Rackgrnnnd of the Invention It is well known that coatings containing silane compounds, multifunctional acrylates and itaconic acid improve the gas, oil, and flavor barrier performance of organic polymer film substrates, (See, for example, PCT/BE98/00006, the US equivalent of which is US Serial No.

09/341, 253, filed July 15, 1999). Moreover, the adhesion of the coating to the film surface, as well as the improved barrier characteristics provided by the silane coating, are greatly enhanced by exposing the coated film to electron beam radiation.

These coatings represent a significant advance in the art. However, it has been observed that while the barrier properties of the prior art coatings are excellent in environments at relative humidities of 80% or less, their performance suffers significantly at relative humidities of 90% or more.

The present inventors have surprisingly discovered that the combination of a bis-silane, a multifunctional acrylate, an ethylenically unsaturated acid gives excellent gas barrier properties at low to moderate relative humidity values, as well as excellent gas barrier properties at very high relative humidity values of 90% or more. The key improvement is the addition of a bis-silane, which results in excellent barrier at humidities of greater than 90%.

While other patents teach the combination of a mono or multifunctional acrylate with an aminofunctional silane, none teaches the addition of the ethylenically unsaturated acid with an acrylate and bis-silane. For example, U. S. Patent No. 5, 368, 941 teaches a deformable, abrasion- resistant coating formulated from at least one multi-functional acrylate monomer, at least one aminofunctional silane, colloidal silica and at least one acrylate-terminated polyalkylene oxide, but does not teach the addition of an ethylenically unsaturated acid. The acrylate-terminated polyalkylene oxide helps prevent gelling of the coating composition during stripping and also imparts the composition with deformability, without sacrificing abrasion resistance.

Other useful barrier compositions are also described in U. S. Patent No. 5, 215, 822, which teaches a methanol solution of a vinyl benzyl amine silane (Dow Coming Corp. Z-6032), itaconic acid, and water ; coating this solution on a corona treated low density polyethylene film, drying, and then subjecting the coated film to electron beam radiation to graft the coating to the film surface and further improve the barrier properties of the silane coating. However, while this coating gives excellent gas barrier properties at low to moderate relative humidity values, the gas permeability increases drastically at very high relative humidity values.

Also, U. S. Patent No. 5, 434, 007 teaches a silane resin coated on a plastic film, where the silane resin is composed of a monofunctional acrylate and an aminofunctional silane. The composition does not utilize a free radical cure, nor does it incorporate the ethylenically unsaturated acid.

U. S. Patent Nos. 5, 260, 350 and 5, 374, 483 relate to a silicone coating composition which, when cured on a solid substrate either by ultraviolet or electron beam radiation, provides a transparent abrasion resistant coating firmly adhered thereon. The silicone coating is prepared by reacting at least one multifunctional acrylate monomer with an amino-organofunctional silane, mixing the modified silane with at least one acrylic monomer and thereafter adding colloidal silica. Again however, neither of these compositions teach the addition of an ethylenically unsaturated acid to achieve barrier properties.

JP (Kokai) publication 7-18221 published on January 20, 1995 teaches a surface treatment composition for gas barrier comprising an aminosilane and a compound having an aromatic ring or hydrogenated ring. The present invention is distinguishable, however, because it does not require the addition of cyclic compounds having an aromatic ring.

The present invention is distinguishable over each of the above cited prior art because none teach the combination of a bis-silane, multifunctional acrylate, and ethylenically unsaturated acid to achieve gas barrier properties.

Summary of the Invention The invention is a composition made by mixing in any order a multifunctional acrylate with a bis-silane and an ethylenically unsaturated acid to form a reaction product, optionally dissolved in a solvent wherein the multifunctional acrylate has a molecular weight of from about 100 to about 3000, and the bis-silane has the formula RlbX. 3-bSi-Z-SiX3-b Rlb wherein Z is R2NH (R2NH) pR2. In this formula each RI is preferably a hydrocarbon group having 1 to 10 carbon atoms, for example a saturated or unsaturated aliphatic or aromatic group, for example alkyl alkenyl or phenyl groups ; preferred groups are methyl and ethyl, the most preferred of which are methyl groups. Each X is an alkoxy group with 1 to 4 carbon atoms, a halogen atom, an oxime group or an acyloxy group, of these methoxy and ethoxy groups are preferred, the most preferred being methoxy groups. R2 may be a divalent hydrocarbon group having 1 to 12 carbon atoms, preferably each R2 has from 2 to 3 carbon atoms. Each b is from 0 to 3 but is most preferably 0, and p is 0 or 1.

The composition can be coated on a substrate, then optionally exposed to moisture and treated to initiate a free radical reaction. The composition can be applied to a variety of substrates used in packaging applications. The composition can be cured by further heating in the presence of moisture. The free radical reaction can be initiated not only by heating but by electron beam irradiation, ultraviolet radiation, gamma radiation, and/or heat and chemical free radical initiators.

A composition according to the present invention may be employed to provide a barrier layer which improves resistance of the material to transmission of gases and aromas therethrough. For example, a 30 micron uncoated biaxially oriented, corona treated polypropylene film is generally found to have a permeability to oxygen of 1250 cc/m2/day as measured at ASTM D3985-81 measured at 90% relative humidity. With the present coatings, the oxygen transmission rate of the same film can be reduced to less than 250 cc/m2/day as measured at 90% relative humidity. As used herein, the terminology"improved barrier"refers to a coating which can reduce oxygen transmission rate of the aforementioned uncoated polypropylene film from 1500 cc/m2/day to 250 cc/m2/day as measured at ASTM D3985-81 measured at 90% relative humidity.

Description of the Preferred Embodiments While the invention is susceptible of embodiment in many different forms there is described herein in detail preferred and alternate embodiments of the invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit and scope of the invention and/or claims of the embodiments illustrated.

Bis-silanes The key to the present invention is a bis-silane described by the general formula RlbX3-bSi-Z-SiX3-b Rlb wherein Z is R2NH (R2NH) pR2. In this formula each Rl is preferably a hydrocarbon group having 1 to 10 carbon atoms, for example a saturated or unsaturated aliphatic or aromatic group, for example alkyl alkenyl or phenyl groups ; preferred groups are methyl and ethyl, the most preferred of which are methyl groups. Each X is an alkoxy group with 1 to 4 carbon atoms, a halogen atom, an oxime group or an acyloxy group, of these methoxy and ethoxy groups are preferred, the most preferred being methoxy groups. R2 may be a divalent hydrocarbon group having 1 to 12 carbon atoms, preferably each R2 has from 2 to 3 carbon atoms. Each b is from 0 to 3 but is most preferably 0, and p is 0 or 1. The best results are obtained by use of compounds in which each X is a methoxy group, each R2 is a propylene group, b is 0, and p is 0, i. e. when the compound is bis- (gamma-trimethoxysilylpropyl) amine.

These materials may be referred to as disilylated secondary amines used in the present invention may be prepared by processes known in the art for example, as disclosed in US Patent Nos. 2, 832, 754, 2, 920, 095 and 5, 101, 055.

Multifunctional Acrylates The multifunctional acrylates of the present invention are defined as acrylates having, on average, greater than two functional acrylate groups per molecule and a molecular weight of from about 100 to about 3000. Multifunctional acrylates are preferred over monofunctional acrylates because monofunctional acrylates do not form flexible, crack free coatings as do the multifunctional acrylates. The majority of multifunctional acrylates commercially available can be used, but it is the smaller, more compact, i. e., proportionally more reactive acrylates that give the best results. The multifunctional acrylates are preferably selected from the group consisting of acrylated polyols with molecular weights of from about 150 to about 600 ; polyester urethane acrylates with molecular weights of from about 1000 to about 2000 ; polyether acrylates with molecular weights from 200 to 1500 ; polyurethane acrylates with molecular weights of from about 400 to about 2000 ; polyurea acrylates with molecular weights of from about 400 to about 2000 ; epoxy acrylates with molecular weights of from about 300 to about 1000 ; and mixtures of multifunctional acrylates thereof.

Most preferred acrylates are pentaerythritol tetraacrylate ; an acid functional acrylate ; polyester tetra acrylate ; polyether tetra acrylate ; an aliphatic urethane acrylate, Ebecryl@ 1290 ; ditrimethylolpropane tetra acrylate ; an ethoxylated trimethylol propane triacrylate, Ebecryl (E' 160. Other preferred acrylate include glycerol triacrylate, triacrylate ester of tris- [2-hydroxy- ethyl] isocyanurate, hexane dioldiacrylate, and dipentaerythritol hexacrylate. Ethoxylated and propoxylated versions of these acrylates may be used in this invention. These acrylates and methods of their production are well know in the art, and available commercially from such companies as UCB Radcure, (Smyrna, GA) and Sartomer Corp. (Exton, PA). As used herein, the term"mixtures of multifunctional acrylates"means mixtures of different acrylates of the same species, such as two different epoxy acrylates, or mixtures of different species of acrylates, such as epoxy acrylates and urethane acrylates.

Ethylenically Unsaturated Acid In addition to the bis-silane and the multifunctional acrylate, a quantity of an ethylenically unsaturated acid is added to the composition. By"ethylenically unsaturated acid" it is meant any acid which has vinyl unsaturation. It is believed that the ethylenically unsaturated acid substantially improves the oxygen barrier performance of the composition because the carboxylic group forms an amine salt with amino groups of the bis-silane, which contributes significantly to the coating's barrier properties. The ethylenically unsaturated acid is likely to be added in the amount of at least 5 to about 60 parts by weight of the composition, with about 30 to about 50 parts by weight being most preferred. The most preferred ethylenically unsaturated acids used in the present invention are dicarboxylic (i. e. have two carboxylic acid groups) and the most preferred is itaconic acid ; however, other acids such as fumaric, maleic, citraconic, methacrylic, cinnamic, vinyl sulfonic acid, mesaconic acid, and itaconic acid monomethylester may also be used. The term"ethylenically unsaturated acid"as used herein includes mixtures of one or more of the aforementioned acids.

Optional Aminofunctional Silanes The optional aminofunctional silanes are described generally by the formula : wherein a is 0-4, i. e., 0 < a < 4 ; R3 is independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, acryl, methacryl, alkylaryl, R4-SiRm (OR) 3 m, or an alkylene linking group having 2 to 12 carbon atoms connected to one or two nitrogen atoms, with the proviso that at least one R3 is a hydrogen atom and at most one R3 is an R4-SiRm (OR) 3_m group, where m is 0, 1 or 2, and R is independently a hydrogen or an alkyl group having from 1 to 6 carbon atoms ; R4 is independently selected from the group consisting of linear or branched alkylene groups having from 1 to 12 carbon atoms ; arylene groups having from 6 to 12 carbon atoms ; and linear or branched hydrocarbon groups having from 1 to 16 carbon atoms and at least one alcohol, alcohol ether, ester, amide, urea, thiourea or polyether group.

The most preferred optional aminofunctional silanes useful for the present invention are N- (2-aminoethyl)-3-aminopropyltrimethoxy silane, and aminopropyltriethoxysilane, and blends thereof.

For the purposes of the present invention, the above mentioned amine functional silane group has the general formula In the above formula, R3 is a monovalent radical independently selected from the group consisting of hydrogen ; acryl, methacryl, alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, propyl, isobutyl, hexyl, octyl, decyl, dodecyl and octadecyl ; substituted alkyl having 1 to 18 carbon atoms, such as 3-chloropropyl and 3, 3, 3-trifluoropropyl ; aryl having 6 to 16 carbon atoms, such as phenyl and naphthyl ; substituted aryl having 6 to 30 carbon atoms, such as chlorophenyl, chlorotolyl and dichloroxylyl ; arylalkyl having 7 to 9 carbon atoms, such as benzyl, phenethyl and 3-phenylpropyl ; and alkylaryl having 7 to 16 carbon atoms, such as tolyl, xylyl, ethylphenyl and propyltolyl. According to the invention, at least one R3 group is hydrogen. Further, at most one R3 is an R4-SiRm (OR) 3 m group, where R is an alkyl group having from 1 to 6 carbon atoms, m is 0, 1, or 2 and R4 is defined below. The remaining R3 groups on the aminosilane are preferably hydrogen or methyl.

R3 can also be an alkylene linking group which links two different nitrogen atoms together, thus forming a cyclic aminosilane. The alkylene linking group can also be an arylene group which is connected to the same nitrogen atom. The alkylene linking group will have at least 2 carbon atoms and as many as 12 carbon atoms.

R4 is an organic connecting group which provides a separation of at least one carbon atom between the nitrogen atoms or the nitrogen and silicon atoms. Thus, R4 can be an alkylene group having at least 1 carbon atom or an arylene group having at least 6 carbon atoms.

Preferably, R4 is selected from the group consisting of ethylene, propylene, butylene, isobutylene, trimethylene, tetramethylene, and hexamethylene.

In addition, R4 can contain polar groups such as, linear or branched hydrocarbon groups having from 1 to 16 carbon atoms and at least one alcohol, alcohol ether, ester, amide, urea, thiourea or polyether group. Specific examples of such groups include, those having the general formula-CH2CH (OH) (CH2) x-,-CH2CH (OH) (CH2) x-0- (CH2) y-, -CH2CH (CH3) C (=O)-O- (CH2) y-,-CH2CH2C (=O)-O- (CH2) y-,-CH2CH2C (=O)-N (R)- (CH2) y-,-C (=O)-N (R)- (CH2) y-,-C (=S)-N (R)- (CH2) y-, or where x and y are each integers from 1 to 12. The hydroxyl and ester groups are highly polar, and it is believed the polar nature of the groups improve barrier properties.

Examples of specific amine-containing groups include such structures as -CH2CH2CH2NH2,-CH2CH2CH2N (H) CH2CH2NH2, -CH2CH2CH2N (H) CH2CH2N (H) CH2CH2NH2,-CH2CH2CH2CH2NH2, -CH2CH2CH2CH2CH2NH2,-CH2CH2CH2N (H) Me,-CH2CH2CH2N (H) CH2CH2NMe2, -CH2CH2CH2N (H) Et,-CH2CH2CH2N (Et) H,-CH2CH (CH3) CH2N (H) CH2CH2NH2 and -CH2CH (CH3) CH2NH2, inter alia, wherein Me and Et denote methyl and ethyl, respectively.

A specific example of an amine containing cyclic group is piperazine.

As used herein the term."aminofunctional silane"can mean a single species of the formula described above, such as N- (2-aminoethyl)-3-aminopropyltrimethoxy silane, or it can mean mixtures or one or more species of aminofunctional silanes, such as N- (2-aminoethyl)-3- aminopropyltrimethoxy silane and aminopropyltriethoxysilane.

The above described aminofunctional silanes can be prepared by methods known to those skilled in the art, and which are amply described in the chemical literature.

Solvents The components of the present invention can optionally be reacted together in a solvent.

In general, water, alcohols and blends thereof will serve as suitable solvents because the multifunctional acrylate and the ethylenically unsaturated acid are soluble therein. Typically, the solvent is an alcohol. In addition, the selected solvent must wet the substrate. Preferably, the solvent will not extend the drying time of the coating beyond what is commercially acceptable. The amount of solvent can range from about 0% to about 99% and is preferably from about 5% to about 95 parts by weight of the total composition. Preferred solvents are methanol, ethanol, n-propanol, isopropanol, butanol, and 1-methoxy-2-propanol (available as "Dowanol PM"from the Dow Chemical Co., Midland, MI).

Critical Ratios During the reaction of bis-silanes with multifunctional acrylates, it is possible to utilize an excess of multifunctional acrylate over and above that required to react with the amino nitrogen atoms. In multifunctional acrylates, such as pentaerythritol tetraacrylate, the amine chains attached to the trimethoxysilyl groups may also have pendent acrylate groups which will undergo further polymerization under the influence of ionizing radiation. It is believed that, under appropriate experimental conditions, the acrylate groups of the multifunctional acrylate and the amino groups of the bis-silane and/or aminofunctional silanes undergo an addition reaction (Michael Addition) upon mixing of these two components. In addition, hydroxyl groups and solvents present may interact with alkoxy groups attached to the silicone atoms of the bis-silanes and/or aminofunctional silane and cause a thickening of the composition at certain concentrations of the components in the solvent.

For example, one may employ an"amine rich"system, in which the total number of amine functional sites in the composition due to the bis-silanes and/or aminofunctional silane can be up to about five (5) times greater than the total number of acrylate sites in the composition due to the multifunctional acrylate, i. e., the ratio of amine functionality to the acrylate functionality can be from about 5 : 1 to about 1 : 1, with a ratio of about 3 : 1 to about 1 : 1 being preferred, and with a ratio of 1. 1 : 1 being most preferred. In the case where the bis-silane is bis- (gamma-trimethoxysilylpropyl) amine) and the multifunctional acrylate is pentaerythritol tetraacrylate, the ratios in the amine rich system can be expressed in terms of molar ratios, with the preferred molar ratio of bis-silane to multifunctional acrylate being from about 6 : 1 to about 4 : 1, with a molar ratio of about 4 : 1 being most preferred.

Excellent results can also be achieved using an"acrylate rich"system, where the total number of reactive nitrogen sites in the composition from the bis-silanes is up to about ten (10) times less than the total number of reactive acrylate sites in the composition due to the multifunctional acrylate, i. e., the ratio of amine functionality to acrylate functionality can be from about 1 : 1 to about 1 : 10, with a range of about 1 : 1 to about 1 : 6 being preferred, and with a ratio of 1 : 5 being most preferred. In the case where the bis-silane is bis- (gamma-trimethoxysilylpropyl) amine) and multifunctional acrylate is pentaerythritol tetraacrylate, the ratios of the acrylate rich system can be expressed in terms of molar ratios, with the preferred molar ratio of aminosilane to multifunctional acrylate being from about 1 : 1 to about 1 : 3, with a molar ratio of about 1 : 1. 2 being most preferred.

Although the order of addition of the components is not critical, certain methods are preferable. For example, the bis-silanes and the acrylate component can be added together to form a Michael Adduct, before the addition of the ethylenically unsaturated acid. Also, the ethylenically unsaturated acid may be added at some point after the Michael Addition reaction begins, but before the bis-silanes and/or the acrylate are completely consumed."Quenching"the reaction by adding the ethylenically unsaturated acid can occur at any point in the reaction process, i. e., the acid may be added to the bis-silanes before any acrylate is added, or after some of the acrylate is added. Practically, the reaction may be quenched at a predetermined point by simply adding part of the acrylate to the bis-silanes, then adding the rest of the acrylate and the acid to this mixture. It is preferred that the quenching technique be used where the acid is first added to the bis-silanes or mixture of bis-silane/aminosilane prior to the addition of any acrylate.

Coating Thickness The coating can be applied in any desired amount, however, it is preferred that the coating be applied in a thickness ranging from 0. 05 um to 15 pm, the preferred coating thickness range being from about 0. 5 to about 7 pm. Coating thickness can be determined by Scanning Electron Microscopy or by the use of a profiler (Tencor P-1 Long Scan Profilometer, Tencor Instruments, Santa Clara, CA). The coating can be applied to the substrate by any conventional method, such as spray coating, roll coating, slot coating, meniscus coating, immersion coating, and direct, offset, and reverse gravure coating.

Substrates The coating can be disposed on a wide variety of substrates, including, but not limited to polyolefins, such as oriented polypropylene (OPP), cast polypropylene, polyethylene and polyethylene copolymers, polystyrene, polyesters, such as polyethylene terephthalate (PET), or polyethylene naphthalate (PEN), polyolefin copolymers, such as ethylene vinyl acetate, ethylene acrylic acid and ethylene vinyl alcohol (EVOH), polyvinylalcohol and copolymers thereof, polyamides such as nylon and meta-xylene adipamide (MXD6), polyimides, polyacrylonitrile, polyvinylchloride, polyvinylidene dichloride, and polyacrylates, ionomers, polysaccharides, such as regenerated cellulose, and silicone, such as rubbers or sealants, other natural or synthetic rubbers, glassine or clay coated paper, paper board or craft paper, and metallized polymer films and vapor deposited metal oxide coated polymer films, such as AlOX, SiOx, or TiOX.

The aforesaid substrates are likely to be in the form of a film or sheet, though this is not obligatory. The substrate may be a copolymer, a laminate, a coextrudate, a blend, a coating or a combination of any of the substrates listed above according to the compatibility of the materials with each other. In addition, the substrate may be in the form of a rigid container made from materials such as polyethylene, polypropylene, polystyrene, polyamides, PET, EVOH, or laminates containing such materials.

The aforesaid substrates may also be pretreated prior to coating by corona treatment, plasma treatment, acid treatments and flame treatments, all of which are known in the art.

In addition, the compositions of the present invention can be used for a wide variety of packaging containers, such as pouches, tubes, bottles, vials, bag-in-boxes, stand-up pouches, gable top cartons, thermo-formed trays, brick-packs, boxes, cigarette packs and the like. In addition, the compositions of the present invention may be used as a laminating adhesive.

Of course, the present invention is not limited to just packaging applications, and may be used in any application wherein gas, or aroma barrier properties are desired, such as tires, buoyancy aides, inflatable devices generally, etc.

Any of the foregoing substrates may have a primer or primers applied thereon. The primers are applied to the substrates by methods known in the art such as spray coating, roll coating, slot coating, meniscus coating, immersion coating, and indirect, offset, and reverse gravure coating. Suitable primers include, but are not limited to carbodiimide, polyethylenimine, and silanes, such as N- (2-aminoethyl)-3-aminopropyltrimethoxy silane and aminopropyltriethoxysilane.

Curing While the compositions of the present invention will form films at ambient conditions, optimum results are achieved by heating and/or free radical cures. Generally, the higher the temperature, the faster the coating will solidify. The upper limit to the heating is the temperature at which the substrate will undergo unacceptable distortion. Also, heating will accelerate the rate of hydrolysis of silicon/alkoxy groups and also the rate of condensation of the silicon bonded alkoxy groups with silicon bonded hydroxy groups to form silicon-oxygen- silicon groups. The composition may be dried at room temperature or in an oven at temperatures up to about 140°C, with temperatures of from about 60°C to about 120°C being preferred and temperatures of about 80°C to about 110°C being most preferred. Heating time is temperature dependent and the coating will reach tack free time in one to 10 seconds. The heating step serves to evaporate the solvent when used and accelerate the condensation reaction between Si-OH groups and SiOH/SiOH groups.

The compositions may be further cured by initiating a free radical reaction. The most preferred method of initiating the free radical reaction is through the use of electron beam radiation, although ultraviolet or free radical generators such as azo compounds and peroxides may also be used.

The compositions are preferably cured by a free radical generator, such as ultraviolet, electron beam, or gamma radiation or chemical free radical generators such as azo compounds and peroxides. Low energy electron beam irradiation is the preferred method of curing because it is cheaper than gamma sources like Cobalt M-60. Its advantage over ultraviolet radiation as a cure system lies in its ability to generate free radicals without photoinitiators. It also imparts higher yields of crosslink density and chemical grafting of the coating to the substrate. Electron beam accelerators of various types such as van de Graaf-type, resonance transformer-type, linear-type, dynamatron-type and high frequency-type can be used as a source of electron beam.

Electron beam having energy of from about 5 to about 2000 KeV, preferably from about 50 to about 300 KeV discharged therefrom may be irradiated in a dose of from about 0. 1 to about 30 Mrads (MR). Low electron beam voltages (less than 20 KeV) may be used if the substrate is treated in a vacuum. Commercially available sources of electron beam are Electro Certain@ CB-150 available from Energy Sciences, Inc. (Wilmington, MA).

The compositions may also be ultraviolet light cured if one or more photoinitiators is added prior to curing. There are no special restrictions on the photoinitiators as long as they can generate radicals by the absorption of optical energy. Ultraviolet light sensitive photoinitiators or blends of initiators used in the UV cure of the present composition include 2-hydroxy-2- methyl-l-phenyl-propan-l-one (Darocure 1173), sold by EM Chemicals, and 2, 2 Dimethoxy- 2-phenyl-acetol-phenone (Irgacure 651), sold by Ciba-Geigy Corporation, Hawthorne, New York. For purposes of this invention, it has been found that from about 0. 05 to about 5 weight percent based on the total solids in the composition, of the photoinitiators described herein will cause the composition to cure.

In addition to radical polymerization and grafting to crosslink the coating after it has been applied to the substrate, it is possible to further crosslink the composition utilizing acid catalyzed condensation reactions. In this reaction, a methoxylated active hydrogen compound, such as trimethylol phenol, or a mixture of formaldehyde with aldehydes, ketones, and other active hydrogen compounds react with amine salts, such as the itaconate salts of the amine silanes or derivatives to form alkylated amines.

Preferred Embodiment To prepare the preferred embodiment of the invention, the bis-silane component, preferably bis- (gamma-trimethoxysilylpropyl) amine) (2. 7 g) is dissolved in a solvent such as methanol. Itaconic acid (4. 2 g) is added to this solution. This mixture is allowed to equilibrate for one hour. The acrylate, preferably pentaerythritol tetraacrylate (PETA) (1. 1 g in 6g methanol), is added to the above solution and the mixture is allowed to equilibrate for 15 hours at ambient conditions. The coating solution is applied to corona treated 30 micron thick oriented polypropylene film from UCB Films (product # T217/30) and the coated film is allowed to dry under ambient conditions for 20 minutes. The dried coated film is then"cured" by an electron beam dose of 10 Megarads at 170 Kv.

Optional Additives Various optional additives can be added to the composition to improve various properties. These additives may be added as desired and in any amount as long as they do not reduce the performance of the barrier coatings as illustrated herein. Examples of additives include additional additives as earlier described, antiblock and slip aides such as stearamide, oleamide or polar additives, such as epoxides, polyols, glycidols or polyamines, such as polyethylenimine, and other silanes may be added. Specifically excluded from the scope of the present invention are colloidal silicas and silanes or other molecules having four alkoxy or other hydrolyzable groups disposed on a single silicone or other organometalic atom, such as tetra ethoxy silane, and the like. Wetting agents, such as a polyethoxylated alkyl phenyol may also be added.

Examples Experiments 1-5---UV cured 20 : 49 : 31 wt (Z6020 : PETA : ITA).

In experiments 1-5 the (Z-6020/A1170), acrylate ester, and itaconic acid were utilized in a weight ratio of 20 : 49 : 31 with a total solids content of 8 grams/20 grams of solution. The Dow Corking) Z6020 was N- (2-amino ethyl) gamma aminopropyl trimethoxysilane ("Z-6020") available from Dow Coming Corporation (Midland, MI.). The Silquest Al 170 ("Al 170") was bis- (g-trimethoxysilylpropyl) amine available from (Witco/Osi, Greenwich, CT). The solvent employed in all the experiments described below was methanol. The acrylate ester was obtained from Sartomer (Exton, PA), the itaconic acid from Aldrich Chemical Company (Milwaukee, WI), the wetting agent (Ebecryl 1360) from Radcure/UCB (Smyrna, GA) and the photoinitiator (Darocur 1173) from CIBA Additives (Tarrytown, NY). The coating solutions were all applied to corona treated 30 pm thick oriented polypropylene film from UCB Films (product T217/30) utilizing a #10 Mayer rod. The coated film was allowed to dry under ambient conditions for 20 minutes. The dried coated film was then"cured"by a UV machine.

The oxygen permeability values for each film were measured and recorded in units of cc/square meter per 24 hours,"dry"values being measured at 0% relative humidity and"wet" values at 90% relative humidity utilizing MOCON Oxtran 2/20 Series. The MOCON@N instruments were obtained from Modern Controls Corporation. For comparison, the polypropylene base film had a permeability of about 1200 cc/square meter/24 hours. The coating layer thickness was measured by means of Scanning Electron Microscopy (SEM).

Experiment 1 A solution of 1. 6g of Z6020 and 6g methanol was prepared and 2. 5g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 3. 9g PETA in 6g methanol and stirred overnight. The photoinitiator (Daracur 1173-0. 32g) and wetting agent (Ebecryl 1360-0. 004g) were added 5 minutes prior to coating. After coating, drying and curing, the permeability was 9. 3cc dry and 133cc wet and the thickness of the coating layer was determined to be 5. 18 Mm.

Experiment 2 A solution of 1. 2g of Z6020, 0. 4g of A1170 and 6g methanol was prepared and 2. 5g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 3. 9g PETA in 6g methanol and stirred overnight. The photoinitiator (Daracur 1173-0. 32g) and wetting agent (Ebecryl 1360-0. 004g) were added 5 minutes prior to coating. After coating, drying and curing, the permeability was 9. 4cc dry and 94cc wet and the thickness of the coating layer was determined to be 6 um.

Experiment 3 A solution of 0. 8g of Z6020, 0. 8g of Al 170 and 6g methanol was prepared and 2. 5g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 3. 9g PETA in 6g methanol and stirred overnight. The photoinitiator (Daracur 1173-0. 32g) and wetting agent (Ebecryl 1360-0. 004g) were added 5 minutes prior to coating. After coating, drying and curing, the permeability was 23cc dry and 185cc wet and the thickness of the coating layer was determined to be 3. 03 um.

Experiment 4 A solution of 0. 4g of Z6020, 1. 2g of A1170 and 6g methanol was prepared'and 2. 5g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 3. 9g PETA in 6g methanol and stirred overnight. The photoinitiator (DaracurQ) 1173-0. 32g) and wetting agent (Ebecryl 1360-0. 004g) were added 5 minutes prior to coating. After coating, drying and curing, the permeability was 14cc dry and 64cc wet and the thickness of the coating layer was determined to be 5 pm.

Experiment 5 A solution of 1. 6g of Al 170 and 6g methanol was prepared and 2. 5g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 3. 9g PETA in 6g methanol and stirred overnight. The photoinitiator (Daracur 1173-0. 32g) and wetting agent (Ebecryl 1360-0. 004g) were added 5 minutes prior to coating. After coating, drying and curing, the permeability was 10. 8cc dry and 85cc wet and the thickness of the coating layer was determined to be 2. 55 pm.

The data for experiments 1-5 is shown in Table 1 below. The dry and wet permeability values have been normalized to a coating thickness of 3 um.

Table 1 Expt. Material OTR¹ OTR Coating OTR OTR # A1170:Z602 90% RH 0% RH Thickness predicted² predicted² 0 Ratio cc/m²/day cc/m²/day µm 3 µm coating 3 µm coating 90% RH 0%RH cc/m²/day cc/m²/day 90% RH 0% RH cclm2lday cclm2lday 1 0 : 100 133 9. 3 5. 18 213 16 2 25 : 75 94 9. 4 6 175 18. 7 3 50 : 50 185 23 3. 03 187 23. 2 4 75 : 25 64 14 5 103 23. 2 5 100 : 0 85 10. 8 2. 55 73 9. 2 In Table 1, the following abbreviations were used, where : 1 : OTR is oxygen transmission rate or oxygen gas permeability 2 : OTR predicted was calculated by the use of the Generic Composite Permeability Eqt : Tt/Pt = Ts/Ps + Tc/Pc where T refers to the thickness, in microns, and P to the permeability coefficient of the composite (Tt, Pt), substrate (Ts, Ps), & adhesive (Tc, Pc).

The substrate OPP was measured to be 30 microns thick and have an OTR of 1238cc/m2/day as measured at 90% RH.

3 : same as 2 except that the permeability was measured to be 1191 cc/m2/day at 0% RH The data in Table 1 clearly shows that increasing amounts of the bis-silane A-1170 significantly improves the oxygen barrier at 90% relative humidity over the formulation absent the bis-silane.

Experiments 6-10---EB cured 34 : 14 : 52 wt (Z6020 : PETA : ITA).

In experiments 6-10 the (Z-6020/A1170), acrylate ester, and itaconic acid were utilized in a weight ratio of 34 : 14 : 52 with a total solids content of 8 grams/20 grams of solution. The solvent employed in all the experiments described below was methanol, available commercially from Fisher. The Z-6020 was obtained from Dow Coming Corporation (Midland, MI), the Silquest Al 170 from Witco/OSi (Greenwich, CT), the acrylate ester from Sartomer (Exton, PA) and the itaconic acid from Aldrich Chemical Company (Milwaukee, WI). The coating solutions were all applied to corona treated 30 pm thick oriented polypropylene film from UCB Films (product T217/30) utilizing a &num 18 Mayer rod. The coated film was allowed to dry under ambient conditions for 3hours. The dried coated film was then"cured"by an EB machine at lOMegarads and 170Kv.

Experiment 6 A solution of 2. 7g of Z6020 and 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 1. 7cc dry and 101. 4cc wet and the thickness of the coating layer was determined to be 5. 2 pm.

Experiment 7 A solution of 2. 03g of Z6020, 0. 68g of A1170 and 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 16. See dry and 43. 6cc wet and the thickness of the coating layer was determined to be 5. 1 prn.

Experiment 8 A solution of 1. 35g of Z6020, 1. 35g of Al 170 and 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 1. 6cc dry and 32. 2cc wet and the thickness of the coating layer was determined to be 4. 6 um.

Experiment 9 A solution of 0. 68g of Z6020, 2. 03g of 1170 and 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1g PETA in 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 9. 4cc dry and 11 cc wet and the thickness of the coating layer was determined to be 4. 3 jjm.

Experiment 10 A solution of 2. 7g of Al 170 and 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 3cc dry and 12. 3cc wet and the thickness of the coating layer was determined to be 4 jum.

The data for experiments 6-10 is shown in Table 2 below. The dry and wet permeability values have been normalized to a coating thickness of 3 pm.

Table 2 Expt. Material OTR1 OTR Coating OTR OTR # A1170 : Z60 90% RH 0% RH Thickness predicted2 predicted3 20 Ratio ccm2/day cc/m2/day µm 3 µm coating 3 µm coating 90% RH 0% RH cc/m2/dav cc/m2/dav 6 0 : 100 101. 4 1. 7 5. 2 165. 8 2. 9 7 25 : 75 43. 6 16. 8 5. 1 72. 3 28. 3 8 50 : 50 32. 2 1. 6 4. 6 48. 7 2. 5 9 75 : 25 11 9. 4 4. 3 15. 7 13. 4 10 100 : 0 12. 3 3 4 16. 3 4 The data in Table 2 clearly shows that increasing amounts of the bis-silane A-1170 significantly improves the oxygen barrier at 90% relative humidity over the formulation absent the bis-silane.

Experiments 11-13 =--EB cured 34 : 14 : 52 wt (Z6020 : PETA : ITA) with bis-TMSEDA (Gelest) In experiments 11-13-the (Z-6020/bis-TMSEDA), acrylate ester, and itaconic acid were utilized in a weight ratio of 34 : 14 : 52 with a total solids content of 8 grams/20 grams of solution. The solvent employed in all the experiments described below was methanol, available commercially from Fisher. The Z-6020 was obtained from Dow Corning Corporation (Midland, MI), the bis-TMSEDA (bis- [ (3-trimethoxysilyl) propyl] ethylenediamine, 62% solution in methanol) from Gelest (Tullytown, PA), the acrylate ester from Sartomer (Exton, PA) and the itaconic acid from Aldrich Chemical Company (Milwaukee, WI). The coating solutions were all applied to corona treated 30 pm thick oriented polypropylene film from UCB Films (product T217/30) utilizing a #18 Mayer rod. The coated film was allowed to dry under ambient conditions for 3 hours. The dried coated film was then"cured"by an EB machine at l OMegarads and 170Kv.

Experiment 11 A solution of 2. 03g of Z6020, 1. 09g of bis-TMSEDA and 5. 8g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 5. 8g methanol and stirred overnight. After coating, drying and curing, the permeability was 3. Ice dry and 49. 4cc wet and the thickness of the coating layer was determined to be 6. 6 pin.

Experiment 12 A solution of 1. 35g of Z6020, 2. 18g of bis-TMSEDA and 5. 6g methanol was prepared and 4. 2g of itaconic acid was added with stirring. After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 5. 6g methanol and stirred overnight. After coating, drying and curing, the permeability was 0. 5cc dry and 53. 8cc wet and the thickness of the coating layer was determined to be 6 um.

Experiment 13 A solution of 0. 68g of Z6020, 3. 27g of bis-TMSEDA and 5. 4g methanol was prepared and 4. 2g of itaconic acid was added with stirring., After a minimum of 30 minutes at ambient temperature, this mixture was added to a solution of 1. 1 g PETA in 5. 4g methanol and stirred overnight. After coating, drying and curing, the permeability was 0. 5cc dry and 9. 2cc wet and the thickness of the coating layer was determined to be 6. 5 µm .

The barrier data for experiments 11-13 is shown in Table 3 below.

Table 3 Expt. Material OTR1 OTR Coating OTR OTR 3 # bis- 90% RH 0% RH Thicknes predicted² predicted³ TMSEDA cc/m²/day cc/m²/day s µm 3µm coating 3 µm coating @Z6020 Ratio 90% RH 0% RH cc/m²/day 00/m²/day 6 0:100 101.4 1.7 5.2 165.8 2.95 11 25:75 49.4 3.1 6.6 103.7 6.82 12 50 : 50 53. 7 0. 5 6 102. 9 1 13 75: 25 9. 2 0. 5 6. 5 19. 8 1 1. 1 The data in Table 3 clearly shows that increasing amounts of the bis-silane A-1170 significantly improves the oxygen barrier at 90% relative humidity over the formulation absent the bis-silane.

The foregoing specification describes only the preferred embodiment and the alternate embodiments of the invention. Other embodiments may be articulated as well. It is expected that others will perceive differences which while differing from the foregoing, do not depart from the spirit and scope of the invention herein described and claimed.