JP2567449B2 - Yellow core thermometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass part of a thermometer, and more particularly to improvement of the composition of yellow glass used for the yellow core of a thermometer.

[Conventional technology]

Conventionally, thermometers have been variously devised to improve the visibility of fine mercury threads and make them easier to see. For example,
Known methods include molding a glass capillary into a convex lens shape to enlarge the mercury thread, and optically coloring the mercury thread in blue to emphasize the contrast with the scale plate. Also,
In addition to these methods, there is a method in which a yellow glass layer is provided on the back side of a capillary tube in which mercury is sealed so as to make the contrast with a mercury thread appearing gray to black clear. A yellow core thermometer is shown in FIGS. 1 to 3 as an example of such a thermometer. 1 and 2 show a flat tube (1) which is an outer tube, and a yellow core (2) and a scale plate (3) inside the flat tube (1). FIG. 3 shows a yellow core glass layer having a triangular cross section. (4) and the diameter that occupies a part of it 30
Shown is a mercury encapsulation capillary (5) of ~ 40 μm, a yellow glass layer (6) along the back side of the capillary. Conventionally, the glass of this yellow glass layer has been made of soda-lime glass as the basic glass and CdB and Se added as coloring components.

[Problems to be Solved by the Invention]

It is desirable that such a yellow glass layer has a thickness of about 0.1 mm and exhibits a sufficiently saturated yellow color, and that this coloring is not influenced by the atmosphere or temperature.
However, since CdB easily volatilizes in conventional yellow glass,
There was a drawback that the stability of the color tone was poor due to the temperature change during melting and molding, and that wood-grain-like color unevenness in which yellow portions and milky white portions alternately appeared was likely to occur. Further, even if the color is uniformly developed, the glass itself has a strong light-transmitting property, and the thermometer using this glass has an insufficient contrast with the mercury thread and is not easy to read. Further, in this yellow glass, it is necessary to consider the coefficient of thermal expansion, the transition point, and the softening temperature so as to minimize the residual strain during welding with the glass for thermometer material. ENA 16 III (average linear expansion coefficient of 80-
86 × 10 ^-7 / ° C) is the most commonly used.

The present invention has been made in consideration of the above circumstances.
An object of the present invention is to provide a yellow core thermometer having a yellow glass layer having a coefficient of thermal expansion similar to that of III and maintaining sufficient saturation and having a stable color tone.

[Means and Actions for Solving Problems]

In order to achieve the above-mentioned object, the present invention uses yellow glass in which the content ratio of CdS and Se is limited to adjust the saturation and F is added to stabilize the color tone. That is, in the present invention, the weight percentage is SiO ₂ 60 to 70%, Al ₂ O ₃ 3
_{~10%, Na 2 O7~18%,} K 2 O1~5%, CaO1~8%, MgO0~1
%, ZnO 1-8%, B ₂ O ₃ 1-5%, CdS 0.1-2%, Se 0-1%
(Not including 0), F0.1 to 3%, the CdS / Se weight ratio is in the range of 10 to 100, and the average linear expansion coefficient is 80 to 96 × 10 ^−7. A yellow core thermometer comprising a yellow core formed by arranging a yellow glass layer having a temperature of / ° C.

The reason for limiting the composition range will be described below.

SiO ₂ is the main component that forms the network of glass, but 60%
If it is less than 70%, the thermal expansion coefficient becomes too large, and if it exceeds 70%, the meltability of the glass deteriorates. Al ₂ O ₃ has the effect of improving the chemical durability of the glass, but if it is less than 3%, it has no effect, and if it exceeds 10%, the meltability deteriorates. Na ₂ O is 7%
If it is less than the above range, the coefficient of thermal expansion becomes smaller than the above range, and if it exceeds 18%, the coefficient of thermal expansion becomes larger than the above range. K ₂ O
Has the effect of improving the meltability of glass, but if it is less than 14%, it has no effect, and if it exceeds 5%, the coefficient of thermal expansion becomes too large. ZnO suppresses the volatilization loss of Cds and stabilizes the color tone, but if it is less than 1%, it has no effect, and if it exceeds 8%, the chemical durability deteriorates. CaO, MgO, and B ₂ O ₃ have the effect of improving chemical durability and improving the meltability, but if the content is less than the above lower limit, the meltability of the glass deteriorates, and if it exceeds the above upper limit, the chemical resistance increases. Durability deteriorates. CdS is an essential component that is added as a colorant and has a yellow color.
If it is less than 1%, the glass becomes bluish green, and the desired color cannot be obtained. Even if it is added in excess of 2%, it does not remain in the glass due to volatilization. The addition of Se adds redness to the color tone, and makes the saturation of yellow due to CdS stand out more vividly, but if it exceeds 1%, the red color becomes strong and the desired coloration cannot be obtained. F acts as an emulsifying agent and has the effect of reducing the transmittance of the glass and stabilizing the color tone, but if it is less than 0.1%, it has no effect and color unevenness occurs in the glass, and if added in excess of 3%. Also does not remain in the glass due to volatilization. In addition, the ratio of CdS and Se is an important factor in determining the color tone of glass, and CdS / Se
If the weight ratio of Se is less than 10, the red color becomes too strong, and if it exceeds 100, the above effect due to the addition of Se cannot be obtained.

Further, the thermometer provided with the colored layer made of the yellow glass behind the capillary tube enclosing mercury has a high contrast with the mercury thread due to the yellow glass layer having a uniform color tone and sufficient saturation. It is easy to detect the height position.

〔Example〕

Next, examples of the present invention will be described. In the table, No. 1 ~
The glass of No. 4 is an example of the present invention, and the glass of No. 5 is a conventional example. The glass composition in the table is shown by weight percentage.

Raw materials were prepared so as to have the glass composition shown in the above table, melted in a crucible at a temperature of 1350 to 1400 ° C. for 2 hours, cast in a mold and gradually cooled to obtain a sample. This was polished on a glass plate having a thickness of 0.5 mm and the transmittance at a wavelength of 700 nm was measured. With emulsified glass, long-wavelength light is less affected by scattering than short-wavelength light, and is easily transmitted. Therefore, it can be said that the glass having a lower transmittance at a wavelength of 700 nm has a higher opacity.

If the transmittance exceeds 80%, the glass becomes more transparent as a criterion for judging the milkiness, and when molded into a thermometer, the back surface of the yellow glass layer is transparent and the contrast with the mercury thread becomes insufficient. , It becomes difficult to check the height of the mercury thread.

In the conventional cold No. 5 glass, the yellow part and the milky white part appear as wood-like color unevenness, and the overall color tone is thin and the transmittance is high. On the other hand, the glass of the example according to the present invention,
In each case, the transmittance at 700 nm was 80% or less, there was no color unevenness, and a bright yellow color was exhibited. Further, since it has a thermal expansion coefficient similar to that of Ena 16 III glass, the residual strain is small even when it is fused with Ena 16 III.

Therefore, the thermometer created using the yellow glass according to the present invention, the glass welded portion is stable against temperature changes, and the contrast between the yellow glass layer and the mercury thread becomes clear,
It is easy to detect the height position of the mercury thread.

〔The invention's effect〕

As described above, the yellow core thermometer of the present invention has a yellow core having a coefficient of thermal expansion similar to that of Ena 16 III and having a yellow glass layer having a sufficient saturation and a stable color tone. The moldability is good, the height position of the mercury thread is easy to confirm, and the temperature can be easily measured.

[Brief description of drawings]

FIG. 1 is a side view of the yellow core thermometer, FIG. 2 is a sectional view showing a part of FIG. 1, and FIG. 3 is a sectional view of the yellow core.

Claims (1)

(57) [Claims] 1. A weight percentage of SiO ₂ 60 to 70%, Al ₂ O ₃ 3 to 10
%, Na ₂ O 7-18%, K ₂ O 1-5%, CaO 1-8%, MgO 0-1%, Zn
_{O1~8%, B 2 O 3 1~5} %, CdS0.1~2%, ( not including but 0) Se0~1%, has a composition consisting F0.1~3%, CdS / S
A yellow core comprising a yellow glass layer having a weight ratio of e within the range of 10 to 100 and having an average linear expansion coefficient of 80 to 96 × 10 ⁻⁷ / ° C. thermometer.