Boron-free glass
The invention discloses boron-free neutral glasses having the composition (in % by weight, based on oxide) 65-72 SiO 2 , 11-17 Al 2 O 3 , 0.1-8 Na 2 O, 3-8 MgO, 4-12 CaO and 0-10 ZnO, a ratio CaO/MgO of 1.4 to 1.6, and having a hydrolytic resistance in accordance with DIN ISO 719 in class 1 and an acid resistance in accordance with DIN 12116 and an alkali resistance in accordance with DIN ISO 695 at least in class 2.
1. A glass containing at least the following constituents (in % by weight, based on oxide):
SiO 2
65-72
Al 2 O 3
11-17
Na 2 O
0.1-8
MgO
3-8
CaO
4.2-12
ZnO
0-10,
wherein the weight ratio CaO/MgO is 1.4 to 1.8;
wherein no B 2 O 3 , SrO, BaO, ZrO 2 and PbO are present, apart from unavoidable impurities;
wherein the glass is free of Li 2 O and K 2 O, apart from unavoidable impurities;
which has a hydrolytic resistance in hydrolytic class 1 in accordance with DIN ISO 719;
which has an acid resistance at least in acid class 2 in accordance with DIN 12116; and
which has an alkali resistance at least in alkali class 2 in accordance with DIN ISO 695.
2. A glass containing at least the following constituents (in % by weight, based on oxide):
SiO 2
65-72
Al 2 O 3
11-17
Na 2 O
0-8
MgO
3-8
CaO
4.2-12
ZnO
0.1-10,
wherein the weight ratio CaO/MgO is 1.4 to 1.8;
wherein the glass is free of Li 2 O and K 2 O, apart from unavoidable impurities;
wherein no B 2 O 3 , SrO, BaO, ZrO 2 and PbO are present, apart from unavoidable impurities;
which has a hydrolytic resistance in hydrolytic class 1 in accordance with DIN ISO 719;
which has an acid resistance in acid class 1 in accordance with DIN 12116; and
which has an alkali resistance at least in alkali class 2 in accordance with DIN ISO 695.
3. The glass according to claim 1 , wherein the Na 2 O content is 0.5 to 8% by weight.
4. The glass according to claim 1 , wherein the Na 2 O content is 2 to 6% by weight.
5. The glass according to claim 1 , wherein the CaO content is 7.1 to 12% by weight.
6. The glass according to claim 1 , wherein the ZnO content is 3 to 10% by weight.
7. The glass according to claim 1 , wherein the Al 2 O 3 content is 14 to 17% by weight.
8. The glass according to claim 1 , which has a working point T4 of less than 1320° C.
9. The glass according to claim 1 , which further contains 1 to 10% by weight of TiO 2 .
10. The glass according to claim 1 , which further contains 0.01 to 2% by weight of refining agents.
11. The glass according to claim 1 , which contains 0.01 to 2% by weight of at least one refining agent selected from the group consisting of As 2 O 3 , Sb 2 O 3 , SnO 2 , CeO 2 , Cl − , F − and SO 4 2 .
12. The glass according to claim 1 , which contains 0.01 to 2% by weight of at least one refining agent selected from the group consisting of As 2 O 3 , Sb 2 O 3 , SnO 2 , CeO 2 , Cl − , F − and SO 4 2 , wherein the maximum content of each of As 2 O 3 , Sb 2 O 3 , Cl − , F − and SO 4 2− is 1.5% by weight.
13. The glass according to claim 1 , which contains 0.01 to 2% by weight of at least one refining agent selected from the group consisting of As 2 O 3 , Sb 2 O 3 , SnO 2 , CeO 2 , Cl − , F − and SO 4 2 , wherein the maximum content of each of As 2 O 3 , Sb 2 O 3 , Cl − , F − and SO 4 2− is 1.5% by weight, and wherein the maximum content of each of SnO 2 and CeO 2 is 1% by weight.
14. A glass containing at least the following constituents (in % by weight, based on oxide):
SiO 2
65-72
Al 2 O 3
11-17
Na 2 O
0.5-8
MgO
3-8
CaO
4.2-12
ZnO
0-10,
F
0-2,
wherein the weight ratio CaO/MgO is 1.4 to 1.8;
wherein no B 2 O 3 , SrO, BaO, ZrO 2 and PbO are present, apart from unavoidable impurities;
wherein the glass is free of Li 2 O and K 2 O, apart from unavoidable impurities;
which has a hydrolytic resistance in hydrolytic class 1 in accordance with DIN ISO 719;
which has an acid resistance at least in acid class 2 in accordance with DIN 12116; and
which has an alkali resistance at least in alkali class 2 in accordance with DIN ISO 695.
15. The glass according to claim 14 , wherein the ZnO content is 3 to 10% by weight.
16. The glass according to claim 14 , wherein the Al 2 O 3 content is 14 to 17% by weight, and wherein the Na 2 O content is 2 to 8% by weight.
17. The glass according to claim 14 , which has a working point T4 of less than 1300° C.