Adhesive polymer materials

Abstract

A laminar structure comprising a substrate bonded to a coating wherein the bonding is provided by an intermediate layer of a block copolymer of structure (I) and the intermediate layer preferably comprises a thermoplastic film coated with the block copolymer which is also of the invention.

Description

[0001] PAINT2242 WO - 24 Sep 2025

[0002] ADHESIVE POLYMER MATERIALS

[0003] In our PCT International Publication Number WO2023 / 161238 we describe polymers having improved adhesive properties and in particular which have improved adhesion to olefin polymer substrates such as polyethylene and polypropylene and copolymers of ethylene and propylene with other olefinic monomers. The polymers are also said to improve the adhesion of coatings such as paints, inks, adhesives, sealants, varnishes and primers to olefin polymers and copolymers.

[0004] According to WO2023 / 161238 the polymers that provide the adhesive properties may be included in the substrate or applied to the surface of the substrate as a coating comprising a solution or dispersion of the polymer.

[0005] We have now found that if a certain amount of certain block copolymers is provided on a substrate as a coated film at a certain thickness the film provided can be used as an interlayer to provide adhesion of coating materials to substrates to provide a strong bond of the coating material to the substrate, particularly a bond whose cohesive strength is greater than the strength within the coating.

[0006] In the present application the following terms have the following meaning.

[0007] A film is the base material in or on which the block copolymer is provided.

[0008] A coating is a layer of the block copolymer that is applied to one or both surfaces of the film.

[0009] A coating material is the material that is applied to the coating or the film and is to be bonded to the substrate.

[0010] A substrate is a material to which the coating material is to be adhered by means of a film.

[0011] In one embodiment this invention provides a coated film of thickness from 400 pm preferably 20 pm to 300 pm, more preferably 20 pm to 200 pm comprising a polyolefine and which provides from 0.1 % to 30%, preferably 0.1 to 10% of the combined weight of the coated film and the block copolymer of a block copolymer of the following structure. PAINT2242 WO - 24 Sep 2025 where R and R1may be the same or different and each independently represents an alkyl or aryl group, X may be hydrogen or a C1 to C20 alkyl group which may be branched or linear and wherein the aromatic ring substituent joined to Polymer B is positioned meta or para to the aromatic ring substituent joined to Polymer A, characterized in that: a) Polymer A is a polymer or copolymer of an olefine and b) Polymer B is a polymer of a polar monomer comprising one or more of a,p- unsaturated monomers selected from the group consisting of carboxylic acids, styrene, substituted styrene, acrylate, methacrylate, vinyl esters, fumarate esters and maleic anhydride and derivatives thereof, and diene compounds.

[0012] The block copolymer may be provided as an additive within the film or preferably is provided as a coating on one or both surfaces of the film.

[0013] In an embodiment the invention provides a substrate preferably a polyolefine substrate bonded to a film comprising the coating containing the block copolymer of the invention.

[0014] In a further embodiment the invention provides the use of a coating to provide adhesion between a polyolefine substrate and a coating material.

[0015] In yet a further embodiment the invention provides a process for the production of a coated substrate comprising laying up a coated film according to this invention on the surface of a substrate and optionally applying pressure at a temperature in the range of 110°C to 240°C, preferably 110 °C to 230 °C to bond the coated film to the substrate and subsequently applying a coating material on the exposed surface of the coating. The coating material may also be bonded to the coating and thus to the substrate by applying pressure typically at a temperature in the range of 110 °C to 130 °C. PAINT2242 WO - 24 Sep 2025

[0016] In a further embodiment the invention provides a laminar structure comprising a substrate and a coating material including an intermediate layer comprising a film according to this invention.

[0017] In a further embodiment the invention provides a process for the production of a coated substrate comprising laying up a coated film on the surface of a substrate and providing a coating material on the exposed surface of the coated film and applying pressure at a temperature in the range of 110 °C to 230 °C to bond the coating material to the coated film.

[0018] The coating containing the block copolymer may be applied as a film containing or carrying the block copolymer for example a polyolefin film containing from 5 to 30 wt %, preferably 5 to 20 wt % of the block copolymer. The block copolymer may be incorporated in the film or it may be provided on the surface of the film. The coating may be applied as a solution or dispersion of the block copolymer in a liquid carrier which can be removed after application of the coating to leave the block copolymer as a coating on the substrate. The solution or dispersion may contain other polymers in addition to the block copolymer.

[0019] When the coating is applied as a solution or dispersion it preferably contains from 10 to 30 wt % preferably 15 to 25 wt % of solids, the remainder comprising a solvent or liquid dispersing medium, of the solids the diblock copolymer preferably comprises 2 to 20 wt % preferably 5 to 15 wt %; from 0 to 20 wt % of an additional polymer or copolymer which may be a mixture of a polar polymer or copolymer and a polyolefin such as polypropylene. The coating may be applied by a suitable coating technique such as gravure coating it may be applied to a supporting film such as a polypropylene film which is particularly useful to promote adhesion between a polypropylene substrate and a coating material. The adhesive coating promotes the adhesion of coating materials such as inks, paints and other adhesives required on the substrate. The polypropylene film may be fibre reinforced such as with carbon fibre, glass fibre or aramid fibre. Although polypropylene is preferred other polyolefines such as various polyethylenes (high density or low density) may be used as may olefin copolymers. The film may be of any suitable thickness, a preferred thickness from 30 to 300 pm, preferably 50 pm to 100 pm.

[0020] In further embodiments the film and optionally the coating material may be applied to both surfaces of a substrate.

[0021] In a preferred embodiment PAINT2242 WO - 24 Sep 2025 i) polymer A comprises a chain of ethylenic or propylenic structural units, optionally copolymerised with higher 1 -alkene co-monomers, preferred chains are polyethylene or polypropylene or propylene / ethylene copolymer chains and ii) polymer B is derived from two or more a,p - unsaturated polar monomers selected from styrene, substituted styrene, unsaturated esters such as acrylate, methacrylate esters such as butyl acrylate, methyl(meth) acrylate, 2-ethyl hexyl methacrylate, glycidyl methacrylate, poly(ethylene glycol) methacrylate, butyl methacrylate, and hydroxyethyl acrylate and vinyl esters, fumarate esters, itaconate esters, maleic anhydride, unsaturated acids such as acrylic acid and methacrylic acid ionomers and diene compounds and derivatives thereof, polymer B may comprise a copolymer of such unsaturated monomers with an alkene such as a C2 to Cs, preferably a C2 to Ce alkene; styrene is considered to be a polar monomer as it has a dipole moment and can be polymerised with a free radical catalyst.

[0022] The block copolymer used in this invention may be prepared by a) in a first step, polymerising alkenes such as ethylene, propylene or mixtures thereof and optionally one or more 1 -higher alkene co-monomers, to form polymer A, being a chain consisting of ethylenic, propylenic or ethylenic / propylenic structural units optionally bearing pendent alkyl groups originating from 1 -alkene comonomer(s), the polymerisation reaction being carried out in the presence of a compound of the formula

[0023] (I): wherein, in the course of the reaction, the compound (I) is terminally incorporated onto polymer A resulting in the formation of a terminally unsaturated intermediate of the formula (II): PAINT2242 WO - 24 Sep 2025 b) in an optional second step, recovering the intermediate (II) from the reaction mixture of the first step; and c) in a third step, reacting the intermediate (II) at its terminal double bond with one or more polar monomers (optionally copolymerized with a non-polar monomer) in a subsequent polymerisation reaction to form polymer B attached to intermediate (II). where R, R1 and X are as previously defined.

[0024] Optionally step a) may be performed under hydrogen pressure in order to control the characteristics of polymer A. Step a) employs a catalyst for the polymerisation of the monomer and also the reaction of the polymer with the compound of the formula (I). Any suitable olefine polymerisation catalyst may be used such as traditional Ziegler catalysts, metallocene catalysts being preferred although catalysts referred to in Angie-Chem. Int. Ed 2014 2-25 entitled Post Metallocenes in the Industrial Production of Polyolefins may be used.

[0025] In this specification, the word “terminal” when used in relation to a polymer chain (or block) simply refers to the end of the polymer chain (or block), and does not convey any additional mechanistic requirement that the chain (or block) end in question be the end at which the polymerisation reaction terminated. References to “terminally” shall be construed analogously.

[0026] The mechanism by which the adhesion of the coating material to the substrate is improved is believed to be that polymer A of the block copolymer adheres to the polymer of the film which in turn adheres to the polymer of the substrate. Polymer B on the other hand adheres to the coating material due to the interaction of the polarity of polymer B and the polarity of the coating material. Accordingly, it is important that in the block copolymer polymer A be terminally joined to polymer B, so as to leave polymer B exposed for interacting with the coating material which is to be adhered to the substrate. As such, it is important that the linkage between polymer A and polymer B be positioned at the end of the polymeric chain of polymer A. PAINT2242 WO - 24 Sep 2025

[0027] To achieve this terminal positioning of the linkage between polymer A and polymer B, it is essential that the process by which the copolymer is made be specific for terminal functionalization of polymer A. Equally, it is important that the terminal functionalization formed on polymer A be sufficiently reactive to enable the subsequent formation of polymer B typically under radical polymerisation conditions that are industrially practical, whilst at the same time not being so highly reactive that unwanted side reactions occur to a significant extent.

[0028] Preferred block copolymer materials for use in this invention are those in which polymer A comprises a chain of ethylenic or propylenic structures or an ethylene / propylene copolymer chain optionally interrupted by one or more structural units derived from higher 1 -alkene comonomers such as hexene or octene and polymer B comprises a chain of structural units derived from two or more a,p - unsaturated polar monomers selected from unsaturated carboxylic acids, styrene, substituted styrene, unsaturated esters such as acrylate and methacrylate esters, vinyl esters, fumarate esters, itaconate esters, maleic anhydride, unsaturated acids such as acrylic acid and methacrylic acid and diene compounds and derivatives thereof, polymer B may be a copolymer of such monomers with an alkene such as a C2 to C8 alkene. In a preferred embodiment polymer B is a copolymer of at least three monomers with at least some of the monomers providing pendant polar groups on polymer B for interaction with the polar groups in the coating material. Styrene is considered to be a polar monomer in that it can be polymerised by free radical catalysis and has a dipole moment.

[0029] Preferably, each R and R1group independently represents an alkyl group having from 1 to 4 carbon atoms. More preferably, R and R1are the same and most preferably are both methyl.

[0030] Preferably, the aromatic ring substituent joined to polymer B is positioned meta to the aromatic ring substituent joined to polymer A.

[0031] Polymer A therefore is selected to be compatible with the olefine polymer or copolymer that forms the substrate to which the coating material is to be adhered. We prefer that when the block copolymer is to be used with a predominantly polypropylene based substrate polymer A is predominantly comprised of propylene although other comonomers can also be present. Similarly, when the block polymer is to be used with a predominantly polyethylene based substrate polymer A is preferably predominantly comprised of polyethylene although hereagain other comonomers can also be present. We have generally found that this leads to improved adhesion between the coating material and the substrate. PAINT2242 WO - 24 Sep 2025

[0032] In another preferred embodiment, polymer A in the block copolymer material used in this invention consists of a polypropylene chain.

[0033] In another preferred embodiment, polymer A in the block copolymer material used in this invention consists of an ethylene-propylene copolymer.

[0034] In another preferred embodiment, polymer A in the block copolymer material used in this invention consists of an ethylene 1 -hexene copolymer.

[0035] In another preferred embodiment, polymer A of the block copolymer material used in this invention consists of an ethylene 1 -octene copolymer.

[0036] If desired polymer A may after formation be provided with some polarity by the grafting of unsaturated monomers such as maleic anhydride onto polymer A.

[0037] When one or more higher 1 -alkene monomers are used in conjunction with ethylene or propylene to form polymer A preferably the total proportion of the higher 1-alkene monomers is between 1 and 50 mol%, preferably between 2 and 40 mol%, the remainder of polymer A being derived from ethylene or propylene. When used the amount of the 1-alkene monomer in polymer A preferably ranges from 2 to 15 mole %. A preferred 1-alkene monomer is octene.

[0038] Polymer A of the block copolymer is preferably produced using a metallocene catalyst and suitable metallocene catalysts for the production of polymer A comprise a transition metal, particularly a metal from group IV of the periodic table such as Ti, Zr or Hf, with one or more ligands such as cyclopentadienyl (“Cp”), substituted cyclopentadienyl (including indenyl, fluorenyl and their derivatives), and bridged variants of the above. Additional ligands may be coordinated or bonded to the metal by heteroatoms such as N, O, S or P and may include bridges to Cp-type ligands as above.

[0039] Such catalysts are normally synthesised and stored as a metal dichloride / dialkyl (e.g. dibenzyl) or mono-alkyl-mono-chloride species (“pre-catalyst”). This is activated in solution by addition of a co-catalyst, generally a methylaluminoxane (MAO) or a polymethylaluminoxane (PMAO), but alternatively a non / weakly-coordinating anion may be used such as a combination of a boron containing species such as PhaC+ B(C6Fs)4- and a trialkylaluminium species such as i- (C4H9)3AI. PAINT2242 WO - 24 Sep 2025

[0040] Examples of such catalysts include CP2MCI2, Cp*2MCh, EBIMCI2, Flu(Ph2Me)CpMCl2, and Cp(Me)4(Me2Si)NtBuMCl2, wherein M represents a transition metal. Preferred catalysts are catalysts in which M represents zirconium. An example catalyst is Cp2ZrCh together with a co-catalyst.

[0041] The block copolymers used in this invention may contain other conventional additives such as stabilisers, antioxidants, viscosity modifiers, pigments, dyes, fillers and hardeners.

[0042] The polymer B of the block copolymer used in this invention is of one or more polar monomers and is preferably a copolymer of at least two polar monomers wherein at least one of the monomers ensures the dispersion or the solubility of the block copolymer in the medium in which it is used which may be a solvent or liquid carrier. For example, when the polymer is applied to one or both surfaces of the film it may be applied in a solvent or a carrier. Polymer B preferably contains a monomer that aids the dispersion or solution of the block copolymer. Polymer B may also contain at least one other polar monomer which provides the adhesion between the olefin polymer or copolymer of the film and the coating material to be applied thereto which in the case of paints, inks or adhesives tend to contain polar groups.

[0043] We prefer that at least one monomer of polymer B is an acrylate monomer as these have good reactivity with diisopropenyl benzene which is the preferred material for use in the block copolymer manufacture. In particular, we have found that using butyl acrylate together with acrylic acid is particularly useful as butyl acrylate provides solubility in solvents such as xylene and acrylic acid provides the polarity required to react with functional groups within coating materials such as inks and paints.

[0044] The preferred combination of polymer A and polymer B will depend upon the substrate with which the film is to be used and upon the nature of the coating material to be bonded to the substrate. However, when polymer A is largely based on propylene we prefer that it has a number average molecular weight in the range of 1000 to 13000 preferably 3000 to 5000. Where polymer A is largely based on ethylene we prefer that it has a number average molecular weight in the range 1000 to 10,000 preferably 1000 to 2000. The preferred range for the number average molecular weight of polymer B is 500 to 5000. All molecular weights being measured by NMR.

[0045] We prefer that the block copolymer used in this invention provides a coating of from 0.3 to 20 grams per square meter of the coating of the dry block copolymer. In particular, we prefer that it provides from 1 to 5 more preferably from 1 to 3 grams per square meter. The selection of PAINT2242 WO - 24 Sep 2025 the amount of the block copolymer provided and the composition of the block copolymer will depend upon the nature of the substrate and the coating material. We have however found that good adhesion with polyolefine substrates may be achieved employing a polypropylene film coated with between 0.3-20 grams per square meter of a block copolymer where polymer A comprises polypropylene and polymer B is a terpolymer of butyl acrylate; acrylic acid and 2 hydroxyethyl methacrylate. Good adhesion of the coating material is considered to be achieved when cohesive failure as determined according to ASTM D 4541-22 using a Positest tensile tester occurs within the coating material itself rather than between layers of the structure, or within the substrate bulk itself, showing that the whole adhesive system is stronger than the substrate. This has been found to be achieved with various polyurethane coatings such as the materials Sikaflex 252;221 and 522 available from Sika where cohesive failure within the coating materials occurred under stresses of from 1.8 to 2.5mPa compared to 0.1 to 0.2 mPa when they are applied directly to the untreated polypropylene substrate. Similar improvements in adhesion have been found in bonding coating materials such as epoxy resin adhesives, polyurethane foams, PVC lacquers, solvent based 2KPLI automotive paints and water based automotive paints as well as acrylic spray paints.

[0046] The coating that provides the block copolymer material and the film will be chosen according to the nature of the substrate to which the coating material is to be bonded. The invention is particularly useful in securing coating materials to polypropylene substrates particularly automobile components which have previously required special and expensive techniques which sometimes do not provide adequate adhesion. We have found that the adhesion of the coating materials as previously described to polypropylene substrates can be improved by this invention when the coating materials are to be applied to a range of polypropylene films including monolayer and multilayer films, oriented films, blown and cast films and in some instances treated films such as corona discharge treatment. The preferred thickness of the film again depends upon the nature of the coating material and the substrate and in particular the use to which the final laminated product is to be put. We have however found films of thickness from 20 to 300 microns to be particularly useful.

[0047] Although the invention can be applied to a range of substrates since polypropylene is a widely used material in a range of industries the invention has been extensively aimed at the wide range of industries employing polypropylene. We have found that the invention is applicable to a range of polypropylene substrates comprising propylene homopolymers and copolymers and to such polymers with or without fillers such as glass fibres, flax fibres, carbon fibres, aramid fibres or wood fibres. The substrate may be a composite provided with a polypropylene PAINT2242 WO - 24 Sep 2025 skin as an outer layer perhaps provided on a polymeric foamed structure which may or may not be of polypropylene. The substrate may be a heat sealable film.

[0048] When the coating comprises of film containing the block copolymer any suitable lamination techniques may be used for the lamination of the coating to the substrate. Typical temperatures for the lamination range from 150 °C to 250 °C preferably 170 °C to 230 °C when the coated film is not a heat sealable coating; lower temperature such as temperatures down to 95 °C may be employed if the coated film is heat sealable. The lamination may be performed continuously or as a single moulding depending upon the nature of the substrate and the use to which it is to be put. A static press may be suitable for a single moulding whereas continuous laminating belts are useful for continuous lamination.

[0049] The invention is particularly useful in the economic preparation of components for the automobile and aerospace industries where polyolefine components are used and coating materials such as adhesives and paints are required and to date it has been difficult to obtain adequate and reliable adhesion of the coatings to the substrates. The invention may also be used to improve the adhesion of foams as coating materials to substrates particularly foams providing thermal insulation such as polyurethane foams used for example in refrigerated transport.

[0050] The invention is particularly useful with coating materials containing polar groups and examples of coating materials with which this invention is useful include paints such as automotive paints which may be water based or solvent based. Typical paints include 1 K and 2K paints such as 2K polyurethane paints, acrylic paints and spray paints. Other coatings that may be used are inks such as the typical commercial inks including solvent based inks. The film may also be used to secure adhesive coating materials to substrates, the coating materials include most typical commercial adhesives and other coating materials such as varnishes particularly to secure to polyolefin substrates.

[0051] The block copolymers used in this invention have been found to be useful in promoting the adhesion of coating materials to a variety of substrates. For example, the substrate may include moulded and extruded articles including films and heavy duty sheeting; components of various types for example for automobiles, aircraft and domestic appliances. The substrates may be filled with for example reinforcing fibres such as glass or carbon fibre. The substrates may also contain other conventional additives. PAINT2242 WO - 24 Sep 2025

[0052] The coated films of this invention may be used to improve the adhesion of overmoulded products where two layers are sequentially injected into the mould of an injection moulder; the coating may be used as an intermediate adhesive layer, particularly when it comprises the block copolymer within or on a thermoplastic film.

[0053] The present invention is illustrated by the following Examples.

[0054] Example 1

[0055] This Example demonstrates that sufficient temperature and pressure are required to achieve a cohesive failure

[0056] Experimental: o A block copolymer coating wherein polymer A was a propylene copolymer and polymer B was a terpolymer of butyl acrylate, acrylic acid and hydroxyethyl methacrylate was applied to a polypropylene film using gravure coating. o The coated film was laminated to a polypropylene / glass fibre substrate using a temperature of 100°C o Sika 252 adhesive was applied to the coated film and then tested for adhesive strength using an aluminium test dolly. o After curing, the adhesive strength was measured and found to be significantly less (0.1 MPa) than the adhesive supplier’s quoted 3 MPa tensile strength using ISO527 test method. o The adhesive failure occurred between the coated film and the substrate. o When the curing temperature was raised to 170°C the adhesive failed within the adhesive layer. o This confirms that the lamination temperature and / or pressure is important to performance.

[0057] Example 2

[0058] The film used in Example 1 was used to bond the substrate used in Example 1 to the 3M Scotch Weld Structural adhesive DP 631 ONS 2KPLI coating material when the film was not used the adhesive between the coating material and the substrate the adhesive failed at the interface whereas when the film was used the adhesive failed within the substrate.

[0059] Example 3

[0060] Similar results to Example 2 were obtained when the coating material was a cyanoacrylate adhesive. PAINT2242 WO - 24 Sep 2025

[0061] Example 4

[0062] A formulation was prepared comprising

[0063] 81.2 wt % xylene

[0064] 7.6 wt % of the diblock copolymer used in Example 1

[0065] 7.3 wt % of a terpolymer of butyl acrylate, acrylic acid and hydroxy ethyl methacrylate

[0066] 3.3 wt % of a propylene homopolymer.

[0067] The formulation was applied to one side of a 60 micron thick polypropylene film which was passed through an oven held at 80°C to dry the coating.

[0068] The coated film was then laminated onto a polypropylene sandwich panel by pressure at 190°C with the coated side remote from the panel.

[0069] The panel was then ready for applying a coating material and it was found bond strength with a coating of a 2 KPU adhesive greater than 4.7 mPa cold be achieved in a pull of test and the bond strength of the coating was greater than the bond strength of the composite substrate.

[0070] Additionally, when paint was applied as a coating material there were perfect results in the cross hatch test in that no paint could be removed.

Claims

PAINT2242 WO - 24 Sep 2025CLAIMS1. A laminar structure comprising a substrate bonded to a coating material wherein the bonding is provided by an intermediate layer comprising a block copolymer of structure polymer Bwhere R and R1may be the same or different and each independently represents an alkyl or aryl group, X may be hydrogen or a C1 to C20 alkyl group which may be branched or linear and wherein the aromatic ring substituent joined to Polymer B is positioned meta or para to the aromatic ring substituent joined to Polymer A, characterized in that: a) Polymer A is a polymer or copolymer of an olefine and b) Polymer B is a polymer of a polar monomer comprising one or more of a,p- unsaturated monomers selected from the group consisting of carboxylic acids, styrene, substituted styrene, acrylate, methacrylate, vinyl esters, fumarate esters and maleic anhydride and derivatives thereof, and diene compounds. and from 50 to 90 wt % of a polyolefin resin.

2. A laminar structure according to Claim 1 in which the intermediate layer comprises a thermoplastic film coated with the block copolymer.

3. A laminar structure according to Claim 1 in which the intermediate layer is provided by coating the substrate with a solution or dispersion of the block copolymer.

4. A laminar structure according to Claim 2 in which the intermediate layer has a thickness of from 20 pm to 400 pm preferably 20 pm to 200 pm.

5. A laminar structure according to Claim 1 or Claim 3 in which the intermediate layer contains from 0.1 wt % to 10 wt % of the block copolymer.

6. A laminar structure comprising a substrate and a foam layer bonded together by an intermediate layer as defined in Claim 1.PAINT2242 WO - 24 Sep 20257. A laminar structure according to Claim 6 for use in refrigerated transport.

8. A laminar structure according to any of the preceding claims wherein the substrate comprises a polyolefine substrate.

9. The use of a block copolymer as defined in Claim 1 to provide adhesion between a polyolefine substrate and a coating material.

10. A process for the production of a coated substrate comprising laying up a film coated with a block copolymer as defined in Claim 1 on the surface of a substrate and optionally applying pressure at a temperature in the range of 110 °C to 230 °C to bond the coated film to the substrate and subsequently applying a coating material on the exposed surface of the coated film.11 . A process according to Claim 10 wherein the coating material is bonded to the film by applying pressure at a temperature in the range of 80 °C to 166 °C preferably 110 °C to 130 °C.

12. A structure comprising a film coated with a copolymer as defined in Claim 1 wherein i) polymer A comprises a chain of ethylenic or propylenic structural units, optionally copolymerised with higher 1 -alkene co-monomers, preferred chains are polyethylene or polypropylene or propylene / ethylene copolymer chains and ii) polymer B is derived from two or more a,p - unsaturated polar monomers selected from styrene, substituted styrene, unsaturated esters such as acrylate, methacrylate esters such as butyl acrylate, methyl(meth) acrylate, 2-ethyl hexyl methacrylate, glycidyl methacrylate, poly(ethylene glycol) methacrylate, butyl methacrylate, and hydroxyethyl acrylate and vinyl esters, fumarate esters, itaconate esters, maleic anhydride, unsaturated acids such as acrylic acid and methacrylic acid ionomers and diene compounds and derivatives thereof, polymer B may comprise a copolymer of such unsaturated monomers with an alkene such as a C2 to C8, preferably a C2 to C6 alkene; styrene is considered to be a polar monomer as it has a dipole moment and can be polymerised with a free radical catalyst.

13. A film according to Claim 12 wherein polymer A comprises a chain of ethylenic or propylenic structures or an ethylene / propylene copolymer chain optionally interruptedPAINT2242 WO - 24 Sep 2025 by one or more structural units derived from higher 1 -alkene comonomers such as hexene or octene and polymer B comprises a chain of structural units derived from two or more a,p - unsaturated polar monomers selected from unsaturated carboxylic acids, styrene, substituted styrene, unsaturated esters such as acrylate and methacrylate esters, vinyl esters, fumarate esters, itaconate esters, maleic anhydride, unsaturated acids such as acrylic acid and methacrylic acid and diene compounds and derivatives thereof, polymer B may be a copolymer of such monomers with an alkene such as a C2 to C8 alkene.

14. A film according to Claim 12 or Claim 13 wherein polymer B is a copolymer of at least three monomers with at least some of the monomers providing pendant polar groups on polymer B for interaction with the polar groups in the coating materials.

15. A laminar structure according to any of Claims 1 to 7 wherein the substrate is predominantly comprised of propylene and polymer A is also predominantly propylene.

16. A laminar structure according to any of Claims 1 to 7 wherein the substrate is predominantly polyethylene and polymer A is predominantly comprised of polyethylene.

17. A laminar structure according to Claim 15 wherein polymer A has a number average molecular weight in the range of 1000 to 13000 preferably 3000 to 5000.

18. A laminar structure according to Claim 14 in which polymer A has a number average molecular weight in the range 1000 to 10,000 preferably 1000 to 2000.

19. A laminar structure according to any of Claims 1 to 7 wherein the coating materials contain polar groups and are selected from water based or solvent based automotive paints.

20. A laminar structure according to Claim 19 in which the paint is a paint which can be a 1 K or 2K paint such as 2K polyurethane paints, acrylic paints, spray paints, adhesives and varnishes.

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