Liner for protection of adhesives

Abstract

In the case of a liner for the protection of adhesives, the protective effect is to be enhanced in respect of permeates originating from the environment and also permeates included during winding or stacking and other processing steps. This enhancement is accomplished through provision of a liner which comprises at least one adhesive release layer and at least one layer of a getter material capable of sorbing at least one permeable substance.

Claims

1. A release liner for the protection of adhesive, the release liner comprising a first layer contacting a second layer, wherein the first layer of the release liner is an adhesive release layer and the second layer of the release liner is a layer of a getter material capable of sorbing at least one permeable substance, wherein the getter material is selected from the group consisting of calcium oxide, boron trioxide, sodium sulfate, potassium carbonate, copper sulfate, magnesium perchlorate, magnesium sulfate, zeolites and mixtures thereof.

2. The release liner according to claim 1, wherein the release liner comprises at least one third layer that is a carrier layer.

3. The release liner according to claim 1, wherein the release liner comprises a barrier layer against one or more specific permeates.

4. The release liner according to claim 1, wherein the getter material binds a permeate by chemisorption.

5. The release liner according to claim 1, wherein the layer of getter material is porous and/or foamed.

6. The release liner according to claim 1, wherein the release liner consists of a third layer that is a carrier layer, the adhesive release layer and the layer of the getter material capable of sorbing at least one permeable substance.

7. An adhesive covered at least on one side and at least partially with the release liner according to claim 1.

8. The adhesive according to claim 7, wherein the adhesive before being contacted with the release liner has a permeate content of less than 1000 ppm.

9. A method comprising: providing an adhesive tape that is at least partially covered on at least one side with a release liner comprising (i) at least one adhesive release layer and (ii) at least one layer of a getter material capable of sorbing at least one permeable substance, wherein the getter material is selected from the group consisting of calcium oxide, boron trioxide, sodium sulfate, potassium carbonate, copper sulfate, magnesium perchlorate, magnesium sulfate, zeolites and mixtures thereof; and encapsulating optoelectronic arrangements with the adhesive tape.

Description

DRAWINGS

(1) 10: Carrier layer

(2) 11: Release layer

(3) 20-25: Layer of getter material

(4) FIG. 1 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a continuous layer of getter material (20) in between.

(5) FIG. 2 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a perforated layer of getter material (21) in between.

(6) FIG. 3 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a perforated layer of getter material (22) in between, where the layer of getter material penetrates at least partly into the surface of the release layer and of the carrier layer.

(7) FIG. 4 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a layer of particulate getter material (23) in between.

(8) FIG. 5 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a layer of particulate getter material (23) in between, where the layer of getter material penetrates at least partly into the surface of the release layer and of the carrier layer.

(9) FIG. 6 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a layer of particulate getter material (24) in between, in which the getter material is embedded in a matrix material and comprises more than 50% by weight of the getter material layer.

(10) FIG. 7 shows a liner of the invention consisting of a release layer (11) and a carrier layer (10) and also a layer of particulate getter material (25) in between, in which the getter material is embedded loosely in a sheetlike textile structure material and comprises more than 50% by weight of the getter material layer.

EXAMPLES

(11) Various liners provided with a getter material layer were produced. They were laminated to various adhesive tapes by means of a laboratory roll laminator in a controlled-climate chamber at 23 C. and a relative atmospheric humidity of 50%.

(12) Adhesive Tapes

(13) To produce adhesive tapes, different pressure-sensitive adhesives (PSAs) were applied, using a laboratory coating instrument, from a solution to a conventional liner which is not in accordance with the invention and is not impervious to permeation, this liner being of the type ALU I 38 UV1 from Mondi, comprising an aluminium foil carrier, and dried. The layer thickness of the adhesive after drying was 25 m in each case. Drying took place in each case at 120 C. for 30 minutes in a laboratory drying cabinet.

(14) K1: Pressure-Sensitive Adhesive

(15) TABLE-US-00001 100 parts Tuftec P 1500 SBBS with 30% by weight block polystyrene content from Asahi. The SBBS contains about 68% by weight diblock content. 100 parts Escorez 5600 hydrogenated HC resin with a softening point of 100 C., from Exxon 25 parts Ondina 917 white oil comprising paraffinic and naphthenic fractions, from Shell

(16) The solvent used was a 2:1 mixture of toluene and acetone.

(17) K2: Hotmelt Adhesive

(18) TABLE-US-00002 100 parts Kraton FG 1924 maleic anhydride-modified SEBS with 13% by weight block polystyrene content, 36% by weight diblock and 1% by weight maleic acid, from Kraton 25 parts Escorez 5600 hydrogenated HC resin (hydrocarbon resin) having a softening point of 100 C., from Exxon .sup.1 part aluminium acetylacetonate

(19) The solvent used was a 2:1 mixture of toluene and acetone.

(20) K3: Radiation-Activatable Hotmelt Adhesive

(21) TABLE-US-00003 25 parts Epiclon 835 LV bisphenol A and bisphenol F based epoxy resin from DIC, Japan, molecular weight M.sub.w about 350 g/mol 25 parts Epicote 1001 bisphenol based epoxy resin from Mitsubishi Chemical Company, Japan, molecular weight M.sub.w about 900 g/mol 50 parts YP-70 bisphenol A and bisphenol F based phenoxy resin from Nippon Steel Chemical Group, Japan, molecular weight M.sub.w about 55 000 g/mol 1.5 parts Irgacure 250 iodonium salt-based UV photoinitiator from BASF (iodonium, (4-methylphenyl) [4-(2-methylpropyl) phenyl]-, hexafluorophosphate(1-))

(22) The solvent used was methyl ethyl ketone.

(23) K4: Heat-Activatable Adhesive

(24) TABLE-US-00004 90 parts Ultramid 1C copolyamide 6/66/136 from BASF, having a viscosity number of 122 ml/g in 96% strength sulphuric acid in accordance with ISO 307 10 parts EPR 166 bisphenol based epoxy resin from Bakelite, epoxide number of 184 20 parts PEG 2000 polyethylene glycol with an average molar mass of 2000 20 parts Foralyn 5040 tackifier resin from Eastman

(25) The adhesive was prepared in a process as disclosed in DE102006047739 A1, using ethanol as solvent.

(26) The layers of adhesive were stored for 72 hours at 23 C. and 50% relative atmospheric humidity (atmosphere A). The water content of the layers of adhesive was determined in each case before combination with the liner.

(27) Measurement of the Water Content

(28) The water content was determined in accordance with DIN 53715 (Karl-Fischer titration). Measurement took place on a Karl-Fischer Coulometer 851 in conjunction with an oven sampler (oven temperature 140 C.). A triple determination was carried out with an initial mass each time of around 0.3 g. The water content reported is the arithmetic mean of the measurements.

(29) TABLE-US-00005 Water content [ppm] Layer of adhesive atmos. A K1 853 K2 551 K3 3216 K4 16400

(30) Liner

(31) Carrier Materials:

(32) Carrier materials used for the liner were in one case a polyester carrier approximately 75 m thick (Lumirror 60.01/75 from Toray Plastics, hereinafter: PET) and also a polyester film approximately 30 m thick with an inorganic barrier layer coating (GX-P-F from Toppan Printing, hereinafter: barrier-PET).

(33) Also prepared was a polyolefin-based film (PO), by flat-film coextrusion. This film consisted of a 50 m base layer and a 10 m outer layer. The base layer consisted of 91.3% (w/w) of polypropylene block copolymer Novolen 2309 L (BASF, melt index 6 g/10 min at 230 C. and 2.16 kg, ethylene content about 6.5% (w/w)), 8.4% (w/w) of titanium dioxide and 0.3% (w/w) of the HALS stabilizer Tinuvin 770.

(34) The outer layer consisted of 85% of ethylene-multiblock copolymer Infuse D9107 (The Dow Chemical Company, d=0.866 g/cm3) and 15% of polyethylene LD251 (ExxonMobil, d=0.9155). The outer layer material and also the base layer was conveyed into the feed block of the coextrusion unit, with extrusion on an extrusion line from Dr. Collin.

(35) Release Layers:

(36) The outer layer of the abovementioned polyolefin film was also used as release layer (PO).

(37) In the case of the silicone system used, the system in question is an addition-crosslinking silicone system from Wacker. 9.75 g of DEH 915 (a polydimethylsiloxane functionalized with vinyl groups) were mixed with 0.33 g of V24 (a methylhydrogenpolysiloxane) and 0.08 g of Kat OL (a platinum catalyst, also known under the name Karstedt catalyst). Beforehand, both raw materials had been dried by means of zeolite beads (Molecular Sieves 4 A from the supplier Sigma-Aldrich) at 23 C.

(38) The release system was coated onto the carrier materials with a getter material layer, with the aforementioned release system formulation being applied via a laboratory coating unit. The coating weight was 2 g/m.sup.2. After coating, the release systems were crosslinked in a forced-air oven at 160 C. for 30 seconds.

(39) Getter Materials Used:

(40) TABLE-US-00006 Identification Description Trade Name Supplier G1 calcium oxide calcium oxide Sigma-Aldrich nanopowder G2 lithium chloride lithium chloride Sigma-Aldrich anhydrous G3 calcium high-purity Osnabruegge calcium granules G4 zeolite 3A Purmol 3 STH Zeochem

(41) For application in thin layers, getter materials G2 and G4 were ground and screened where necessary so that there were no particles present which were larger than the layer thickness. After the grinding operation, these particles were regenerated by heat treatment in a manner known to the skilled person.

(42) Production of the Liners:

(43) The liners were produced in a glovebox under a nitrogen atmosphere at 23 C. at 1 ppm water content.

(44) Liners with the pulverulent getter materials G1, G2 and G4 were produced by scattering an amount of approximately 2 g/m.sup.2 onto the outer layer side of the polyolefin-based carrier film, using a sieve.

(45) Then a second polyolefin-based carrier film was laminated by the base layer side onto the getter material layer by means of a heating press at 160 C.

(46) Alternatively the getter material was consolidated in the outer layer by means of a laboratory laminating instrument with silicone rolls at a roll temperature of 160 C. A layer of the silicone release system was then applied as described above onto the getter material layer.

(47) For adhesive tapes with calcium as the getter material, the metal was applied by vapour deposition under reduced pressure onto the PET film and onto the PET barrier film (in that case on the side bearing the inorganic barrier layer), producing in each case a getter material layer thickness of around 300 nm. Then a layer of the silicone release system was applied as described above onto the getter material layer.

(48) Table 1 shows an overview of the liners produced which comprise layers of getter material:

(49) TABLE-US-00007 TABLE 1 Getter material-filled liners Getter Carrier Getter material amount Identification material layer [g/m.sup.2] Release layer L1 PET G3 0.47 Silicone L2 Barrier PET G3 0.47 Silicone L3 PO G1 1 Silicone L4 PO G2 1 Silicone L5 PO G4 1 Silicone L6 PO G1 1 PO L7 PO G2 1 PO L8 PO G4 1 PO L9 PET 0 Silicone (comparative example)

(50) For further investigation, adhesive tape sections measuring approximately 100100 mm.sup.2 were conditioned as already described above and immediately thereafter were lined with the liner at 23 C. and 50% relative atmospheric humidity, using a laboratory laminator with a roll temperature of 80 C. The laminates produced in this way were stored under the following atmospheres for 168 hours:

(51) Atmosphere B: 23 C., sealed in vacuumized packaging impervious to permeation

(52) Atmosphere C: 23 C., 95% relative atmospheric humidity

(53) Lastly, the water content of the adhesive was determined in the specimens. Here, samples were taken from the centre of the area of the specimen, in order to avoid margin effects. The results are summarized in Table 2:

(54) TABLE-US-00008 TABLE 2 Determination of the water content Water content of adhesives Assembly [ppm] storage after after Liner Adhesive atmosphere conditioning storage Example 1 L1 K1 atmos. B 853 309 2 L2 K1 atmos. B 853 285 3 L3 K1 atmos. B 853 212 4 L4 K1 atmos. B 853 125 5 L5 K1 atmos. B 853 388 6 L6 K1 atmos. B 853 259 7 L7 K1 atmos. B 853 186 8 L8 K1 atmos. B 853 518 9 L1 K1 atmos. C 853 1180 10 L2 K1 atmos. C 853 491 11 L3 K1 atmos. C 853 1220 12 L4 K1 atmos. C 853 852 13 L5 K1 atmos. C 853 1160 14 L6 K1 atmos. C 853 1190 15 L7 K1 atmos. C 853 817 16 L8 K1 atmos. C 853 1290 17 L1 K2 atmos. B 551 208 18 L2 K2 atmos. B 551 133 19 L3 K2 atmos. B 551 95 20 L6 K2 atmos. B 551 136 21 L1 K2 atmos. C 551 803 22 L2 K2 atmos. C 551 263 23 L3 K2 atmos. C 551 806 24 L6 K2 atmos. C 551 785 25 L1 K3 atmos. B 3216 593 26 L2 K3 atmos. B 3216 459 27 L3 K3 atmos. B 3216 310 28 L6 K3 atmos. B 3216 382 29 L1 K3 atmos. C 3216 5200 30 L2 K3 atmos. C 3216 641 31 L3 K3 atmos. C 3216 4650 32 L6 K3 atmos. C 3216 4650 33 L1 K4 atmos. B 16400 3390 34 L2 K4 atmos. B 16400 2650 35 L3 K4 atmos. B 16400 1770 36 L6 K4 atmos. B 16400 1690 37 L1 K4 atmos. C 16400 34440 38 L2 K4 atmos. C 16400 5310 39 L3 K4 atmos. C 16400 31490 40 L6 K4 atmos. C 16400 34800 Comparative examples C1 L9 K1 atmos. B 853 965 C2 L9 K2 atmos. B 551 657 C3 L9 K3 atmos. B 3216 3840 C4 L9 K4 atmos. B 16400 16940 C5 L9 K1 atmos. C 853 1337 C6 L9 K2 atmos. C 551 894 C7 L9 K3 atmos. C 3216 6882 C8 L9 K4 atmos. C 16400 38700

(55) The results show that liners of the invention are suitable for keeping permeates away from adhesive tapes or for limiting the amount of permeate that penetrates (Examples 9-16, 21-24, 29-32 and 37-40 in comparison to the Comparative Examples C5-C8).

(56) It is particularly advantageous for the liner to comprise a barrier layer against one or more permeates or for the carrier material itself to exhibit a strong barrier effect against the permeate (L2), since then the getter capacity is sufficient not only to scavenge the entire amount of the permeate to which it is exposed, but also, furthermore, to reduce the amount of permeate already present in the adhesive (Examples 10, 22, 30, 38).

(57) The surprisingly good suitability of the liners of the invention for removing permeates from adhesive tapes is also shown by Examples 1-8, 17-20, 25-28 and 33-36.