JPS61146732A - Glass having high refractive index and high dispersion - Google Patents

Abstract

PURPOSE:To obtain high refractive index and high dispersion glass having superior meltability, mechanical strength and chemical durability by incorporating together Nb2O5 and TiO2 acting as the high refractive index and high dispersion in P2O5-B2O3-Al2O3 series glass. CONSTITUTION:Materials are weighed and mixed so as to obtain the glass composed of, by wt%, 22-60 Nb2O5, 18-38 P2O5, 6-25 TiO2, 3-11 Al2O3, 1-10 B2O3, 0-2 Li2O, 0-13 Na2O, 0-19 K2O (wherein, 5-19 content of Li2O+ Na2O+K2O), 0-12 PbO, 0-15 WO3, 0-5 Ta2O5, and 0.01-1 As2O3. The resultant mixture is then heated and melted, then cooled to obtain the desired glass having high refractive index and high dispersion. The refractive index and Abbe number of the resultant glass are more dispersive than those indicated by the line that connects (1.98, 18.5)-(1.9, 21)-(1.75, 25)-(1.65, 30).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical glass, and more particularly, to an optical glass having a refractive index N
d is 1.69 to 1.97. The present invention relates to a high refractive index and high dispersion glass having an Abbe number νd in the range of 17 to 30.

Conventionally, in JP-A-55-51732, the refractive index Nd is 1.68 to 1.84 and the Atsube number νd is 22 to 3.
No. 2 high refractive index, high dispersion glasses have been proposed. This glass is made of a silicate system, and has a large dispersion relative to its refractive index, but when the refractive index exceeds 1.80, the dispersion becomes somewhat low, and the liquidus temperature is high, resulting in poor meltability and resistance to devitrification. It had the disadvantage of being inferior in gender.

Furthermore, Japanese Patent Publication No. 55-37500 and No. 56-40
Although Publication No. 094 discloses a phosphate-based glass with high refractive index and high dispersion, it cannot obtain the high refractive index dispersion that is the objective of the present invention, has poor mechanical strength, and has low liquidus temperature. The disadvantage was that the melting properties were high and the meltability was poor.

The present invention has been made in view of the drawbacks of the above-mentioned conventional example, and its purpose is to reduce (Nd, νd) to (1,9B, 18.5
) −(1,90,21) −(1,75,25) −(
It is an object of the present invention to provide a high refractive index, high dispersion glass that has higher dispersion than the line connecting 1, 69, and 30), has excellent meltability, and is also excellent in mechanical strength and chemical durability.

In order to achieve the above object, the high refractive index and high dispersion glass according to the present invention is characterized by comprising the following composition range in weight percent.

Nb2O522-60% by weight P2O518-38# Ti026-25 AJzOa 3-11 ・8203
1~lO〃 1i20 0~2 # Naz0 0~13 #20
0-19 #However, L i 20+Na
Content of 2O-1-KzO: 5-19% by weight pbo
o~12# W03 0~15 1 TazOs Q~5 "A3203
0.01-1 # Each component will be explained below. First, P2O5 is a glass-forming oxide, and A
By using in combination with 12os and B2O3,
This is useful for introducing a large amount of NbzOs, which is a high refractive index and high dispersion component. However, if the lower limit is exceeded, devitrification resistance deteriorates, and if the upper limit is exceeded, the optical performance aimed at by the present invention cannot be obtained, and chemical durability deteriorates.

B2O3 is useful for introducing a large amount of Nb205 in combination with P2O5, but if the lower limit is exceeded, the liquidus temperature will increase and the meltability will deteriorate, while if the upper limit is exceeded, phase separation will occur and chemical physical durability and mechanical strength deteriorate.

AJzOa is a component that, when introduced in an appropriate amount, lowers the liquidus temperature and strengthens the glass structure to increase mechanical strength. If the lower limit of 3 to 11% by weight is exceeded, the above-mentioned effect cannot be obtained sufficiently, and if the upper limit is exceeded, the liquidus temperature becomes high and the meltability deteriorates.

Nb+Os is a high refractive index and high dispersion component, P2O5-B
Although it can be introduced in large quantities into the 203-A12os system, 2
If the lower limit of 2 to 60% by weight is exceeded, the chemical performance targeted by the present invention cannot be obtained, while if the upper limit is exceeded, the liquidus temperature will increase and the devitrification resistance will deteriorate.

T i O2 is also a high refractive index and high dispersion component, and NbzOs
When used in combination with a large amount of , it helps to lower the liquidus temperature. If this exceeds the lower limit of 6 to 25% by weight, the liquidus temperature will increase and the dispersion will decrease,
If the upper limit is exceeded, the liquidus temperature will increase and the coloration will deteriorate significantly.

Li2O, NazO, and Ni2O are used to lower the liquidus temperature and introduce a large amount of Nb zOs, respectively. However, if the content exceeds the lower limit of 5 to 19% by weight, the above-mentioned effects cannot be sufficiently obtained, and if the content exceeds the upper limit, the desired optical performance cannot be obtained and chemical durability deteriorates. Further, the upper limit of LizO, NazO, and 20 is set at 2.13.19% by weight, respectively. The reason for this is that if the upper limit is exceeded, the desired optical performance cannot be obtained, and in addition, the viscosity is reduced and the chemical durability is also deteriorated. Also, Li 20. Na2O,
By appropriately combining and and 20, it is possible to further lower the liquidus temperature than when used alone, and also produces favorable results for coloring.

AszOi is essential as a clarifying and decolorizing agent in phosphate glasses such as those of the present invention.
~1% by weight is essential.

In order to further lower the liquidus temperature and obtain a high refractive index and high dispersion, PbO,
WOa, Ta 206 wo 12, 15.5 respectively
Up to % by weight can be introduced. Although pbo is an effective component for lowering the liquidus temperature and achieving high refractive index and high dispersion, if it exceeds 12% by weight, it will turn yellow.

Although WOs and Ta205 are both high refractive index components, if their content exceeds 15.5% by weight, the liquidus temperature becomes high.

Furthermore, in order to stabilize the glass while maintaining a high refractive index, MgO, Ca1m SrO, BaO, ZnO, etc. (
7) Fluorescent earth metal oxides may be introduced in a content of one or more kinds up to 0 to 10% by weight f1%. Here, if this content exceeds the upper limit, the desired optical performance cannot be obtained.

Furthermore, when fluorine is introduced within the range of 0 to 1% by weight, it has the effect of lowering the liquidus temperature.

Table 1.2 below shows the composition and optical performance of the samples 1 to 12 according to the present invention. In the table, - indicates that the component is not included.

Claims (1)

[Claims] A high refractive index, high dispersion glass characterized by comprising the following composition range in weight%: Nb_2O_5 22-60% by weight P_2O_5 18-38〃 TiO_2 6-25〃 Al_2O_3 3-11〃 B_2O_3 1 ~10〃 Li_2O 0~2〃 Na_2O 0~13〃 K_2O 0~19〃 However, total amount of Li_2O + Na_2O + K_20 5~
19% by weight PbO 0-12〃 WO_3 0-15〃 Ta_2O_5 0-5〃 As_2O_3 0.01-1〃.