Abstract:
Provided are a pressure-sensitive adhesive composition, an encapsulation film including the same, an organic electronic device including the same, and a method of manufacturing the organic electronic device. Therefore, provided is the pressure-sensitive adhesive composition, which can form a structure capable of effectively blocking moisture or water entering the organic electronic device from the outside, and have excellent processability in a process of manufacturing a panel and excellent heat retention under a high-temperature and high-humidity condition.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 2015-0017620, filed on Feb. 4, 2015 with the Korean Intellectual Property Office, the disclosure of which is herein incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present application relates to a pressure-sensitive adhesive composition, an encapsulation film including the same, an organic electronic device (OED) including the same, and a method of manufacturing an OED using the same. 
         [0004]    2. Discussion of Related Art 
         [0005]    An OED is a device including an organic material layer in which electric charges are exchanged using holes and electrons, and the OED may be, for example, a photovoltaic device, a rectifier, a transmitter, or an organic light emitting diode (OLED). 
         [0006]    Among the OEDs, an OLED has lower power consumption and a higher response speed, and is advantageous to a thinner display device or lighting than a conventional light source. Such an OLED also has excellent space applicability, and is expected to be applied to various fields including all kinds of portable devices, monitors, notebook computers and TVs. 
         [0007]    For commercialization and expanded use of the OLED, the most critical problem is durability. Organic materials and metal electrodes included in the OLED are very easily oxidized by an external factor, for example, moisture. Therefore, a product including an OLED is very sensitive to environmental factors. For this reason, various methods have been suggested to effectively prevent the permeation of oxygen or moisture into an OED such as an OLED from the outside. 
         [0008]    In Patent Document 1, an adhesive capsulation composition film and an organic electroluminescent element are disclosed, and the composition is a polyisobutylene (PIB)-based pressure-sensitive adhesive, but has low processability and low reliability under a high-temperature and high-humidity condition. In addition, in a process of laminating large-scale flat panels, air bubbles are enclosed between the panels, and therefore a uniform laminating property may not be obtained. 
         [0009]    Therefore, there is a demand for developing an encapsulant, which allows an OED to ensure a demanded lifespan, effectively prevents the permeation of moisture into the OED, maintains reliability under a high-temperature and high-humidity condition, and has an excellent laminating property, which is one of the characteristics required during a process of manufacturing a panel. 
       PRIOR ART 
     Patent Document 
       [0000]    
       
         (Patent Document 1) Korean Unexamined Patent Application Publication No. 2008-0088606 
       
     
       SUMMARY OF THE INVENTION 
       [0011]    The present application provides a pressure-sensitive adhesive composition and an encapsulation film, which can form a structure capable of effectively blocking moisture or oxygen entering an OED from the outside, have excellent processability during a process of manufacturing a panel and excellent heat retention under a high-temperature and high-humidity condition. 
         [0012]    Hereinafter, with reference to the accompanying drawings, exemplary embodiments of the present application will be described in further detail. In addition, to explain the present application, detailed descriptions for known general functions or configurations will be omitted. In addition, the accompanying drawings are schematically provided to help in understanding the present application. To more clearly explain the present application, parts not relating to the explanation will be omitted, thicknesses are exaggerated to clearly express several layers and regions. The scope of the present application is not limited by thicknesses, sizes, and ratios shown in the drawings. 
         [0013]    The present application relates to a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may be applied to encapsulate or capsulate an OED such as an OLED. 
         [0014]    The term “organic electronic device (OED)” used herein is a product or device having a structure including an organic material layer in which electric charges are exchanged using holes and electrons between a pair of electrodes facing each other, and examples of the OED may include, but the present application is not limited to, a photovoltaic device, a rectifier, a transmitter, and an OLED. In an exemplary embodiment of the present application, the OED may be an OLED. 
         [0015]    The pressure-sensitive adhesive composition of the present application may be formed in an encapsulation film to seal the entire surfaces of the organic electronic element, and thus may protect the element from moisture or oxygen. Such a pressure-sensitive adhesive composition may include a polymer derived from butylene. Also, the composition may have a Mooney viscosity (η*) of 5000 to 10 7  Pa·s measured by a shear stress using a planar jig having a diameter of 8 mm at a strain of 5%, a frequency of 1 Hz and any one temperature point in the range of 30 to 150° C. The Mooney viscosity may be measured by a known method, for example, an ARES (TA). The range of the viscosity may be, for example, 5,000 to 10 7  Pa·s, 5,000 to 5×10 6  Pa·s, 6,500 to 5×10 5  Pa·s, 10,000 to 4×10 5  Pa·s, 15,000 to 3×10 5  Pa·s, or 50,000 to 2×10 5  Pa·s. Within the viscosity range, the pressure-sensitive adhesive composition of the present application is controlled in flowability even at high temperature while formed in a film in the process of manufacturing a panel, and thus a connection failure caused by fouling of a tool, formation of a coating film on an interconnection, etc. may be prevented. 
         [0016]    The term “advanced rheometric expansion system (ARES)” is a rheometer evaluating viscoelastic properties such as viscosity, shear modulus, loss factor and storage modulus of a material. The instrument is a mechanical measuring device that can apply dynamic and normal states to a sample and measure a transfer torque to an extent that the sample is resistant to the stress applied as described above. 
         [0017]    The pressure-sensitive adhesive composition may include a polymer derived from butylene, and additionally include a compound satisfying Formula 1. The compound of Formula 1 may include a monofunctional acrylate. 
         [0018]    The monofunctional acrylate may be the compound satisfying Formula 1. 
         [0000]    
       
                 
         
             
             
         
       
     
         [0019]    In Formula 1, T may be a linear or branched alkyl group, alkenyl group or alkynyl group. The alkyl, alkenyl group or alkynyl group may have a linear or branched structure having 6 to 30, 7 to 25, 8 to 23, 9 to 20, 10 to 19, 6 to 17 or 6 to 11 carbon atoms. Also, T may be —U[O—W] n —O-Q. Here, U and W are each independently an alkylene group or alkylidene group, and Q is an alkyl group, alkenyl group, alkynyl group or aryl group. Also, n is a number from 0 to 10, and when n is 0, U may be directly linked to —O-Q. Since the pressure-sensitive adhesive composition of the present application includes both of a hydrophobic polymer and the specific compound of Formula 1, when applied to encapsulation of the organic electronic element, the composition can exhibit excellent processability during the process of manufacturing a panel and excellent heat retention under a high-temperature and high-humidity condition. In an exemplary embodiment, the composition may include 60 to 95 parts by weight of the polymer derived from butylene and 5 to 40 parts by weight of the compound satisfying Formula 1. In an exemplary embodiment, the composition may include 60 to 90 parts by weight of the polymer derived from butylene and 10 to 40 parts by weight of the compound satisfying Formula 1, or 65 to 90 parts by weight of the polymer derived from butylene and 10 to 35 parts by weight of the compound satisfying Formula 1. In the present application, as the contents of the components are adjusted in the above-described ranges, an excellent moisture blocking property and heat retention under a high-temperature and high-humidity condition may be realized. The compound of Formula 1 may include, but is not particularly limited to, n-octyl acrylate, iso-octyl acrylate, iso-nonyl acrylate, lauryl acrylate, stearyl acrylate, isostearyl acrylate, isodecyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, methoxytriethyleneglycol acrylate, or methoxypolyethyleneglycol acrylate. 
         [0020]    The term “alkyl group” used herein may be, unless particularly defined otherwise, an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched or cyclic structure, and may be arbitrarily substituted with at least one substituent. 
         [0021]    Also, the term “alkenyl group” or “alkynyl group” used herein may be, unless particularly defined otherwise, an alkenyl or alkynyl group having 2 to 20, 2 to 16, 2 to 12, 2 to 8, or 2 to 4 carbon atoms. The alkenyl or alkynyl group may be linear, branched or cyclic. Also, the alkenyl group may be arbitrarily substituted with at least one substituent. 
         [0022]    Also, the term “alkylene group” or “alkylidene group” used herein may be, unless particularly defined otherwise, an alkylene or alkylidene group having 2 to 30, 2 to 25, 2 to 20, 2 to 16, 2 to 12, 2 to 10, or 2 to 8 carbon groups. The alkylene group or an alkylidene group may be linear, branched or cyclic. Also, the alkylene or alkylidene group may be arbitrarily substituted with at least one substituent. 
         [0023]    The term “aryl group” used herein may be, unless particularly defined otherwise, a monovalent residue derived from a compound including a structure in which benzene is included, or two or more benzenes are condensed or coupled or a derivative thereof. The aryl group may have 6 to 22, preferably 6 to 16, and more preferably 6 to 13 carbon atoms, and may be, for example, a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group, a xylyl group or a naphthyl group. 
         [0024]    The term “polymer derived from butylene” may mean that one or more polymerization units of the polymer are derived from butylene. Since the polymer derived from butylene has a very low polarity, is transparent and almost has no influence of corrosion, when used as an encapsulant or sealant, the polymer may exhibit an excellent moisture blocking property and excellent durability and reliability. 
         [0025]    In the present application, also, the polymer derived from butylene may be a homopolymer of a butylene monomer; a copolymer formed by copolymerizing a butylene monomer with a different polymerizable monomer; a reactive oligomer using a butylene monomer; or a mixture thereof. The polymer derived in the present application refers that a polymer is formed with a unit of polymerized monomers. The butylene monomer may include, for example, 1-butene, 2-butene or isobutylene. 
         [0026]    The butylene monomer or the different monomer capable of being polymerized with a derivative may include, for example, isoprene, styrene or butadiene. When the copolymer is used, physical properties such as processability and a crosslinking degree may be maintained, and therefore, when applied to the OED, thermal resistance of the pressure-sensitive adhesive itself may be ensured. 
         [0027]    Also, the reactive oligomer using a butylene monomer may include a butylene polymer having a reactive functional group. The oligomer may have a weight average molecular weight of 500 to 5000. Also, the butylene polymer may be linked to a different polymer having a reactive functional group. The different polymer may be an alkyl (meth)acrylate, but the present application is not limited thereto. The reactive functional group may be a hydroxyl group, a carboxyl group, an isocyanate group or a nitrogen-containing group. Also, the reactive oligomer and the different polymer may be crosslinked by a multifunctional crosslinking agent, which may be one or more selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent and a metal chelate crosslinking agent. 
         [0028]    In an exemplary embodiment, the polymer derived from butylene of the present application may be a copolymer of diene and an olefin-based compound including one carbon-carbon double bond. Here, the olefin-based compound may include butylene, and the diene may be a monomer capable of being polymerized with the olefin-based compound, for example, isoprene or butadiene. For example, the copolymer of the olefin-based compound including a carbon-carbon double bond and diene may be butyl rubber. 
         [0029]    In the present application, the polymer may have a certain weight average molecular weight (MW) so that a pressure-sensitive adhesive composition can be molded in a film shape. For example, the polymer may have a weight average molecular weight of about 10,000 to 2,000,000, 10,000 to 1,000,000, 10,000 to 500,000 or 10,000 to 300,000. In the present application, the term “weight average molecular weight” is a value converted with respect to standard polystyrene measured by gel permeation chromatography (GPC). However, the above-described weight average molecular weight does not necessarily have a resin component. For example, even when the molecular weight of the resin component is not enough to form a film, a separate binder resin may be blended in the pressure-sensitive adhesive composition. The terms “polymer” and “resin component” may have the same meaning as each other. 
         [0030]    In an exemplary example of the present application, the pressure-sensitive adhesive composition may further include a multifunctional active energy ray polymerizable compound, which can be polymerized by irradiation with an active energy ray. The active energy ray polymerizable compound may satisfy Formula 2. 
         [0000]    
       
                 
         
             
             
         
       
     
         [0031]    In Formula 2, R 1  is hydrogen or an alkyl group having 1 to 4 carbon atoms, n is an integer of 2 or higher, and X is a residue derived from a linear, branched or cyclic alkyl group having 3 to 30 carbon atoms. 
         [0032]    The active energy ray polymerizable compound satisfying Formula 2 particularly has an excellent compatibility with the polymer of the present application, and therefore can satisfy reliability under a high-temperature and high-humidity condition. For example, the active energy ray polymerizable compound may realize a pressure-sensitive adhesive composition having an excellent moisture blocking property and excellent reliability under a high-temperature and high-humidity condition, along with the above-described polymer derived from butylene. 
         [0033]    The active energy ray polymerizable compound may refer to a compound including two or more functional groups capable of participating in a polymerization reaction by irradiation with an active energy ray, for example, functional groups including an ethylene-like unsaturated double bond such as an acryloyl or methacryloyl group, and functional groups such as an epoxy or oxetane group. 
         [0034]    As described above, the active energy ray polymerizable compound may satisfy Formula 2. 
         [0000]    
       
                 
         
             
             
         
       
     
         [0035]    In Formula 2, R 1  is hydrogen or an alkyl group having 1 to 4 carbon atoms, n is an integer of 2 or higher, and X is a residue derived from a linear, branched or cyclic alkyl group having 3 to 30 carbon atoms. Here, when X is a residue derived from a cyclic alkyl group, X may be a residue derived from a cyclic alkyl group having 3 to 30, 6 to 28, 8 to 22, or 12 to 20 carbon atoms. Also, when X is a residue derived from a linear alkyl group, X may be a residue derived from a linear alkyl group having 3 to 30, 6 to 25, or 8 to 20 carbon atoms. Also, when X is a residue derived from a branched alkyl group, X may be a residue derived from a branched alkyl group having 3 to 30, 5 to 25, or 6 to 20 carbon atoms. 
         [0036]    The term “residue derived from an alkyl group” used herein may refer to a residue of a specific compound, for example, an alkyl group. In one example, in Formula 2, when n is 2, X may be an alkylene group. Also, when n is 3 or higher, two or more hydrogen atoms are released from an alkyl group of X, and may be bound to a (meth)acryloyl group of Formula 2. 
         [0037]    The multifunctional active energy ray polymerizable compound capable of being polymerized by the radiation of an active energy ray may be used without limitation as long as satisfying Formula 2. For example, the compound may be 1,4-butanediol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, cyclohexane-1,4-dimethanol di(meth)acrylate, tricyclodecanedimethanol (meth)diacrylate, dimethylol dicyclopentane di(meth)acrylate, neopentyl glycol-modified trimethylpropane di(meth)acrylate, adamantane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, or a mixture thereof. 
         [0038]    As the multifunctional active energy ray polymerizable compound, for example, a compound having a molecular weight of less than 1,000 and including two or more functional groups may be used. In this case, the molecular weight may refer to a weight average molecular weight or a conventional molecular weight. A ring structure included in the multifunctional active energy ray polymerizable compound may be any one of a carbocyclic structure, a heterocyclic structure, a monocyclic structure or a polycyclic structure. 
         [0039]    In an exemplary embodiment, the composition may include 50 to 90 parts by weight of the polymer derived from butylene, 5 to 35 parts by weight of the compound satisfying Formula 1, and 5 to 25 parts by weight of the multifunctional active energy ray polymerizable compound of Formula 2. In an exemplary embodiment, the pressure-sensitive adhesive composition may include the polymer derived from butylene, the compound satisfying Formula 1 and the multifunctional active energy ray polymerizable compound of Formula 2 in a weight ratio of 50 to 85 parts by weight, 5 to 30 parts by weight and 10 to 25 parts by weight; or 60 to 85 parts by weight, 10 to 30 parts by weight and 2 to 20 parts by weight, respectively. In the present application, as the contents of the components are adjusted in the above ranges, an excellent moisture blocking property and heat retention under a high-temperature and high-humidity condition may be realized. 
         [0040]    In an exemplary embodiment, the pressure-sensitive adhesive composition may further include a tackifier, which is preferably a hydrogenated cyclic olefin-based polymer. As the tackifier, for example, a hydrogenated petroleum resin obtained by hydrogenating a petroleum resin may be used. The hydrogenated petroleum resin may be partially or completely hydrogenated, or a mixture of such resins may be used. For the tackifier, one having a high compatibility with a pressure-sensitive adhesive composition, an excellent moisture blocking property, and a low content of an organic volatile component may be selected. As a specific example of the hydrogenated petroleum resin, a hydrogenated terpene-based resin, a hydrogenated ester-based resin or a hydrogenated dicyclopentadiene-based resin may be used. A weight average molecular weight of the tackifier may be about 200 to 5,000. The content of the tackifier may be suitably adjusted as necessary. For example, a content of the tackifier may be selected by considering the compatibility with a polymer, and according to an exemplary embodiment, the tackifier may be included at 5 to 100 parts by weight, 8 to 95 parts by weight, 10 to 93 parts by weight or 15 to 90 parts by weight with respect to 100 parts by weight of the polymer. 
         [0041]    In an exemplary embodiment of the present application, the pressure-sensitive adhesive composition may further include a radical initiator capable of inducing the polymerization reaction of the above-described active energy ray polymerizable compound. The radical initiator may be a photoinitiator or a thermal initiator. A specific type of the photoinitiator may be suitably selected by considering a curing rate and yellowing probability. For example, a benzoin-based, hydroxy ketone-based, amino ketone-based or phosphine oxide-based photoinitiator may be used, and specifically, benzoin, benzoin methylether, benzoin ethylether, benzoin isopropylether, benzoin n-butylether, benzoin isobutylether, acetophenone, dimethylamino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexyl phenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] or 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide may be used. 
         [0042]    The radical initiator may be included at 0.2 to 20 parts by weight, 0.5 to 18 parts by weight, 1 to 15 parts by weight, or 2 to 13 parts by weight with respect to 100 parts by weight of the active energy ray polymerizable compound. Therefore, a reaction of the active energy ray polymerizable compound may be effectively induced, and degradation of the physical properties of the pressure-sensitive adhesive composition due to a component remaining after curing may be prevented. 
         [0043]    The pressure-sensitive adhesive composition may further include a moisture scavenger when needed. The term “moisture scavenger” may refer to a material capable of removing moisture or vapor permeated into an encapsulation film that will be described later by a chemical reaction therewith. Specifically, the pressure-sensitive adhesive composition may be applied to encapsulate an OED, when formed in a film. 
         [0044]    For example, the moisture scavenger may be present in a uniformly dispersed state in the pressure-sensitive adhesive composition or a pressure-sensitive adhesive layer that will be described later. Here, the uniformly dispersed state may mean a state in which the moisture scavenger is present even in any part of the pressure-sensitive adhesive composition or the pressure-sensitive adhesive layer at the same or substantially the same density. As the moisture scavenger, for example, a metal oxide, a sulfate or an organic metal oxide may be used. Specifically, as an example of the sulfate, magnesium sulfate, sodium sulfate or nickel sulfate may be used, and as an example of the organic metal oxide, aluminum oxide octylate may be used. Here, a specific example of the metal oxide may be phosphorous pentoxide (P 2 O 5 ), lithium oxide (Li 2 O), sodium oxide (Na 2 O), barium oxide (BaO), calcium oxide (CaO) or magnesium oxide (MgO), and an example of the metal salt may be a sulfate such as lithium sulfate (Li 2 SO 4 ), sodium sulfate (Na 2 SO 4 ), calcium sulfate (CaSO 4 ), magnesium sulfate (MgSO 4 ), cobalt sulfate (CoSO 4 ), gallium sulfate (Ga 2 (SO 4 ) 3 ), titanium sulfate (Ti(SO 4 ) 2 ) or nickel sulfate (NiSO 4 ), or a metal halide such as calcium chloride (CaCl 2 ), magnesium chloride (MgCl 2 ), strontium chloride (SrCl 2 ), yttrium chloride (YCl 3 ), copper chloride (CuCl 2 ), cesium fluoride (CsF), tantalum fluoride (TaF 5 ), niobium fluoride (NbF 5 ), lithium bromide (LiBr), calcium bromide (CaBr 2 ), cesium bromide (CeBr 3 ), selenium bromide (SeBr 4 ), vanadium bromide (VBr 3 ), magnesium bromide (MgBr 2 ), barium iodide (BaI 2 ) or magnesium iodide (MgI 2 ); or a metal chlorate such as barium perchloride (Ba(ClO 4 ) 2 ) or magnesium perchloride (Mg(ClO 4 ) 2 ), but the present application is not limited thereto. As the moisture scavenger that can be included in the pressure-sensitive adhesive composition, one or two or more of the above-described components may be used. In an exemplary embodiment, when the two or more of the above-described components are used as the moisture scavenger, calcined dolomite may be used. 
         [0045]    Such a moisture scavenger may be controlled in a suitable size according to use. In an exemplary embodiment, an average particle size of the moisture scavenger may be controlled to about 10 to 15000 nm. The moisture scavenger having a size in the above range may be easily stored since a reaction speed of the moisture scavenger with moisture is not so fast, and effectively remove moisture without a damage to an element to be encapsulated. 
         [0046]    A content of the moisture scavenger may be suitably selected by considering a desired blocking property without particular limitation. 
         [0047]    The pressure-sensitive adhesive composition may also include a moisture blocker when needed. The term “moisture blocker” used herein may be a material that has no reactivity with moisture or can prevent or interfere with the movement of moisture or vapor in a film. As the moisture blocker, one or two or more of clay, talc, needle-like silica, plate-like silica, porous silica, zeolite, titania and zirconia may be used. Also, a surface of the moisture blocker may be treated with an organic modifier to facilitate penetration of an organic material. Such an organic modifier may be, for example, dimethyl benzyl hydrogenated tallow quaternary ammonium, dimethyl hydrogenated tallow quaternary ammonium, methyl tallow bis-2-hydroxyethyl quaternary ammonium, dimethyl hydrogenated tallow 2-ethylhexyl quaternary ammonium, dimethyl dehydrogenated tallow quaternary ammonium or a mixture thereof. 
         [0048]    A content of the moisture blocker may be suitably selected by considering a desired blocking property without particular limitation. 
         [0049]    In addition to the above-described components, various additives may be included in the pressure-sensitive adhesive composition according to its use and process of manufacturing a pressure-sensitive adhesive film that will be described later. For example, the pressure-sensitive adhesive composition may include a curable material, a crosslinking agent, or a filler in a suitable range of content according to a desired physical property. 
         [0050]    The present application also relates to an encapsulation film. The encapsulation film may include the above-described pressure-sensitive adhesive composition or a pressure-sensitive adhesive layer including a crosslinked product thereof. 
         [0051]    In an exemplary embodiment, the pressure-sensitive adhesive layer may have a single layer structure or a multilayer structure having two or more layers. When the pressure-sensitive adhesive layer is formed in two or more layers, the composition of each layer of the pressure-sensitive adhesive layer may be the same as or different from each other. For example, the encapsulation film may include a second layer including the above-described pressure-sensitive adhesive layer and a first layer including a pressure-sensitive adhesive resin or an adhesive resin. The pressure-sensitive adhesive resin included in the first layer may be the same as or different from the above-described polymer, and may be suitably selected by a purpose of those of ordinary skill in the art. Also, each of the first and second layers may or may not include the moisture scavenger. 
         [0052]    In an exemplary embodiment, the adhesive resin included in the first layer may be cured to have an adhesive property, and may include a curable resin having one or more thermally-curable functional groups such as a glycidyl group, an isocyanate group, a hydroxyl group, a carboxyl group or an amide group, or one or more functional groups capable of being cured by irradiation with electromagnetic waves, for example, an epoxide group, a cyclic ether group, a sulfide group, an acetal group or a lactone group. Also, a specific type of the resin may be, but is not limited to, an acryl resin, a polyester resin, an isocyanate resin or an epoxy resin. 
         [0053]    In the present application, as the curable resin, an aromatic or aliphatic epoxy resin; or a linear or branched epoxy resin may be used. In an exemplary embodiment of the present application, the curable resin containing two or more functional groups may be an epoxy resin having an epoxy equivalent of 180 to 1,000 g/eq. By using the epoxy resin having the above range of equivalent, properties such as an adhesion performance and a glass transition temperature of a cured product may be effectively maintained. As an example of the epoxy resin, one of a cresol novolac epoxy resin, a bisphenol A-type epoxy resin, a bisphenol A-type novolac epoxy resin, a phenol novolac epoxy resin, a tetrafunctional epoxy resin, a biphenyl-type epoxy resin, a triphenol methane-type epoxy resin, an alkyl modified triphenol methane epoxy resin, a naphthalene-type epoxy resin, a dicyclopentadiene-type epoxy resin and a dicyclopentadiene modified phenol-type epoxy resin, or a mixture of at least two thereof may be used. 
         [0054]    In an exemplary embodiment of the present application, the first layer or the second layer may include other components such as the above-described active energy ray polymerizable compound, a radical initiator, a tackifier, a moisture scavenger, a moisture blocker, a dispersant or a silane compound as well as the above-described resin, and the components of the first and second layers may be the same as or different from each other. Also, the second layer may include a curable material, a curing agent, or a filler in a suitable range of content depending on a desired physical property. Meanwhile, the content of the moisture scavenger may be controlled depending on a damage of the element by considering the fact that the encapsulation film is applied in encapsulating the organic electronic element. For example, a small amount of or no moisture scavenger may be included in the layer in contact with the element. In an exemplary embodiment, the second layer in contact with the element may include the moisture scavenger at 0 to 20% of the total mass of the moisture scavenger contained in the encapsulation film. Also, the first layer not in contact with the element may include the moisture scavenger at 80 to 100% of the total mass of the moisture scavenger contained in the encapsulation film. 
         [0055]    A sequence of stacking the second layer and the first layer additionally stacked is not particularly limited. For example, the second layer may be formed on the first layer, or on the contrary, the first layer may be formed on the second layer. Also, the encapsulation film may be formed in three or more layers. For example, two or more of the first layers may be included, or two or more of the second layers may be included. 
         [0056]    In an exemplary embodiment, the first layer may have an elastic portion calculated by General Equation 2 of 30 to 80%, and the second layer may have an elastic portion calculated by General Equation 1 of 8 to 40%. 
         [0000]      Ep (unit: %)=100×σ2/σ1  [General Equation 2]
 
         [0057]    In General Equation 2, σ1 is the maximum stress value measured when 30% of stain is applied to the film by applying a normal force of about 200 gf at 85° C. using a parallel plate having a diameter of 8 mm in a stress relaxation test mode of an advanced rheometric expansion system (ARES) while the pressure-sensitive adhesive layer is formed to a thickness of 600 μm, and σ2 is a stress value measured after the state in which the strain is applied to the film is maintained for 180 seconds. Specifically, the pressure-sensitive adhesive layer is first formed to a thickness of 600 μm, and a stress relaxation test mode of the advanced rheometric expansion system (ARES) is used. Here, a normal force of about 200 gf is applied at 85° C. using a parallel plate having a diameter of 8 mm. σ1 is the maximum stress value measured when 30% of strain is applied to the film, and σ2 is a stress value measured after the state in which the strain is applied to the film is maintained for 180 seconds. 
         [0058]    As described above, the encapsulation film may be applied to encapsulate or capsulate the OED such as an OLED. The encapsulation film exhibiting the value (Ep) range may be formed in an encapsulating or capsulating structure with excellent durability without generating air bubbles under a high temperature durability test condition when applied to an encapsulation or capsulation process. In an exemplary embodiment, the encapsulation film may be used, as will be described later, to form the encapsulating or capsulating structure covering the top and side surfaces of an element of the OED. 
         [0059]    The term “advanced rheometric expansion system (ARES)” is a rheometer evaluating viscoelastic properties such as viscosity, shear modulus, loss factor and storage modulus of a material. The instrument is a mechanical measuring device that can apply dynamic and normal states to a sample and measure a transfer torque to an extent that the sample is resistant to the stress applied as described above. 
         [0060]    In an exemplary embodiment, the encapsulation film of the present application may be directly attached to a metal layer on the first layer of the pressure-sensitive adhesive layer. The term “directly attached” used herein may mean that there is no layer between two layers. Also, the second layer may be attached to a substrate on which an element is formed to entirely seal the element. That is, the second layer may be directly attached to the substrate. 
         [0061]    In an exemplary embodiment, the value Ep calculated by General Equation as described above of the first layer of the exemplary encapsulation film may be 30 to 80%, 30 to 75% or 30 to 70%. Also, the value Ep calculated by General Equation 2 as described above of the second layer may be 8 to 40%, 10 to 40% or 20 to 40%. In the present application, the adhesive durability and reliability of the first layer may be excellently maintained by controlling the Ep value within the above range by considering that the first layer is directly attached to the metal layer. Also, in the present application, the lamination quality between the substrate and the encapsulation film of the second layer may be achieved by controlling the Ep value within the above range. The value of the elastic portion of the first layer according to the present application may be the same as or higher than the value of the elastic portion of the second layer, but the present application is not limited thereto. 
         [0062]    In an exemplary embodiment of the present application, the first layer may have a probe tack force measured according to ASTM D2979 within a range of 50 to 500 gf, and specifically, the first layer may have a probe tack force of 60 to 450 gf or 70 to 400 gf. Also, the second layer may have a probe tack force measured according to ASTM D2979 within a range of 3 to 100 gf, and specifically, the second layer may have a probe tack force of 3 to 90 gf. 
         [0063]    Also, while formed to a thickness of 100 μm, the pressure-sensitive adhesive layer of the encapsulation film according to the present application may have a water vapor transmission rate (WVTR) of 50, 40, 30, 20 or 10 g/m 2 ·day or less, which is measured in a thickness direction of the film at 100° F. and a relative humidity of 100%. As the composition or crosslinking condition of the pressure-sensitive adhesive are adjusted to have such a WVTR, when the pressure-sensitive adhesive is applied to the encapsulation or capsulation structure of the electronic device, the encapsulation or capsulation structure may effectively block moisture or oxygen permeated from the outside and thus stably protect the element. As the WVTR is lower, a more excellent moisture blocking property may be exhibited, and therefore, the lower limit may be, but is not particularly limited to, for example, 0 g/m 2 ·day. 
         [0064]    In an exemplary embodiment of the present application, the encapsulation film may further include a metal layer. The metal layer according to an exemplary embodiment of the present application may be transparent or opaque. The metal layer may be formed by depositing a metal on a thin metal foil or a polymer base film. For the metal layer, any material having thermal conductivity and a moisture blocking property may be used without limitation. The metal layer may include any one of a metal, a metal oxide, a metal nitride, a metal carbide, a metal oxynitride, a metal oxyboride, and a blend thereof. For example, the metal layer may include an alloy of two or more metals, for example, an iron-nickel alloy. Also, in one example, the metal layer may include a metal oxide such as silicon oxide, aluminum oxide, titanium oxide, indium oxide, tin oxide, tin indium oxide, tantalum oxide, zirconium oxide, niobium oxide or a blend thereof. The metal layer may be deposited using a means for electrolysis, rolling, heated evaporation, electron beam evaporation, sputtering, reactive sputtering, chemical vapor deposition, plasma chemical vapor deposition or electron cyclotron resonance plasma source chemical vapor deposition. In one exemplary embodiment of the present application, the metal layer may be deposited by reactive sputtering. 
         [0065]    Preferably, the metal layer may have a thermal conductivity of 50 W/mK or more, 60 W/mK or more, 70 W/mK or more, 80 W/mK or more, 90 W/mK or more, 100 W/mK or more, 110 W/mK or more, 120 W/mK or more, 130 W/mK or more, 140 W/mK or more, 150 W/mK or more, 200 W/mK or more, or 250 W/mK or more. Due to the high thermal conductivity, heat generated at a laminating interface in a process of laminating the metal layer may be more rapidly emitted. Also, because of the high thermal conductivity, heat accumulated in the operation of the OED may be quickly emitted to an outside, and thus a temperature of the OED itself may be maintained lower, and cracks and defects may be reduced. 
         [0066]    The term “thermal conductivity” used herein may be a degree of the ability to transfer heat by conduction, and the unit may be W/mK. The unit is a degree of heat transmission of a material at the same temperature and distance, and refers to the unit (watt) of heat with respect to the unit (meter) of a distance and the unit (kelvin) of a temperature. 
         [0067]    The pressure-sensitive adhesive layer of the exemplary encapsulation film may satisfy General Equation 1. Also, the above-described metal layer may be further included. 
         [0000]        d≦ 1 mm  [General Equation 1]
 
         [0068]    In General Equation 1 d is a creeping distance of the pressure-sensitive adhesive layer creeped behind when a sample prepared by forming the pressure-sensitive adhesive layer having a thickness of 50 μm on one surface of a metal base is attached to a glass in an adhesive area of 1 cm×1 cm, and 500 g of a weight is loaded to the metal base at 85° C. for 1 hour in a gravity direction. Here, the metal base may be formed of copper, aluminum, nickel, invar or stainless steel (SUS). In detail, the surface of the pressure-sensitive adhesive layer of the laminate sample including the pressure-sensitive adhesive layer and the metal base may be attached to the glass in an area of 1 cm×1 cm, and a weight may be loaded to the metal base as described above. The creeping distance of the pressure-sensitive adhesive layer may be measured in a distance of the movement of the metal base. In the general equation, d may be 1 mm or less, for example, 990 μm or less, 950 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, or 400 μm or less. 
         [0069]    The encapsulation film may further include a base film or release film (hereinafter, probably referred to as a “first film”), and have a structure in which the pressure-sensitive adhesive is formed on the base or release film. Also, the structure may further include a base or release film formed on the pressure-sensitive adhesive (hereinafter, also referred to as a “second film”). 
         [0070]      FIGS. 1 and 2  are cross-sectional views of an encapsulation film according to an exemplary embodiment of the present application. 
         [0071]    As shown in  FIG. 1 , the encapsulation film of the present application may include a pressure-sensitive adhesive layer  12  and a metal layer  13 , which are formed on a base film or release film  11 . Also,  FIG. 2  shows the pressure-sensitive adhesive layer  12  including a first layer  12   a  and a second layer  12   b.    
         [0072]    A specific type of the first film capable of being used in the present application is not particularly limited. In the present application, as the first film, for example, a general polymer film used in the art may be used. In the present application, for example, as the base or release film, a polyethyleneterephthalate film, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a vinyl chloride copolymer film, a polyurethane film, an ethylene-vinyl acetate film, an ethylene-propylene copolymer film, an ethylene-acrylic acid ethyl copolymer film, an ethylene-acrylic acid methyl copolymer film or a polyimide film may be used. Also, one or both surfaces of the base film or release film of the present application may be treated with a suitable releasing treatment. As an example of a releasing agent used for the releasing treatment of the base film, an alkyde-, silicone-, fluorine-, unsaturated ester-, polyolefin- or wax-based agent may be used, and for the thermal resistance, an alkyde-, silicone- or fluorine-based releasing agent may be used, but the present application is not limited thereto. 
         [0073]    In the present application, the thickness of the base film or release film (the first film) is not particularly limited, and may be suitably selected according to use. For example, in the present application, the thickness of the first film may be about 10 to 500 μm, and preferably about 20 to 200 μm. When the thickness is less than 10 μm, the base film may be easily deformed in the manufacturing process, and when the thickness is more than 500 μm, economic feasibility is reduced. 
         [0074]    A thickness of the pressure-sensitive adhesive layer included in the encapsulation film of the present application is not particularly limited, and may be suitably selected according to the following condition by considering the use of the film. The thickness of the pressure-sensitive adhesive layer may be about 5 to 200 μm, and preferably about 5 to 100 μm. When the thickness of the pressure-sensitive adhesive layer is less than 5 μm, a sufficient adhesive property may not be ensured, and a rate of the loss of a moisture blocking ability during the process may be increased. When the thickness is more than 200 μm, it is difficult to ensure processability, a space exposed to the side surface may expand so that the moisture blocking property may be degraded, the thermal resistance may be degraded, and the economic feasibility may be deceased. 
         [0075]    The present application also relates to a method of manufacturing an encapsulation film. The method may include molding the pressure-sensitive adhesive layer in a film or sheet shape. 
         [0076]    In an exemplary embodiment, the method may include applying a coating solution including a component constituting the above-described pressure-sensitive adhesive layer to a base or release film in a sheet or film shape, and drying the applied coating solution. 
         [0077]    The coating solution may be prepared by dissolving or dispersing the component of each pressure-sensitive adhesive layer described above in a suitable solvent. In an exemplary embodiment, the pressure-sensitive adhesive layer may be prepared by dissolving or dispersing the moisture scavenger or filler in a solvent when needed, and mixing the moisture scavenger or filler with an encapsulation resin after grinding. 
         [0078]    A type of the solvent used in the preparation of the coating solution is not particularly limited. However, when a dry time of the solvent is too much longer or drying at a high temperature is needed, problems in terms of workability or durability of the encapsulation film may occur, and therefore a solvent having a volatile temperature of 150° C. or less may be used. In consideration of film moldability, a small amount of a solvent having the above range or more of a volatilizing temperature may be mixed. As the solvent, one or two or more of methylethylketone (MEK), acetone, toluene, dimethylformamide (DMF), methylcellosolve (MCS), tetrahydrofuran (THF), xylene and N-methylpyrrolidone (NMP) may be used, but the present application is not limited thereto. 
         [0079]    A method of applying the coating solution to the base or release film is not particularly limited, and thus may be, for example, a known coating method such as knife coating, roll coating, spray coating, gravure coating, curtain coating, comma coating or lip coating. 
         [0080]    The applied coating solution is dried, the solvent is volatilized, and thus a pressure-sensitive adhesive layer may be formed. The drying may be performed, for example, at 70 to 150° C. for 1 to 10 minutes. The drying condition may be changed by considering the used solvent. 
         [0081]    A method of stacking a first layer and a second layer is not particularly limited. For example, the first layer and the second layer, which are formed on respective release films, may be laminated, thereby forming a multi-layered encapsulation film, or the second layer may be formed directly on the first layer and vice versa. 
         [0082]    After drying, a metal layer may be formed on the pressure-sensitive adhesive layer. A method of forming the metal layer may be a technique known in the art. For example, the metal layer may be formed of metal foil, or formed by depositing a metal on a polymer base. For example, the metal layer may be formed by electrolysis or rolling. 
         [0083]    The present application also relates to an OED. The OED may include a substrate; an organic electronic element formed on the substrate; and an encapsulation film encapsulating entire surfaces, for example, all of the top and side surfaces of the organic electronic element. The encapsulation film may include a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive composition in a crosslinked state. Also, the encapsulation film may further include a metal layer formed on the pressure-sensitive adhesive layer. 
         [0084]    Here, the organic electronic element may be, for example, an organic light emitting element. 
         [0085]    Also, the present application relates to a method of manufacturing an OED. The OED may be manufactured using, for example, the encapsulation film. 
         [0086]    The pressure-sensitive adhesive layer may be formed for a structure exhibiting an excellent moisture blocking property in the OED, and effectively fixing and supporting the substrate and the metal layer. 
         [0087]    In addition, the pressure-sensitive adhesive layer may be formed to be stable regardless of a type of the OED, for example, a top emission or bottom emission type. 
         [0088]    The term “pressure-sensitive adhesive layer” used herein may be a pressure-sensitive adhesive covering all of the top and side surfaces of the organic electronic element. 
         [0089]      FIG. 3  is a schematic diagram of an exemplary OED, in which an organic electronic element is an organic light emitting element. 
         [0090]    To manufacture the OED, for example, applying the above-described encapsulation film to the substrate on which the organic electronic element is formed to cover the entire surfaces of the organic electronic element; and curing the encapsulation film may be used. 
         [0091]    The term “curing” used herein may refer to preparation of a pressure-sensitive adhesive by crosslinking the pressure-sensitive adhesive composition of the present application through heating or UV irradiation. 
         [0092]    In detail, the organic electronic element may be formed by forming a transparent electrode on a glass or polymer film used as a substrate through vacuum deposition or sputtering, forming a light emitting organic material layer, for example, consisting of a hole transport layer, an emitting layer and an electron transport layer on the transparent electrode, and further forming an electrode layer thereon. Subsequently, the pressure-sensitive adhesive layer of the encapsulation film is disposed to cover the entire surfaces of the organic electronic element of the substrate, which has gone through the above-described process. 
         [0093]    In an exemplary embodiment, as shown in  FIG. 3 , a product for encapsulating an OED may be disposed such that the pressure-sensitive adhesive layer  12  of the encapsulation film is disposed to be in contact with an OED  22  and a substrate  21 . Also, the metal layer  13  may be disposed on the pressure-sensitive adhesive layer  12 . 
       Effect 
       [0094]    The present application provides a pressure-sensitive adhesive composition, which can form a structure for effectively blocking moisture or oxygen entering an OED from the outside and has an excellent heat retention under a high-temperature and high-humidity condition, and an encapsulation film including the same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0095]      FIGS. 1 and 2  are cross-sectional views of an encapsulation film according to an exemplary embodiment of the present application; and 
           [0096]      FIG. 3  is a cross-sectional view of an OED according to an exemplary embodiment of the present application. 
       
    
    
     EXPLANATION OF REFERENCE NUMERALS 
       [0000]    
       
         
           
               11 : base film or release film 
               12 : pressure-sensitive adhesive layer 
               12   a : first layer 
               12   b : second layer 
               13 : metal layer 
               21 : substrate 
               22 : organic electronic device 
           
         
       
     
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0104]    Hereinafter, the present application will be described in further detail with reference to examples according to the present application and comparative examples not according to the present application, and the scope of the present application is not limited to the following examples. 
       Example 1 
       [0105]    A coating solution was prepared by adding 50 g of butyl rubber (Br068, EXXON) as a polymer derived from butylene, 24 g of a hydrogenated hydrocarbon resin (Eastotac H-100L) as a tackifier, 15 g of trimethylolpropane triacrylate as a multifunctional active energy ray polymerizable compound, and 1 g of 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651, Ciba) as a radical initiator, and diluting the resultant mixture with toluene to have a solid content of about 15 wt %. 
         [0106]    An encapsulation film was formed by forming a pressure-sensitive adhesive layer to a thickness of 50 μm by coating a release surface of a release PET with the prepared solution and drying the coated product in an oven at 100° C. for 15 minutes, and laminating the pressure-sensitive adhesive layer with a copper film having a thickness of 20 μm. The film sample was irradiated with UV rays at 2 J/cm 2  to measure physical properties. 
       Example 2 
       [0107]    An encapsulation film was formed by the same method as described in Example 1, except that 10 g of a multifunctional active energy ray polymerizable compound was added. 
       Example 3 
       [0108]    An encapsulation film was formed by the same method as described in Example 1, except that 10 g of trimethylolpropane triacrylate as a multifunctional active energy ray polymerizable compound and 15 g of a monofunctional acrylate, i.e., 2-(2-ethoxyethoxy)ethyl acrylate as the compound of Formula 1 were added. 
       Comparative Example 1 
       [0109]    200 g of a silane-modified epoxy resin (KSR-177, Kukdo Chemical Co. Ltd.) and 150 g of a phenoxy resin (YP-50, Tohto Kasei Co. Ltd.) were added to a reactor at room temperature, and the resultant mixture was diluted with methylethylketone. A coating solution was prepared by adding 4 g of imidazole (Shikoku Kasei Co. Ltd.) as a curing agent to the homogenized solution, and stirring the resultant solution at a high speed for 1 hour. 
         [0110]    The prepared solution was applied to the releasing surface of a release PET, and dried in an oven at 100° C. for 15 minutes, thereby forming a pressure-sensitive adhesive layer having a thickness of 50 μm, and then the pressure-sensitive adhesive layer was laminated with a copper film having a thickness of 20 μm, resulting in an encapsulation film. The film sample was irradiated with UV rays at 2 J/cm 2  to measure physical properties. 
       Comparative Example 2 
       [0111]    A coating solution was prepared by adding 50 g of butyl rubber (Br068, EXXON) as a polymer derived from butylene, 24 g of a hydrogenated hydrocarbon resin (Eastotac H-100L) as a tackifier, 15 g of a monofunctional acrylate, i.e., stearyl acrylate, and 1 g of 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651, Ciba) as a radical initiator, and diluting the resultant mixture with toluene to have a solid content of about 15 wt %. 
         [0112]    An encapsulation film was formed by forming a pressure-sensitive adhesive layer to a thickness of 50 μm by coating a release surface of a release PET with the prepared solution and drying the coated product in an oven at 100° C. for 15 minutes, and laminating the pressure-sensitive adhesive layer with a copper film having a thickness of 20 μm. The film sample was irradiated with UV rays at 2 J/cm 2  to measure physical properties. 
       Comparative Example 3 
       [0113]    An encapsulation film was manufactured by the same method as described in Example 1, except that 60 g of butyl rubber (Br068, EXXON) as a polymer derived from butylene, 20 g of a hydrogenated hydrocarbon resin (Eastotac H-100L) as a tackifier, and 32 g of trimethylolpropane triacrylate as a multifunctional active energy ray polymerizable compound were added. 
       Experimental Example 1 
     Measurement of Viscosity 
       [0114]    The Mooney viscosity of the pressure-sensitive adhesive prepared in each of Examples and Comparative Examples was measured through ARES produced by TA. The Mooney viscosity was measured according to a shear stress using a planar jig having a diameter of 8 mm at a strain of 5%, a frequency of 1 Hz and a temperature of 30° C., and additionally measured at 100° C. 
       Experimental Example 2 
     Tool Fouling and Panel Laminating Property 
       [0115]    The pressure-sensitive adhesive layer having a thickness of 50 μm and a size of 14 cm×9 cm, which was formed in any one of Examples and Comparative Examples, was attached to the center of a 0.7 T glass having a size of 150 cm×10 cm using a roll laminator. A glass having the same size as the prepared specimen was laminated by vertical pressing using a vacuum laminator at 25 to 100° C. and a vacuum degree of 100 pa under a pressure of 0.5 MPa. 
         [0116]    A laminating property was determined by the degree of non-lamination or bubble generation on the entire surfaces of a pressure-sensitive adhesive, and thus when non-lamination or generation of at least one bubble having a diameter of 3 mm or more occurred, it was determined as a lamination failure. 
         [0117]    Also, when the pressure-sensitive adhesive layer having a size of 14 cm×9 cm was laminated, and spilled on a side surface 300 μm away from the original size, a tool was fouled in a panel process. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 30° C. 
                 100° C. 
                   
                   
               
               
                   
                 viscosity 
                 viscosity 
                 Tool 
                 Panel laminating 
               
               
                   
                 (Pa · s) 
                 (Pa · s) 
                 fouling 
                 property 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Example 1 
                  7,000 
                 5,200 
                 No 
                 Excellent 
               
               
                 Example 2 
                  12,000 
                 980 
                 No 
                 Excellent 
               
               
                 Example 3 
                 170,000 
                 150,000 
                 No 
                 Excellent 
               
               
                 Comparative 
                 1.8 × 10 7   
                 700 
                 Yes 
                 Lamination failed 
               
               
                 Example 1 
               
               
                 Comparative 
                 2.5 × 10 7   
                 400 
                 Yes 
                 Excellent 
               
               
                 Example 2 
               
               
                 Comparative 
                 2.5 × 10 7   
                 2.5 × 10 7   
                 No 
                 Lamination failed 
               
               
                 Example 3