JPS6033229A - Optical glass having high refractive index - Google Patents

Abstract

PURPOSE:To obtain optical glass with high meltability and high refractive index by using a glass compsn. having specified proportion of La2O3, TiO2, B2O3, and SiO2, and specified weight of total of B2O3 and SiO2. CONSTITUTION:Glass compsn. comprising by wt% 25-55 La2O3, 14-30 TiO2, 5-20 B2O3, and 4.5-12 SiO2, and 9.5-25 B2O3+SiO2 is prepd. If necessary, 0-20 GeO2 and 0-10 Al2O3 may be contained. Further, at least one among 0-20 Ta2O5, 0-20 Nb2O5, 0-20 at least one among CaO, SrO, BaO, ZnO, and PbO, 0-15 Y2O3, 0-15 Gd2O3, 0-15 Yb2O3, 0-15 WO3, and 0-13 Zr2O3 may be contained as modifying oxide, and 0-1 As2O3, and 0-1 Sb2O3 may be added as defoaming agent. By this compsn., optical glass having 1.90-2.10 refractive index and 22-35 Abbe' number is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical glass, and more particularly to optical glass with a high refractive index used in compact disc players using laser light, lenses for optical fiber connectors, and the like.

Previously, in Japanese Patent Publication No. 53-42330, B201
1-LazOs-Y2O2-TiOz (D4 component is essential, refractive index nd is 1.79 to 1.93.7-)
High refractive index glasses with a f number νd of 30-41 are known.

The present invention has better meltability than this conventional example, and
Refractive index nd is 1.90 to 2.10.7 Che number j/d
The object of the present invention is to provide an optical glass having an optical performance of F22 to F35.

TiO2 is not only a high refractive index component but also a component that increases the chemical durability of glass and improves its meltability.If it is contained in too large a quantity, TiO2 tends to devitrify. It is limited to % by weight (hereinafter simply referred to as %). On the other hand, in recent years, glass with a higher refractive index has been desired in order to improve the performance of compact disc player optical systems that use laser light and to downsize fiber connectors. Therefore, in the present invention, 5102, which suppresses devitrification and stabilizes the glass, is essential instead of the expensive Y2O3, which is an essential component in the conventional example, and by coexisting with this Sio2, Ti0z is further enlarged and high. It is characterized in that the refractive index does not cause devitrification.

More specifically, the high JFJA refractive index optical glass according to the present invention has the following composition range.

La20a 25-55% Ti()z 14-30% B2O35-20% 5iO24.5-12% However, the total amount of B2O5+5i02 is 9.5-25% Ta2
05 0-20% Nb2O5O~ 20' % WOa o ~1s% Zr020-13% Al2O80-10% A3208 0-1% SbzOg O~1% The reasons for limiting the fields containing each component will be explained below.

La2'g is a component that is intentionally included in order to achieve a high refractive index.
% or more, or if it exceeds 55%, devitrification tends to occur. As mentioned above, TiO2 is also a component to achieve a high refractive index and stabilize the glass, and if it is less than 14%, the desired high refractive index cannot be obtained, while if it exceeds 30%, it will devitrify. It becomes easier to do. B2O3 is a glass-forming oxide and is an essential component effective for suppressing devitrification; if it is less than 5%, devitrification tends to occur, and if it exceeds 20%, the desired high refractive index cannot be achieved. 5102 is a glass-forming oxide that suppresses devitrification and stabilizes the glass. If it is less than 4.5%, the glass viscosity is low, so it is easy to cause striae and devitrification. If it exceeds 12%, it will melt during melting. I will remain without doing so. If the total amount of B2O3 and 5102 exceeds 25%, the desired high refractive index cannot be obtained,
If it is less than 95%, devitrification tends to occur.

Furthermore, the following may be included as necessary. First, -G602 is a glass-forming oxide, and in order to stabilize the glass, it may be contained in an amount of 20% or less, or if it exceeds 20%, it will remain unmelted during melting.

Moreover, since it is an expensive component, if it is contained in a large amount, the raw material cost will be too high. A12011 is an intermediate oxide, and 1 is added to increase glass viscosity and improve devitrification resistance.
Although it may be contained in an amount of 0% or less, if it exceeds 10%, the desired high refractive index cannot be obtained.

Also, Ta205. Nb2O5, Cab, sro,
BaQ ZnQ l'bQ Y2O8GdzOi,
By containing modified oxides such as Yb20s, WOs, and ZrO2 within the above-mentioned predetermined ranges, it is possible to stabilize the glass, increase the refractive index, or improve the devitrification resistance. Ta2O6 and NbzOs can each be introduced in an amount of up to 20% to increase the refractive index and stabilize it, or if both exceed 20 Nb, they tend to devitrify. Ca,
Q SrQ BaO and ZnO can be introduced to stabilize the glass, and PbO can be introduced to stabilize the glass and increase the refractive index, but only one type or a combination of two or more of these can be introduced. If it exceeds 20%, devitrification tends to occur.

YzOs, GdzOs, YbzOg and WOs are
Although it is possible to introduce up to 15% to stabilize the glass and increase the refractive index, if it exceeds 15%, devitrification tends to occur. ZrO2 can also be introduced up to 13% to stabilize the glass and increase the refractive index, but if it exceeds this, the devitrification resistance will deteriorate.

Further, 320 g of A and 20 g of Sb may be introduced as foam removers at 1% or less each.

Examples of the present invention are shown in Table 1 below. Each of the examples was manufactured by charging a prepared batch of raw materials into a platinum crucible, maintaining it at 1400°C and stirring appropriately, and then casting it into a preheated mold and slowly cooling it, as in the past. Ru. In Table 1, "-" indicates that the component is not included.

(JA person T momme ω) Table 1

Claims (1)

[Claims] A high refractive index optical glass characterized by having the following composition range in weight%: La20g 25-55 TiO214-30 BzOa5-20 Sio2 4.5-12 However, the total amount of BzOs+SiO2 95~25Ta20s
O-2O Nl)205 0-20 GeO20-20 Cab, SrQ Bad, one or more combinations of two or more of ZnO and PbO O~20 Y2O110~15 Gd20s O~15 YbzOg O~ 15 wo8 0~15 ZrOz ' 0-13 A120a Q ~ 1O AS208 Q ~ l 5b20s 0, 1