JPH0211535B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an infrared transmitting glass. The infrared transmitting glass of the present invention is useful for applications such as glass fibers for optical communications and infrared transmitting lenses. BACKGROUND ART Glass fibers made of oxide glass, such as quartz glass, which is well known as a light-transmitting material, and general optical glass, are already in practical use. However, such glass fibers have a drawback in that they can only be used mainly for light in the visible to near-infrared range. That is, these glasses have inherent absorption in the wavelength range of 3 μm or more, and cannot transmit light in the longer wavelength infrared region. Fluoride glass, chalcogenide glass, etc. are known as glass materials that transmit light with a wavelength longer than 3 μm, but the transmission wavelength of these is also 8 to 8 μm.
The limit is about 9 μm. Recently, lasers as light sources in the infrared region have been developed, such as a carbon dioxide laser with an oscillation wavelength of 10.6 μm. Materials that transmit light in this wavelength range include KBr, TlBr, and TlI.
Crystalline materials such as However, since such crystalline materials have poor workability, it is not easy to manufacture products with arbitrary shapes. Therefore, in order to take advantage of the characteristics of glass that have fewer restrictions on size and shape, there is a strong desire for the emergence of a new glass material that can transmit long wavelength infrared rays. As such a glass material, the present inventors have
_{A ZnBr 2 -TlBr} -PbBr ₂ glass containing ZnBr 2 as the main component was completed (Japanese Patent Application No. 59-93508). This glass can transmit light up to a wavelength of 25 μm, and has excellent properties as an infrared transmitting glass.
The drawback is that the glass transition temperature is 40 to 50°C, which is relatively close to room temperature. That is, glass exhibits viscoelastic behavior at temperatures above its transition temperature and is deformed by external forces. Therefore, the above with a transition temperature close to room temperature
ZnBr ₂ -TlBr-PbBr ₂ glass can only be used in applications with limited usage conditions. Problems to be Solved by the Invention Therefore, the main object of the present invention is to provide a glass of a new composition that transmits infrared rays, has a high glass transition temperature, and has fewer restrictions on usage conditions. Means for Solving the Problems As a result of repeated research in view of the problems of the prior art as described above, the present inventor has discovered that the present invention has a specific composition.
It was discovered that ZnBr ₂ -MBr (where M is an alkali metal) -CaBr ₂ -based glass and ZnBr ₂ -MBr-BaBr _2- based glass exhibit desired excellent performance as infrared transmitting glass, and in order to complete the present invention. It was it. That is, the present invention provides the following two types of glasses. ZnBr ₂ , MBr (M is an alkali metal) and
CaBr ₂ is an essential component, and its composition ratio is the first
In the molar ratio triangular component diagram shown in the figure, A(65,
35,0), B(60,20,20), C(50,
25, 25), D (40, 35, 25), E (4
0,55,5) and F(45,55,0). ZnBr ₂ , MBr (M is an alkali metal) and BaBr
is an essential component, and its composition ratio is G(65, 35,
0), H(65,20,15), I(55,20,
25), J (45, 30, 25) and K (45,
An infrared transmitting glass characterized by being located within an area surrounded by straight lines connecting each point of 55,0). The glass of the present invention is colorless and transparent, can transmit infrared rays of 25 μm or less, and has a glass transition temperature of about 80 to 90°C. Therefore, the restriction due to temperature during use is limited to the above-mentioned ZnBr ₂ −TlBr−
It is extremely small compared to PbBr ₂ glass and can be used in a wide range of applications as an infrared transmitting glass. The raw materials for producing the glass of the present invention are ZnBr ₂ , MBr (M
is an alkali metal such as K, Na, Li) and CaBr ₂
(or BaBr ₂ ). These raw materials are hydrates,
If impurities such as oxides are contained, it may cause a decrease in the infrared transmittance of the resulting glass and may also reduce glass forming ability, so it is desirable to use raw materials with as few impurities as possible. The glass of the present invention can be produced by a common glass melting operation. That is, first, the raw materials are weighed, mixed, and then heated and melted in a crucible made of platinum, gold, or the like. The melting temperature is usually about 350 to 500°C, more preferably about 450°C. If the melting temperature is less than 350℃, the raw material may not melt.
On the other hand, if the temperature exceeds 500℃, there is a risk that some components will evaporate. The melting time can vary widely depending on the amount of raw materials, heating capacity, etc., but normally a sufficiently uniform glass is formed in about 30 minutes, so there is no need to continue melting for an unnecessarily long period of time. In order to promote homogenization of the glass during melting, stirring is preferably performed. Furthermore, in order to obtain a glass with high infrared transmittance, it is particularly desirable to adjust the atmosphere during melting. i.e. water from the atmosphere into the molten glass;
The incorporation of oxygen and the like causes the formation of hydroxides, oxides, etc. in the glass, and these products have a large effect on the infrared transmittance of the glass. Therefore, it is particularly preferable that the melting be carried out in an inert gas atmosphere such as N ₂ or Ar. Alternatively, the generation of hydroxides, oxides, etc. can also be prevented by spraying bromine gas onto the surface of the melt. Next, pour the molten material into a mold made of metal or the like,
By cooling, a colorless and transparent glass is obtained. The glass thus obtained is formed into an optical fiber for optical communication, laser energy transmission, etc., or into a lens shape, according to a conventional method. Effects of the Invention The infrared transmitting glass of the present invention can transmit infrared rays up to 25 μm, and can be processed into any shape. Furthermore, the glass transition temperature is 80
It has excellent thermal stability as it can reach ~90℃. Therefore, it can be used for various purposes as a material that transmits infrared rays in the wavelength range of up to 25 μm, and is useful, for example, as an optical communication fiber or energy transmission fiber that transmits infrared rays. Furthermore, by molding it into a lens shape, it can also be used as an infrared transmitting lens. Examples Examples and comparative examples are shown below to further clarify the characteristics of the present invention. Example 1 16.98g of ZnBr, 6.27g of KBr, and 6.72g _{of BaBr2} were weighed, mixed, and heated at 460℃ for 30 minutes using a platinum crucible.
After melting for a minute, pour it out onto a metal plate, about 30×
A plate glass of 30×5 mm ³ was obtained. The operations up to this point were performed in a glove box purged with nitrogen gas. The composition of the obtained glass was 50 mol% _ZnBr2 ,
KBr was 35 mol % and BaBr ₂ was 15 mol %, the glass transition temperature was 91°C, and the crystallization temperature was 156°C. Examples 2 and 3 Infrared transmitting glasses were obtained in the same manner as in Example 1, except that the blending ratio of the raw materials was changed. Table 1 shows the composition of the glass, as well as its transition temperature (Tg) and crystallization temperature (Tc). In addition, Table 1 shows Example 1, Examples 4 and 5 described below.
The composition, Tg, and Tc of the glass of Comparative Example 1 are also shown. Example 4 After weighing and mixing 18.75 g of ZnBr ₂ , 7.92 g of KBr and 3.38 g of CaBr ₂ , a sheet glass was obtained in the same manner as in Example 1. Example 5 13.2 g of ZnBr ₂ , 13.3 g of TlBr and 3.5 g of BaBr ₂ were weighed, mixed, melted at 430°C for 30 minutes using a platinum crucible, and then poured onto a metal plate to form an approximately 30×30
A 5 mm x 5 mm plate glass was obtained. The operations up to this point were performed in a glove box purged with nitrogen gas. The composition of the obtained glass was 50 mol% _ZnBr2 ,
It contained 40 mol% of TlBr and 10 mol% of BaBr ₂ , the glass transition temperature was 60°C, and the crystallization temperature was 122°C. Comparative Example 1 42.8 g of ZnBr ₂ , 14.0 g of PbBr ₂ and 43.2 g of TlBr were weighed and mixed, melted at 420°C for 30 minutes using a platinum crucible, and poured onto a metal plate to form a 70×70×5 (mm
³ ) A plate glass of about 100% was obtained. Note that the operations up to this point were performed under a nitrogen gas atmosphere. The resulting glass contains 50 mol% ZnBr ₂ , 10 mol% PbBr ₂ and TlBr40
It was a colorless and transparent glass of mol%.

[Table] From the results shown in Table 1, it is clear that the glass of the present invention has excellent thermal stability. The infrared transmittance of each glass obtained in Examples 2 to 5 was also almost the same as that of the glass obtained in Example 1 shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a triangular molar ratio diagram showing the composition range constituting the invention as claimed in claim 1. Second
The figure is a triangular molar ratio diagram showing the composition range constituting the invention as claimed in claim 2. FIG. 3 is a graph showing the transmittance curve of the infrared transmitting glass of the present invention obtained in Example 1.

Claims (1)

[Claims] 1 ZnBr ₂ , MBr (M is an alkali metal) and
CaBr ₂ is an essential component, and its composition ratio is A(65,3
5,0), B(60,20,20), C(50,2
5,25), D(40,35,25), E(40,5
5,5) and F(45,55,0). 2 ZnBr ₂ , MBr (M is an alkali metal) and
BaBr ₂ is an essential component, and its composition ratio is G(65,3
5,0), H(65,20,15), I(55,2
0,25), J(45,30,25) and K(45,
An infrared transmitting glass characterized by being located within an area surrounded by straight lines connecting each point of 55,0).