HIGH-TRANSMISSION GLASS
A glass includes, in mass percentage on an oxide basis, 50 to 85% of SiO 2 , 0 to 10% of B 2 O 3 , 1 to 20% of Na 2 O, and 20% or less of K 2 O, and Sb 2 O 3 is substantially not contained. A total content (Ni+Cr) is more than 0 ppm by mass and 1.2 ppm by mass or less. A total iron oxide (t-Fe 2 O 3 ) in terms of Fe 2 O 3 , a ratio (Na 2 O/Al 2 O 3 ) and a total content (Al 2 O 3 +K 2 O) fall within specific ranges, respectively. The contents of each component satisfy a specific relationship.
1 . A glass comprising from 5 to 90 ppm by mass of a total iron oxide (t-Fe 2 O 3 ) in terms of Fe 2 O 3 , wherein
contents expressed in mass percentage on an oxide basis are SiO 2 : from 50 to 85%, B 2 O 3 : from 0 to 10%, Na 2 O: from 1 to 20%, and K 2 O: 20% or less, and Sb 2 O 3 is substantially not contained,
a total content (Ni+Cr) of Ni and Cr is more than 0 ppm by mass and 1.2 ppm by mass or less,
a ratio (Na 2 O/Al 2 O 3 ) of the content of Na 2 O to the content of Al 2 O 3 , expressed in mass percentage on the oxide basis, is 0.5 or more and 50 or less,
a total content (A1203+K 2 O) of Al 2 O 3 and K 2 O, expressed in mass percentage on the oxide basis, is 1% or more and 20% or less, and
the contents of each component satisfy the following formula (1):
P Fe =[Fe 3+ ]×(4.5×[MgO]+3.9×[CaO]+1.7×[SrO]+1.9×[BaO]+2.7×[Al 2 O 3 ]−0.3×[Na 2 O]−1.5×[K 2 O]−1.7×[Li 2 O])≤3000 (1)
wherein [Fe 3+ ] represents a content expressed in ppm by mass and the others represent the contents expressed in mass percentage on the oxide basis.
2 . The glass according to claim 1 , wherein the content of Ni is more than 0 ppm by mass and 0.8 ppm by mass or less.
3 . The glass according to claim 1 , wherein the content of Cr is 1.0 ppm by mass or less.
4 . The glass according to claim 1 , wherein the content of CeO 2 on the oxide basis is 500 ppm by mass or less.
5 . The glass according to claim 1 , wherein the content of Al 2 O 3 , expressed in mass percentage on the oxide basis, is more than 0% and 14% or less.
6 . The glass according to claim 1 , wherein the content of SnO 2 , expressed in mass percentage on the oxide basis, is more than 0% and 1% or less.
7 . The glass according to claim 6 , wherein the content of Al 2 O 3 , expressed in mass percentage on the oxide basis, is from 10 to 14%.
8 . The glass according to claim 1 , comprising from 10 to 65 ppm by mass of the total iron oxide (t-Fe 2 O 3 ) in terms of Fe 2 O 3 .
9 . The glass according to claim 1 , wherein the contents of each component satisfy the following formula (2):
P Ni =[Ni]×(2.2×[MgO]+1.9×[CaO]+1.1×[SrO]+1.1×[BaO])≤21 (2)
wherein [Ni] represents the content expressed in ppm by mass and the others represent the contents expressed in mass percentage on the oxide basis.
10 . The glass according to claim 1 , wherein the contents of each component satisfy the following formula (3):
P Cr =[Cr]×(1.9×[MgO]+1.3×[CaO]+0.6×[SrO]+0.5×[BaO])≤21 (3)
wherein [Cr] represents the content expressed in ppm by mass and the others represent the contents expressed in mass percentage on the oxide basis.
11 . The glass according to claim 10 , wherein a total (P Ni +P Cr ) of P Ni represented by the following formula (2) and the P Cr represented by the formula (3) is 25 or less:
P Ni =[Ni]×(2.2×[MgO]+1.9×[CaO]+1.1×[SrO]+1.1×[BaO])≤21 (2)
wherein [Ni] represents the content expressed in ppm by mass and the others represent the contents expressed in mass percentage on the oxide basis.
12 . The glass according to claim 1 , wherein an average value of internal transmittance (α) at a wavelength of 430 to 450 nm at an optical path length of 50 mm is 95.5% or more.
13 . The glass according to claim 1 , wherein an amount of divalent iron (Fe 2+ ) in terms of Fe 2 O 3 is more than 0 ppm by mass and 15 ppm by mass or less.
14 . The glass according to claim 1 , wherein contents of alkaline earth metal oxides, expressed in mass percentage, satisfy the relationship of {(CaO+SrO+BaO)−MgO}≥−8.
15 . The glass according to claim 1 , wherein a minimum value of internal transmittance (β) at a wavelength of 400 to 700 nm at an optical path length of 50 mm is 94.5% or more and a difference between a maximum value of the internal transmittance (β) and the minimum value of the internal transmittance (β) is 5% or less.
16 . The glass according to claim 1 , wherein a value of internal transmittance spectrum flatness A of the glass at a wavelength of 400 to 700 nm, determined according to the following formula (4), is 0.95 or more:
A =min( X,Y,Z )/max( X,Y,Z ) (4)
wherein X, Y and Z are values represented respectively by X=Σ(S(λ)×x(λ)), Y=Σ(S(λ)×y(λ)) and Z=Σ(S(λ)×z(λ)) using isochromatic functions x(λ), y(λ) and z(λ) in an XYZ color system based on MS Z8701: 1999 and internal transmittance S(λ) at a wavelength of 400 to 700 nm at an optical path length of 200 mm, and the min(X,Y,Z) represents the minimum value out of X, Y and Z and the max(X,Y,Z) represent the maximum value out of X, Y and Z.
17 . A glass sheet comprising the glass according to claim 1 , wherein the glass sheet has a length of at least one side of 140 mm or more and a thickness of 0.5 mm or more
18 . A light guide plate comprising the glass according to claim 1 .