JP2009042499A - Light diffusive thin film formed on translucent substrate, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusive thin film having both a high haze value and a high total light transmittance. <P>SOLUTION: The light diffusive thin film is a light diffusive thin film formed on a translucent substrate, the thin film is dotted with dome-like or spherical protruded parts on the translucent substrate, the protrusions is baked at a temperature higher by 0-30°C than a softening point temperature of glass forming glass powder in the glass powder having 4-10 μm of average particle size, and is formed on the translucent substrate having both the high haze value and the high total light transmittance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-diffusing thin film formed on a light-transmitting substrate and having a light diffusibility.

  The translucent base material having a fine uneven structure on the surface shape diffuses light due to the uneven structure, so that it imparts antiglare properties to the display element and utilizes diffusion of light that is transmitted or reflected. It is used as a light diffusing material in applications and the like in order to lower the visibility of screens and fluoroscopic images.

  In Patent Document 1, in order to give a light diffusing function to a translucent base material, a paste containing a low-melting glass powder and an inorganic filler having an average particle size of 2 μm or less is applied to the base material and fired. Thus, a light diffusing thin film having a surface roughness (Ra) of 0.4 μm or less is formed.

Patent Document 2 discloses a dielectric that becomes a glass film with a Ra of 0.2 μm or less when a dielectric green sheet formed containing a low-melting glass powder is fired at a temperature 10 ° C. higher than the softening point of glass. A forming glass powder is disclosed.
JP-A-10-81545 JP 2006-89374 A

  When using a light diffusive thin film for a display element, for example, when using it as a thin film for imparting anti-glare properties to a display, or as a screen reflecting an image from a projector, not only light diffusibility but also transmitted light In particular, it is desired that visible light transmission is high. An object of the present invention is to provide a light diffusing thin film having a high haze value and total light transmittance.

  The light diffusive thin film formed on the light transmissive substrate of the present invention is a light diffusible thin film formed on the light transmissive substrate, and the thin film has a dome-shaped or spherical convex portion that is light transmissive. The convex portions are scattered on the base material, and the convex portion has an average particle size of 0.4 to 10 μm, preferably 2 to 8 μm, and the glass powder is 0 to the softening point temperature of the glass forming the glass powder. It is characterized by being fired at a temperature 30 ° C, preferably 5-30 ° C higher.

  The thin film is formed such that convex portions capable of diffusing visible light are scattered on a translucent substrate. The portion without the convex portion is a so-called vacant state and does not hinder the transmission of light. Therefore, the shape of the convex portion is a dome shape or a spherical shape, and the convex portion has a glass powder having an average particle size of 0.4 to 10 μm, preferably 2 to 8 μm, to form the glass powder. By baking at a temperature 0 to 30 ° C., preferably 5 to 30 ° C. higher than the softening point temperature, a light diffusive thin film having a high haze value and total light transmittance can be achieved.

  About the shape of the said convex part, when the adhesiveness with a translucent base material is considered, the thing of a dome shape is more preferable.

  In addition, the average particle diameter of this invention is defined as a thing of the median diameter (particle diameter in 50% volume frequency distribution) calculated | required by the laser diffraction scattering method.

  A suitable paste for obtaining the thin film contains 1 to 35% by weight, preferably 7 to 33% by weight of glass powder having an average particle size of 0.4 to 10 μm, preferably 2 to 8 μm. It is preferable to do.

  The light diffusive thin film preferably has a paste containing 1 to 35% by weight, preferably 7 to 33% by weight of glass powder having an average particle size of 0.4 to 10 μm, preferably 2 to 8 μm. The step of adjusting, the step of applying the paste to the translucent substrate, and the translucent substrate coated with the paste at 0 to 30 ° C., preferably 5 than the softening point temperature of the glass forming the glass powder. It is preferable to have a process of heating at a temperature higher by 30 ° C.

  And it is preferable to make application | coating thickness of a paste equivalent to the average particle diameter of glass powder. Here, “equivalent” refers to a state in which the glass powder is applied so that the glass powder is not stacked in the direction opposite to the substrate surface when the light-transmitting substrate surface is used as a reference surface. ing.

  By making the coating thickness of the paste equal to the average particle diameter of the glass powder, it is preferable that the vacancies as described above can be easily formed in the thin film portion only by the diffusion of components other than the glass powder of the paste.

  The light diffusing thin film of the present invention has a surface roughness of preferably 0.1 to 0.6 μm, more preferably 0.2 to 0.5 μm. The haze value is preferably 35 to 70%, more preferably 45 to 65%, and the total light transmittance is preferably 80 to 95%, more preferably 85% to 95%. Since both the total light transmittance is high and the 60 ° specular gloss has a value of 45 to 60, when the light diffusive thin film is used for a display element, for example, to impart an antiglare property to the display. This is particularly effective when used as a thin film or a screen reflecting an image from a projector.

  The suitable example of the light diffusible thin film formed on the translucent base material of this invention is demonstrated using drawing. FIG. 1 is a diagram for explaining a main part of a cross section of a thin film formed with a dome-shaped convex part 31, and FIG. 2 is a diagram for explaining a main part of a cross section of the thin film formed with a spherical convex part 32. It is. In FIG. 1 and 2, between the translucent base material 2 and a dashed-dotted line is the light diffusable thin film 1 of this invention. In addition, between the said dashed-dotted line is drawn in the figure for the aid of an understanding, and does not exist in an actual thin film.

  FIG. 3 is a diagram for explaining a state when the paste 6 is applied to the translucent substrate 2. The paste 7 has a glass powder 7 and a solvent 7. The vacancy 4 is formed by the evaporation of the solvent 7. When the glass powder 5 is heated at a temperature equal to or higher than the softening point temperature of the glass forming the glass powder 5, the glass is in a softened state, and the glass powder 7 is bonded to the translucent substrate 2 and the glass powder 5. As a result, a convex portion 31 or 32 is formed.

  The translucent substrate 2 is preferably a plate-shaped glass substrate such as soda lime silicate glass, borosilicate glass, aluminosilicate glass, barium borosilicate glass, or quartz glass. In particular, a glass substrate produced by a float process is preferable. Furthermore, these glass substrates include clear glass products, colored glass products such as green and bronze, functional glass products such as UV and IR cut glass, safety glass products such as tempered glass, semi-tempered glass, and laminated glass. Can be used.

  As the thickness of the substrate, for example, a glass substrate having a thickness of 0.1 to 10 mm can be used. In particular, from the viewpoint of balance between strength and weight of glass, a glass substrate having a plate thickness of 0.1 to 3 mm is preferable for use as a display device.

  The glass forming the glass powder 5 is preferably a glass composition formed on the basis of any one of silicon oxide, boron oxide, zinc oxide, bismuth oxide, lead oxide, and phosphorus oxide. The glass preferably has a softening point temperature in the range of 300 to 700 ° C, preferably 350 to 650 ° C. In general, a glass having a low softening point temperature tends to have a low strength. On the other hand, when the softening point temperature is high, the production cost of the light diffusive thin film tends to be high. Further, the translucent substrate may be deformed.

Incidentally, the softening point temperature in the present invention refers to a temperature at which the viscosity of the glass is 10 ^7.6 poise.

  The glass powder 5 is formed by pulverizing a block of glass by a method such as wet or dry pulverization so as to have a predetermined average particle size. Then, the paste 6 is obtained by mixing with the solvent 7. As the solvent 7, a general-purpose paste solution can be used. For example, a paste solution having at least one selected from α-terpineol, butyl carbitol acetate, polyethylene glycol, silicone oil, and the like may be used.

  Moreover, it is preferable that the solvent 7 has cellulose, such as ethyl cellulose, methylcellulose, and nitrocellulose, as a component which can become the binder of the glass powder 5.

  The paste 6 is applied to the translucent substrate 2 by a known application method. Examples of the method include screen printing, brush coating, flow coating, spin coating, and the like, which can be appropriately selected in consideration of the viscosity and productivity of the paste.

Hereinafter, the present invention will be described in more detail with reference to examples.
1. Preparation of paste Fine silica sand as SiO ₂ source, boric acid as B ₂ O ₃ source, zinc oxide as ZnO source, lithium carbonate as Li ₂ O source, sodium carbonate as Na ₂ O source, K ₂ O source as K ₂ O source Potassium carbonate, cupric oxide as the CuO source, manganese dioxide as the MnO ₂ source, magnesium carbonate as the MgO source, calcium carbonate as the CaO source, strontium carbonate as the SrO source, barium carbonate as the BaO source, Bi Bismuth oxide was required as a ₂ O ₃ source. These were prepared as much as possible in a desired glass composition, and then put into a platinum crucible and heated and melted in an electric heating furnace at 1000 to 1300 ° C. for 1 to 2 hours to obtain glasses A, B and C. Table 1 shows the composition and softening point temperature of each glass.

  The glass was formed into a cullet shape with a roll molding machine, and sized with a pulverizer so that the powder had an average particle size of 0.4 to 10 μm. The average particle diameter of the glass was measured by a laser diffraction method.

  Next, a paste solution consisting of α-terpineol and butyl carbitol acetate, a solvent consisting of ethyl cellulose and the glass powder were mixed to prepare a paste.

  Table 2 shows the glass type used in each Example, the average particle diameter of the glass powder, and the content of the glass powder in the paste.

2. Production of translucent base material on which light diffusing thin film is formed Soda lime silicate glass by a rectangular float method having a length of 370 mm, a width of 470 mm and a thickness of 0.7 mm is used as a base material, and the paste is screened on the base material. After printing, the substrate was heated at the temperature shown in Table 3 for 3 minutes to obtain a translucent substrate on which a light diffusible thin film was formed.

3. Evaluation of translucent base material on which light diffusive thin film was formed The following evaluation was performed on the samples of each Example and Comparative Example. The evaluation results are shown in Table 4. The light diffusing thin film obtained by the present invention had no abnormal protrusions, and was excellent in both haze value and total light transmittance.

3.1. Observation of thin film surface The thin film was visually and manually palpated to determine whether the thin film had abnormal protrusions.

3.2. Measurement of Surface Roughness The surface shape of the thin film was measured in a 100 μm × 100 μm in-plane shape with a stylus type surface scanner (SURFCORDER ET4000A; manufactured by Kosaka Laboratory). Height data was acquired in increments of 1 μm, and a total of 10,000 points of height data was acquired in a 100 μm × 100 μm plane. The arithmetic average surface roughness Ra value obtained from this acquired data in accordance with “JIS B0601 (2001)” was defined as the surface roughness value.

3.3.60 ° Specular Glossiness In accordance with the method described in JIS-Z8741 (1997), the back surface of the glass substrate is black using a Nippon Denshoku specular glossiness measuring machine (Σ80 COLOR MEASURING SYSTEM VGS). After applying the paint and performing antireflection treatment on the back surface, the 60 ° specular gloss at the center point of the sample was measured.

3.4. Measurement of haze value Based on JIS-R3212 (1998), it measured using Nippon Denshoku NDH2000.

3.5. Measurement of total light transmittance Using a spectrophotometer [U-4000; Hitachi, Ltd.], the total light transmittance was measured in accordance with the provisions of JIS K 7361 (1997).

The figure explaining the principal part of the cross section of the thin film in which the dome-shaped convex part 31 is formed. It is a figure explaining the principal part of the cross section of the thin film in which the spherical convex part 32 is formed. It is a figure explaining a state when the paste 6 is apply | coated to the translucent base material 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light diffusable thin film 2 Translucent base material 31 Dome-shaped convex part 32 Spherical convex part 4 Vacancy in thin film 5 Glass powder 6 Paste 7 Solvent

Claims (4)

A light-diffusing thin film formed on a light-transmitting substrate, the thin film having dome-shaped or spherical protrusions scattered on the light-transmitting substrate, and the protrusions having an average particle size of 0 .4-10 μm glass powder was formed on a translucent substrate characterized by being fired at a temperature 0-30 ° C. higher than the softening point temperature of the glass forming the glass powder. Light diffusive thin film. The paste for forming the light diffusable thin film formed on the translucent base material of Claim 1 which contains 1-35 weight% of glass powders with an average particle diameter of 0.4-10 micrometers. A method for producing a light diffusing thin film formed on a light-transmitting substrate, the method comprising preparing a paste containing 1 to 35% by weight of glass powder having an average particle size of 0.4 to 10 μm, It has the process of apply | coating to a translucent base material, and the process of heating the translucent base material with which the paste was apply | coated at the temperature 0-30 degreeC higher than the softening point temperature of the glass which forms glass powder. The manufacturing method of the light diffusable thin film formed on the translucent base material in which the dome-shaped or spherical convex part to be said is dotted. 4. The method for producing a light diffusive thin film formed on a translucent substrate according to claim 3, wherein the thickness of the paste applied is equal to the average particle diameter of the glass powder.

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