JPH0643254B2 - Fluorophosphate glass - Google Patents

Description

The present invention relates to a fluorophosphate glass, for example, a color VTR.
The present invention relates to a filter glass suitable for color correction of a camera.

[Prior Art] Since the spectral sensitivity of light from an image pickup tube generally used in a color VTR camera extends from the visible region to the near infrared region of 950 nm, this near infrared region is cut by a filter,
Unless the spectral sensitivity is approximated to the human visual sensitivity, the image becomes reddish and good color reproduction cannot be obtained.
On the other hand, if the ultraviolet absorption of the filter reaches the visible range, the image will be darkened this time. Therefore, this type of filter is required to have a property of transmitting light of 400 to 520 nm as high as possible and absorbing light of 550 to 950 nm as much as possible. Conventionally, as this kind of near infrared absorption filter, a glass obtained by adding CuO to phosphate glass has been used.

[Problems to be Solved by the Invention]

However, since phosphate glass originally has poor weather resistance, in order to improve it until it can be used practically, a relatively large amount of Al ₂ O is disclosed, for example, as disclosed in JP-A-62-128943. Requires the addition of ₃ . As a result, the melting temperature rises, and the higher the temperature, the more easily copper ions tend to be reduced, so the divalent ion Cu ^{2+ of the} glass component copper having absorption in the near infrared region is reduced,
There was a tendency of characteristic deterioration that the monovalent Cu ⁺ ion having absorption in the ultraviolet region was changed to lower the transmittance in the visible region and increase the transmittance in the infrared region. On the other hand, if an attempt is made to improve the transmittance characteristic, the melting temperature will be lowered by addition of an alkali or the like so that the divalent ion Cu ²⁺ of copper in the glass component is reduced and the monovalent Cu ⁺ ion is not left. ,
At the same time, this further deteriorates the weather resistance of the glass itself. Therefore, when manufacturing a near-infrared absorption filter of this kind using a phosphate glass, the fact is that it has been practically provided by finding a compromise between the transmittance characteristic and the weather resistance, which are in a contradictory relationship.

Therefore, the present invention has been made in view of the above-described conventional problems, and an object thereof is to sufficiently satisfy the transmittance characteristics as a near infrared absorption filter required for a filter for a color VTR camera, and to put it into practical use. It is intended to provide a fluorophosphate glass having extremely excellent weather resistance capable of sufficiently withstanding.

[Means for Solving the Problems]

The fluorophosphate glass of the present invention is based on P ₂ O ₅ as a component forming a glass skeleton, AF ₃ and RF ₂ (atoms) that maintain sufficient devitrification resistance for mass production and improve weather resistance. Divalent metals Ba, Sr, Ca, Mg,
R′F (monovalent metal Li, Na having a valence of 1) for lowering the viscosity of the glass in the melting temperature range and lowering its melting point based on a glass containing as an essential component the total amount of fluorides of Zn and Pb). , K
R'Fm (metals with a valence of 3 to 5 La, Y, Gd, Si, B, Zr, Ta) that improve wear resistance without affecting the total amount of fluoride and the transmittance characteristics. (A total amount of fluoride) is added to a fluorophosphate glass to which CuO is added as an essential component for absorption in the near infrared region.
The high weather resistance and the transmittance characteristics of the fluorophosphate glass of the present invention do not change significantly even if the type and content of the divalent component in the fluorophosphate glass are changed, and the divalent component has one The same applies when a part is replaced with a monovalent component or a high valence component, or a part of the fluoride is replaced with an oxide, and when up to 70% by weight of the total amount of fluoride is replaced with an oxide. It can maintain the desired properties.

That is, in the fluorophosphate glass of the present invention, the basic glass is P ₂ O ₅ 5 to 45%, AlF _{3 1 to} 35%, and RF by weight%.
₂ (metals with divalent valences Ba, Sr, Ca, Mg, Z
n, Pb fluoride total amount) 10-75%, R'F (monovalent valence metal Li, Na, K fluoride total amount) 0-4
0%, R ″ Fm (metal having a valence of 3 to 5 La, Y, G
d, Si, B, Zr, Ta fluoride total amount) 0 to 15%, and 0.2 to 15% by weight of CuO is added to 100 parts by weight of the basic glass. Have.

INDUSTRIAL APPLICABILITY The fluorophosphate glass of the present invention has a spectral transmittance characteristic of selectively absorbing wavelengths longer than 500 nm, and is preferably used as a color correction filter glass.

In the fluorophosphate glass of the present invention, P ₂ O ₅ is a component forming a glass skeleton, and if it is less than 5 wt%, vitrification becomes difficult, and if it exceeds 45 wt%, the weather resistance is deteriorated. Therefore, the P ₂ O ₅ content is in the range of ₅ to 45 wt%, but is preferably in the range of 10 to 40 wt%.
Further, AF ₃ is an effective component for improving the weather resistance, and if it is less than 1 wt%, that effect cannot be obtained, and if it exceeds 35 wt%, the meltability of glass is lowered. Therefore AF
₃ was in the range of 1 to 35 wt%, but preferably 1 to 30
The range is wt%. In addition, the divalent component RF ₂ (having a valence of 2
The valent metals Ba, Sr, Ca, Mg, Zn, and Pb (the total amount of fluorides) are effective components for not lowering the weather resistance, and if BaF ₂ exceeds 40 wt%, devitrification is likely to occur. , 0 to 4 wt% is preferable. If SrF ₂ exceeds 40 wt%, devitrification is likely to occur, so 0-40
A wt% range is preferred. If CaF ₂ exceeds 30 wt%, devitrification tends to occur, so the range of 0 to 30 wt% is preferable. If MgF ₂ exceeds 20 wt%, devitrification tends to occur, so the range of 0 to 20 wt% is preferable. If ZnF ₂ exceeds 30 wt%, devitrification tends to occur, so the range of 0 to 30 wt% is preferable. In addition, PbF ₂
If it exceeds 30 wt%, devitrification tends to occur, so 0-3
The range of 0 wt% is preferred. Further, when the total amount of the divalent component RF ₂ is less than 10 wt%, it is difficult to vitrify, and 7
If it exceeds 5 wt%, devitrification tends to occur. Therefore, the total amount of the bivalent component RF ₂ is set in the range of 10 to 75 wt%,
It is preferably in the range of 14 to 60 wt%. Monovalent component R '
F is a component that lowers the melting temperature and viscosity of glass, but if LiF exceeds 20 wt%, the weather resistance is lowered, so the range of 0-20 wt% is preferable, and NaF is 1
If it exceeds 0 wt%, the weather resistance will decrease, so 0-10
The range of wt% is preferable, and if KF exceeds 10 wt%, the weather resistance is deteriorated, so the range of 0 to 10 wt% is preferable. Furthermore, if the total amount of the monovalent component R'F exceeds 40% by weight, the weather resistance is deteriorated. Therefore, the monovalent component R '
The total amount of F is in the range of 0 to 40 wt%, preferably 0 to 25 wt%. When a high valence component R ″ Fm is added as another fluoride, the abrasion resistance can be improved without adversely affecting the transmittance characteristics. The amount is 15wt%
If it exceeds, the glass tends to be unstable, so that the total amount of the high valence component R ″ Fm is 0 to 15 wt%.
The range of 0 to 8 wt% of LaF ₃ and YF ₃ in the high valence component is preferable for stability of the glass. Further, of the above-mentioned components, it is possible to replace up to 70 wt% of the total amount of fluoride with an oxide, but if it exceeds that, the desired excellent weather resistance and transmittance characteristics cannot be obtained, The substitution of fluoride for oxide is preferably 50 wt% based on the total weight of fluoride.
Up to%. CuO is an essential component for absorption in the near infrared region. If it is less than 0.2 wt%, its absorption will be insufficient, and if it exceeds 15 wt%, the glass will be unstable. Therefore, the content of CuO is set in the range of 0.2 to 15 wt%, preferably 0.2 to 13 wt%.

In the glass technical field, it is often the case that the components constituting the glass are represented by weight% as described above, and the cation component is represented by Cationic% and the anion component is represented by Anionic%. Based on the fluorophosphate glass compositions of Composition Nos. 1 to 10 of the examples described in 1., the preferable composition range of the cation component is expressed by Cationic%, P ⁵⁺ is 11 to 43%, A ³⁺
Is 1 to 29%, R ion (divalent metal Ba, S
The total amount of r, Ca, Mg, Zn, and Pb ions) is 14 to 5
0%, R'ion (monovalent metal Li, Na, K
0 to 43% of the total amount of ions, R ″ ion (having a valence of 3)
˜5 valent metal La, Y, Gd, Si, B, Zr, Ta ions) 0-8%, and Cu ²⁺ is 0.5-13.
%. In particular, it preferably contains at least one of R ′ ion and / or R ″ ion.
When the composition range of the preferable anion component is expressed in anionic%, F ⁻ is 17 to 80%.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to tables and drawings.

Table 1 below shows the glass compositions of the examples of the present invention and the comparative example as the prior art, and the time until the surface deterioration starts in the weather resistance test. The weather resistance test here means that the polished glass is kept under constant temperature and constant humidity conditions of about 65 ° C. and 90% relative humidity, and the surface condition is observed at regular intervals to confirm that the glass surface is not deteriorated. It shows the time until it is taken.

As described above, it is possible for glass researchers to divide the components that make up the glass into cation components and anion components, and to display these amounts in terms of Cationic and Anionic percentages. Since it is widely adopted for the sake of comparison of abundance, etc., Table 1 shows the composition of each fluorophosphate glass together with the weight% indication and the cationic and anionic percentage indications. Table 2 shows an example of conversion from wt% to Cationic% and Anionic% based on Example 1. Note that the A ³⁺ As is clear from Table 2, ^{A 3+} (26 derived from AF _3.
8%) and A ³⁺ (1.5%) derived from A ₂ O ₃ , but the total amount (28.3%) of these is AF ₃
It is described in the A ³⁺ column which is also written. Regarding the other cations, when fluoride and oxide are present, the total amount of the cation is described in the cation column in which "fluoride" is also described.

In Table 1 above, compositions Nos. 1 to 10 are examples according to the present invention,
Composition Nos. 11 and 12 are comparative examples according to JP-A-62-128943. First, a specific description will be given based on the composition No. 5 of the example. 27.8% by weight of P ₂ O ₅ ;
AF ₃ 10.2%, MgF ₂ 5.3%, CaF ₂ 1
0.4%, SrF ₂ 19.4%, BaF ₂ 15.0%,
_{Al 2 O 3 7.9%, Li} 2 O4.0% of basic glass 1
CuO is added so as to be 1.4% based on 100 parts by weight. As raw materials, orthophosphoric acid aqueous solution, aluminum hydroxide, aluminum fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, lithium carbonate, cupric oxide are mixed in a predetermined amount, and the lid is covered with a platinum crucible. After melting at 800 to 900 ° C., stirring to defoam and homogenize, the mixture was cast into a preheated mold and gradually cooled to obtain a glass filter. It should be noted that the use of a composite salt of aluminum phosphate, barium phosphate or the like as a raw material is not hindered.

The glass thus obtained was polished to obtain the above-mentioned 65.
It took about 1080 hours until the glass surface was altered at 90 ° C. and 90% relative humidity. Composition No. 1 of this example including glass of composition No. 5 of this example
All the glasses of Nos. 10 to 10 had weather resistance enough to clear about 950 hours under these conditions. On the other hand, regarding the glasses of composition Nos. 11 and 12 of the comparative example, 220 to 2
The surface began to deteriorate after about 40 hours, and after about 1000 hours, the surface became completely white, and the transparency of the glass was lost. From the above, it was found that the glass according to this example has extremely high weather resistance.

Next, the spectral transmittance curves of the above-mentioned examples and comparative examples are shown in the figure. In the figure, the glass of composition Nos. 2, 5, and 7 of the example and the glass of composition Nos. 11 and 12 of the comparative example are shown, but the thickness of the glass is 1.6 mm. As is clear from the figure, the glass according to this example has a wavelength of 360 to 500 as compared with the glass of the phosphate-based comparative example containing no fluoride.
It has excellent spectral transmittance characteristics as a filter for a color VTR camera, which has a high transmittance in nm and a lower wavelength side than that.

From the results of composition Nos. 1 to 10 in the above examples, P ⁵⁺ 11 to 43%, A ³⁺ 1 to 29%, R in Cationic%
Ion (divalent metal ion) 14 to 50%, R ion (1
(Valent metal ion) 0 to 43%, R ion (3 to 5 valent metal ion) 0 to 8%, and Cu ²⁺ 0.5 to 13%, and anionic% F ⁻ of 17 to 80%. With such a composition, the effect is further enhanced.

〔The invention's effect〕

As described above, the fluorophosphate glass of the present invention has an extremely excellent weather resistance which could not be produced conventionally, and at the same time has an extremely excellent effect that an ideal filter glass having further improved spectral transmittance characteristics can be produced. was gotten.

[Brief description of drawings]

The figure is a characteristic diagram showing the difference in the spectral transmittance between the fluorophosphate glass according to the embodiment of the present invention and the conventional glass.

Claims (3)

[Claims] 1. A base glass containing P ₂ O ₅ 5 to 45% by weight.
%, AlF _{3 1 to} 35%, RF ₂ (total amount of fluoride of divalent metal Ba, Sr, Ca, Mg, Zn, Pb)
10 to 75%, R'F (monovalent metal Li, N
0 to 40% of the total amount of fluorides of a and K, R ″ Fm (metals whose atomization is 3 to 5 valence La, Y, Gd, Si, B, Zr, T)
a total amount of the fluoride of a) 0 to 15%, and further, CuO is added to the base glass in an amount of 0.2 to CuO.
A fluorophosphate glass characterized by being added in an amount of 15% by weight. 2. P ⁵⁺ 11 to 43% in Cationic%, A
³⁺ 1 to 29%, R cation (divalent metal Ba,
Sr, Ca, Mg, Zn, Pb ion total amount) 14-5
0%, R'cation (monovalent metal Li, Na,
0 to 43% of total amount of K ion, R ″ cation (metal having a valence of 3 to 5 La, Y, Gd, Si, B, Zr, Ta)
A total amount of ions) 0 to 8% and Cu ²⁺ 0.5 to 13%, and further contains 17 to 80% of F ⁻ in anionic%. 3. A filter glass for color correction, comprising the fluorophosphate glass according to claim 1 or 2, and having a spectral transmittance characteristic of selectively absorbing a wavelength longer than 500 nm.