Organic lens molds in inorganic glass and novel inorganic...

Details Organic lens molds in inorganic glass and novel inorganic... Organic lens molds in inorganic glass and novel inorganic...

2000-01-04

2002-08-20

Sample, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

C501S056000, C501S068000, C501S069000, C501S070000, C428S410000, C106S038900

Reexamination Certificate

active

06436858

ABSTRACT:

The principal object of the present invention is novel organic lens molds constituted wholly or in part of at least one specific inorganic glass. Said specific inorganic glass, when novel per se, constitutes a further object of the present invention.
The organic lenses are conventionally obtained by radical polymerization of a polymerizable composition cast between two complementary parts of a glass mold. At least one of these two parts has an internal surface which has an optical quality that confers an adequate surface quality to the cast lens.
Heretofore, the glasses used for constituting said organic lens molds have not in general been developed particularly to this end. Insofar as traditionally, the manufacturers of organic lenses are or have been glass lens manufacturers, the materials used for said molds for said organic lenses are in commercially available ophthalmic glasses. Such glasses have generally been treated thermally or chemically in order to strengthen their mechanical properties.
The inventors have summarized prior art inorganic glass compositions in columns 1 to 10 of the Table below. In double column 11 of said Table, the (novel and not novel) compositions of the glasses for the lens molds according to the invention are found, the composition that shall be reverted to in more detail a little further on in the text. The originality of the invention is demonstrated in considering said Table 1 and the comments relating thereto below.
TABLE 1
REFERENCE N°
1
2
3
4
5
11 INVENTION
Composition
US-A-
US-A-
US-A-
US-A-
US-A-
Glass for
Glass
(% by weight)
3,790,260
4,042,405
4,036,623
4,015,045
4,012,131
molds
per se
SiO
2
*
*
60-75
50-58
*
56-66
56-66
P
2
O
5
5-15
Al
2
O
3
1-5
0-5
0-7
7-17
(0.2-0.5)
2.5-10
2.5-4
B
2
O
3
0-2
0.5-7
0.5-7
Al
2
O
3
+ B
2
O
3
Li
2
O
0
0-5
0-5
0
0-3
0-3
Na
2
O
*
4-15
5-10
8-23
3-11
8-15
8-15
K
2
O
*
3-15
5-10
0-15
7-15
3-12
3-12
Total M
2
O
12-20
12-20
13-25
12-20
12-20
12-20
ZnO
*
0-15
2-8
*
2-12
2-12
MgO
*
0-4
0-2
0-6.5
*
0-3
0-3
ZnO + MgO
3-11
TiO
2
*
0-5
0-2
0-7
0-0.5
0-0.5
ZnO + MgO + TiO
2
10-20
ZrO
2
0-5
0-2
1-4.5
(1-5)
1-9
1-9
MgO + TiO
2
+ ZrO
2
CaO
0
0-5
0-10
(3-6)
0-1
0-1
MgO + Al
2
O
3
0.2-5
La
2
O
3
0-15
ZnO + La
2
O
3
+ CaO + MgO
8-15
MgO + CaO
2.5-10
TiO
2
= MgO + CaO
4-14
BaO
0-2
0-2
SrO
0-2
0-2
CaO + ZnO + MgO + BaO
SrO + BaO
MgO + CaO + SrO + BaO
0-5
0-5
MgO + CaO + SrO + BaO + ZnO + ZrO
2
NaCl
0-0.5
0-0.5
Sb
2
O
3
0-2
CeO
2
0-4.5
As
2
O
3
0-1.5
As
2
O
3
+ Sb
2
O
3
0-1
As
2
O
3
+ Sb
2
O
3
0-1
CTE (10
−7
/° C.)
80-95
Strain Point
>495° C.
Softening Point
<810° C.
Compression layer depth
>100 &mgr;m
>120 &mgr;m
>60 &mgr;m
>70 &mgr;m
REFERENCE N°
6
7
8
9
10
11 INVENTION
Composition
US-A-
EP-A-
DE-A-
GB-A-
US-A-
Glass for
Glass
(% by weight)
4,259,118
0,600,302
4,325,656
2,299,991
3,951,671
molds
per se
SiO
2
61.6-79.5
55-65
73-78
50-65
58-67
56-66
56-66
P
2
O
5
Al
2
O
3
2.5-14
4-10
1.5-4
5-15
4.5-8
2.5-10
2.5-4
B
2
O
3
1-10.5
5-20
9-12
0-6
0.5-7
0.5-7
Al
2
O
3
+ B
2
O
3
14-26
Li
2
O
0-3
0-4
0
0-3
0-3
Na
2
O
1.5-6
6-18
1-5
2-7
8.5-17
8-15
8-15
K
2
O
2-10
1-5
4-9
2-11
3-12
3-12
Total M
2
O
13-22
5-7
7-14
12-20
12-20
ZnO
0-12
0-1.5
1-2
0-10
2-12
2-12
MgO
0-3.19
0-4
0-3
*
0-3
0-3
ZnO + MgO
TiO
2
0-4
0-5
0-0.5
0-0.5
ZnO + MgO + TiO
2
ZrO
2
0-1.5
0-7
0.5-3
1-6
0-6.5
1-9
1-9
MgO + TiO
2
+ ZrO
2
0-10
CaO
0-4.2
1-3
*
0-1
0-1
MgO + Al
2
O
3
La
2
O
3
ZnO + La
2
O
3
+ CaO + MgO
MgO + CaO
TiO
2
= MgO + CaO
BaO
0-9.6
*
*
0-2
0-2
SrO
*
*
0-2
0-2
CaO + ZnO + MgO + BaO
3.2-17.9
SrO + BaO
MgO + CaO + SrO + BaO
12-25
0-5
0-5
MgO + CaO + SrO + BaO + ZnO + ZrO
2
6-10
NaCl
0-0.75
0-0.5
0-0.5
Sb
2
O
3
0-1
CeO
2
As
2
O
3
0-0.5
0-0.5
0-1
As
2
O
3
+ Sb
2
O
3
0-1
As
2
O
3
+ Sb
2
O
3
0-1
CTE (10
−7
/° C.)
33.9-53.7
70.8-96.7
30-60
80-95
Strain Point
Tg 566-
450-503° C.
>495° C.
660° C.
Softening Point
821-845° C.
688-706° C.
>830° C.
<810° C.
Compression layer depth
>10 &mgr;m
>70 &mgr;m
The ophthalmic glasses described in U.S. Pat. No. 3,790,260 (Ref. 1) are glasses of high strength, strong UV absorption (insofar as TiO
2
is a major constituent of it). They are free from ZrO
2
and CaO.
The U.S. Pat. No. 4,042,405 (Ref. 2) describes a phosphosilicate glass having a compression layer depth greater than 120 &mgr;m.
The U.S. Pat. No. 4,036,623 (Ref. 3) describes white glasses known as “crown” glasses which are strengthened by a specific treatment which includes:
a pre-heating of said glasses,
then, an immersion of these glasses into a molten KNO
3
bath at a temperature higher than the strain point of said glasses (advantageously at a temperature between 510 and 710° C.); this without inducing optical distortion.
Said white glasses do not contain any B
2
O
3
and generally comprise CaO.
The U.S. Pat. No. 4,015,045 (Ref. 4) describes glass compositions which are perfectly appropriate for producing flat glasses. Said compositions contain a significant amount of TiO
2
and do not contain any ZnO.
The U.S. Pat. No. 4,012,131 (Ref. 5) describes a glass for ophthalmic lenses, strengthened by an ion exchange technique, which has a compression layer depth greater than 60 &mgr;m. Said glass does not contain any ZnO.
The U.S. Pat. No. 4,259,118 (Ref. 6) describes thermally pre-stressable glasses which have a low linear coefficient of thermal expansion and high strain point and softening point. Said glasses do not contain any K
2
O.
The EP application EP-A-0 600 302 (Ref. 7) describes fast strengthenable boroaluminosilicate glass lenses (strengthenable in less than 4 hours). Said glass contains a large amount of B
2
O
3
, a small amount of ZnO (advantageously, it does not contain any ZnO) and can be ZrO
2
-free.
The German application DE-A-4 325 656 (Ref. 8) describes glass fire protection articles in a glass which is very rich in silica. No mention is made in this document of the applications of said glass in the optical and/or ophthalmic molds or lens fields.
Finally, the GB application GB-A-2 299 991 (Ref. 9) describes a chemically strengthened aluminosilicate glass for magnetic disks of low thickness. Said glass does not contain any B
2
O
3
, it contains Na
2
O at a maximal amount of 7% and the minimal amount of intervening MgO+CaO+BaO+SrO is more than 5%.
The use of these prior art inorganic glasses, which are different from those of the invention, has never been described nor suggested as molds for organic lenses.
The U.S. Pat. No. 3,951,671 (Ref. 10) describes glass compositions for use in making ophthalmic lenses or lens blanks which can subsequently be toughened by an ion-exchange process. The use of said glass compositions as molds for organic lenses is neither described nor suggested.
Within the particular context of molds for organic lenses, CORNING, SCHOTT and HOYA have especially used glasses known under the code-names:
QE-8092 (Danville), LJ-8361 (Danville), TRC 33 (Bagneaux) and BL, for CORNING (the first of these 4 glasses, referenced QE-8092, described in the U.S. Pat. No. 3,790,260, was placed on the market in the 1970's. It was created in order to have a better impact resistance than the second of said 4 glasses, referenced LJ-8361, itself placed on the market in the 1940's. To this end, said glass QE-8092 undergoes a chemical strengthening);
CHW-0991 and S-3 for SHOTT;
N-4 for HOYA.
Amongst these 7 glasses, only that referenced CHW-0991 is not a standard ophthalmic glass but is a glass developed specifically for preparing organic lens molds. Its properties are nevertheless very close to those of such a standard ophthalmic glass: QE-8092. The compositions of said two glasses—CHW-0991 and QE-8092—are in fact very close. Said two glasses contain significant amounts of TiO
2
(about 0.8%).
The same applies for the two other glasses referenced TRC 33 and S-3. They contain 1.5 and 0.6% TiO
2
respe

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