Heat-insulating member, low-melting glass composition, and sealing material paste

1. A heat-insulating member comprising:

a pair of substrates; and

an airtight sealing part,

wherein the airtight sealing part is formed in an outer peripheral part between the pair of substrates, a space being formed between the pair of substrates, the space being in a vacuum or reduced pressure state,

a sealing material that forms the airtight sealing part includes a low-melting glass composition comprising:

vanadium oxide;

barium oxide;

phosphorus oxide;

tungsten oxide; and

at least one additional oxide selected from the group consisting of TeO 2 , SrO, ZnO, K 2 O and Na 2 O,

wherein the low-melting glass composition contains, in terms of oxide contents, 35 to 47 mol % of V 2 O 5 , in which the following relational expressions are satisfied:

the mol % of V 2 O 5 +the mol % of BaO+the mol % of P 2 O 5 +the mol % of WO 3 ≥90 mol %; and

the mol % of V 2 O 5 >the mol % of BaO>the mol % of P 2 O 5 >the mol % of WO 3 .

2. The heat-insulating member according to claim 1 , wherein a spacer is arranged in the space.

3. The heat-insulating member according to claim 1 , wherein the pair of substrates are made of a glass.

4. The heat-insulating member according to claim 1 , wherein the low-melting glass contains, in terms of oxide contents, 35 to 47 mol % of V 2 O 5, 20 to 35 mol % of BaO, 15 to 25 mol % of P 2 O 5 , and 3 to 13 mol % of WO 3 .

5. The heat-insulating member according to claim 1 , wherein the low-melting glass further contains one or more selected from the group consisting of Mo, Te, Sr, Zn, K, and Na, and a total amount of them is 10 mol % or less in terms of oxide contents.

6. The heat-insulating member according to claim 1 , wherein the low-melting glass satisfies the following relational expression in terms of oxide contents:

37 mol % ≤the mol % of BaO+the mol % of P 2 O 5 ≤55 mol %.

7. The heat-insulating member according to claim 1 , wherein the low-melting glass satisfies the following relational expression in terms of oxide contents:

42 mol % ≤the mol % of V 2 O 5 +the mol % of WO 3 ≤55 mol %.

8. The heat-insulating member according to claim 1 ,

wherein the sealing material contains a filler particle,

the filler particle has a thermal expansion coefficient smaller than that of the low-melting glass, and

a content of the filler particle is 50 parts by volume or less based on 100 parts by volume of the low-melting glass.

9. The heat-insulating member according to claim 8 , wherein the filler particle is one or more selected from the group consisting of Zr 2 (WO 4 ) (PO 4 ) 2 , LiAlSiO 4 , Mg 2 Al 4 Si 5 O 18 , ZrSiO 4 , an SiO 2 glass, Al 6 Si 2 O 13 , and Nb 2 O 5 .

10. The heat-insulating member according to claim 1 , wherein the sealing material further contains a spherical bead for a spacer.

11. The heat-insulating member according to claim 1 that is airtightly sealed at a temperature of 420 to 500° C. by using the sealing material.

12. A low-melting glass composition comprising:

vanadium oxide;

barium oxide;

phosphorus oxide;

tungsten oxide; and

at least one additional oxide selected from the group consisting of TeO 2 , SrO, ZnO, K 2 O and Na 2 O,

wherein the low-melting glass composition contains in terms of oxide contents, 35 to 47 mol % of V 2 O 5 , in which the following relational expressions are satisfied:

the mol % of V 2 O 5 +the mol % of BaO+the mol % of P 2 O 5 +the mol % of WO 3 ≥90 mole %; and

the mol % of V 2 O 5 >the mol % of BaO>the mol % of P 2 O 5 >the mol % of WO 3 .

13. The low-melting glass composition according to claim 12 , containing, in terms of oxide contents, 20 to 35 mol % of BaO, 15 to 25 mol % of P 2 O 5 , and 3 to 13 mol % of WO 3 .

14. The low-melting glass composition according to claim 12 , further containing one or more selected from the group consisting of Mo, Te, Sr, Zn, K, and Na, in which a total amount of them is 10 mol % or less in terms of oxide contents.

15. The low-melting glass composition according to claim 12 , wherein the following relational expression is satisfied in terms of oxide contents:

37 mol % ≤the mol % of BaO+the mol % of P 2 O 5 ≤55 mol %.

16. The low-melting glass composition according to claim 12 , wherein the following relational expression is satisfied in terms of oxide contents:

37 mol % to 42 mol %≤the mol % of V 2 O 5 +the mol % of WO 3 ≤55 mol %.

17. A sealing material paste containing:

a powder particle of the low-melting glass composition according to claim 12 ; and

a filler particle having a thermal expansion coefficient smaller than that of the low-melting glass composition,

wherein a content of the filler particle is 50 parts by volume or less based on 100 parts by volume of the low-melting glass composition.

18. The sealing material paste according to claim 17 , wherein the filler particle is one or more selected from the group consisting of Zr 2 (WO 4 ) (PO 4 ) 2 , LiAlSiO 4 , Mg 2 Al 4 Si 5 O 18 , ZrSiO 4 , an SiO 2 glass, Al 6 Si 2 O 13 , and Nb 2 O 5 .

19. The sealing material paste according to claim 17 , further containing a spherical glass bead for a spacer.

20. The sealing material paste according to claim 19 , wherein a content of the spherical glass bead is 1 part by volume or less based on 100 parts by volume of the low-melting glass composition.

21. The heat-insulating member according to claim 1 , wherein a softening point of the low-melting glass is less than or equal to 446° C.