Combinations of polymers are commercially important because of their potential to combine valuable attributes of a number of different polymers. Blending polymers can give desirable combinations of attributes such as barrier and cost, chemical resistance and dimensional stability, and toughness and strength. Some examples of applications in which multilayer structures of two or more polymers are widely used include barrier packaging and pipe applications where the barrier properties of one material are combined with the mechanical properties of less expensive materials.

Most polymer combinations have poor miscibility resulting in blends that are not a single phase. Non- miscible polymers frequently do not have enough interaction to generate strong interfacial bonding. This weak interfacial bonding can lead to delamination and loss of properties. Compatibilization of the polymer/polymer interface refers to lowering interfacial tension or improving the physical or chemical interaction of the polymers in combination. Compatibilization is of high importance since it leads to the strong interfacial bonds necessary to achieve and maintain the desired properties of the combination. For example, it prevents or reduces the ingress of water and other liquids such as hydrocarbons.

Polymers of carbon monoxide and olefinically (i. e., ethylenically) unsaturated hydrocarbons commonly referred to as aliphatic alternating polyketones (hereafter,

"polyketones"or"polyketone polymers") are now well known. High molecular weight alternating aliphatic polyketones are of considerable interest because they exhibit a good overall set of physical and chemical properties. They have excellent mechanical properties, chemical resistance, and barrier properties which makes them particularly attractive for use in combination with other polymers. This class of polymers is disclosed in e. g. US-A-4880903 and US-A-5369170.

US-A-5369170 discloses a polymer composition which is a combination of a polyketone polymer, a polymer which is not miscible with the polyketone, and a compatibilizing polymer obtainable by reacting a diamine with a polymer having carboxyl groups. A maleic anhydride graft copolymer reacted with a diamine having two primary amino groups is such a compatibilizer. Graft or copolymerized acid copolymers (e. g., acrylic acid copolymers) also contain such compatibilizers. Further refinements of this technology are discussed by Ash et. al. in"Bonding Aliphatic Polyketones to Incompatible Polyolefin Polymers, Research Disclosures", January 1997, pp. 11,12 (Kenneth Mason Publications).

US-A-5637410 is directed to adhesive blends of polyolefins. The blends are carboxylic acid derivative graft polymers and a low density polyethene reacted in the presence of a diamine. The preferred graft polymer is a maleic anhydride graft polyethene. Multilayer structures made of these blends together with polyketones are also described.

The polymer compositions of US-A-5369170 can be produced in the form of a blend obtained by a melt blending process. In this type of process the compatibilizing polymer is thought to be present as a layer between the polyketone phase and the polymer phase to which it is bound. Multilayer structures which

include the compatibilizing polymer as a tielayer can be prepared by co-extrusion to make such articles as multilayer pipes and multilayer sheets and films. The compatibilizing polymer can also be used as a coating layer for a polyketone object, in which case no second polymer need be present.

The preparation and use of the compositions of US-A- 5369170 and US-A-5637410 is not trouble free. For example, when the compatibilizers contain maleated polymers, a stoichiometric excess of amine is typically required. Further, when the compatibilizers contain carboxylic acid groups, cf. US-A-5369170, lengthy processing times in the melt can lead to increases in melt viscosity and a tendency to form gels. This can lead to poor melt stability, the formation of bubbles or lumps and an uneven distribution of layers in multilayer structures resulting in the so-called wave pattern in processed polymer. Further, the gels may deteriorate polymer performance by, for example, acting as stress concentrators thereby decreasing impact resistance.

Without being bound to theory, it is believed that melt stability problems are caused by cross-linking.

Recently it has been found (cf. PCT application PCT/EP99/01001, not pre-published) that improvements to polyketone compositions can be obtained by employing a compatibilizing polymer which is the reaction product of a particular type of amine and a polymer containing carboxylic acid groups (i. e., hydroxycarbonyl groups).

The amine contains a primary amino group which is attached to an aliphatic carbon atom which carries at most one hydrogen atom. This affords some measure of steric hindrance to the amine. Compositions made from this combination show a reduced tendency to cross-link in the melt, while the interfacial attraction of the

materials used in this combination is acceptable for many applications.

Additional methods and compositions for combining polyketones with different polymers that lessen the propensity towards crosslinking and poor melt stability yet display improved interfacial attractions would enhance the utility of polyketones. This is particularly true in the case of multilayer structures and articles made from them.

The invention is a composition containing (a) a polyketone, (b) optionally a second polymer which is not miscible with the polyketone, and (c) an amine modified hindered carboxylic acid copolymer which is based on a hindered carboxylic acid copolymer which contains at most 2.04 mole% hindered carboxylic acid monomer units, based on the number of moles of carboxylic acid monomer units relative to the total number of moles of monomer units present in the hindered carboxylic acid copolymer.

The invention is also a process for preparing a polymer compositions which process comprises at least the step of contacting the polyketone, and optionally the second polymer, with the amine modified hindered carboxylic acid copolymer.

In addition, the invention is a kit of parts containing a part of the polyketone, optionally a part of the second polymer, and a part of the amine modified hindered carboxylic acid copolymer.

The polyketone polymers which are employed in this invention are of an alternating structure and contain substantially one monomer unit of carbon monoxide for each monomer unit of olefinically unsaturated hydrocar- bon. The monomer units of the polymer attributable to

carbon monoxide alternate with those attributable to the olefinically unsaturated hydrocarbon.

It is possible to employ a number of different olefinically unsaturated hydrocarbons as monomers within the same polymer but the preferred polyketone polymers are copolymers of carbon monoxide and ethene or terpolymers of carbon monoxide, ethene and a second olefinically unsaturated hydrocarbon of at least 3 carbon atoms, particularly an a-olefin such as propene.

Additional monomers can also be used and still come within the scope of polyketone polymers described herein.

That is, polyketone polymers can be made from four, five, or more combinations of monomers. Such polyketone polymers are aliphatic in that there is an absence of aromatic groups along the polymer backbone. However, alternating polyketones may have aromatic groups substituted or added to side chains and yet still be considered alternating aliphatic polyketones.

When the preferred polyketone terpolymers are employed, there will be within the terpolymer at least 2 units incorporating a moiety of ethene for each unit incorporating a moiety of the second or subsequent hydrocarbon. Preferably, there will be from 10 units to 100 units incorporating a moiety of the second hydrocar- bon. The polymer chain of the preferred polyketone polymers is therefore represented by the repeating formula -p-CO-+-CH2-CH2) lx--+-CO---G) ly where G is the moiety of olefinically unsaturated hydrocarbon of at least three carbon atoms polymerized through the olefinic unsaturation and the ratio of y: x is no more than 0. 5. When copolymers of carbon monoxide and ethene are employed in the compositions of the invention, there will be no second hydrocarbon present and the

copolymers are represented by the above formula wherein y is zero. When y is other than zero, i. e. terpolymers are employed, the -CO (CH2-CH2) units and the -CO--G- units are found randomly throughout the polymer chain, and preferred ratios of y: x are from 0.01 to 0.1. The precise nature of the end groups does not appear to influence the properties of the polymer to any consid- erable extent so that the polymers are fairly represented by the formula for the polymer chains as depicted above.

Of particular interest are the polyketone polymers of number average molecular weight from 1000 to 200,000, particularly those of number average molecular weight from 20,000 to 90,000 as determined by gel permeation chromatography. The physical properties of the polymer will depend in part upon the molecular weight, whether the polymer is a copolymer or a terpolymer, and in the case of terpolymers the nature of the proportion of the second hydrocarbon present. Typical melting points for the polymers are from 175 °C to 300 °C, more typically from 210 °C to 270 °C, as measured by differential scanning calorimetry (DSC). The polymers have a limiting viscosity number (LVN), measured in m-cresol at 60 °C in a standard capillary viscosity measuring device, of from 0.5 dl/g to 10 dl/g, more frequently of from 0.8 dl/g to 4 dl/g. The backbone chemistry of aliphatic polyketones precludes chain scission by hydrolysis. As a result, they generally exhibit long term maintenance of their property set in a wide variety of environments.

The production of polyketone polymers is described in US-A-4808699 and US-A-4868282. US-A-4808699 teaches the production of linear alternating polymers by contacting olefinically unsaturated compounds and carbon monoxide in the presence of a catalyst containing a Group VIII metal compound, an anion of a non-hydrohalogenic acid with a pKa

less than 6 and a bidentate phosphorous, arsenic or antimony ligand. US-A-4868282 teaches the production of linear alternating terpolymers by contacting carbon monoxide and ethene in the presence of one or more hydrocarbons having an olefinically unsaturated group with a similar catalyst.

The optional, second polymer may be an addition polymer or a condensation polymer. Where an addition polymer is used, preferably it is a polymer of one or more olefinically unsaturated compounds (i. e., a compound having carbon-carbon double bonds) polymerized through their olefinic unsaturation (or as a result of a rearrangement of the unsaturation during polymerization); for example, ethene, propene, butene-1, styrene, methyl (meth) acrylate, vinyl acetate or combinations thereof.

Preferably the polymer contains C1-10 olefinically unsaturated hydrocarbon monomer units; the well known polyolefins such as polyethene, polypropene, poly (butene- 1) and polystyrene are preferred among this group, in particular polyethene and polypropene. High density polyethene (HDPE), (i. e., having a density greater than 930 kg/m3) is desirable. Low density polyethene and linear low density polyethene (i. e., having a density less than 930 kg/m3 are also suitable. Isotactic polypropene is the preferred polypropene. Condensation polymers include, for example, polyamides such as polyamide-6, polyamide-6,6, polyamide-11 and polyamide- 12, and poly (phenylene oxide). Another class of polymers useful as the second polymer of this invention are functionalized polymers wherein the functionality is reactive with amine component. Carboxylic acid copolymers and derivatives thereof such as maleated polypropene, maleated styrene, and maleated polybutylene are examples of such second polymers.

The weight average molecular weight of the second polymer is in the range of 2,000-1, 000,000, preferably 10,000-500, 000, as determined by gel permeation chromatography. The crystalline melting point is 80 °C to 300 °C, as measured by DSC, or, if the second polymer does not possess a crystalline melting point, its glass transition temperature is -80 to 200 °C, as measured by DSC.

If the optional second polymer is present, the amine modified hindered carboxylic acid copolymer preferably has good compatibility with the second polymer. For example, if the second polymer is a polyolefin, it would be preferred that the amine modified hindered carboxylic acid copolymer is a polyolefin which contains carboxylic acid groups. On the other hand, if the second polymer is a poly (phenylene-oxide), it would be preferred that the amine modified hindered carboxylic acid copolymer is a polymer such as a polystyrene having hindered carboxylic acid groups.

The amine modified hindered carboxylic acid copolymer may be prepared by melt blending a carboxylic acid copolymer with a suitable amine. The carboxylic acid copolymer is a copolymer in which at least one of the monomer units used to make the polymer is an olefinically unsaturated carboxylic acid. The alpha carbon (with respect to the hydroxycarbonyl group) of the carboxylic acid monomer is bonded to a functional group, in particular a Cl_6 alkyl group, and is not directly bonded to a hydrogen atom ; polymers made of such compositions are referred to herein as hindered carboxylic acid copolymers and offer significant advantages when applied in combination with polyketones, as described throughout this specification.

Although monocarboxylic acids are preferred monomers for the carboxylic acid copolymer, the acid monomer may be based on a polycarboxylic acid such as a dicarboxylic acid or a tricarboxylic acid. The other monomer units of the carboxylic acid copolymer are preferably olefinically unsaturated hydrocarbons such as one or more of the following: ethene, propene, butene-1, styrene, methyl (meth) acrylate, and vinyl acetate. Random copolymers of ethene or propene and R-CH=CRl-C02H, wherein R represents hydrogen or a C1-10 hYdrocarbyl group, in particular an alkyl group, and R1 is a C1_6 alkyl group are the preferred carboxylic acid copolymers of this inventions with random poly (ethene-methacrylic acid) and random poly (propene-methacrylic acid) being the most preferred carboxylic acid copolymers, particularly where the optional second polymer contains polyethene or polypropene respectively.

The carboxylic acid content of the carboxylic acid copolymer is low, for example at most 2.04 mole%. The carboxylic acid content is typically 0.015-2. 04 mole%.

Preferably, the carboxylic acid content is 0.34-1. 73 mole% and more preferably, 1.15-1. 55 mole%.

These contents apply in particular in the preferred embodiment of this invention in which the carboxylic acid copolymer is an ethene-methacrylic acid copolymer. All references to mole% carboxylic acid content herein are based on a calculation of the number of moles of the carboxylic acid monomer units, i. e. units having a hydroxycarbonyl group, relative to the total number of moles of all monomer units forming the polymer. It will be appreciated that a low molar content of carboxylic acid monomer units (qualifying as low carboxylic acid copolymer) can be attained by intermixing various quantities of carboxylic acid copolymer such that the

mole% acid content is in accord with the foregoing percentages based on the total carboxylic acid content for the carboxylic acid copolymer blend.

The melt flow index of the hindered carboxylic acid copolymer is typically 0.1-35. 0 g/10 min (based on ASTM D1238). Melt flow indices of 0.5-7 are preferred with 1-4 being most preferred, because this leads to better bonding between layers. Throughout this patent document the melt flow index specified is deemed to be based on measurements at 190 °C, applying a load of 2.16 kg and a die of 2.1 mm diameter and 8 mm length.

The weight average molecular of the carboxylic acid copolymer is typically 2000-1,000, 000 as determined by gel permeation chromatography. The crystalline melting point of the carboxylic acid copolymer is typically 80-300 °C (as measured by DSC) with 80-220 °C being preferred. If the carboxylic acid copolymer does not have a crystalline melting point, its glass transition temperature is -80 to 200 °C (as measured by DSC). These parameters are preferably met through the use of poly (ethene-methacrylic acid) available from DuPont as "NUCREL" (NUCREL is a trademark) acid copolymers and having a carboxylic acid content of 4 %wt and a melt flow index of 3-7.

The amine component of the amine modified hindered carboxylic acid copolymer has at least two amine functional groups and is of the general formula NH2-R-NH2 wherein R is a bivalent C4_24 hydrocarbylene group which contains substituted or unsubstituted aliphatic, cycloaliphatic, or aromatic groups or combinations thereof and may contain hetero atoms such as Si, S, N, and O. Depending upon the composition of R, more than two amino groups may be present in the amine. It is most preferred that the amine component is an unhindered

primary diamine. For the purposes of this specification, an unhindered amine component is an amine of the formula above wherein the carbon atoms to which the said two primary amino groups, in particular all amino groups present, are attached carry two hydrogen atoms. The use of an unhindered amine component leads to better bonding between layers. A few examples of suitable amines are 4, 9-dioxadiamino-1, 12-dodecane; 1,4-diaminobutane ; 1,10-diaminodecane ; 4,4'-diaminodiphenyl ether; 1, 12-diaminododecane ; 1,7-diaminoheptane ; 1, 6-diaminohexane ; 1,3-diamino-2-hydroxypropane ; 2, 3-diaminonapthalene ; 1,8-diaminooctane ; 1, 5-diaminopentane ; 1,3-diaminopropane ; and 1,4-diamino-2-butanone. It is possible to use the amine in a wholly or partly neutralized form, i. e. as a salt of an acid. One or more amines can be used in combination.

Additionally, the amine component can be a reagent which produces an amine of the type described above upon further chemical reaction such as hydrolysis. For example, imine reagents which produce amines upon contact with water can also be used to prepare the amine modified hindered carboxylic acid copolymers used in this invention.

An effective amount of the amine component is used to achieve the desired level of adhesion. The quantity of the amine is preferably low. While a stoichiometric excess of carboxylic acid copolymer can be used it is a particular advantage of this invention that as little as 0.01 mole amine/mole of carboxylic acid (in the carboxylic acid copolymer) can be used with good effect in some applications. A skilled person will recognize applications in which greater amounts of adhesion are required and will increase the relative proportion of amine accordingly. However, maximum adhesion is generally attained through the addition of no more than a

stoichiometric quantity of amine. Good results can be achieved when the molar ratio of the amine component over the quantity of carboxylic acid in the hindered carboxylic acid copolymer is typically in the range of 0.01 to 0.5, more typically 0.012 to 0.25.

The amine modified hindered carboxylic acid copolymer of this invention may be made by melt blending the carboxylic acid copolymer with the amine by any suitable means, for example via extruder or Brabender mixer.

Suitable temperatures for melt blending are above 100 °C, typically above 120 °C, but generally below 300 °C. A preferred temperature range is 150-220 °C. If desirable, the preparation of the amine modified hindered carboxylic acid copolymer may be effected simultaneously with a melt processing step which is carried out when preparing the composition of this invention as set forth below. It is also possible to perform the reaction between the amine and the third polymer by heating the reactants dissolved in a suitable solvent, for example, p-xylene, diethyleneglycol dimethylether and triethylene glycol dimethylether.

The polymer compositions of this inventions can be obtained by contacting the polyketone and (optionally) the second polymer with the amine modified hindered carboxylic acid copolymer. Reaction of the polyketone with the amine modified hindered carboxylic acid copolymer typically requires temperatures above 100 °C but generally below 300 °C.

In one embodiment, the polymer composition of this invention is in the form of a blend, in which the amine modified hindered carboxylic acid copolymer acts as a compatibilizer. Such blends can be made by any melt blending process which affects an intimate blending of the components of the composition. Such processes are well known to the skilled person and include, for

example, extrusion and combination in a Brabender mixer.

The weight ratio of polyketone to the second polymer may be within a broad range, for example between 5/95 and 95/5. Preferably, the range is between 10/90 and 90/10.

A range between 20/80 and 80/20 is more preferred. The quantity of the amine modified hindered carboxylic acid copolymer will generally relate to the quantity of the polyketone or of the second polymer if used as the minor component. Generally, it will contain 1-40 %wt (based on weight of the minor component) with 2-20 %wt being preferred.

In the preferred embodiment of this invention the polymer composition is in the form of a multilayer structure, in which the polyketone forms a first layer, the second polymer forms a second layer, and both layers are bonded together by an intermediate layer of the amine modified hindered carboxylic acid copolymer, functioning as an adhesive layer. Compositions having four or more layers may also be formed with additional intermediate layers.

Such multilayer structures can be made, for example, by extruding a melt of the amine modified hindered carboxylic acid copolymer in between the first and second layers which may be heated, e. g., at a temperature above 100 °C but below 270 °C simultaneously or in a later stage, thus effecting interfacial bonding. Other methods such as compression moulding and co-injection moulding can also be used. The most preferred method of making multilayer structures is a co-extrusion process in which a melt of the amine modified hindered carboxylic acid copolymer is extruded between a melt of polyketone and a melt of the second polymer. In such a co-extrusion process, the three melts are brought together in a suitable multilayer manifold prior to exiting the die.

The manifold is kept at a temperature of at least 150 °C,

preferably at least 180 °C but, generally less than 300 °C. The most preferred range is 200-280 °C. In the manifold the temperature is generally the highest of the extrusion temperatures. The total residence time in the manifold can vary from less than one minute to more than ten minutes. It is preferred that polymer having similar melt viscosities at the prevailing conditions be used.

Making more extensive multilayer structures will require more streams of polymer melts be guided into the multilayer manifold. For example, a composite can be made from a layer of polyethene followed by a layer of amine modified hindered carboxylic acid copolymer, followed by a layer of polyketone regrind, followed by a layer of amine modified hindered carboxylic acid copolymer, followed polyethene regrind. Such composites improve the economics of multilayer constructions by using regrind layers but also permit the manufacturer to recognize the advantages of the properties of polyolefins together with those of polyketones.

The multilayer structures may be processed further, for example, through regrind, by bending (e. g., tubes, pipes), by stretching (e. g., of sheet to form film) or by thermoforming or blow moulding (e. g., to form a container).

In the multilayer structures of this invention, the thickness of the first and second layer will depend on application driven requirements. For example, the thickness may range from 5-5000 m, for example, in a film or sheet application, to 0.1-100 mm in tubing and pipe applications. The thickness of the intermediate layer will frequently range of from 5 to 1000 f-im.

In another embodiment of this invention, no second layer is present. For example, the amine modified hindered carboxylic acid copolymer can be applied

directly to a polyketone layer (or vice versa) to be used as a coating. This can be done in any form in which either polymer may take. For example, tubes, pipe, and sheet can all be coated in this way.

In yet another embodiment of this invention, a multilayer structure is formed in which the amine modified hindered carboxylic acid copolymer is used as an adhesive between a layer of polyketone and a layer of another material which is not a thermoplastic polymer, for example glass, metal (such as aluminium or copper), or a thermosetting resin (such as a phenol-formaldehyde resin). The considerations and conditions described above wherein a second polymer is used apply to the embodiments in which no second polymer is used.

Additionally, successive applications of powder coatings of polyketone and amine modified hindered carboxylic acid copolymer can also be used to adhere the combination to the surface of a substrate using well known powder coating techniques.

The polyketone, the second polymer, and the amine modified hindered carboxylic acid copolymer may contain additives such as reinforcing fillers, non-reinforcing fillers, stabilizers, extenders, lubricants, pigments, plasticizers, and other polymeric materials to improve or otherwise alter its properties.

The compositions of this invention display excellent adhesion and an absence of gels, bubbles, or lumps. They also exhibit excellent performance properties such as impact resistance, chemical resistance and barrier properties. Multilayer structures can be formed with a good thickness of the various layers and do not show delamination in the presence of water or hydrocarbons.

The parts of the kit of parts suitable for producing the polymer compositions according to this invention may contain any of the polymers in any suitable form. For

example, liquids, powders, crumbs, and nibs are all suitable for this purpose.

The invention is further described by the following non-limiting examples.

Example 1 (Polyketone Formation) A terpolymer of carbon monoxide, ethene, and propene was produced in the presence of a catalyst composition formed from palladium acetate, the anion of trifluoroacetic acid and 1,3-bis (diphenylphosphino) - propane. The melting point of the linear terpolymer was 220 °C and it had an LVN of 1.75 dl/g, measured at 60 °C in m-cresol.

Examples 2-9 Various combinations of amine modified carboxylic acid copolymers were co-extruded with polyketones of Example 1 to form multilayer tubes. The outer layer was a high density polyethene commercially available from Petrothene as"LM60070"polyethene. The polyketone comprised the inner layer ; the amine modified carboxylic acid copolymers were the tielayers.

Acid copolymer 1 is a random poly (ethene-methacrylic acid) copolymer having 3.11 mole% carboxylic acid content and a melt flow index of 3 and is commercially available from Du Pont as"NUCREL 903"polymer. Acid copolymer 2 is a random poly (ethene-methacrylic acid) copolymer having 1.34 mole% carboxylic acid content and a melt flow index of 7 and is commercially available from Du Pont as "NUCREL 407"polymer. Acid copolymer 3 is a random poly (ethene-methacrylic acid) copolymer having 1.34 mole% carboxylic acid content and a melt flow index of 3 produced by Du Pont. Acid copolymer 4 is a random poly (ethene-acrylic acid) having a carboxylic acid content of 1.19 mole% and a melt flow index of 11 commercially available from Dow Chemical Co. as "PRIMACORE 3150" (PRIMACORE is a trademark) polymer.

Amine A is 4,9-dioxadiamino-dodecane commercially available from BASF as"DODA" (DODA is a trademark) amine. Amine B is bis (4-aminocyclohexyl) methane commercially available as"AMICURE PACM" (AMICURE is a trademark) amine from Air Products. The amine modified carboxylic acid copolymers were made by compounding the acid copolymers with a respective amount of diamine, as indicated in the Table, on a 25 mm twin screw extruder operated at a melt temperature of 160 °C. Pellets were produced by cooling the polymer leaving the extruder in a water bath and then strand cutting.

The multilayer co-extrusion was conducted using three single screw extruders (two 38 mm extruders and one 25mm extruder) and a multilayer manifold and tubing die. A tubing of nominal outer diameter of 7.5-8. 0 mm was produced with layer thicknesses of 0.46 mm (18 mil), 0.076-0. 10 mm (3-4 mil), and 0.41 mm (16 mil) for high density polyethene, tielayer, polyketone, respectively.

The polyketone was processed at a melt temperature between 240 °C and 260 °C. The amine modified carboxylic acid copolymer (as a tielayer) was processed through the 25 mm extruder at 160 °C. The high density polyethene was processed at a melt temperature of 200-210 °C. The three streams were processed through the die head at 260 °C.

A T-peel test was then conducted on the co-extruded tubing. In this test, the tubing was sliced open longitudinally. The two main layers were separated on one end slightly by hand to produce two end tabs capable of being placed in an tensile tester. A tensile tester was then used to determine the stress necessary to completely separate the layers at 90° to one another.

The test was carried out at 23 °C with a cross-head speed

of 127 mm/min. The T-peel adhesion is reported in units of force per unit width of the specimen.

Failure of the material under consideration was characterized as cohesive or adhesive by observation during the T-peel test. Cohesive failure occurs when the tielayer matrix itself is yielded and/or torn upon application of sufficient force. It indicates good interfacial adhesion between the tielayer (s) and the other polymers to which it is bound. Adhesive failure occurs when the tielayer simply separates from one or more other polymer layers to which it is bound during the course of the test. It indicates that the interfacial bond between tielayer and other polymer layers is lower than the overall tensile strength of the tielayer.

Viscosity rise of the amine modified carboxylic acid copolymers was measured using a capillary rheometer heated to 240 °C. The sample was introduced and the apparent viscosities determined at a shear rate of 100 s-1. The percent viscosity rise was determined by comparing the viscosity at 25 minutes (unless otherwise indicated) to that at 3 minutes. A high rate of viscosity rise indicates a rapid rate of cross-linking.

Results are provided in the following Table.

Table Ex. AcidAmineAdhesionType% No. copolymer (wt%,plyfailureViscosity (melt on acid (N/mm) rise at flow, copolymer) 240 °C, g/10 min) 25 min 2* 1 (3) A (0.25 %) 7. 6 Cohesive 100 (10 min) 3* 1 (3) B (0.5 %) 2. 9 Adhesive 69 4 2 (7) B (0.5 %) 1. 5 Adhesive 9 5 2 (7) A (0.25 %) 3. 0 Adhesive 25 6 2 (7) A (0.5 %) 3. 0 Cohesive 38 7 3 (3) A (0.25 %) 5. 1 Adhesive 28 8 3 (3) A (0.5 %) 6. 8 Cohesive 40 9* 4 (11) A (0.25 %)tt900 (15 min) * Comparative, not according to the invention. t Not determined.

Comparing Examples 2 and 3 with Examples 4-8, in particular Example 2 with Example 7 and Example 3 with Example 8, it can be seen that while the composites made with high carboxylic acid content amine modified hindered carboxylic acid copolymers can display good adhesion, their melt stability is substantially less than that of the materials made according to the invention. That is, they tend to cross-link in the melt. Example 9 shows less stability in the melt when an unhindered carboxylic acid is used in the tielayer.

A comparison of Example 7 with Example 5 and of Example 8 with Example 6 shows that the use of a hindered carboxylic acid copolymer with lower melt flow leads to better bonding between layers. A comparison of Example 6 with Example 4 shows that the use of an unhindered amine leads to better bonding between layers.