Thermoplastic/thermoset composite systems are useful in applications such as piping, high pressure gas cylinders, and chemical storage tanks. For these applications, composites are frequently made according to a two step process. First, an article is formed from the thermoplastic by extrusion, blow moulding, rotomoulding, or some other conventional melt processing technique. In a second step, the thermoplastic is wrapped or coated with the thermoset material. Often, the thermoset is also a composite system containing glass or carbon fibres. The result is a composite structure which can be readily fabricated into a wide variety of shapes and sizes, yet exhibits high strength in combination with the intrinsic properties of the thermoplastic substrate (e. g. impact, chemical and stress crack propagation resistance).

One of the critical design parameters which governs the ultimate properties of the thermoplastic/thermoset composite structure is the strength of the interface between the thermoplastic and thermoset. Strong interfacial bonds have the desirable characteristic of evenly distributing and transferring stress from the thermoplastic to the high modulus thermoset composite.

Thus, strong interfacial bonds increase the service pressures and longevity of fabricated parts.

US-A-5405700 proposes a method for applying epoxy systems to a solid polyketone polymer substrate using a multifunctional amine. This method involves the manual handling and application of free amine to the surface of

a polyketone substrate. The amines disclosed and suggested are relatively low molecular weight liquids, which form vapours. They are normally used as such, that is e. g. without dilution in a high boiling liquid, which could reduce the formation of the amine vapour. The handling will give HSE problems, in particular in view of the exposure of workers to amine when manually applying the free amine to the polyketone substrate. Lessening contact and exposure to the amine is highly desirable.

This is particularly the case in applications such as the manufacture of reinforced pipe.

The invention relates to a process for the production of a composite comprising applying an epoxy resin to an aminated polymer layer of a polyketone-aminated polymer substrate in which substrate the layer of an aminated polymer is bonded to a layer of a polyketone. The invention also relates to a multilayer composite comprising at least a polyketone layer, an epoxy resin, and an aminated polymer which is bonded to the polyketone and to the epoxy resin together.

The epoxy resins which are useful in this invention can be saturated or unsaturated, aliphatic, cyclo- aliphatic, aromatic or heterocyclic, and may bear substituents which do not materially interfere with the reaction with the aminated polymer.

Suitable epoxy resins can be prepared by the reaction of epichlorohydrin with mononuclear di-and trihydroxy phenolic compounds such as resorcinol and phloroglucinol, polynuclear di-, tri-and polyhydroxy phenolic compounds, such as bis (p-hydroxyphenyl) methane and 4,4'-dihydroxy- biphenyl, or aliphatic polyols such as 1,4-butanediol and glycerol.

In particular, suitable epoxy resins include glycidyl ethers which can be prepared by the reaction of epichlorohydrin with a compound containing at least one

hydroxyl group carried out under alkaline reaction conditions. The epoxy resin products obtained when the hydroxy group-containing compound is bisphenol-A ("BPA") are represented below by structure I wherein n is zero or a number greater than 0, commonly in the range of from 0 to 10, preferably in the range of from 0 to 6, and more preferably in the range between 1 and 4.

Epoxy resins suitable for the practice of the invention have a molecular weight generally within the range of from 86 to 10,000, preferably from 200 to 1500.

The commercially-available epoxy resin EPON 828 epoxy resin, a reaction product of epichlorohydrin and BPA having a molecular weight of 400, an epoxide equivalent (ASTM D-1652) of 185-192, and an n value (from formula I above) of about 0.2, is a preferred epoxy resin (EPON is a trade mark). The commercially available EPON 9500 epoxy resin, a reaction product of epichlorohydrin and BPA having an epoxide equivalent (ASTM D-1652) of 175-190 with a viscosity of 4,000-9,000 cP at 25 °C and a specific gravity of 1.16 g/ml at 25 °C is another preferred epoxy resin.

The epoxy resin components of the instant inventions are generally cured using a curing agent. The best choice and methods for curing agent is within the skills of one skilled in the art depending upon the precise epoxy resin selected and the purpose and conditions of its use (cf.

Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A9, pp. 547 ff., which is herein incorporated by reference). Most suitable curing agents are polyamines,

in particular having primary and/or secondary amino groups, with the optional presence of an accelerator.

These polyamines typically have at least 2 nitrogen atoms per molecule and at least two amine hydrogen atoms per molecule. The nitrogen atoms are linked by divalent hydrocarbyl groups and may be linked to aliphatic, cycloaliphatic or aromatic. The polyamines contain typically at least 2 carbon atoms per molecule.

Preferably the polyamines contain 2 to 6 amine nitrogen atoms per molecule, and 2 to 50 carbon atoms.

Examples of the polyamines useful as a curing agent for epoxy resins include aliphatic polyamines such as ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, dipropylene triamine, tributylene tetramine, hexamethylene diamine, dihexamethylene triamine, 1,2-propane diamine, 1,3-propane diamine, 1,2-butane diamine, 1,3-butane diamine, 1,4-butane diamine,- 1,5-pentane diamine, 1,6-hexane diamine, 2-methyl-1,5- pentanediamine, 2,5-dimethyl-2,5-hexanediamine and the like; cycloaliphatic polyamines such as isophorone- diamine, 4,4'-diaminodicyclohexylmethane, menthane diamine, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, and diamines derived from"dimer acids" (dimerized fatty acids) which are produced by condensing the dimer acids with ammonia and then dehydrating and hydrogenating; adducts of amines with epoxy resins such as an adduct of isophoronediamine with a diglycidyl ether of a dihydric phenol, or corresponding adducts with ethylenediamine or m-xylylenediamine; araliphatic polyamines such as 1,3-bis (aminomethyl) benzene; aromatic polyamines such as 4,4'-methylenedianiline, 1,3-phenylenediamine and 3,5-diethyl-2,4-toluenediamine; amidoamines such as condensates of fatty acids with diethylenetriamine, triethylenetetramine, etc.; and polyamides such as

condensates of dimer acids with diethylenetriamine, triethylenetetramine, etc. Some commercial examples of polyamines include EPI-CURE Curing Agent 3140 (EPI-CURE is a trade mark) (a dimer acid-aliphatic polyamine adduct), EPI-CURE Curing Agent 3270 (a modified aliphatic polyamine), EPI-CURE Curing Agent 3274 (a modified aliphatic polyamine), EPI-CURE Curing Agent 3295 (an aliphatic amine adduct), EPI-CURE Curing Agent 3282 (an aliphatic amine adduct), EPI-CURE Curing Agent 3055 (an amidoamine), EPI-CURE Curing Agent 3046 (an amidoamine), EPI-CURE Curing Agent 3072 (modified amidoamine) and EPI-CURE Curing Agent 3483 (an aromatic polyamine) available from Shell Chemical Company. A preferred curing agent is bis (4-aminocyclohexyl) methane available from Air Products, Inc. under the trade mark AMICURE PACM.

Mixtures of polyamines can also be used.

In most cases the ratio of the quantities of curing agent and epoxy resin can be determined by assuming that each available site on the curing agent, e. g. primary and/or secondary amino groups, can react with an epoxy group. Typically the molar ratio of the available site on the curing agent to epoxy groups is from 0.2-5, preferably from 0.5-2, in particular from 0.8-1.25.

The polyketone polymers which are employed in this invention are of an alternating structure and contain substantially one molecule of carbon monoxide for each molecule of ethylenically unsaturated hydrocarbon. The portions of the polymer attributable to carbon monoxide alternates with those attributable to the ethylenically unsaturated hydrocarbon.

It is possible to employ a number of different ethylenically unsaturated hydrocarbons as monomers within the same polymer but the preferred polyketone polymers are copolymers of carbon monoxide and ethylene or terpolymers of carbon monoxide, ethylene and a second

ethylenically 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 combinations of four, five or more monomers. Such polyketone polymers are aliphatic in that there is an absence of aromatic groups along the polymer backbone.

However, polyketones may have aromatic groups substituted or added to side chains and yet still be considered aliphatic polyketones.

When the preferred polyketone terpolymers are employed, there will be within the terpolymer at least 2 units incorporating a moiety of ethylene 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 hydrocarbon. The polymer chain of the preferred polyketone polymers is therefore represented by the repeating formula -+-CO-4--CH2-CH2-)---CO-f-G-i-}-y- where G is the moiety of ethylenically unsaturated hydrocarbon of at least three carbon atoms polymerized through the ethylenic unsaturation and the ratio of y: x is no more than 0.5. Preferred ratios of y: x are from 0.01 to 0.1. The-CO (CH2-CH2) units and the-CO (Gf units are found randomly throughout the polymer chain.

When copolymers of carbon monoxide and ethylene only 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. The precise nature of the end groups does not appear to influence the properties of the polymer to any considerable 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 the 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, which are herein incorporated by reference. US-A-4808699 teaches the production of linear alternating polymers by contacting ethylenically unsaturated compounds and carbon monoxide in the presence of a catalyst comprising a Group VIII metal compound, an anion of a nonhydrohalogenic 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 ethylene in the presence of one or more hydrocarbons having an ethylenically unsaturated group with a similar catalyst.

The aminated polymers of this invention are made by contacting an amine with a suitable polymer. Suitable polymers are those which are reactive to amines and which can be processed in the melt at or near the corresponding melt processing temperature of the polyketone as described further below. A broad range of polymers are useful as the aminated polymers of this invention.

Essentially, the aminated polymer must have amine functionality attached to it which is reactive with polyketone and amine functionality which is reactive with epoxy resin. One of ordinary skill will then match the aminated polymer having the melt processing temperature within the working range of the melt processing temperature of the polyketone to which it will be applied.

The most preferred aminated polymers are generally prepared by melt blending an acid copolymer with a suitable amine. Although monocarboxylic acids are preferred monomers for the acid copolymer, the acid monomer may comprise a polycarboxylic acid such as a dicarboxylic acid or a tricarboxylic acid. The other monomer units of the acid copolymer are preferably ethylenically 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-CR1CO2H, wherein R is a Cl-lo ethylenically unsaturated hydrocarbon and R1 is a C1_6 alkyl group are the preferred acid copolymers of this inventions with random poly (ethene-methacrylic acid) and random poly (propene-methacrylic) acid being the most preferred acid copolymers.

The acid content of the acid copolymer ranges from 0.015-4.7 mole% acid. Preferably, the acid content comprises 0.34-1.73 mole% and more preferably

1.15-1.55 mole%. All references to mole% acid content herein are based on a calculation of the number of moles of the acid monomer relative to the total number of moles of all monomer units forming the polymer. Alternatively, the acid content can be adjusted by intermixing various quantities of polymer such that the total acid content for the blend is in accord with the foregoing percentages mole% acid.

The amine component of the amine modified acid copolymer has at least two amine functional groups and is suitably of the form NH2-R-NH2 wherein R comprises C2-24 substituted or unsubstituted aliphatic, cycloaliphatic or aromatic groups or combinations thereof and may contain hetero atoms such as S, N, and 0. Depending upon the composition of R, more than two amino groups may be present in the amine. A few examples of suitable amines are 1,4-diaminobutane; 1,10-diaminodecane; 4,4'-diaminodiphenyl ether; 1,12-diaminododecane; diaminoethane; 1,7-diaminoheptane; 1,6-diaminohexane; 1,3-diamino-2-hydroxypropane; 2,3-diaminonapthalene; 1,8-diaminooctane; 1,5-diamino- pentane; 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.

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 acid copolymers used in this invention.

An effective amount of amine is reacted with the polymer used to prepare the aminated polymer to achieve the desired level of adhesion. The quantity of amine is preferably low. While a stoichiometric excess of amine can be used it is a particular advantage of this

invention that as little as 0.01 mole% amine/mole of reactive sites on the polymer to be used as the amine modified polymer (acid monomer, in the acid copolymer) can be used with good effect in some applications. One of ordinary skill in the art will recognize applications in which greater amounts of adhesion are desired and will increase the relative proportion of amine accordingly.

However, in the preferred embodiment maximum adhesion is generally attained through the addition of no more than a stoichiometric quantity of amine (based on reactive sites on the polymer to be used as the amine modified polymer).

The amine modified acid copolymer of this invention may be made by melt blending acid copolymer with the amine by any suitable means, for example via extruder or Brabender mixer. A suitable temperature for melt blending may be, for example, above 100 °C, typically above 120 °C, but it is generally below 300 °C. A preferred temperature range is 150-220 °C. If desirable, the preparation of the amine modified polymer may be effected simultaneously with a melt processing step which is carried out when preparing the composite of this invention as set forth below.

Other aminated polymers useful in the practice of this invention include aminated polyolefins and aminated modified polyolefins such as aminated carbonylated polyethylene (e. g. the random polyketones obtained via radical polymerization), aminated maleated polyethylene and aminated maleated polypropylene. Polyamides are also useful in this regard. These include polyamides with a short aliphatic chain segment; polyamide-AB such as polyamide-6; polyamide-AABB such as polyamide-6,6; and a polyamide with a long aliphatic chain segment such as polyamide-12 (herein A is used to represent the amine and B is used to represent the carboxyl group of the polyamide). A terpolymer comprising each of these

particular portions is most preferred. The polyamide may be made sufficiently reactive with the epoxy resin by treating it with and acid anhydride or amine in the manner disclosed in US-A-2955101 and US-A-3028342 (both of which are incorporated herein by reference). Poly- urethanes, polyether polyamines and polyoxyalkylene- polyamines are further examples of polymers having amine functionalities which also provide utility as the aminated polymers of this invention. The latter class of polymers are produced by reaction between an aldehyde and a polyoxyalkylene polyamine followed by hydrogenation of the product. Such polymers are described in US-A-3660319 and US-A-3832402. Polyether polyamines are produced by the conversion of polyether polyols via reaction with ammonia (as described US-A-3654370 and US-A-4153581, incorporated herein by reference).

The weight average molecular weight of the aminated polymer is typically 2000-1,000,000 as determined by gel permeation chromatography. The crystalline melting point of the aminated polymer is 80-300 °C, as measured by DSC, with 80-220 °C being preferred. If the aminated polymer does not have a crystalline melting point, its glass transition temperature is-80 to 200 °C (as measured by DSC). These parameters are most preferably met through the use of poly (ethene-methacrylic acid) available from DuPont as NUCREL acid copolymers and having an acid content of about 4 % wt and a melt flow index of about 0.5-7 g/lOmin (based on ASTM D1238) with 1-4 being most preferred (NUCREL is a trade mark).

The composite and any of its components may also have present other common polymer additives such as fillers, extenders, lubricants, pigments, plasticizers, and other polymeric materials added to the compositions to improve or otherwise alter the properties of the compositions.

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 epoxy resin forms a second layer, and both layers are bonded together by an intermediate layer of amine modified polymer, which means that the amine modified polymer functions as an adhesive layer (tielayer).

Compositions having four or more layers may also be formed with additional intermediate layers.

Such multilayer structures can be made, for example, by applying onto a polyketone layer the amine modified polymer (suitably by extruding (or co-extruding) a melt of the amine modified polymer onto the polyketone (melt) layer) which amine modified polymer will subsequently be in contact with epoxy resin which is undergoing cure.

Epoxy resin cure is initiated by exposure to a suitable curing agent. Initiation and completion of cure is best accomplished by intimately mixing epoxy resin and curing agent prior to application to the extruded amine modified polymer/polyketone composite. The most preferred method of making multilayer structures is by a co-extrusion process in which a melt of the amine modified polymer is co-extruded with a melt of polyketone to form an article such as a pipe or tube. The article may then be wrapped in fibre reinforcement, uncured epoxy resin is applied to the wrap, and then cured by contact with a curing agent under suitable curing conditions, effecting cure of the epoxy resin and bonding between the epoxy resin and the polyketone-aminated polymer. In another embodiment, tape or ribbon of aminated polymer is applied to a formed polyketone article. The article is then sprayed with an epoxy and cured by contact with a curing agent under suitable curing conditions. Depending upon the curing agent selected, this may require the application of heat.

In the preferred embodiment in which EPON 9500 Epoxy

Resin is cured with bis (4-aminocyclohexyl) methane, cure is readily affected by exposure to 120 °C for periods of about an hour.

In the co-extrusion process, the 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 polyketone followed by a layer of amine modified polymer, followed by a layer of polyketone regrind. The epoxy resin would then be applied to this multilayer structure in accordance with this invention and applying known epoxy application techniques. 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 thermoplastics together with those of thermosets.

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 |J, 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 from 5-1000 p. m.

The invention is further illustrated by the following non-limiting examples and table.

EXAMPLE 1 (Polyketone formation and moulding) A terpolymer of carbon monoxide, ethene, and propene was produced in the presence of a catalyst composition formed from palladium acetate, the anion of trifluoro- acetic acid and 1,3-bis (diphenylphosphino) propane. The melting point of the linear terpolymer was 220 °C and it had a limiting viscosity number (LVN) of 1.75 dl/g, measured at 60 °C in m-cresol. The polyketone was injection moulded into standard flex bars (3 mm x 12 mm x 125 mm).

EXAMPLE 2 (Application of aminated polymer) 12 grams of aminated maleated polyethylene was placed in the center of a 0.33 mm mould at a temperature of 177 °C (350 °F) under increasing force for three minutes to form a sheet. The sheet was removed and applied to the polyketone flex bars of Example 1 by compression moulding at 200 °C (390 °F) for 90 seconds. Polyketone-aminated polymer flex bars were thus prepared. The co-extrusion process described in US-A-5369170 (incorporated herein by reference) attains the same result. This example illustrates an advantage of using the method of this invention; the elimination of handling and applying free amines.

EXAMPLE 3 (Application of aminated polymer) 12 grams of a reaction product of 0.25 % wt (based on weight of amine and polymer) 4,9-dioxa-1,12-diamino- dodecane and random poly (ethene-methacrylic acid) copolymer having 3.11 mole% acid content and a melt flow index of 3, commercially available from Du Pont as NUCREL 903 polymer, was placed in the center of a 0.33 mm mould at a temperature of 143 °C (290 °F) under increasing force for three minutes to form a sheet. The sheet was removed and applied to the polyketone tensile bars of Example 1 by compression moulding at 177 °C (350 °F) for 90 seconds. Polyketone-aminated polymer plaques were thus

prepared. The co-extrusion process described in US-A-5369170 (incorporated herein by reference) attains the same result.

This example illustrates an advantage of using the method of this invention. The handling of free amines is reduced to feeding the amine to a reaction mixture in which an acid polymer is reacted with the amine, as opposed to applying the free amine over a possibly large surface of a polyketone article.

EXAMPLE 4 (Epoxy resin application) The polyketone-aminated polymer plaques of Examples 2 and 3 were formed into composites of polyketone-aminated polymer-epoxy resins by lap-gluing two of each type of plaque with a fibre glass cloth sandwiched between them.

In this process, both bars that were joined received a thin coat of an epoxy resin commercially available from Shell Chemical Company under the name EPON 9500 5 cm from the end of each bar. EPON 9500 epoxy resin is the reaction product of epichlorohydrin and bisphenol-A. The fibre glass cloth was also imbedded in the liquid epoxy, then coated with more epoxy. A total of about 34 grams of epoxy resin was used in this process. This 34 grams of resin epoxy was preblended with about 10 grams of bis (4- aminocyclohexyl) methane (commercially available from Air Products as AMICURE PACM) prior to the application to the fibre glass cloth. The combination of the flex bars and epoxy treated fibre glass were then cured under pressure of binder clips in an oven for one hour at 120 °C. After curing and cooling to room temperature, the plaques were subjected to the lap shear testing of ASTM D1002 with a crosshead speed of 1.27 mm/min. The samples made with the polyketone-aminated polymer of Example 2 displayed a lap shear strength of 3.13 MPa. The samples made with the polyketone-aminated polymer of Example 3 displayed a lap shear strength of 3.67 MPa and displayed yield behavior.

This illustrates the excellent strength of the composites made according to this invention.

EXAMPLE 5 (Co-extrusion--prophetic) A modified acid copolymer is co-extruded with polyketones of Example 1 to form a polyketone-aminated polymer substrate (the aminated polymer is the outer layer). The acid copolymer is a random poly (ethene- methacrylic acid) copolymer having about 3.11 mole% acid content and a melt flow index of 3 and is commercially available from Du Pont as NUCREL 903 polymer. The acid copolymer is co-extruded with 4,9-dioxadiamino-1,12- dodecane, commercially available from BASF.

The co-extrusion of polyketone and amined modified acid copolymer is conducted using two single screw extruders (2 x 38 mm extruders and a 25 mm extruder) and a multilayer manifold and die.

The polyketone is processed at a melt temperature between 240 °C and 260 °C. The amine modified acid copolymer (as a tielayer) is processed through the 25 mm extruder at 160 °C. Tubing is thus made from the co- extruded polyketone-aminated polymer substrate.

This example illustrates an advantage of using the method of this invention; the elimination of handling free amines.

EXAMPLE 6 (Epoxy resin application--prophetic) An epoxy resin commercially available from Shell Chemical Company under the name EPON 9500 epoxy resin is applied to the tubing of Example 5. The epoxy resin is preblended with a curing agent comprising bis (4-amino- cyclohexyl) methane. The combination is applied to the tubing which is then cured in an oven for one hour at 120 °C. Testing will indicate high adhesion between polyketone and epoxy system permitting significant flexing without delamination.

EXAMPLE 7 (Prophetic) The polyketones of Example 1 are co-extruded with a random poly (ethene-methacrylic acid) copolymer having about 3.11 mole% acid content and a melt flow index of 3 (commercially available from Du Pont as"NUCREL 903" polymer) aminated with 0.25 wt%, 4,9-dioxadiaminododecane commercially available from BASF.

The co-extrusion is conducted using two single screw extruders and a multilayer manifold and pipe die. A tubing of nominal outer diameter of 7.5-8.0 cm is produced.

The polyketone is processed at a melt temperature between 240 °C and 260 °C. The amine modified acid copolymer (as a tielayer) is processed through the extruder at 160 °C. The two streams are processed through the die head at about 260 °C. The pipe is left to cool for about an hour.

The pipe is then wrapped with a conventional fibre glass wrapping used for producing fibre reinforced pipe.

An epoxy resin commercially available from Shell Chemical Company under the name EPON 828 Epoxy Resin is then applied to the wrapping by brush until the wrapping is soaked through. A suitable stoichiometric quantity of meta-xylylenediamine is preblended with the epoxy resin.

Cure is conducted about one hour at 120 °C. A fibre reinforced pipe is produced with high adhesion between polyketone and epoxy system permitting significant flexing without delamination and exhibiting excellent chemical resistance and impact strength. The pipe has excellent burst strength even after such flexion.