Boron-poor neutral glass with titanium and zirconium oxides
The neutral glass according to the present invention is characterized by excellent hydrolytic stability, a relatively low processing temperature and low content of boron oxide. Here, the neutral glass has the following composition, in percent by weight based on oxide content: SiO 2 , 70-79; B 2 O 3 , 0-<5; Al 2 O 3 , <5; ZrO 2 , 0.5-<5; TiO 2 , 0.5-6; Na 2 O, 1-6; K 2 O, 3 to 8; and Li 2 O, 0-0.5, wherein a total amount of SiO 2 and B 2 O 3 is less than 83 percent by weight.
1. A neutral glass having high hydrolytic stability with a composition comprising, in percent by weight based on oxide content:
SiO 2
70 to 79
B 2 O 3
0 to <5
Al 2 O 3
1 to <5
ZrO 2
0.5 to <5
TiO 2
0.5 to 6
Na 2 O
1 to 6
K 2 O
3 to 8
Li 2 O
0 to 0.5,
wherein a total amount of SiO 2 and B 2 O 3 in the composition is less than 83 percent by weight.
2. The neutral glass according to claim 1 , wherein the composition comprises, in percent by weight base on oxide content:
ZrO 2
1 to <5
TiO 2
1 to 6.
3. The neutral glass according to claim 1 , wherein the composition comprises in percent by weight based on oxide content:
B 2 O 3
0 to 4.5.
4. The neutral glass according to claim 1 , wherein the composition comprises a sum total amount of alkali metal oxides between >9 percent by weight and 14 percent by weight.
5. The neutral glass according to claim 1 , wherein the composition comprises a sum total amount of ZrO 2 and TiO 2 of at most 10% by weight.
6. The neutral glass according to claim 1 , wherein the composition comprises a sum total amount of ZrO 2 and TiO 2 that is greater than 2.5 percent by weight.
7. The neutral glass according to claim 1 , wherein a weight ratio of ZrO 2 to TiO 2 is in a weight range between 1.5:1 and 0.6:1.
8. The neutral glass according to claim 1 , wherein the composition does not contain B 2 O 3 .
9. The neutral glass according to claim 1 , wherein the composition comprises ZrO 2 in an amount of at least 2.5 percent by weight.
10. The neutral glass according to claim 1 , wherein the composition comprises TiO 2 in an amount of at least 2.5 percent by weight.
11. The neutral glass according to claim 1 , having a hydrolytic stability according to ISO 719 that is no more than 15 μg per g.
12. The neutral glass according to claim 1 , having a processing temperature of at most 1260° C.
13. The neutral glass according to claim 12 , wherein the processing temperature is at most 1220° C.
14. A method of producing a neutral glass, said method comprising the steps of:
a) mixing glass components,
b) melting the glass components to form a glass melt, and
c) optionally refining the glass melt;
whereby a neutral glass with the composition according to claim 1 is formed by the method.
15. A primary pharmaceutical packaging material comprising the neutral glass according to claim 1 .
16. A food packaging material comprising the neutral glass according to claim 1 .