THIN SHEET GLASS COMPOSITE AND METHOD OF STORING THIN SHEET GLASS

Abstract

The invention relates to a method of storing a thin sheet glass film (10). According to the invention, the thin sheet glass film (10) is held at two sides, at least one side of the thin sheet glass film (10) is coated over its entire surface with a fluid coating material (20) comprising at least one drying agent, the coating material (20) sets to form a solid polymeric coating, and the coated thin sheet glass film (10) is rolled up for storage.

Claims

1. A method for storing a thin sheet glass film wherein, according to the method, the thin sheet glass film is held at two sides, at least one side of the thin sheet glass film is coated with a fluid coating material comprising at least one drying agent present upon its surface, the coating material on the at least one side of the thin sheet glass film sets to form a solid polymeric coating, and wherein the coated thin sheet glass film is rolled up for storage.

2. The method according to claim 1, wherein the coated thin sheet glass film is rolled up in such a way that the radial outer side of the rolled up thin sheet glass film is coated with the polymeric coating.

3. The method according to claim 1, wherein, a solution, dispersion, or melt of the polymer is used as a coating material.

4. The method according to claim 1, wherein the structural components of polymers are applied to the at least one side of the thin sheet glass film, and energy is transmitted to the applied structural components, and the structural components react to form a coating material.

5. The method according to claim 1, wherein the coating material has a viscosity of more than 1 mPa.Math.s and less than 10.sup.8 Pa.Math.s.

6. The method according to claim 1, wherein and additional, permeating-inhibiting barrier layer is applied to the side of the polymeric coating facing away from the thin sheet glass film.

7. The method according to claim 1, wherein the polymeric coating is peeled from the at least one side of the thin sheet glass film.

8. The method according to claim 1, wherein the one side of the thin sheet glass film is coated with a silane-containing coating material and the polymeric coating remains permanently on the thin sheet glass film.

9. The method according to claim 1, wherein the polymeric coating is reversibly bonded to the thin sheet glass film.

10. A rolled up thin sheet glass composite which comprises: a thin sheet glass film having two sides and a polymeric coating over its entire surface comprising at least one drying agent, which sets on at least one of the sides and is in direct contact with at least one side of the thin sheet glass film over its entire surface and is present upon the radial outer side of the thin sheet glass film.

11. A rolled up thin sheet glass composite according to claim 10, which further comprises an additional permeation-inhibiting barrier layer (30) is present upon the entire surface of a side of the polymeric coating facing away from the thin sheet glass film (10).

12. The method according to claim 5, wherein the coating material has a viscosity of more than 1 mPa.Math.s and less than 10.sup.5 Pa.Math.s.

13. The method according to claim 12, wherein the coating material has a viscosity of more than 1 mPa.Math.s and less than 10 Pa.Math.s.

Description

[0090] The invention is described by means of two embodiments in five figures. The figures show the following:

[0091] FIG. 1 shows a thin sheet glass composite with a permeation-inhibiting coating that can be rolled up according to the invention,

[0092] FIG. 2 shows a thin sheet glass composite that can be rolled up,

[0093] FIG. 3a shows a principle diagram of the bent thin sheet glass composite in the two point bending test,

[0094] FIG. 3b shows a schematic view of the strain gauge arranged on the thin sheet glass composite,

[0095] FIG. 3c shows a schematic side view of the bent thin sheet glass.

[0096] Various coatings filled with drying agents were produced.

Coating Materials

[0097] The following coating materials 20 are used to form the coating according to the invention:

[0098] B1: Radiation-crosslinkable acrylate coating material:

TABLE-US-00001 70 parts CN307 POLYBUTADIENE DIMETHACRYLATE manufactured by Sartomer with a viscosity of 750 mPa .Math. s at 60 C. 20 parts SR833S TRICYCLODECANE DIMETHANOL DIACRYLATE manufactured by Sartomer 5 parts Irgacure 500 Photoinitiator manufactured by BASF composed of a mixture of 50% 1-hydroxycyclohexylphenylketone and benzophenone in a 1:1 ratio 5 parts Ebecryl Amino-functionalized acrylate coinitiator 7100

[0099] B2: Radiation-crosslinkable acrylate coating material:

TABLE-US-00002 85 parts Ebecryl 184 Urethane acrylate oligomer manufactured by Cytec containing HDDA 5 parts HDDA Hexane diol diacrylate manufactured by Cytec 5 parts lrgacure 500 Photoinitiator manufactured by BASF composed of a mixture of 50% 1- hydroxycyclohexylphenylketone and benzophenone in a 1:1 ratio 5 parts Ebecryl 7100 Amino-functionalized acrylate coinitiator

[0100] B3: Reversible polyisobutylene (PIB) coating material

TABLE-US-00003 100 parts Oppanol B 150 PIB from BASF, Mn = 425.000 g/mol

[0101] A solution with a PIB content of 10 wt. % is produced. Toluene is used as a solvent.

[0102] B4: PVDC coating material

TABLE-US-00004 100 parts Ixan SGA1 PVDC resin manufactured by Solvay

[0103] A solution with a PVDC content of 25 wt. %. methyl ether ketone is used as a solvent.

[0104] In order to produce layers for the determination of the water vapor permeation rate of the coating materials B1-B4, the various coating materials are applied to a polyether sulfone membrane manufactured by Sartorius by means of a laboratory application device in a (dry) layer thickness of approx. 50 m. The membrane is highly permeable to water vapor. The use of the highly-permeable membrane ensures that only the water vapor permeation rate of the coating is measured.

[0105] Samples with the coating materials B1 and B2 are crosslinked in a UV Cube manufactured by Hoenle (mercury medium pressure emitter) with a UV-C-dose of 200 mJ/cm.sup.2 (250 to 260 nm band).

[0106] Drying of the coating materials B3 and B4 is carried out in each case at 120 C. for 30 min in a laboratory drying cabinet.

[0107] The water vapor permeation rate (WVTR) is measured at 38 C. and 90% relative humidity according to ASTM F-1249. The indicated value is the average of two measurements.

TABLE-US-00005 Name WVTR [g/m.sup.2 d] B1 34 B2 286 B3 8 B4 3

[0108] The following drying agents are used:

TABLE-US-00006 Name Description Brand name Supplier G1 Calcium oxide Calcium oxide nanopowder Sigma-Aldrich G2 Zeolite 3A Purmol 3 STH Zeochem

[0109] The drying agents are incorporated into the coating materials B1-B4 using a high-speed dispersion disk of a laboratory centrifuge. The coating materials are first dried by means of approx. 1 mm zeolite spheres, which are again filtered out before the coating process.

[0110] As a thin sheet glass film, a glass of the type D263 T eco manufactured by Schott, Mainz with a thickness of 70 m and a length of 100 mm was used, and the width was also 100 mm.

[0111] Coating onto the thin sheet glass film 10 is carried out analogously to coating onto the membrane. As a permeation-inhibiting additional barrier layer 30, in example V9 a film provided with an inorganic barrier layer manufactured by Toppan is laminated onto the coating B2 before curing. UV irradiation is carried out through the film.

TABLE-US-00007 Thickness WVTR Name Description Brand name Supplier [m] [g/m.sup.2d] T1 polyester film with GX-P-F Toppan 30 0.13 organic barrier Printing layer

[0112] As a comparison example, a coating is produced with the coating material 20 B2 produced that contains no drying agent and has a water vapor permeation rate of more than 50 g/m.sup.2d.

TABLE-US-00008 TABLE 1 Coatings in the method according to the invention: Content of Coating Coating Drying drying agent thickness Barrier Name material agent (wt. %) [m] layer V1 B1 G1 10 100 V2 B2 G1 50 100 V3 B3 G1 10 100 V4 B4 G1 10 100 V5 B1 G2 10 100 V6 B2 G2 50 100 V7 B3 G2 10 100 V8 B4 G2 10 100 V9 B2 G2 10 100 T1 C1 B2 0 100

[0113] With the drying agent contents shown, all of the coating materials 20 showed a viscosity according to DIN 53019-1 at a measuring temperature of 23 C. and a shear rate of 1 s.sup.1 in use of a standard cylinder geometry of below 10,000 mPa.Math.s.

[0114] After drying of the coating, the minimum bending radius R is determined immediately after production.

[0115] Intermediate storage of the coatings on thin sheet glass films V1-V8 and the comparison sample C1 is carried out immediately after their production for 2 hours at 40 C. and 90% relative humidity with a bending radius R of 100 mm, with the thin sheet glass film 10 located on the inner side of the radius R, so that the side of the thin sheet glass film 10 which is subjected to the greatest tensile stress is covered with the coating of the coating material 20 containing a drying agent. This simulates the time between the production of a wound-up composite and the packing of the roll.

[0116] After this, the composite is stored in a permeation-tight package (welded into a aluminum composite film) at 60 C. for another 60 days with a bending radius R of 100 mm, with the thin sheet glass film 10 again lying on the inner side of the radius R. The minimum bending radius R is then determined. Determination of the water content is also carried out after this storage period of 60 days.

[0117] For sample V9, intermediate storage of the coating on the thin sheet glass film is carried out immediately after it is produced for 14 days at 40 C. and 90% relative humidity with a bending radius R of 100 mm, with the thin sheet glass film 10 lying on the inner side of the radius R. This simulates a longer time between the production of a wound-up composite and the packing of the roll. The further procedure is the same as for the other samples.

[0118] Moreover, the reversibility of coating of the thin sheet glass film 10 is subjectively assessed by means of manual peel-off experiments. For this purpose, the composite is glued with its glass side by means of strongly adhesive tape (tesa 4972) to a steel plate, the coating is pulled up beginning from the corner using a gripper attached using the same adhesive tape.

TABLE-US-00009 TABLE 2 Results of the method Water Bending Bending content of radius radius polymer Reversibility without after coating + detachable as a layer storage storage Example [ppm] nondetachable [mm] [mm] V1 15 28 32 V2 26 31 38 V3 11 + 32 31 V4 9 30 31 V5 11 28 33 V6 114 33 40 V7 8 + 32 34 V8 9 29 30 V9 18 31 30 C1 1320 28 45

[0119] The results show that with the method according to the invention, the thin sheet glass film 10 can be outstandingly protected. On the average, the coated thin sheet glass films 10 accordingly to the invention show virtually no increase in the minimum bending radius R, while the comparison example shows a significant increase.

[0120] In this case, the permeation-inhibiting additional barrier layer 30 (V9) is particularly suitable, as it considerably reduces the diffusion of humidity into the composite 31, and therefore has a lower minimum bending radius R than the corresponding sample without the permeation-inhibiting additional layer 30 (V6) despite the longer storage time and lower content of getter material. The use of the strongly permeation-inhibiting coating material 20 (B3 and B4) also provides advantages compared to the more permeable coating material 20.

[0121] The water content of the coating materials 20 after storage is determined according to DIN 53715 (Karl Fischer titration). The measurement takes place in a Karl Fischer Coulometer 851 in combination with an oven sampler (oven temperature 140 C.). With a starting weight of approx. 0.5 g of the composite, threefold determination is carried out in each case, with the water content relating in each case only to the amount of the coating material, as it is assumed that the glass itself does not absorb any relevant amount of water. The arithmetic mean of the measurements is given as the water content.

[0122] It is found that the getter material in the coating material significantly reduces the amount of water to which the glass is exposed, and that this has a clear effect on the minimum bending radius.

[0123] The determination of the minimum bending radius R takes place by means of the two point bending test. The test method is based on the Corning method published by S.T. Gulati and the Patent WO 2011/084323 A1 (Gulati et al., ID Symposium Digest of Technical Papers, Vol. 42, Issue 1, pages 652 to 654, June 2011).

[0124] In order to eliminate edge effects, a stabilized strip approx. 10 mm wide of the adhesive tape tesa 50575 (80 m thick aluminium film with an acrylate pressure-sensitive adhesive) is applied along both edges of the thin sheet glass film transversely to the bending axis so that it protrudes approx. 1 mm over the glass edge. These aluminium strips come to rest during the bending test on the outer side of the bending radius and cause the glass edge to be kept under compressive stress, thus sharply reducing the risk of cracks originating there.

[0125] The flexibility of the coated glass can be characterized by the two point bending test. In this case, the minimum bending radius R is measured and calculated in mm shortly before or exactly at the moment of breakage. The laminate has the coating side facing upward and is fixed on one side. The other side is displaced at a rate of 10 mm/min in the direction of the fixed end. The resulting bending radius R is measured or calculated from the elongation. The test structure for the two point bending test is shown in FIG. 3a. A dotted line represents the position and length L of the coated thin sheet glass 31 before bending. The solid line schematically indicates the position of the coated thin sheet glass 31 at the minimum bending at the moment of the first crack occurring transversely to the direction of movement.

[0126] L is the length of the coated thin sheet glass 31, and s is the distance the one end of the coated thin sheet glass 31 has traveled during the bending process until breakage. The thickness of the coated thin sheet glass is indicated by d, and is the contact angle required for calculating the bending stress . As the contact angle decreases, i.e. as the radius R decreases, the stress on the glass increases.

[0127] The experiment is recorded in a side view using a videocamera. The radius R is measured at the moment of breakage using the device shown in the figure or calculated using the formula below. The bending elongation required for calculating the bending radius R is calculated using a strain gauge.

[0128] FIG. 3b shows the arrangement of the strain gauge in the center of the thin sheet glass composite 31.

[0129] The bending radius R is calculated from the measured bending elongation as follows:

[00001]$\frac{R}{R+\frac{d}{2}}=\frac{L}{L+.Math..Math.L}$$\frac{R}{R+\frac{d}{2}}=\frac{1}{1+\frac{.Math..Math.L}{L}}=\frac{1}{1+\mathrm{.Math.}}$$R+R.Math..Math.\mathrm{.Math.}=R+\frac{d}{2}$$R=\frac{d}{2.Math..Math.\mathrm{.Math.}}$

[0130] With the bending elongation =L/L, L: original length and length of the medium phase of the thin sheet glass composite 31 with radius R, and L corresponds to the change in length of the outer phase of the thin sheet glass composite 31 with radius R+d/2 in FIG. 3c.

[0131] As the minimum bending radius R of Table 2, the median value of 15 measurements is given.

Measurement Methods

Molecular Weight

[0132] The molecular weight determinations of the number average molecular weights M.sub.n and the weight average molecular weights M.sub.w (or the other molecular weights) were carried out by means of gel permeation chromatography (GPC). THF (tetrahydrofuran) with 0.1 vol.-% of trifluoroacetic acid was used as an eluent. Measurement was carried out at 25 C. The PSS-SDV, 5, 10.sup.3 , ID of 8.0 mm50 mm, was used as a precolumn. The columns PSS-SDV, 5, 10.sup.3, 10.sup.5, and 10.sup.6 with ID of 8.0 mm300 mm respectively were used for separation. The sample concentration was 4 g/l, the flow rate was 1.0 ml per minute. Measurement was conducted against polystyrene standards.

LIST OF REFERENCE NUMBERS

[0133] 10 Thin sheet glass film [0134] 20 Polymeric coating material [0135] 30 Additional barrier layer [0136] 31 Thin sheet glass composite [0137] d Thickness of the thin sheet glass composite [0138] l Drying agent [0139] s Displacement of the thin sheet glass composite [0140] L Length of the thin sheet glass composite [0141] R Radius/bending radius [0142] Contact angle [0143] Bending stress [0144] Bending elongation