Thin glass roll and method for producing same
A glass ribbon in the form of a glass roll is provided that is optimized with respect to the requirements of a long service life and at the same time compact dimensions. A bending radius on the inner side of the thin glass roll is determined by performing breakage tests on samples of the glass material, statistical parameters are determined on the basis of the breakage tests, and the statistical parameters are converted into a range of bending radii which meet the requirements on service life and the most compact dimensions possible of the thin glass roll.
1. A thin glass roll, comprising:
a thin glass ribbon having a length of at least 10 meters and a thickness of at most 200 micrometers, the thin glass ribbon being wound with an inner radius in a range from:
R
min
=
〈
R
〉
·
{
[
0.7
+
exp
(
s
〈
R
〉
·
0.053
-
2.3
)
]
·
(
2
-
e
-
t
)
}
to
R
max
=
〈
R
〉
·
{
[
3.4
+
exp
(
s
〈
R
〉
·
0.05
-
2.1
)
]
·
(
2
-
e
-
t
)
}
wherein
〈
R
〉
is
a
mean
value
and
s
=
1
N
-
1
∑
R
i
2
-
〈
R
〉
2
is a variance of a bending radii at break of a plurality N of samples made of the same glass material having the same thickness and the same glass edge quality as the glass material of the thin glass ribbon, wherein R i are the bending radii at which the respective samples break, t is a minimum time period, in days, the thin glass roll withstands without break, and wherein at least twenty samples of the thin glass are subjected to a bending stress until break, in order to determine the mean value <R>of the bending radii R i and the variance thereof, wherein the minimum time (t) is 5 days, and
wherein the thin glass ribbon has two opposite faces and two opposite longitudinal edges,
wherein the thin glass ribbon is wound so that a convexly curved face is that face for which samples cut out of the thin glass ribbon along the longitudinal edges and bent around the longitudinal edges in a common direction as the thin glass ribbon exhibits a smaller value of R min compared to samples bent in an opposite direction.
2. The thin glass roll as claimed in claim 1 , wherein the thin glass ribbon is a non-alkali borosilicate glass having a thickness of 50 micrometers, and wherein the thin glass roll comprises a core having a diameter between 30 millimeters and 83 millimeters.
3. The thin glass roll as claimed in claim 1 , further comprising a web material wound together with the thin glass ribbon so as to separate consecutive glass layers.
4. The thin glass roll as claimed in claim 1 , further comprising a relative variance, given by a ratio s/<R>at break of samples of the thin glass ribbon, that is less than 0.15.
5. The thin glass roll as claimed in claim 1 , wherein the thin glass ribbon comprises a chemically toughened alkali glass.
6. The thin glass roll as claimed in claim 5 , wherein the thin glass ribbon has an exchange depth of layer in a range from 1 to 10 micrometers.
7. The thin glass roll as claimed in claim 5 , wherein the thin glass ribbon has an exchange depth of layer in a range from 3 to 5 micrometers.
8. The thin glass roll as claimed in claim 1 , wherein the thickness is at most 100 micrometers and at least 5 micrometers.
9. The thin glass roll as claimed in claim 1 , wherein the thickness is less than 145 micrometers.
10. A thin glass roll, comprising:
a thin glass ribbon having a length of at least 10 meters and a thickness of at most 200 micrometers, the thin glass ribbon being wound with an inner radius in a range from:
R
min
=
〈
R
〉
·
{
[
0.7
+
exp
(
s
〈
R
〉
·
0.053
-
2.3
)
]
·
(
2
-
e
-
t
)
}
to
R
max
=
〈
R
〉
·
{
[
3.4
+
exp
(
s
〈
R
〉
·
0.05
-
2.1
)
]
·
(
2
-
e
-
t
)
}
wherein <R>is a mean value and
s
=
1
N
-
1
∑
R
i
2
-
〈
R
〉
2
is a variance of a bending radii at break of a plurality N of samples made of the same glass material having the same thickness and the same glass edge quality as the glass material of the thin glass ribbon, wherein R i are the bending radii at which the respective samples break, t is a minimum time period, in days, the thin glass roll withstands without break, and wherein at least twenty samples of the thin glass are subjected to a bending stress until break, in order to determine the mean value <R>of the bending radii R i and the variance thereof,
wherein the thin glass ribbon has two opposite faces and two opposite longitudinal edges, wherein the thin glass ribbon is wound so that a convexly curved face is that face for which samples cut out of the thin glass ribbon along the longitudinal edges and bent around the longitudinal edges in a common direction as the thin glass ribbon exhibits a smaller value of
R
min
=
〈
R
〉
·
[
0.7
+
exp
(
s
〈
R
〉
·
0.053
-
2.3
)
]
compared to samples bent in an opposite direction, wherein <R>is the mean value and
s
=
1
N
-
1
∑
R
i
2
-
〈
R
〉
2
is the variance of the bending radii at break of the samples, wherein R i are the bending radii at which the respective samples break, and wherein at least twenty samples of the thin glass are subjected to a bending stress until break, in order to determine the mean value <R>of the bending radii R i and the variance thereof.
11. The thin glass roll as claimed in claim 10 , wherein the thin glass ribbon is a non-alkali borosilicate glass having a thickness of 50 micrometers, and wherein the thin glass roll comprises a core having a diameter between 30 millimeters and 83 millimeters.
12. The thin glass roll as claimed in claim 10 , further comprising a web material wound together with the thin glass ribbon so as to separate consecutive glass layers.
13. The thin glass roll as claimed in claim 10 , further comprising a relative variance, given by a ratio s/<R>at break of samples of the thin glass ribbon, that is less than 0.15.
14. The thin glass roll as claimed in claim 10 , wherein the thin glass ribbon comprises a chemically toughened alkali glass.
15. The thin glass roll as claimed in claim 14 , wherein the thin glass ribbon has an exchange depth of layer in a range from 1 to 10 micrometers.
16. The thin glass roll as claimed in claim 14 , wherein the thin glass ribbon has an exchange depth of layer in a range from 3 to 5 micrometers.
17. The thin glass roll as claimed in claim 10 , wherein the thickness is at most 100 micrometers and at least 5 micrometers.
18. The thin glass roll as claimed in claim 10 , wherein the thickness is less than 145 micrometers.