HK1121581A - Radiation curable cycloaliphatic barrier sealants - Google Patents

Description

Radiation curable cycloaliphatic barrier sealants

[0001] The invention was made with U.S. government support under the protocol number MDA972-93-2-0014, granted by the Army Research Laboratories. The government has certain rights in the invention.

Technical Field

[0002] The present invention relates to impervious adhesives, sealants, encapsulants and coatings for electronic and optoelectronic devices. (As used in this specification and claims, adhesives, sealants, encapsulants and coatings are analogous substances, all having the properties and function of adhesives, sealants, encapsulants and coatings

Background

[0003] For reasons including: low energy consumption during curing, fast curing speed by free radical and cationic mechanisms, low curing temperature, wide availability of curable materials and the utility of solvent-free products, radiation curable materials have been increasingly used as coatings, adhesives and sealants over the last three decades. These advantages make such products particularly suitable for rapidly bonding and sealing electronic and optoelectronic devices that are temperature sensitive or cannot conveniently withstand long term curing. In particular, optoelectronic devices are often heat sensitive and may require optical alignment and spatial fixturing by curing in a very short time.

[0004] Many optoelectronic devices are also moisture or oxygen sensitive, which requires that exposure be avoided during the operational lifetime. The usual method is to seal the device between an impermeable substrate on which the device is placed and an impermeable glass or metal cover using a radiation curable adhesive or sealant, and to seal or bond the perimeter of the cover to the base substrate.

[0005] The general form of the package geometry is exemplified in fig. 1, which illustrates: a metal or glass lid (2) is bonded to a glass substrate (4) over an Organic Light Emitting Diode (OLED) stack (3) fabricated thereon using a radiation curable perimeter sealant (1). Although there are many configurations, a typical device also includes an anode (5), a cathode (6), and some form of electrical interconnection between the OLED pixel (pixel)/device and external circuitry (7). For the purposes of the present invention, no particular device geometry is specified or required other than the addition of the adhesive/sealant material, such as the perimeter sealant (1).

[0006] In many configurations, such as the example of fig. 1, both the glass substrate and the metal/glass cover are substantially impermeable to oxygen and moisture, and the sealant is the only material surrounding the device with any measurable permeability. For electronic and optoelectronic devices, moisture permeability is more often more important than oxygen permeability; therefore, the oxygen permeation resistance requirements are much less stringent, and the moisture barrier property of the perimeter sealant (or moisture permeation resistance) is critical for good device performance.

[0007] A good barrier sealant (barrier sealant) will exhibit low bulk moisture permeability (bulk moisture permeability), good adhesion, and strong adhesive/substrate interface interaction. If the quality of the interface between the substrate and the sealant is not good, the interface may become a weak edge, causing moisture to rapidly enter the device regardless of the overall moisture permeability of the sealant. If the interface is at least as continuous as the overall sealant, the permeability to moisture is generally determined by the overall moisture permeability of the sealant itself.

[0008] It is important to note that moisture permeability (P) must be measured to measure effective barrier properties, not just Water Vapor Transmission Rate (WVTR), since the latter is not normalized to a defined permeation path thickness or path length. Generally, permeability can be defined as WVTR multiplied by unit permeation path length, and thus is the preferred method of evaluating whether a sealant is inherently a good barrier material.

[0009]The most common way to express permeability is the permeability coefficient (e.g., g.mil/(100 in)²Day atm)), applied under any experimental conditions, or permeability coefficient (e.g., g.mil/(100 in) at a given temperature and relative humidity²Days)), which must quote the experimental conditions to define the partial pressure/concentration of the permeant present in the barrier material. In general, the penetration force (permeability, P) of a permeant through a barrier material can be expressed as the product of a diffusion term (D) and a solubility term (S): p ═ DS.

[0010]The solubility term reflects the affinity of the barrier material for the permeant, and for water vapor, a low S term is obtained for hydrophobic materials. The diffusion term measures the mobility of the permeant in the barrier matrix and is directly related to the material properties of the barrier, such as free volume and molecular mobility. Generally, a low D term results from a highly crosslinked or crystalline material (as opposed to a less crosslinked or amorphous analog). When the molecular motion increases (e.g. when the temperature rises, especially when the T of the polymer increases_gToo high), the permeability will increase dramatically.

[0011] A rational chemical method for producing improved barrier materials must consider these two fundamental factors (D and S) that affect the water vapor and oxygen permeability. Added to these chemical factors are physical variables: long permeation paths and flawless tie layers (good wetting of the adhesive on the substrate) which improve the performance of the barrier material should be applied whenever possible. The ideal barrier sealant will exhibit low D and S terms while providing excellent adhesion to all device substrates.

[0012] To obtain a high performance barrier material, it is not sufficient to have only a low solubility (S) term or only a low diffusivity (D) term. Typical examples can be found in conventional silicone elastomers. This material is extremely hydrophobic (low solubility term, S), however, it is a rather poor barrier material due to the high molecular mobility due to the unrestricted rotation of its Si-O bond, which produces a high diffusivity term (D). Thus, many systems that are merely hydrophobic are not good barrier materials, despite their exhibiting low water solubility. Low water solubility must be combined with low molecular mobility, thereby resulting in low permeate mobility or diffusivity.

[0013] For liquid materials that can be radiation or thermally cured into solid sealants, such as the present compositions, lower molecular mobility is achieved in the cured matrix through high crosslink density, microcrystallinity, or close packing of the molecular backbone between the crosslinking portions of the matrix.

Brief Description of Drawings

[0014] FIG. 1 is a depiction of a perimeter sealed optoelectronic device; FIG. 2 is a depiction of the synthesis of cycloaliphatic vinyl ethers; FIG. 3 is a PhotoDSC analysis of the basic Q43/TAIC thiol-ene system (formulation 7); and FIG. 4 is a real-time UV-FT-IR analysis of a basic Q43/TAIC thiol-ene system (formulation 7).

Summary of The Invention

[0015] The present inventors have discovered that certain resins and resin/filler systems provide superior barrier properties by incorporating radiation curable materials having cycloaliphatic backbones. The cycloaliphatic barrier material may be used alone or in combination with other resins and various fillers. The final composition exhibited a commercially useful cure speed; a balance of high crosslink density, stiffness, and molecular packing (low permeate mobility/diffusivity term D); hydrophobic (low water solubility term S); and adhesion capability (strong adhesive/substrate interface), making it useful for sealing and encapsulating electronic, optoelectronic and MEMS devices.

Detailed Description

[0016] The references cited herein are incorporated by reference in their entirety. The present invention is a curable barrier adhesive or sealant comprising: (a) a curable resin characterized by having (i) an alicyclic (or alicyclic) backbone, and (ii) at least one reactive functional group present in an amount of 400 grams or less of its equivalent weight per mole of reactive functional group; and (b) an initiator. The expression "at least one reactive functional group" means one or more reactive functional groups of the same type and/or one or more types; the total functional group equivalent will be kept below 400 grams per mole. In another embodiment, the radiation curable barrier adhesive or sealant further comprises (c) a reactive or non-reactive resin (other than a resin having a cycloaliphatic backbone). In a further embodiment, the curable barrier adhesive or sealant further comprises (d) a filler. Radiation curable sealants are generally preferred (the reasons for which are already explained in the background section), but heat curable sealants are also useful depending on the particular application.

[0017] In this specification, the term "radiation" is used to describe actinic electromagnetic radiation. Actinic radiation is defined as electromagnetic radiation that causes a chemical change in a substance and, for purposes of this specification, also includes electron beam curing. In most cases, electromagnetic radiation having wavelengths in the Ultraviolet (UV) and/or visible region spectrum is most useful.

[0018]In the present specification, the term "alicyclic OR alicyclic" (cycloaliphatic) generally refers to a class of organic compounds containing carbon and hydrogen atoms joined to form one OR more rings, which may contain other atoms, such as halogens (e.g., chlorine, bromine, iodine), heteroatoms (e.g., oxygen, sulfur, nitrogen), OR substituents (e.g., OR, SR, NR)₂Wherein R is a linear or branched alkyl or cycloalkyl or aryl group). Generally, a cycloaliphatic resin is defined as a resin whose backbone contains a cyclic carbocyclic structure, which may contain heteroatoms within or attached to the backbone. Preferably, the cycloaliphatic resin backbone consists essentially of carbon, hydrogen, and halogen atoms. The cycloaliphatic radiation curable resin (a) may be a small molecule, oligomer or polymer depending on its desired end use application and material properties.

[0019] Suitable resins comprising a cycloaliphatic backbone are any resin which, when crosslinked, allows for the close packing of relatively rigid molecular segments between the crosslinked portions of the matrix. (these molecular fragments are derived from an uncured cycloaliphatic backbone.) the cycloaliphatic molecule has the general structure represented by:

wherein L is a linking group each independently selected from the group consisting of:

and

r is a linear or branched alkyl, cycloalkyl, aryl, heteroaryl, silane or siloxane and may contain heteroatoms (such as oxygen, sulfur and nitrogen); x is a reactive group independently selected from the group consisting of epoxy, selected from the group consisting of glycidol epoxy, aliphatic epoxy, and cycloaliphatic epoxy; acrylates and methacrylates; itaconate esters; a maleimide; ethers of vinyl, propenyl, butenyl, allyl and propargyl and thioethers of these groups; maleates, fumarates and cinnamates; styrenes; acrylamide and methacrylamide; a chalcone; a thiol; allyl, alkenyl, and cycloalkenyl; n, k and l equal to 0 or 1; y is equal to 1 to 10. In one embodiment, the reactive group X on the radiation curable resin is a vinyl ether, an acrylate or a methacrylate.

[0020] Particularly suitable compounds having a cycloaliphatic backbone are selected from:

wherein X is a reactive group independently selected from the group consisting of epoxy, selected from the group consisting of glycidol epoxy, aliphatic epoxy, and cycloaliphatic epoxy; acrylates and methacrylates; itaconate esters; a maleimide; ethers of vinyl, propenyl, butenyl, allyl and propargyl and thioethers of these groups; maleates, fumarates and cinnamates; styrenes; acrylamide and methacrylamide; a chalcone; a thiol; allyl, alkenyl, and cycloalkenyl; r is hydrogen, alkyl or halogen; r₁Is a linear or branched alkyl or cycloalkyl group and may contain heteroatoms, and z ═ 0 or 1.

[0021] When n, k, and l are 0in the above structure and X is in the form of an epoxy, X may be attached to the cycloaliphatic backbone by a direct bond or may be part of the cycloaliphatic backbone. Other suitable compounds include those selected from the following structures:

and

wherein R is hydrogen, alkyl, heteroalkyl, or halogen. Further examples of suitable resins include dicyclopentadiene (DCPD) dimethylol diacrylate and cycloaliphatic vinyl ethers derived from DCPD dimethylol as shown in FIG. 2.

Other suitable radiation curable resins having a cycloaliphatic backbone are those selected from the group consisting of:

and

[0022]in one embodiment, the cured resin of the moisture barrier sealant is a moisture barrier sealantWherein R is hydrogen, alkyl (e.g., methyl), or halogen (e.g., chlorine). In another embodiment, the cured resin of the moisture resistant sealant isWherein R is hydrogen, alkyl (e.g., methyl), or halogen (e.g., chlorine).

[0023] As mentioned above, suitable curable functional groups on the resin (a) include any group known to those skilled in the art of UV and thermally curable materials and filled polymer compositions. Conventional curable functional groups include, but are not limited to: an epoxy selected from the group consisting of glycidyl epoxies, aliphatic epoxies, and cycloaliphatic epoxies; acrylates and methacrylates; itaconate esters; a maleimide; ethers of vinyl, propenyl, butenyl, allyl and propargyl and thioethers of these groups; maleates, fumarates and cinnamates; styrenes; acrylamide and methacrylamide; a chalcone; a thiol; allyl, alkenyl, and cycloalkenyl. The mechanism of polymerization after irradiation or heating is not limited, but is generally a radical or cationic process. The inventors have found that within a predefined range of total crosslink density, the type of reactive functional groups present is less important for barrier properties than the backbone nature to which they are attached.

[0024] The reactive functionality will be present at a level of equivalent weight of 400 grams or less per mole of reactive functional group. The definition of equivalents is a definition commonly used by those skilled in the art: i.e., molecular weight divided by total functionality (e.g., epoxy, acrylate, maleimide, etc.). Equivalents are mass per mole of active group. Generally, low equivalent weight molecules are highly functional and provide a highly crosslinked matrix after curing (assuming good conversion after curing).

[0025]In general, highly crosslinked materials (low uncured equivalent weight) yield rigid, high glass transition temperatures (T)_g) Low free volume material. The inventors understand that this is not a universal relationship, and that the properties of the parent also have an effect on the free volume. For example, non-uniform cross-linking or microporosity may result in simpler T_gThe unexpectedly high free volume of the relationship. However, the inventors have demonstrated that highly crosslinked materials tend to produce better barrier materials when other factors remain unchanged. However, as shown in the examples, a high crosslinking density alone does not guarantee good barrier properties.

[0026] It is also beneficial if the permeant has low solubility in the barrier material. Relative to moisture, if the barrier material is hydrophobic, this results in low moisture solubility in the cured adhesive/sealant barrier material, which reduces moisture permeability. Hydrophobic materials, in contrast, are not necessarily good barrier materials, especially if they have a low crosslink density (high uncured equivalent weight) or exhibit high mobility/high free volume in the cured state. In the present specification, the term hydrophobic means absorbing 5.00% by weight or less of water under the conditions of 85 ℃ and 85% Relative Humidity (RH).

[0027] The inventors have discovered that certain cycloaliphatic backbones, those having low functional group equivalents, can provide low uncured viscosities while being effectively stacked in radiation or thermal curing systems. This packing of backbone molecules, combined with the high crosslink density provided by the low functional group equivalent weight, results in low cured matrix mobility and thus low permeant mobility.

[0028] In addition, cycloaliphatic based compositions tend to be hydrophobic in that they are predominantly hydrocarbon in nature. This hydrophobicity results in low moisture solubility in the cured material, which also reduces moisture permeability. The use of a primary cycloaliphatic material to achieve this combination of low permeability mobility and low moisture solubility is novel and unexpected in curable barrier materials.

[0029] Suitable radiation curable resins and photoinitiators for suitable radiation curable resins may be those generally described in the open literature. Representative examples can be found in literature sources such as Fouassier, J-P., Photoionization and photoconversion fuels and Applications 1995, Hanser/Gardner publications, Inc., New York, NY. Chapter sixth is a particularly useful overview of the various radiation curable resins and photoinitiators used by those skilled in the art. Exemplary photoinitiators are disclosed in Ionic polymers and Related processes, 45-60, 1999, Kluwer Academic Publishers; netherlands; puskas et al (eds.). The curing mechanism may be any of those described therein, while the most common resin systems cure by a free radical or cationic mechanism.

[0030] For radiation curable sealants, the initiator (b) will be a photoinitiator. The photoinitiators (b) of the radiation curable barrier adhesives of the present invention are well known to those skilled in the art of radiation curing. The selection of a suitable photoinitiator system will depend in large part on the particular application for which the barrier sealant is used. One suitable photoinitiator is one that exhibits a different light absorption spectrum than the resins, fillers, and other additives in the radiation curable system. If the sealant must be cured through the cover or substrate, the photoinitiator will be one that is capable of absorbing radiation at wavelengths that are transparent to the cover or substrate. For example, if the barrier sealant is to be cured by a soda lime glass cover sheet, the photoinitiator must have significant absorption above about 320nm, which is the Ultraviolet (UV) cut-off wavelength (UV cut-off) of soda lime glass. In some cases, it is expected that the use of photosensitizers will be helpful.

[0031] Generally, for systems that cure via a free radical mechanism, either type I (dissociative) or type II (H-extractable) free radical photoinitiators may be used. Small molecule, high molecule, or polymerizable photoinitiators may be used. For many applications, common dissociative photoinitiators, such as those supplied by Ciba Specialty Chemicals, are useful. Preferred photoinitiators include Irgacure651, Irgacure 907 and Irgacure 819, all of the Ciba products. Alternatively, one preferred class of photoinitiators is polymer-bound aromatic ketones, or polymeric type II photoinitiators. Such systems do not produce small molecular photo-byproducts and thus tend to produce less odorous, degassed and extractable components after uv curing. Such systems may or may not require photosensitizers depending on the particular application and resin system used.

[0032] Preferred cationic photoinitiators include diaryliodonium salts and triarylsulfonium salts. Well known commercially available examples include UV9380C (GE Silicones), PC2506(Polyset), Rhodorsil 2074(Rhodia) and UVI-6974 (Dow). If cured through a certain cover or substrate, a suitable photosensitizer should be used to ensure sufficient light absorption by the photoinitiating system. Preferred photosensitizers for diaryliodonium salts are isopropylthioxanthone (usually sold as a mixture of 2-and 4-isomers) and 2-chloro-4-propoxythioxanthone. The selection of effective cationic photoinitiating systems for specific curing geometries and resin systems is known to those skilled in the art of cationic UV curing and is not intended to limit the scope of the present invention.

[0033] Less common initiation systems, such as photogenerated bases (e.g., photogenerated amines or photogenerated polythiols) are also contemplated for use in situations where these basic catalysts, initiators, and curing agents are suitable.

[0034] The cycloaliphatic barrier adhesives of the present invention can be thermally and photochemically cured. Suitable thermal initiators are well known to those skilled in the art of thermosetting chemistry and vary widely depending on the type of resin, the curing mechanism, and the end use of the barrier sealant.

[0035] For free radical curing sealants, a number of free radical thermal initiators are available. Conventional examples include azo-type initiators such as 2, 2 '-azobisisobutyronitrile (available from various suppliers including Dupont sold as Vazo 64), peroxy ketals such as 1, l' -bis (£ amyl peroxy) cyclohexane (sold as USP-90MD by Witco), peresters such as f-amyl peroxypivalate (sold as Trigonox 125-C75 by Akzo), and alkyl peroxides such as dicumyl peroxide (available from various suppliers such as Witco).

[0036] A variety of thermal cationic initiators are also contemplated. Generally, these catalysts include any type of bronsted or lewis acid, often in the form of a latent thermal acid generator. Examples of latent heat acid generators include, but are not limited to, diaryliodonium salts, benzylsulfonium salts, phenacylsulfonium salts, N-benzylpyridinium salts, N-benzylpyrazine salts, N-benzylammonium salts, * salts, * salts, and ammonium borate salts. An example of a useful diaryliodonium salt thermal cationic initiator is PC2506 (Polyset). Diaryl iodonium salts can generally accelerate the reaction (causing it to initiate at low temperatures with acceptable latency) by the addition of an electron donating co-initiator such as benzopinacol. The initiation mechanism essentially becomes a redox of the diaryl iodonium salt by species generated by thermal decomposition of the coinitiator. Representative examples of other thermally activated cationic catalysts include sulfonic acid esters and sulfonic acid salts (available from King industries under the trade names Nacure and K-cure).

[0037] The cycloaliphatic resin component may optionally be mixed with one or more other reactive or non-reactive resin components (c). These optional resins may be used to modify specific properties of the composition, such as toughness, flexibility, adhesion to some substrates, or to minimize weight loss during or after curing. Typically, it is advantageous to use cycloaliphatic materials as is actually required. The amount of these other resin ingredients used will vary depending on the application, processing conditions and barrier requirements, but will generally be in the range of 1-90% of the total resin portion of the barrier sealant composition.

[0038] If the second (non-cycloaliphatic) resin component is reactive, it may contain any of the reactive groups of the cycloaliphatic resin component described above. Thus, commonly reactive alternative resins include, but are not limited to, epoxy resins, acrylic resins, maleimide resins, vinyl and propargyl ether resins, fumarates, maleates, cinnamates, chalcones, polythiols, and allylated molecules.

[0039]Representative epoxy resins are glycidyl ethers and cycloaliphatic epoxy resins. Numerous sources and variations of glycidyl ethers are familiar to those of ordinary skill in the art. Representative aromatic liquid glycidyl ethers include epoxy resins such as Epikote 862 (predominantly bisphenol F diglycidyl ether) or Epikote 828 (predominantly bisphenol A diglycidyl ether). Preferred solid glycidyl ethers include Epon 1031, Epon 164, SU-8, DER 542 (brominated bisphenol A diglycidyl ether), RSS 1407 (tetramethyldiphenyl glycidyl ether), and Erisys RDGE (resorcinol diglycidyl ether). All of these Epikote^®And Epon^®Glycidyl ethers are available from Resolution Performance Products. Erisys EDGE^®Available from CVC specialty chemicals inc. Representative non-aromatic glycidyl epoxy resins include EXA-7015 (hydrogenated bisphenol A diglycidyl ether), available from Dainippon Ink&Obtained from Chemicals. Representative cycloaliphatic epoxy resins include ERL 4221 and ERL 6128, available from Dow chemical co.

[0040] Representative vinyl ether molecules such as Rapicure-CHVE (cyclohexane dimethylol divinyl ether), Rapicure-DPE-3 (tripropylene glycol divinyl ether) or Rapicure-DDVE (dodecyl vinyl ether) are readily available from International Specialty Products. Similar vinyl ethers are also available from BASF. Vinyl ether terminated polyurethanes and polyesters are available from Morflex. Reactive unsaturated polyesters are available from Reichold. Many types of acrylate monomers, oligomers, and polymers are available from distributors such as sartomer corporation and may be used as reactive resin additives. These include a number of mono-or multifunctional acrylic monomers, acrylated polyurethanes, acrylated polyesters and metal diacrylates. Acrylated silicones are available from Gelest and others.

[0041]Optional fillers (d) can vary widely and are well known to those skilled in the art of composites. Typical fillers include, but are not limited to, quartz powder, fused silica, amorphous silica, talc, glass beads, graphite, carbon black, alumina, clay, mica, vermiculite, aluminum nitride, and boron nitride. Metal powders and metal flakes containing silver, copper, gold, tin/lead alloys and other alloys are contemplated. Organic filler powders such as poly (tetrachloroethylene), poly (chlorotrifluoroethylene), and poly (vinylidene-1, 1-dichloroethylene) may be used. Fillers used as moisture scavengers or oxygen scavengers, including, but not limited to, CaO, BaO, Na₂SO₄、CaSO₄、MgSO₄Zeolite, silica gel, P₂O₅、CaCl₂And Al₂O₃May also be used.

Examples

[0042] Example 1 UV curable cycloaliphatic acrylic Barrier Material

[0043] Several UV-curable acrylate compositions were formulated from several structurally different acrylic resins with polythiols, photoinitiators, and fused silica in the weight fractions shown in Table 1.

[0044]

TABLE 1 UV-CURABLE ACRYLATE FORMULATIONS
						Recipe number	Parts of acrylate resin	Acrylate equivalent weight (g/mol)	Number of polythiols	Parts of photoinitiator	Fused silica fraction
1	89.3HDDA(SR238)	113	3.8	1.9	5.0
						2	89.3TMPTA(SR351)	148	3.8	1.9	5.0
3	89.3DCPDDA(SR833)	152	3.8	1.9	5.0
						4	94.0pBDDMA(CN 301)	～1400	4.0	2.0	0

[0045] HDDA is hexanediol diacrylate; TMPTA is trimethylolpropane triacrylate; pBD DMA is poly (butadiene) dimethacrylate; DCPDDA is dicyclopentadiene dimethylol diacrylate.

[0046] Q-43 is pentaerythritol tris (3-mercapto-propionate), a polythiol which acts as an oxygen reduction inhibitor and as a toughening agent. The Q-43 polythiol has the following structure:

[0047] the photoinitiator used was Irgacure651, obtained from Ciba Specialty Chemicals. Fused silica acts as a thixotropic agent to allow high quality films to be formed and purged with nitrogen prior to curing without de-wetting the release liner substrate.

[0048] The resin components of the formulation were mixed and magnetically stirred until the photoinitiator dissolved. Fused silica was added and briefly hand mixed, followed by three passes in a three-roll mill. After milling, no particles larger than 10 μm were observed in the Hegeman metering test. Formulation 4 does not require a fused silica thixotropic agent because it has a higher viscosity than other formulations.

[0049]On release coated Mylar substratesA drawdown film (drawdown film) of these filled formulations was produced. These films were placed in a flow-through chamber and purged with nitrogen for 3 minutes, followed by uv curing on a Dymax fixed curing apparatus. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. The cured film was then removed from the release Mylar substrate. The equilibrium overall moisture permeability coefficient was measured using a Mocon Permatran-W3/33 instrument at 50 deg.C/100% Relative Humidity (RH). The results are shown in Table 2.

[0050]

TABLE 2 moisture permeability coefficient of acrylate formulations
				Recipe number	Acrylate resin	Acrylate equivalent weight	Moisture permeability coefficient (at 50 ℃/100% relative humidity g.mil/100in2Day of the year])
1	HDDA	113	39.7
				2	TMPTA	148	18.5
3	DCPDDA	152	8.7
				4	pBD DMA	～1400	92.7

[0051] From this simple embodiment, several important concepts can be noted. First, the three resin systems 1 to 3 are low equivalent weight and therefore are expected to produce highly crosslinked materials upon curing. However, the cycloaliphatic resin-based system (formulation 3) exhibited significantly lower overall penetration capacity than the other two acrylate formulations (formulations 1 and 2). Moreover, both HDDA (formulation 1) and DCPDDA (formulation 3) are considered hydrophobic acrylate materials (TMPTA, formulation 2, also quite hydrophobic), however the cycloaliphatic resin provides superior moisture barrier properties as well.

[0052] Films based on a poly (butadiene) backbone (formulation 4) exhibit the highest moisture permeability at present. This suggests that, despite the extremely strong hydrophobic character of the poly (butadiene) backbone of pBD DMA, the low crosslink density of the membrane results in high molecular mobility and high permeability coefficient. Hydrophobicity alone does not result in a good barrier material.

[0053] Thus, while the HDDA, TMPTA and pBD DMA molecules all exhibit some properties that one would expect to produce good moisture resistance, these properties are not merely hydrophobic or merely high crosslink density, but rather a unique combination of backbone structure/packing and high crosslink density that gives DCPDDA-based formulation 3 a significantly superior moisture resistance.

[0054] Example 2 UV curable cycloaliphatic thiol-ene Barrier Material

[0055] Several UV curable thiol-ene formulations were formulated according to Table 3 using the same polythiol (Q-43), various ene components, and photoinitiator as in example 1.

[0056]

TABLE 3 UV curable cycloaliphatic thiol-ene barrier materials and UV curing
								Formulation of
5	6	7	8	9	10
						Q-43 parts by weight of mercaptan		34	43	60	60	53	53
DAC olefins parts by weight	65	41
						TAIC olefin parts by weight			14	39	39
TABPA alkene weight fraction					45		45
						Parts by weight of photoinitiator		1	2	1	1	2	2
Ultraviolet dose J UVA/cm2	3	3	3	3	3		3
						Thermal shock			10 minutes at 70 DEG C		10 minutes at 70 DEG C		10 minutes at 70 DEG C
Enthalpy of photopolymerization J/G	-150		-231		-117
						Time to maximum heat release (seconds)		4.0		4.0		2.4

[0057] Q-43 is pentaerythritol tetrakis (3-mercaptopropionate); DAC is diallyl chloroformate; TAIC is triallyl isocyanurate (containing 100ppm of BHT stabilizer); TABPA is tetraallylbisphenol A.

[0058] The structure of the polyene is:

[0059] the photoinitiator was Irgacure651, available from Ciba Specialty Chemicals, and was used in the appropriate amounts for each formulation.

[0060]The scratch films of each formulation were made on either an anti-stick coated Mylar substrate or directly on a PTFE coated aluminum plate. (some haze was noted in formulations 9 and 10). These films were uv cured in a Dymax fixed curing apparatus. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. The cured film is then removed from the anti-stick Mylar or PTFE coated sheet. In some of the cases shown, light thermal post-cure (thermal bump) is included in the curing procedure, as thiol-ene curing can be initiated by radiation or heat.

[0061]Attempts to achieve as near complete curing as possible, using light or mild heating, have been made in order to minimize the barrier property changes that may be caused by different degrees of conversion during curing. PhotoDSC analysis of the formulations showed that each formulation had a significant enthalpy of polymerization and low intensity conditions in PhotoDSC (1-10 mW/cm)²) The ultraviolet curing kinetics are good. The results for formulations 5, 7 and 9 are reported in table 3. Collected formulaRepresentative photoDSC and real-time FT-IR data for equation 7 are provided in fig. 3 and 4, respectively. The equilibrium overall moisture permeability coefficient was measured using a Mocon Permatran-W3/33 instrument at 50 deg.C/100% Relative Humidity (RH). The results are provided in table 4 below.

[0062]

TABLE 4 moisture permeability coefficient of thiol-ene systems
					Recipe number	Thiols	Alkene(s)	Remarks for note	Moisture permeability coefficient (50 ℃/100% RH g.mil/100 in)2Day of the year])
5	Q-43	DAC	UV curing only	14.4

6	Q-43	DAC/TAIC	UV + thermal shock	15.6
					7	Q-43	TAIC	UV curing only	16.0
8	Q-43	TAIC	UV + thermal shock	15.3
					9	Q-43	TABPA	UV curing only	47.5
10	Q-43	TABPA	UV + thermal shock	54.5

[0063] The best barrier properties were obtained in the case of alicyclic olefin applications when the thiol component was kept constant and the olefin component was changed (formulation 5). Formulations 6 and 7 demonstrate that the moisture permeability is steadily increased when the alicyclic olefin component is diluted (formulation 6) or replaced (formulation 7) with additional olefin (TAIC in this example).

[0064] Notably, the internal double bonds of DAC are not as reactive as allyl groups and therefore the trifunctional ene TAIC should produce a higher crosslink density than DAC, as indicated by the photoDSC exotherm. The data show that the formulations containing TAIC exhibit poorer moisture resistance than the formulations containing DAC, even though the formulations containing TAIC have a higher crosslink density than the DAC films when cured. The alicyclic nature of DAC alkenes is believed to play a role in this phenomenon, and chlorination of DAC may also contribute favorably to its moisture resistance.

[0065] The formulation using TABPA instead of DAC (formulation 9) also showed high moisture permeability compared to the DAC/Q-43 system (formulation 5). Thus, despite the fact that TABPA polyenes are very hydrophobic (due to lack of polar functionality) and have higher functionality than DAC (4vs.2-3), they are not sufficiently comparable to the moisture barrier properties obtained when using cycloaliphatic DAC polyenes. It is generally noted that the use of thermal post-cure (formulations 6, 8 and 10) did not slightly affect the moisture permeability or conclusions in the series of experiments as described previously.

[0066] EXAMPLE 3 epoxy/vinyl Ether UV curing mixture

[0067] Several formulations were prepared using the components and parts by weight listed in table 5 below. The photoinitiator was UV9380C, available from GE Silicones. The structure of the vinyl ether is as follows:

[0068]the components are mixed manually and then connectedFollowed by mixing in a DAC 150FV2-K (FlackTeck Inc.) high speed mixer at 3000rpm for 2 minutes. The resulting paste was coated on a release-coated PET film with a squeegee, and the formed wet film was uv-cured in a Dymax curing apparatus. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. The cured epoxy/vinyl ether film was removed from the PET backing and analyzed. The equilibrium bulk moisture permeability coefficient was measured using a Mocon Permatran-W3/33 instrument at 50 deg.C/100% Relative Humidity (RH).

[0069]

TABLE 5 Barrier sealants containing vinyl ether/epoxy blends
					Resin component	Formulation 11 (parts by weight)	Formula 12 (parts by weight)	Formula 13 (parts by weight)	Formula 14 (parts by weight)
Aromatic epoxy	56	56	56	56
					CAVE	37
CHVE		37
					BDDVE			37
DVE-3				37
					Photoinitiator	2	2	2	2
Fused silica	5	5	5	5

[0070]

TABLE 6 vinyl Ether component vs. moisture permeability
					Vinyl ether component	CAVE	CHVE	BDDVE	DVE-3
Vinyl ether equivalent weight	124.2	98.1	71.1	101.1

Recipe number	11	12	13	14
					Moisture permeability coefficient (50 ℃/100% RH [ g.mil/100 in)2Day of the year])	5.7	8.4	71.1	111.7

[0071] As can be seen from tables 5 and 6, the two formulations containing the cycloaliphatic vinyl ether component (formulations 11 and 12, CAVE and CHVE, respectively) exhibited the lowest moisture vapor transmission capability. These results are due to the unique combination of high crosslink density and packing of the alicyclic backbone of both formulations, except that both are hydrophobic curing materials.

[0072] Notably, butanediol divinyl ether (BDDVE) has a lower equivalent weight than dicyclopentadiene dimethylol divinyl ether (CAVE) or cyclohexane dimethylol divinyl ether (CHVE). Thus, its formulation with an aromatic epoxy (formulation 13) should exhibit a higher cured crosslink density relative to formulations derived from CAVE and CHVE (formulations 11 and 12, respectively). As a result of their similar chemical structures, CAVE, CHVE, and BDDVE should have similar hydrophobicity, as should their respective cure formulations. While all three formulations exhibited high crosslink density (low vinyl ether equivalent weight) and hydrophobicity, the formulations based on CAVE and CHVE, which are also cycloaliphatic, exhibited better moisture barrier properties. Thus, it is the unique combination of high crosslink density and cycloaliphatic backbone properties that produces superior barrier performance for a given hydrophobicity.

[0073] Although the combination of high crosslink density and hydrophobicity obtained from the use of BDDVE results in a product with moisture barrier properties, the additional alicyclic structure feature present in CAVE and CHVE provides an unexpected enhancement in barrier performance.

[0074] The fourth formulation containing methylene glycol divinyl ether (DVE-3, formulation 14) exhibited much higher moisture permeability, believed to be due to the hydrophilic nature of its backbone (and the higher water solubility created in the polymer matrix) and the flexibility/mobility of its polyether backbone (resulting in higher permeation diffusivity).

[0075] EXAMPLE 4 epoxy/cycloaliphatic vinyl ether based UV curable moisture resistant sealant composition

[0076] The UV curable barrier sealant for the disposable syringe was formulated under short wavelength-visible filtered irradiation using the components shown in Table 7.

[0077]

TABLE 7 epoxy/cycloaliphatic vinyl ether barrier sealants
		resin/Filler	Parts by weight
Liquid aromatic epoxy	18.91
		Alicyclic Vinyl Ether (CAVE)	12.61
Silane adhesion promoter	0.17
		Photoinitiator	1.17
Isopropyl Thioxanthone (ITX)	0.15
		Silicon dioxide	66.00
Fused silica thixotropic agent	1.00

[0078] The resin components are mixed and stirred to dissolve the ITX photosensitizer. Then, silica filler was added and mixed by hand until a damp mass was obtained. The paste was then ground on a three-roll mill at least 2 times, using a gap set to less than 0.5mil between the rolls. A lake is considered to be sufficiently ground when no particles greater than 10 μm are observed in the Hegeman metering test. The product is aged in the dark for at least 24 hours before testing the rheology or the properties of the test material.

[0079] The adhesive composition may be used to seal various types of optoelectronic devices in which substrates such as glass, metal or polymeric films are bonded. In this example, a small piece of soda-lime glass (die) was bonded to a soda-lime glass substrate to simulate a perimeter-sealed "glass-glass" OLED device. The adhesive was coated on a PTFE coated Al substrate and a doctor blade was used to form an approximately 4mil film. Glass pieces were placed on the wet film, removed, and then placed on a clean glass substrate with light pressure to simulate a "pick and place" robotic packaging process.

[0080]The sample was then inverted and irradiated with an ultraviolet lamp through the glass substrate to produce a cured glass-glass bond. Uv curing was performed in a Dymax curing unit. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. (similar samples can be assembled to simulate glass-metal bonding, also commonly used for encapsulating OLEDs and other optoelectronic devices.)

[0081] The physical properties of the uncured and cured formulations are shown below:

[0082]

TABLE 8 physical Properties of epoxy/cycloaliphatic vinyl ether barrier sealants
		Rheology: viscosity (. eta.) was measured at 25 ℃ on a Brookfield cone and plate viscometer using a CP-51 spindle	η 12,800cP at 10rpm and 38,000cP at 1prm
Thixotropic index: eta at 1 rpm/eta at 10rpm	3.0
		Water vapor permeability coefficient (P) (equilibrium Overall moisture permeability coefficient) at 50 ℃ and 100% phaseThe measurement is carried out at humidity by using a Mocon Permatran-W3/33 instrument	P＝3.0g.mil/100in2Day of the year
Adhesion was measured as the chip shear strength (DSS) at 25 ℃ using a 4mm x 4mm piece of uv-ozone cleaned soda lime glass placed on a uv-ozone cleaned soda lime glass substrate. The curing scheme is as follows: UV dose is 50mW/cm23J UVA under UVA; annealing without heat; one day at ambient conditions between cure and shear tests	DSS 38.7kg force (average mean difference 6.7kg)
		Cured film thermo-gravimetric analysis (TGA) weight loss was performed on 4mil thick film samples. The curing scheme is as follows: UV dose is 50mW/cm23J UVA under UVA; without thermal shock.	Weight loss: 0.15% at 40 ℃/1 hour; 0.21% at 70 ℃/1 hour; 0.32% at 100 ℃/1 hour.
Viscoelastic analysis the glass transition temperature (T) was measured using dynamic mechanical analysisg) And a Young's modulus (E'); stretched rectangular shape with a frequency of 10 Hz.	Tg＝110℃E′(25℃)＝5×109Pa (approximate)
		Saturated Water absorption is determined on thin film samples at 85 ℃ and 85% relative humidity	＜0.6wt.％

[0083]These properties reflect several advantages of the cycloaliphatic vinyl ether (CAVE) component of the uv curable barrier sealant formulation. In uncured products, CAVE is used as a material with low volatility and low odorLow viscosity multifunctional components (low formulation viscosity allows for high inorganic filler loading). In the cured state, CAVE contributes hydrophobicity (as evidenced by low saturated water absorption/weight gain at 85 ℃/85% RH), good crosslink density due to its low equivalent weight and versatility (as evidenced by its relatively high T of uv cured formulations)_gAnd excellent shear adhesion strength of the formulation), excellent uv activity (as evidenced by low TGA weight loss of the cured film), and an overall moisture permeability coefficient that is lower than currently available ambient sealant products known to the inventors. The improved moisture barrier properties are obtained due to the high crosslink density and rigid backbone of the material (low osmotic mobility) and the overall hydrophobicity of the composition (low osmotic solubility).

[0084] EXAMPLE 5 cycloaliphatic acrylic-based UV-curable moisture resistant sealant composition

[0085] The materials shown in table 9 were mixed to produce a free radical curable thiol-acrylate based moisture resistant adhesive:

[0086]

TABLE 9 mercaptan-acrylate barrier compositions
		resin/Filler	Parts by weight
DCPDDA	47
		Thiols, Q-43	2
Photoinitiator	1
		Talc filler	50

[0087] Diacrylate (DCPDDA), thiol (Q43) and photoinitiator (Irgacure651) were mixed and magnetically stirred to dissolve the photoinitiator. In this resin system, 50 parts by weight of talc was added as a filler. The resin/filler blend was hand mixed and then stirred in a DAC 150FV2-K (flacketec Inc.) high speed stirrer at 2000rpm for 1 minute and 300rpm for 1 minute.

[0088]The paste was applied to a release-coated PET film using a doctor blade, and the resulting wet film was placed in a chamber purged with nitrogen for 5 minutes before uv curing was performed. The film was cured in a Dymax stationary curing apparatus. The UV dose was 3J UVA/cm²Strength of about 45mWUVA/cm²As measured with an EIT pocket radiometer. The equilibrium bulk moisture permeability coefficient was measured using a Mocon Permatran-W3/33 instrument at 50 deg.C/100% Relative Humidity (RH). The permeability coefficient under these conditions was found to be 4.1g.mil/100in²Day, this indicates superior overall moisture barrier properties relative to typical uv curable acrylic materials.

[0089] The adhesive composition can be used to seal a variety of optoelectronic devices that are bonded to a substrate such as glass, metal, or polymer film. For example, a small piece of soda-lime glass was bonded to a soda-lime glass substrate to simulate a peripherally sealed "glass-glass" OLED device. The adhesive was applied to an Al substrate containing a PTFE coating and a blade was used to form an approximately 4mil film. A small piece of glass was placed on the wet film, removed, and then placed on a glass substrate with light pressure to simulate a "pick and place" packaging process.

[0090]The sample was then inverted and irradiated with an ultraviolet lamp through the glass substrate to produce a cured glass-glass bond. Uv curing was performed in a Dymax curing unit. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. The glass-to-glass chip shear strength of the cured composition was 21.6kg force (standard deviation 3.7 kg). Similar samples can be assembled to simulate glass-metal bonding, which is also common for encapsulating OLEDs and other optoelectronic devices.

[0091] Example 6 barrier Properties of UV curable liquid bismaleimide resin

[0092]Two free radical curable liquid bismaleimide based formulations were made using the components listed in table 10. When the particular photoinitiator was used (formulations 16 and 18), it was dissolved in the respective bismaleimide resin by magnetic stirring. A scratch film of the formulation was made on an anti-stick coated Mylar substrate or a PTFE coated aluminum plate. These films were uv cured in a Dymax curing apparatus. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. The cured film is then removed from the anti-adhesive Mylar or PTFE substrate. The equilibrium bulk moisture permeability coefficient was measured using a Mocon Permatran-W3/33 instrument at 50 deg.C/100% Relative Humidity (RH).

[0093]

TABLE 10 UV curable liquid bismaleimide repellentPermeable material
					Recipe number	Liquid bismaleimide	Maleimide equivalent (g/mol)	Photoinitiator	Moisture permeability coefficient at 50 ℃/100% RH [ g.mil/100in2Day of the year]
15	100 parts of BMI-1		Is free of	47.9
					16	98 parts of BMI-1		2 parts of Irgacure651	49.8
17	100 parts of BMI-4		Is free of	18.7
					18	98 parts of BMI-4		2 parts of Irgacure651	19.3

[0094] BMM has the following structure:

[0095] BMI-4 has the following structure:

[0096] from this simple comparison, it is clear that the low equivalent weight and high crosslink density of BMI-4 bismaleimide (formulation 18) produced superior barrier properties compared to the BM1-1 formulation with a lower crosslink density (formulation 16). This may be that the presence of the alicyclic backbone in the BMI-4 formulation also contributes to enhanced moisture barrier properties, although crosslink density may be the primary difference in these examples. It is not entirely clear why the cured films without photoinitiator (formulations 15 and 17) exhibited somewhat lower overall penetration capacity relative to similar formulations with free radical photoinitiator (formulations 16 and 18).

[0097] The inventors note that formulations containing a particular photoinitiator may polymerize/crosslink primarily by standard free radical chain polymerization mechanisms, whereas formulations not containing a particular photoinitiator are expected to polymerize/chain extend primarily by the [2+2] cycloaddition process. These two different polymerization mechanisms produce different cured matrices that are expected to exhibit different transmission rates due to differences in crosslink density and/or morphology. Mixed-form polymerizations are possible in both cases, but these details are not investigated further here and are of no importance for the basic conclusions mentioned above and the trend with regard to the moisture permeability in relation to the equivalent weight and the main chain structure.

[0098] EXAMPLE 7 aromatic epoxy/cycloaliphatic epoxy based UV curable moisture resistant sealant composition

[0099] The UV curable barrier sealant for disposable syringes was formulated under short wavelength-visible filtered irradiation using the components shown in Table 11.

[0100]

TABLE 11 aromatic epoxy/cycloaliphatic epoxy barrier sealants
		resin/Filler	Parts by weight
Liquid aromatic epoxy	42.59
		Limonene Dioxide (LDO)	8.00
Silane adhesion promoter	0.13
		Photoinitiator	1.00
Isopropyl Thioxanthone (ITX)	0.02
		Epoxy siloxane	2.67
Talc	45.59

[0101] The resin components are mixed and stirred to dissolve the ITX photosensitizer. The talc filler was added immediately and mixed by hand until a damp mass was obtained. The paste was then ground on a three-roll mill at least 2 times, using a gap set to less than 0.5mil between the rolls. The paste was considered to be well ground when no particles larger than 20 μm were observed in the Hegeman metering test. The product is aged in the dark for at least 24 hours before checking the rheology or checking the material properties.

[0102] The adhesive composition can be used to seal various types of optoelectronic devices in which a substrate such as glass, metal, or polymer film is bonded. In this example, a small piece of soda-lime glass was bonded to a soda-lime glass substrate to simulate a peripherally sealed "glass-glass" OLED device. The adhesive was coated on a PTFE coated Al substrate and a doctor blade was used to form an approximately 4mil film. Glass pieces were placed on the wet film, removed, and then placed on a clean glass substrate with light pressure to simulate a "pick and place" robotic packaging process.

[0103]The sample was then inverted and irradiated with an ultraviolet lamp through the glass substrate to produce a cured glass-glass bond. Uv curing was performed in a Dymax curing unit. The UV dose was 3J UVA/cm²Intensity of about 45mW UVA/cm²As measured with an EIT pocket radiometer. (similar samples can be assembled to simulate glass-metal bonds, which are also common for encapsulating OLEDs and other optoelectronic devices.)

[0104] Physical properties of the uncured and cured compositions were obtained as shown in table 12.

[0105]

TABLE 12 physical Properties of aromatic epoxy/cycloaliphatic epoxy Barrier sealants
		Rheology: viscosity (. eta.) was measured at 25 ℃ using a CP-51 spindle on a Brookfield cone and plate viscometer	Eta at 10rpm, 12,730cP, and eta at 1prm, 24,680cP
Thixotropic index: eta at 1 rpm/eta at 10rpm	1.9
		Water vapor permeability coefficient (P) (equilibrium Overall moisture permeability coefficient) was determined at 50 ℃ and 100% relative humidity using a Mocon Permatran-W3/33 instrument	P＝6.5g.mil/100in2Day of the year
Adhesion 4mm x 4mm ultraviolet-ozone cleaned soda lime glass chips on a soda lime glass substrate cleaned with UV-ozone at 25 c were measured as chip shear strength (DSS). The curing scheme is as follows: UV dose is 50mW/cm2UVA is 3J UVA; annealing without heat; left at ambient conditions for 24 hours between cure and shear tests	DSS 15.3kg force (2.9 kg standard deviation)
		Cured thin film thermogravimetric analysis (TGA) weight loss was measured on 4mil thick film samples. The curing scheme is as follows: UV dose is 50mW/cm23J UVA under UVA; without thermal shock.	Weight loss: 0.5% at 40 ℃/1 hour; 0.5% at 70 ℃/1 hour; 0.5% at 100 ℃/1 hour.
Viscoelastic analysis the glass transition temperature (T) was measured using dynamic mechanical analysisg) And a Young's modulus (E'); stretched rectangular shape with a frequency of 10 Hz.	Tg＝120℃E′(25℃)＝1.5×109Pa (approximate)
		Saturated Water absorption is determined on thin film samples at 85 ℃ and 85% relative humidity	1.0wt.％

Claims (34)

1. A curable barrier sealant comprising

(a) Curable resin, characterized in that

(i) Has an alicyclic main chain and a side chain,

(ii) having at least one reactive functional group present in an amount such that the equivalent weight is less than 400 grams per mole of reactive functional group, and

(b) and (3) an initiator.

2. The curable barrier sealant according to claim 1 wherein the curable resin has the general structure:

wherein

Each L is a linking group independently selected from the group consisting of:

each R is independently selected from the following groups: linear or branched alkyl, cycloalkyl, aryl, heteroaryl, silane and siloxane;

each X is independently selected from: glycidyl epoxies, aliphatic epoxies, and cycloaliphatic epoxies; acrylates and methacrylates; itaconate esters; a maleimide; ethers of vinyl, propenyl, butenyl, allyl and propargyl and thioethers of these groups; a maleate ester; fumarate and cinnamate; styrenes; acrylamide and methacrylamide; a chalcone; a thiol; allyl, alkenyl, and cycloalkenyl;

n, k and l equal to 0 or 1; and

y is equal to 1 to 10.

3. The curable barrier sealant according to claim 2 wherein the reactive group X on the radiation curable resin is a vinyl ether or an acrylate.

4. The barrier sealant according to claim 2 wherein the cycloaliphatic resin is selected from the group consisting of:

wherein

X is a reactive group independently selected from: glycidyl epoxies, aliphatic epoxies, and cycloaliphatic epoxies; acrylates and methacrylates; itaconate esters; a maleimide; ethers of vinyl, propenyl, butenyl, allyl and propargyl and thioethers of these groups; a maleate ester; fumarate and cinnamate; styrenes; acrylamide and methacrylamide; a chalcone; a thiol; propenyl, alkenyl and cycloalkenyl;

r is hydrogen, alkyl or halogen;

R₁is a linear alkyl, branched alkyl, or cycloalkyl group, and may contain heteroatoms, and z is 0 or 1.

5. The curable barrier sealant according to claim 4 wherein the curable resin is selected from the group consisting of:

wherein R is hydrogen, alkyl or halogen.

6. The curable barrier sealant according to claim 3 wherein the radiation curable resin is

Wherein R is hydrogen, alkyl or halogen.

7. The curable barrier sealant according to claim 6 wherein the curable resin is

8. The curable barrier sealant according to claim 3 wherein the curable resin is

Wherein R is hydrogen, alkyl or halogen.

9. The curable barrier sealant according to claim 8 wherein the curable resin is

10. The curable barrier sealant according to claim 5 wherein the cycloaliphatic resin is selected from the group consisting of:

and

11. the curable barrier sealant according to claim 5 wherein the curable resin is selected from the group consisting of:

wherein R is hydrogen, alkyl, heteroalkyl, or halogen.

12. The curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin that does not contain a cycloaliphatic backbone.

13. The curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler.

14. The curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone and (d) a filler.

15. The curable barrier sealant according to any one of claims 1 to 11 wherein the curable barrier sealant is radiation curable.

16. The curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin that does not contain a cycloaliphatic backbone and wherein the curable barrier sealant is radiation curable.

17. The curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler, and wherein the curable barrier sealant is radiation curable.

18. The curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin that does not contain a cycloaliphatic backbone and (d) a filler, and wherein the curable barrier sealant is radiation curable.

19. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11.

20. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 and wherein the curable barrier sealant is radiation curable.

21. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone.

22. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler.

23. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone and (d) a filler.

24. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin that does not contain a cycloaliphatic backbone, wherein the curable barrier sealant is radiation curable.

25. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler, wherein the curable barrier sealant is radiation curable.

26. An electronic or optoelectronic device sealed with a curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone and (d) a filler, wherein the curable barrier sealant is radiation curable.

27. An OLED sealed with the curable barrier sealant of any one of claims 1 to 11.

28. An electronic or optoelectronic device sealed with the curable barrier sealant according to any one of claims 1 to 11, wherein the curable barrier sealant is radiation curable.

29. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone.

30. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler.

31. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone and (d) a filler.

32. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin that does not contain a cycloaliphatic backbone, wherein the curable barrier sealant is radiation curable.

33. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (d) a filler, wherein the curable barrier sealant is radiation curable.

34. An OLED sealed with the curable barrier sealant according to any one of claims 1 to 11 further comprising (c) a resin free of cycloaliphatic backbone and (d) a filler, wherein the curable barrier sealant is radiation curable.