, it has been proposed to make the surface of a transparent article arranged on the display surface of the display device a rough anti-glare surface. Patent Document 1 discloses that sparkle (glare due to sparkle phenomenon) is suppressed by setting the surface roughness Sq (RMS surface roughness) of an anti-glare surface provided on the surface of a transparent glass plate to a specific range. is disclosed. Specifically, a first surface roughness Sq(S1) up to 300 nm measured over a lateral spatial period range of 40 μm to 640 μm and a first surface roughness Sq(S1) measured over a lateral spatial period range of less than 20 μm It is disclosed that sparkle is suppressed by setting the ratio (S1/S2) to the surface roughness Sq (S2) of No. 2 to less than 3.9.

Japanese Patent No. 6013378

By the way, the higher the definition of the display device, the more conspicuous the sparkle of the transparent article arranged on the display surface of the display device. Therefore, as display devices become higher in definition, transparent articles are also required to have a higher effect of suppressing sparkle.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a transparent article that suppresses sparkle on a rough uneven surface such as an anti-glare surface.

The present inventors have found that when the surface roughness Sq measured at a spatial period of 20 μm or more on a rough uneven surface such as an anti-glare surface is 50 nm or less, sparkle in a transparent article is significantly suppressed. rice field.

That is, a transparent article that solves the above problems is a transparent article that includes a transparent substrate and a rough uneven surface provided on at least one surface of the transparent substrate, wherein the uneven surface has a thickness of 20 μm. The surface roughness Sq measured with the lateral spatial period is 50 nm or less.

In the above transparent article, the uneven surface preferably has a surface roughness Sq of 5 nm or more measured at a lateral spatial period of 20 μm or more.
In the above transparent article, the uneven surface preferably has a surface roughness Sq of 26 nm or more measured without filtering. Measurement without filtering means measurement without using a filter such as a low-pass filter or a high-pass filter.

In the above transparent article, the uneven surface preferably has a surface roughness Sq of 50 nm or more measured without filtering.
In the above transparent article, the uneven surface preferably has a surface roughness Sq of 26 nm or less measured at a lateral spatial period of 20 μm or more, and a surface roughness Sq of less than 50 nm measured without filtering. .

In the above transparent article, it is preferable that the uneven surface is composed of an uneven layer containing at least one selected from SiO ₂ , Al ₂ O ₃ , ZrO ₂ and TiO ₂ .

According to the transparent article of the present invention, it is possible to suppress sparkle on a rough uneven surface such as an anti-glare surface.

Explanatory drawing of a transparent article. Explanatory drawing of the measuring method of a sparkle value. Explanatory drawing of a pattern mask. The graph which shows the relationship between Sq [≧20 μm] and the sparkle value. 5 is a graph showing the relationship between the surface roughness Sq ratio and the sparkle value;

An embodiment of the present invention will be described below.
As shown in FIG. 1, the transparent article 10 includes a translucent transparent substrate 11 having a plate shape. The thickness of the transparent base material 11 is, for example, 0.1 to 5 mm. Examples of the material of the transparent substrate 11 include glass and resin. The material of the transparent substrate 11 is preferably glass, and known glass such as non-alkali glass, aluminosilicate glass, and soda lime can be used as the glass. Further, tempered glass such as chemically tempered glass or crystallized glass such as LAS crystallized glass can be used. Among these, it is preferable to use an aluminosilicate glass, in particular, SiO ₂ : 50 to 80%, Al ₂ O ₃ : 5 to 25%, B ₂ O ₃ : 0 to 15%, Na ₂ O: Chemically strengthened glass containing 1 to 20% K ₂ O and 0 to 10% K 2 O is preferably used. Examples of resins include polymethyl methacrylate, polycarbonate, and epoxy resins.

On one main surface of the transparent substrate 11, an uneven layer 12 having an uneven surface 12a, which is a rough surface having an uneven structure, is provided. The concave-convex surface 12a is, for example, an anti-glare surface that scatters light and suppresses glare due to the concave-convex structure. be provided. The uneven layer 12 and its uneven structure are composed of a matrix made of inorganic oxides such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ and TiO ₂ . An example of the concave-convex structure of the concave-convex surface 12a is an island-shaped concave-convex structure having flat portions between a plurality of island-shaped convex portions. It is preferable that the uneven layer 12 is composed only of inorganic oxides or does not contain organic compounds.

The uneven layer 12 can be formed, for example, by applying a coating agent containing a matrix precursor and a liquid medium that dissolves the matrix precursor to the surface of the transparent substrate 11 and heating the coating. Examples of matrix precursors contained in the coating agent include inorganic precursors such as silica precursors, alumina precursors, zirconia precursors, and titania precursors. A silica precursor is preferable because it lowers the refractive index of the uneven layer 12 and facilitates control of reactivity.

Silica precursors include silane compounds having a hydrocarbon group and a hydrolyzable group bonded to a silicon atom, hydrolytic condensates of silane compounds, silazane compounds, and the like. It is preferable that at least one or both of a silane compound and a hydrolytic condensate thereof is contained in order to sufficiently suppress cracks in the uneven layer 12 even when the uneven layer 12 is formed thick.

The silane compound has a hydrocarbon group bonded to the silicon atom and a hydrolyzable group. The hydrocarbon group is one or two selected from -O-, -S-, -CO-, and -NR'- (R' is a hydrogen atom or a monovalent hydrocarbon group) between carbon atoms. You may have groups in which two or more are combined.

The hydrocarbon group may be a monovalent hydrocarbon group bonded to one silicon atom or a divalent hydrocarbon group bonded to two silicon atoms. Examples of monovalent hydrocarbon groups include alkyl groups, alkenyl groups, and aryl groups. Examples of divalent hydrocarbon groups include alkylene groups, alkenylene groups, and arylene groups.

Examples of hydrolyzable groups include alkoxy groups, acyloxy groups, ketoxime groups, alkenyloxy groups, amino groups, aminoxy groups, amide groups, isocyanate groups, halogen atoms and the like. An alkoxy group, an isocyanate group, and a halogen atom (especially a chlorine atom) are preferable from the point of balance with. As the alkoxy group, an alkoxy group having 1 to 3 carbon atoms is preferable, and a methoxy group or an ethoxy group is more preferable.

Silane compounds include alkoxysilanes (tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, etc.), alkoxysilanes having an alkyl group (methyltrimethoxysilane, ethyltriethoxysilane, etc.), and alkoxysilanes having a vinyl group (vinyl trimethoxysilane, vinyltriethoxysilane, etc.), alkoxysilanes having an epoxy group (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.), alkoxysilanes having an acryloyloxy group (3-acryloyloxypropyltrimethoxysilane, etc.), and the like. Among these silane compounds, it is preferable to use one or both of the alkoxysilane and the hydrolytic condensate of alkoxysilane, and it is more preferable to use the hydrolytic condensate of alkoxysilane.

A silazane compound is a compound having a silicon-nitrogen bond (--SiN--) in its structure. The silazane compound may be a low-molecular-weight compound or a high-molecular-weight compound (a polymer having a predetermined repeating unit). Examples of low-molecular-weight silazane compounds include hexamethyldisilazane, hexaphenyldisilazane, dimethylaminotrimethylsilane, trisilazane, cyclotrisilazane, and 1,1,3,3,5,5-hexamethylcyclotrisilazane. be done.

Examples of alumina precursors include aluminum alkoxides, hydrolytic condensates of aluminum alkoxides, water-soluble aluminum salts, and aluminum chelates. Zirconia precursors include zirconium alkoxides, hydrolytic condensates of zirconium alkoxides, and the like. Examples of titania precursors include titanium alkoxides and hydrolytic condensates of titanium alkoxides.

The liquid medium contained in the coating agent is a solvent that dissolves the matrix precursor, and is appropriately selected according to the type of matrix precursor. Examples of liquid media include water, alcohols, ketones, ethers, cellosolves, esters, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds.

Alcohols include methanol, ethanol, isopropanol, butanol, diacetone alcohol and the like. Ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone and the like. Ethers include tetrahydrofuran, 1,4-dioxane and the like. Cellosolves include methyl cellosolve, ethyl cellosolve, and the like. Examples of esters include methyl acetate and ethyl acetate. Glycol ethers include ethylene glycol monoalkyl ether and the like. Nitrogen-containing compounds include N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone and the like. Dimethyl sulfoxide etc. are mentioned as a sulfur-containing compound. The liquid medium may be used alone or in combination of two or more.

The liquid medium is preferably a liquid medium containing water, that is, water or a mixture of water and another liquid medium. Alcohols are preferred as other liquid media, and methanol, ethanol, isopropyl alcohol and butanol are particularly preferred.

The coating agent may also contain an acid catalyst that promotes hydrolysis and condensation of the matrix precursor. The acid catalyst is a component that promotes hydrolysis and condensation of the matrix precursor and forms the uneven layer 12 in a short time. The acid catalyst may be added for hydrolysis and condensation of raw materials (alkoxysilane, etc.) during the preparation of the matrix precursor solution prior to preparation of the coating agent. It may be added after preparation. Acid catalysts include inorganic acids (nitric acid, sulfuric acid, hydrochloric acid, etc.) and organic acids (formic acid, oxalic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, etc.).

As a method for applying the coating agent, known wet coating methods (spray coating method, spin coating method, dip coating method, die coating method, curtain coating method, screen coating method, inkjet method, flow coating method, gravure coating method, bar coating method, method, flexo coating method, slit coating method, roll coating method, etc.). As the coating method, the spray coating method is preferable because it facilitates the formation of irregularities.

The nozzle used in the spray coating method includes a two-fluid nozzle, a one-fluid nozzle, and the like. The particle diameter of droplets of the coating agent discharged from the nozzle is usually 0.1 to 100 μm, preferably 1 to 50 μm. If the particle size of the droplet is 0.1 μm or more, it is possible to form in a short period of time unevenness that sufficiently exhibits the antiglare effect. When the droplet diameter is 100 μm or less, it is easy to form moderate irregularities that sufficiently exhibit the antiglare effect. The particle size of the droplets of the coating agent can be appropriately adjusted by the type of nozzle, spray pressure, liquid volume, and the like. For example, in a two-fluid nozzle, the higher the spray pressure, the smaller the droplets, and the larger the liquid volume, the larger the droplets. In addition, the particle size of the droplet is the Sauter mean particle size measured by a laser measuring device.

The surface temperature of the coating object (for example, the transparent substrate 11) when the coating agent is applied is, for example, 20 to 75°C, preferably 35°C or higher, and more preferably 60°C or higher. As a method for heating the object to be coated, it is preferable to use, for example, a hot water circulation type heating device. Also, the humidity when applying the coating agent is, for example, 20 to 80%, preferably 50% or more.

In the transparent article 10, the surface roughness Sq of the uneven surface 12a, which is the surface of the uneven layer 12, is set within a specific range. In addition, the surface roughness Sq is the surface roughness Sq measured based on ISO25178.

More specifically, the uneven surface 12a has a surface roughness Sq (Sq [≧20 μm]) of 50 nm or less measured at a lateral spatial period of 20 μm or more. Also, Sq [≧20 μm] is preferably 40 nm or less, more preferably 26 nm or less, and even more preferably 20 nm or less. By setting Sq [≧20 μm] to 50 nm or less, sparkle on the uneven surface 12a of the transparent article 10 is significantly suppressed, and by setting it to 26 nm or less, sparkle is further significantly suppressed. Note that the lower limit of Sq [≧20 μm] is, for example, 5 nm.

The surface roughness Sq (Sq[All]) of the uneven surface 12a measured without filtering is preferably 26 nm or more, more preferably 50 nm or more, and even more preferably 60 nm or more. In this case, since reflection on the uneven surface 12a can be effectively suppressed, it is effective when the uneven surface 12a is applied as an anti-glare surface. The upper limit of the surface roughness Sq (Sq[All]) measured without filtering is, for example, 300 nm.

In addition, the uneven surface 12a has a surface roughness Sq (Sq [≧20 μm]) of 26 nm or less measured at a lateral spatial period of 20 μm or more, and a surface roughness Sq (Sq [All] ) is preferably less than 50 nm. Furthermore, the surface roughness Sq (Sq [≧20 μm]) measured at a lateral spatial period of 20 μm or more is 20 nm or less, and the surface roughness Sq (Sq [All]) measured without filtering is 40 nm or less. Preferably. In this case, since the uneven surface 12a has a glossy texture, it is effective when the uneven surface 12a is applied as a surface for improving writing comfort. Note that the lower limit of Sq[All] is, for example, 26 nm.

The uneven surface 12a has a surface roughness Sq (Sq [≧40 μm]) measured at a horizontal spatial period of 40 μm or more and a surface roughness Sq (Sq [≦20 μm]) (Sq[≧40 μm]/Sq[≦20 μm]) is preferably 0.70 or less, more preferably 0.40 or less.

In addition, the uneven surface 12a has a surface roughness Sq (Sq [≧20 μm]) of 5 nm or more measured at a lateral spatial period of 20 μm or more, and a surface roughness Sq (Sq [All]) is preferably 26 nm or more. The uneven surface 12a having a surface roughness Sq of 5 nm or more measured at a lateral spatial period of 20 μm or more is suitable as an anti-glare surface. Further, the uneven surface 12a having a surface roughness Sq (Sq[All]) of 26 nm or more measured without filtering is suitable as a surface for improving writing comfort.

Various surface roughnesses Sq of the uneven surface 12a can be controlled by changing the conditions for forming the uneven layer 12. FIG. For example, when forming the concavo-convex layer 12 by a spray coating method, Sq[≧20 μm] and Sq[All] increase when the coating amount of the coating agent is increased. Also, when the particle size of the droplet of the coating agent is reduced, Sq [≧20 μm] is reduced.

The transparent article 10 configured as described above is used, for example, placed on the display surface of a display device (for example, a display with a pixel density of 200 ppi to 800 ppi). In this case, the transparent article 10 may be a member attached on the display surface of the display device. That is, the transparent article 10 may be a member that is attached to the display device afterward.

Next, the operation and effects of this embodiment will be described.
(1) The transparent article 10 includes a transparent substrate 11 and a rough uneven surface 12 a provided on one surface of the transparent substrate 11 . The uneven surface 12a has a surface roughness Sq (Sq[≧20 μm]) of 50 nm or less measured at a lateral spatial period of 20 μm or more.

The uneven surface 12a with Sq[≧20 μm] of 50 nm or less significantly suppresses sparkle compared to the uneven surface 12a with Sq[≧20 μm] exceeding 50 nm. Therefore, a transparent article in which sparkle on the uneven surface 12a is suppressed is obtained.

(2) The uneven surface 12a has an Sq [≧20 μm] of 26 nm or less.
Among the uneven surfaces 12a having Sq[≧20 μm] of 50 nm or less, the uneven surfaces 12a having Sq[≧20 μm] of 26 nm or less have more sparkle than the uneven surfaces 12a having Sq[≧20 μm] exceeding 26 nm. markedly suppressed. Therefore, a transparent article is obtained in which sparkle on the uneven surface 12a is further suppressed.

(3) The uneven surface 12a has a surface roughness Sq of 5 nm or more measured at a lateral spatial period of 20 μm or more. According to the above configuration, the uneven surface 12a can be suitably applied as an anti-glare surface.

(4) The uneven surface 12a has a surface roughness Sq of 26 nm or more measured without filtering. According to the above configuration, the uneven surface 12a can be suitably applied as a surface for improving writing comfort.

(5) The uneven surface 12a has a surface roughness Sq of 50 nm or more measured without filtering. According to the above configuration, reflection on the uneven surface 12a can be effectively suppressed, so the uneven surface 12a can be suitably applied as an anti-glare surface.

(6) The uneven surface 12a preferably has a surface roughness Sq of 26 nm or less measured at a lateral spatial period of 20 μm or more, and a surface roughness Sq of less than 50 nm measured without filtering. According to the above configuration, the uneven surface 12a has a glossy texture while giving the tactile sensation of a rough surface. Therefore, the uneven surface 12a can be suitably applied as a surface for improving writing comfort.

(7) The uneven surface 12a is composed of the uneven layer 12 containing at least one selected from SiO ₂ , Al ₂ O ₃ , ZrO ₂ and TiO ₂ . In this case, the above effects (1) to (6) can be obtained more reliably.

It should be noted that this embodiment can also be embodied by changing as follows.
- The transparent article 10 may have other layers such as an antireflection layer and an antifouling layer in addition to the transparent substrate 11 and the uneven layer 12 .

- The uneven surface 12 a is not limited to the surface of the uneven layer 12 provided on one main surface of the transparent substrate 11 . For example, the surface of the transparent substrate 11 may be an uneven surface having an uneven structure formed by other methods such as blasting and etching.

- The uneven surface 12a may be provided on two or more surfaces of the transparent substrate 11 .
Next, technical ideas that can be grasped from the above embodiment and modifications will be described.
(a) The transparent article, wherein the uneven surface has a surface roughness Sq of 26 nm or less measured at a lateral spatial period of 20 μm or more.

(b) The uneven surface has a surface roughness Sq (Sq [≧40 μm]) measured at a lateral spatial period of 40 μm or more and a surface roughness Sq measured at a lateral spatial period of 20 μm or less ( Sq [≦20 μm]) ratio (Sq [≧40 μm]/Sq [≦20 μm]) is 0.70 or less.

(c) A transparent article comprising a transparent substrate and an anti-glare surface provided on at least one surface of the transparent substrate, wherein the anti-glare surface is a surface measured with a lateral spatial period of 20 μm or more. A transparent article having a roughness Sq of 50 nm or less.

(d) A transparent article comprising a transparent substrate and a tactile sensation-imparting surface provided on at least one surface of the transparent substrate, wherein the tactile sensation-imparting surface is measured at a lateral spatial period of 20 μm or more. A transparent article having a surface roughness Sq of 50 nm or less.

(e) A transparent article comprising a transparent substrate and a rough uneven surface provided on at least one surface of the transparent substrate, wherein the uneven surface has a horizontal spatial period of 20 μm or more. A transparent article having a measured surface roughness Sq of 50 nm or less and used in a display with a pixel density of 200 ppi to 800 ppi.

Test examples are given below to describe the above embodiments more specifically. In addition, this invention is not limited to these.
(Test Examples 1 to 16)
Transparent articles of Test Examples 1 to 16 having uneven surfaces with different surface roughness Sq were produced.

By applying a coating agent to the surface of one side of a transparent base material (manufactured by Nippon Electric Glass Co., Ltd.: T2X-1) made of plate-shaped chemically strengthened glass with a thickness of 1.3 mm using a spray coating device. An uneven layer having a rough uneven surface was formed. The nozzle of the spray coating device is a two-fluid nozzle, and the coating agent is a solution prepared by dissolving the precursor of the uneven layer (tetraethyl orthosilicate) in a liquid medium containing water. It was applied to the transparent substrate at 0.3 kg/hr. As shown in Tables 1 and 2, the transparent articles of Test Examples 1 to 16 had a coating amount per unit area of the coating agent when forming the uneven layer, a spray air flow rate jetted together with the coating agent, and a transparent substrate. The surface roughness Sq of the concave-convex surface was changed by changing the surface temperature and the atmospheric humidity.

(Measurement of surface roughness Sq)
The surface roughness Sq of the uneven surface of the transparent article of each test example was measured in accordance with ISO25178. Three-dimensional data of the uneven surface of the transparent article was measured using a scanning white light interference microscope (VertScan, manufactured by Ryoka System Co., Ltd.). The measurement conditions are as follows.

Measurement mode: WAVE mode Filter: 530 white filter Objective lens: 20x objective lens Measurement area: 316.77 µm x 237.72 µm
Resolution: 640 pixels×480 pixels Next, the measured three-dimensional data was subjected to primary surface correction using analysis software VS-Viewer to obtain roughness data, from which the surface roughness Sq was calculated. The results are shown in Tables 3 and 4. The surface roughness Sq shown in the "All" column of Tables 3 and 4 is the surface roughness Sq calculated without filtering from the obtained roughness data. The surface roughness Sq shown in the "≧20 μm" column is the surface roughness Sq calculated with a horizontal spatial period of 20 μm or more using a low-pass filter of FFT2 function of VS-Viewer. The surface roughness Sq shown in the column "≧40 μm" is the surface roughness Sq calculated with a horizontal spatial period of 40 μm or more using a low-pass filter with FFT2 function. The surface roughness Sq shown in the "≦20 μm" column is the surface roughness Sq calculated with a horizontal spatial period of 20 μm or less using a high-pass filter of FFT2 function of VS-Viewer.

In addition, for the transparent article of each test example, the surface roughness Sq (Sq [≧40 μm]) measured at a lateral spatial period of 40 μm or more and the surface roughness measured at a lateral spatial period of 20 μm or less A ratio (Sq[≧40 μm]/Sq[≦20 μm]) to Sq (Sq[≦20 μm]) was obtained. The results are shown in the "Sq [≧40 μm]/Sq [≦20 μm]" columns of Tables 3 and 4.

(Measurement of sparkle value)
The sparkle value of the uneven surface of the transparent article of each test example was measured. The results are shown in the "sparkle value" column of Tables 3 and 4.

The sparkle value was obtained by arranging a surface light source on the opposite side of the uneven surface of the transparent article with the pattern mask interposed therebetween, and measuring the uneven surface of the transparent article and the pattern mask within the front depth of field at a permissible circle of confusion diameter of 53 μm. The transparent article is imaged from the uneven surface side so that the top surface is included, and the standard deviation of the pixel brightness of the pattern mask obtained by analyzing the image data obtained by analyzing the image data. It is a value divided by the average pixel brightness of the pattern mask obtained by The sparkle value is a value indicating the degree of sparkle on the uneven surface, and the more the sparkle on the uneven surface is suppressed, the lower the sparkle value. By using the sparkle value, it is possible to perform a quantitative evaluation of sparkle that is similar to image recognition based on human vision.

A specific method for measuring the sparkle value will be described below.
As shown in FIG. 2, a pattern mask 21 is placed on a surface light source 20, and a transparent mask is placed on the pattern mask 21 so that the surface opposite to the uneven surface 12a faces the pattern mask 21 side. An article 10 is placed. Further, a photodetector 22 having a permissible circle of confusion diameter of 53 μm was arranged on the uneven surface 12 a side of the transparent article 10 .

As the pattern mask 21, as shown in FIG. 3, a 500 ppi pattern mask with a pixel pitch of 50 μm and a pixel size of 10 μm×40 μm was used. As the photodetector 22, SMS-1000 (manufactured by Display-Messtechnik & Systeme) was used. The photodetector 22 has a sensor size of 1/3 type and a pixel size of 3.75 μm×3.75 μm. The focal length of the lens of the photodetector 22 is 100 mm, and the lens aperture diameter is 4.5 mm. The pattern mask 21 is arranged so that its top surface 21a is positioned at the focal position of the photodetector 22, and the transparent article is positioned so that the distance from the top surface 21a of the pattern mask 21 to the uneven surface 12a is 1.8 mm. placed in

Next, the uneven surface 12 a of the transparent article 10 is irradiated with light from the surface light source 20 through the pattern mask 21 , and the image of the transparent article 10 is captured by the photodetector 22 to detect the uneven surface 12 a of the transparent article 10 . Image data of the surface 12a was acquired. The obtained image data is analyzed by the sparkle measurement mode of SMS-1000 (software Sparkle measurement system), and the pixel brightness of each pixel of the pattern mask 21, the pixel brightness standard deviation between pixels, and the pixel brightness average value asked for A sparkle value was calculated by the following formula (1) based on the obtained standard deviation of pixel brightness between pixels and the average value of pixel brightness.

Sparkle value=[standard deviation of pixel brightness of pattern mask]/[average value of pixel brightness of pattern mask] (1)
(Sensory evaluation of sparkle)
The transparent article of each test example was placed on the display surface of a display device (Huawei smartphone: H1512) with a resolution of 518 ppi, with the uneven surface facing upward. Ten panelists were asked to observe images on the display device through the transparent article of each test example and evaluate whether or not they felt glare. The results are shown in the "sensory evaluation" column of Tables 3 and 4. In the "sensory evaluation" column, the number of people who evaluated that they felt glare was "◎", the number of people who evaluated that they felt the glare was "◎", the number of 2 to 3 people was "○", and the number of 4 to 8 people was evaluated. are indicated by "△", and those with 9 or more persons are indicated by "×".

(Measurement of gross value)
In accordance with JIS Z8741 (1997), the gloss value at an incident angle of 60° on the uneven surface of the transparent article of each test example was measured. The gloss value is a value measured including light reflected from the back surface (the surface opposite to the uneven surface). The results are shown in the "gloss value" column of Tables 3 and 4.

As shown in Tables 3 and 4, the sparkle value decreases as the surface roughness Sq (Sq [≧20 μm]) measured at a lateral spatial period of 20 μm or more decreases. FIG. 4 is a graph showing the relationship between the value of Sq [≧20 μm] and the sparkle value. As shown in the graph of FIG. 4, when the value of Sq [≧20 μm] is between 50 and 55 nm, the sparkle value is significantly reduced, and when the value of Sq [≧20 μm] is at least 50 nm or less , resulting in a transparent article with a low sparkle value. Also, when the value of Sq [≧20 μm] is between 26 and 30 nm (especially between 26 and 27 nm), the sparkle value is significantly reduced, and the value of Sq [≧20 μm] is at least 26 nm or less. It can be seen that the case results in transparent articles with even lower sparkle values. Sensory evaluation also yielded results indicating that sparkle was strongly suppressed when the value of Sq[≧20 μm] was 50 nm or less and when the value of Sq[≧20 μm] was 26 nm or less. rice field.

Further, as shown in Table 3, in Test Examples 1 to 9 in which the value of surface roughness Sq (Sq[All]) measured without filtering was 50 nm or more, the gloss value was 100% or less, and the reflection was It can be seen that the suppressing effect of In particular, Test Examples 4 to 9, in which Sq [≧20 μm] is 50 nm or less and sparkle is suppressed, are useful as transparent articles having an antiglare surface.

In addition, as shown in Tables 3 and 4, the surface roughness Sq (Sq [≧20 μm]) measured at a lateral spatial period of 20 μm or more, in which sparkle is strongly suppressed, is 26 nm or less. Among the examples, Test Examples 10 and 12 to 16, in which the value of surface roughness Sq (Sq[All]) measured without filtering is less than 50 nm, has a gloss value of 100% or more, and has a rough surface. A glossy texture is obtained while the tactile sensation is imparted by the uneven surface. Therefore, Test Examples 10 and 12 to 16 are particularly useful as transparent articles having a surface that improves writing comfort.

As a reference, the ratio of the surface roughness Sq measured with a lateral spatial period of 40 μm or more to the surface roughness Sq measured with a lateral spatial period of 20 μm or less (Sq [≧40 μm]/Sq [≦ 20 μm]) and the sparkle value is shown in FIG. The above surface roughness Sq ratio is a parameter used in Patent Document 1 to specify an anti-glare surface in which sparkle is suppressed. From the graph shown in FIG. 5, it is not possible to find a strong correlation or a significant decrease in the sparkle value when the surface roughness Sq ratio is within a specific range. This result suggests that the surface roughness Sq ratio has an inappropriate range (for example, 0.70 or less) as a parameter for specifying an uneven surface on which sparkle is suppressed.

DESCRIPTION OF SYMBOLS 10... Transparent article, 11... Transparent base material, 12... Uneven layer, 12a... Uneven surface.

Claims (2)

A transparent article comprising a transparent substrate and a rough uneven surface provided on at least one surface of the transparent substrate ,
The uneven surface has a surface roughness Sq of 5 nm or more and 26 nm or less measured at a lateral spatial period of 20 μm or more, and a surface roughness Sq of 26 nm or more and less than 50 nm measured without filtering. and transparent articles. _2. The transparent article according to claim 1 , wherein the uneven surface is composed of an uneven layer containing at least one selected from _SiO2 , _{Al2O3 ,} ZrO2 and _TiO2 .

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