EP2638570A1

EP2638570A1 - Adhesive compound and method for encapsulating an electronic assembly

Info

Publication number: EP2638570A1
Application number: EP11779147.5A
Authority: EP
Inventors: Alexander Steen; Thorsten Krawinkel; Klaus KEITE-TELGENBÜSCHER; Judith Grünauer; Jan Ellinger
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2010-11-12
Filing date: 2011-10-27
Publication date: 2013-09-18
Also published as: DE102010043871A1; KR20130141588A; WO2012062587A1; CN103348465A; CN103348465B; TW201241125A

Abstract

The invention relates to the use of an adhesive compound for encapsulating an (opto-)electronic application, containing an organometallically modified polymer created by reacting an elastomer with an organometallic compound, wherein the central atom of the organometallic compound is a metal or metalloid of the 3rd and 4th main groups or 3rd and 4th subgroups.

Description

tesa Societas Europaea

Hamburg

description

Adhesive composition and method for encapsulating an electronic device The present invention relates to an adhesive composition for the encapsulation of an electronic device and to a method for its use.

(Opto) electronic arrangements are increasingly used in commercial products or are about to be launched. 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 takes place, for example, by printing processes such as high-pressure, intaglio, screen printing, flat printing or as well as so-called "non-impact printing" such as thermal transfer printing, inkjet printing or digital printing, but in many cases vacuum processes such as chemical vapor deposition (CVD), physical vapor Deposition (PVD), plasma-enhanced chemical or physical deposition methods (PECVD), sputtering, (plasma) etching or vapor deposition used, the structuring is usually done by masks.

Electrophoretic or electrochromic structures or displays, organic or polymeric light-emitting diodes (OLEDs or PLEDs) in display and display devices or as illumination, electroluminescent lamps, light-emitting electrochemical devices may be mentioned as examples of (commercial) electronic applications which are already interesting in their market potential 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 organic or inorganic-based RFID transponder listed. 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 permeants. Permeants can be a variety of low molecular weight organic or inorganic compounds, especially water vapor and oxygen.

A variety of (opto) electronic arrangements in the field of inorganic and / or organic (opto) electronics, especially when using organic raw materials, is sensitive to both water vapor and oxygen, for many arrangements, the penetration of water or Water vapor 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 reduce.

In inorganic and / or organic (opto) electronics, in particular in organic (opto) electronics, there is a particular need for flexible adhesive solutions which represent a permeation barrier for permeants such as oxygen and / or water vapor. In addition, there are a variety of other requirements for such (opto) -electronic devices. The flexible adhesive solutions should therefore not only achieve good adhesion between two substrates, but additionally meet properties such as high shear strength and peel strength, chemical resistance, aging resistance, high transparency, easy processability and high flexibility and flexibility.

A common approach in the art is therefore to allow the electronic assembly between two water vapor and oxygen impermeable substrates lay. This is followed by a seal at the edges. For inflexible structures, glass or metal substrates are used which offer a high permeation barrier but are very susceptible to mechanical stress. Furthermore, these substrates cause a relatively large thickness of the entire assembly. In the case of metal substrates, there is also no transparency. For flexible arrangements, however, surface substrates such as transparent or non-transparent films are used, which can be designed in multiple layers. Here, both combinations of different polymers, as well as inorganic or organic layers can be used. The use of such surface substrates allows a flexible, extremely thin structure. A wide variety of substrates such as films, fabrics, nonwovens and papers or combinations thereof are possible for the various applications.

In order to achieve the best possible sealing, special barrier adhesives are used. A good adhesive for the sealing of (opto) electronic components has a low permeability to oxygen and in particular to water vapor, has sufficient adhesion to the assembly and can flow well on this. Low adhesion to the assembly reduces the barrier effect at the interface, allowing oxygen and water vapor to enter regardless of the properties of the adhesive. Only if the contact between mass and substrate is continuous, the mass properties are the determining factor for the barrier effect of the adhesive.

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 specified. 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 permeant under steady state conditions at a given 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 describes predominantly the affinity of the barrier adhesive to the permeant. 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 permeant in the barrier material and is directly dependent on properties such as molecular mobility or free volume. Often relatively low values are achieved for strongly cross-linked or highly crystalline D materials. 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-0 bond (large diffusion term). For a good barrier effect therefore requires a good balance between the solubility term S and the diffusion term D.

For this purpose, above all, liquid adhesives and adhesives based on epoxides have been used (WO 98/21287 A1, US 4,051,195 A, US 4,552,604 A). These have a low diffusion term D due to strong cross-linking. Their main application is edge bonding of rigid arrangements, but also moderately flexible arrangements. Curing takes place thermally or by means of UV radiation. A full-surface bonding is hardly possible due to the shrinkage caused by the curing, since it comes to tensions between adhesive and substrate during curing, which in turn can lead to delamination.

The use of these liquid adhesives has a number of disadvantages. For example, low-molecular-weight components (VOCs) can damage the delicate electronic structures of the device and make it difficult to handle production. The adhesive must be applied consuming each individual component of the arrangement. The purchase of expensive dispensers and fixators is necessary to ensure accurate positioning. The type of application also prevents a rapid continuous process and also by the subsequently required lamination step, the achievement of a defined layer thickness and bond width can be made difficult within narrow limits by the low viscosity.

Furthermore, such highly crosslinked adhesives have only a low degree of flexibility after curing. The use of thermal-crosslinking systems is limited in the low temperature range or in 2-component systems by the pot life, ie the processing time until a gelling has taken place. In the high temperature range and in particular with long reaction times, in turn, the sensitive (opto) electronic structures limit the usability of such systems - the maximum applicable temperatures in (opto) electronic structures are sometimes only at 60 ° C, since a pre-damage already occurs from this temperature can. In particular, flexible arrangements which contain organic electronics and are encapsulated with transparent polymer films or composites of polymer films and inorganic layers have narrow limits here. This also applies to laminating under high pressure. To achieve improved durability is here a waiver of a temperature-stressing step and a lamination under a lower pressure of advantage.

As an alternative to the thermally curable liquid adhesives, radiation-curing adhesives are also frequently used in the meantime (US 2004/0225025 A1). The use of radiation-curing adhesives avoids a long-lasting heat load on the electronic device. However, the irradiation leads to a short-term, selective heating of the arrangement since, in addition to UV radiation, as a rule a very high proportion of IR radiation is also emitted. Other above-mentioned disadvantages of liquid adhesives such as VOC, shrinkage, delamination and low flexibility also remain. Problems can arise from additional volatile constituents or by-products from the photoinitiators or sensitizers. In addition, the arrangement must be permeable to UV light. Since components, in particular organic electronics and many of the polymers used are often sensitive to UV exposure, a longer-lasting outdoor use is not possible without further additional protective measures, such as other cover films. In the case of UV-curing adhesive systems, these can only be applied after the UV curing, which additionally increases the complexity of the production and the thickness of the arrangement.

US 2006/0100299 A1 discloses a UV-curable pressure-sensitive adhesive tape for encapsulating an electronic device. The pressure-sensitive adhesive tape comprises an adhesive based on a combination of a polymer having a softening point greater than 60 ° C., a polymerizable epoxy resin having a softening point of below 30 ° C. and a photoinitiator. The polymers may be polyurethane, polyisobutylene, polyacrylonitrile, polyvinylidene chloride, poly (meth) acrylate or polyester, but especially an acrylate. Furthermore, adhesive resins, plasticizers or fillers are included.

Acrylic compounds have a very good resistance to UV radiation and various chemicals, but have very different bond strengths on different substrates. While the bond strength on polar substrates such as glass or metal is very high, the bond strength on nonpolar substrates such as polyethylene or polypropylene is rather low. Here there is a danger of diffusion at the Interface in particular. In addition, these masses are very polar, which favors a diffusion of water vapor in particular, despite subsequent networking. The use of polymerisable epoxy resins further strengthens this tendency. Pressure-sensitive adhesive tapes generally require a certain amount of time, sufficient pressure and a good balance between the viscous component and the elastic component as a result of the relatively high molecular weight polymers, in contrast to liquid adhesives, for good wetting and adhesion to the surface. WO 2007/087281 A1 discloses a transparent flexible pressure-sensitive adhesive tape based on polyisobutylene (PIB) for electronic applications, in particular OLED. In this case, polyisobutylene having a molecular weight of more than 500,000 g / mol and a hydrogenated cyclic resin is used. Optionally, the use of a photopolymerizable resin and a photoinitiator is possible.

Adhesives based on polyisobutylene have a good barrier to water vapor due to their low polarity, but have a relatively low cohesiveness even at high molecular weights, which is why they often have a low shear strength at elevated temperatures. The proportion of low molecular weight components can not be reduced arbitrarily, otherwise the adhesion is significantly reduced and the interfacial permeation increases. When using a high proportion of functional resins, which is necessary due to the very low cohesion of the mass, the polarity of the mass is increased again and thus increases the solubility term.

Described are further barrier adhesives based on styrene block copolymers and hydrogenated as possible resins (see DE 10 2008 047 964 A1).

The formation of at least two domains within the block copolymer additionally gives a very good cohesion at room temperature and at the same time improved barrier properties.

One way to improve the barrier effect is the use of substances that react with water or oxygen. In the (opto) electronic arrangement penetrating oxygen or water vapor is then to these substances chemically or physically, preferably chemically bound. These substances are referred to in the literature as "getters", "scavenger", "desiccants" or "absorbers". In the following, only the term getter will be used. As such getters are described in adhesives mainly inorganic fillers such as calcium chloride or various oxides. Since these are not soluble in the adhesive, they have the disadvantage that the adhesive loses its transparency and adhesion at appropriate levels. Therefore, organic getters or hybrids that are soluble in the adhesive are more suitable, but they must not migrate out of the adhesive. These additives do not change the diffusion values, but only the breakthrough time, the substances are saturated with water or oxygen or consumed in a chemical reaction with water or oxygen, they have no effect, the diffusion is then only the adhesive without getter. Nevertheless, these getters can increase the lifetime of the (opto) electronic components.

Examples of the use of getters in liquid adhesive systems for encapsulating (opto) electronic structures are given, for example, in US Pat. No. 6,833,668 B1, JP 2000 31 1 782 A and EP 1 037 192 A2. A PSA is also known from the prior art (WO 03/065470 A1), which is used in an electronic structure as a transfer adhesive. The adhesive contains an inorganic functional filler that reacts with oxygen or water vapor within the assembly. For a simple application of a getter within the structure is possible. To seal the exterior structure, another low permeability adhesive is used.

A similar pressure-sensitive adhesive is used in JP 2004 296 381 A. Again, only inorganic getters are used. Further getter PSAs are known from US 5,591, 379 A and US 5,304,419 A, but these are not used to encapsulate an electronic structure, but placed within the structure. The object of the present invention is to provide an adhesive for the encapsulation of an electronic device against permeants, especially water vapor, which is transparent, which provides a good barrier to water vapor, the elastomer can react with water, whereby the breakthrough time of water in particular is increased , which increases the breakthrough time, in particular of water, and with the same time a good encapsulation can be achieved. Furthermore, the life of (opto) electronic arrangements should be increased by the use of a suitable, in particular flexible, adhesive. This object is achieved by using an adhesive as laid down in the main claim. The subject of the dependent claims are advantageous developments of the adhesive and an encapsulated with the adhesive electronic device.

Accordingly, the invention relates to the use of an adhesive comprising an organometallic modified polymer formed by reaction of an elastomer with an organometallic compound, wherein the central atom of the organometallic compound is a metal or semimetal of the 3rd and 4th main group or the 3rd and 4th subgroup. The modified polymer is capable of reacting with moisture.

In this case, the organometallic compound can be introduced both by a reaction via a functional group in the polymer, as well as by a radical reaction with a double bond present in the polymer chain.

A reactive group may be, for example, an epoxy or anhydride group, but also an amino group is conceivable. This group can then react with a corresponding group in the organometallic compounds to form a polymer with organometallic modification. In the case of an epoxy or anhydride group, for example, this can react with an amino group in the organometallic compound. For this purpose, for example, organometallic compounds of the general formula ¹ ) m With

M = Si, Sn, Pb, Ti, Zr

R ¹ , R ^{2 are} independently selected from the group methyl, ethyl,

2-methoxyethyl, i-propyl, butyl

m = 1 to 3

n = 1 to 12

P = 1 or 2

and

for p = 1

Y = a functional group selected from the group

Glycidyl, glycidyloxy, isocyanato, -NH-CH 2 -CH 2 -NR ₄ R ₅ , -NR ₄ R ₅ (with R ₄ and R ₅ independently selected from the group H, alkyl, phenyl, benzyl, cyclopentyl, cyclohexyl), SH

or

for p = 2

Y = NH can be used.

Silanes and titanates with an amino or sulfide group are particularly preferred.

The reaction with the polymers can be done spontaneously in solution or can be accelerated by heating and adding catalysts such as acids. Ideally, the reaction is spontaneous, so that all components of the adhesive, in addition to the polymers and organometallic compounds, the tackifiers, plasticizers and other auxiliaries, can be brought into solution simultaneously, and the reaction takes place during the dissolution of the individual components. An attachment of an organometallic compound of the present invention can also be introduced via double bonds in the polymer, if the organometallic compound also contains at least one double bond.

This reaction usually takes place radically, with a radical starter at elevated temperatures. Since the organometallic compounds are sensitive to water, anhydrous solvents should be used. In this case, organometallic compounds with vinyl, acrylic or methacrylic groups can be used.

For example, organometallic compounds of the following form may be included:

(OR ¹ ) _m

CH ₂ = C - C - O ^ - (CH ₂ ) _n M (R ² ) _3-m

R ³ O

With

M = Si, Sn, Pb, Ti, Zr

R ¹ , R ² = independently selected from the group methyl, ethyl,

2-methoxyethyl, i-propyl, butyl

R ³ = H or CH ₃

m = 1 to 3

n = 1 to 12

x = 0 or 1

Polymers in which a silane group has been introduced via this route have been known for some time, for example from EP 0 827 994 A1, but application as barrier adhesives has not been described. If the polymers contain double bonds to which the organometallic compounds are to be linked via a free-radical reaction, it is advantageous if the number of double bonds is not too high, so that crosslinking of the polymers does not take place during the free-radical reaction. It is therefore preferred to use partially hydrogenated polymers. The same applies if the double bonds of the polymers are converted into epoxides only by a reaction with, for example, peracids.

Polymers with double bonds for modification can be, for example, polymers with butadiene or isoprene monomers, such as polybutadiene, polyisoprene, styrene-butadiene rubbers, block copolymers of vinylaromatics and isoprene or butadiene, as described in more detail below, block copolymers of isoprene and butadiene, nitrile rubber, ABS or similar. Polymers of ethylene-propylene with another monomer having two double bonds, for example EPDM, can also be used.

Polymers having reactive groups to which organometallic compounds can be attached are, for example, systems containing epoxide or anhydride groups. As polymers are used, for example, the following.

Polymers containing epoxide groups are preferably prepared by reacting peroxides or peroxycarboxylic acids with double bonds still present in the main chain of the unmodified polymer. Polymers with terminal epoxide groups are not preferred because they are usually low molecular weight and have only two epoxide groups, therefore, not enough organometallic groups can be attached.

Epoxidizable polymers having a double bond may be those described above.

Acid anhydride-containing polymers according to the invention can be used both those which have been prepared by modification of finished polymers with, for example, maleic anhydride under free-radical conditions, as well as those which have incorporated anhydride-containing monomers in the main or side chain. In the case of the modified polymers, a number of polyolefins, such as polyethylene or polypropylene, but also poly-α-olefins, polymerized from ethylene and at least one other α-olefin, polybutenes, as well as block copolymers of ethylene and propylene can be used. Also, block copolymers of a vinyl aromatic and a diene are useful, especially when the majority of the remaining double bonds is hydrogenated. In all these polymers, the content of double bonds is preferably very low, since it is in the reaction of the polymers with Otherwise, the acid anhydrides can easily lead to undesirable crosslinking reactions.

Preference is given here to block copolymers comprising polymer blocks predominantly formed of vinylaromatics (A blocks), preferably styrene, and those predominantly formed by polymerization of 1,3-dienes (B blocks), preferably butadiene, isoprene or a mixture of both monomers. These B blocks usually have a low polarity. Both homo- and copolymer blocks are preferably usable as B blocks. Block copolymers with polyisobutylene in the main chain can also be used.

The block copolymers resulting from the A and B blocks may contain the same or different B blocks, which may be partially, selectively or preferably fully hydrogenated. The block copolymers may have linear A-B-A structures. It is also possible to use block copolymers of radial form as well as star-shaped and linear multiblock copolymers. As further components, A-B diblock copolymers may be present. All of the aforementioned polymers can be used alone or in admixture with each other. It is also possible to use block copolymers which, in addition to the above-described blocks A and B, contain at least one further block, for example A-B-C block copolymers.

It is also conceivable to use the abovementioned B blocks with A blocks of another chemical nature, which exhibit a glass transition temperature above room temperature, such as, for example, polymethyl methacrylate.

In an advantageous embodiment, the block copolymers have a Polyvinylaromatenanteil of 10 wt .-% to 35 wt .-%.

For the preparation of a pressure-sensitive adhesive, the proportion of vinylaromatic block copolymers in total, based on the total pressure-sensitive adhesive mass, is preferably at least 30% by weight, preferably at least 40% by weight, more preferably at least 45% by weight. Too low a proportion of vinylaromatic block copolymers has the consequence that the cohesion of the PSA is relatively low. The maximum proportion of the vinylaromatic block copolymers in total, based on the total PSA, is at most 80% by weight, preferably at most 70% by weight. Too high a proportion of vinylaromatic block copolymers, in turn, has the consequence that the PSA is barely tacky.

At least part of the block copolymers used is acid-anhydride-modified or epoxidized or still has double bonds.

The anhydride modification is carried out mainly by free-radical graft copolymerization of unsaturated acid anhydrides, such as maleic anhydride, citraconic anhydride, dimethylmaleic anhydride, ethyl and diethylmaleic anhydride, chloro and dichloromaleic anhydride,

Phenylmaleic anhydride, itaconic anhydride, methylitaconic anhydride, aconitic anhydride, nadic anhydride, methylnadic anhydride,

Tetrahydrophthalic anhydride or methyltetrahydrophthalic anhydride, preferably maleic anhydride. The proportion of acid or acid anhydride is preferably between 0.5 and 4 percent by weight based on the total block copolymer.

The epoxide modification takes place by reaction with peracids of block copolymers still containing double bonds.

The most commonly used epoxidizing agents are hydrogen peroxide with different catalysts, tert-butyl hydroperoxide, meta-chloroperbenzoic acid (MCPBA), or peroxy-ante- or peroxyacetic acid, which are prepared in situ.

Polymers in which the acid anhydride is incorporated directly into the polymer chain are, for example, polymers of styrene and maleic anhydride, mostly alternating, such as SMA polymers from Sartomer, polymers of ethylene and maleic anhydride, such as Gantrez polymers of the company ISP or isobutylene and maleic anhydride, such as Isobam Kuraray, just to name a few Preferably, the adhesive is a pressure-sensitive adhesive, so a viscoelastic composition which remains permanently tacky and tacky at room temperature in a dry state. The bonding takes place by light pressure immediately on almost all substrates.

The adhesive may also be a hotmelt adhesive, ie a water-free and solvent-free adhesive which is solid at room temperature and which is applied to the parts to be bonded from the melt and physically sets after consolidation on cooling to solidify.

In order to obtain melt or PSAs from the organometallic modified polymers according to the invention, tackifiers are preferably used. Adhesive resins which are compatible with the silane-modified polymer and with the soft blocks in the vinylaromatic block copolymers serve this purpose.

Suitable tackifier resins include, but are not limited to, non-hydrogenated, partially or fully hydrogenated rosin and rosin derivative resins, hydrogenated polymers of dicyclopentadiene, non-hydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C ₅ , C ₅ / C ₉ . or C ₉ - Monomerströmen, polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene, hydrogenated polymers of preferably pure C ₈ - and C ₉ aromatics. The aforementioned adhesive resins can be used both alone and in admixture. Both solid and liquid resins can be used at room temperature.

In order to ensure high aging and UV stability, hydrogenated resins having a degree of hydrogenation of at least 90%, preferably of at least 95%, are preferred.

Furthermore, non-polar resins with a DACP value (diacetone alcohol cloud point) above 30 ° C. and a MMAP value (mixed methylcyclohexane aniline point) of greater than 50 ° C., in particular with a DACP value above 37 ° C. and a MMAP value greater than 60 ° C preferred. The DACP value and the MMAP value each indicate the solubility in a particular solvent. By selecting these areas, a particularly high permeation barrier, in particular against water vapor, is achieved.

Resins having a softening point (ring / ball, determination according to DIN EN ISO 4625) of more than 95 ° C., in particular more than 100 ° C., are also preferred. Through this Selection a particularly high permeation barrier, especially against oxygen, achieved.

The softening point is the temperature (or the temperature range) at which glasses, amorphous or partially crystalline polymers change from the glassy, hard-elastic to a soft state. The reduction in the hardness of corresponding substances at the softening point is made clear, for example, by the fact that a body applied to a substance sample under load is pressed into it when the softening point is reached. The softening point is always above the glass transition temperature, but in most polymers, well below the temperature at which they are completely in the liquid state.

If an increase in the bond strength is to be achieved, however, preference is given in particular to resins having a softening temperature below 95.degree. C., in particular below 90.degree.

According to a preferred embodiment, the adhesive contains tackifiers, preferably to a proportion of up to 60 wt .-% based on the total amount. In the case of a hot melt adhesive, the proportion may be lower, for example up to 30 wt .-% based on the total amount.

As further additives can typically be used:

Plasticizers such as plasticizer oils or low molecular weight liquid polymers such as low molecular weight polybutenes

· Primary antioxidants such as sterically hindered phenols

• secondary antioxidants such as phosphites or thioethers

• Process stabilizers such as C radical scavenger

• Sunscreens such as UV absorbers or hindered amines

• processing aids

· Endblocker starch resins as well

Optionally further polymers of preferably elastomeric nature; suitably usable elastomers include, but are not limited to, those based on pure hydrocarbons, for example, unsaturated polydienes such as natural or synthetically produced polyisoprene or polybutadiene, chemically substantially saturated elastomers such as saturated ethylene-propylene copolymers, α-olefin copolymers, polyisobutylene, butyl rubber, ethylene-propylene rubber, and chemically functionalized hydrocarbons such as halogen-containing, acrylate-containing, allyl or vinyl ether-containing polyolefins.

It should be noted that the adhesive according to the invention is also suitable without the resins and / or additives listed depending on the application, be it that the resins and / or additives are omitted in their entirety, in any combination or individually.

In particular, the adhesive according to the invention omits inorganic silicates and aluminosilicates.

The direct attachment of an organometallic compound, which reacts with water, to the polymer has succeeded in integrating a getter into the polymer.

The present invention is based initially on the finding that, despite the disadvantages described above, it is nevertheless possible to use a melt or pressure-sensitive adhesive for encapsulating an electronic arrangement in which the disadvantages described above with regard to PSAs do not occur or only diminish. It has been found that enamel or PSAs which contain a getter covalently bound to the polymer are particularly well suited for the encapsulation of electronic components since, on the one hand, there is no risk of an organic (fluid) getter entering the electronic system migrated active components and leads there to damage and on the other hand, the occurring during the use of particulate getter adhesive reduction and resulting turbidity of the adhesive is avoided.

In the field of adhesives, PSAs are characterized in particular by their permanent tackiness and flexibility. A material that exhibits permanent tack must have a suitable combination of adhesive and cohesive properties at all times. This characteristic distinguishes the pressure-sensitive adhesives, for example, from reactive adhesives which hardly provide cohesion in the unreacted state. For good adhesion properties, To adjust pressure-sensitive adhesives so that an optimal balance of adhesive and cohesive properties exists.

In the present case, encapsulation is not only a complete enclosure with said PSA, but also a partial application of the PSA to the areas of the (opto) electronic device to be encapsulated, for example a one-sided overlap or a framing of an electronic structure. By selecting the constituents of the PSA and the resulting low polarity and the resulting low solubility term (S) of the diffusion coefficient, a low permeability of permeants such as water vapor and oxygen is achieved, but in particular of water vapor. The incorporated silane continues to increase the breakthrough time.

The advantage of the present invention is thus compared to other PSAs, the combination of very good barrier properties to oxygen and especially to water vapor with good interfacial adhesion to different substrates, good cohesive properties, compared to liquid adhesives, a very high flexibility and a simple application in the (opto) electronic arrangement and with / in the encapsulation. Furthermore, in certain embodiments, there are also transparent adhesives that can be used in a special way for use in (opto) electronic arrangements, since a reduction of incident or emerging light is kept very low.

Such a PSA can be easily integrated into an electronic device, especially in such an arrangement that requires high flexibility. Further particularly advantageous properties of the pressure-sensitive adhesive are similarly good adhesion to different substrates, high shear strength and high flexibility. By a very good adhesion to the substrate also a small Grenzflächenpermeation is achieved. By using the formulations described herein for the encapsulation of (opto) electronic structures advantageous arrangements are obtained, which combine the advantages mentioned above, the Accelerate and simplify the encapsulation process and increase product quality.

Since in certain embodiments of the PSA no further thermal process steps or irradiation are necessary, no shrinkage occurs by a crosslinking reaction carried out after the application in the construction of the (opto) electronic structure and the PSA is present as a web-shaped material or in a form adapted to the electronic arrangement , the mass can be easily and quickly integrated under low pressure in the encapsulation process of the (opto) - electronic structure. The disadvantages usually associated with the avoided processing steps, such as thermal and mechanical stresses, can thus be minimized. Encapsulation by lamination of at least parts of the (opto) electronic structures with a flat barrier material (for example glass, especially thin glass, metal oxide coated films, metal foils, multilayer substrate materials) is possible with very good barrier effect in a simple roll-to-roll process , The flexibility of the entire structure depends, in addition to the flexibility of the PSA, on other factors such as geometry and thickness of the (opto) electronic structures or the surface barrier materials. The high flexibility of the PSA, however, makes it possible to realize very thin, flexible and flexible (opto) electronic structures. By the term "flexible" is meant the property of following the curvature of a curved article such as a drum of certain radius, in particular a radius of 1 mm, without damage. It is of particular advantage for the encapsulation of (opto) electronic structures if the PSA according to the invention is heated during or after the application. As a result, the PSA can flow better and thus the permeation at the interface between the (opto) electronic device and the PSA can be reduced. The temperature should preferably be more than 30 ° C., more preferably more than 50 ° C., in order to promote the flow accordingly. However, the temperature should not be selected too high in order not to damage the (opto) electronic arrangement. When using a hotmelt adhesive must be laminated at elevated temperatures in any case, so that the adhesive is tacky and can flow onto the substrate. In a preferred embodiment of a method for encapsulating an (opto) electronic device against permeants, the PSA may be provided in the form of an adhesive tape. This mode of administration allows a particularly simple and uniform application of the PSA.

In one embodiment, the general term "adhesive tape" encompasses a carrier material which is provided on one or both sides with a pressure-sensitive adhesive The carrier material comprises all planar structures, for example films or film sections expanded in two dimensions, belts of extended length and limited width, belt sections , Diecuts, multi-layer arrangements and the like.

The tape can be provided in fixed lengths such as by the meter or as an endless product on rolls (Archimedean spiral). As support, it is possible to use all known supports, for example scrims, woven fabrics, knitted fabrics, nonwovens, films, papers, tissues, foams and foamed films. In the present case, preference is given to using polymer films, film composites or films or film composites provided with organic and / or inorganic layers. Such films / film composites can consist of all common plastics used for film production, but are not to be mentioned as examples by way of non-limiting example:

Polyethylene, polypropylene - especially the oriented polypropylene (OPP) produced by mono- or biaxial stretching, cyclic olefin copolymers (COC), polyvinyl chloride (PVC), polyesters - in particular polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polycarbonate (PC), polyamide (PA), polyethersulfone (PES) or polyimide (PI).

In particular, crosslinked polyethylene foams or viscoelastic supports are suitable. The latter are preferably made of polyacrylate, more preferably filled with hollow bodies of glass or polymers. The backings may be prepared by priming or physical pretreatment such as corona or etching prior to contacting with the adhesive.

The carrier may also be multi-layered, for example by laminating different layers together or coextruding layers. The support may also be combined with organic or inorganic coatings or layers. This can be done by conventional methods such as painting, printing, evaporation, sputtering, co-extrusion or lamination. By way of example, but not by way of limitation, mention may be made here of oxides or nitrides of silicon and aluminum, indium-tin oxide (ITO) or sol-gel coatings.

These films / film composites, in particular the polymer films, are particularly preferably provided with a permeation barrier for oxygen and water vapor, the permeation barrier exceeding the requirements for the packaging area (WVTR <10 ^"1 g / (m ² d); OTR <10 ^{" 1} cm ³ / (m ² d bar)). The determination of the permeability to oxygen (OTR) and water vapor (WVTR) is carried out according to DIN 53380 Part 3 or ASTM F-1249. The oxygen permeability is measured at 23 ° C and a relative humidity of 50%. The water vapor permeability is determined at 37.5 ° C and a relative humidity of 90%. The results are normalized to a film thickness of 50 μηι.

In addition, in a preferred embodiment, the films / film composites may be made transparent, so that the overall structure of such an adhesive article is transparent. "Transparency" means an average transmission in the visible range of light of at least 75%, preferably higher than 90%.

Furthermore, the term "adhesive tape" also includes so-called "transfer tapes", that is, an adhesive tape without a carrier. In the case of a transfer adhesive tape, the adhesive is applied before application between flexible liners which are provided with a release layer and / or have anti-adhesive properties. For application, a liner is first removed, the adhesive is applied and then the second liner is removed. The PSA can thus be used directly for the connection of two surfaces in (opto) electronic arrangements.

More preferably, a pressure-sensitive adhesive is used, which is transparent in certain embodiments in the visible light of the spectrum (wavelength range of about 400 nm to 800 nm). For certain applications, such as solar cells, this range can also be extended to defined UV or IR regions. The desired transparency in the preferred range of the visible spectrum can be achieved in particular by the use of colorless adhesive resins. Such a pressure-sensitive adhesive is thus also suitable for full-surface use over an (opto) electronic structure. A full-surface bonding offers, with an approximately central arrangement of the electronic structure in relation to an edge seal, the advantage that the permeant would have to diffuse through the entire surface before it reaches the structure. The permeation path is thus significantly increased. The permeation paths extended in this embodiment compared to edge sealing, such as liquid adhesives, have a positive effect on the overall barrier, since the permeation path is inversely proportional to the permeability.

In this case, "transparency" means an average transmission of the adhesive in the visible range of light of at least 75%, preferably higher than 90% When used as a pressure-sensitive adhesive tape with carrier, the maximum transmission of the entire assembly also depends on the type of carrier used and on the carrier Type of construction.

The electronic structures of (opto) electronic devices are often susceptible to UV radiation. It has therefore turned out to be particularly advantageous if the PSA is also UV-blocking. In the present case, the term "UV-blocking" denotes an average transmittance of not more than 20%, preferably not more than 10%, more preferably not more than 1% in the corresponding wavelength range. UVA radiation) formed UV blocking, preferably in the wavelength range of 280 nm to 400 nm (UVA and UVB radiation), more preferably in the wavelength range of 190 nm to 400 nm (UVA, UVB and UVC radiation).

The UV-blocking effect of the PSA can be achieved in particular by adding UV blockers or suitable fillers to the PSA. Suitable UV blockers are, for example, HALS (Hinder Armine Light Stabilizer) such as Tinuvin from BASF or benzimidazole derivatives. Particularly suitable as the filler is titanium dioxide, in particular nanoscale titanium dioxide, since this allows transparency to be maintained in the visible range. In a further advantageous embodiment, the PSA shows a very good resistance to weathering and UV light. This resistance can be achieved in particular by using hydrogenated elastomers and / or hydrogenated resins.

The preparation and processing of the PSA can be carried out from solution, dispersion and from the melt. Preferably, the preparation and processing takes place from solution or from the melt. Particularly preferred is the production of the adhesive from solution. In this case, the components of the PSA are dissolved in a suitable solvent, for example toluene or mixtures of gasoline and acetone, and applied to the carrier by generally known methods. In melt processing, these may be application methods via a die or calender. In solution processes, coatings with doctor blades, knives, rollers or nozzles are known, to name but a few.

In a preferred embodiment, the PSA contains no longer volatile organic compounds (VOC) than 50 μg carbon per gram mass, in particular not more than 10 μg C / g, measured according to VDA 277. This has the advantage of better compatibility with the organic materials of the electronic Structure as well as possibly existing functional layers, such as a transparent conductive metal oxide layer such as indium tin oxide or such a layer of intrinsically conductive polymer.

The PSA can either be used for full-surface bonding of (opto) -electronic arrangements or, after suitable fabrication, diecuts, rolls or other shaped articles can be produced from the PSA or the PSA tape. Corresponding diecuts and shaped bodies of the PSA / of the pressure-sensitive adhesive tape are then preferably adhesively bonded to the substrate to be bonded, for example as borders or delimitation of an (opto) electronic arrangement. The choice of the shape of the stamped product or the molding is not limited and is chosen depending on the type of (opto) electronic arrangement. The possibility of laminar lamination, in comparison to liquid adhesives, by increasing the permeation path length through lateral penetration of the permeants, is beneficial to the mass barrier properties since the permeation path length is inversely proportional to permeation. If the PSA is provided in the form of a planar structure with a carrier, it is preferred that the thickness of the carrier is in the range from about 1 μηι to about 350 μηι, more preferably between about 4 μηι and about 250 μηι and particularly preferably between about 12 μηι and about 150 μηι. The optimum thickness depends on the (opto) electronic arrangement, the end use and the type of execution of the PSA. Very thin carriers in the range of 1 to 12 μηι are used in (opto) electronic structures that should achieve a low overall thickness, but it is the cost of integration into the structure increases. Very thick carriers between 150 and 350 μm are used when an increased permeation barrier through the carrier and the rigidity of the structure are in the foreground; the protective effect is increased by the carrier, while the flexibility of the structure is reduced. The preferred range between 12 and 150 μηι represents an optimal compromise as encapsulation solution for most (opto) electronic structures.

Further details, objects, features and advantages of the present invention will be explained in more detail below with reference to preferred embodiments. Show it

1 shows a first (opto) electronic arrangement in a schematic representation,

2 shows a second (opto) electronic arrangement in a schematic representation,

Fig. 3 shows a third (opto) electronic arrangement in a schematic representation.

1 shows a first embodiment of an (opto) electronic arrangement 1. This arrangement 1 has a substrate 2 on which an electronic structure 3 is arranged. The substrate 2 itself is formed as a barrier for permeants and thus forms part of the encapsulation of the electronic structure 3. Above the electronic structure 3, in the present case also spatially spaced therefrom, another cover 4 designed as a barrier is arranged. In order to encapsulate the electronic structure 3 also to the side and at the same time to connect the cover 4 with the electronic device 1, a pressure-sensitive adhesive 5 is provided circumferentially next to the electronic structure 3 on the substrate 2. The pressure-sensitive adhesive 5 connects the cover 4 to the substrate 2. The pressure-sensitive adhesive 5 also allows the spacing of the cover 4 from the electronic structure 3 by means of a correspondingly thick embodiment.

The PSA 5 is one based on organometallic modified polymers, as described above in a general form and is set forth in more detail below in exemplary embodiments. In the present case, the PSA 5 not only performs the function of bonding the substrate 2 to the cover 4, but also provides a barrier layer for permeants so as to encapsulate the electronic structure 2 from the side against permeants such as water vapor and oxygen.

The PSA 5 is presently also provided in the form of a diecut from a double-sided adhesive tape. Such a punched product enables a particularly simple application. Fig. 2 shows an alternative embodiment of an (opto) electronic device 1. Shown again is an electronic structure 3, which is arranged on a substrate 2 and encapsulated by the substrate 2 from below. Above and to the side of the electronic structure, the pressure-sensitive adhesive 5 is now arranged over its entire surface. The electronic structure 3 is thus encapsulated by the pressure-sensitive adhesive 5 at these points. On the PSA 5, a cover 4 is then applied. In contrast to the previous embodiment, this cover 4 does not necessarily have to meet the high barrier requirements, since the barrier is already provided by the pressure-sensitive adhesive. The cover 4 may, for example, only perform a mechanical protective function, but it may also be additionally provided as a permeation barrier.

FIG. 3 shows a further alternative embodiment of an (opto) electronic arrangement 1. In contrast to the previous embodiments, two pressure-sensitive adhesives 5a, b are now provided, which in the present case are of identical design. The first pressure-sensitive adhesive 5a is arranged over the entire surface of the substrate 2. On the PSA 5a is then the provided electronic structure 3, which is fixed by the pressure-sensitive adhesive 5a. The composite of PSA 5a and electronic structure 3 is then completely covered with the further PSA 5b, so that the electronic structure 3 is encapsulated on all sides by the PSAs 5a, b. Above the PSA 5b, the cover 4 is again provided.

In this embodiment, therefore, neither the substrate 2 nor the cover 4 necessarily have barrier properties. However, they can nevertheless be provided to further restrict the permeation of permeants to the electronic structure 3.

With particular reference to FIGS. 2, 3, it is pointed out that these are schematic representations. In particular, it can not be seen from the illustrations that the pressure-sensitive adhesive 5 is here and preferably applied in each case with a homogeneous layer thickness. At the transition to the electronic structure, therefore, no sharp edge forms, as it appears in the illustration, but the transition is fluid and it may remain small un-filled or gas-filled areas. Optionally, however, can also be adapted to the substrate, especially if the application is carried out under vacuum. In addition, the PSA is locally compressed to different degrees, so that by flow processes a certain compensation of the height difference can be made to the edge structures. The dimensions shown are not to scale, but rather serve only a better representation. In particular, the electronic structure itself is usually relatively flat (often less than 1 μηι thick). The application of the PSA 5 takes place in all embodiments shown in the form of a pressure-sensitive adhesive tape. This can basically be a double-sided pressure-sensitive adhesive tape with a carrier or a transfer adhesive tape. In the present case, an embodiment is selected as a transfer adhesive tape.

Examples

All quantities in the following examples are parts by weight based on the total composition. Test Methods

adhesive power

The determination of the bond strength was carried out as follows:

As a defined primer a steel surface, a polyethylene terephthalate (PET) and a polyethylene plate (PE) was used. The glued surface element to be examined was cut to a width of 20 mm and a length of about 25 cm, provided with a handling section and immediately thereafter pressed five times with a steel roller of 4 kg at a feed rate of 10 m / min on the selected primer. Immediately thereafter, the previously bonded surface element at an angle of 180 ° at room temperature and at 300 mm / min was removed from the primer with a tensile tester (Zwick) and measured the force required for this purpose. The measured value (in N / cm) was the average of three individual measurements.

Life test

As a measure of the determination of the life of an (opto) electronic structure, a Caiciumtest was used. For this purpose, a 20 × 20 mm ² large, thin calcium layer is deposited on a glass plate under a nitrogen atmosphere. The thickness of the calcium layer is about 100 nm. For the encapsulation of the calcium layer, an adhesive tape with the adhesive to be tested and a thin glass plate (35 μηι, Schott) is used as a carrier material. The adhesive tape is applied with an all-round edge of 3 mm above the calcium level in which it adheres directly to the glass plate. Due to the impermeable glass carrier of the adhesive tape only the permeation is determined by the pressure-sensitive adhesive.

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 the time to halve the area of the calcium level called lifetime. As measuring conditions are 60 ° C and 90% relative humidity selected. The samples were glued with a layer thickness of the PSA of 15 μιτι full surface and free of bubbles.

Production of the patterns

The pressure-sensitive adhesives in Examples 1 to 3 were prepared from solution. For this purpose, the individual components were dissolved in toluene (solids content 40%) and coated on an untreated 23 μιτι PET film and dried at 120 ° C for 15 minutes, so that an adhesive layer with a basis weight of 50 g / m ² was formed. For the life test samples were prepared in the same way, but the coating was not carried out on a PET film but on a with 1, 5 g / m ² siliconized release paper with a Klebmasseschichtdicke of 15 g / m ² .

Preparation of Polymer 1:

Tuftec P 1500: partially hydrogenated styrene-butadiene-styrene block copolymer with hydrogenated

Vinyl groups in the side chains with 30 wt .-%

Block polystyrene content, 78 wt .-% diblock from Asahi

100 parts of Tuftec P 1500 were dissolved in dry toluene to give a 20% solution. Subsequently, 1 part of tnmethoxyvinylsilane and 0.2 part of benzoyl peroxide are added. The solution is boiled for 2 h and then the polymer is precipitated in dry ethanol, washed with dry ethanol and dried at 60.degree.

example 1

100 parts of polymer 1

50 parts Escorez 5690 Hydrogenated Hydrocarbon Resin r with a

Softening point of 90 ° C Exxon

50 parts Escorez 5615 Hydrogenated hydrocarbon resin with a

Softening point of 115 ° C Exxon

Example 2

50 parts Kraton FG 1924 maleic anhydride modified SEBS with 13% by weight Block polystyrene content, 36 wt .-% diblock and 1 wt .-%

Maleic acid from Kraton

50 parts Kraton FG 1901 maleic anhydride modified SEBS with 30% by weight

Block polystyrene content, without diblock and with 1, 7 wt .-%

Maleic acid from Kraton

2.5 parts KR-TTS isopropyl triisostearoyl titanate from Kenrich

70 parts Escorez 5615 Hydrogenated hydrocarbon resin with a

Softening point of 115 ° C Exxon

25 parts of Ondina 917 white oil from paraffinic and naphthenic portions of

Company Shell

Example 3 100 parts of Epofriend AT-501, an epoxidized SBS from Daicel, and 4 parts of Dynasylan 1122 (bis (3-triethoxysilyl-propyl) amine) are mixed in a melt kneader at 160 ° C. After the elastomer has melted homogeneously, 80 parts of Pentalyn H (Eastman's rosin ester) and 20 parts of Wingtack 10 (Cray Valley liquid C5 resin) are added.

The adhesive is coated using a two-roll mill on a siliconized release paper with a coating weight of 50g / m ² .

Example 4

50 parts Kraton FG 1924 maleic anhydride modified SEBS with 13% by weight

Block polystyrene content, 36 wt .-% diblock and 1 wt .-%

Maleic acid from Kraton

50 parts Kraton FG 1901 maleic anhydride modified SEBS with 30% by weight

Block polystyrene content, without diblock and with 1, 7 wt .-%

Maleic acid from Kraton

2.5 parts Dynasilan AMEO aminopropyltriethoxysilane

20 parts Escorez 5615 Hydrogenated HC resin with a softening point of 115 ° C Exxon

1.5 parts of aluminum acetylacetonate

This example is not a pressure sensitive adhesive but a hot melt adhesive that needs to be heated to stick. For the measurements it was heated for 5 s to 80 ° C during the gluing.

Comparative Example V5

100 parts of Tuftec P 1500 partially hydrogenated styrene-butadiene-styrene block copolymer having hydrogenated vinyl groups in the side chains with 30 wt .-% block polystyrene content, 78 wt .-% diblock from Asahi

50 parts Escorez 5690 Hydrogenated hydrocarbon resin with a

Softening point of 90 ° C Exxon

50 parts Escorez 5615 Hydrogenated hydrocarbon resin with a

Softening point of 115 ° C Exxon

Comparative Example V6

100 parts Kraton FG 1924 maleic anhydride modified SEBS with 13% by weight

Block polystyrene content, 36 wt .-% diblock and 1 wt .-% maleic acid Kraton

50 parts Escorez 5690 Hydrogenated hydrocarbon resin with a

Softening point of 90 ° C Exxon

50 parts Escorez 5615 Hydrogenated hydrocarbon resin with a

Softening point of 115 ° C Exxon Results:

Adhesive force [N / cm] lifetime

Steel / PET / PE [h]

Example 1 7.2 / 6.1 / 3.6 550

Example 2 4.7 / 4.3 / 2.9 430

Example 3 7.6 / 6.3 / 4.0 490

Example 4 8.6 / 6.7 / 3.4 560

V5 6.7 / 5.8 / 3.3 280

V6 4.8 / 3.9 / 2.2 260

As can be seen, although sufficiently high bond strengths could be achieved in all examples. However, the lifetime test was significantly better for all organometallic modified adhesives.

Claims

claims

1. Use of an adhesive for the encapsulation of an (opto) electronic application containing an organometallic modified polymer formed by reaction of an elastomer with an organometallic compound, wherein the central atom of the organometallic compound is a metal or semimetal of the 3rd and 4th main group or the 3rd and 4th subgroup is.

2. Use of an adhesive according to claim 1,

characterized in that

it is a pressure-sensitive adhesive,

3. Use of an adhesive according to claim 1,

characterized in that

it is a hotmelt adhesive,

4. Use of an adhesive according to at least one of claims 1 to 3,

characterized in that

the central atom is silicon, tin, lead, titanium or zirconium

5. Use of an adhesive according to at least one of the preceding claims, characterized in that

the organometallic modified polymer is formed from a reaction of an acid anhydride or epoxide modified polymer and an organometallic compound of the following structure: R ¹ ) m With

M = metal of the 3rd and 4th main group and the 3rd and 4th subgroup

R ¹ , R ² = independently selected from the group methyl, ethyl,

2-methoxyethyl, i-propyl, butyl

m = 1 to 3 n = 1 to 12

p = 1 or 2

and

for p = 1

Y = a functional group selected from the group

or

for p

Y = NH

Use of an adhesive according to at least one of the preceding claims, characterized in that

the organometallic modified polymer is formed from a reaction of a double bond-containing polymer and an organometallic compound of the following structure.

(OR ¹ ) _m

CH ₂ = C - _C - O ^ - (CH ₂ ) _n M (R ² ) _3-m

R ³ O with

M = metal of the 3rd and 4th main group and the 3rd and 4th subgroup

R ¹ , R ² = independently selected from the group methyl, ethyl,

2-methoxyethyl, i-propyl, butyl

R ³ = H or CH ₃

m = 1 to 3

n = 1 to 12

x = 0 or 1

7. Use of an adhesive according to at least one of the preceding claims, characterized in that

the polymer is a vinyl aromatic block copolymer.

A method for encapsulating an electronic device against permeants, in which a pressure-sensitive adhesive composition according to at least one of the preceding claims is provided and in which the PSA is applied to and / or around the areas of the electronic device to be encapsulated.

Method according to claim 9,

characterized in that

the pressure-sensitive adhesive and / or the areas of the electronic arrangement to be encapsulated are heated before, during and / or after the application of the PSA.

Electronic arrangement with an electronic structure, in particular an organic electronic structure, and a pressure-sensitive adhesive according to at least one of the preceding claims, wherein the electronic structure is at least partially encapsulated by the pressure-sensitive adhesive.