Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
242 words
Glass, suitable as near-portion material for fusion with phototropic far-portion glass for multifocal spectacle lenses, having a linear thermal expansion coefficient between 45 and 58 × 10 - 7 /° C, a refractive index of n d ≧ 1.60, a speed of crystallization of less than 0.5 μ/min. and the following composition: ______________________________________
SiO.sub.2 10.0 - 20.0 % by weight
B.sub.2 O.sub.3
15.0 - 23.0 % by weight
PbO >26.0 - 30.0 % by weight
ZnO 3.0 - 5.0 % by weight
La.sub.2 O.sub.3
6.0 - 10.0 % by weight
Al.sub.2 O.sub.3
12.0 - 17.0 % by weight
ZrO.sub.2 0.5 - 3.0 % by weight
TiO.sub.2 0.2 - 3.0 % by weight
K.sub.2 O 0.1 - 2.0 % by weight
Na.sub.2 O 0.1 - 2.0 % by weight
Li.sub.2 O 0.1 - 4.0 % by weight
______________________________________ with the provision that: ______________________________________
sum of SiO.sub.2 + B.sub.2 O.sub.3 is
30.0 - 40.0 %
by weight
sum of the alkali oxides is
0.2 - 3.0 %
by weight
sum of Al.sub.2 O.sub.3 + La.sub.2 O.sub.3 is
19.0 - 27.0 %
by weight
sum of the alkaline earth
oxides is 3.0 - 8.0 %
by weight, MgO
being less than
5 % by weight
and BaO
being 3 - 8 %
by weight
sum of ZnO + ZrO.sub.2 + TiO.sub.2 is
3.0 - 6.0 %
by weight
sum of the oxides of Bi,
Ta, Nb, W is 0 - 5.0 %
by weight.
______________________________________
Claim 2
Dependent Claim
242 words
Glass, suitable as near-portion material for fusion with phototropic far-portion glass for multifocal spectacle lenses, having a linear thermal expansion coefficient between 45 and 58 × 10 - 7 /° C, a refractive index of n d ≧ 1.60, a speed of crystallization of less than 0.5 μ/min. and the following composition: ______________________________________
SiO.sub.2 10.0 - 20.0 % by weight
B.sub.2 O.sub.3
15.0 - 23.0 % by weight
PbO >26.0 - 30.0 % by weight
ZnO 3.0 - 5.0 % by weight
La.sub.2 O.sub.3
6.0 - 10.0 % by weight
Al.sub.2 O.sub.3
12.0 - 17.0 % by weight
ZrO.sub.2 0.5 - 3.0 % by weight
TiO.sub.2 0.2 - 3.0 % by weight
K.sub.2 O 0.1 - 2.0 % by weight
Na.sub.2 O 0.1 - 2.0 % by weight
Li.sub.2 O 0.1 - 4.0 % by weight
______________________________________ with the provision that: ______________________________________
sum of SiO.sub.2 + B.sub.2 O.sub.3 is
30.0 - 40.0 %
by weight
sum of the alkali oxides is
0.2 - 3.0 %
by weight
sum of Al.sub.2 O.sub.3 + La.sub.2 O.sub.3 is
19.0 - 27.0 %
by weight
sum of the alkaline earth
oxides is 3.0 - 8.0 %
by weight, MgO
being less than
5 % by weight
and BaO
being 3 - 8 %
by weight
sum of ZnO + ZrO.sub.2 + TiO.sub.2 is
3.0 - 6.0 %
by weight
sum of the oxides of Bi,
Ta, Nb, W is 0 - 5.0 %
by weight.
______________________________________
Claim 3
Dependent Claim
69 words
A material according to claim 1, further containing phototropicity-causing substances, as follows: ______________________________________
Ag.sub.2 O 0.1 - 1.8 % by weight
CuO 0 - 0.05% by weight
CoO 0 - 0.01% by weight
______________________________________ and halogens, which replace the oxygen in the anion portions, ______________________________________
Cl 0.2 - 4.5 % by weight
Br + I 0 - 4.0 % by weight
F 0 - 4.0 % by weight.
______________________________________
Claim 4
Dependent Claim
17 words
A glass according to claim 1 wherein the concentration of PbO is at least 26.4% by weight.
Claim 5
Dependent Claim
17 words
A glass according to claim 1 wherein the concentration of PbO is at least 26.6% by weight.
Claim 6
Dependent Claim
17 words
A glass according to claim 1 wherein the concentration of PbO is 26.8 to 29.5% by weight.
Claim 7
Dependent Claim
17 words
A glass according to claim 1 wherein the concentration of PbO is 26.8 to 29.3% by weight.
Claim 8
Dependent Claim
20 words
A glass according to claim 1 wherein the La 2 O 3 content is not more than 9.8% by weight.
Claim 9
Dependent Claim
20 words
A glass according to claim 1 wherein the La 2 O 3 content is not more than 9.7% by weight.
Claim 10
Dependent Claim
19 words
A glass according to claim 1 wherein the La 2 O 3 content is 6.5 to 9.5% by weight.
Claim 11
Dependent Claim
19 words
A glass according to claim 1 wherein the La 2 O 3 content is 6.9 to 9.0% by weight.