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2,466,505
Patented Apr. 5, 1949
I C E.
UNITED STATES
2,466,505
FLUOBGRATE GLASSES’
Kuan-Han Sun, Rochester, N; Y-., assignor to
Eastman Kodak Company, Rochester, N. ‘55., a
corporation of New Jersey:
No Drawing. ApplicationApril. 6,1946,
Serial No. 660,30’?
6 Claims.
((1106-47)
1
This invention relates to fluoborate optical
glass and particularly to such glass having a high
2
?uorides, are melted in a glass vessel of the type
mentioned‘to a fluid‘ liquid ?rst. For a 50 gram
indexgo?refraction, greater than 1.9, and high
melt, the melting takes about 5 minutes at 1200"
dispersion or low. Abbe’,v value, (1/), less than 25.
The glasses. herein described are primarily of
?uoborate type and contain in combined form:
boron,.?uorine;~ andloxygen; andk'alsortwo or more
Temperatures as low
1050’ C. may be used.
The ?uorides are then dumped in while the'melt
is stirred or shaken. The ?uorides dissolve‘
readily in the melt. After a few. minutes, the
?uid liquid may be shaken until a clear, trans
of the following elements: divalentdeadg'lbarium;
(3., longer for larger melts or lower temperatures.
lanthanum, titanium, and thorium. In the ex
parent, and fairly viscous liquid is obtained.
amples herein given the lead and titanium are 10 This liquid is then poured into a stainless mold
introduced as oxides, and barium, lanthanum,
previously heated to about 400-5000 C. The glass
and thorium as ?uorides; although, as is usual
is allowed to cool slowly, when clear and slightly
in glass making, the ingredients may be intro
yellowish glass is obtained. These glasses are
duced in other forms. As examples, boric acid,
durable against moisture attack.
HsBOs, may be used for 1301.5, and Pb30'4 for 15
The high silica glass vessel is usually not seri
PbO. Although a glass may be formed from a
ously attacked. The glass may be made also by
batch containing the various ingredients as ex
pouring the liquid glass after the complete solu
pressed in the batch formulas, these individual
tion of ?uorides from the vessel to a platinum
ingredients do not in fact exist as such in the
vessel. The liquid is then stirred to uniformity
?nal product. It is more nearly correct to corn 20
in the platinum vessel and poured to a mold.
sider these glasses as an irregular aggregate of
The invention herein disclosed is a speci?c
positive and negative ions. It is also convenient,
"form of the invention generically claimed in my
particularly in using “cationic” percentage or
copending application, Serial No. 646,681, ?led
electropositive atomic percentage, to adopt the
February 9, 1946, now Pat. No. 2,456,033 granted
form 301.5 instead of the equally empirical for
Dec. 14, 1948. Although the optical values here
mula 13203.
obtained fall below the line (nD=2.2-O.01 11)
A few typical examples are given in the follow
mentioned therein, and the amount of boron
ing table with composition of the batch by
oxide can be as low as 35 ionic per cent, whereas
weight percentage designated W and the cationic
in the examples of ‘my previous application the
or “male” percentage designated M. Because of 30 lowest is about 50, I consider the present disclo
the convention here adopted (B015 instead of
sures as within the broad conception of that
B203) which always has one cation per “mole,”
invention. It is to be further understood that
the cationic percentages are equal to the “mole”
the formulas given are by way of example and
percentages, and this is to be understood in inter
that the proportions of the ingredients may vary
preting the claims. The values of v and of an, 35 to a certain extent; that is, the amount of boron
the refractive index for the D line, are also
oxide may be considerably greater than in the
given and the atomic or ionic ratio of ?uorine to
examples, and the titanium ‘oxide may vary con
boron, F/ B.
siderably and may even be omitted entirely, and
A small addition of various compatible com
glass will result.
ponents is considered within the scope of the 40 a useful
When in the claims I refer to “?uoride selected
invention and, in fact, is frequently helpful to
from” enumerated ?uorides, I do not mean “a
prevent devitri?cation and to increase the chem
fluoride,” but intend to include one or more
ical stability.
?uorides.
Having thus described my invention, what I
claim is:
1. A ?uoborate optical glass having a value for
Example _______ _ _
nn greater than 1.9 and a value for 1/ less than 25
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l
comprising essentially in combined form ?uorine,
boron, and oxygen and at least two of the metals
selected from the group consisting of the follow
ing metals: barium, lanthanum, titanium, thori
um, and divalent lead, the mole percentage of
boron oxide being between 30 and 50 and the
mole percentage of ?uoride being between 3 and
15.
2. A ?uoborate optical glass consisting of the
fused, heat~reaction product of a batch compris
ing essentially in mole percentage: boron oxide,
In making these glasses, the ingredients, minus 60 between 35 and 50; lead oxide, between 30 and
In making the glasses, I preferably use a vessel
having a silica content greater than 96 per cent.
3
2,466,505
42; titanium oxide, between 10 and 20; and fluo
ride, between 3 and 15.
-
3. A ?uoborate optical glass consisting of th
fused, heat-reaction product of a batch com
4
oxide, 10 per cent; titanium oxide, 10 per cent;
lead oxide, 50 to 70 per cent; and thorium ?uo
ride, between 5 and 30 per cent.
6. A ?uoborate optical glass consisting of the
prising essentially in mole percentage: boron 5 fused,
heat-reaction product of a batch compris
oxide, between 35 and 50; lead oxide, between
ing essentially in mole per cent: boron oxide,
30 and 42; titanium oxide, between 10 and 20;
and ?uoride, between 4 and 15, of which between
4 and 15 is thorium ?uoride.
between 35 and 50 per cent; lead oxide, between
30 and 45 per cent; titanium oxide, between 10
and 20 per cent; and lanthanum fluoride, be
4. A ?uoborate optical glass consisting of the 10 tween
3 and 15 per cent.
fused, heat-reaction product of a batch compris
KUAN-HAN SUN.
ing essentially in percentage by weight: boron
oxide, 10 per cent; titanium oxide, 10 per cent;
REFERENCES CITED
lead oxide, 50 to 70 per cent; and ?uoride selected
The
following
references are of record in the
from the group consisting of the ?uorides of bari 15
?le of this patent:
um, lanthanum, thorium, and lead, and mixtures
thereof, 5 to 39 per cent; the ratio of fluorine to
UNITED STATES PATENTS
boron lying between 0.3 and 1.35, the glass having
Number
Name
Date
a value for 1113 greater than 1.9 and a value for 11
2,394,502
Weyl et a1 __________ __ Feb. 5, 1946
less than 25.
20
5. A fluoborate optical glass consisting of the
OTHER REFERENCES
fused, heat-reaction product of a batch compris
Ser.
No.
395,364,
Berger et al. (A. P. C.), pub
ing essentially in percentage by weight: boron
lished May 11, 1943.

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