WO1999058328A2

WO1999058328A2 - Multilayer polymer compositions displaying imroved recyclability

Info

Publication number: WO1999058328A2
Application number: PCT/US1999/010009
Authority: WO
Inventors: Stephen Weinhold; Karen Anne Harding; Timothy Edward Long; Martin Emerson Rogers; David Richard Fagerburg; Billy Pat Evans
Original assignee: Eastman Chemical Company
Priority date: 1998-05-11
Filing date: 1999-05-07
Publication date: 1999-11-18
Also published as: WO1999058328A3; AR016475A1; AU4071799A

Abstract

The present invention relates to a multilayer structure comprising at least two layers of different composition wherein said layers are rendered separable by the incorporation or interdisposition of at least one recycle release aid. Specifically, the present invention relates to a multilayer material comprising: a structural layer comprising at least one polymer; a performance layer which displays at least one physical property which is superior to said structural layer's physical properties; and at least one recycle release material which promotes interlayer release under recycling conditions, but maintains or improves interlayer adhesion between said structural and performance layers during use conditions.

Description

Multilayer Polymer Compositions Displaying Improved Recvclability

Cross References to Related Applications

This application claims the benefit of United States Provisional Applications Serial Nos. 60/084,916 filed May 11 , 1998, 60/089,310, filed June 15, 1998 and 60/096,677, filed August 15, 1998.

Background of the Invention

Thermoplastic polymers are widely used to manufacture packaging for foods, beverages, and other products. The packaging may be in the form of blow-molded containers, thermoformed sheet, film, injection molded containers, and in other forms well known to those skilled in the art. One essential function of such packaging is to provide a barrier to the migration of gasses, vapors, and other molecules into or out of the package. Other multilayer needs include protection from degradation by visible and/or ultraviolet light, improved heat distortion and sealing characteristics, improved flexibility in creating colored packaging structures and the like. Frequently multilayer structures are made from polymers having significantly different compositions. Many multilayer compositions display poor adhesive qualities between the layers, which result in a poor packaging material. Many of the layers which are under consideration as candidates for multilayer packaging are either incompatible with the polyesters which are currently used, or sufficiently different that they could not be introduced into conventional polymer recycling streams. Accordingly, there remains a significant need in the art for intermediate packaging layers which display good adhesion to the primary layers during use, but can be readily separated to allow recycling of the packaging material. Description of the Invention

Surprisingly, the recycle release aids of the present invention also improve the interlayer adhesion of structural and performance layers displaying poor interlayer adhesion. Thus, the multilayer structures of the present invention display both good interlayer adhesion during use and ready separation via conventional recycling methods such as washing with water and other conventional washing compounds.

Specifically, an embodiment of the present invention relates to multilayer structures comprising at least two structural layers having an intermediate performance layer comprising at least one recycle release aid. It should be appreciated that the layers of the present invention need not be formed at the same time. For example, a conventional container and label could be independently formed, either the exterior surface of the container or the interior surface of the label coated with at least one recycle release aid and then the label and container could be adhered together. Alternatively, the multilayer structure could be formed in a single process such as coextrusion or coinjection molding.

Another embodiment of the present invention is a multilayer structure comprising at least one structural layer and at least one performance layer wherein at least one of said performance layers comprises a barrier polymer and at least one recycle release aid incorporated therein. This embodiment is particularly desirable when the first and second polymeric layer display poor interlayer adhesion.

Yet another embodiment of the present invention is a multilayer structure which comprises a structural layer which may or may not have improved physical properties, an intermediate layer comprising at least one recycle release aid, and a performance layer which displays good interlayer adhesion with the structural layer. This embodiment displays improved recyclability. Yet another embodiment of the present invention relates to a multilayer structure comprising a first structural layer and a second performance layer which is coated onto the structural layer. In this embodiment the recycle release aid may be incorporated into the performance layer or interposed between the performance and structural layers by conventional means such as coextrusion with the structural layer or an intermediate coating step.

Performance Layer

At least one layer in the multilayer structures of the present invention provides the resulting container with improved physical properties. Such properties include, but are not limited to barrier to migration (gas, vapor, and/or other small molecules), barrier to harmful light (ultraviolet light) and mechanical properties such as heat resistance, stress crack resistance, impact strength, sealability, processability and the like. In one embodiment the performance layer displays improved C0₂ and/or 0₂ barrier compared to unmodified PET homopolymer. In certain embodiments all of the layers of the multilayer structure are modified to display barrier properties which are improved compared to unmodified, conventional PET. For the purposes of this invention, improved physical properties means an improvement of at least about 5 %, and preferably at least about 10% in at least one property as compared to unmodified PET, or the structural layer which is selected. The number and thickness of the performance layers which are included in the desired multilayer structure may vary. Generally, the multilayer articles of the present invention will have at least one performance layer, and one structural layer, preferably between 1 and 5 performance layers and more preferably between 1 and 3 performance layers. The thickness of the performance layer is determined primarily by the method of introducing said performance layer and the performance improvement required by the article being formed. Generally the performance layer(s) can be up to 200 microns, and preferably up to about 100 microns in the final article. It should be appreciated that performance layers applied as coatings will be a the very low end of the range, while coinjected layers, labels and sleeves will vary between about 10 microns and about 100 microns. Preferably the performance layer will be incorporated at a thickness which does not detract from the physical appearance of the final article. These thicknesses refer to the major portion of the package. In some instances, for example the undrawn finish and neck region of a blow molded container, the performance layer in small regions of the package may be substantially thicker.

Suitable materials for the performance layer(s) of the present invention include polyamides, saponified ethylene-vinyl acetate copolymer (EVOH), polyalcohol ethers, wholly aromatic polyesters, resorcinol diacetic acid-based copolyesters, polyalcohol amines, isophthalate containing polyesters, PEN and its copolymers and mixtures thereof. Performance materials may be used neat or may be modifed to further improve their physical properties, such as with the addition of nanoparticles (to improve barrier), such as those available from Nanocor, Southern Clay Products, Rheox and others. Other known additives may also be added to improve various physical properties. Suitable polyamides include partially aromatic polyamides, aliphatic polyamides, wholly aromatic polyamides and mixtures thereof. By "partially aromatic polyamide" it is meant that the amide linkage of the partially aromatic polyamide contains at least one aromatic ring and a nonaromatic species.

Suitable polyamides have a film forming molecular weight and preferably an I.V. of greater than about 0.4, Wholly aromatic polyamides comprise in the molecule chain at least 70 mole % of structural units derived from m-xylylene diamine or a xylylene diamine mixture comprising m-xylylene diamine and up to 30% of p-xylylene diamine and an α,ω -aliphatic dicarboxylic acid having 6 to 10 carbon atoms, which are further discribed in Japanese Patent Publications No. 1156/75, No. 5751/75, No. 5735/75 and No. 10196/75 and Japanese Patent Application Laid-Open Specification No. 29697/75. Polyamides formed from isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, meta- or para-xylylene diamine, 1 ,3- or 1 ,4-cyclohexane(bis)methylamine, aliphatic diacids with 6 to 12 carbon atoms, aliphatic amino acids or lactams with 6 to 12 carbon atoms, aliphatic diamines with 4 to 12 carbon atoms, and other generally known polyamide forming diacids and diamines can be used. The low molecular weight polyamides may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, pyromellitic dianhydride, or other polyamide forming polyacids and polyamines known in the art.

Preferred partially aromatic polyamides include: poly( -xylylene adipamide), poly(hexamethylene isophthalamide), poly(hexamethylene adipamide-co-isophthalamide), poly(hexamethylene adipamide-co- terephthalamide), and poly(hexamethylene isophthalamide-co- terephthalamide). The most preferred partially aromatic polyamide is poly(/77-xylylene adipamide). Preferred aliphatic polyamides include poly(hexamethylene adipamide) and poly(caprolactam). The most preferred aliphatic polyamide is poly(hexamethylene adipamide). Partially aromatic polyamides, are preferred over the aliphatic polyamides where good thermal properties are crucial. Preferred aliphatic polyamides include polycapramide (nylon 6), poly-aminoheptanoic acid (nylon 7), poly-aminonanoic acid (nylon 9), polyundecane-amide (nylon 11), polyaurylactam (nylon 12), polyethylene- adipamide (nylon 2,6), polytetramethylene-adipamide (nylon 4,6), polyhexamethylene-adipamide (nylon 6,6), polyhexamethylene-sebacamide (nylon 6,10), polyhexamethylene-dodecamide (nylon 6,12), polyoctamethylene-adipamide (nylon 8,6), polydecamethylene-adipamide (nylon 10,6), polydodecamethylene-adipamide (nylon 12,6) and polydodecamethylene-sebacamide (nylon 12,8).

The saponified ethylene-vinyl acetate copolymer (hereinafter referred to as "EVOH") is a polymer prepared by saponifying an ethylene-vinyl acetate copolymer having an ethylene content of 15 to 60 mole % up to a degree of saponification of 90 to 100%. The EVOH copolymer should have a molecular weight sufficient for film formation, and a viscosity of generally at least 0.01 dl/g, especially at least 0.05 dl/g, when measured at 30°C in a phenol/water solvent (85:15).

Suitable polyalcohol ethers include the phenoxy resin derived from reaction of hydroquinone and epichlorohydrin as described in US 4,267,301 and US 4,383,101. These materials can also contain resorcinol units and may in fact be all resorcinol units as opposed to hydroquininone units for the aromatic residue.

Suitable wholly aromatic polyesters (frequently called LCPs) are formed from repeat units comprising terephthalic acid, isophthalic acid, dimethyl-2,6-naphthalenedicarboxylate, 2,6-naphthalenedicarboxylic acid, hydroquinone, resourcinol, biphenol, bisphenol A, hydroxybenzoic acid, hydroxynaphthoic acid and the like. Suitable diacetic resourcinol copolymers are described in US 4,440,922 and US 4,552,948 and consist of copolyesters of terephthalic acid, ethylene glycol and a modifying diacid from 5 to 100 mol% in the composition replacing terephthalate units. The modifying diacid is either m- phenylenoxydiacetic acid or p-phenylenoxydiacetic. Either one of these diacids can be employed either by themselves or as mixtures in preparation of the copolyesters.

Suitable polyalcohol amines include those derived from reaction of either resorcinol bisgylcidyl ether with an alkanol amine, such as ethanolamine, or hydroquinone bisglycidyl ether with an alkanol amine.

Mixtures of these bisglycidyl ethers can obviously also be used in preparation of a copolymer.

Suitable isophthalate containing polyesters, include polyesters comprising repeat units derived from at least one carboxylic acid comprising isophthalic acid (preferably at least 10 mole %) and at least one glycol comprising ethylene glycol.

Suitable PEN and PEN copolymers include polyesters comprising repeat units derived from at least one carboxylic acid comprising naphthalene dicarboxylic acid (preferably at least 10 mole %) and at least one glycol comprising ethylene glycol.

Structural Layer

The structural layer comprises one or more polymer which provides the mechanical and physical properties required of the package. The number and thickness of the structural layers which are included in the desired multilayer structure may vary. Generally, the multilayer articles of the present invention will have at least one performance layer, and one structural layer. The number and thickness of the structural layer is determined primarily by the method of forming the article, and the base performance requirements of the article being formed. For example, a film may require fewer and thinner structural layers than a blow molded container. Generally the structural layer(s) can be up to 1000 microns, and preferably up to about 500 microns. These thicknesses refer to the major portion of the package. In some instances, for example the undrawn finish and neck region of a blow molded container, the structural layer in small regions of the package may be substantially thicker.

Suitable polymers include polyester homopolymer or copolymer that are suitable for use in packaging, and particularly food packaging. Suitable polyesters are generally known in the art and may be formed from aromatic dicarboxylic acids, esters of dicarboxylic acids, anhydrides of dicarboxylic esters, glycols, and mixtures thereof. As used herein, the term "repeat units from dicarboxylic acid" repeat units from the esters and anhydrides of said dicarboxylic acids. Suitable partially aromatic polyesters are formed from repeat units comprising terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl-2,6-naphthalenedicarboxylate, 2,6- naphthalenedicarboxylic acid, 1,2-, 1,3- and 1 ,4-phenylene dioxydoacetic acid, ethylene glycol, diethylene glycol, 1,4-cyclohexane-dimethanol, 1 ,4- butanediol, and mixtures thereof. Preferred the structural polyesters comprise repeat units comprising terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl-2,6- naphthalenedicarboxylate and mixtures thereof. More preferably the polyesters used in the structural layer comprise at least about 50 mol% and most preferably at least about 70 mol% terephthalic acid in the dicarboxylic acid component. The dicarboxylic acid component of the polyester may optionally be modified with one or more different dicarboxylic acids (up to about 30 mol% and more preferably up to about 20 mol%). Such additional dicarboxylic acids include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaiiphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Examples of dicarboxylic acids to be included with terephthalic acid are: phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'- dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, mixtures thereof and the like.

Preferably the glycol component comprises ethylene glycol. The glycol component may optionally be modified with one or more different diols other than ethylene glycol (preferably up to about 20 mole%). Such additional diols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Examples of such diols include: diethylene glycol, triethylene glycol, 1 ,4- cyclohexanedimethanol, propane-1,3-diol, butane-1 ,4-diol, pentane-1 ,5-diol, hexane-1,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol-(1 ,4), 2,2,4- trimethylpentane-diol-(1 ,3), 2-ethylhexanediol-(1 ,3), 2,2-diethylpropane-diol- (1,3), hexanediol-(1,3), 1 ,4-di-(hydroxyethoxy)-benzene, 2,2-bis-(4- hydroxycyclohexyl)-propane, 2,4-dihydroxy-1 ,1 ,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, 2,2-bis-(4-hydroxypropoxyphenyl)- propane, hydroxyethyl resourcinol, mixtures thereof and the like. Polyesters may be prepared from two or more of the above diols. The resin may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol, and other polyester forming polyacids or polyols generally known in the art.

Polyesters can be made by conventional processes all of which are well known in the art, and need not be described here.

Recycle Release Aid

The recycling release aid of the present invention is an additive which improves the separability under recycling conditions of performance and structural layers. Surprisingly, the recycling release aids of the present invention improve the interlayer adhesion between structural and performance layers which display poor interlayer adhesion. The recycle release aid may be incorporated into the performance layer, interdisposed between the performance and structural layers or both. Surprisingly, the recycling release aid provides both good interlayer adhesion during use of the multilayer article and easy separation of the performance and structural layers during recycling. Preferably when the recycle release aid is incorporated into the performance layer it is incorporated in amounts sufficient to provide the desired level of release under recycling conditions but which are insufficient to degrade other properties of the performance layer, such as, but not limited to clarity. Thus, suitable amounts of recycle release aid will vary depending upon the composition of the performance layer. Generally, the amount of recycle release aid to be incorporated into the performance layer may be up to about 30 weight %, preferably up to about 25 weight %, and more preferably from about 1 to about 20 weight %. In certain embodiments of the present invention it has been found particularly advantageous to interdispose the recycle release aid between performance and structural layers which display good interlayer adhesion. When the recycle release aid is interdisposed between the layers it is as a thin tie layer. Suitable thicknesses include those up to about 50 microns, and preferably between about 2.5 to about 50 microns.

Suitable materials for forming the recycle release aids of the present invention include water soluble polymers, water dispersible polymers, and polymers which are either hydrophyllic, hydrolytically unstable or labile under recycling conditions. Preferably said recycle release aids are formed from water soluble polymers, water dispersible polymers and mixtures thereof.

Water soluble polymers are polymers which dissolve readily in water, such as polyacrylic acid, methacrylic acid and the like.

Water dispersible polymers form electrostatically-stabilized colloids when mixed with water. The colloid particle size varies with the polymer composition but has been shown by light diffraction studies and transmission electron microscopy (on fresh films) to be mostly 200-800 A in diameter. The aqueous colloid dispersions exhibit a minimum precipitation of solid material with time, in the temperature range of 0.1-99.9°C because the relationship between the particle densities and viscosities (very similar to those of water when concentrations are less than 30 weight percent) are such that thermal energy expressed as Brownian motion is sufficient to keep the particles suspended in water.

The water-dispersible polymers have an inherent viscosity of at least about 0.1 dLJg, preferably about 0.28-about 0.38 dUg, when determined at 25°C using 0.25 g polymer per 100 ml of a solvent consisting of 60 parts by weight phenol and 40 parts by weight tetrachloro-ethane. Suitable water- dispersible polymers include sulfonate-containing, water-dispersible, linear polymers, starch, thermoplastic starch, carboxymethyl cellulose and mixtures thereof.

Preferably the water dissipatable polymers include sulfonate- containing, water-dispersible, linear polymers comprising polyesters, including polyester-amides, consisting of repeating, alternating residues of (1) one or more dicarboxylic acids and (2) one or more diols or a combination of one or more diols and one or more diamines where, in the preceding definition, the mole percentages are based on 100 mole percent dicarboxylic acid residues and 100 mole percent diol or diol and diamine residues. Alternatively, the polymers may include residues of monomers having mixed functionality such as hydroxycarboxylic acids, aminocarboxylic acids and/or aminoalkanols.

Generally the water-dissipatable polyesters and polyesteramides derived from monomer components which include dicarboxylic acid, hydroxycarboxylic acid, aminocarboxylic acid, aminoalcohol, glycol, diamine or combinations of such monomer components wherein at least a part of the total of all such monomer components is poly(ethylene glycol), and at least a part of said total is one or more of said monomer components substituted with one or more sulfonate metal salt groups.

The residues of dicarboxylic acid component (1) may be derived from one or more dicarboxylic acids or their ester-forming derivatives such as dialkyl esters, bis(hydroxyalkyl) esters, acid chlorides or, in some cases, anhydrides. The sulfonate group may be an alkali metal sulfonic salt such as lithium, potassium or, preferably, sodium sulfonate groups, or an ammonium or substituted ammonium sulfonate.

A preferred group of water-dispersible polymers have an inherent viscosity of about 0.28 to 0.38 dL/g and are comprised of:

(i) diacid monomer residues comprising about 60 to about 84 mole percent isophthalic acid monomer residues and about 16 to about 30 mole percent 5-sodio-sulfoisophthalic acid monomer residues; and (ii) diol monomer residues comprising about 45 to about 80 mole percent diethylene glycol monomer residues and about 20 to about 55 mole percent ethylene glycol, 1 ,4-cyclohexanedimethanol monomer residues or mixtures thereof.

Specific embodiments of these water-dispersible polymers are available from Eastman Chemical Company, and include EASTMAN AQ 48 Ultra Polymer, EASTMAN AQ 29S Polymer, EASTMAN 38S Polymer and EASTMAN 55S Polymer. These polyesters have been shown to disperse in water due to the presence of 5-sodiosulfoisophthalic acid residues. Similar materials are also available from Rhone Poulenc, Toyoba and Sun Kyong. In the preferred form of the present invention, the polyester contains repeating units of a poly(ethylene glycol) of the formula H-(OCH₂-CH₂)n-OH wherein n is an integer of 2 to 500. The value of n is preferably from between about 2 to about 20.

Examples of suitable poly(ethylene glycols) include relatively high molecular weight polyethylene glycols, some of which are available commercially under the designation CARBOWAX, a product of Union Carbide. Diethylene glycol is also especially suitable.

Other useful glycols for preparing copolyesters include aliphatic, alicyclic and aralkyl glycols. Examples of these glycols include ethylene glycol; propylene glycol; 1 ,3-propanediol; 2,4-dimethyl-2-ethyIhexane-1 ,3- diol; 2,2-dimethyl-1 ,3-propanediol; 2-ethyl-2-butyl-1 ,3-propanediol; 2-ethyl-2- isobutyl-1 ,3-propanediol; 1,3-butanediol, 1 ,4-butanediol, 1,5-pentanediol, 1,6- hexanediol, 2,2,4-trimethyl-l ,6-hexanediol; thiodiethanol. 1 ,2- cyclohexanedimethanol, 1 ,3-cyclohexandimethanol; 1 ,4- cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and p- xylylenediol.

The dicarboxylic acid component of the polyesters are preferably selected from aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, or mixtures of two or more of these acids. Examples of such dicarboxylic acids, include succinic; glutaric; adipic; azelaic; sebacic; 1 ,4-cyclohexanedicarboxylic; phthalic; terephthalic and isophthalic acid. Terephthalic acid and isophthalic acid are preferred as the carboxylic acid component of the polyester.

It should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term "dicarboxylic acid."

The difunctional sulfomonomer component of the polyester may advantageously be a dicarboxylic acid or an ester thereof containing a metal sulfonate group, a glycol containing a metal sulfonate group or a hydroxy acid containing a metal sulfonate group. The metal ion of the sulfonate salt may be Na+, Li+, K+ and the like. When a monovalent alkali metal ion is used, the resulting polyesters are less readily dissipated by cold water and more readily dissipated by hot water. When a divalent or a trivalent metal ion is used the resulting polyesters are not ordinarily easily dissipated by cold water but are more readily dissipated in hot water. It is possible to prepare the polyester using, for example, a sodium sulfonate salt and latex and by ion- exchange replace this ion with a different ion, and thus alter the characteristics of the polymer. The difunctional monomer component may also be referred to the difunctional sulfomonomer and is further described herein below.

Advantageous difunctional sulfomonomer components are those wherein the sulfonate salt group is attached to an aromatic acid nucleus such as benzene, naphthalene, diphenyl, oxydiphenyl, sulfonyldiphenyl or methylenediphenyl nucleus. Preferred results are obtained through the use of sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and their esters.

Particularly superior results are achieved when the difunctional sulfomonomer component is 5-sodiosulfoisophthalic acid or its esters, and the glycol is a mixture of ethylene glycol or 1,4-cyclohexanedimethanol with diethylene glycol.

A particularly preferred water dissipatable polymer is composed of 80 mole parts of isophthalic acid, 10 mole parts of adipic acid, 10 mole parts of 5-sodiosulfoisophthalate, 20 mole parts of ethylene glycol and 80 mole parts diethylene glycol. Water soluble polymers include polyvinyl alcohol, polyvinylpyrollidone, polyacrylic acid, methacrylic acid and the like.

Other Additives

Any of the above described layers, in any combination, may contain additional additives or components which do not detract from the purpose of the present invention. Suitable additives include, but are not limited to nucleating agents, branching agents, colorants, pigments, fillers, antioxidants, ultraviolet light and heat stabilizers, impact modifiers, reheat improving aids, crystallization aids, acetaldehyde reducing additives, oxygen scavaging compounds, barrier improving additives such as treated platelet particles such as those disclosed in US 97/24221 , US 97/24104, US 97/24103, US 99/04510, the disclosures of which are incorporated herein by reference, and the like.

Labels

The performance layer of the present invention may comprise a layer of the container, a label applied to the container or both. Barrier labels may be comprised of any of the barrier materials described above, conventional label materials which have been modified with barrier enhancing additives such as barrier enhancing platelet particles, inorganic materials and mixtures thereof. Suitable inorganic materials include metal foil such as aluminum, a metal oxide coating such as Al₂0₃ , silicate based coatings and mixtures thereof. The multilayer label may be produced by laminating the structural layer with metal foil. An inorganic material such as Al₂0₃ and Si0₂ may be deposited as a layer onto a polymeric substrates by methods well known in the art. The barrier labels of the present invention may be applied via conventional means, which are also known in the art.

Suitable methods include, but are not limited to standard labeling machines where the label adhesive is activated by heat, such as a heating element including a heat gun, hot roller or the like. Application in such machines can also be made using a pressure sensitive form of adhesive while still maintaining the desirable property of release from the bottle during the recycle process.

Another method of label application includes pre-forming the label in any number of ways common in the art and inserting the pre-formed label into the mold used for blowing the bottle from the heated preform or parson. This would be done prior to final closure of the mold before the blowing operation is performed on the preform or parison. Thus, when the bottle is blown into its final shape in the mold, the bottle wall is automatically brought into intimate contact with the adhesive of the label while still in a hot enough condition to cause the label to form a good adhesive bond. The label does not have to be in a perfectly cylindrical shape to insure intimate contact and improved recyclability of the present invention. The label may contain contours and the like which may or may not mirror the contours of the preform, parison or the final container. All that is necessary is that the label conforms adequately to the inside of the mold into which the bottle is to be blown such that the label on the final bottle has an acceptable appearance. Those skilled in the art will readily appreciate the variety of mechanical sequences useful for accomplishing the essential elements of this method of label application to the final container.

In the above embodiments the recycle release aid may be applied to either or both the inside surface of the label and the exterior surface of the container via conventional methods such as coating, coextruding and the like. The adhesion promoting material may also be incorporated into the label material.

Alternatively the container and a sleeve of extrudable, shrinkable film are independently formed, the recycle release material is applied to either or both the inside surface of the label sleeve and the exterior surface of the container, the container is placed in the label sleeve and the label sleeve is shrunk so that the interior surface of the label and the exterior surface of the container are in intimate contact with the recycle release aid. The recycle release aid may also be incorporated into the label material.

Alternatively the shrinkable film sleeve could be applied to a container preform as described above. Once the label and preform are in intimate contact with the recycle release aid a container could be formed via any conventional method. Methods for Forming Multilayer Structures

The layers of the present invention can be formed by conventional methods such as extrusion, extrusion blow molding, injection molding, injection blow molding, stretch blow molding and the like. Methods for forming multilayer structures are known. Suitable methods include, either singly or in combination, coextrusion, including the processes disclosed in US 5,688,578; 5,582,851; 5,221,507; 5,040,963; 5,582,851; 5,098,274;4,923,723;5,582,788; 5,651,998; 5,143,733; 5,523,045; and the like, extrusion coating, solution coating, emulsion or latex or dispersion coating, solventless liquid coating methods whereby the coating is cured by exposure to ultraviolet light or to a flux of electrons or by reaction with atmospheric oxygen, vapor deposition, vacuum deposition, coinjection, injection overmolding, lamination, and the like. The above listed methods may be followed by or be preceded by one or more other processing operations such as stretching or drawing, thermoforming, blow molding, heat sealing, or other processing or fabrication techniques.

Alternatively the multilayer structure may be formed by separately forming a preform and a barrier sleeve or sock. The sleeve or sock could be inserted over the structural layer preform just prior to reheating the preform, The recycle release material or adhesion promoting material could be blended into the barrier material or coated on either the inner surface of the sleeve or the outer surface of the preform. Once the sleeve and preform are in intimate contact the container is formed via conventional blow molding methods. Variations of the methods described above, and other methods not fully described herein will be obvious to those skilled in the art. It should be appreciated that the containers and preforms of the present invention can be either single or multilayer.

The multilayer structures of the present invention comprises at least two disctinct layers and may have up to seven or more layers. The upper number is limited only by the desired thickness of the final article and the capabilities of the apparatus and method of formation which are chosen. Currently, equipment and processes for forming articles having up to seven layers, and preferably between 2 and 5 layers are readily available from a number of sources including Continental PET, Kortec, Hostetter and others. Similarly, the order of the layers, and the number of different layers may vary. Generally, if the article is to contain food or beverages it is preferred to have a structural layer which is approved for use in food contact applications as the layer which contacts the article contents. Thus, an advantageous multilayer structure would be one having a first structural layer which contacts the food, a performance layer and optionally a second structural layer forming the outside of the article. It should be appreciated that the structural layers can be formed from the same or different polymers. Similarly, the performance layers can be formed from the same or different polymers. Alternately, either or both of the structural layers could be performance layers which are suitable for food contact. Structural layers may also include recycled polymer content to reduce the cost of the finished container. In applications where extreme performance is necessary, four or five layer containers, having two performances layers (which may be the same or different) could also be envisioned. In such a multilayer structure it may be necessary or advantageous to incorporate more than one recycle release aid between/in various layers, or to incorporate the same material in different ways (ie blended into one layer, but interdisposed between others). The performance layers (P) could be incorporated as coninjected layers, as coated layers or a combination of the two. A four layer structure with a S- coinjected P- S- coated P structure is one example. An example of a suitable five layer structure is a S -P-S -P- S structure. Thus the present invention enables production of a variety of multilayer structures which display good physical properties, interlayer adhesion during use and improved recyclability. It is essential to the functioning of a multilayer package or container that the layers composed of dissimilar materials have sufficient adherence to one another to prevent delamination of the layers for the lifetime of the package. Depending on the composition of the layers and the method of manufacture, the layers may naturally have adequate adhesion for the intended application of the package. Conversely, the layers may have inadequate adhesion unless an effort specifically intended to improve interlayer adhesion is undertaken. Generally to prevent undesirable effects such as local delamination and/or separation during use it is necessary for the layers to have an interlayer adhesion of at least about 30 g/mm, and more preferably at least about 50 g/mm as measured by a t-peel test. The t- peel test is performed by first manually starting separation of the layers and then the free ends are inserted into the jaws of a testing machine such as an Instron. The bond is pulled apart and the force required to do so is measured. The average of this force represents the adhesive force between the structural and performance layers. Thus in one embodiment of the present invention at least one recycle release aid is added to improve the interlayer adhesion between two or more layers. The at least one recycle release aid may exist as a separate layer interposed between two other layers which do not naturally adhere (as a tie layer). Alternatively, the at least one recycle release aid may be used as an additive to either or both the structural and barrier layers, either via blending during the melt processing operation which forms the layer or in a separate compounding operation prior to the melt processing of the layer. The multilayer structures of the present invention are also readily recyclable. Post-use recycling of plastic packaging has become widespread in many parts of the world due to environmental and social concerns, in some jurisdictions it is required by law. The recycling of plastic packaging made from a single material is relatively straightforward: the packaging is simply chopped or ground, washed, and processed via either a melt ^•co ¬

processing operation or a chemical depolymerization process. The resultant material is similar to virgin polymer or monomer and consequently has significant utility.

Recycling conditions include generally grinding the bottles and washing the granulated material with warm to hot water for a period of time sufficient to shrink the polyester somewhat and remove contaminants such as dried beverage syrup, etc. This also facilitates removal of label stock from the bottle granulate as well. Detergents may also added to the washing water to facilitate cleaning of the final polyester flake. The recycling of multilayer packaging, however, is much more difficult.

The two or more materials which form the multilayer packaging are generally not compatible with one another when the used packaging is subsequently recycled. Moreover, when the distinct layers display good interlayer adhesion, separation of the layers for recycling is very difficult. Thus, the present invention has overcome a significant deficiency in the art. The multilayer structures of the present invention display good interlayer adhesion during forming and use and are readily separated in conventional recycling systems.

The multilayer structures are readily separated by contact with water, steam or other cleaning solutions which are commonly used in conventional recycling processes. Suitable cleaning solutions include water and water solutions containing detergents. It should be understood that the amount of time necessary to separate the layers will vary with the temperature and type of the cleaning solution used. As used throughout the phrase "improved separability under recycling conditions" means improved separation of the structural and performance layers when contacted with water or recycling cleaning solutions at temperatures from about ambient to about 100°C and for times ranging from about 1 min to about 1 hr. Current, agitation and other mechanical means may also be included in suitable recycling procedures. Most commonly, temperatures of above 50°C and more commonly above 60° C and most preferrably above 70°C are used for the recycling process with times of contact of preferrably at least 10 min and more preferrably at least 20 min.

The multilayer structures of the present invention overcome many of the deficiencies of current multilayer packaging including the formation of a recycled plastic multilayer blend having poor properties and severely limited utility. This deficiency cannot be overcome by depolymerization technology which yields a contaminated product which is generally not useful as-is and is difficult or impossible to purify. In certain embodiments the recycle release aids function as a tie layer between the two (or more) layers of the construction (regardless of whether those layers would have good or poor adhesion in the absence of the tie layer) during the lifetime of the package, do not interfere with the use of or degrade the utility of the package during its lifetime, and readily permit the separation of the various layers of the construction during recycling. Alternatively, in constructions in which the two (or more) layers do not naturally have adequate adhesion, recycle release material can be blended with one or more of the resins of the structural and/or barrier layers to promote adequate interlayer adhesion during the lifetime of the package and allow for easy layer separation during recycling.

The present invention may also be used to form multilayer closures.

Examples 1-4

EVOH copolymer (EVALCA grade EVAL-F101) and an amorphous thermoplastic polyester made from isophthalic acid, sodiosulfoisophthalic acid, diethylene glycol, and cyclohexanedimethanol (Eastman AQ 48) were dried separately in desiccant air dryers before making a pellet/pellet blend of 80% by weight EVOH and 20% by weight AQ 48. This was melt compounded in a 19mm APV twin-screw extruder using a high-shear screw construction. The measured melt temperature was 245°C. A strand was extruded onto a continuously moving belt, chopped into pellets, and the pellets were sealed in an air-tight steel can.

Portions of the compounded EVOH/AQ 48 blend were mixed with additional dried EVOH (EVALCA grade EVAL-F101) to make pellet/pellet blends of the following compositions: 75% by weight EVOH and 25% compounded blend, yielding an overall composition of 95% by weight EVOH and 5% AQ 48; and 50% by weight EVOH and 50% compounded blend, yielding an overall composition of 90% by weight EVOH and 10% AQ 48. Three-layer coextruded sheet was made using two one-inch Killion single-screw extruders fitted to a three-layer coextrusion feedblock. One extruder was used to plasticate and pump a bottle-grade poly(ethyiene terephthalate) (PET) resin (Eastman PET 9921W); this resin formed the outer two layers of the coextruded sheet. The other extruder was used to plasticate and pump an EVOH-based material, which formed the center layer of the three-layer coextruded sheet. Four different coextruded sheets were produced, differing by the composition of the center layer: (1) Pure EVOH (EVALCA grade EVAL-F101); (2) the EVOH/compounded blend mixture described above having an overall composition of 95% by weight EVOH and 5% by weight AQ 48; (3) the EVOH/compounded blend mixture described above having an overall composition of 90% by weight EVOH and 10% by weight AQ 48; and (4) the compounded blend composed of 80% by weight EVOH and 20% by weight AQ 48. The total thickness of the coextruded sheet was 20 to 24 mils, and the center layer made up 36% to 38% of the total thickness. The coextruded sheet having pure EVOH as the center layer was nearly free of haze, as determined by visual inspection. The coextruded sheet became progressively more hazy as the concentration of AQ 48 in the center layer increased. However, the haze was not extreme, even for the sheet with the highest level of AQ 48 (20% by weight) in the center layer: Black type of 8 point size on a white paper could be easily read through the coextruded sheet while the sheet was held one foot from the printed paper. The degree of adhesion between the central and the outer layers of the coextruded sheet was first characterized manually by initiating a delamination between the central layer and an outer layer and then peeling the layers apart. The coextruded sheet having pure EVOH as the center layer delaminated very easily, and little force was required to peel the layers apart. As the concentration of AQ 48 in the center EVOH-based layer increased, it became progressively more difficult to initiate delamination between the center and the outer layers, and progressively greater force was required to peel the layers apart.

This observation was quantified by carrying out T-peel force measurements on one inch wide strips of the coextruded sheets. The results are shown in Table 1 , below.

Table

Effect of AQ 48 Addition to EVOH on the Force Required to Peel the Center

EVOH-based Layer from an Outer PET Layer in a T-Peel Measurement

This clearly shows that adding AQ 48 to EVOH effectively and substantially increases the degree of adhesion between the EVOH-based and the PET layers. The peel strength was effectively doubled with as little as 5% adhesion promoting material added to the performance layer. Improvements of up to 450% were observed with only a small loss in clarity.

Examples 5-8

The procedures described in Example 1 were repeated, but the AQ 48 of Example 1 was replaced with Eastman AQ 55. AQ 48 and AQ 55 are manufactured from the same set of monomers; only the ratio of the two diacids and the ratio of the two diols differs in the two polyesters.

The coextruded sheet having pure EVOH as the center layer was nearly free of haze, as determined by visual inspection. The coextruded sheet became progressively more hazy as the concentration of AQ 55 in the center layer increased. However, the haze was not extreme, even for the sheet with the highest level of AQ 55 (20% by weight) in the center layer: Black type of 8 point size on a white paper could be easily read through the coextruded sheet while the sheet was held one foot from the printed paper. The degree of adhesion between the central and the outer layers of the coextruded sheet was first characterized manually by initiating a delamination between the central layer and an outer layer and then peeling the layers apart. The coextruded sheet having pure EVOH as the center layer delaminated very easily, and little force was required to peel the layers apart. As the concentration of AQ 55 in the center EVOH-based layer increased, it became progressively more difficult to initiate delamination between the center and the outer layers, and progressively greater force was required to peel the layers apart.

This observation was quantified by carrying out T-peel force measurements on one inch wide strips of the coextruded sheets. The results are shown in Table 2.

Table 2.

Effect of AQ 55 Addition to EVOH on the Force Required to Peel the Center

EVOH-based Layer from an Outer PET Layer in a T-Peel Measurement

This clearly shows that adding AQ 55 to EVOH effectively and substantially increases the degree of adhesion between the EVOH-based and the PET layers. Again, the peel strength was effectively doubled with only 5% adhesion promoting material included in the performance layer.

Example 9

Coextruded sheet of Example 4 (containing 20% by weight AQ 48) in the center EVOH-based layer was cut into strips approximately 0.5 inch wide and 1 inch long. These strips were placed into a beaker of water heated to approximately 85°C and gently stirred with a magnetic stir bar. The strips were removed from the water after approximately 20 minutes immersion. It was found that virtually no force was required to delaminate and peel apart the three layers of the coextruded sheet.

This demonstrates that exposure to hot liquid water essentially destroys the adhesive bond between coextruded PET and EVOH modified by the addition of AQ 48, allowing the layers to be easily separated and recycled.

Examples 9-12 The coextruded sheets of Examples 1-4 were biaxially oriented to a

4x4 ratio at 110°C using a T.M. Long film stretching machine. The sheet having pure EVOH as the central layer, which was nearly free of haze in as- extruded form, remained clear and free of haze upon orientation. Surprisingly and unexpectedly, the sheets containing AQ 48 in the EVOH- based center layer, which were very noticeably hazy in as-extruded form, also became clear and nearly free of haze upon orientation. The haze in the oriented films was measured analytically according to ASTM D-1003 using a Hunter Lab Ultrascan Colorimeter and the results are given in Table 3.

Table 3. Effect of AQ 48 Addition to EVOH on the Haze in Biaxiallv Oriented

Coextruded Sheet

Haze levels greater than 2% are unacceptable for most clear, colorless, food and beverage packaging. Even at 20% adhesion promoting material in the performance layer, the oriented film displayed sufficient optical clarity after biaxial orientation for use in consumer packaging.

Examples 13-16

The biaxially oriented films of example 9-12 were manually delaminated and peeled apart by hand. The oriented film having pure EVOH as the center layer delaminated easily and very little force was required to peel apart the layers. As the concentration of AQ 48 in the center EVOH- based layer increased, it became progressively more difficult to initiate delamination and the force required to peel apart the layers progressively increased. For the film having 20% by weight AQ 48 in the center EVOH- based layer, peeling the layers apart was difficult because the interlayer adhesion was so great that the outer PET layer repeatedly tore rather than cleanly peel away from the center layer.

Thus, the improved adhesion to PET resulting from the addition of an adhesion promoting material, such as AQ 48, is retained upon biaxial orientation. Example 17-20

The biaxially oriented films of example 9-12 were tested in duplicate for oxygen permeability at 30°C and about 50% relative humidity using an oxygen permeability tester manufactured by Modern Controls, Inc. The results are shown in Table 4.

Table 4 Oxygen Permeability of the Biaxially Oriented Coextruded Sheets

Thus, the addition of an adhesion promoting material, such as AQ 48 has no statistically significant effect on the oxygen barrier properties of the EVOH-based center layer. That is, the water dissipatible polymer does not degrade or diminish the bas barrier of the EVOH-based layer.

The foregoing Examples 1-20 clearly show that incorporation of an adhesion promoting material as disclosed in the present invention, significantly improves the interlayer adhesion between the performance and structural layers of the multilayer structure without detriment effect to significant end use requirements like clarity and barrier. Both the dramatic improvement in interlayer adhesion (at least about 100% at concentrations as low as 5% water dissipatible polymer), and the retention of acceptable clarity and barrier, were totally unexpected. Moreover, the ease with which the performance and structural layers could be separated when subjected to conventional recycling conditions was also surprising, especially when considered with the exceptional peel strength demonstrated at use conditions. Examples 20- 25

Three layer, multilayer preforms for 20 ounce containers were molded on Kortec multilayer equiment using PET (9921 W from Eastman Chemical Company) as the inner and outer structural layers. The central barrier performance layer was formed from EVOH or AQ-48/EVOH blends as shown in Table 5, below. Preforms with both a thick and thin barrier layer were molded. The preforms having an AQ/EVOH barrier layer were very noticeably hazy.

Table 5

These preforms were stretch blow molded on the Sidel SBO 2/3 into 20 ounce bottles. The bottles with an AQ/EVOH barrier layer blew well, having fewer striations and streaks in the central layer than bottles with a pure EVOH barrier layer. Sidewall haze was almost undetectable by eye in bottles having a thin layer of the 10% AQ blend (Example 8), but haze increased as the layer thickness or AQ concentration increased (Examples 9, 11 and 12).

The bottles were cut apart and layers of the sidewall were peeled apart by hand. The layers of the bottles from Examples 20 and 23 peeled apart readily. Interlayer adhesion was almost nonexistent in these bottles with an unmodified EVOH barrier layer.

The layers of the bottles from Examples 21 , 22, 24 and 25 were also peeled apart by hand. The adhesion between the layers of those bottles was much better than that in Examples 20 and 23. In some areas of the bottles of the present invention the interlayer adhesion was so strong that the outer PET layer tore before delamination occurred. No difference in interlayer adhesive strength was detected between the 10% and 20% AQ compositions, or the thin and thick layers.

The sidewalls cut from bottles of Examples 21 , 22, 24 and 25 were held under a stream of hot tap water. Within seconds, the layers spontaneously delaminated, usually completely, sometimes with a tiny tug to obtain complete separation.

Examples 26-31 The bottles from Examples 20-25 were evaluated for drop impact strength via the following method. Bottles (five of each type) were filled with water, then dropped squarely onto their petaloid base from successively greater heights until delamination of at least one "foot" of the base occurred. The initial drop height was 15 inches, and height was increased by 6 inches for each successive drop. Delamination was detected by gently indenting the side of each base foot. A delaminated foot makes a distinctive creaky squeaking sound when indented; an intact foot makes no sound. Results of the drop impact test are given in Table 6, below.

Table 6

All the bottles of the present invention showed significantly improved interlayer adhesion over the bottles having just an EVOH inner layer. The improvement in interlayer adhesion did not change dramatically at the two levels of adhesion promoting material used in Examples 27 and 28 (improvements of about 65 and about 55%, respectively). For bottles with the thick barrier layer, adhesion of the 20% AQ composition (Example 31) was significantly greater (about 300%) than that of the 10% AQ material (about 200%).

Example 32

This example illustrates the use of a barrier label on a bottle. Test specimens were prepared from 3 mil thick Mylar [DuPont trade name for biaxially oriented ρoly(ethylene terephthalate)]. Circles of aluminum foil, 52.4 mm in diameter (2.0625 in.) were coated with a 30 wt% solids water dispersion of a copolyester prepared from 89 mol% isophthalic acid and 11 mol% of 5-sodiosulfoisophthalic acid and 100 mol% of diethylene glycol to give an approximate film thickness of 12 microns (0.5 mils) when dried. The Mylar film was similarly coated. The two adhesive faces were placed together and pressed in a heated press at 85°C for 1 min. Testing of this assembly for C0₂ permeation rate gave 16.2 cc-mil/100 in²-da-atm. The control film permeation rate was 35.4 cc-mil/100 in²-da-atm. Thus the adhered specimen gave a 2.2 fold improvement over the control. Based on the area obscured in the testing apparatus, the theoretical improvement should be 2.12 times or within experimental error of functioning to reduce C0₂ permeation as a result of a simulated label with perfect barrier simply obscuring a portion of a bottle and preventing permeation of C0₂ through that portion of the bottle.

When this test assembly was cut into 5 mm by 5 mm squares and stirred in 85°C water for 35 min. to simulate recycling conditions, there was a complete separation of all of the aluminum foil from the Mylar film, thus indicating that this construction would allow for separation of a label from a bottle under recycling conditions. Comparative Example 33

This example illustrates that when an adhesive is used instead of an adhesion promoting material as contemplated by this invention, i.e., the performance layer fails to separate under simulated recycle conditions. Example 32 was repeated except that Lotader AX8900, (a copolymer of ethylene with 24 mol % methyl acrylate and 7 to 8 mol% glycidyl methacrylate, available from Elf Atochem) was used instead of a recycle release aid of the present invention. The adhesive film was cast out of a toluene-chloroform solvent mixture. The specimens were also cut into 5 mm by 5 mm squares are subjected to stirring in 85°C water for 35 minutes. At the end of the test, the aluminum foil was still perfectly adhered to the Mylar film illustrating that an adhesive that is not soluble or dispersible in water would cause a contamination problem in a recycle operation as the barrier label and the bottle would fail to be separated from one another.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention

Claims

We Claim:

1. A multilayer material comprising: a structural layer comprising at least one polymer; a performance layer which displays at least one physical property which is superior to said structural layer's physical properties; and at least one recycle release material which promotes interlayer release under recycling conditions, but maintains or improves interlayer adhesion between said structural and performance layers during use conditions.

2. The multilayer material of claim 1 wherein said structural layer and said performance layer which display poor interlayer adhesion to each other and said recycle release material provides interlayer adhesion between said structural and performance layers which is improved over the interlayer adhesion without said adhesion promoting material.

3. The multilayer material of claim 1 or 2 wherein said structural layer comprises one or more polymer which provides the mechanical and physical properties required of the package.

4. The multilayer material of claim 1 or 2 wherein said polymer comprises at least one polyester.

5. The multilayer material of claim 4 wherein said polyester comprises a dicarboxylic acid component comprising repeat units from terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl-2,6- naphthalenedicarboxylate, 2,6-naphthalenedicarboxylic acid, 1 ,2-, 1 ,3- and 1 ,4-phenylene dioxydoacetic acid and mixtures thereof and a glycol component comprising repeat units from ethylene glycol, diethylene glycol, 1 ,4-cyclohexane-dimethanol, 1 ,4-butanediol, and mixtures thereof.

6. The multilayer material of claim 5 wherein said dicarboxylic acid component repeat units are selected from the group consisting of terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, dimethyl- 2,6-naphthalenedicarboxylate and mixtures thereof.

7. The multilayer material of claim 5 wherein said dicarboxylic acid component further comprises at least one second dicarboxylic acid component repeat unit selected from the group consisting of aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms.

8. The multilayer material of claim 7 wherein said second dicarboxylic acid component repeat unit is selected from the group consisting of phthalic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'- dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and mixtures thereof .

9. The multilayer material of claim 5 wherein said glycol component further comprises a second gycol component repeat unit is selected from the group consisting of cycloaliphatic diols having 6 to 20 carbon atoms or aliphatic diols having 3 to 20 carbon atoms.

10. The multilayer material of claim 9 wherein said second glycol component repeat unit is selected from the group consisting of diethylene glycol, triethylene glycol, 1 ,4-cyclohexanedimethanol, propane-1 ,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1 ,6-diol, 3-methylpentanediol-(2,4), 2-methylpentanediol-(1 ,4), 2,2,4-trimethylpentane-diol-(1 ,3), 2- ethylhexanediol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol-(1 ,3), 1 ,4-di- (hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4- dihydroxy-1 ,1 ,3,3-tetramethyl-cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)- propane, 2,2-bis-(4-hydroxypropoxyphenyl)-propane, hydroxyethyl resourcinol and mixtures thereof.

11. The multilayer material of claim 4 wherein said dicarboxylic acid component repeat unit comprises at least about 70 mole% terephthalic acid and said glycol component repeat unit comprises at least about 70 mole % ethylene glycol.

12. The multilayer material of claim 1or 2 wherein said improved physical properties comprise gas barrier to migration, vapor barrier to migration, small molecule barrier to migration, barrier to light , heat resistance, stress crack resistance, impact resistance, heat distortion, sealing characteristics and mixtures thereof.

13. The multilayer material of claim 1 or 2 wherein said performance layer comprises a polymer selected from the group consisting of polyamides, saponified ethylene-vinyl acetate copolymer (EVOH), polyalcohol ethers, wholly aromatic polyesters, resorcinol diacetic acid-based copolyesters, polyalcohol amines, isophthalate containing polyesters, naphthalenedicarboxylate containing polyesters and mixtures thereof.

14. The multilayer material of claim 1 or 2 wherein said performance layer polymer further comprises platelet particles.

15. The multilayer material of claim 13 wherein said polymer comprises a polyamide selected from the group consisting of partially aromatic polyamides, aliphatic polyamides, wholly aromatic polyamides and mixtures thereof.

16. The multilayer material of claim 15 wherein said polyamide has a film forming molecular weight and an I.V. of greater than about 0.4.

17. The multilayer material of claim 15 wherein said wholly aromatic polyamide comprises at least 70 mole % of structural units derived from m-xylylene diamine or a xylylene diamine mixture comprising m-xylylene diamine and up to 30% of p-xylylene diamine and an -al iphatic dicarboxylic acid having 6 to 10 carbon atoms.

18. The multilayer material of claim 13 wherein said polymer comprises a polyamide formed from repeat units selected from the group consisting of sophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, meta- or para-xylylene diamine, 1,3- or 1 ,4-cyclohexane(bis)methylamine, aliphatic diacids with 6 to 12 carbon atoms, aliphatic amino acids or lactams with 6 to 12 carbon atoms, aliphatic diamines with 4 to 12 carbon atoms.

19. The multilayer material of claim 15 wherein said partially aromatic polyamides are selected from the group consisting of poly(m-xylylene adipamide), poly(hexamethylene isophthalamide), poly(hexamethylene adipamide-co-isophthalamide), poly(hexamethylene adipamide-co- terephthalamide), poly(hexamethyiene isophthalamide-co-terephthalamide) and mixtures thereof.

20. The multilayer material of claim 19 wherein said partially aromatic polyamide is poly(m-xylylene adipamide).

21. The multilayer material of claim 15 wherein said aliphatic polyamide is selected from the group consisting of poly(hexamethylene adipamide) and poly(caprolactam).

22. The multilayer material of claim 15 wherein said aliphatic polyamide is poly(hexamethylene adipamide).

23. The multilayer material of claim 15 wherein said aliphatic polyamides are selected from the group consisting of polycapramide (nylon 6), poly-aminoheptanoic acid (nylon 7), poly-aminonanoic acid (nylon 9), polyundecane-amide (nylon 11), polyaurylactam (nylon 12), polyethylene- adipamide (nylon 2,6), polytetramethylene-adipamide (nylon 4,6), polyhexamethylene-adipamide (nylon 6,6), polyhexamethylene-sebacamide (nylon 6,10), polyhexamethylene-dodecamide (nylon 6,12), polyoctamethylene-adipamide (nylon 8,6), polydecamethylene-adipamide (nylon 10,6), polydodecamethylene-adipamide (nylon 12,6), polydodecamethylene-sebacamide (nylon 12,8) and mixtures thereof.

24. The multilayer material of claim 12 wherein said EVOH comprises an saponified ethylene-vinyl acetate copolymer having an ethylene content of about 15 to about 60 mole % and a degree of saponification of between about 90 and about 100%.

25. The multilayer material of claim 13 wherein said polyalcohol ether is selected from the group consisting of phenoxy resins derived from reaction of hydroquinone and epichlorohydrin.

26. The multilayer material of claim 25 wherein sail polyalcohol ether comprises resorcinol units.

27. The multilayer material of claim 13 wherein said wholly aromatic polyesters are formed from repeat units comprising terephthalic acid, isophthalic acid, dimethyl-2,6-naphthalenedicarboxylate, 2,6- naphthalenedicarboxylic acid, hydroquinone, resourcinol, biphenol, bisphenol A, hydroxy benzoic acid, hydroxynaphthoic acid and mixtures thereof .

28. The multilayer material of claim 13 wherein said diacetic resourcinol copolymers comprise repeat units of 0 to about 95 mole% terephthalic acid, about 5 to about 100 mole % m-phenylenoxydiacetic acid, p-phenylenoxydiacetic or mixtures thereof and ethylene glycol.

29. The multilayer material of claim 13 wherein said polyalcohol amines comprise repeat units derived from a bisglycidal ether selected from resorcinol bisgylcidyl ether, hydroquinone bisglycidyl ether and mixtures thereof and alkanol amine.

30. The multilayer material of claim 13 wherein said isophthalate containing polyesters are selected from polyesters comprising repeat units derived from at least one carboxylic acid comprising isophthalic acid and at least one glycol comprising ethylene glycol.

31. The multilayer material of claim 13 wherein said naphthalenedicarboxylate containing polymers include polyesters comprising repeat units derived from at least one carboxylic acid comprising naphthalene dicarboxylic acid and at least one glycol comprising ethylene glycol.

32. The multilayer material of claim 1 or 2 wherein said recycle release aid is selected from the group consisting of water soluble polymers, water dispersible polymers, hydrophyllic polymers, hydrolytically unstable polymers, polymers which are labile under recycling conditions and mixtures thereof.

33. The multilayer material of claim 1 or 2 wherein said recycle release aid is selected from the group consisting of water soluble polymers, water dispersible polymers and mixtures thereof.

34. The multilayer material of claim 32 wherein said water soluble polymers dissolve readily in water and are selected from the group consisting of polyvinyl alcohol, polyvinylpyrollidone, polyacrylic acid, methacrylic acid and mixtures thereof.

35. The multilayer material of claim 32 wherein said water dispersible polymers form electrostatically-stabilized colloids when mixed with water.

36. The multilayer material of claim 35 wherein said water-dispersible polymers have an inherent viscosity of at least about 0.1 dUg, when determined at 25┬░C using 0.25 g polymer per 100 ml of a solvent consisting of 60 parts by weight phenol and 40 parts by weight tetrachloro-ethane.

37. The multilayer material of claim 35 wherein said water-dispersible polymers have an inherent viscosity of about 0.28-about 0.38 dL/g.

38. The multilayer material of claim 35 wherein said water-dispersible polymers are selected from the group consisting of sulfonate-containing, water-dispersible, linear polymers, starch, thermoplastic starch, carboxymethyl cellulose and mixtures thereof.

39. The multilayer material of claim 35 wherein said water-dispersible polymers are selected from the group consisting of sulfonate-containing, water-dispersible, linear polymers comprising repeating, alternating residues of (1) one or more dicarboxylic acids and (2) one or more diols or a combination of one or more diols and one or more diamines where, in the preceding definition, the mole percentages are based on 100 mole percent dicarboxylic acid residues and 100 mole percent diol or diol and diamine residues.

40. The multilayer material of claim 39 wherein said linear polymers further comprise residues of monomers having mixed functionality selected from the group consisting of hydroxycarboxylic acids, aminocarboxylic acids, aminoalkanols and mixtures thereof.

41. The multilayer material of claim 39 wherein said linear polymer diol comprises poly(ethylene glycol), and at least a part of said total is one or more of said monomer components substituted with one or more sulfonate metal salt groups.

42. The multilayer material of claim 35 wherein said water-dispersible polymers have an inherent viscosity of about 0.28 to 0.38 dl_/g and are comprised of:

(i) diacid monomer residues comprising about 60 to about 84 mole percent isophthalic acid monomer residues and about 16 to about 30 mole percent 5-sodio-sulfoisophthalic acid monomer residues; and (iii) diol monomer residues comprising about 45 to about 80 mole percent diethylene glycol monomer residues and about 20 to about 55 mole percent ethylene glycol, 1 ,4-cyclohexanedimethanol monomer residues or mixtures thereof.

43. The multilayer material of claim 35 wherein said difunctional sulfomonomer component of the polyester is selected from the group consisting of dicarboxylic acid or an ester thereof containing a metal sulfonate group, a glycol containing a metal sulfonate group and a hydroxy acid containing a metal sulfonate group.

44. The multilayer material of claim 35 wherein said metal ion of the sulfonate salt is selected from the group consisting of Na+, Li+, K+ and mixtures thereof.

45. The multilayer material of claim 35 wherein said water-dispersible polymers said wherein the sulfonate salt group is attached to an aromatic acid nucleus such as benzene, naphthalene, diphenyl, oxydiphenyl, sulfonyldiphenyl or methylenediphenyl nucleus.

46. The multilayer material of claim 35 wherein said difunctional sulfomonomer component is 5-sodiosulfoisophthalic acid or its esters, and the glycol is a mixture of ethylene glycol or 1,4-cyclohexanedimethanol with diethylene glycol.

47. The multilayer material of claim 35 wherein said water-dispersible polymers is composed of 80 mole parts of isophthalic acid, 10 mole parts of adipic acid, 10 mole parts of 5-sodiosulfoisophthalate, 20 mole parts of ethylene glycol and 80 mole parts diethylene glycol.

48. The multilayer material of claim 1 or 2 wherein said recycling release aid is incorporated into said performance layer or disposed between said performance layer and said structural layer.

49. The multilayer material of claim 1 or 2 wherein said material further comprises a label which is disposed on at least a portion of an outer surface of said material.

50. The multilayer material of claim 49 wherein said label is one of said performance layers.

51. The multilayer material of claim 50 wherein said label comprises barrier materials selected from the group consisting of polyamides, saponified ethylene-vinyl acetate copolymer (EVOH), polyalcohol ethers, wholly aromatic polyesters, resorcinol diacetic acid-based copolyesters, polyalcohol amines, isophthalate containing polyesters, naphthalenedicarboxylate containing polyesters and mixtures thereof, conventional label materials selected from the group consisting of polypropylene or copolymers thereof any of which may be optionally modified with barrier enhancing platelet particles, inorganic materials and mixtures thereof.

52. The multilayer material of claim 51 wherein said inorganic material is selected from the group consisting of metal foil, a metal oxide coating, silicate based coatings and mixtures thereof.

53. The multilayer material of claim 51 wherein said inorganic material is selected from the group consisting of aluminum, Al₂0₃ .

54. The multilayer material of claim 51 wherein said label is applied by a method selected from the group consisting of laminating at least a portion of an outer surface of said multilayer material with said label; depositing as a layer said label onto said multilayer material; adhering said label to said multilayer material; coforming said label concurrent with forming an article of said multilayer material and combinations thereof.

55. The multilayer material of claim 49 wherein said recycling release aid is disposed between said molded article and said label.

56. A shaped or molded article comprising the multilayer material of claim 1 or 2.

57. The shaped or molded article of claim 56 wherein said article is selected from the group consisting of fiber, film, sheet, preforms, profiles, tubing, pipes and containers.

58. The shaped or molded article of claim 56 wherein said article is a container or a preform.

59. The shaped or molded article of claim 56 or 58 wherein said article comprises at least three layers.

60. The shaped or molded article of claim 59 wherein said article comprises five layers.

61. The shaped or molded article of claim 59 or 60 wherein said second layer comprises a performance layer and is disposed between said first and third layers.

62. The shaped or molded article of claim 59 wherein said first layer comprises a structural layer.

63. The shaped or molded article of claim 60 wherein said second and fourth layers comprises performance layers and said first, third and fifth layers comprise structural layers.

64. The shaped or molded article of claim 63 wherein said third layer comprises recycled PET.

65. The shaped or molded article of claim 58 wherein said performance layer is an independently formed sleeve applied to at least a portion of said structural layer.

66. The shaped or molded article of claim 65 wherein said recycle release material is applied to an inside surface of said sleeve, an exterior surface of said preform or container or both.

67. The shaped or molded article of claim 65 wherein said performance layer further comprises said recycle release material.

68. A method for forming a multilayer article comprising forming a structural layer comprising at least one polymer; a performance layer which displays at least one physical property which is superior to said structural layer's physical properties; wherein said structural layer and performance layer display poor interlayer adhesion to each other and incorporating into said multilayer structure at least one recycle release aid which provides interlayer adhesion between said structural and performance layers which is improved over the interlayer adhesion without said recycle release aid.

69. The method of claim 68 wherein said improved interlayer adhesion is at least about 30 g/mm as measured by a t-peel test.

70. The method of claim 69 wherein said improved interlayer adhesion is at least about 50 g/mm.

71. The method of claim 68 wherein said recycle release aid is incorporated 2 wherein said recycle release aid is incorporated into said performance layer or disposed between said performance layer and said structural layer.

72. A method for forming a multilayer article comprising forming a structural layer comprising at least one polymer; a performance layer which displays at least one physical property which is superior to said structural layer's physical properties; wherein said structural layer and performance layer display good interlayer adhesion to each other and incorporating into said multilayer structure at least one recycle release material which promotes interlayer release under recycling conditions, but maintains interlayer adhesion between said structural and performance layers during use conditions.

73. The method of claim 72 wherein said recycling conditions comprise contact with water, water solutions containing detergents, steam and the like at temperatures from about ambient to about 100┬░C and for times ranging from about 1 min to about 1 hr.

74. The method of claim 73 wherein said recycling conditions include introduction of current, agitation, blowing and other mechanical means.

75. The method of claim 73 wherein said temperatures are above about 50┬░C.

76. The method of claim 73 wherein said temperatures are above about 60┬░C.

77. The method of claim 73 wherein said temperatures are above about 70┬░C.

78. The method of claim 73 wherein said time is at least about 10 minutes.

79. The method of claim 73 wherein said time is at least about 20 minutes.