CN112424970A

CN112424970A - Combination of transparent full-area package and (non-transparent) edge package with high getter content

Info

Publication number: CN112424970A
Application number: CN201980034581.1A
Authority: CN
Inventors: J.龙普夫; B.韦德尔; K.凯特-特尔根布谢尔; T.克拉温克尔
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2018-05-24
Filing date: 2019-04-26
Publication date: 2021-02-26
Also published as: DE102018208168A1; WO2019223953A1; EP3803997A1

Abstract

An organic electronic structure comprising a substrate, an organic electronic device arranged on the substrate, a cover at least partially covering the organic electronic device and at least partially regionally affixed to the substrate and/or the electronic device, wherein the structure further comprises: at least one layer of a first adhesive at least partially covering the organic electronic device and having a transparency greater than 80% and a haze less than 5%; and at least one layer of a second adhesive surrounding the at least one layer of the first adhesive on a perimeter of the at least one layer of the first adhesive such that the at least one layer of the second adhesive forms an edge seal, wherein the width of the edge seal using the second adhesive is no more than 2mm, and wherein the second adhesive has a water absorption capacity greater than 5 wt%. This design allows the width of the edge region around the display or other organic electronic structure to be small.

Description

Combination of transparent full-area package and (non-transparent) edge package with high getter content

The invention relates to a protection method for protecting an organic electronic device arranged on a substrate, comprising the steps of: applying a cover over the organic electronic device in a manner that at least partially covers the organic electronic device, and affixing the cover with at least one layer of a first adhesive and at least one layer of a second adhesive. The invention also relates to an organic electronic structure comprising a substrate, an organic electronic device arranged on the substrate and a layer covering at least partially the organic electronic device and at least partially regionally (partially areal,

) A cover affixed to the substrate and/or the organic electronic device.

(opto) electronic devices are increasingly used in commercial products. Such devices include organic or inorganic electronic structures such as organic, organometallic, or polymeric semiconductors and combinations thereof. Depending on the desired application, these devices and products can be designed to be rigid or flexible, with an increased demand for flexible devices. The production of such devices is carried out, for example, by means of printing processes such as letterpress printing, intaglio printing, screen printing, offset printing or so-called "non-impact printing" such as thermal transfer printing, inkjet printing or digital printing. However, in many cases, vacuum processes such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), plasma-enhanced chemical or physical deposition (PECVD), sputtering, (plasma) etching or evaporation are also used, wherein structuring is usually performed using masks.

Examples of (opto) electronic applications which are already commercially available or have great market potential are here exemplified electrophoretic or electrochromic structures or displays, organic or polymer light-emitting diodes (OLEDs or PLEDs) in advertising and display devices or as illumination, electroluminescent lamps, light-emitting electrochemical cells (LEECs), organic solar cells, preferably dye or polymer solar cells, inorganic solar cells, preferably thin-layer solar cells, in particular those based on silicon, germanium, copper, indium or selenium, organic field-effect transistors, organic switching elements, organic optical amplifiers, organic laser diodes, organic or inorganic sensors or RFID transponders based on organic or inorganic.

In the present description, an organic (opto) electronic device is therefore understood to mean an electronic device which comprises at least one at least partially organic component having an electronic function, for example an organometallic compound.

In the field of inorganic and/or organic (opto) electronics, but in particular in the field of organic (opto) electronics, a technical challenge to achieving a sufficient lifetime and functionality of (opto) electronic devices is to protect the components contained therein from permeants. The permeate can be various low molecular organic or inorganic compounds, in particular water vapour and oxygen.

In the field of inorganic and/or organic (photo) electronics, more particularly in the case of the use of organic raw materials, many (photo) electronic devices are sensitive to both water vapor and oxygen, wherein for many devices the penetration of water or water vapor is considered to be a major problem. Thus, during the lifetime of the electronic device, protection by means of the encapsulation is required, since otherwise the performance will degrade during the lifetime. For example, oxidation of components can lead to a significant reduction in brightness in a very short time for light-emitting devices such as electroluminescent lamps (EL lamps) or organic light-emitting diodes (OLEDs), a significant reduction in contrast for electrophoretic displays (EP displays) or a significant reduction in efficiency for solar cells.

Proof of factThe full-area (full-area,

) An encapsulation, the adhesive or tape completely covering the organic electronic structure applied on the substrate and the edge region and connecting this region with the impermeable cover. In the case of light-emitting or light-consuming structures, the adhesive layer must be highly transparent and have little light scattering (haze).

In order to achieve a long service life of the structure, it is advantageous to equip the adhesive with a collector material, for example a desiccant, in order to achieve a barrier effect against penetrating permeants.

In order to characterize the barrier effect, the oxygen Transmission rate OTR (oxygen Transmission rate) and the water Vapor Transmission rate WVTR (Water Vapor Transmission rate) are generally specified. In this case, the respective ratio represents the flow rate of oxygen or water vapour through the membrane in relation to the area and time under specific temperature and partial pressure conditions and optionally other measurement conditions (e.g. relative humidity). The lower these values, the better the corresponding material is suitable for encapsulation. Here, the indicator of penetration is not only based on the value of WVTR or OTR, but always also includes an indicator of the average path length of penetration, such as the thickness of the material, or the standardization of a particular path length.

The permeability P is a measure of the permeability of the object to gases and/or liquids. A low P value characterizes a good blocking effect. Permeability P is a specific value for a defined material and a defined permeate at a specific permeate path length, partial pressure and temperature under steady state conditions. Permeability P is the product of the diffusion term D and the solubility term S: p ═ D · S.

The solubility term S primarily describes the affinity of the barrier adhesive composition for the permeant. For example, in the case of water vapor, a low S value is achieved for hydrophobic materials. The diffusion term D is a measure of the mobility of the permeant in the barrier material and is directly dependent on properties such as molecular mobility or free volume. Relatively low D values are often achieved for strongly crosslinked or highly crystalline materials. However, in general, highly crystalline materials are less transparent and stronger cross-linking results in lower flexibility. The permeability P often increases with increasing molecular mobility, for example even at elevated temperatures or above the glass transition temperature.

The method of increasing the barrier effect of the adhesive composition must take into account these two parameters D and S, in particular, with regard to the influence on the permeability to water vapor and oxygen. In addition to these chemical properties, the effect of the physical influence on the permeability must also be taken into account, in particular the mean permeation path length and the interfacial properties (flow behavior, adhesion of the adhesive composition). The ideal barrier adhesive composition has a low D and S value and very good adhesion to the substrate.

The low solubility term S alone is generally not sufficient to achieve good barrier properties. In particular, a typical example thereof is a silicone elastomer. This material is extremely hydrophobic (small solubility term) but has a relatively low barrier effect against water vapor and oxygen due to its freely rotatable Si-O bond (large diffusion term). A good balance between the solubility term S and the diffusion term D is also necessary for a good barrier effect.

However, if a highly efficient particulate desiccant such as calcium oxide or zeolite is used to achieve good barrier properties, this can result in increased haze, which, as noted above, can be problematic for light emitting or consuming structures. Due to the high refractive index of these desiccants (calcium oxide: 1.86), the haze is already significantly greater than 5% at a proportion of 2% by weight for conventional package adhesive compositions. Transparent and antifog desiccants such as silanes are known but are less effective.

As an alternative to full area encapsulation, edge encapsulation may therefore also be employed to maintain transparency in the relevant areas of the structure, with only the area surrounding the electronic structure being provided with the encapsulating adhesive composition. Since special optical requirements do not need to be met in the edge region, a high filling with efficient desiccants is possible. The disadvantage here is the remaining cavity in the encapsulated structure. Therefore, arrangements are also known in which edge encapsulation and full-area encapsulation are combined.

Edge encapsulation with a sealant is known, for example, from WO 2009085736. This patent discloses a solar panel that is covered over the entire area by a desiccant-free adhesive layer and is encapsulated at the edges by a desiccant-containing encapsulant. The sealing material is applied from the melt in liquid form.

US 2008/0289681 a1 discloses a solar cell module in which the solar cells are applied to a substrate by casting a layer of the composition. The solar cell is covered by a transparent cover layer by means of a further layer of the casting composition. The module may also have an edge package containing desiccant that is 5-20mm wide. Zeolites are used as desiccants. Preferred embodiments of the edge package are hot melt films and hot melt pastes.

US 6,936,131B 2 describes the use of desiccant filled transfer tape that can be used as a full area package or an edge package. Inorganic particles are described as desiccants. The particles used in the examples result in high haze of the adhesive composition.

US20070013292a1 discloses an organic electronic structure provided with an edge package containing a desiccant. The edge seal can be designed as a curable adhesive or as an adhesive tape. The width of the edge encapsulation is preferably designed to be larger than 2 mm.

In the field of mobile electronic devices, a trend is observed to narrow the edges around the display. The width of the web (Stegbreite) of the bonding zone outside the active zone is generally not more than 2 mm. The performance limit of highly transparent encapsulating adhesives with little light scattering is reached in such devices, and the service life is no longer satisfactory, since the short distance from the environment to the active area is traversed by penetrating permeants, in particular water vapor, in too short a time, and then leads to destruction. This Time period is called Lag-Time.

Furthermore, a difficulty with these smaller web widths is tolerances in the application: the desiccant containing edge encapsulation arranged outside the active face, i.e. the active area, must not in any case project into the active face or flow into it during use. For reasons of tolerance, the entire, inherently small web width cannot therefore be used for efficient edge sealing.

It is therefore an object of the present invention to provide an improved encapsulation of narrow-sided organic electronic structures which enables an improved utilization of the narrow sides for permeation barriers, thus better protecting the encapsulated object from permeation of moisture, while at the same time not causing impairment of the optical properties of the organic electronic structure.

This object is achieved with a protection method of the type mentioned at the outset in that: at least one layer of a first adhesive at least partially covers the organic electronic device and has a transparency of greater than 80% and a haze of less than 5%, and at least one layer of a second adhesive surrounds the at least one layer of the first adhesive on a perimeter of the at least one layer of the first adhesive, such that the at least one layer of the second adhesive forms an edge seal, wherein the width of the edge seal using (with) the second adhesive does not exceed 2mm (i.e., 2mm or less), and wherein the second adhesive has a water absorption capacity, i.e., water absorption capacity, of greater than 5 wt.%

Furthermore, according to the present invention there is provided an organic electronic structure of the above-mentioned type, wherein the structure further has at least one layer of a first adhesive and at least one layer of a second adhesive, the first adhesive at least partially covering the organic electronic device and having a transparency of more than 80% and a haze of less than 5%, the at least one layer of the second adhesive surrounding the at least one layer of the first adhesive on the periphery of the at least one layer of the first adhesive, whereby the at least one layer of the second adhesive forms an edge seal, wherein the width of the edge seal using (with) the second adhesive does not exceed 2mm and it has a water absorption capacity of more than 5% by weight.

Thereby combining a first transparent full-area encapsulation with a second (non-transparent) edge encapsulation with high water absorption capacity.

Preferred embodiments of the method and of the organic electronic structure are contained in the dependent claims. Preferred embodiments of the method apply analogously to organic electronic structures and vice versa.

The organic electronic component is preferably designed such that no further polymer layer is present between the cover and the organic electronic device, i.e. only at least one layer of the first adhesive, in particular only one layer of the first adhesive, is present as a polymer layer, and no further layer is present.

Polymers are compounds which are generally composed of organic chains or branched molecules (macromolecules), which are composed of identical, similar or different units (so-called monomers). In the simplest case, the macromolecule consists of only one type of monomer. Copolymers are composed of various monomers which are randomly distributed in the macromolecule, regularly distributed or can exist in block form. The polymer comprises at least three identical monomer units. A monomeric unit within the meaning of this definition is the bound form of the monomer in the polymer.

Structures in which the organic electronic device is located directly on the substrate are also particularly advantageous.

Likewise, structures in which the organic electronic device arranged on the substrate is already provided with a primary encapsulation, for example a thin-film encapsulation, and the method claimed here is carried out as a secondary encapsulation on one or both sides of the electronic device arranged on the substrate are particularly advantageous.

The cover at least partially covers the organic electronic device. It preferably completely covers the organic electronic device.

At least one layer of the first adhesive at least partially covers the organic electronic device. It preferably completely covers the organic electronic device.

Preferred are structures in which the second adhesive does not contact or cover the organic electronic device, i.e. structures in which the second adhesive is applied at a distance from the organic electronic device. The distance of the adhesive application relative to the organic electronic device is preferably 0.1mm to 2mm, in particular 0.2mm to 1mm, particularly preferably 0.2mm to 0.5 mm.

In a preferred embodiment, the distance formed in this way is filled with the first adhesive. If the organic electronic device is surrounded by the primary encapsulation, in a further preferred embodiment the distance is filled with the material of the primary encapsulation. In a further preferred embodiment, the distance is filled by the material of the primary encapsulation and the first adhesive.

The adhesive may be present as a liquid or paste adhesive or in the form of a tape. The use of an adhesive tape is particularly preferred, since it allows a good, i.e. particularly precise and particularly simple, application of the adhesive.

The thickness of the adhesive layer of the first or second adhesive is preferably between about 4 μm and about 250 μm. The thickness of the adhesive is particularly preferably not more than 50 μm, in particular not more than 25 μm.

In principle, any adhesive described in the prior art (e.g. in g.habenicht: Kleben, 6th edition, Springer 2009) can be used as adhesive. Without wishing to unnecessarily limit the invention, examples of such adhesives are based on the following: vinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl chloride, (meth) acrylates, polyamides and copolymers thereof, cellulose, urea, melamine resins, phenolic resins, epoxides, polyurethanes, polyesters, polyaromatics, chloroprene, nitrile rubbers, styrene, butyl rubbers, polysulfides or silicones. Mixtures are also in accordance with the present invention. Preferably an activatable adhesive is used.

The first adhesive is preferably a pressure sensitive adhesive. Particularly preferably, an activatable pressure-sensitive adhesive is used. The first adhesive is more preferably present as a pressure sensitive tape. This simplifies the processing of the adhesive.

Pressure sensitive adhesives are adhesives that allow permanent bonding to a substrate even under relatively weak pressure and that can be peeled off again from the substrate after use with substantially no residue. The pressure-sensitive adhesive functions as a permanent pressure-sensitive adhesive at room temperature, i.e., has a sufficiently low viscosity and high tack to the touch that it can already wet the surface of the corresponding adhesive substrate at low touch pressures. The adherability of the adhesive composition is based on its adhesive properties, while the repeelability is based on its cohesive properties. Various compounds can be used as the basis for pressure sensitive adhesives.

All pressure-sensitive adhesives known to the person skilled in the art can be used as pressure-sensitive adhesives, i.e. based, for example, on: acrylates and/or methacrylates, polyurethanes, natural rubbers, synthetic rubbers, styrenic block copolymer compositions having elastomeric blocks composed of unsaturated or hydrogenated polydiene blocks (polybutadiene, polyisoprene, copolymers of the two, and other elastomeric blocks familiar to those skilled in the art), polyolefins, fluoropolymers, and/or silicones. This also includes other compositions having Pressure-Sensitive Adhesive properties according to the "Handbook of Pressure Sensitive Adhesive Technology" of Donatas Satas (Satas & Associates, Warwick 1999).

Activatable adhesives are considered adhesive systems in which the final bond is produced by input of energy, for example by actinic radiation or heat.

In principle, all conventional adhesive composition systems for activated bonding can be used as activatable adhesive compositions. Activation is usually carried out by energy input, for example by actinic radiation, heat or mechanical energy, such as ultrasound or friction.

Adhesive compositions for heat activated bonding can be divided into two basic categories: thermoplastic heat activated adhesive compositions (hot melt adhesives) and reactive heat activated adhesive compositions (reactive adhesives). This classification also includes those adhesive compositions that can be classified into two categories, namely reactive thermoplastic heat activated bonded adhesive compositions (reactive hot melt adhesives).

Thermoplastic adhesives are based on polymers which reversibly soften when heated and solidify again when cooled. As thermoplastic adhesive compositions, in particular those based on: polyolefins and copolymers of polyolefins and acid-modified derivatives thereof, ionomers, thermoplastic polyurethanes, polyamides and polyesters and copolymers thereof, and block copolymers such as styrene block copolymers.

In contrast, reactive heat activated adhesive adhesives contain reactive components. The latter component is also referred to as "reactive resin", in which the crosslinking process is initiated by heating, which ensures a permanent stable connection after the crosslinking reaction has ended. Such adhesive compositions preferably also contain an elastomeric component, such as a synthetic nitrile rubber or a styrene block copolymer. This elastic component imparts particularly high dimensional stability even under pressure to the heat-activated adhesive composition on account of its high flow viscosity.

The radiation activated adhesive composition is also based on reactive components. The latter component may comprise, for example, polymers or reactive resins, wherein the crosslinking process is initiated by irradiation, which ensures a permanent stable connection after the crosslinking reaction has ended. Such adhesive compositions preferably further comprise an elastomeric component as described above.

Radiation activatable pressure sensitive adhesives differ from radiation crosslinked pressure sensitive adhesives in which the pressure sensitive adhesive properties are set by radiation crosslinking during the production of the adhesive tape. For radiation activatable pressure sensitive adhesives, radiation activation occurs during application. After radiation activation, the adhesive composition generally no longer has pressure sensitive adhesive properties.

Activatable pressure sensitive tapes also include pressure sensitive tapes assembled from two or more adhesive films, such as those disclosed in DE 102013222739 a 1. Two or more adhesive films are activated by contacting them.

Those activatable (pressure-sensitive) adhesive compositions which are prepared from compounds having at least one of the following functional groups are particularly suitable: epoxy groups, amines, urea groups (uretidiophor), hydroxyl groups, ether groups, acid groups, in particular carboxylic acid groups, preferably acrylic and methacrylic acid groups, and also carboxylic anhydride groups, ester groups and amide groups, isocyanates, imidazoles, phenol groups, urea groups (hardstoffgruppen), silane groups, ethylenic double bonds, in particular in combination with initiator groups which can initiate free-radical polymerization, or in combination with sulfur-containing vulcanizing agents.

The activatable (pressure sensitive) adhesive composition may optionally include one or more additional formulation ingredients such as hardeners, reaction promoters, catalysts, initiators, fillers, microspheres, tackifier resins, non-reactive resins, plasticizers, tackifiers, asphalts, age resistors (antioxidants), light protection agents, UV-absorbers, rheological additives, and other adjuvants and additives.

Examples of (barrier) adhesive compositions particularly suitable for use in the present invention can be found in US 2006/0100299 a1, WO 2007/087281 a1, EP 2166593 a1, EP 2279537B 1, EP 2465149B 1, EP 2768919B 1, EP 2768918 a1, EP 2838968 a1, EP 2838968 a1 or WO 2016066435 a1, where this list is purely exemplary and by no means occlusive.

The second adhesive may likewise be a pressure-sensitive adhesive composition and may also be designed as a pressure-sensitive adhesive tape. However, it is particularly preferred to design the second adhesive as a liquid adhesive.

The second adhesive preferably comprises a desiccant. However, the water absorption properties can also be attributed to the adhesive itself. By way of example, mention is made here of epoxides which have not yet been completely reacted.

In principle, all desiccants familiar to the person skilled in the art can be used as desiccants in the second adhesive. If desiccants are also used in the first adhesive, these are preferably those which do not impair or only slightly impair the transparency of the adhesive.

The water vapor penetrating into the (opto) electronic device is then chemically or physically, preferably chemically, bound to these substances and thereby increases the penetration time ("lag time"). Desiccants are referred to in the literature as "getters", "scavengers", "desiccants" or "absorbents". In the following only the expression "desiccant" is used. The incorporation of the permeated water is either carried out physically by adsorption, typically onto silica, molecular sieves, zeolites or sodium sulfate. Chemically, for example via alkoxysilanes,

Oxazolidine, isocyanate,Barium oxide, phosphorus pentoxide, alkali and alkaline earth metal oxides (e.g. calcium oxide), calcium metal or metal hydrides to bind water (WO 2004/009720 a 2). However, many fillers are not suitable for transparent bonding of, for example, displays with the first adhesive composition because the transparency, particularly the haze, of the adhesive composition is reduced.

In adhesives, it is described that such desiccants are mainly inorganic fillers, such as calcium chloride or various oxides (see US 5,304,419A, EP 2380930 a1 or US 6,936,131 a). Such adhesive compositions predominate in edge encapsulation, i.e. where only the edges are bonded. However, adhesive compositions with such getters are not suitable for full area encapsulation, as they reduce transparency as detailed above.

Organic getters are also described in the adhesive compositions. For example in EP 2597697 a1, wherein a polymeric alkoxysilane is used as desiccant. A number of different silanes are mentioned as desiccants in adhesive compositions in WO 2014/001005 a 1. According to this document, the maximum amount of drying agent to be used is 2% by weight, since the sensitive electronic structures to be encapsulated can be damaged if higher substance ratios are used. The problem is that the organic desiccants used are generally very reactive and lead to damage (so-called "dark spots") when in contact with sensitive organic electronic devices in full-area packages. Thus, adhesive compositions with such desiccants are preferably suitable for edge packaging (second adhesive composition) where there is no direct contact between the adhesive composition and the electronic device.

Desiccants having a water absorption capacity of more than 10% by weight, particularly preferably more than 20% by weight, are preferably used. The proportion of drying agent in the adhesive composition can thereby be kept low, so that the impairment of the technical adhesive properties is reduced.

Calcium oxide is particularly preferred as a drying agent. Which has a high water absorption of more than 20% by weight, absorbs water slowly enough that the drying capacity is largely maintained during the adhesive manufacturing process and binds water without changing its physical form (i.e. without liquefying, for example).

The desiccant content of the second adhesive is preferably 15% by weight or more, particularly preferably 30% by weight or more. In the case of further preferred adhesive compositions having a desiccant content of 40% by weight or more, embodiments in the form of liquid adhesives are preferred, since a high filler content impairs the pressure-sensitive adhesiveness of the adhesive tape.

Very particularly preferably, both embodiments described above are combined. The desiccant content of the adhesive is therefore preferably greater than 20% by weight, the moisture absorption of the desiccant being greater than 10% by weight, particularly preferably greater than 20% by weight.

Particularly preferred are second adhesives comprising a desiccant, which have a water absorption of more than 5% by weight, in particular more than 10% by weight, very particularly more than 14% by weight.

The first adhesive preferably also has water-absorbing properties, preferably comprises a water scavenger, in particular as a fully encapsulated first adhesive

Typically a desiccant.

The first adhesive preferably contains less than 2% by weight of a particulate desiccant, in particular calcium oxide, since in conventional packaging adhesive compositions the haze is usually greater than 5% by weight at a proportion of greater than 2% by weight, due to the high refractive index of many desiccants (calcium oxide: 1.86).

Preferably, the base adhesive composition of the first adhesive and/or the second adhesive, i.e. the adhesive composition formulation without optional addition of a desiccant, has less than 100g/m at 38 ℃/90% relative air humidity²d(g/m²Days) has a Water Vapor Transmission Rate (WVTR), based on a layer thickness of 50 μm, particularly preferably less than 20g/m²d. Preferred are adhesive compositions based on polybutenes, such as butyl rubber, in particular based on modified or unmodified polyisobutenes.

Examples of such adhesive compositions are: WO2013057265 (copolymer of isobutene or butene), DE102008047964a1 (vinyl aromatic block copolymer), US8557084B2 (crosslinked vinyl aromatic block copolymer), EP2200105 (polyolefin), US8460969B2 (butene block copolymer), WO2007087281a1 (hydrogenated cycloolefin polymer with PIB), WO2009148722 (PIB with acrylate reactive resin), EP2502962a1 (PIB-epoxide), JP2015197969 (PIB).

The first adhesive (full area encapsulating adhesive composition) and the second adhesive (edge encapsulating adhesive composition) are preferably based on the same base adhesive composition. This means that the constituents of the adhesive composition which dominate the technical adhesive properties are substantially identical, and it is particularly advantageous if the proportions of the constituents are also substantially identical. In particular, the base polymer or polymers of both adhesive compositions are the same.

In this context, "base adhesive composition", "… -based" or "… -based" means that the properties of the adhesive composition are determined, at least to a large extent, by the basic properties of the base adhesive composition or one or more base polymers or monomers, wherein it is of course not excluded that these are additionally influenced by the use of modification aids or additives or other polymers or monomers in the composition. In particular, this may mean that the proportion of base polymer or base polymers and optionally monomers in the total mass of the polymer phase is greater than 50% by weight.

Among the transparent first adhesives, desiccants are preferred which have a similar refractive index to typical packaging adhesives and thus enable highly transparent adhesive compositions. Similar refractive indices are understood to mean that the difference in refractive index between the first binder and the desiccant is not more than 0.02. Hydrotalcite is particularly preferably used as drying agent. For example, synthetic hydrotalcite (Mg) from Sigma-Aldrich₆Al₂(CO₃)(OH)₁₆·4H₂O, product number 652288) is very suitable.

Especially the full area first adhesive is preferably free of particulate filler as they increase haze.

The transparent first adhesive preferably comprises a molecular-scale dispersed desiccant.

Preferably, the first adhesive is applied as a sheet-like structure (tape) and the second adhesive is applied as a liquid adhesive.

According to the invention, the method further comprises: a first adhesive is first applied as a tape to an electronic device (which is typically disposed on a substrate) or its cover, and then a liquid adhesive is applied as a second adhesive around the electronic device. Finally, the electronic device and the cover are joined, wherein the first adhesive composition acts as a spacer and substantially reduces extrusion of the second adhesive composition.

The width of the edge seal using the second (sealing) adhesive preferably does not exceed 2mm, very particularly preferably less than 1mm, since this maximizes the ratio of the active area of the electronic structure to the total area. Such structures are perceived by users as being particularly visually appealing, for example in the case of a display.

The particular combination of two adhesives according to the invention makes it possible to provide an acceptable lag time for organic electronic structures even with very small edge widths in the range of not more than 2 mm.

Drawings

Fig. 1 shows a calcium test as a measure for determining the service life of an electronic structure. Fig. 2 shows an exemplary curve derived from measured data of a test. Fig. 3 shows exemplary breakthrough times as a function of the water scavenger content. Three embodiments of the organic electronic structure according to the invention, each of which is itself preferred, are shown in figures 4 to 6. Here, fig. 4 shows, in a simple form, an organic electronic structure having an organic electronic device applied on a substrate and a cover applied by two adhesive compositions; FIG. 5 illustrates an organic electronic structure having a primary package and a second cover in addition to the basic components of the structure shown in FIG. 4; and fig. 6 shows an organic electronic structure having a primary encapsulation in addition to the basic components of the structure shown in fig. 4.

Wherein:

1: organic electronic structure

2: substrate

3: organic electronic device

4: covering article

5: first adhesive

6: second adhesive

7: primary packaging, e.g. thin-film packaging

8: a second cover disposed on a face of the structure opposite the first cover.

The organic electronic structure 1 shown in fig. 4 comprises an organic electronic device 3 applied to a substrate 2. The organic electronic device 3 is completely surrounded by the second adhesive 6, to be precise at a distance from the organic electronic device 3. The second adhesive 6 has good water absorption capacity. The organic electronic device 3 is covered by a first adhesive 5. The first adhesive also fills the distance (gap) between the organic electronic device 3 and the second adhesive 6. The layer of first adhesive 5 has a transparency of more than 80% so as not to impair the functionality of the underlying organic electronic device 3.

The organic electronic structure 1 shown in fig. 5 corresponds in its basic structure to the structure shown in fig. 4. Furthermore, it comprises a primary package 7. For example, the primary package may be a thin-film package. The primary encapsulation 7 shown in fig. 5 completely covers the organic electronic device 3 and also fills the gap between the second adhesive 6 and the organic electronic device 3. Finally, the organic electronic structure also has a second cover 8 disposed on the opposite side of the structure to the first cover 4.

The organic electronic structure 1 shown in fig. 6 corresponds in its basic structure to the structure shown in fig. 4. Furthermore, it comprises a primary package 7. For example, the primary package may be a thin-film package. The primary encapsulation 7 shown in fig. 5 completely covers the organic electronic device 3 and fills a partial area of the gap between the second adhesive 6 and the organic electronic device 3. The other partial area of the gap is filled with the first adhesive. A second adhesive is applied to at least a portion of the primary package.

The measuring method comprises the following steps:

unless otherwise stated, measurements were made under test conditions of 23 ± 1 ℃ and 50 ± 5% relative air humidity.

Water vapor permeability (WVTR):

WVTR was measured at 38 ℃ and 90% relative air humidity according to ASTM F-1249-13. In each case two determinations are made and an average is obtained. The values given are normalized to a thickness of 50 μm. For the purposes of the measurements, the adhesive composition, in particular the transfer tape, was adhered to a highly permeable polysulfone membrane (available from Sartorius) which itself did not contribute to the permeation barrier.

Water absorption capacity of adhesive composition:

after storage of the test specimens at 23 ℃ and 50% relative air humidity for 7 days, the test specimens were tested according to DIN EN ISO 62: 2008-05 (gravimetric method, method 4) water absorption was measured. In each case, the pair area is 250cm²And a sample having a thickness of 50 μm were subjected to three repeated measurements. The arithmetic mean of the measurements is expressed as water content in weight%.

Water absorption capacity of the desiccant:

after storage of the test specimens at 23 ℃ and 50% relative air humidity for 7 days, the test specimens were tested according to DIN EN ISO 62: 2008-05 (gravimetric method, method 4) water absorption was measured. In each case, three replicates of about 10g of desiccant were tested. The arithmetic mean of the measurements is expressed as water content in weight%.

Determination of the penetration time (lag time):

the measure used to determine the service life of electronic structures is the calcium test. This is illustrated in fig. 1. For this reason, the typical dimensions will be 10x 10mm²Is deposited on the glass plate 21 and then stored under a nitrogen atmosphere. The thickness of the calcium layer 23 is about 100 nm. For encapsulating the calcium layer 23, a layer (23x 23 mm) with the adhesive composition 22 to be tested was used²) And a thin glass slide 24(35 μm, Schott corporation) as a carrier material. For stabilization, a thin glass slide was laminated with a 100 μm thick PET film 26 by means of a 50 μm thick transfer tape 25 to obtain an optically high transparent acrylate pressure sensitive adhesive composition. Glue is adhered toThe adhesive composition 22 was applied to the slide 21 in such a way that the adhesive composition 22 covered the calcium mirror 23 on all sides (a-a) with a 6.5mm protruding edge.

The size of the calcium mirror was varied to obtain different edge widths. In accordance with the present invention, unless otherwise specified, the adhesive composition layer 22 consists of a transparent first package adhesive composition covering the Ca mirror and a desiccant-filled second package adhesive composition covering the peripheral edge region of width A-A. Due to the opaque slide 24, only penetration through the adhesive or along the interface is measured.

The test is based on the reaction of calcium with water vapor and oxygen, as described, for example, by A.G.Erlat et al in "47th annular Technical Conference Proceedings-Society of Vacuum Coaters",2004, pages 654-659 and by M.E.Gross et al in "46th annular Technical Conference Proceedings-Society of Vacuum Coaters",2003, pages 89-92. Here, the light transmittance of the calcium layer was monitored, which was increased due to the conversion into calcium hydroxide and calcium oxide. In the described test configuration, this was done from the edge, so that the visible area of the calcium mirror was reduced. The time until the absorbance of the calcium mirror was halved was referred to as the lifetime. The method covers both the reduction of the mirror area from the edge and via point decomposition in the region and the uniform reduction of the mirror layer thickness caused by the full-area decomposition.

The measurement conditions selected were 85 ℃ and 85% relative air humidity. Unless otherwise stated, the test specimens were applied in a layer thickness of 25 μm adhesive composition over the entire area and without air bubbles. The decomposition of the calcium mirror was monitored via transmittance measurements. The penetration time (lag time) is defined as the time required for moisture to cover a distance a-a up to the edge of the calcium mirror (see fig. 1). From the observation of the transmittance, the penetration time can be read as the intersection of a straight line passing through the measurement value in the initial stage of the substantial constancy and a straight line passing through the measurement value of the stable slope of the transmittance (═ decrease in absorbance, see fig. 2). The measurement (in hours) is the average of three independent measurements. Fig. 2 shows an exemplary curve derived from measured data of a test.

Molecular weight:

the determination of the molecular weight of the number average molecular weight Mn and of the weight average molecular weight Mw is carried out by means of Gel Permeation Chromatography (GPC). The eluent used was THF (tetrahydrofuran) with 0.1 vol% trifluoroacetic acid. The measurement was carried out at 25 ℃. The pre-column used was PSS-SDV, 5 μ,

ID8.0 mmx 50 mm. For the separation, the column used was PSS-SDV, 5. mu.,

and

and

each having ID8.0mm x 300 mm. The sample concentration is 4 g/l; the flow rate was 1.0 ml/min. The measurements were made against polystyrene standards.

Softening temperature

The measurement of the softening temperature of the gluing resin is carried out by the relative methodology known as the ring & ball method and standardized according to ASTM E28.

The tacky resin softening temperature of the resin was determined using a Herzog HRB754 ring and ball tester. The resin samples were first finely ground. The resulting powder was filled into a brass cylinder having a bottom opening (inner diameter of the upper part of the cylinder 20mm, diameter of the bottom opening of the cylinder 16mm, cylinder height 6mm) and melted on a hot table. The fill volume is selected so that the resin completely fills the cylinder after melting without overflowing.

The resulting sample is placed in a sample holder of HRB754 along with the cylinder. If the softening temperature of the adhesive resin is between 50 ℃ and 150 ℃, the tempering bath is filled with glycerol. Water baths may also be used at lower adhesive resin softening temperatures. The test ball had a diameter of 9.5mm and weighed 3.5 g. The spheres were placed over and on the samples in a tempering bath according to the HRB754 procedure. 25mm below the bottom of the cylinder is the collector plate and 2mm above the bottom of the cylinder is the grating (light barrier). During the measurement process, the temperature was increased at 5 ℃/min. In the temperature range of the softening temperature of the glue resin, the ball starts to move through the bottom opening of the cylinder until it finally rests on the collector plate. In this position, it is detected by the grating and the temperature of the tempering bath is recorded at this point in time. Two measurements were performed. The adhesive resin softening temperature is the average from two separate measurements.

MMAP and DACP

MMAP：

MMAP is the methylcyclohexane-aniline cloud point, which was determined using a modified ASTM D-5773-17e1 method. 5.0g of the test substance (i.e.the adhesive resin sample to be investigated) is weighed into a dry test tube and 10ml of dry aniline (CAS [62-53-3],. gtoreq.99.5%, Sigma-Aldrich #51788 or the like) and 5ml of dry methylcyclohexane (CAS [108-87-2],. gtoreq.99%, Sigma-Aldrich #300306 or the like) are added. Shake the tube until the test substance is completely dissolved. For this purpose, the solution was heated to 100 ℃. The tubes containing the resin solution were then introduced into a Chemotronic Cool cloud point measuring apparatus from Novomatics and heated therein to 110 ℃. Cool at a cooling rate of 1.0K/min. The cloud point is detected optically. For this purpose, the temperature at which the turbidity of the solution is 70% is recorded. Results are reported in ° c. The lower the MMAP value, the higher the aromaticity of the test substance.

DAPC：

DACP is the cloud point of diacetone. 5.0g of the test substance (sample of the adhesive resin to be examined) is weighed into a dry tube and 5.0g of xylene (isomer mixture, CAS [1330-20-7],. gtoreq.98.5%, Sigma-Aldrich #320579 or similar) is added. The test substance was dissolved at 130 ℃ and then cooled to 80 ℃. Any escaped xylenes were made up with additional xylenes so that 5.0g of xylenes were again present. Subsequently, 5.0g diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich # H41544 or the like) was added. Shake the tube until the test substance is completely dissolved. For this purpose, the solution was heated to 100 ℃. The tubes containing the resin solution were then introduced into a Chemotronic Cool cloud point measuring apparatus from Novomatics and heated therein to 110 ℃. Cool at a cooling rate of 1.0K/min. The cloud point is detected optically. For this purpose, the temperature at which the turbidity of the solution is 70% is recorded. Results are reported in ° c. The lower the DACP value, the more polar the test substance.

Transparency:

the clarity (transmission) of the adhesive composition layer was determined according to ASTM D1003-11 (procedure A (Byk Haze-gard Dual Haze Meter), D65 standard illuminant). No correction for interfacial reflection losses was made.

Haze:

the haze value describes the proportion of transmitted light that is forward scattered at a wide angle by the illuminated sample (adhesive composition layer). The haze values thus quantify the structure in the surface or volume that interferes with a clear field of view. The method of measuring haze values is described in ASTM D1003-13. The standard requires that four transmission measurements be taken. Transmittance was calculated for each transmittance measurement. The four transmittances (transmissiongrades) were converted to percent haze values. Haze values were measured with a Haze-gard Dual from Byk-Gardner GmbH.

Refractive index:

the refractive index was determined according to ISO 489 (method A, measuring wavelength 589nm) at 20 ℃ and 50% relative air humidity. Cinnamon oil was used as the contact fluid in the measurement.

For the particles, the refractive index was determined according to ISO 489 (method B, measuring wavelength 589 nm).

Glass transition temperature (T)_g)：

The glass transition point, synonymously referred to as glass transition temperature, is given as the result of measurements by dynamic scanning calorimetry DDK (English: DSC) according to DIN 53765: 1994-03 (especially sections 7.1 and 8.1, however with a uniform heating and cooling rate of 10K/min in all heating and cooling steps (compare DIN 53765: 1994-03; section 7.1; Note 1)). The sample weighed 20 mg.

Example (b):

ingredients used

All quantitative data in the following examples are percentages by weight or parts by weight, unless otherwise indicated. Parts by weight relate here to the entire composition without photoinitiator and without solvent. The amount of photoinitiator is related to the amount of epoxy resin used (expressed as a weight percentage).

SibStar 62M SiBS (polystyrene block-polyisobutylene-block copolymer) from Kaneka having a block polystyrene content of 20 wt.%. M_wThe glass transition temperature of the polystyrene block was 100 ℃ and the polyisobutylene block was-60 ℃ at 60.000 g/mol.

Uvacure 1500: cycloaliphatic diepoxy Compound (3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylic acid) from Cytec having a viscosity of about 300mPas at 23 deg.C

Regalite R1100: completely hydrogenated hydrocarbon resins from Eastman (ring and ball softening temperature 100 ℃, DACP 71 ℃, MMAP 76 ℃)

TerPIB 950: polyisobutenes from TerHell having a weight-average molecular weight of 950g/mol

Triarylsulfonium hexafluoroantimonate: cationic photoinitiators from Sigma-Aldrich. The photoinitiator has an absorption maximum in the range of 320nm to 360nm and is present in the form of a 50% strength by weight solution of propylene carbonate.

Caloxol CP 2: calcium oxide from Omya Chemicals, having a water absorption of about 40% by weight

Hydrotalcit: synthetic hydrotalcite (Mg) from Sigma-Aldrich₆Al₂(CO₃)(OH)₁₆·4H₂O, product No. 652288), a water absorption of about 12% by weight after drying in a convection oven at 200 ℃ for 8 hours

2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane (TEE): triethoxysilane having an alicyclic epoxy group, 19% by weight Water uptake (3 moles of Water per 1 mole of TEE)

Preparation of pressure-sensitive adhesive composition as transparent first adhesive composition

Two formulations for the transparent first pressure sensitive adhesive composition according to the invention are listed in table 1 (the amount of photoinitiator is related to the amount of epoxy resin used; information is given in weight percent with respect to the epoxy resin).

TABLE 1

An activatable encapsulated pressure sensitive adhesive composition (T1) and a desiccant filled pressure sensitive adhesive (T2) were prepared. The refractive index of the encapsulated pressure sensitive adhesive composition T2 without hydrotalcite was determined to be 1.53 and the refractive index of hydrotalcite was determined to be 1.51.

The organic components were dissolved in a mixture of toluene (300 parts), acetone (150 parts), and special boiling point solvent oil 60/95(550 parts) at room temperature to form a 50 wt% solution. The photoinitiator triarylsulfonium hexafluoroantimonate or hydrotalcite is then added to the solution.

The formulation was coated from solution onto a siliconized PET liner as a support layer using a doctor blade method and dried at 120 ℃ for 15 minutes. The thickness of the pressure-sensitive adhesive composition after drying was 25 μm. The sample was covered with another siliconized but more easily separable PET liner as the top layer.

Preparation of adhesive composition as second adhesive composition filled with desiccant

Three formulations for the desiccant-filled second adhesive composition according to the invention are listed in table 2, as well as three comparative adhesive compositions. The pressure sensitive adhesive compositions according to the invention are two pressure sensitive adhesive compositions (PSA1 and PSA2) and a liquid adhesive composition filled with a desiccant (LA 1). The amount of photoinitiator is related to the amount of epoxy resin used (information is given in weight percent with respect to the epoxy resin).

TABLE 2

In the case of the pressure-sensitive adhesive composition, the second adhesive composition filled with a desiccant is prepared and dried as described for the transparent first pressure-sensitive adhesive composition. The same is true for the comparative adhesive compositions. The preparation of liquid adhesive composition LA1 was carried out at room temperature by dispersing triarylsulfonium hexafluoroantimonate and calcium oxide in Uvacure.

Passing through a medium pressure mercury lamp at a rate of at least 400mJ/cm²The UV-C dose of (a) cures the activatable adhesive composition with the addition of the photoinitiator. In the present application, once curing has taken place, information about transparency, haze and penetration time is always related to the layer of adhesive composition after curing.

For the adhesive composition, the breakthrough times for different edge widths were determined (table 3), wherein here the entire area of the adhesive composition layer 22 was made of the relevant adhesive composition, since it was only intended to determine the material parameters. The desiccant-filled liquid adhesive LA1 was applied here at a thickness of 15 μm by adding some monodisperse PMMA spheres, and the other adhesive was applied at a thickness of 25 μm.

TABLE 3

Comparison of the opaque, highly desiccant filled second adhesive composition (PSA1, PSA2, LA1) according to the present invention with the desiccant filled adhesive composition (V1, V2) or the unfilled barrier adhesive composition (V3) according to the prior art clearly demonstrates the superior barrier effect of the highly filled, non-transparent adhesive composition.

Fig. 3 shows the breakthrough time as a function of the moisture scavenger content (i.e. desiccant content, here CaO) for an edge width of 1mm, wherein the entire face 22 is likewise of an adhesive composition (with a changed desiccant content) similar to the adhesive composition PSA 2. It is notable that technically useful breakthrough times can only be achieved from a desiccant content of 15% by weight. This is present with greater than 5 wt.% of the water absorption capacity of the second adhesive composition.

In addition, the following structures with an edge width a-a of 2mm were prepared for life testing:

examples	First adhesive composition	Second adhesive composition	Lag time [ h]
				B1	T1	PSA1	71
B2	T1	PSA2	415
				B3	T2	PSA1	52
B4	T2	PSA2	369
				B5	T1	LA1	1290
B6	T2	LA1	1309
				VB1	T1	V2(＝T1)	33
VB2	T2	V1	36
				VB3	T1	V3	19

TABLE 4

Here (as well as all other adhesive layers) a desiccant-filled liquid adhesive layer LA1 was made at a thickness of 25 μm, with the first adhesive composition acting as a spacer. The adhesive composition that was extruded from the side during joining was removed.

The penetration times determined in each case are listed in table 4. As expected, these are generally lower than the full area coating values with the desiccant-filled second adhesive composition, which may be attributed to manufacturing tolerances and errors. However, according to the present invention, there are significant advantages over full area encapsulation with a transparent first adhesive composition. Thus, since the calcium oxide content in the second adhesive composition (PSA1 vs. V1) increased by 50%, the breakthrough time increased correspondingly by about 100%, which also demonstrated a synergistic effect when the desiccant loading exceeded 15% or the water absorption was greater than 5% by weight.

As a result of the device according to the invention, the active side of the electronic device remains transparent encapsulated and the edge region is sealed in an improved manner by the highly desiccant-filled adhesive composition.

Claims

1. Protection method for protecting an organic electronic device arranged on a substrate, comprising the steps of

-applying a cover on the organic electronic device such that the organic electronic device is at least partially covered;

-affixing the covering with at least one layer of a first adhesive and at least one layer of a second adhesive,

it is characterized in that the preparation method is characterized in that,

-at least one layer of the first adhesive at least partially covers the organic electronic device and has a transparency of greater than 80% and a haze of less than 5%; and

-the at least one layer of the second adhesive surrounds the at least one layer of the first adhesive on a periphery of the at least one layer of the first adhesive, such that the at least one layer of the second adhesive forms an edge seal, wherein a width of the edge seal using the second adhesive does not exceed 2mm, and wherein the second adhesive has a water absorption capacity of more than 5 wt.%.

2. Protection process according to claim 1, characterized in that the second adhesive has a water absorption capacity of more than 10% by weight, in particular more than 14% by weight.

3. The method of claim 1 or 2, wherein the first adhesive comprises a desiccant.

4. The method of claim 3 wherein the difference in refractive index between the first adhesive and the desiccant is no greater than 0.02.

5. The protection method according to claim 3 or 4, characterized in that said first adhesive comprises hydrotalcite and/or a molecular-scale dispersed desiccant.

6. Protection method according to one of claims 1 to 5, characterized in that the second adhesive contains a desiccant, in particular calcium oxide.

7. The method of protection according to one of claims 1 to 6, characterized in that the first adhesive is applied in the form of a tape.

8. The protection method according to one of claims 1 to 7, characterized in that the second adhesive is applied in the form of a liquid adhesive.

9. The method of protection according to one of claims 1 to 8, characterized in that the first adhesive and the second adhesive have the same basic adhesive composition.

10. The protection method according to one of claims 1 to 9, characterized in that the second adhesive is applied at a distance from the organic electronic device.

11. An organic electronic structure comprising

-a substrate,

-an organic electronic device arranged on the substrate,

a cover at least partially covering the organic electronic device and at least partially adhered regionally to the substrate and/or the electronic device,

it is characterized in that the preparation method is characterized in that,

the structural body further includes:

-at least one layer of a first adhesive at least partially covering the organic electronic device and having a transparency of more than 80% and a haze of less than 5%,

-at least one layer of a second adhesive surrounding the at least one layer of the first adhesive on a periphery of the at least one layer of the first adhesive, such that the at least one layer of the second adhesive forms an edge seal, wherein the width of the edge seal using the second adhesive does not exceed 2mm, and wherein the second adhesive has a water absorption capacity of more than 5 wt.%.

12. The organic electronic structure of claim 11, wherein the second adhesive has a water absorption capacity of greater than 10 wt.%, particularly greater than 14 wt.%.

13. The organic electronic structure according to claim 11 or 12, characterized in that the second binder comprises a drying agent, in particular calcium oxide.

14. The organic electronic structure of any of claims 11 to 13, wherein the first adhesive comprises a desiccant.

15. The organic electronic structure according to one of claims 11 to 14, characterized in that the first binder comprises hydrotalcite and/or a molecular-scale dispersed desiccant as desiccant.

16. The organic electronic structure of any of claims 11 to 15, wherein the first adhesive and the second adhesive have the same base adhesive composition.

17. The organic electronic structure according to any one of claims 11 to 16, wherein the cover completely covers the electronic device.

18. The organic electronic structure of any of claims 11 to 17, wherein the layer of the second adhesive completely surrounds the organic electronic device.

19. The organic electronic structure of any of claims 11 to 18, wherein the second adhesive is applied at a distance from the organic electronic device.