WO2019223953A1 - Combination of a transparent full-area encapsulation with a (non-transparent) edge encapsulation having a high getter content - Google Patents

Abstract

The invention relates to an organic electronic structure, comprising a substrate, an organic electronic assembly arranged on the substrate, a cover, which at least partially covers the organic electronic assembly and is adhesively bonded, at least over a partial area, to the substrate and/or to the electronic assembly, the structure also comprising at least one layer of a first adhesive, which layer at least partially covers the organic electronic assembly and has a transparency of more than 80% and a haze of less than 5%, and at least one layer of a second adhesive, which layer surrounds the at least one layer of the first adhesive at the periphery thereof such that the at least one layer of the second adhesive forms an edge encapsulation, the width of the edge encapsulation with the second adhesive being no more than 2 mm, and the second adhesive having a water absorption capacity of more than 5 wt.%, which enables small widths for the edge regions around displays or other organic electronic structures.

Description

 Combination of a transparent full-surface encapsulation with an (intransparent) edge encapsulation with a high getter content

The present invention relates to a protective method for protecting an organic electronic device disposed on a substrate, comprising the steps of attaching a cover over the organic electronic device such that the organic electronic device is at least partially covered, and adhering the cover to at least one layer a first adhesive and at least one layer of a second adhesive. Furthermore, the invention relates to an organic electronic structure, comprising a substrate, an organic electronic arrangement arranged on the substrate and a cover which at least partially covers the organic electronic arrangement and adheres at least partially to the substrate and / or to the organic electronic arrangement is.

(Opto) electronic devices are increasingly used in commercial products. Such arrangements include inorganic or organic electronic structures, such as organic, organometallic or polymeric semiconductors or combinations thereof. These arrangements and products are rigid or flexible depending on the desired application, whereby there is an increasing demand for flexible arrangements. The production of such arrangements is effected for example by printing processes such as high-pressure, intaglio, screen printing, planographic printing or as well as so-called "non-impact printing" such as thermal transfer inkjet printing or digital printing. In many cases, however, vacuum processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced chemical or physical deposition (PECVD), sputtering, (plasma) etching or vapor deposition are used, the patterning usually by masks he follows.

Electrophoretic or electrochromic structures or displays, organic or polymeric light-emitting diodes (OLEDs or PLEDs) in display and display devices or as illumination may be mentioned as examples of (commercial) electronic applications that are already commercially interesting or in their market potential. Electroluminescent lamps, light-emitting electrochemical cells

(LEECs), organic solar cells, preferably dye or polymer solar cells, inorganic solar cells, preferably thin-film solar cells, in particular based on silicon, germanium, copper, indium and selenium, organic field effect transistors, organic switching elements, organic optical amplifiers, organic laser diodes, organic or inorganic sensors or also organic or inorganic based RFID transponders.

Accordingly, in this document an organic (opto) electronic arrangement is understood to mean an electronic arrangement which comprises at least one electronically functional, at least partially organic component, such as, for example, organometallic compounds.

As a technical challenge for the realization of sufficient life and function of (opto) electronic arrangements in the field of inorganic and / or organic (opto) electronics, but especially in the field of organic (opto) electronics is a protection of the components contained therein to see before permeates. Permeates may be a variety of low molecular weight organic or inorganic compounds, especially water vapor and oxygen.

A large number of (opto) electronic arrangements in the field of inorganic and / or organic (optoelectronic) electronics, especially when using organic raw materials, are sensitive to both water vapor and oxygen, and for many arrangements the penetration of Water or steam is classified as a major problem. Therefore, encapsulation protection is required during the lifetime of the electronic device, otherwise performance will degrade over the period of use. Thus, for example, by an oxidation of the components such as in light-emitting devices such as electroluminescent lamps (EL lamps) or organic light-emitting diodes (OLED), the luminosity, in electrophoretic displays (EP displays) the contrast or in solar cells efficiency within a very short time to decrease. The full-surface encapsulation by means of an adhesive or an adhesive tape which completely covers the organic electronic structure applied to a substrate as well as an edge region and connects this region with a permeation-tight cover has proven successful. For light-emitting or consuming structures, this adhesive layer must be highly transparent and have low haze.

To achieve a long service life of the structures, it is advantageous to coat the adhesive with a catcher material, e.g. to provide a desiccant to provide barrier action against the permeating permeates.

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 usually stated. The respective rate indicates the area- and time-related flow of oxygen or water vapor through a film under specific conditions of temperature and partial pressure and optionally other measurement conditions such as relative humidity. The lower these values are, the better the respective material is suitable for encapsulation. The specification of the permeation is based not only on the values for WVTR or OTR, but always includes an indication of the mean path length of the permeation such as the thickness of the material or a normalization to a certain path length.

The permeability P is a measure of the permeability of a body to gases and / or liquids. A low P value indicates a good barrier effect. The permeability P is a specific value for a defined material and a defined permeate under steady state conditions at a certain permeation path length, partial pressure and temperature. The permeability P is the product of diffusion term D and solubility term S: P = D ^* S.

The solubility term S predominantly describes the affinity of the barrier adhesive to the permeate. For example, in the case of water vapor, a small value for S of hydrophobic materials is achieved. The diffusion term D is a measure of the mobility of the permeate in the barrier material and is directly dependent on properties such as molecular mobility or free volume. They are often added strongly cross-linked or highly crystalline materials for D achieved relatively low values. However, highly crystalline materials tend to be less transparent, and greater crosslinking results in less flexibility. The permeability P usually increases with an increase in molecular mobility, such as when the temperature is increased or the glass transition point is exceeded.

Approaches to increase the barrier effect of an adhesive must consider the two parameters D and S in particular with regard to the influence on the permeability of water vapor and oxygen. In addition to these chemical properties, effects of physical influences on the permeability must also be considered, in particular the mean permeation path length and interfacial properties (flow behavior of the adhesive, adhesion). The ideal barrier adhesive has low D values and S values with very good adhesion to the substrate.

A low solubility term S alone is usually insufficient to achieve good barrier properties. A classic example of this is in particular siloxane elastomers. The materials are extremely hydrophobic (small solubility term), but have a comparatively low barrier to water vapor and oxygen due to their freely rotatable Si-O bond (large diffusion term). For a good barrier effect, therefore, a good balance between solubility term S and diffusion term D is necessary.

If highly efficient particulate desiccants such as calcium oxide or zeolites are used to achieve good barrier properties, however, this leads to an increase in the haze, which, as stated above, is problematic for light-emitting or light-consuming structures. Due to the high refractive index of these desiccants (calcium oxide: 1, 86) is at usual

Encapsulating adhesives already at a level of 2% by weight of the haze are significantly greater than 5%. Transparency and haze-preserving desiccants such as silanes are known but less efficient.

As an alternative to the full-surface encapsulation, therefore, marginal encapsulation can also be carried out in order to maintain transparency in the relevant region of the structure, with only one surface enclosing the electronic structure having the Encapsulating adhesive is provided. This can be filled to a high degree with efficient desiccant since no special optical requirements have to be met in the edge area. The disadvantage here is the remaining cavity in the encapsulated arrangement. Arrangements are therefore also known in which an edge encapsulation and a full-surface encapsulation are combined.

An edge encapsulation with a sealant is known, for example, from W02009085736. This discloses a solar cell panel, which is covered over its entire surface with a desiccant-free adhesive layer and has a Randverkapselung with a desiccant-containing sealing material. The sealing material is applied in liquid form from the melt.

US 2008/0289681 A1 discloses a solar cell module in which solar cells are applied to a substrate via a potting compound layer. Another layer of potting compound covers the solar cells with a transparent cover layer. The module may further comprise a desiccant-containing edge encapsulation, which has a width of 5 - 20 mm. As a desiccant zeolite is used. Preferred embodiments of the Randverkapselungen are hot melt film and hot melt paste.

No. 6,936,131 B2 describes the use of desiccant-filled transfer adhesive tapes which can be used as full-surface encapsulation or as edge encapsulation. As a desiccant inorganic particles are described. The particles used in the examples lead to a high haze of the adhesive.

US20070013292A1 discloses an organic electronic structure which is provided with a desiccant-containing edge encapsulation. This can be designed as a curable adhesive, also as an adhesive tape. The width of the edge encapsulation is preferably carried out above 2 mm.

In the field of mobile electronic devices, the trend is towards ever narrower edges around displays. The web width of the bonding area outside the active area is often not more than 2 mm. In such arrangements, the limit of performance is highly transparent and low light-scattering encapsulation adhesives achieved, the life no longer meets the requirements, since the small distance from the environment to the active surface in too short time by penetrating permeation, especially water vapor, is passed, which then leads to destruction. This time span is called Lag-Time.

A difficulty that these small web widths entail is still the tolerance in the application: a dry medium-containing edge encapsulation arranged outside the active surface must under no circumstances protrude into the active surface or flow into it during application. For tolerance reasons, therefore, it is not possible to use the entire, in any case small, web width for highly efficient edge encapsulation.

The object of the present invention was therefore to provide an improved encapsulation of a narrow-edged organic electronic structure, which allows an improved utilization of the narrow edge for the permeation barrier and thus better protects the encapsulated object against the ingress of moisture, without impairing the optical properties of the organic electronic structure with it.

This object is achieved by a protective method of the type mentioned above in that the at least one layer of the first adhesive at least partially covers the organic electronic device and has a transparency of more than 80% and a haze of less than 5% and the at least one layer the second adhesive comprising at least one layer of the first adhesive at its periphery to form an edge encapsulation, wherein the width of the edge encapsulation with the second adhesive is not more than 2 mm (ie two mm or less), and wherein the second adhesive a water absorption capacity, ie Water absorption capacity, of more than 5 wt .-%.

Further, according to the present invention, there is provided an organic electronic structure of the aforementioned type, wherein the structure further comprises at least one layer of a first adhesive at least partially covering the organic electronic device and a transparency of more than 80% and a haze of less than 5%, as well as at least one layer of a second adhesive comprising the at least one layer of the first adhesive at its periphery comprises, so that it forms a Randverkapselung, wherein the width of the edge encapsulation with the second adhesive is not more than 2 mm, and having a water absorbency of more than 5 wt .-% comprises.

There is thus a combination of a first transparent full-surface encapsulation with a second (non-transparent) edge encapsulation with high water absorption capacity.

Preferred embodiments of the method and the organic electronic structure are in the subclaims. The preferred embodiments of the method apply analogously to the organic electronic structure and vice versa.

Preference is given to an embodiment of the organic electronic structure in which there is no further polymeric layer between the cover and the organic electronic arrangement, ie only the at least one, in particular only one, layer of the first adhesive as the polymeric layer and no further layers are present.

A polymer is a chemical compound consisting of usually organic chain or branched molecules (macromolecule) consisting of the same, similar or different units (the so-called monomers). In the simplest case, the macromolecule consists of only one type of monomer. Copolymers are made up of various monomers which can be distributed randomly in the macromolecule, distributed regularly or in blocks. Polymers contain at least three identical monomer units. A monomer unit within the meaning of this definition is the bonded form of a monomer in a polymer.

Also, a structure is particularly favorable, in which the organic electronic device is located directly on the substrate.

Likewise, a construction is particularly favorable in which the organic electronic arrangement arranged on a substrate is already provided with a primary encapsulation, for example a thin-layer encapsulation, and the method claimed here Secondary encapsulation is performed on one or both sides of the arranged on the substrate electronic device.

The cover at least partially covers the organic electronic device. Preferably, it completely covers the organic electronic device.

The at least one layer of the first adhesive at least partially covers the organic electronic device. Preferably, it completely covers the organic electronic device.

Preference is given to a structure in which the second adhesive does not touch or cover the organic electronic device, ie a structure in which the second adhesive is applied at a distance from the organic electronic device. The distance at which the adhesive is applied to the organic electronic arrangement is preferably from 0.1 mm to 2 mm, in particular from 0.2 mm to 1 mm and particularly preferably from 0.2 mm to 0.5 mm.

In a preferred embodiment, the distance formed in this way is filled with the first adhesive. If the organic electronic arrangement is surrounded by a primary encapsulation, then in another preferred embodiment the distance is filled by 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 adhesives can be presented as liquid or pasty adhesives or in the form of adhesive tapes. The use of adhesive tapes is particularly preferred because it allows a good, namely particularly accurate and very simple, application of the adhesive.

The thickness of the adhesive layer of first or second adhesive is preferably between about 4 pm and about 250 pm. The adhesive thickness is particularly preferably not more than 50 μm, in particular not more than 25 μm. In principle, any adhesive described in the prior art (for example in G. Habenicht: Kleben, 6th edition, Springer 2009) can be used as the adhesive. Examples of such adhesives are, without thereby wanting to unnecessarily limit the invention, those based on vinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl chloride, (meth) acrylate, polyamide and its copolymers, cellulose, urea, melamine resin, phenolic resin, epoxy, polyurethane, polyester , Polyaromatic, chloroprene, nitrile rubber, styrene, butyl rubber, polysulfide or silicone. Also mixtures are according to the invention. Preferably, an activatable adhesive is used.

The first adhesive is preferably a pressure-sensitive adhesive. Activatable PSAs are particularly preferably used. More preferably, the first adhesive is presented as a pressure-sensitive adhesive tape. This facilitates the processing of the adhesive.

Adhesive adhesives are adhesives which, even under relatively slight pressure, permit a permanent bond with the primer and, after use, can be removed again from the primer without leaving any residue. Pressure-sensitive adhesives are permanently tacky at room temperature and therefore have a sufficiently low viscosity and high tack, so that they wet the surface of the respective adhesive base even at low pressure. The adhesiveness of the adhesives is based on their adhesive properties and the removability on their cohesive properties. As a basis for PSAs, various compounds come into question.

As PSAs, it is possible to use all PSAs known to the person skilled in the art, for example those based on acrylates and / or methacrylates, polyurethanes, natural rubbers, synthetic rubbers, styrene block copolymer compositions with an elastomeric block of unsaturated or hydrogenated polydiene blocks (polybutadiene, polyisoprene, copolymers of both, and others). Elastomer blocks familiar to the person skilled in the art), polyolefins, fluoropolymers and / or silicones. This also includes other compositions which have pressure-sensitive adhesive properties in accordance with the Handbook of Pressure Sensitive Adhesive Technology by Donatas Satas (Satas & Associates, Warwick 1999). Adhesive systems are considered as activatable adhesives, in which the production of the final adhesion by an energy input, for example by actinic radiation or heat takes place.

As activatable adhesive, it is possible in principle to use all customary adhesively bonded adhesive systems that are activated. Activation is usually via an energy input, e.g. by actinic radiation, heat or mechanical energy, such. As ultrasound or friction.

Heat-activated adhesive adhesives can basically be classified into two categories: thermoplastic heat-activated adhesives (hot-melt adhesives) and reactive heat-activated adhesives (reactive adhesives). This classification also contains such adhesives, which can be assigned to both categories, namely reactive thermoplastic heat-activated adhesive adhesives (reactive hot melt adhesives).

Thermoplastic adhesives are based on polymers that reversibly soften when heated and solidify again during cooling. Particularly suitable thermoplastic adhesives have been found to be advantageous on the basis of polyolefins and copolymers of polyolefins and of their acid-modified derivatives, of ionomers, of thermoplastic polyurethanes, of polyamides and polyesters and copolymers thereof, and also of block copolymers such as styrene block copolymers.

In contrast, reactive heat-activated adhesive adhesives contain reactive components. The latter constituents are also referred to as "reactive resins" in which the heating initiates a crosslinking process which, upon completion of the crosslinking reaction, ensures a permanent stable compound. Such adhesives preferably also contain elastic components, for example synthetic nitrile rubbers or styrene block copolymers. Due to their high flow viscosity, such elastic components impart to the heat-activated adhesive composition a particularly high dimensional stability, even under pressure. Radiation-activated adhesives are also based on reactive

Components. The latter ingredients may e.g. Include polymers or reactive resins in which the irradiation initiates a crosslinking process which, upon completion of the crosslinking reaction, ensures a durable, stable compound. Such adhesives preferably also contain elastic components, as stated above.

Radiation-activable PSAs are to be distinguished from radiation-crosslinked PSAs in which the pressure-sensitively adhesive properties are set by radiation crosslinking during the production of the adhesive tape. In the case of radiation-activable PSAs, the radiation activation takes place during application. After radiation activation, the adhesive is generally no longer tacky.

Activatable pressure-sensitive adhesive tapes also comprise pressure-sensitive adhesive tapes assembled from two or more adhesive films, as disclosed in DE 10 2013 222739 A1. These are activated by contacting the two or more adhesive films.

Particularly suitable are those activatable (adhesive) adhesive compositions which are prepared from compounds which have at least one of the following functional groups: epoxides, amines, ureido groups, hydroxyl groups, ether groups, acid groups, in particular carboxylic acid groups, preferably acrylic acid and methacrylic acid groups, and carboxylic anhydride groups, ester groups and amide groups, isocyanates, imidazoles, phenolic groups, urea groups, silane groups, ethylenic double bonds, especially in combination with initiator groups that can initiate radical polymerization or with sulfur-containing vulcanizing agents.

The activatable (adhesive) adhesives may optionally contain one or more other formulation ingredients such as hardeners, reaction accelerators, catalysts, initiators, fillers, microspheres, tackifier resins, non-reactive resins, plasticizers, binders, bitumen, anti-aging agents (antioxidants), light stabilizers, UV Absorber, rheological additives, and other auxiliaries and additives may be included. Examples of (barrier) adhesives which are particularly suitable for the present invention can be found in US 2006/0100299 A1, WO 2007/087281 A1, EP 2166593 A1, EP 2279537 B1, EP 2465149 B1, EP 2768919 B1, EP 2768918 A1, EP 2838968 A1, EP 2838968 A1 or WO 2016066435 A1, this list being purely exemplary and in no way exhaustive.

The second adhesive may also be a pressure-sensitive adhesive and also be designed as a pressure-sensitive adhesive tape. However, particularly preferred is the execution of the second adhesive as a liquid adhesive.

Preferably, the second adhesive contains a desiccant. However, the water-catching property may also be due to the adhesive itself. As an example, not fully reacted epoxide may be mentioned here.

As a desiccant in the second adhesive can be used in principle all known in the art desiccant. If desiccants are also used in the first adhesive, these are preferably those which do not or only slightly impair the transparency of the adhesive.

Water vapor entering the (opto) electronic device is then bound chemically or physically, preferably chemically, to these substances, thus increasing the "lag-time." Desiccants are also referred to in the literature as "getters," "scavengers." The term "desiccant" is used herein to refer to either the adsorption of silica gel, molecular sieves, zeolites or sodium sulphate, such as alkoxysilanes, oxazolidines, isocyanates, Barium oxide, phosphorus pentoxide, alkali metal and alkaline earth metal oxides (such as, for example, calcium oxide), metallic calcium or metal hydrides are bonded (WO 2004/009720 A2) However, many fillers are not suitable for the transparent bonding of, for example, displays with the first adhesive, since the transparency and in particular the haze of the adhesive is reduced.

As such desiccants are described in adhesives mainly inorganic fillers such as calcium chloride or various oxides (see US 5,304,419 A, EP 2 380 930 A1 or US 6,936,131 A). Such adhesives dominate in the case of edge encapsulation, that is to say in cases in which only edges are to be glued. For a full-surface encapsulation, however, adhesives containing such getters are unsuitable since, as stated above, they reduce the transparency and in particular the haze.

Organic getters are also described in adhesives. For example, in EP 2 597 697 A1, in which polymeric alkoxysilanes are used as drying agents. Numerous different silanes as drying agents in adhesives are mentioned in WO 2014/001005 A1. According to this document, the maximum amount of desiccant to be used is 2% by weight, since the use of larger mass fractions would damage the sensitive electronic structure to be encapsulated. The problem is that the organic desiccants used are usually very reactive and cause damage (so-called "dark spots") on contact with the sensitive organic electronics in the full-surface encapsulation.Adhesives containing such desiccants are thus preferably suitable for edge encapsulation (second adhesive) in which there is no direct contact of the adhesive with the electronic device.

Preference is given to using a drying agent whose water absorption capacity is more than 10% by weight, particularly preferably more than 20% by weight. As a result, the proportion of the desiccant in the adhesive can be kept lower and thus the adhesive properties are less affected.

Particularly preferred is calcium oxide as a drying agent. This has a high water absorption capacity of more than 20 wt .-%, the water absorbs slowly enough, so that in the production of the adhesive, the drying capacity is largely retained, and binds the water without changing its physical shape, without itself eg to liquefy.

Preferably, the desiccant content of the second adhesive is 15% by weight or more, more preferably 30% by weight or more. In a further preferred adhesive with 40 wt .-% or more desiccant, the administration is preferred as a liquid adhesive, since the high filler content affects the pressure-sensitive adhesive properties of an adhesive tape. Most preferably, the above two embodiments are combined. Thus, preferably the desiccant content of an adhesive is more than 20 wt .-%, said desiccant having a water absorption capacity of more than 10 wt .-%, particularly preferably more than 20 wt .-%, having.

Particular preference is given to a desiccant-containing second adhesive which has a water absorption capacity 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-catching properties, in particular the first adhesive, which is preferably a full-surface encapsulation, contains a water scavenger, typically a desiccant.

The first adhesive preferably contains less than 2% by weight particulate desiccant, in particular calcium oxide, since the high refractive index of many desiccants (calcium oxide: 1.86) in conventional encapsulation adhesives already accounts for more than 2% by weight of the haze usually greater than 5%.

Preferably, the base adhesive, ie the adhesive formulation without any added desiccant, the first adhesive and / or the second adhesive has a water vapor transmission rate (WVTR) of less than 100 g / m ² d at 38 ° C / 90% relative humidity, based on a Layer thickness of 50 pm, more preferably less than 20 g / m ² d. Preference is given to adhesives based on polybutylenes, such as, for example, butyl rubber, in particular based on modified or unmodified polyisobutylene.

Examples of such adhesives are: WO2013057265 (copolymers of isobutylene or butylene), DE102008047964A1 (vinylaromatic block copolymers), US8557084B2 (crosslinked vinylaromatic block copolymers), EP2200105 (polyolefins), US8460969B2 (butylene block copolymer, WO02007087281A1 (hydrogenated cycloolefin polymers with PIB), W02009148722 (PIB with acrylate reactive resin), EP2502962A1 (PiB-epoxy), JP2015197969 (PIB).

Preferably, the first adhesive, the full-area encapsulant, and the second adhesive, the edge-encapsulant, are based on the same Base adhesive. This means that the components of the adhesives which dominate the adhesive performance are substantially the same, and the proportions of the constituents are also substantially the same. In particular, the base polymer or the base polymers of both adhesives is the same.

"Base adhesive", "based on" or "based on" means in this case that the properties of the adhesive are at least strongly determined by the basic properties of the base adhesive or of one or more base polymers or monomers, it being understood that it is not excluded that that these are additionally influenced by the use of modifying auxiliaries or additives or by other polymers or monomers in the composition. In particular, this may mean that the proportion of the base polymer or of the base polymers and optionally of the monomers in the total mass of the polymeric phase is more than 50% by weight.

Preferably, in the transparent first adhesive is a desiccant which has a similar refractive index as typical encapsulating adhesives and thus enables a highly transparent adhesive. A similar refractive index is understood to mean a difference in refractive index between the first adhesive and desiccant of not more than 0.02. Hydrotalcite is particularly preferably used as drying agent. Well suited, for example, the synthetic hydrotalcite (Mg ₆ Al ₂ (C0 ₃ ) (0H) i ₆ 4H ₂ 0, product number 652288) from. Sigma-Aldrich.

Preferably, the particular full-surface first adhesive is free of particulate fillers, as these increase the Haze.

Preferably, the transparent first adhesive comprises a molecularly dispersed desiccant.

Preferably, the first adhesive is applied as a sheet (adhesive tape), the second as a liquid adhesive. According to the invention, a method in which first a first adhesive is applied as an adhesive tape to the electronic device (which is usually arranged on a substrate) or its cover and then around this a liquid adhesive as a second adhesive. Finally, the joining of electronic arrangement and cover takes place, the first adhesive serving as a spacer and significantly reducing squeezing of the second adhesive.

Preferably, the width of the edge encapsulation with the second (encapsulant) adhesive is not more than two millimeters, more preferably less than one millimeter, because it maximizes the ratio of active area to total area of the electronic package. For example, In the case of displays such a structure is perceived by the user as visually very appealing.

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

Characters:

Fig. 1 shows a calcium test as a measure for determining the life of an electronic structure. 2 shows by way of example a curve as it results from the measured data of the test. FIG. 3 shows by way of example the breakthrough time as a function of the water scavenger content. Three individually preferred embodiments of organic electronic structures according to the invention are shown in the attached Figures 4 to 6. 4 shows an organic electronic structure in a simple form with organic electronic arrangement applied to the substrate and the cover applied by means of the two adhesives; Fig. 5 is an organic electronic structure having a primary encapsulation 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. It means:

 1: organic electronic construction

2: substrate

 3: organic electronic arrangement

4: cover

5: first adhesive

6: second adhesive

 7: Primary encapsulation, e.g. TFE

 8: second cover, arranged on the first cover opposite surface of the body.

The organic electronic structure 1 shown in FIG. 4 includes an organic electronic device 3 mounted on a substrate 2. The organic electronic device 3 is completely surrounded by a second adhesive 6, with a certain distance from the organic electronic device 3. The second adhesive 6 has a good water absorbency. The organic electronic device 3 is covered with a first adhesive 5. This also fills the gap between the organic electronic device 3 and the second adhesive 6. The layer of the first adhesive 5 has a transparency of> 80%, so that there are no impairments in the function of the underlying organic electronic device 3.

The organic electronic structure 1 shown in FIG. 5 corresponds in its basic structure to that shown in FIG. 4. In addition, it includes a primary encapsulation 7. This may be, for example, a thin-layer encapsulation. The primary encapsulant 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, this organic electronic structure also has a second cover 8, which is arranged on the surface of the structure opposite the first cover 4.

The organic electronic structure 1 shown in FIG. 6 corresponds in its basic structure to that shown in FIG. 4. In addition, it includes a primary encapsulation 7. This may be, for example, a thin-layer encapsulation. The primary encapsulation 7 shown in FIG. 5 completely covers the organic electronic device 3 and fills a partial area of the distance between the second adhesive 6 and the organic electronic device 3. Another portion of the gap is filled by the first adhesive. The second adhesive is bonded to at least a portion of the primary encapsulation.

Measurement Methods:

The measurements are, unless otherwise stated, at a test climate of 23 ± 1 ° C and 50 ± 5% rel. Humidity carried out.

Water vapor permeation rate (WVTR):

The WVTR is measured at 38 ° C and 90% relative humidity according to ASTM F-1249-13. In each case a double determination is carried out and the mean value is formed. The specified value is normalized to a thickness of 50 μm. The adhesives, in particular transfer adhesive tapes, are bonded to a highly permeable polysulfone membrane (available from Sartorius) for the measurements, which itself does not contribute to the permeation barrier.

Water absorption capacity of the adhesive:

The water absorption is determined according to DIN EN ISO 62: 2008-05 (gravimetric method, method 4) after storage of the test specimen for 7 days at 23 ° C and 50% relative humidity. In each case, a triple determination is carried out on a specimen having an area of 250 cm ² and a thickness of 50 μm. The water content is the arithmetic mean of the measurements in% by weight.

Water absorption capacity of the desiccant:

The water absorption is determined in accordance with DIN EN ISO 62: 2008-05 (gravimetric method, method 4) after storage of the test specimen for 7 days at 23 ° C and 50% relative humidity. In each case a triple determination is carried out on about 10 g of the drying agent. The water content is the arithmetic mean of the measurements in% by weight. Determination of the breakthrough time (lag time):

As a measure of the determination of the lifetime of an electronic structure, a calcium test was used. This is shown in FIG. For this purpose, a usually 10 x 10 mm ² large, thin calcium layer 23 is deposited on a glass plate 21 in a vacuum and then stored under a nitrogen atmosphere. The thickness of the calcium layer 23 is about 100 nm. For the encapsulation of the calcium layer 23, a layer (23 × 23 mm ² ) with the adhesive 22 to be tested and a thin glass pane 24 (35 μm, Schott) is used as the carrier material. For stabilization, the thin glass pane was laminated with a 100 μm thick PET film 26 by means of a 50 μm thick transfer adhesive tape 25 of an optically highly transparent acrylic PSA. The adhesive 22 is applied to the glass plate 21 in such a way that the adhesive 22 covers the calcium mirror 23 with an edge of 6.5 mm (AA) protruding on all sides.

In order to achieve different edge widths, the size of the calcium level is varied. According to the invention, the adhesive layer 22 was, unless stated otherwise, made of a transparent first encapsulant adhesive which covers the Ca level and of a desiccant-filled second encapsulant which covers the peripheral edge area of the width A-A. Due to the opaque glass carrier 24, only the permeation through the adhesive or along the interfaces is determined.

The test is based on the reaction of calcium with water vapor and oxygen, as described for example by AG Erlat et. al. in "47th Annual Technical Conference Proceedings Society of Vacuum Coaters", 2004, pages 654 to 659, and by ME Gross et al., in "46th Annual Technical Conference Proceedings Society of Vacuum Coaters", 2003, pages 89 to 92 are. In this case, the light transmission of the calcium layer is monitored, which increases by the conversion into calcium hydroxide and calcium oxide. This takes place in the described test setup from the edge, so that the visible surface of the calcium level is reduced. It is called the time to halving the light absorption of the calcium level as a lifetime. By doing so, both the degradation of the area of the calcium level detected from the edge and by selective degradation in the area as well as the homogeneous reduction of the layer thickness of the calcium level by full-scale degradation.

The measurement conditions selected were 85 ° C and 85% relative humidity (RH). The samples were glued with a layer thickness of the adhesive of 25 pm over the entire surface and without bubbles, unless stated otherwise. The degradation of the Ca level is monitored by transmission measurements. The lag time is defined as the time it takes for moisture to travel the distance A-A to the edge of the Ca mirror (see Figure 1). From the observation of the transmission, the breakthrough time can be read as the intersection of a straight line through the measured values in the essentially constant initial phase with a straight line through the measured values of the steady increase in the transmission (= decrease in the absorption, see FIG. The measured value (in h) is the average of three individual measurements. 2 shows by way of example a curve as it results from the measured data of the test.

Molecular weight:

The molecular weight determinations of the number-average molecular weights M _n and the weight-average molecular weights M _{w were} carried out by means of gel permeation chromatography (GPC). The eluent used was THF (tetrahydrofuran) containing 0.1% by volume of trifluoroacetic acid. The measurement was carried out at 25 ° C. The precolumn used was PSS-SDV, 5 m, 10 ³ A, ID 8.0 mm × 50 mm. For separation, the columns PSS-SDV, 5 m, 10 ³ Ä and 10 ⁵ Ä and 10 ⁶ Ä were used with each ID 8.0 mm x 300 mm. The sample concentration was 4 g / l, the flow rate 1, 0 ml per minute. It was measured against polystyrene standards.

softening temperature:

The adhesive resin softening temperature is carried out according to the relevant method known as Ring and Ball, which is standardized according to ASTM E28-14.

To determine the adhesive resin softening temperature of the resins, a ring-ball automat HRB 754 from Herzog is used. Resin patterns are first finely pounded. The resulting powder is placed in a brass cylinder with bottom opening (inner diameter at the upper part of the cylinder 20 mm, diameter of the bottom opening of the cylinder 16 mm, height of the cylinder 6 mm) and melted on a heating table. The filling quantity is chosen so that the resin after melting completely fills the cylinder without supernatant.

The resulting specimen, including the cylinder, is inserted in the sample holder of the HRB 754. Glycerol is used to fill the tempering bath, provided that the adhesive resin softening temperature is between 50 ° C and 150 ° C. At lower Klebharzerweichungstemperaturen can also be used with a water bath. The test balls have a diameter of 9.5 mm and weigh 3.5 g. In accordance with the HRB 754 procedure, the ball is placed above the specimen in the temperature control bath and deposited on the specimen. 25 mm below the cylinder bottom there is a catch plate, 2 mm above this a light barrier. During the measuring process, the temperature is increased at 5 ° C / min. In the temperature range of the adhesive resin softening temperature, the ball begins to move through the bottom opening of the cylinder until it eventually stops on the catch plate. In this position, it is detected by the photocell and registered at this time, the temperature of the bath. There is a double determination. The adhesive resin softening temperature is the average of the two individual measurements.

MMAP and DACP

MMAP:

The MMAP is the methylcyclohexane aniline cloud point determined using a modified ASTM D-5773-17e1 method. In a dry sample glass, 5.0 g of test substance (the adhesive resin sample to be examined) are weighed and mixed with 10 mL of dry aniline (CAS [62-53-3],> 99.5%, Sigma-Aldrich # 51788 or equivalent) and 5 mL dry methylcyclohexane (CAS [108-87-2],> 99%, Sigma-Aldrich # 300306 or equivalent). The sample glass is shaken until the test substance has completely dissolved. For this purpose, the solution is heated to 100 ° C. The sample glass with the resin solution is then introduced into a cloud point measuring device Chemotronic Cool from Novomatics and there tempered to 1 10 ° C. With a cooling rate of 1, 0 K / min is cooled. The cloud point is optically detected. For this purpose, the temperature is recorded at which the turbidity of the solution is 70%. The result is given in ° C. The lower the MMAP value, the higher the aromaticity of the test substance.

DACP:

The DACP is the diacetone cloud point. 5.0 g of test substance (the adhesive resin sample to be investigated) are weighed into a dry sample glass and mixed with 5.0 g of xylene (mixture of isomers, CAS [1330-20-7],> 98.5%, Sigma-Aldrich # 320579 or similar). bar). At 130 ° C, the test substance is dissolved and then cooled to 80 ° C. Any escaped xylene is filled in with additional xylene, so that again 5.0 g of xylene are present. Subsequently, 5.0 g of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich # H41544 or equivalent) are added. The sample glass is shaken until the test substance has completely dissolved. For this purpose, the solution is heated to 100 ° C. The sample glass with the resin solution is then introduced into a cloud point measuring device Chemotronic Cool from Novomatics and tempered there to 1 10 ° C. With a cooling rate of 1, 0 K / min is cooled. The cloud point is optically detected. For this purpose, the temperature is recorded at which the turbidity of the solution is 70%. The result is given in ° C. The lower the DACP value, the higher the polarity of the test substance.

Transparency:

The transparency (transmission) of the adhesive layer was determined in accordance with ASTM D1003-13 (Procedure A (Hazard Byk Haze-gard Dual), standard illuminant D65). A correction of interfacial reflection losses is not made.

Haze:

The HAZE value describes the proportion of the transmitted light, which is scattered by the irradiated sample (adhesive layer) forward at a large angle. Thus, the HAZE value quantifies structures in the surface or in the volume that interfere with clear vision. The method for measuring the Haze value is described in the Standard ASTM D 1003-13 described. The standard requires the measurement of four transmission measurements. For each transmission measurement, the light transmittance is calculated. The four transmittances are calculated as the percentage Haze value. The HAZE value is measured using a Haze-gard Dual from Byk-Gardner GmbH.

Refractive index:

The refractive index is determined on the basis of ISO 489 (method A, measuring wavelength 589 nm) at a temperature of 20 ° C. and a relative air humidity of 50%. Cinnamon oil was used as the contact liquid in the measurement.

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

Glass transition temperature (T _g ):

Glass transition points - referred to interchangeably as glass transition temperatures - are reported as the result of differential scanning calorimetry (DSK) measurements in accordance with DIN 53 765: 1994-03; in particular Sections 7.1 and 8.1, but with uniform heating and cooling rates of 10 K / min in all heating and cooling steps (see DIN 53 765: 1994-03, Section 7.1, note 1). The sample weight is 20 mg.

Examples:

Used components:

Unless otherwise stated, all quantities in the following examples are percentages by weight or parts by weight. The parts by weight are based on the total composition without photoinitiator and without solvent. The amount of photoinitiator refers to the amount of epoxy resin used (in percent by weight). SibStar 62 M: SiBS (polystyrene block polyisobutylene block copolymer) from Kaneka with 20 wt .-% block polystyrene content. M _w = 60,000 g / mol, the glass transition temperature of the polystyrene blocks is 100 ° C and that of the polyisobutylene blocks -60 ° C.

Uvacure 1500: cycloaliphatic diepoxide (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate) from Cytec, viscosity at 23 ° C. about 300 mPas

Regalite R1 100: a fully hydrogenated hydrocarbon resin from Eastman (Ring and Ball softening temperature 100 ° C, DACP = 71 ° C, MMAP = 76 ° C)

TerPIB 950: polyisobutylene from TerHell with a weight-average molecular weight of 950 g / mol

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

Caloxol CP2: Calcium oxide from Omya Chemicals, water absorption capacity approx. 40% by weight

Hydrotalcite: synthetic hydrotalcite (Mg ₆ Al ₂ (CO ₃ ) (OH) i ₆ 4H 2 O, product number 652288) from Sigma-Aldrich, dried at 200 ° C. for 8 hours in a hot-air oven, water absorption capacity about 12% by weight

2- (3,4-epoxycyclohexyl) ethyltriethoxysilane (TEE): triethoxysilane with cycloaliphatic epoxide group, water uptake capacity (calculated as 3 moles of water per 1 mol of TEE) 19% by weight

Production of PSAs as First Transparent Adhesive

Table 1 lists two formulations of transparent first PSAs according to the invention (the amount of photoinitiator relates to the amount of epoxy resin used; the data are given in percent by weight based on the epoxy resin).

 Table 1

An activatable encapsulant PSA (T1) and a desiccant-filled PSA (T2) were prepared. The refractive index of the encapsulant PSA T2 without hydrotalcite was determined to be 1.53, that of hydrotalcite to 1.51.

The organics were dissolved at room temperature in a mixture of toluene (300 parts), acetone (150 parts) and petroleum spirit 60/95 (550 parts) to give a 50 wt% solution. Subsequently, the solution of the photoinitiator triarylsulfonium hexafluoroantimonate or the hydrotalcite was added.

Using a doctor blade method, the formulations were coated from solution onto a siliconized PET liner as a backing and dried at 120 ° C for 15 minutes. The thickness of the dried PSAs was 25 μm. The patterns were covered with another layer of a siliconized but more easily separating PET liner as a topcoat.

Preparation of adhesives as a second desiccant-filled adhesive

Table 2 lists three formulations for second compositions of the invention filled with dryers and three comparative adhesives. Both Adhesives according to the invention are two PSAs

(PSA1 and PSA2) as well as a desiccant-filled liquid adhesive (LA1). The amount of photoinitiator relates to the amount of epoxy resin used (the information is given in percent by weight based on the epoxy resin).

 Table 2

The preparation and drying of the desiccant-filled second adhesives was carried out in the case of the PSAs as described for the first transparent PSAs. The same applies to the comparative adhesives. The preparation of the liquid adhesive LA1 was carried out at room temperature by dispersing the Triarylsulfoniumhexa ^ fluoroantimonats and the calcium oxide in Uvacure. The photoinitiator-added activatable adhesives were cured with a UV-C dose of at least 400 mJ / cm ² by means of a medium pressure mercury radiator. The details of transparency, haze and breakthrough time in the present application, if curing takes place, always refer to the adhesive layer after curing. For the adhesives, the breakthrough time for various edge widths was determined (Table 3), in which case the entire surface of the adhesive layer 22 was made of the adhesive used, since only material parameters should be determined. The desiccant-filled liquid adhesive LA1 was applied here by adding a few monodisperse PMMA spheres in a thickness of 15 pm, the remaining adhesives in a thickness of 25 pm.

 The comparison of the non-transparent, highly desiccant-filled second adhesives (PSA1, PSA2, LA1) according to the prior art (V1, V2) or unfilled barrier adhesives (V3) clearly shows the superior barrier effect of the highly filled nontransparent adhesives adhesives.

Figure 3 shows the breakthrough time as a function of the water scavenger content (i.e., desiccant content, here CaO) for an edge width of 1 mm, with the entire area 22 of adhesives also being made analogous to the PSA2 adhesive (with varying desiccant content). It is striking that only from a desiccant content of 15 wt .-%, a technically exploitable breakthrough time is achieved. This is accompanied by a water absorption capacity of the second adhesive of more than 5 wt .-%.

Furthermore, the following constructions with a rim width AA of 2 mm were produced for the life test:

 Table 4

The desiccant-filled liquid adhesive layer LA1 was produced here (like all other adhesive layers also) in a thickness of 25 μm, the first adhesive acting as a spacer. Adhesive material squeezed out laterally was removed.

The respectively determined breakthrough times are shown in Table 4. These are, as expected, regularly below those for the full-surface coating with the desiccant-filled second adhesives, which is due to processing tolerances and errors. However, according to the invention, there are considerable advantages over the entire-area encapsulation with the transparent first adhesives. Accordingly, by increasing the proportion of calcium oxide by 50% in the second adhesive (PSA1 versus V1), the breakthrough time increases by about 100%, which also increases the synergistic effect above a T rockenmittelfüllgrads of

15% or a water absorption capacity of more than 5 wt% occupied.

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

Claims

claims A protection method for protecting an organic electronic device disposed on a substrate, comprising the steps  Attaching a cover over the organic electronic device such that the organic electronic device is at least partially covered; Adhering the cover to at least one layer of a first adhesive and at least one layer of a second adhesive,  characterized in that  the at least one layer of the first adhesive at least partially covers the organic electronic device and has a transparency of more than 80% and a haze of less than 5%;  and  - The at least one layer of the second adhesive comprising at least one layer of the first adhesive on its periphery, so that it forms a Randverkapselung, wherein the width of the edge encapsulation with the second adhesive is not more than two mm, and wherein the second adhesive has a water absorbency of more than 5% by weight. 2. Protection method according to claim 1, characterized in that the second adhesive has a water absorption capacity of more than 10 wt .-%, in particular more than 14 wt .-%, having. 3. Protection method according to claim 1 or 2, characterized in that the first adhesive contains a desiccant. 4. Protection method according to claim 3, characterized in that the difference in the refractive index between the first adhesive and desiccant is not more than 0.02. 5. Protection method according to claim 3 or 4, characterized in that the first adhesive contains a hydrotalcite and / or a molecularly dispersed desiccant. 6. Protection method according to one of claims 1 to 5, characterized in that the second adhesive contains a drying agent, in particular calcium oxide. 7. Protection method according to one of claims 1 to 6, characterized in that the first adhesive is applied in the form of an adhesive tape. 8. 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. Protection method according to one of claims 1 to 8, characterized in that the first and the second adhesive have the same base adhesive. 10. Protection method according to one of claims 1 to 9, characterized in that the second adhesive is applied spaced from the organic electronic device. 1 1. Organic electronic construction comprising  a substrate,  an organic electronic device arranged on the substrate,  a cover which at least partially covers the organic electronic device and which is adhesively bonded at least partially to the substrate and / or to the electronic device,  characterized in that the structure further comprises:  at least one layer of a first adhesive which at least partially covers the organic electronic device and has a transparency of more than 80% and a haze of less than 5%,  at least one layer of a second adhesive comprising the at least one layer of the first adhesive at its periphery so as to form an edge encapsulation, wherein the width of the edge encapsulation with the second adhesive is not more than two mm, and wherein the second adhesive is a Water absorption capacity of more than 5 wt .-% has. 12. Organic electronic structure according to claim 1 1, characterized in that the second adhesive has a water absorption capacity of more than 10 wt .-%, in particular more than 14 wt .-%, having. 13. Organic electronic structure according to claim 11 or 12, characterized in that the second adhesive contains a desiccant, in particular calcium oxide. 14. Organic electronic construction according to one of claims 11 to 13, characterized in that the first adhesive contains a desiccant 15. Organic electronic structure according to one of claims 11 to 14, characterized in that the first adhesive contains as desiccant hydrotalcite or a molecularly dispersed desiccant. 16. Organic electronic structure according to one of claims 11 to 15, characterized in that the first and the second adhesive have the same base adhesive. 17. Organic electronic construction according to one of claims 11 to 16, characterized in that the cover completely covers the electronic device. 18. An organic electronic structure according to any one of claims 11 to 17, characterized in that the layer of the second adhesive comprises the organic electronic arrangement completely. 19. Organic electronic structure according to one of claims 11 to 18, characterized in that the second adhesive is applied spaced from the organic electronic device.