WO2000009330A1

WO2000009330A1 - Multi-layered structures

Info

Publication number: WO2000009330A1
Application number: PCT/GB1999/002657
Authority: WO
Inventors: James Graham Bonner; Alan Gray
Original assignee: Bp Chemicals Limited
Priority date: 1998-08-14
Filing date: 1999-08-11
Publication date: 2000-02-24
Also published as: AU5380099A; GB9817609D0

Abstract

A multi-layered structure comprising a polyolefin layer and a polyketone layer bonded together with an adhesive composition comprising an amine-functionalised polyolefin. The amine functionalised polyolefin is a copolymer having units derived from a nitrogen-containing olefinic monomer, and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene and is obtainable by masked polymerisation.

Description

MULTI LAYERED STRUCTURES

The present invention relates to adhesive compositions and multi-layered structures comprising the adhesive compositions, in particular, multi-layered structures comprising at least one layer of a polyketone composition.

For the purposes of this patent, polyketones are defined as linear polymers having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefmically unsaturated compounds. Although for the purposes of this patent polyketones correspond to this idealised structure, it is envisaged that materials corresponding to this structure in the main but containing small regimes (i.e. up to 10wt%) of the corresponding homopolymer or copolymer derived from the olefmically unsaturated compound, also fall within the definition. Such polyketones have the formula:

where the R¹, R², R³ and R⁴ groups are independently hydrogen or hydrocarbyl groups, and m is a large integer; they are disclosed in several patents e.g. US 3694412.

Processes for preparing the polyketones are disclosed in US 3694412 and also in EP 181014 and EP 121965.

Adhesive compositions, also known as tie-layers or melt adhesives, are employed to bind together layers of materials which otherwise do not stick together satisfactorily.

Polyolefin-containing blends suitable for use as adhesive layers in multi-layered structures are known. These adhesive blends are commonly referred to as tie-layers. For example, US Patent 2081723 discloses a modified polyolefin adhesive blend comprising

(A) a graft copolymer of a polyethylene back-bone grafted with at least one polymerisable ethylenically unsaturated carboxylic acid or carboxylic acid anhydride and

(B) a blending resin mixture comprising a linear low density polyethylene and polypropylene. The patent states that the adhesive blends can be used to join polypropylene to a number of polar materials or to join two polar materials together.

WO 9509212 relates to a polyolefin-containing adhesive blend suitable for bonding polyolefins, in particular, polyethylene or polypropylene to polyketones which blend has good adhesion to polyolefins while maintaining good adhesion to the polyketone. The polyolefin-containing adhesive blend is said to comprise:

(A) 1 to 30 parts by weight of a graft copolymer having a polyolefin backbone grafted with 0.001 to 30% by weight of at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof,

(B) 70 to 99 parts by weight of a polyolefin provided that at least 5 parts by weight of(B) is

(C) a polyolefin having a density of less than 930kgm^"3 wherein the graft copolymer (A) has been reacted with a compound (D) which has at least two primary or secondary amino groups at least one of which is a primary amino group, the sum of (A), (B) and (C) being 100 parts by weight. There remains the need for further adhesive compositions which have good adhesion to both polyolefins and polyketones.

US 5,030,370 relates to a composition comprising (A) lubricating oil, and (B) at least one amino-substituted interpolymer (e.g. an ethylene alpha-olefin interpolymer) substituted by primary amino or secondary amino groups useful as a viscosity index improver dispersant. Such amino-substituted interpolymers can be prepared by co- polymerising ethylene (and, optionally, an alpha-olefin) with a masked nitrogen- containing monomer wherein the primary or secondary nitrogen group of the nitrogen- containing monomer is masked with an organometallic compound followed by demasking the resulting interpolymer to remove the organometallic compound and thereby form the amino-substituted interpolymer. Preferred amino-substituted interpolymers comprise amino-substituted ethylene propylene norbornene terpolymers. However, there is no suggestion in US 5,030,370 that the amino-substituted interpolymers (B) would be suitable for use as tie-layers for adhesion of polyolefins to polyketones.

According to the present invention there is provided a multi-layered structure comprising a first layer comprising a polyolefin composition and a second layer comprising a polyketone composition, the first and second layers being bonded together with an intermediate layer of an adhesive composition comprising an amine- functionalised polyolefin wherein the amine functionalised polyolefin is a copolymer having units derived from a nitrogen-containing olefinic monomer (NCM), and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha- olefin and a non-conjugated diene.

The polyolefin composition of the first layer may comprise a polyolefin, blends of polyolefins or blends of a polyolefin and a polymer other than a polyolefin (for example, a blend of a polyolefin and a polyamide). Preferably, the polyolefin composition of the first layer comprises a major proportion of an olefin homopolymer, copolymer or terpolymer. The polyolefin composition of the first layer may comprise a recycled polyolefin or a mixture of recycled and virgin polyolefin. The polyolefin composition of the first layer may contain conventional fillers. Suitable polyolefins include a homopolymer of an olefin e.g. ethylene or propylene, in particular polypropylene, a high density polyethylene (HDPE), a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE) or a very low density polyethylene (VLDPE), preferably polypropylene, HDPE or LLDPE. Alternatively, the polyolefin may be a copolymer of an olefin e.g. propylene with ethylene, butylene or other unsaturated aliphatic hydrocarbons or a terpolymer of an olefin e.g. ethylene with propylene and a diene. The polyketone composition of the second layer comprises a linear polymer having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefmically unsaturated compounds. Suitable olefinic units are those derived from C to C_]2 alpha-olefins or substituted derivatives thereof or styrene or alkyl substituted derivatives of styrene. It is preferred that such olefin or olefins are selected from C₂ to Cβ normal alpha-olefins (i.e. straight chain alpha-olefins) and it is particularly preferred that the olefin units are either derived from ethylene or most preferred of all from a mixture of ethylene and one or more C₃ to Cβ normal alpha- olefin(s) especially propylene or butylene (i.e. an ethylene/propylene/CO terpolymer or an ethylene/butylene/CO terpolymer). In these most preferable materials it is further preferred that the molar ratio of ethylene units to C₃ to Cβ normal alpha-olefin units is greater than or equal to 1 most preferably between 2 and 30. The polyketone composition of the second layer may comprise blends of polyketones or blends of polyketones and a polymer other than a polyketone (for example, polystyrene, polyamides, HDPE, LLDPE, LDPE or polypropylene).

The polyketones employed in the invention preferably have a number average molecular weight of from 20000 to 500,000, preferably from 30,000 to 300,000, more preferably from 40,000 to 200,000 as determined by gel permeation chromatography. The melting point of the polyketones is preferably between 175 and 260°C, preferably from 180 to 250°C.

Where the amine-functionalised polyolefin of the adhesive composition has units derived from an alpha-olefin, a C to C₂₅ alpha-olefin is preferred. The alpha-olefin may be branched or straight chained, cyclic, aromatic substituted or unsubstituted, and is preferably a C₃ to Ci6 alpha-olefin. Mixed alpha olefins can be used (e.g. mixed butenes).

The alpha-olefin, when substituted, should not be aromatic substituted on the 2- position (e.g. moieties such as CH₂=CH-Φ- should not be employed), since such an aromatic group interferes with the subsequent desired polymerisation reaction.

Examples of suitable substituted alpha-olefins are disclosed in US 5,030,370 which is herein incorporated by reference. Illustrative examples of preferred alpha-olefins are propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-dodecene.

Where an alpha olefin is incorporated into the amine-functionalised polyolefin, the alpha olefin is generally incorporated in an amount of between 10 and 90 wt%, more preferably 20 to 70 wt% based on the total weight of the amine-functionalised polyolefin.

Where the amine-functionalised polyolefin has units derived from a non- conjugated diene, a Cβ to C₁5 non-conjugated diene is preferred. Preferably, the non- conjugated diene is a straight chain hydrocarbon di-olefin or a cycloalkenyl-substituted alkene, for example:

A. a straight chain acyclic diene,

B. a branched chain acyclic diene, C. a single ring alicyclic diene, and

D. a multi-ring alicyclic fused or ridged ring diene.

Examples of such dienes are given in US 5,030,370. Of the non-conjugated dienes typically used, the preferred dienes are dicyclopentadiene, 1,4-hexadiene, 5- methyl-2-norbornene, and 5-ethylidene-2-norbornene.

Where a non-conjugated diene is incorporated into the amine-functionalised polyolefin, the non-conjugated diene is generally incorporated in an amount of from 0.5 to 15 wt%, preferably from 1 to 10 wt%, for example, 5 wt% based on the total weight of the amine-functionalised polyolefin. The amine-functionalised polyolefin of the adhesive composition is obtainable by:

(A) copolymerising (a) a masked nitrogen-containing olefinic monomer and (b) an olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene; and (B) demasking the resulting copolymer to form the amine-functionalised polyolefin.

The nitrogen-containing olefinic monomer (NCM), which is masked prior to the polymerisation, is suitably an unsaturated, nitrogen-containing olefinic monomer having the general formula:

R'(X)„ wherein R¹ is selected from ethylenically unsaturated hydrocarbyl radicals, and X is selected from the group consisting of amino (-N(H)R') groups, imino groups (-CH=N- R'), and cyano (-C≡N) moieties, and wherein n is an integer of at least 1, preferably 1-4, and more preferably 1-2. R' in the above groups may comprise H or a hydrocarbyl (preferably H or saturated hydrocarbyl), for example, a saturated hydrocarbyl having 1 to 15 carbon atoms, and preferably an alkyl having 1 to 5 carbon atoms or a cycloalkyl having from 3 to 7 carbon atoms. Exemplary amino groups include -NH₂ and alkyl amino groups, for example, -NHCH₃, NHC₂H₅, -NHC₃H₇ and -NHC₄H₉.

The unsaturation in R¹ is such that it is easily polymerised, for example, using a Ziegler catalyst. R¹ preferably contains from 2 to 25 carbon atoms, and preferably from 2 to 16 carbon atoms. In particular, R¹ is selected from the group consisting of radicals derived from ethylene, alpha-olefins, and norbornenes, or from the group consisting of vinyl and allyl radicals. Representative examples of such unsaturation are provided in US 5,030,370.

The NCM is preferably soluble in the liquid hydrocarbon solvent or diluent selected for use in the subsequent polymerisation reaction (e.g. saturated hydrocarbon solvents, such as hexene). Suitable nitrogen-containing olefinic monomers include norbornenyl-methyl amines and imines (such as 5-norbornene-2-methylamine, 5-norbornene-2,3- dimethyl amine, 5-norbornene-2-ethylamine, and 5-norbornene-2-(4'-butenyl)imine) and norbornenyl-nitriles (such as 5-norbornene-2-nitrile, and 5-norbornene-2,3-dinitrile).

The NCM may also include multiple functionality, that is the R¹ moiety may be substituted by more than one "X" group, in which case the functional groups "X" may be the same or different.

The nitrogen-containing monomers may be prepared by conventional methods. Agents which are effective in masking the nitrogen-containing olefinic monomers include metal alkyls and metal alkyl hydrides and are described in detail in US 5,030,370.

The term masked, nitrogen-containing olefinic monomer (MNCM) is intended to refer to the reaction products formed by the reaction of the nitrogen-containing olefinic monomer and a masking agent comprising at least one metallic organic compound. The MNCM so formed is used as the actual comonomer in the polymerisation process. Preferred masked nitrogen-containing olefinic monomers useful for the preparation of the amine-functionalised polyolefin are disclosed in US 5,030,370. The masking reaction provides a chemical deactivation of the reactivity of the nitrogen-containing olefinic monomer otherwise the unmasked nitrogen-containing functionality would tend to react almost immediately with the catalyst under the polymerisation conditions thereby leading to a loss of activity.

The masking reaction, which can be performed in a batchwise, continuous or semi-continuous manner, is preferably carried out by adding the NCM to the selected metal alkyl masking agent, preferably in the presence of an inert solvent or diluent. Suitable reaction conditions for the masking reaction are disclosed in US 5,030,370. The copolymerisation of (a) the MNCM and (b) the olefinic monomer(s) may be performed in an otherwise conventional manner using suitable methods, including batchwise, semi-batch or continuous operations in the presence of catalysts known to be effective for conventional polymerisation of olefinic monomers. Suitable catalysts and polymerisation reaction conditions are described in US 5,030,370.

After polymerisation, the polymerisation is quenched in a conventional manner (see US 5,030,370). The desired amino functional group, i.e., X, incorporated into the amine- functionalised polyolefin as the masked functional group, can be regenerated by removal of the masking metal, M, through the use of conventional demasking techniques, wherein the quenched polymerisation product, containing masked-functionalised polyolefin, the polymerisation catalyst, and unreacted monomers, is contacted with an aqueous liquid, e.g. water, aqueous solutions containing mineral acids, aqueous solutions containing mineral bases or mixtures thereof. The resulting hydrolysis reactions liberate the metal masking agent and generate the amine-functionalised polyolefin. Details of the hydrolysis reactions and methods of recovering other amine-functionalised polyolefin are given in US 5,030,370. Examples of amine-functionalised polyolefins for use in the adhesive composition of the present invention include functionalised polypropylenes (propylene homopolymers, propylene-ethylene copolymers containing less than 10 wt % ethylene, propylene-higher olefin copolymers containing up to 10 wt% of higher alpha-olefins such as hexene-1, penten-1, and octene-1), functionalised polyethylenes (ethylene homopolymers and ethylene-propylene copolymers containing greater than 90 wt% ethylene) ethylene-propylene copolymers (e.g. elastomeric EPM), ethylene-propylene- diene terpolymers (e.g. elastomeric EPDM).

The NCM may be present in the amine-functionalised polyolefin in an amount of from 0.01 to 40 wt%, based on the total weight of the amine-functionalised polyolefin, preferably 0.1 to 20 wt%, more preferably 0.75 to 10 wt%, and most preferably 1 to 7 wt % The preferred amine-functionalised ethylene-propylene copolymer employed in this invention may comprise from 20 to 90 wt% ethylene, 10 to 80 % propylene and 0.01 to 40 % nitrogen-containing olefinic monomer. The preferred amine-functionalised ethylene-propylene-diene terpolymer employed in this invention may comprise from 20 to 90 wt % ethylene, from 10-80 wt% propylene, from 0.5 to 15 wt% non-conjugated diene and from 0.01 to 40 wt% nitrogen-containing olefinic monomer.

The amine-functionalised polyolefins employed in this invention have a number average molecular weight in the range 10,000 to 500,000, preferably 10,000 to 200,000, more preferably 20,000 to 150,000.

Preferably, the amine-functionalised polyolefin will have within its structure, on average, at least 0.5 (e.g. from 0.5 to 20), and preferably at least 1 pendent reactive amine group (i.e. primary and/or secondary amine groups) per polymer molecule. Preferably, the amine-functionalised polyolefins have a substantially homogeneous distribution of amine functionality between the polymer chains. The distribution of the amine groups is discussed in detail in US 5,030,370.

The adhesive composition may comprise blends of two or more of the amine- functionalised polyolefin polymers.

Optionally, a polyolefin is added to the adhesive composition to modify the rheological, viscoelastic or adhesive properties of the composition (hereinafter referred to as "modifying polyolefin"). Any suitable polyolefin can be used as the modifying polyolefin e.g. polyethylene, polypropylene, copolymers of ethylene or copolymers of propylene with one or more comonomers e.g. butene. Suitably, the modifying polyolefin may be a very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE) or ethylene propylene rubbers. A mixture of two or more modifying polyolefins can be added to the adhesive composition of the present invention, preferably two polyolefins e.g. a polypropylene and a VLDPE. Thus, according to a further embodiment of the present invention there is provided an adhesive composition comprising:

(a) an amine-functionalised polyolefin having units derived from a nitrogen-containing olefinic monomer, and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene; and (b) a modifying polyolefin.

Where a modifying polyolefin is added to the adhesive composition, the modifying polyolefin is present in amounts of from 5 to 95% by weight, preferably 5 to 25%> by weight based on the total amount of the composition.

The adhesive composition may optionally comprise a polyketone. Where a polyketone is present in the adhesive composition it is preferred that the polyketone is present in the adhesive composition in amounts in the range 10 to 50%ι by weight, more preferably 20 to 40% by weight based on the total weight of the polymers of the adhesive composition.

The copolymer, the optional modifying polyolefin and the optional polyketone of adhesive composition can be blended using known techniques and equipment for batch or continuous blending. The adhesive composition may also contain conventional additives such as, for example, antioxidants, stabilisers, and mould release agents.

Methods for using adhesive compositions to bond polyolefins to polar substrates (to form multi-layered structures) are known and include lamination, coextrusion, extrusion lamination and coextrusion coating. The multi-layered structures according to the present invention can include further layers in addition to the three layers hereinbefore defined. For example, a five- layered structure can comprise a first layer of a polyolefin composition, a second layer of an adhesive composition as defined above, a third layer of a polyketone composition, a fourth layer of an adhesive composition as defined above and a fifth layer of a polyolefin composition.

It has been found that the use of the adhesive composition as defined above to produce multi-layered film or sheet provides a satisfactory bond when the film or sheet is subsequently thermoformed, i.e. the film or sheet does not have a tendency to delaminate after thermoforming, into articles e.g. receptacles (such bottles, cups, bowls and trays), pipes and tubing. The present invention includes articles produced by thermoforming a multi-layered film or sheet comprising a first layer comprising a polyolefin composition and a second layer comprising a polyketone composition, the first layer and the second layer being bonded together by an intermediate layer of an adhesive composition comprising an amine-functionalised polyolefin as defined above. The present invention also relates to multi-layered articles produced by coextrusion blow moulding as well as to multi-layered pipes and tubing produced by coextrusion.

The invention is illustrated by the following example: Materials

The polyketone (PK) employed in the adhesive tests was an ethylene/propylene/CO terpolymer having a melting point of 210°C and a melt flow rate (MFR) of 9 g/10 minutes (240°C, 5kg load).

The polyethylene (PE) employed in Example 2 was PC002-40, ex BP Chemicals and is suitable for use in pipe applications.

The polypropylene (PP) employed in Example 3 was Acctuf 3234X, ex Amoco and is suitable for use in injection moulding applications.

The amine-functionalised polyolefin employed in the adhesive test was Paratone 8950 (Trade Mark) which was supplied by Exxon Chemical in pellet form. Paratone 8950 has a melt flow rate of 3.1 g/10 minutes (190°C, 2.16 kg load).

The polyketone was compounded with 1% pseudoboehmite and 0.1% Irganox 1010 and was then was formed into pellets. The compounding was conducted using a Prism 16mm corotating twin screw extruder. The temperature profile across the feed, barrel and die sections of the extruder was 200, 215 and 225°C respectively. A screw speed of 200 rpm and a torque of 40-50% were used. Determination of Melt Flow Rate

The melt flow rate (MFR) of the polyketone was measured using a Davenport Melt Index Tester. Tests were carried out at a temperature of 240°C using an applied load of 5 kg. The MFR was calculated from the mass of extrudate pushed through a die (2.095 mm diameter) over a 30 second period on application of the load 4 minutes after charging the polymer into the barrel of the instrument at a temperature of 240°C. Otherwise, standard MFR procedures were followed (e.g. ISO 1133).

The melt flow rate of the amine-functionalised polyolefin was determined using the above procedure except that the tests were carried out at a temperature of 190°C using an applied load of 2.16 kg. Example 1 Film preparation

Pellets of the polyketone were extruded into a film having a thickness of approximately 130μm. Similarly, pellets of the amine-functionalised polyolefin were extruded into a film having a thickness of 130μm. The extrusion was performed using a Plasticisers 22mm single screw extruder with a temperature profile from the feed section to the die of 180, 200, 210, and 220°C, and a screw speed of 30 rpm. The extruder was equipped with a die (0.38 x 64 mm) and an air gap of 10 mm between the die and the take-off roll. Adhesion test

A multi-layered structure (polyketone/amine-functionalised polyolefin/polyketone) was prepared using a 20 tonne Moore press via the following procedure:

Three individual films (PK/amine-functionalised polyolefin/PK), prepared as described above, were placed in a 15cm x 15cm x 0.39mm "picture frame" mould. This was preheated using a press platen temperature of 260°C for 30 seconds under contact pressure, before being pressed for 10 seconds at a pressure of 10 tonnes. The mould was then crash cooled to room temperature. The resultant multi-layer structure was cut into 2.5 cm wide strips and the level of adhesion between the layers was assessed using a standard T-peel test (in accordance with BS 5350). Although the layers could be separated, cohesive failure occurred which indicates that there is a high level of adhesion between the polyketone layers and the amine-functionalised polyolefin layer. Example 2

Sheets of the polyethylene(PE) and the amine-functionalised polyolefin were prepared by compression moulding using a 60 x 60 x 0.15 mm "picture frame mould" and aluminium backing plates in a Moore Press under the following conditions: 180- 190°C for 2 minutes under contact pressure, 180-190°C for 2 minutes at 15 tonnes pressure, and cooling at 15°C/minute to ambient temperature under full pressure. It was found that it was easier to separate the sheet of the amine-functionalised polyolefin from the aluminium backing plates by cooling to a temperature of approximately 70°C and removing the sheet under running cold water. The polyketone (PK) layer was prepared as in Example 1. The individual component layers (PE/amine-functionalised polyolefin/PK) were compression moulded in a "picture frame" mould in a similar manner to compression moulding the individual PE and amine-functionalised polyolefin sheets except that the temperature used was 260°C. The resulting multi-layered structure had dimensions of approximately 60 x 60 x 0.43 mm. The extent of adhesion was evaluated manually by peeling the layers. The PE/amine-functionalised polyolefin interface could be separated but there was a strong bond exhibiting cohesive failure. The PK/amine-functionalised polyolefin could not be separated. Example 3 Example 2 was repeated except that the polyethylene (PE) was replaced by polypropylene (PP).

The PP/amine-functionalised polyolefin interface could be separated but there was a strong bond exhibiting cohesive failure. The PK/amine-functionalised polyoelfin could not be separated.

Claims

Claims:

1. A multi-layered structure comprising a first layer comprising a polyolefin composition and a second layer comprising a polyketone composition, the first and second layers being bonded together with an intermediate layer of an adhesive composition comprising an amine-functionalised polyolefin wherein the amine functionalised polyolefin is a copolymer having units derived from a nitrogen-containing olefinic monomer, and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene.

2. A multi-layered structure as claimed in claim 1 wherein the polyketone composition of the second layer comprises a linear polyketone polymer having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefmically unsaturated compounds.

3. A multi-layered structure as claimed in claim 2 wherein the polyketone composition of the second layer comprises an ethylene/propylene/CO terpolymer or an ethylene/butylene/CO terpolymer.

4. A multi-layered structure as claimed in any one of the preceding claims wherein the amine-functionalised polyolefin has units derived from a C₃ to Ciβ alpha-olefin.

5. A multi-layered structure as claimed in claim 4 wherein the units derived from the alpha-olefin are incorporated in the amine-functionalised polyolefin in an amount of between 10 to 90 wt% based on the total weight of the amine-functionalised polyolefin.

6. A multi-layered structure as claimed in any one of the preceding claims wherein the amine-functionalised polyolefin has units derived from a Cβ to C15 non-conjugated diene.

7. A multi-layered structure as claimed in any one of the preceding claims wherein the units derived from the non-conjugated diene are incorporated in the amine- functionalised polyolefin in an amount of from 0.5 to 15 wt% based on the total weight of the amine-functionalised polyolefin.

8. A multi-layered structure as claimed in any one of the preceding claims wherein the amine-functionalised polyolefin has units derived from an unsaturated, nitrogen- containing olefinic monomer having the general formula:

R^L(X)„ where R¹ is selected from ethylenically unsaturated hydrocarbyl radicals, X is selected from the group consisting of amino (-N(H)R') groups, imino groups (-CH=N-R'), and cyano (-C≡N) moieties, n is an integer of at least 1, and R' is H or a hydrocarbyl.

9. A multi-layered structure as claimed in claim 8 wherein R' is selected from the group consisting of H, an alkyl having 1 to 5 carbon atoms and a cycloalkyl having from 3 to 7 carbon atoms.

10. A multi-layered structure as claimed in claims 8 or 9 wherein R¹ contains from 2 to 25 carbon atoms.

11. A multi-layered structure as claimed in any one of the preceding claims wherein the units derived from the nitrogen-containing olefinic monomer are incorporated in the amine-functionalised polyolefin in an amount of from 0.01 to 40 wt%> based on the total weight of the amine-functionalised polyolefin.

12. A multi-layered structure as claimed in any one of the preceding claims wherein the amine-functionalised polyolefin has within its structure from 0.5 to 20 pendent reactive amine groups per polymer molecule.

13. A multi-layered structure as claimed in any one of the preceding claims wherein the amine-functionalised polyolefin of the adhesive composition is obtainable by: (A) copolymerising a masked nitrogen-containing olefinic monomer and an olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non- conjugated diene; and (B) demasking the resulting copolymer to form the amine-functionalised polyolefin.

14. An adhesive composition comprising:

(a); an amine-functionalised polyolefin having units derived from a nitrogen-containing olefinic monomer, and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene; and (b) a modifying polyolefin.

15. An adhesive composition as claimed in claim 14 wherein the modifying polyolefin is selected from the group consisting of a very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE) and ethylene propylene rubbers.

16. An adhesive composition as claimed in claims 14 or 15 wherein the modifying polyolefin is added to the adhesive composition in an amount of from 5 to 25% by weight, based on the total amount of the composition.

17. Use of an adhesive composition comprising an amine-functionalised polyolefin wherein the amine functionalised polyolefin is a copolymer having units derived from a nitrogen-containing olefinic monomer, and at least one further olefinic monomer selected from the group consisting of ethylene, an alpha-olefin and a non-conjugated diene to bond a layer of a polyolefin composition to a layer of a polyketone composition.