JP2012032441A - Light-diffusing plate for illumination and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-diffusing plate for illumination having high transmittance and a high haze value.SOLUTION: The light-diffusing plate is manufactured by applying a paste prepared by mixing two kinds of glass powder having different dielectric constants from each other, with the difference of the dielectric constant being 1 or more and 10 or less, on a glass substrate and calcining at a calcination temperature of 540°C to 590°C. Thus, a light-diffusing layer is formed on the glass substrate, the light-diffusing layer containing the two kinds of glass components having different dielectric constants from each other, with the difference of the dielectric constant of 1 or more and 10 or less, and having a matrix formed of one glass component and containing the other glass component dispersed in the matrix.

Description

  The present invention relates to an illumination light diffusing plate having a high transmittance and a high light scattering rate (haze value), and a method for producing the same.

  Conventional fluorescent lamps for illumination use a protective cover made of resin to protect the glass tube. However, in vehicles such as the Shinkansen and commuter trains, there is a risk that the resin will burn in the event of a fire and liquefy and dripping, so the use of the resin is restricted by laws relating to the vehicle.

  In recent years, replacement of fluorescent lamps with LEDs has been rapidly progressing from the viewpoint of energy saving and long life for lighting. Since the LED is a point light source and has high directivity, the light is diffused using a light diffusing plate to provide an antiglare effect. An example of this is an LED bulb that can be found in commercials.

  Conventionally, the light diffusing plate is generally made of acrylic or the like.

  On the other hand, examples of the diffusion plate that does not contain any organic substance include opal glass and a glass whose surface is roughened by sandblasting. However, the former has a low transmittance, and the latter damages the glass, so there is a concern that the strength may decrease.

  On the other hand, a technique for producing a light diffusing plate by applying a diffusing layer to a glass plate or the like in relation to heat radiation has been established.

  For example, Patent Document 1 discloses an antiglare glass in which a paste containing a low-melting glass powder and a heat-resistant inorganic filler is applied to at least one surface of a transparent glass plate, and a light-diffusing film is formed by heat treatment. Yes.

JP-A-10-81545

  However, in the antiglare glass, since the inorganic material filler is added, the transmittance is lowered and the haze value is not sufficient.

  Then, an object of this invention is to provide the light diffusing plate for illumination which has a high transmittance and a high haze value.

  In order to solve the above-mentioned problems, the illumination light diffusion plate of the present invention includes two types of glass components having different dielectric constants, one glass component forms a matrix, and the other glass component is dispersed in the matrix. The light diffusing layer thus formed is provided on a glass substrate.

  Moreover, the light diffusion plate for illumination of the present invention includes two types of glass components having different dielectric constants, one glass component is dispersed in a granular form, and the other glass component is formed so as to cover the periphery thereof. The light diffusing layer is provided on the glass substrate.

  Furthermore, the manufacturing method of the light diffusing plate for illumination of this invention forms a light-diffusion layer by apply | coating the paste which mixed two types of glass powders with different dielectric constants on a glass substrate, and baking at a predetermined baking temperature. It is characterized by doing.

  ADVANTAGE OF THE INVENTION According to this invention, the light diffusing plate for illumination which has a high transmittance | permeability and a high haze value can be provided.

The graph which shows the baking temperature dependence of the total light transmittance about the sample a and the glass powder 1 and the glass powder 5 as the raw material. The graph which shows the baking temperature dependence of the haze value about the sample a and the glass powder 1 and the glass powder 5 as the raw material. The SEM photograph which shows the cross section at the time of apply | coating the sample a to a glass substrate and baking at 550 degreeC. The graph which shows the calcination temperature dependence of the total light transmittance about the sample a-sample d. The graph which shows the baking temperature dependence of the haze value about the sample a-the sample d. The graph which shows the baking temperature dependence of the total light transmittance about sample e-1, e-2, e-3, and the glass powder 1 and the glass powder 5 as the raw material. The graph which shows the calcination temperature dependence of the haze value about sample e-1, e-2, e-3, and the glass powder 1 and the glass powder 5 as the raw material. The graph which shows the baking temperature dependence of the total light transmittance about sample f-1, f-2, f-3, and the glass powder 1 and the glass powder 6 as the raw material. The graph which shows the baking temperature dependence of the haze value about sample f-1, f-2, f-3, and the glass powder 1 and the glass powder 6 as the raw material. The SEM photograph which shows the cross section at the time of apply | coating sample f-2 to a glass substrate and baking at 570 degreeC.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have two or more types of glasses having different refractive indices (since the square of the refractive index is proportional to the dielectric constant, the dielectric constant may be used as a parameter). Light is scattered in the film without using inorganic material filler by baking on the surface of plate glass (planar type) or tube glass (including those processed into halves as appropriate) (fluorescent lamp type) by mixing powder. And succeeded in producing a diffusion plate with a diffusion layer having a high transmittance and a high haze and not containing an organic substance, and further observing the fine structure to obtain knowledge and completing the present invention.

  That is, the light diffusion plate for illumination according to a preferred embodiment of the present invention includes two kinds of glass components having different dielectric constants, and one glass component is dispersed in a granular form and the other glass component is covered so as to cover the periphery thereof. Is provided on a glass substrate, and further has the following characteristics.

  First, the difference between the dielectric constants of the two glass components is 1 or more and 10 or less, preferably 2 or more and 8 or less. The reason why the difference in dielectric constant is 1 or more is that if it is less than 1, the haze value falls below 50% and the light scattering effect becomes insufficient, as is apparent from the results of Example 1 described later. It is. Moreover, the reason why it is 10 or less is that when it exceeds 10, the difference in refractive index between particles becomes too large, and light is totally reflected at the interface, which may reduce the transmittance.

  Next, of the two types of glass components, the ratio of the high dielectric constant glass component is 25% or more and 50% or less, preferably 30% or more and 40% or less. 25% or more and 50% or less is less than 25%, the effect of adding a glass component having a high dielectric constant is not sufficiently exhibited, and when it exceeds 50%, it is also apparent from the results of Examples 2 and 3 described later. This is because the optical characteristics such as the haze value become unstable.

  Furthermore, the average particle size of the two types of glass components is preferably 1 μm or more. The reason why the thickness is 1 μm or more is that if it is less than 1 μm, the specific surface area of the glass becomes too large, and the binder may be insufficiently baked when the paste is baked and baked onto the substrate. Moreover, it is preferable that the average particle diameter of a glass component is 1/4 or less of a film thickness. This is because if the average particle diameter exceeds 1/4 of the film thickness, mixing of different types of glass in the glass layer becomes insufficient and haze may be reduced.

  The light diffusion plate for illumination according to this embodiment is a baking temperature of 540 ° C. to 590 ° C., preferably 550 ° C. to 580 ° C., after applying a paste obtained by mixing two kinds of glass powders having different dielectric constants on a soda lime glass substrate. It can be manufactured by firing at a firing temperature of ° C. to form a light diffusion layer.

  The firing temperature of 540 ° C. to 590 ° C. is that if the temperature is less than 540 ° C., the firing becomes insufficient and the strength of the light diffusion layer does not increase. This is because there is a possibility that the interface between different glass components decreases due to the flow of haze and the haze value decreases.

  Moreover, it is preferable that the softening point of two types of glass powder is 530 degreeC or more and 600 degrees C or less. When the temperature is lower than 530 ° C., the softening point of the glass powder is exceeded in relation to the firing temperature, and the interface between different glass components decreases due to the flow of the glass component, resulting in a decrease in haze value. This is because there is a possibility that if the temperature exceeds 600 ° C., the glass substrate itself may be deformed.

  Hereinafter, the present invention will be described in more detail by way of examples.

(Production and characteristic evaluation of each glass powder)
Prepare glass powder 1 to glass powder 6 having the composition shown in Table 1, and measure transition point (Tg), softening point (Ts), dielectric constant (ε), refractive index, linear expansion coefficient (α), and average particle size. did.

  As for the transition point (Tg) and softening point (Ts), about 50 mg of glass powder is packed in a platinum cell, and a differential thermal analyzer (for example, manufactured by Rigaku Corporation) at a temperature rising rate of 10 ° C./min up to 800 ° C. TG8110), the first inflection point was the transition point (Tg), and the fourth inflection point was the softening point (Ts).

  Regarding the dielectric constant (ε), the glass powder was remelted and formed into a plate shape and then processed to obtain a measurement sample having a diameter of 45 mm × thickness of 3 mm. Aluminum electrodes were formed on both surfaces of the measurement sample by vapor deposition, and the relative dielectric constant at a frequency of 1 MHz was measured using an LCR meter (for example, LF IMPEADANCE ANALYZER 4192A manufactured by HP).

  Furthermore, regarding the linear expansion coefficient (α), after the glass powder was pressure-molded, the fired body obtained by firing for 10 minutes at a temperature 30 ° C. higher than Ts was processed into a cylindrical shape having a diameter of 5 mm and a length of 2 cm. The average linear expansion coefficient at 50 to 350 ° C. was measured with an dilatometer (eg, TMA8310 manufactured by Rigaku Corporation).

  Moreover, about the average particle diameter, the average particle diameter D50 was measured on condition of the following using the laser diffraction type particle size distribution measuring apparatus HEROS & RODOS (made by SYMPATEC, Germany).

Glass powder weight: about 0.1-0.2 g (sample concentration standard 2-15%), lens focal length: 20 mm, dispersion method: automatic dry dispersion unit RODOS / M, dispersion pressure: 1.5 bar
Further, the refractive index is obtained by calculating from the value of molar refraction described in “A-A Appen Glass Chemistry (1974)” as a reference.

These results are shown in Table 2.

  Next, glass samples having different dielectric constants were combined to produce a glass sample.

[Effect of difference in dielectric constant on characteristics of light diffusion plate]
(Sample preparation)
As a combination of glass powders having different dielectric constants, as shown in Table 3, sample a (glass powder 1: glass powder 5 = 1: 1, dielectric constant difference 3.3), sample b (glass powder 2: glass powder 5) = 1: 1, dielectric constant difference 2.2), sample c (glass powder 3: glass powder 5 = 1: 1, dielectric constant difference 1.1), sample d (glass powder 4: glass powder 5 = 1: 1) 4 types of dielectric constant difference 0.6) were prepared.

(Production and characteristic evaluation of light diffusion plate)
Each sample is mixed with an organic vehicle appropriately combined with a solvent such as terpineol and butyl carbitol acetate, and various resins, etc., and a paste is prepared. It apply | coated to the film thickness of about 50 micrometers on the glass substrate.

  After applying the paste, this was dried, further held in a heating furnace at a temperature of 540 to 590 ° C. for 30 minutes, and then cooled to obtain a light diffusion plate.

  About the obtained light diffusing plate, the total light transmittance and the light scattering rate (haze value) were calculated | required by Suga Test Instruments company haze meter HZ-1.

  First, regarding the sample a and the glass powder 1 and the glass powder 5 as the raw materials, the dependency of the total light transmittance on the firing temperature is shown in FIG. 1, and the dependency of the haze value on the firing temperature is shown in FIG.

  From this, it was found that in sample a, the total light transmittance did not change much as compared with glass powder 1 and glass powder 5, but the haze value was extremely high over the entire range between 540 and 590 ° C.

  In FIG. 3, the SEM photograph of the cross section at the time of apply | coating the sample a to a glass substrate and baking at 550 degreeC is shown.

  From FIG. 3, the fired film of sample a has two parts with different contrasts, the light color part is a part derived from glass powder 5 (glass 5 part), and the dark color part is a part derived from glass powder 1 ( 1 part of glass).

  From this, the glass powder 5 having a low softening point flows during firing to form a matrix, and more specifically, a structure in which a portion derived from the glass powder 1 having a high softening point is dispersed in the matrix, When the portion derived from the glass powder 5 having a low softening point flows and forms a structure covering the periphery of the portion derived from the glass powder 1 having a high softening point dispersed in a granular form, the interface between the glass 1 portion and the glass 5 portion. It is inferred that the degree of light scattering at the point of time increases and the haze value improves.

  Next, regarding samples a to d, the dependency of the total light transmittance on the firing temperature is shown in FIG. 4, and the dependency of the haze value on the firing temperature is shown in FIG.

  Accordingly, at any firing temperature between 550 ° C. and 580 ° C., the haze value decreases as the difference from the dielectric constant of the two kinds of glass powders combined decreases from sample a to sample d. I found out. Moreover, also in the structure | tissue observation by SEM, it became difficult to see the grain boundary of glass as the difference of the dielectric constant of two types of combined glass powder became small.

  From the above, it is better that the difference in dielectric constant of the glass powder to be combined is larger, and the difference is 1 or more, preferably 2 or more. The reason why the difference is set to 1 or more is that if the difference is less than 1, as shown in FIG. 5, the haze value is less than 50% and the light scattering effect becomes insufficient.

  Next, the effect of the mixing ratio of glass powders having different dielectric constants on the characteristics of the light diffusion plate was examined.

[Effect of mixing ratio on characteristics of light diffusion plate]
(Sample preparation)
As a combination of glass powders having different dielectric constants, as shown in Table 4, glass powder 1 and glass powder 5 were used as sample e (dielectric constant difference 3.3).

Further, as to sample e, samples e-1, e-2, and e-3 were prepared in which the mixing ratio of glass powder 1 and glass powder 5 was changed to three types as shown in Table 5.

(Production and characteristic evaluation of light diffusion plate)
Samples e-1, e-2, e-3 were mixed with an organic vehicle appropriately combined with a solvent such as terpineol and butyl carbitol acetate, various resins, etc., as in Example 1, to prepare a paste. Was applied on a soda lime glass substrate to a film thickness of about 50 μm by an appropriate application means such as spin coating, blade coating, screen printing or the like.

  After applying the paste, this was dried, further kept in a heating furnace at a temperature of 550 to 600 ° C. for 30 minutes, and then cooled to obtain a light diffusion plate.

  About the obtained light diffusing plate, the total light transmittance and the light scattering rate (haze value) were calculated | required by Suga Test Instruments company haze meter HZ-1.

  Regarding samples e-1, e-2, e-3, and glass powder 1 and glass powder 5 as raw materials thereof, the dependency of total light transmittance on the firing temperature is shown in FIG. 6, and the dependency of haze value on the firing temperature is shown. 7 shows.

  From this, it was found that the transmittance does not show a clear tendency due to the difference in the samples, but the haze value of Sample e-1 rapidly decreases as the firing temperature is increased. This is presumably because the glass 1 was dissolved in the glass 5 during firing.

  On the other hand, in e-2 and e-3 in which the glass powder 1 is a combination of 50% or more, the haze is kept high even at high temperature firing.

  From the above, it is considered that when the ratio of the glass powder 5 which is a glass having a high dielectric constant is 50% or less, the optical characteristics such as the haze value are stabilized and the margin for the firing condition is wide.

[Effect of mixing ratio on characteristics of light diffusion plate]
(Sample preparation)
As a combination of glass powders having different dielectric constants, as shown in Table 4, glass powder 1 and glass powder 6 were used as sample f (dielectric constant difference 3.2).

Furthermore, as for sample f, samples f-1, f-2, and f-3 were prepared in which the mixing ratio of glass powder 1 and glass powder 6 was changed to three types as shown in Table 6.

(Production and characteristic evaluation of light diffusion plate)
Samples f-1, f-2, and f-3 were mixed with an organic vehicle in which solvents such as terpineol and butyl carbitol acetate, various resins, and the like were appropriately combined in the same manner as in Example 1 to prepare a paste. Was applied on a soda lime glass substrate to a film thickness of about 50 μm by an appropriate application means such as spin coating, blade coating, screen printing or the like.

  After applying the paste, this was dried, further kept in a heating furnace at a temperature of 550 to 600 ° C. for 30 minutes, and then cooled to obtain a light diffusion plate.

  About the obtained light diffusing plate, the total light transmittance and the light scattering rate (haze value) were calculated | required by Suga Test Instruments company haze meter HZ-1.

  Regarding samples f-1, f-2, and f-3, and glass powder 1 and glass powder 6 as raw materials thereof, FIG. 8 shows the firing temperature dependence of the total light transmittance, and the firing temperature dependence of the haze value. 9 shows.

  From this, it was found that the transmittance does not show a clear tendency due to the difference in the samples, but the haze value of Sample f-1 rapidly decreases as the firing temperature is increased. This is presumably because the glass 1 was melted into the glass 6 during firing.

  On the other hand, in f-2 and f-3 in which the glass powder 1 is a combination of 50% or more, the haze is kept high even at high temperature firing.

  In addition, in f-2 and f-3 in which the ratio of the glass powder 1 is 50% or more, in the case of firing at 550 ° C., there is a concern that the transmittance may decrease due to insufficient firing. Firing is preferred.

  From the above, it can be considered that when the ratio of the glass powder 6 which is a glass having a high dielectric constant is 50% or less, the optical characteristics such as the haze value are stabilized and the margin for the firing condition is wide.

  FIG. 10 shows an SEM photograph of a cross section when the sample f-2 is applied to a glass substrate and fired at 570 ° C.

  From FIG. 10, the fired film of sample f-2 has two parts with different contrasts, the light color part is derived from the glass powder 6 (glass 6 part), and the dark color part is derived from the glass powder 1 Presumed to be a part (glass 1 part).

  As a result, the glass powder 6 having a low transition point flows during firing to form a matrix, and a structure in which the portion derived from the glass powder 1 having a high transition point is dispersed in the matrix results in the glass 1 part and the glass 6. It is presumed that the degree of light scattering at the interface of the portion is increased and the haze value is improved.

Claims (9)

  A glass substrate is provided with a light diffusing layer containing two glass components having different dielectric constants, one glass component forming a matrix, and the other glass component being dispersed in the matrix. A light diffusion plate for illumination.   Provided on the glass substrate a light diffusing layer containing two types of glass components having different dielectric constants, wherein one glass component is dispersed in a granular form and the other glass component is formed so as to cover the periphery of the glass component. A light diffusion plate for illumination.   The illumination light diffusing plate according to claim 1 or 2, wherein a difference in dielectric constant between the two types of glass components is 1 or more and 10 or less.   4. The illumination light diffusion plate according to claim 1, wherein, of the two types of glass components, a ratio of a glass component having a high dielectric constant is 25% or more and 50% or less. 5.   5. The light diffusion plate for illumination according to claim 1, wherein an average particle diameter of the two kinds of glass components is 1 μm or more and ¼ or less of a fired film thickness.   The light diffusion plate for illumination according to any one of claims 1 to 5, wherein a haze value is 50% or more.   A method for producing a light diffusing plate for illumination, wherein a light diffusion layer is formed by applying a paste in which two kinds of glass powders having different dielectric constants are mixed on a glass substrate and then baking the paste at a predetermined baking temperature. .   The said baking temperature is 540 degreeC-590 degreeC, The manufacturing method of the light diffusing plate for illumination of Claim 7 characterized by the above-mentioned.   The method for producing an illumination light diffusing plate according to claim 7 or 8, wherein the softening point of the two types of glass powder is 530 ° C or higher and 600 ° C or lower.