JP2013035745A - Light diffusion glass member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light diffusion glass member which has sufficient surface strength without roughening the glass surface, and has a flat transmittance property in the wide range exceeding the visible range.SOLUTION: The member includes a crystal phase in glass, and includes, in wt.% in terms of oxide, 35-70% SiO, 0-8.0% AlO, 15-35% BO, 3-10% of components in total selected from NaO, KO, and LiO, 6-20% in total of components selected from CaO and YO, and 0-1% SbO. The member has a total light beam average transmittance is 5-50% for wavelengths of 400-2,500 nm as evaluated using a member of a thickness of 2.0 mm, and the average value of the transmittance deviation to the total light beam average transmittance is 4.0% or less in the wavelength region of 400-2,500 nm.

Description

  The present invention relates to a light diffusing glass member having flat transmittance characteristics over a wide wavelength range exceeding the visible range.

  A glass member may be used as a light diffusing material for a lighting fixture or an optical machine. As such a light diffusing glass member, a film forming method for forming an appropriate milky white film on the glass surface by sputtering or vacuum deposition, and a sand blasting method in which hard sand is blown against the glass surface with compressed air are known. A method of etching the glass surface after blasting with hydrogen fluoride is also known.

Japanese Patent Laid-Open No. 07-010605 JP 2011-032124 A JP 2010-287791 A JP 2011-077718 A

  However, the configuration in which the glass surface is roughened like the sand blast method has a problem that the same optical characteristics cannot be realized on the entire glass surface. In addition, dirt easily adheres to the glass surface, and certain optical characteristics cannot be maintained over time. On the other hand, when the film forming method is employed, there is a problem that the surface hardness is insufficient and the surface is easily damaged.

  Here, although a method using crystallized glass is known, an inexpensive glass composition having a desired transmittance and a flat transmittance characteristic in a wide range exceeding the visible range, and such No suitable method for producing crystallized glass using a glass composition is known.

  The present invention has been made in view of the above problems, and has sufficient surface strength without roughening the glass surface, and flat transmittance characteristics over a wide range exceeding the visible range. It aims at providing the light-diffusion glass member which has, and its manufacturing method.

In order to achieve the above object, the light diffusing glass member according to the present invention has a crystal phase in the glass, and is expressed by 35% to 70% of SiO ₂ and 0 to Al ₂ O ₃ in terms of weight% in terms of oxide. _~8.0%, B 2 _{O 3} and _{15~35%, Na 2 O, K} 2 O, 3~10% across a component selected from Li ₂ O, is selected _CaO, from Y 2 _{O 3} 6-20% of the total ingredients, and
Sb ₂ O ₃ is contained in an amount of 0 to 1%, and is evaluated by a member having a thickness of 2.0 mm. The total light average transmittance is 5 to 50% with respect to a wavelength of 400 nm to 2500 nm. The average value of the transmittance deviation with respect to the average transmittance is 4.0% or less in the wavelength region of 400 nm to 2500 nm. The numerical range is a concept including the lower limit and the upper limit.
The inventors' research has first confirmed that Al ₂ O ₃ and CaO are effective as components for controlling the transmittance, but Y ₂ O ₃ and ZnO are also involved in crystallization. It was confirmed that the transmittance can be controlled by the content. Here, CaO and Y ₂ O ₃ may be selectively used as in Examples 1 to 3 and Example 5, or may be used in combination as in Example 4.
In any case, the preferable content of CaO is 6 to 20%, and the preferable content of Y ₂ O ₃ is 6 to 15%. Since Y ₂ O ₃ has an effect of reducing the transmittance, more preferably, the content should be 10% or less in order to maintain a predetermined transmittance. Further, when used in combination CaO and _Y 2 _{O 3} is a CaO 1.0 to _20%, preferably contained in a range of Y 2 _{O 3} and 1.0 to 15%. Incidentally, to control the transmittance by increasing or decreasing the content of CaO, the addition of Y ₂ O ₃ can improve chemical durability.
However, since the glass becomes unstable when a large amount of these are used, the total amount of CaO + Y ₂ O ₃ should preferably be 6 to 12% (more preferably 8 to 10%).
Further, preferably, 0 to 10% of ZnO should be further contained, and the transmittance can be reduced by adding ZnO. In addition, by adding 0 to 1% of the F component, the chemical durability performance is improved, and the viscosity of the glass is reduced.

Also, preferably, the SiO ₂ 48~62% (more preferably, 52 to _58%), the B 2 _{O 3} 20~30% (more preferably, 22 to 28%), the _Sb 2 _{O 3} 0. It should be 1-0.5% (more preferably 0.2-0.4%).

By the way, for example, when Y ₂ O ₃ or ZnO is not included, Al ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, and CaO are contained corresponding to the required transmittance. The amount is increased or decreased accordingly. Specifically, when it is desired to increase the transmittance, the content of Al ₂ O ₃ or CaO may be reduced. Further, the transmittance can be increased by increasing the content of Na ₂ O or K ₂ O. On the other hand, when it is desired to reduce the transmittance, Al ₂ O ₃ or CaO may be increased.

However, Al ₂ O ₃ is 0.5 to 4% (more preferably 1 to 3%), Li ₂ O + Na ₂ O + K ₂ O is 4 to 8% (more preferably 5 to 7%) in total, and CaO is , 7 to 15% (more preferably, 8 to 12%). It is also possible to add ZrO ₂ 0-5 wt% to enhance the chemical durability.

  The total light average transmittance is calculated by measuring the spectral transmittance according to JIS Z 8722 for a wavelength range of 400 nm to 2500 nm. Further, a light diffusion glass member whose front and back surfaces are polished and finished to a thickness of 2 mm ± 0.1 mm is used as a measurement sample.

The light diffusing member according to the present invention has a flat transmittance characteristic over a wide wavelength range. However, when the above-described preferable composition is adopted, when the light diffusing member is evaluated in a wavelength region of 400 nm to 2500 nm, all light rays in the region are used. The average value of the transmittance deviation with respect to the average transmittance can be 3.0% or less.
Moreover, when evaluating in the area | region of wavelength 400nm-2500nm, the transmittance | permeability deviation with respect to the total light average transmittance | permeability in the area | region can be 10% or less.

  The light diffusing member according to the present invention is realized by crystallized glass, and includes a first step of melting the glass raw material, a second step of forming the molten glass, and a third step of gradually cooling the formed glass. And a fourth step of continuously heating the shaped glass after slow cooling at a heating temperature of 730 ° C. to 850 ° C. for 8 hours to 30 hours.

  When the heating temperature is lower than 730 ° C. in the fourth step, flat transmittance characteristics cannot be realized even if the heating time is increased.

  FIG. 1 illustrates the change in transmittance characteristics due to the difference in heating temperature in the fourth step for glasses having the same composition included in the scope of the present invention. All heating times are 10 hours. As shown in the drawing, when the heating temperature is about 650 ° C., 675 ° C., and 700 ° C., the crystallization is insufficient and the transmittance greatly varies depending on the wavelength.

  On the other hand, in the region where the heating temperature is 750 ° C., 800 ° C., and 850 ° C., a flat transmittance characteristic can be realized. Note that the experimental result at the heating temperature of 880 ° C. indicates that flat transmittance control cannot be realized at a heating temperature higher than the heating temperature of 850 ° C.

  2 and 3 illustrate changes in transmittance characteristics due to differences in the heat treatment time of the fourth step for glasses having the same composition included in the scope of the present invention. All heating temperatures are 750 ° C. As shown in the figure, when the heating time is about 1 to 3 hours, crystallization is insufficient and the transmittance largely varies depending on the wavelength.

  On the other hand, when the heating time is about 10 hours, 20 hours, and 30 hours, flat transmittance characteristics can be realized. Although not shown, there is no change in performance even when the heating time is 30 hours or longer, and it has been confirmed from the experimental results (not shown) that the heating time should be 8 hours to 30 hours.

  In the fourth step of the present invention, it is sufficient to continuously heat at a heating temperature of 730 ° C. to 850 ° C. for 8 hours to 30 hours. Therefore, it is not always necessary to maintain a constant heating temperature, and the maximum heating temperature is maintained. It is also preferable to increase the heating temperature stepwise.

  Similarly, after the heating time of 8 hours to 30 hours has elapsed, it is preferable to provide a slow cooling step. In this case, mechanical strength in the subsequent steps such as cutting and polishing can be ensured. However, it has been confirmed that there is no difference in optical characteristics such as transmittance even when the slow cooling step is not provided.

  According to the above-described present invention, it is possible to realize a light diffusion glass member having a flat glass surface and having flat transmittance characteristics in a wide range exceeding the visible range. And the light-diffusion glass member of this invention can be used conveniently for the light-diffusion plate of a display apparatus, the light-diffusion plate of various measuring devices, the light-diffusion plate, cover of various illuminations, etc.

It is drawing which shows the relationship between heat processing temperature and a total light transmittance. It is drawing which shows the relationship between heat processing time and a total light transmittance. It is another drawing which shows the relationship between heat processing time and a total light transmittance. It is a flowchart which shows the manufacturing method of an Example. It is drawing which shows the total light transmittance about the sample of the composition of Example 1. FIG. It is drawing which shows a total light transmittance about the sample of the composition of Examples 4-5.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, it is not specifically limited. FIG. 4 is a process flow diagram for carrying out the present invention.

First, necessary powder raw materials are weighed and mixed (ST1). The composition used in the experiments shown in FIGS. 1 and 2 is as in Example 1 in the table below. In many experiments in which the composition ratio was changed as in Example 2 to Example 3, such as using Li ₂ O instead of or in addition to Na ₂ O or K ₂ O, FIG. The same tendency as in FIG. 2 is obtained. Incidentally, it can be added to ZrO ₂ 0-5 wt% in order to increase the water resistance is confirmed by the composition of Example 2 and Example 3.

  Subsequently, the mixed powder raw material is melted using an electric furnace or a gas furnace (ST2). In addition, this process is the same as a normal glass manufacturing process, and includes a slow cooling process. Next, the sample that passed the inspection process is embossed according to the shape and size as necessary (ST3).

  Thus, when the process of step ST2 or step ST3 is completed, the glass member is heat-treated and crystallized to be white. In this reheating step, the heating temperature and the heating time are appropriately set within the range of the heating temperature of 730 ° C. to 850 ° C. and the heating time of 8 hours to 30 hours. As shown in FIG. 4, it is preferable to raise the heating temperature stepwise toward the maximum temperature and to provide a slow cooling step.

In any case, when the transmittance is lowered, it is preferable to lower the maximum heating temperature, and when it is desired to increase the transmittance, it is preferable to raise the maximum heating temperature. FIG. 5 shows transmittance curves for Sample 1 having a maximum heating temperature of 800 ° C. and Sample 2 having a maximum heating temperature of 750 ° C. FIG. 4 (b) shows the transition of the heating temperature in producing the sample. In each case, the heating time at the maximum heating temperature is 10 hours, and then a slow cooling step is provided. .
Sample 1 and sample 2 are manufactured in the process shown in FIG. 4B with respect to the material having the composition ratio of Example 1, and only the heat treatment temperatures (800 ° C. and 750 ° C.) are different.
Moreover, it has the following characteristics, and the average value (average deviation) of the transmittance deviation with respect to the average transmittance (28.15% and 20.90%) is 1.18% and 3.02%. The maximum deviation is 7.66% and 6.76%, which is 10% or less.

  When the reheating step (ST4) as described above is completed, it is cut into an appropriate shape as necessary, and the surface is polished and flattened. Note that a film formation step of a thin film such as an antireflection film may be provided.

By the way, in the composition of Examples 1 to 3, CaO is an essential component, but it is also preferable to contain Y ₂ O ₃ instead of or in addition to this. Table 3 shows the compositions of Examples 4 and 5. By containing Y ₂ O ₃ , the transmittance can be lowered over a wide wavelength range (wavelength 400 nm to 2500 nm) without impairing the flat transmittance characteristic.

Moreover, the addition of ZnO in addition to Y ₂ O _3, can be reduced further transmission. In Example 5, CuO is included as a colorant in order to further flatten the transmittance characteristics. Examples of the colorant include CuO and CoO. In any case, the addition amount is 0.1% by weight or less.

  FIG. 6 shows the transmittance curve of the light diffusing glass manufactured through the steps shown in FIG. 4 for the raw materials having the compositions of Example 4 and Example 5. The light diffusing glass is manufactured with a heat treatment temperature of 800 ° C. and a heat treatment time of 10 hours.

  Table 4 summarizes the average transmittance, the average deviation with respect to the average transmittance, and the maximum deviation with respect to the average transmittance for the light diffusing glasses of Example 4 and Example 5. Table 4 shows the characteristics in the visible region (400 to 700 nm) and 400 nm to 2500 nm. The average transmittance in the visible region is 5% or less, and the average transmittance in the 400 nm to 2500 nm is 10% or less. Yes.

  Further, the deviation with respect to the average transmittance is small and the transmittance curve is flat. The maximum deviation in the 400 nm to 2500 nm region is 7% or less, and the maximum deviation in the 400 to 700 nm region is 2% or less. In addition, the average value (average deviation) of the transmittance deviation is 3.5% or less in the 400 nm to 2500 nm region and 0.6% or less in the 400 to 700 nm region.

Claims (6)

It has a crystalline phase in the glass and is expressed as a percentage by weight in terms of oxide.
The SiO ₂ 35~70%,
Al ₂ O ₃ and 0 to 8.0%,
B ₂ O ₃ 15-35%,
3 to 10% in total of components selected from Na ₂ O, K ₂ O, Li ₂ O,
6 to 20% in total of components selected from CaO and Y ₂ O ₃ , and
Comprising 0 to 1% of Sb ₂ O ₃ ,
When evaluated with a member having a thickness of 2.0 mm, the total light average transmittance is 5 to 50% for wavelengths of 400 nm to 2500 nm,
The light diffusion glass member, wherein an average value of a transmittance deviation with respect to the total light average transmittance is 4.0% or less in a wavelength region of 400 nm to 2500 nm.   The light-diffusion glass member of Claim 1 which further contains 1.0-10% ZnO. 6.0 to 15% of _Y 2 _{O 3,} and / or, a 6.0 to 20% of CaO, light diffusing glass member according to claim 1 or 2 containing 6.0 to 12% overall.   The light-diffusion glass member in any one of Claims 1-3 containing F component of less than 1.0%.   3. The light diffusing glass member according to claim 1, wherein, when evaluated in a wavelength range of 400 nm to 2500 nm, a transmittance deviation with respect to the total light average transmittance in the region is 10% or less.   The step of melting the glass raw material, the step of molding the melted glass, the step of gradually cooling the molded glass, and the shaped glass after the slow cooling are continued at a heating temperature of 730 to 850 ° C. for 8 to 30 hours. And a step of heating the substrate. A method for producing a light diffusing glass member, comprising:

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