JPH08217485A - Ultraviolet absorbing glass - Google Patents

Abstract

PURPOSE: To obtain ultraviolet absorbing glass having green-based color tone, capable of melting without reducing a batch-charging amount under operation conditions of oven similar to the case of ordinary color plate glass. CONSTITUTION: This glass is constituted of a base glass composition comprising 65-80wt.% SiO2 , 0-5wt.% Al2 O3 , 0-5wt.% B2 O3 , 0-10wt.% MgO, 5-15wt.% CaO, 10-18wt.% Na2 O, 0-5wt.% K2 O, 5-15wt.% MgO+CaO and 10-20wt.% Na2 O+K2 O, and 0.2-0.7wt.% (in terms of Fe2 O3 ) total iron oxide having 0.20-0.29 ratio of FeO/total iron oxide, 0.1-2.0wt.% TiO2 , 0.1-1.5wt.% CeO2 and 0.0002-0.01wt.% CoO as coloring components.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to ultraviolet absorbing glass. More specifically, it relates to an ultraviolet absorbing glass having a greenish color tone which is excellent in ultraviolet absorbing ability.

[0002]

2. Description of the Related Art In recent years, glass having a greenish color tone has been favored as glass for vehicles. Generally, green glass contains iron oxide as a main coloring component, and total iron oxide is converted to Fe ₂ O ₃
Convert the concentration in the (hereinafter, T-Fe ₂ O ₃ and displays) of about 0.5 wt% or more and Fe relative to T-Fe ₂ O ₃
It is known that a weight ratio of O of about 0.24 or more can be obtained.

Further, from the viewpoint of preventing the deterioration of interior materials due to the upsizing of interiors of automobiles in recent years, there has been proposed a glass having a greenish color tone imparted with an ultraviolet absorbing ability as a window glass for automobiles.

For example, the ultraviolet absorbing glass having a greenish color tone disclosed in Japanese Patent Laid-Open No. 3-187946 has a Si content of 65 to 75%, expressed as a percentage by weight, as a mother composition.
O _2, 0 to 3% of Al ₂ O _3, 1~5% of MgO, 5 to 1
5% of CaO, 10 to 15 percent of Na ₂ O, and 0-4%
In a glass containing K ₂ O of 0.51 to 0.51 as a coloring component.
0.96% and FeO / T-Fe ₂ O ₃ ratio of 0.23
Total iron oxide in terms of Fe ₂ O ₃ of ～0.29, 0.2
It contains 1.4% CeO ₂ and 0 to 0.85 TiO ₂ .

The ultraviolet absorbing glass having a greenish color tone disclosed in JP-A-6-56466 is a soda-containing glass.
The lime-silica base glass composition has a coloring component of 0.
In 53 to 0.70 percent, and total iron oxide FeO / T-Fe ₂ O ₃ ratio in terms of Fe ₂ O ₃ of 0.30 to 0.40,
0.5 to 0.8% of CeO _2, and 0.2 to 0.4 of the T
It contains iO ₂ .

Further, the ultraviolet absorbing glass having a greenish color tone disclosed in JP-A-6-191881 has a soda-lime-silica-based mother glass composition which exceeds 0.6% as a coloring component and FeO. / T-Fe ₂ O ₃ ratio of 0.3
It contains less than 5 total iron oxide converted to Fe ₂ O ₃ and less than 2.0% TiO ₂ .

Further, the above-mentioned respective prior arts disclose that they are useful as an infrared absorbing glass because they have a large absolute amount of FeO concentration having a high infrared (heat ray) absorbing ability.

Further, CeO ₂ , Ti as an ultraviolet absorber is used.
When O ₂ is added, the total iron content is increased in order to give the glass a greenish color tone, or FeO / TF
It is disclosed that the e ₂ O ₃ ratio must be made relatively large to increase the absolute amount of the FeO concentration having the absorbing ability on the long wavelength side in the visible region.

[0009]

However, when a glass batch containing a high concentration of FeO is melted, most of the heat of combustion due to the combustion of heavy oil is absorbed near the surface of the glass substrate due to its heat ray absorbing ability. I will end up. As a result, the temperature of the floor of the glass melting tank (laying temperature) decreases. In order to obtain a glass with few defects under such conditions, there are problems in glass production, such as a decrease in batch input amount or use of an electric booster during melting. Also,
Radiant heat from the surface of the glass substrate at high temperature raises the ceiling temperature (compressed temperature) of the melting tank, which shortens the life of the kiln.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to melt the glass under the same operating conditions of the kiln as in the case of the ordinary colored plate glass without reducing the batch input amount. An object of the present invention is to provide a UV-absorbing glass having a greenish color tone. For more details,
By combining titanium oxide, cerium oxide, which is an ultraviolet absorber, and cobalt oxide, which has a main absorption ability in the visible range, even if the total iron content and the FeO / T-Fe ₂ O ₃ ratio are kept relatively low, the expected It is intended to provide an ultraviolet absorbing glass exhibiting a greenish color tone.

[0011]

That is, the present invention, expressed in weight percent, is 65-80% SiO ₂ , 0-5% A.
l ₂ O ₃ , 0-5% B ₂ O ₃ , 0-10% MgO, 5-
15% CaO, 10-18% Na ₂ O, 0-5% K ₂ O, 5-15% MgO + CaO, and 10-20
% Of Na ₂ O + K ₂ O as a coloring component and Fe ₂ O ₃ of 0.2 to 0.7% and a FeO / total iron oxide ratio of 0.20 to 0.30. Converted total iron oxide, 0.1 to 2.0% TiO ₂ , 0 to 1.5% Ce
O _2, and consists of 0.0002 to 0.01% of CoO, and more preferably as the coloring components, from 0.3 to 0.
6% and FeO / total iron oxide ratio of 0.22-0.2
No. 8 total iron oxide converted to Fe ₂ O ₃ , 0.4 to 1.5% TiO ₂ , 0.1 to 1.0% CeO ₂ , and 0.000
It is an ultraviolet-absorbing glass characterized by comprising 2 to 0.008% CoO.

The ultraviolet absorbing glass of the present invention has a visible light transmittance of 68% or more measured by using the A light source of the glass converted to a thickness of 4 mm, and the dominant wavelength measured by using the C light source is 49%.
It preferably has optical characteristics of 5 to 540 nm, total solar energy transmittance of less than 60%, and ultraviolet transmittance of less than 38%.

The reasons for limiting the composition of the ultraviolet absorbing glass of the present invention will be described below. However, the following composition is% by weight
It is what was displayed in.

SiO ₂ is the main component forming the skeleton of glass. If the SiO ₂ content is less than 65%, the durability of the glass will decrease, and if it exceeds 80%, it will be difficult to melt the glass.

Al ₂ O ₃ is a component that improves the durability of glass, but if it exceeds 5%, melting of glass becomes difficult. It is preferably in the range of 0.1 to 2%.

B ₂ O ₃ is used for improving the durability of the glass and as a melting aid, but may not be contained in the glass. If B ₂ O ₃ exceeds 5%, inconvenience at the time of molding due to volatilization of B ₂ O _{3 or} the like occurs, so the upper limit is 5%.

MgO and CaO are used to improve the durability of glass and to adjust the devitrification temperature and viscosity during molding. When MgO exceeds 10%, the devitrification temperature rises. When CaO is less than 5% or exceeds 15%, the devitrification temperature rises. If the total amount of MgO and CaO is less than 5%, the durability of the glass will decrease, and if it exceeds 15%, the devitrification temperature will increase.

Na ₂ O and K ₂ O are used as glass melting accelerators. When the content of Na ₂ O is less than 10% or the total content of Na ₂ O and K ₂ O is less than 10%, the dissolution promoting effect is poor, and Na ₂ O exceeds 18%, or Na ₂ O and K ₂ O
If the total amount of O exceeds 20%, the durability of glass decreases. K ₂ O is 5% because the raw material is more expensive than Na ₂ O
It is not preferable to exceed.

Iron oxide in glass exists in the state of Fe ₂ O ₃ and FeO. 0.2% of total iron oxide converted to Fe ₂ O ₃
If it is less than the above range, the effect of absorbing ultraviolet rays is small and desired ultraviolet ray absorbing ability cannot be obtained. On the other hand, if it exceeds 0.7%, the batch input amount must be reduced as described above, and an electric booster must be used at the time of melting to prevent it, which causes problems in glass manufacturing. It is not preferable.

In order to obtain a desired greenish color tone and a desired total solar energy absorption capacity with such a glass having a relatively low total iron content, the ratio of FeO / T-Fe ₂ O ₃ should be set. It is important that the lower limit is 0.20 or more, more preferably 0.22 or more, and the upper limit is 0.29 or less, more preferably 0.28 or less. However, if this ratio exceeds 0.29, the absolute amount of FeO increases too much during glass melting, which causes an increase in the temperature of the melting furnace and a decrease in the laying temperature, which is not preferable.

TiO ₂ is used as an ultraviolet absorbing component. If TiO ₂ is less than 0.1%, a sufficient ultraviolet absorbing effect cannot be obtained, and if it exceeds 2.0%, the absorption of visible light on the short wavelength side becomes too large, and the glass becomes yellowish.
The desired visible light transmittance and main wavelength cannot be obtained. In addition,
A more preferable range is 0.4 to 1.5%.

CoO is an essential component for obtaining a greenish color tone. Conventionally, it has been considered that when a large amount of TiO ₂ is added to a glass having a small amount of Fe ₂ O ₃ , the color of the glass changes from usable green to unusable yellow green or yellow. However, in the present invention, it was found that by adding CoO, the desired greenish color tone can be obtained even when TiO ₂ coexists. But Co
If the O concentration is less than 2 ppm, it is insufficient to obtain a green color tone, while if it exceeds 100 ppm, not only the glass changes from a green color tone to a blue color tone, but also the visible light absorption capacity becomes too large. It is not preferable because the desired visible light transmittance cannot be secured. The more preferable range is 2 to 80 ppm.

CeO ₂ is a component that enhances the ability to absorb ultraviolet rays. However, when CeO ₂ is less than 0.1% or exceeds 1.5%, not only the glass starts to have a yellowish color tone, but also the cost at the time of glass production increases, which is not preferable. The more preferable range is 0.1 to 1.0%.

[0024]

The UV absorbing glass according to the present invention has a greenish color tone and exhibits a high UV absorbing ability and a high visible light transmittance.

[0025]

EXAMPLES Specific examples of the present invention will be described below.

(Example) A typical soda lime silica glass batch component was appropriately mixed with ferric oxide, titanium oxide, cerium oxide, cobalt oxide and a carbon-based reducing agent, and this raw material was heated in an electric furnace at 1500 ° C. It was heated and melted. After melting for 4 hours, pour the glass substrate onto a stainless steel plate,
The glass was gradually cooled to room temperature to obtain glass having a thickness of about 6 mm. Next, this glass was polished to a thickness of 4 mm to obtain a sample of this example.

Table 1 shows the total iron oxide concentration, the FeO / T-Fe ₂ O ₃ ratio, the TiO ₂ concentration, the CeO ₂ concentration, the CoO concentration, and their optical characteristic values of the obtained sample.
Each characteristic value of the obtained sample is shown.

As is apparent from Table 1, the sample of this example has a visible light transmittance of 68% or more measured by using the A light source, and a dominant wavelength measured by using the C light source of 495 to 540n.
m, the total solar energy transmittance is less than 60%, and the ultraviolet transmittance is less than 38%.

[0029]

[Table 1]

Comparative Example Table 1 shows a comparative example for the present invention. In Comparative Example 1, the total iron oxide concentration is less than the concentration range proposed in the present invention. As a result, the visible light transmittance with the A light source is within the range of the present invention, but the dominant wavelength with the C light source is less than the range of the present invention, and the total solar energy transmittance and the ultraviolet transmittance are within the range of the present invention. Out of range.
Comparative Example 2 shows an example in which the FeO / T-Fe ₂ O ₃ ratio was melted under the condition smaller than the range proposed in the present invention, and the visible light transmittance and the ultraviolet light transmittance at the A light source were Although within the scope of the invention, the dominant wavelength and total solar energy transmission at the C light source are beyond the scope of the invention.

[0031]

As described above in detail, according to the UV absorbing glass of the present invention, the total iron oxide content, since FeO / T-Fe ₂ O ₃ ratio are both relatively small, at operating conditions of normal float furnace It can be melted. Therefore, it is possible to obtain a glass having a greenish color tone and having a high ultraviolet absorptivity and a high visible light transmittance without reducing the batch input amount.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C03C 3/091 C03C 3/091

Claims (5)

[Claims] 1. 65-80% Si, expressed as wt%
O ₂ , 0-5% Al ₂ O ₃ , 0-5% B ₂ O ₃ , 0-1
0% MgO, 5-15% CaO, 10-18% N
a ₂ O, 0-5% K ₂ O, 5-15% MgO + Ca
O, and a basic glass composition consisting of 10 to 20% Na ₂ O + K ₂ O, and 0.2 to 0.7% as a coloring component, and a FeO / total iron oxide ratio of 0.20 to 0.29. Fe ₂
Total iron oxide converted to O ₃ , 0.1 to 2.0% TiO ₂ ,
0.1 to 1.5% of CeO _2, and from 0.0002 to 0.
An ultraviolet-absorbing glass comprising 01% CoO. 2. The coloring component is 0.3 to 0.6%
And FeO / total iron oxide ratio converted to Fe ₂ O ₃ of 0.22 to 0.28, total iron oxide of 0.4 to 1.5% Ti.
O ₂ , 0.1-1.0% CeO ₂ , and 0.0002-
The ultraviolet absorbing glass according to claim 1, which comprises 0.008% CoO. 3. The ultraviolet absorbing glass according to claim 1, which has a visible light transmittance of 68% or more as measured using a light source A of the glass converted into a thickness of 4 mm. 4. The ultraviolet absorbing glass according to claim 1, which has a dominant wavelength of 490 to 540 nm measured by using a glass C light source converted into a thickness of 4 mm. 5. The ultraviolet absorbing glass according to claim 1, wherein the ultraviolet transmittance of the glass converted to a thickness of 4 mm is less than 38%.