Cross-linkable poly(aryl ether ketone)s and articles made therefrom

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. application No. 60/935,456 filed August 14, 2007, and of Indian application No. 1883/MUM/2007, filed September 26, 2007, the whole content both applications being herein incorporated by reference for all purposes. BACKGROUND OF THE INVENTION:

Polymers, particularly plastics are usually linear long chain molecules of high molecular weights. A branched polymer molecule is typically composed of a main chain with one or more substituent side chains or branches. Polymer bulk properties are strongly dependent upon the polymer chain structure and mesoscopic behavior. A number of qualitative relationships between structure and properties are commonly met. For example, increasing chain length tends generally to decrease chain mobility, increase strength and toughness, and increases the glass transition temperature. This is generally explained as the result of the increase in chain interactions such as Van der Waals attractions and entanglements that come with increased chain length. These interactions tend to fix the individual chains more strongly in position and resist deformations and matrix breakup, both at higher stresses and higher temperatures. The linearity gives thus generally some advantages, notably greater crystallization and therefore mechanical strength, and better thermal stability. In general, branching of polymer chains also affects the bulk properties of polymers. While long chain branches may increase the polymer strength due to an increase in the number of entanglements per chain, random length and atactic short chains may reduce polymer strength due to disruption of organization. Short side chains may likewise reduce crystallinity due to disruption of the crystal structure. On the other hand, reduced crystallinity may be associated with increased transparency due to light scattering by small crystalline regions ; the presence of branches on linear polymeric chains might thus also, at least theoretically and for certain polymers, result in some particular advantages. Specialty plastics (glass transition temperature >160 C if amorphous, melting point > 250 ⁰ C, if crystalline), have high temperature processing requirements (>300 C), due to the structural features with groups which are

essentially non-reactive. Thus, in general, groups such as -OH, -COOH, -CN, and others are carefully avoided. The presence of such reactive groups on the polymer chains is commonly reported to lead to rapid uncontrolled cross-linking or degradation. Some side effects like crumbling of melts into powders are also commonly reported. The specialty polymers which are appreciated are generally linear and rigorously end capped materials, because these ones can maintain their structures during the processing in extrusion, injection molding, and show very high thermal stability at temperatures as high as 380 C without change in melt viscosities for 60-120 minutes under high shear conditions. In contrast, branched specialty plastics are generally disliked ; the main reason for this is reduced thermal stability of branched polymers, due to reactive branch points creating cross-linking, degradation or color problems at high temperature processing.

Poly(aryl ether ketone) s (PAEK) have been known for many years. Poly(ether ether ketone) (PEEK) and poly(ether ketone) (PEK) are the most common PAEK. PEK and PEEK are high-strength, radiation-resistant specialty engineering plastics whose structures combine both ether and ketone groups. Both are thermally stable and highly resistant to chemicals. PAEK can be prepared from a variety of starting materials, either via a nucleophilic route or an electrophilic route. PEEK, the most commercially significant PAEK, is usually prepared using a nucleophilic route. It may also be prepared via an electrophilic route. Usually, PEEK prepared by these two routes are essentially linear and feature very high thermal stability.

The Applicant has surprisingly found that certain shaped articles, namely at most two dimensional shaped articles like coatings, films and filaments, can be easily made from poly(aryl ether ketone) s comprising chains which comprise more than two reactive end groups. Unexpectedly, these poly(aryl ether ketone)s feature some outstanding advantages, in particular lower solution viscosities but higher melt viscosities at lower shear rates, improved mechanical and chemical resistance as compared to linear poly(aryl ether ketone)s of similar molecular weight. As compared to linear poly(aryl ether ketone) s of similar molecular weight, the poly(aryl ether ketone)s of the present invention feature also an improved melt strength, which makes them especially suitable for film forming, coating or blow molding ; they feature also a lower solution viscosity allowing the preparation of solutions with a higher solid content.

DESCRIPTION OF THE INVENTION

A first aspect of the present invention is related to an essentially at most two dimensional shaped article, or part of shaped article, comprising a material comprising a cross-linked, generally thermoset, poly(aryl ether ketone).

Another aspect of the present invention is related to different methods for the preparation of said at most two dimensional article, or part of shaped article.

The poly(aryl ether ketone) s of the present invention are any polymers of which more than 50 wt. % of the recurring units are recurring units (Rl) comprising at least one carbonyl group in-between two arylene groups, said recurring units (Rl) being of one or more of the following formulae :

wherein :

- Ar is independently a divalent aromatic radical selected from phenylene, biphenylene or naphthylene,

- X is independently O, C(=O) or a direct bond,

- n is an integer of from 0 to 3,

- b, c, d and e are 0 or 1,

- A -

a is an integer of 1 to 4, and preferably, d is 0 when b is 1.

Recurring units (Rl) may notably be chosen from

(XIII)

(XIV)

(XV)

(XVI)

(XVII) (XVIII)

and

Preferably, recurring units (Rl) are chosen from :

(VI)

and

More preferably, recurring units (Rl) are :

Preferably more than 70 wt. %, and more preferably more than 85 wt. % of the recurring units of the poly(aryl ether ketone) are recurring units (Rl). Still more preferably, more than 90 wt. % of the recurring units of the poly(aryl ether ketone) are recurring units (Rl). The poly(aryl ether ketone) s of the present invention may be notably poly(ether ether ketone)s, poly(ether ketone)s or poly(ether ketone ketone)s. For the purpose of the present invention, a poly(ether ether ketone) (PEEK) is intended to denote any polymer of which more than 50 wt. % of the recurring units are recurring units (Rl) of formula (VII), a poly (ether ketone) (PEK) is intended to denote any polymer of which more than 50 wt. % of the recurring units are recurring units (Rl) of formula (VI) and a poly (ether ketone ketone) (PEKK) is intended to denote any polymer of which more than 50 wt. % of the recurring units are recurring units (Rl) of formula (IX).

Good results were obtained when the poly(aryl ether ketone) s of the present invention were polymers of which more than 90 wt. % of the recurring units were recurring units (Rl) comprising at least one carbonyl group in- between two arylene groups, said recurring units (Rl) being of one or more of the formulae (VI) to (XXI), preferably of one more of the formulae (VI), (VII) and (IX), and more preferably of formula (VII). The poly(aryl ether ketone) s of the present invention can be amorphous

(i.e. it has no melting point) or semi-crystalline (i.e. it has a melting point). They are usually semi-crystalline; the case being, their melting point is advantageously

greater than 150 ⁰ C, preferably greater than 25O ⁰ C, more preferably greater than 300 ⁰ C and still more preferably greater than 325 ⁰ C.

The above considerations on the poly(aryl ether ketone)s of the present invention, and on their recurring units (Rl), concern equally the cross-linked poly(aryl ether ketone) and the cross-linkable poly(aryl ether ketone) of the present invention, as detailed hereinafter.

For the purpose of the present invention, the term "cross-linked poly(aryl ether ketone)" is intended to denote a poly(aryl ether ketone) in which chemical links have been established between the molecular chains of the polymer. The cross-linked poly(aryl ether ketone) is preferably a thermosetting resin. When extensive, as in most thermosetting resins, cross-linking makes one infusible super-molecule of all the chains forming a three-dimensional or network polymer, generally by covalent bonding.

For the purpose of the present invention, the term "cross-linkable poly(aryl ether ketone)" is intended to denote a poly(aryl ether ketone) which can be cross- linked. Cross-linkable poly(aryl ether ketone)s cross-link generally under the influence of heat, catalysis, irradiation with high-energy electron beams, and/or chemical cross-linking agents such as organic peroxides.

For the purpose of the present invention, the term "reactive end groups" is intended to denote reactive groups that are located at extremities of polymer chains and reactive groups that are located on the polymer chains themselves that are able to react under high temperatures, above the polymer melting temperature. In particular, mention may be made to hydroxyl groups, carboxylic acid end groups, and halogens. The cross-linkable poly(aryl ether ketone) of the present invention features advantageously at least two reactive end groups on each one of its chains, preferably at least three and more preferably at least four reactive end groups. The cross-linkable poly(aryl ether ketone) of the present invention thus presents for example at least one -COOH end group and at least one -OH group located in a polymer chain.

The cross-linkable poly(aryl ether ketone) useful to the present invention can be prepared by 4 methods, out of which two comprise a nucleophilic polymerization and two other ones comprise an electrophilic polymerization. Method (Ml) to prepare the cross-linkable polvCaryl ether ketone). The method (Ml) for preparing a cross-linkable poly(aryl ether ketone) comprises a nucleophilic polymerization of i) at least one polyfunctional

aromatic compound having at least three reactive groups selected from hydroxyl and halogen groups ; with ii) at least one dinucleophile and optionally iii) a difunctional aromatic compound, wherein at least one of the two functional groups comprises a halogen, such as the method described in U.S. Patent Application 10/779207, the whole content of which is herein incorporated by reference.

The method (Ml) allows the preparation of a cross-linkable poly(aryl ether ketone) which is capable of undergoing curing reactions (cross-linking). The cross-linkable poly(aryl ether ketone) is advantageously prepared in a single step utilizing mostly commercially available starting materials. The method (Ml) requires the polymerization of a polyfunctional aromatic having at least three functional groups or, preferably, the copolymerization thereof with a difunctional aromatic compound using a dinucleophile, preferably a diol, which acts as a linking agent. By selecting the proportions of each of the components, a stable polymer or copolymer is provided having the desired degree of workability prior to curing and which can subsequently cured into a thermally stable material having a high glass transition temperature.

The method (Ml) requires the use of a polyfunctional aromatic compound having at least three functional groups ; the functional groups of the polyfunctional aromatic compound may comprise a combination of one halogen and two hydroxyl groups, or preferably two halogens and one hydroxyl group, or more preferably three halogens. The halogen(s) may be selected from the group consisting of Br, I, Cl and F ; they are preferably selected from the group consisting of Cl and F ; more preferably, they are fluorine. The polyfunctional aromatic compound of method (Ml) is advantageously free of any cyclic heteroatom ; a cyclic heteroatom is intended to denote any heteroatom (typically, but not exclusively, nitrogen, oxygen, sulfur...) that is part of the cycle of a cyclic molecule.

The polyfunctional aromatic compound of method (Ml) is selected so as to have electron withdrawing properties and can thus include, but is not limited to, a sulfone, carbonyl or phosphine oxide group. The polyfunctional aromatic compound of method (Ml) includes preferably at least one carbonyl group.

For good reactivity, the functional groups of the polyfunctional aromatic compound of method (Ml) are preferably in the ortho or para positions in the rings relative to the electron withdrawing groups.

The polyfunctional aromatic compound of method (Ml) includes advantageously several halogen groups, preferably several fluorine groups. More preferably, all the functional groups of the polyfunctional aromatic compound of method (Ml) are fluorine.

The polyfunctional aromatic compound of method (Ml) may be selected from the group consisting of trifunctional aromatic compounds, tetrafunctional aromatic compounds, pentafunctional aromatic compounds, and hexafunctional aromatic compounds.

Non-limiting examples of trifunctional compounds useful for method (Ml) are:

wherein B may be C=O or SO ₂ , and B is preferably C=O ; out of these trifunctional compounds,

F ^N F where B is C=O is the most preferred. Non-limiting examples of tetrafunctional aromatic compounds useful for method (Ml) of the present invention are :

wherein B is independently selected from C=O and SO ₂ , and X is is independently selected from F and Cl ; in particular, (i) in the first formula, all the B may be equal to C=O while all the X are equal to F, or all the B may be equal to SO ₂ while all the X are equal to Cl , and (ii) in the second formula, B may be equal to C=O while all the X are equal to F, or B may be equal to SO ₂ while all the X are equal to Cl ; out of these tetrafunctional compounds, the compound of formula

where B is C=O and all the X are equal to F is the most preferred.

Non-limiting examples of hexafunctional aromatic compounds useful for method (Ml) of the present invention are :

The most preferred polyfunctional aromatic compound for use in accordance with the method (Ml) is 2,4,4-trifluorodiphenylketone.

The dinucleophile of method (Ml) acts typically as linking agent (comonomer) for the polymerization of the polyfunctional aromatic compound having at least three functional groups or the copolymerization thereof with the difunctional aromatic. It is advantageously a dihydric polynuclear phenol, preferably a dihydroxy aromatic compound.

Non-limiting examples of dinucleophiles suitable for use in method (Ml) include :

wherein G is independently selected from a carbonyl group (C=O), an oxygen atom (-O-) or a sulfur atom (-S-) ; in particular, in the last two depicted formulae, all the G may be oxygen atoms.

The most two preferred dinucleophiles for use in method (Ml) are hydroquinone and 4,4'-dihydroxybenzophenone.

In accordance with method (Ml), the polyfunctional aromatic compound having at least three functional groups as set forth above is optionally and preferably copolymerized with a difunctional aromatic compound, wherein the functional groups are advantageously halogens, more preferably Cl and/or F, and still more preferably F.

The difunctional aromatic compound of method (Ml) has advantageously electron withdrawing properties and can include, but is not limited to a dihalobenzenoid compound. The difunctional aromatic compound of method (Ml) is preferably a difluorobenzenoid compound.

Non-limiting examples of difunctional aromatic compounds useful in the method (Ml) of the present invention are:

and the same compounds as shown above but wherein each SO ₂ group (when present) is replaced by a C=O group and each chlorine group (when present) is replaced by a fluorine group.

In accordance with method (Ml), the most preferred difunctional aromatic for copolymerization with 2,4,4-trifluorodiphenylketone is 4,4'- difluorobenzophenone.

By combining the polyfunctional aromatic having at least three functional groups, or its combination with the difunctional aromatic, with an excess of the dinucleophile, generally a diol linking agent, the polymerization reaction is controlled so as to limit the molecular weight of the resulting polymer or copolymer and thus preserve the workability of the material prior to curing. An excess is defined in terms of the total number of hydroxyl groups of the linking agent relative to the total number of functional groups in the poly- and difunctional aromatics, wherein the former preferably exceeds the latter, preferably by at least 1 % or more preferably, by at least 10%.

Generally, the nucleophilic polymerization in accordance with the method (Ml) allows the preparation of polymers according to the following scheme: Equation I:

-W)* + Q(Nu) ₃ * ^■ Base - Optionally Af ¹ ^Y) ₂ + Opjmnatiy Af- halogen

PQIV mar the functional groups Y can be the same or different, wherein at least one of the X's and one of the Y's comprise a halogen and the remaining X's and Y's are independently selected from the list of halogens and nucleophiles,

said nucleophiles being selected independently from the list of the below nucleophiles (shown in their protonated form) :

the groups — Nu are selected independently from the list of nucleophiles (shown in their protonated form):

the base is any base strong enough to deprotonate the nucleophile or to accept the acid liberated on reaction. It will be recognized by one skilled in the art that some of the nucleophiles shown do not need to be deprotonated to react with an activated aryl halide (e.g. — NH ₂ ) while others do (e.g. — OH, — SH, — NRH where R is alkyl, aryl, alkyl ketone or aryl ketone and phthalimide). The term nucleophile is used herein to refer to both the protonated and deprotonated forms. Q is any divalent moiety and may be aliphatic or aromatic and may contain heteroatoms and additional substituents, for example to aid in solubility or processibility.

Typically, the dinucleophile and base are allowed to react first, with removal of water as necessary (for example, azeotropic distillation), After this step, the dinucleophile may be monoanion or a dianion (e.g. a double alkali metal salt), depending on the relative strength of the base and first and second pKa' s of the dinucleophile. In either case it is preferred to have at least one equivalent of base for each halogen group present so that as the reaction proceeds there is enough base to form the anion of each nucleophile group.

It is preferred that the independently selected functional groups X and Y (Equation I) consist of halogen or hydroxy groups, where the moles of hydroxy groups may be the same or in excess of the moles of the halogen groups. The excess is preferably about 1 mol %, more preferably 2 mol %, yet more preferably 3 mol %, even more preferably 5 mol %, and most preferably 6-12 mol %. A large excess may be applied as needed to control molecular weight. Optionally, X comprises all halogen groups and Y, all hydroxy groups.

As a further option, a monohalo monomer may be included to control molecular weight. Said monohalo monomer acts typically as an endcapping agent. Very often, essentially no monohalo monomer, and more generally no endcapping agent, is used during the nucleophilic polymerization in accordance with method (Ml) ; often, the method (Ml) for preparing a cross-linkable poly(aryl ether ketone) is one comprising the nucleophilic polymerization of the polyfunctional aromatic compound as above defined with the dinucleophile as above defined, in the total absence of a monohalo monomer, and more generally of an endcapping agent. Ar, Ar' and Ar" are aromatic rings bearing one or more substituents having electron withdrawing properties. Such substituents can include ketone, sulfone, phosphine oxide, sulfoxide, cyano, fluoro, trifluoromethyl, nitro, azo groups and the like. Ar, Ar' and Ar" may be multiring or fused ring groups including heterocyclic rings. Halo is F, Cl, Br, I, R is alkyl, aryl, alkylester, arylester, amide, fluoroalkyl, fluoroaryl, alkylketone or arylketone. In its most general form, Q can be represented as:

where m is 0 to 4 and the R _(m) are independently selected from alkoxy, aryloxy, alkyl, aryl, alkylester, arylester, amide, fluoroalkyl, fluoroaryl, polyalkalene oxy. Any two adjacent R _(m) may be bridging to form cyclic or heterocyclic units. Z is independently selected from the group consisting of nil, -0-, -S-, -NR- and - CRiR ₂ -, and Ri and R ₂ are independently selected from alkoxy, aryloxy, alkyl, aryl, alkylester, arylester, amide, fluoroalkyl, fluoroaryl, alkylketone, or arylketone. Reaction of the diol linking agent with K ₂ CO ₃ or Na ₂ CO ₃ or an appropriate base as is well known in the art ; it turns the diol into the corresponding double alkali metal salt which allows the polymerization reaction to proceed to completion.

The resulting cross-linkable poly(aryl ether ketone) is stable, soluble in a variety of organic solvents and workable so as to readily facilitate molding, compositing, its use as an adhesive, coating or blending component.

Subsequent curing of the cross-linkable poly(aryl ether ketone) takes usually place at an elevated temperature, typically greater than about 25O ⁰ C, preferably 300 ⁰ C or more preferably 34O ⁰ C.

Said curing is also known as cross-linking, as a cross-linked poly(aryl ether ketone) is obtained. This one often has a very high glass transition temperature. In accordance with method (Ml), the curing is generally carried out in the presence of a curing agent and/or a catalyst (or catalytic system). Examples of suitable curing agents include organic peroxides. The curing may also be advantageously carried out in the presence of a catalyst (or catalytic system) such as activated zinc dust (e.g. by HCl treatement), preferably in the presence of bis- triphenylphosphine nickel dichloride and triphenylphosphine. Method (M2) to prepare the cross-linkable polyfaryl ether ketone).

The method (M2) for preparing a cross-linkable poly(aryl ether ketone) comprises a nucleophilic polymerization of at least two different monomers : i) at least one polyfunctional aromatic compound (m21) having at least three functional groups selected from halogens and hydroxyls groups, with ii) at least one difunctional aromatic compound (m22) having two functional groups, said functional groups being selected from halogen and hydroxyl groups, wherein the total number of moles of hydroxyls groups (-OH) present in the monomers (m21) and (m22) divided by the total number of moles of halogens groups (-X) present in the monomers (m21) and (m22) is above 1.00 :

OH/X ratio > 1.00 That the OH/X ratio is > 1.00 is a key feature of the method (M2). Indeed, when said ratio was above 1.00, the curing of the so-obtained cross-linkable poly(aryl ether ketone) can surprisingly be easily carried out in the absence of any curing agent and in the absence of any catalyst (or catalytic system), as usually required for curing the cross-linkable poly(aryl ether ketone) prepared by method (Ml).

Thus, in a preferred embodiment of method (M2), the curing of the so- obtained cross-linkable poly(aryl ether ketone) is carried out in such conditions, i.e. absent any curing agent and any catalyst or catalytic system, and, very preferably, it is carried out under the sole action of heat (purely thermal curing). Then, the temperature at which the curing is carried out is typically greater than

about 25O ⁰ C, preferably greater than 300 ⁰ C or more preferably greater than 34O ⁰ C.

The OH/X ratio may be above 1.01, 1.02, 1.03, 1.04, 1.06, 1.08, 1.10, 1.15, 1.20, 1.35, 1.5, 2 or more. It is preferably above 1.01, more preferably above 1.02, and still more preferably above 1.04.

In certain embodiments of method (M2), the OH/X ratio is below 10, 5, 2, 1.5, 1.35, 1.20, 1.15 or 1.10.

Good results are obtained notably when the OH/X ratio ranges from 1.01 to 1.10. Likewise the method (Ml), the method (M2) allows the preparation of a cross-linkable poly(aryl ether ketone) which is capable of undergoing curing reactions (cross-linking). The cross-linkable poly(aryl ether ketone) is advantageously prepared in a single step utilizing mostly commercially available starting materials. In a preferred embodiment (M2*) of the method (M2), said method (M2) for preparing a cross-linkable poly(aryl ether ketone) comprises a nucleophilic polymerization of i) at least one polyfunctional aromatic compound having at least three reactive groups selected from hydroxyl and halogen groups ; with ii) at least one difunctional aromatic compound wherein the two functional groups comprises a halogen and optionally iii) at least one dinucleophile.

The method (M2*) requires the polymerization of a polyfunctional aromatic having at least three functional groups or, preferably, the copolymerization thereof with a dinucleophile using a difunctional aromatic compound wherein the two functional groups comprises a halogen (hereinafter, "the dihalocompound of method (M2*)"), which acts as a linking agent. By selecting the proportions of each of the components, a stable polymer or copolymer is provided having the desired degree of workability prior to curing and which can subsequently cured into a thermally stable material having a high glass transition temperature. The polyfunctional aromatic compound of method (M2), in particular the polyfunctional aromatic compound of method (M2*), is advantageously free of any cyclic heteroatom.

The polyfunctional aromatic compound of method (M2), in particular the polyfunctional aromatic compound of method (M2*), may have electron withdrawing properties and can thus include, but is not limited to, a sulfone, carbonyl or phosphine oxide group. Alternatively, it may be free of any group

having electro withdrawing properties (e.g. trihydroxybiphenyls). It often includes at least one carbonyl group.

In accordance with method (M2), in particular in accordance with method (M2*), the functional groups of the polyfunctional aromatic compound may comprise a combination of two halogens and at least one hydroxyl group, or preferably one halogen and at least two hydroxyl groups, or more preferably at least three halogens. Still more preferably, all the functional groups of polyfunctional aromatic compound of method (M2), in particular all the functional groups of the polyfunctional aromatic compound of method (M2*), are hydroxyl groups. The halogen(s), when however present, is (are) preferably fluorine.

The polyfunctional aromatic compound of method (M2), in particular the polyfunctional aromatic compound of method (M2*), is advanatgeously selected from the group consisting of trihydroxy aromatic compounds, tetrahydroxy aromatic compounds, pentahydroxy aromatic compounds, and hexahydroxy aromatic compounds.

Compounds which are particulary useful for use as the polyfunctional aromatic compound in accordance with method (M2), in particular with method

(M2*) include :

D

C« x— D

wherein, in the above formulae, the B are independently selected from C=O and SO ₂ , and are preferably C=O , and each D represents a hydroxyl group.

Out of these trihydroxy aromatic compounds,

where B is C=O and D is OH is the most preferred.

Hexahydroxy compounds could also be useful for use as the polyfunctional aromatic compound in accordance with method (M2), in particular with method (M2*) ; examples of such hydroxy compounds are could be of the same formulae as the hexafunctional aromatic compounds useful for method (Ml), except that in said hexafunctional aromatic compounds, each halogen (chlorine or fluorine) is replaced by a hydroxyl group.

The dihalocompound of method (M2*) acts typically as linking agent (comonomer) for the polymerization of the polyfunctional aromatic compound

having at least three functional groups or the copolymerization thereof with the dinucleophile.

Compounds which are particulary useful for use as as the dihalocompound of method (M2*) are selected from the group consisting of :

and its homologous wherein the chlorine atoms are replaced by fluorine atoms,

-- G -„

A-

, and

_N - G. _^ ,

A

wherein, in the above formulae, the A are independently chosen from fluorine and chlorine, and the G are independently chose, from C=O and SO ₂ ; preferably, the A are fluorine ; also preferably, the G are C=O.

The most preferred compound for use as as the dihalocompound of method (M2*) is 4,4'-difluorobenzophenone.

In accordance with method (M2*), the polyfunctional aromatic compound having at least three functional groups as set forth above is optionally and preferably copolymerized with a dinucleophile.

The dinucleophile of method (M2*) complies advantageously with the same features and preferences as the dinucleophile of method (Ml). Thus, in particular, the most two preferred dinucleophiles for use in method (Ml) are hydroquinone and 4,4'-dihydroxybenzophenone.

As a further option, a monohydroxy monomer may be included to control molecular weight. Said monohydroxy monomer acts typically as an endcapping agent. Very often, essentially no monohydroxy monomer, and more generally no endcapping agent, is used during the nucleophilic polymerization in accordance with method (M2*) ; often, the method (M2*) for preparing a cross-linkable poly(aryl ether ketone) is one comprising the nucleophilic polymerization of the polyfunctional aromatic compound as above defined with the dihalocompound as

above defined, in the total absence of a monohydroxy monomer, and more generally of an endcapping agent.

In accordance with method (M2), the resulting cross-linkable poly(aryl ether ketone) is stable, soluble in a variety of organic solvents and workable so as to readily facilitate molding, compositing, its use as an adhesive, coating or blending component. Method (M3) to prepare the cross-linkable polyfaryl ether ketone).

The method (M3) for preparing a cross-linkable poly(aryl ether ketone) comprises an electrophilic polymerization of at least one monomer (m33), said monomer (m33) being chosen from the compounds of general formula

wherein n is an integer ranging from to 0 to 3 ; n is usually equal to 0 or 1 ; and n is preferably equal to 1.

Thus, when n = 1, the metod (M3) comprises an electrophilic polymerization of phenoxy phenoxy benzoic acid (PPBA). For convenience, the chemical formula of PPBA is reproduced below:

(XXIII)

Optionally, one or more monomers other than the monomer (m33) can be electrophilically polymerized together with the monomer (m33). As examples of such other monomers, it can be notably cited the compounds of general formula

wherein p is an integer ranging from to O to 3, p being usually equal to

0 or 1, and p being preferably equal to 1 ; and the compounds of general formula

wherein q is an integer ranging from to 0 to 3, q being usually equal to

0 or 1, and q being preferably equal to 1.

Among these ones, the compounds of general formula (XXIV) are generally preferred over the compounds of general formula (XXV), notably because their additional incorporation in the cross-linkable poly(aryl ether ketone) results in the presence of additional carboxyl groups which can be easily reacted under the sole action of heat, as the hydroxyl groups of the cross-linkable poly(aryl ether ketone) in accordance with method (M2).

When the method (M3) comprises an electrophilic polymerization of at least one monomer (m33) and at least one monomer of general formula (XXV), desirably no other monomer is copolymerized. Then, the molar amount of the comonomer of general formula (XXV) based on total number of moles of the monomer (m33) and the comonomer of general formula (XXV), ranges advantageously with certain limits : it is preferably from 0.005 to 0.10, more preferably from 0.01 to 0.08, and can be notably of at least 0.02 or 0.03 and of at most 0.06 or 0.05.

In a particular embodiment (M3*) of the method (M3), this one comprises an electrophilic polymerization of at least one monomer (m33) essentially in the absence of any other monomer, and preferably in the total absence of any other monomer. In said particular embodiment (M3*), the method comprises an electrophilic polymerization of one and only one monomer (m33) essentially in the absence of any other monomer, and preferably in the total absence of any other monomer. Then, when electrophilically polymerized, the monomer (m33) undergoes exclusively a self-condensation reaction. The method (M3*) is especially easy for use. Likewise the method (M3), it allows the production of a poly(aryl ether ketone), in particular a poly (ether ether ketone) (PEEK), which is outstandingly thermally stable and melt processible under normal processing conditions, and which can further be quite easily cross- linked under standard curing conditions. Thus, while the curing of the so-

obtained cross-linkable poly(aryl ether ketone) of method (M3), in particular of method (M3*), can be carried out in the presence of a curing agent and/or in the presence of a catalyst (or catalytic system) such as those previously mentioned as useful for the cross-linkable poly(aryl ether ketone) prepared by method (Ml), the curing of the cross-linkable poly(aryl ether ketone) of method (M3), in particular of method (M3*), can also and, for commodity reasons, is preferably carried out absent any curing agent and absent any catalyst or catalytic system, and, very preferably, it is carried out under the sole action of heat (purely thermal curing). Then, the temperature at which the curing is carried out is typically greater than about 25O ⁰ C, preferably greater than 300 ⁰ C or more preferably greater than 34O ⁰ C.

Without being bound by any theory, this is likely made possible notably because, surprisingly, the crosslinkable poly(aryl ether ketone) of method (M3), in particular of method (M3*), although being generally mainly linear, does well contain branch points which include an -OH group, typically as shown in figure 1. Even if no hydroxy group would be present in the cross-linkable poly(aryl ether ketone) of method (M3) due to branch points, such tertiary hydroxyl groups would be usually generated due to the presence of traces of humidity. The presence of hydroxyl groups in the cross-linkable poly(aryl ether ketone) of method (M3) is substantiated by the fact that said poly(aryl ether ketone) exhibits a high AS value in UV spectra. Indeed, the higher the AS value, the higher the number of hydroxyl groups present on the polymer chain. These - OH groups help greatly in cross-linking the PEEK efficiently under curing conditions. The AS value of the cross-linkable poly(aryl ether ketone) of method (M3), especially of the cross-linkable poly(ether ether ketone) of method (M3*), may be well above 6500 ; it can be higher than 800, 1,000 or even 1,200. AS value measurement. While direct measurement of branches on polymeric chains is desirable but extremely difficult and costly, indirect ways have been found which allow the determination of the presence of branching and in particular of long chain branches. One outcome of branch structure is that a tertiary carbocation is generated in highly acidic solution when PAEK is produced using Phenoxy Phenoxy Benzoic acid in MSA as described earlier. The color generated can be readily measured using UV spectroscopy and Absorption (AS) value can be determined. AS value is a good quantitative, though relative, indicator of Hydroxy group at branch points present on the polymeric chains.

Similarly, apparent melt viscosity as measured at very low shear rates using capillary rheometers increases with the presence of long chain branches, due to entanglement effects. Thus, higher the melt viscosity, higher the number of long chain branches present on the main chains. In addition, the cross-linkable poly(aryl ether ketone) of method (M3) includes also polymer chains having unreacted carboxyl end groups, originating from the carboxyl group of the monomer (m33).

As a further option, an endcapping agent might be added to control molecular weight, insofar as it does not affect substantially the cross-linkability of the cross-linkable poly(aryl ether ketone) by desactiving its reactive end groups. Non limitative examples of endcapping agents are aromatic compounds like benzene, toluene, xylene, phenol, anisole, diphenyl Ether or any of then- stable derivatives. Howver, since endcapping agent are generally detrimental to the cross-linkability of the cross-linkable poly(aryl ether ketone), essentially no endcapping agent is generally used during the electrophilic polymerization in accordance with method (M3), especially (M3*). Preferably, the method (M3*), especially (M3*) for preparing a cross-linkable poly(aryl ether ketone) is one comprising the electrophilic polymerization of at least one monomer (m33) as above defined (e.g. PPBA) in the total absence of an endcapping agent. The solvent used in method (M3) is preferably an alkane sulfonic acid including haloalkane sulfonic acid, preferably methane sulfonic acid (MSA), trifluoro or trichloro methane sulfonic acid.

A condensing agent is also advantageously used in the electrophilic synthesis of PEEK. Good results were obtained when thionyl chloride, phosphorous trichloride, phosphorous pentachloride or phosphorous pentoxide, methane sulfonic anhydride or their mixtures were used.

This method may also optionally use a diluent. The diluent is, for example, a non-polar aprotic solvent such as methylene chloride, ethylene dichloride, or sulfolane, or their mixtures or any of the polar organic compounds remaining inert in this system.

The reaction via electrophilic route takes place at temperatures in the range of 40 to 16O ⁰ C, followed by precipitation of the said poly(ether ether ketone) in water after it has achieved the desired inherent viscosity (Inh.V.) and after the removal of the acid residues with treatments with water and later with organic solvent like DMAc or DMF or with bicarbonate solution, filtering and drying it to give the cross-linkable poly(ether ether ketone), such as the one described in

U. S. Pat. 6,566,484, the whole content of which is also herein incorporated by reference.

The alkane sulfonic acid mixture with its anhydride was found to be a solvent as well as a powerful catalyst for polymerization, of phenoxy phenoxy benzoic acid (PPBA) to give PEEK. It was also found that in MSA-MSAN system, the methane sulfonic acid anhydride (MSAN), gets easily reconverted into MSA after reaction work-up in water, so that recycling is possible and waste generation is minimal, MSA being recoverable and recyclable. Additionally, the MSAN need not be prepared separately and added during the reaction, but can also be prepared in-situ. When the reaction mass is added into water during the work-up of the reaction, the acid remains dissolved in water and the polymer easily precipitates out. The polymer is isolated by filtration, and is washed and dried. Any unreacted anhydride present in the reaction mass gets reconverted into the acid by reaction with water during the work-up. The resultant acid and water mixture can be easily separated by fractional distillation and both the acid and water can be recycled for the next batch.

In MSA-P ₂ O ₅ system, similarly, MSA and H ₃ PO ₄ are formed on precipitation of PEEK in water, from which MSA can be separated and reused. Thus, a significant advantage of this method is the ease of work-up and isolation of polymer due to the use of aqueous system for precipitation of PEEK. Further purification of PEEK is required to remove traces of acid, which can be accomplished by washing with hot water containing alkali and/or refluxing in an organic solvent like DMF, DMAc, etc and subsequently refluxing in water again to remove last traces of salt and alkali and organic solvent. Generation of MSAN is readily carried out with any of the condensing agents, thionyl chloride (SOCI ₂ ) or phosphorous pentoxide are the preferred reagents, due again to the ease of operation and feasibility of using the byproducts, with minimum waste generation.

SOCl ₂ reacts with MSA to give flue gasses SO ₂ and HCl, which can be reacted back to give SOCI ₂ , and recycled, (Geiko V. L, Gladushko et. al. Khim. Khim. Tecknol. 1985, 28(5) - 4 (Russ)). With P ₂ O ₅ , similar treatment yields H ₃ PO ₄ , a useful acid, which also can be separated from its mixture with MSA by extraction with suitable solvents or by fractional distillation of MSA and used as such. The method (M3) makes it possible to prepare PEEK and other poly(aryl ether ketone)s electrophilically using homogenous solutions. In this method, rate

of polymerization reaction and ultimate molecular weights can also be readily controlled by a proper choice of reaction temperature, monomer concentration, and the quantity of anhydride employed. Thus, the kinetics of polymerization is easily controlled. Another advantage is the use of an acid monomer as the precursor.

Since preferred polymerization temperatures are low to moderate, preferably in the range of 60-130 ⁰ C only, towards the end, the reaction mass viscosity increases and it makes efficient stirring difficult.

Addition of diluents, like CH ₂ Cl ₂ or CH ₂ Cl-CH ₂ Cl or toluene, helps advantageously in keeping the solution stirrable and improves mixing. Another advantage derived by the addition of a diluent, which can be low boiling and immiscible with water, is that on precipitation in hot water, it simply boils off and thus gets readily separated. Another advantage of adding a diluent is that the precipitating PEEK is obtained in this case as fine granules or powder. Without such a diluent, lumps or thick fibres are obtained requiring further size reduction. Yet, another advantage of using the diluent is that the PEEK obtained as powder contains less than 10% MSA entrapped in it, while the lumpy or fibrous PEEK contains as much as 15-25% MSA entrapped, requiring more exhaustive post- polymerization treatments. After separation from the reaction mass by precipitation in water, the polymer is filtered and washed conveniently free of MSA and H ₃ PO ₄ , if any, as shown in the examples. PEEK is subsequently treated in refluxed water, followed by refluxing in alkaline solution. Alternately, an organic base like dimethyl formamide (DMF) or dimethyl acetamide (DMAc), etc. can also be used.

Preferably, PEEK so produced has to be made completely free of the solvent, as even small quantities of the solvent left behind has very deleterious effect on the processability of PEEK at high temperatures.

In certain embodiments, the method (M3) allows the production of poly(ether ether ketone) (PEEK), which is thermally stable and melt processible under normal processing conditions but cross-linkable under curing conditions, and involves polymerising phenoxy phenoxy benzoic acid (PPBA) using alkyl sulfonic acid and a condensing agent with or without a diluent at 40- 16O ⁰ C, thereafter, separating PEEK from the reaction mixture by precipitation in water and giving further water treatments for purification. Further, PEEK powder

may be treated with organic solvent with or without formic acid to improve the colour.

Method (M4) to prepare the cross-linkable polyfaryl ether ketone).

The cross-linkable poly(aryl ether ketone) can also be made by a method comprising an electrophilic polymerization, of at least one monomer (m31) and at least one monomer (m32).

The monomers (m31) and (m32) undergo generally a condensation reaction with each other.

Possibly, the monomer (m31) is chosen from compounds of general formula

wherein p is an integer ranging from to 0 to 3, p being usually equal to

0 or 1, and p being preferably equal to 1 and the monomer (m32) is chosen from compounds of general formula

wherein q is an integer ranging from to 0 to 3, q being usually equal to 0 or 1, and q being preferably equal to 1.

The two monomers (m31) and (m32) may also be respectively dicarboxy benzophenone and diphenyl ether. In general, (m31) is an aromatic dicarboxy lie acid, and (m32) is a dibenzenoid compound.

A MSA-based system or an A1C13 /EDC system may be used.

Advantageously, the dicarboxy lie acid monomer (m31) is in molar excess of higher than 0.5 mole % when compared to the dibenzenoid compound (m32).

Optionally, this method (M4) allows also for the presence of a third aromatic monomer with at least three carboxyl groups. The articles and parts of shaped articles in accordance with the present invention.

The present invention relates also to cross-linked poly(aryl ether ketone) shaped articles, or part of shaped articles, which are essentially at most two- dimensional. These include essentially one-dimensional shaped articles like

filaments or to essentially two-dimensional shaped articles like films, sheets and slabs. It relates also to performing methods of making said shaped articles, and to end-uses of said shaped articles.

Preferably, the essentially at most two dimensional article of the present invention is selected from a film, a fiber, a sheet, a slab or a hollow body. More preferably, it is a film.

Preferably, said article comprises cross-linked poly(ether ether ketone). Preferably, said article comprises cross-linked poly(ether ketone). Preferably, said article comprises cross-linked poly(ether ketone ketone). More preferably, said article comprises cross-linked poly(ether ether ketone).

From a practical point of view, any shaped article is three-dimensional, and can thus be characterized notably by three characteristic dimensions ("length", "width" and "height"). However, some shaped articles are such that one or two of their characteristic dimensions is (are) considerably lower than respectively the other two ones or the third one. Here and wherever else used in the present description, the terms "considerably lower" should generally be understood as "more than 5 times lower" and preferably as "more than 10 times lower", unless they characterize a "two-dimensional thickness" as defined hereafter in the description.

Precisely, for the purpose of the present invention an essentially two- dimensional shaped article is intended to denote a shaped article of which one of its characteristic dimensions ("thickness-height") is considerably lower than its other two ones ("width" and "length"), while an essentially one-dimensional shaped article is intended to denote a shaped article of which two out of its characteristic dimensions ("thickness- width" and "thickness-height") are considerably lower than its third one ("length"). Otherwise said, from a mathematic point of view, essentially two-dimensional articles have essentially the appearance of a geometric surface, while essentially one-dimensional articles have essentially the appearance of a geometric line. Thus, an essentially two- dimensional article can be viewed as a surface (with a certain length and a certain width) differing from a geometric surface in that it has a certain non-zero thickness (typically in a direction perpendicular to the surface), said non-zero thickness being however considerably lower than the square root of the surface area developed by the surface itself and, more precisely, said non-zero thickness being considerably lower than both the length and the width of the surface itself ;

an essentially one-dimensional article can be viewed as a line (of a certain length) differing from a geometric line, essentially in that it has a non-zero "two- dimensional thickness" (typically in a plane perpendicular to the line, with a certain non-zero thickness-width and a certain non-zero thickness-height as characteristic dimensions), said non-zero two-dimensional thickness being however considerably lower (here specifically, the terms "considerably lower", which characterize a two-dimensional thickness, should generally be understood as "more than 25 times lower" and preferably as "more than 100 times lower") than the square of the length of the line itself, more precisely, said non-zero thickness- width and said non-zero thickness-height being both considerably lower than the length of the line itself. The geometric surface can be curved or plane, twisted or untwisted ; the geometric line can be a straight line or a curved line.

Essentially zero-dimensional articles i.e. articles having essentially the appearance of a geometric point (sometimes also referred to as "material point"), with essentially no length, no width and no height, like powdery spherical particles of polymer or powdery spherical inorganic particles coated with a polymer (with a typical diameter of a few microns), are not shaped articles within the meaning of the present invention. Thus, within the meaning of the present invention, an essentially at most two-dimensional shaped article can be either an essentially two-dimensional shaped article or an essentially one- dimensional shaped article.

The thickness of a shaped article of a regular or irregular volume is preferably defined as : t = Jv τ(x,y,z) dx dy dz / V, wherein x, y and z are the coordinates of an elementary volume dV (dV being equal to dx times dy times dz) of the shaped article of overall plain volume V, and τ is the local thickness.

The local thickness τ, associated to a material point of coordinates (x,y,z), is defined as the length of the shortest straight line D including the material point of concern, which goes right through the shaped article (i.e. which goes from the material point where D enters the shaped article to the material point where D exits the shaped article).

Shaped article (A) has a thickness t advantageously lower than 100 mm. A first preferred shaped article (A) is essentially two-dimensional [shaped article (Al)].

The thickness t of shaped article (Al) complies preferably with the relationship : t < (V/k ² ) ^1/3 [ which is equivalent to V > (k.t) . (k.t) . t ] (rel-1) wherein V is the overall plain volume of the shaped article and k is equal to 10, t is expressed in mm and V is expressed in mm ³ .

The thickness t of shaped article (Al) complies very preferably with above relationship (rel-1), except k is now equal to 100.

In addition, the thickness t of shaped article (Al) complies preferably with the relationship : t < (S/2) ^1/2 / k [ which is equivalent to S > 2 . (k.t) . (k.t) ] (rel-2) wherein S is the overall surface area developed by the shaped article, k is equal to 10, t is expressed in mm and S is expressed in mm ² .

The thickness t of shaped article (Al) complies very preferably with above relationship (rel-2), except k is now equal to 100. In a first preferred variation of shaped article (Al), shaped article (Al) is chosen from articles having a thickness lower than 500 μm [shaped article (Al-I)]. Shaped article (Al-I) is commonly referred to as a film.

Shaped article (Al-I) has a thickness of preferably less than 250 μm, more preferably less than 150 μm. Shaped article (Al-I) has a thickness of preferably more than 5 μm, more preferably more than 50 μm.

Shaped article (Al-I) complies preferably with relationship (rel-1) in which k has been changed to 1000. Very preferably, it complies with relationship (rel-1) in which k has been changed to 10000. Shaped article (Al-I) is preferably flexible. It is sometimes very preferred that article (Al-I) can be flexed in such a way that it can get the appearance of a parallelepiped rectangle-like volume the thickness of which is considerably lower than its length and its width ; roughly speaking, it looks then like a "plane with an extremely low thickness". Shaped article (Al-I) can be an uncoated film.

Alternatively, shaped article (Al-I) can be a film coated on an essentially two- or on a three-dimensional substrate. The essentially two- or the three- dimensional substrate can be notably a fabrics, a polymeric film free of polymer (P), a sheet of paper, a wood or a metal component. An embodiment of article (Al-I) is one wherein the substrate is a metal component.

Another embodiment of article (Al-I) is one wherein the substrate differs from a metal component.

In a second preferred variation of shaped article (Al), shaped article (Al) is chosen from shaped articles having a thickness from 500 μm to 5000 μm [shaped article (Al-2)].

Shaped article (Al-2) has preferably the appearance of a parallelepiped rectangle-like volume the thickness of which is considerably lower than its length and its width ; roughly speaking, it looks then like a "plane with a very low thickness". Then, shaped article (Al-2) is commonly referred to as a sheet. In a third preferred variation of shaped article (Al), shaped article (Al) is chosen from shaped articles having a thickness above 5000 μm [shaped article (Al-3)].

Shaped article (Al-3) has preferably the appearance of a parallelepiped rectangle-like volume the thickness of which is considerably lower than its length and its width ; roughly speaking, it looks then like a "plane with a low thickness". Then, shaped article (Al-3) is commonly referred to as a slab.

Shaped article (Al-3) is advantageously rigid.

In a fourth preferred variation of shaped article (Al), shaped article (Al) is a hollow body [shaped article (A 1-4)]. The thickness of the walls of shaped article (A 1-4) is advantageously equal to the thickness t of shaped article (Al -4).

Shaped article (Al -4) has a thickness t of preferably at least 250 μm, more preferably at least 500 μm.

Shaped article (Al-4) has a thickness t of preferably at most 5000 μm, more preferably at most 2500 μm.

A second preferred shaped article (A) is essentially one-dimensional [shaped article (A2)].

Shaped article (A2) has a thickness t which is preferably lower than 10 mm, more preferably less than 250 μm, still more preferably less than 50 μm, and the most preferably less than 10 μm.

The thickness t of shaped article (A2) complies preferably with the relationship : t < (V/k' ) ^1/3 [which is equivalent to V > (k' .t) . t . t ] (rel-3) wherein k' is equal to 10, V as above defined, t is expressed in mm and V is expressed in mm ³ .

The thickness t of shaped article (A2) complies very preferably with above relationship (rel-3), except k' is now equal to 100.

The thickness t of shaped article (A2) complies still more preferably with above relationship (rel-3), except k' is now equal to 1000.

The thickness t of shaped article (A2) complies the most preferably with above relationship (rel-3), except k' is now equal to 10000. In addition, the thickness of shaped article (A2) complies preferably with the relationship : t < (S/k') ^1/2 / 2 [which is equivalent to S > 4 . (k' .t) . t ] (rel-4)

S as above defined, k'is equal to 10, t is expressed in mm and S is expressed in mm ² . The thickness t of shaped article (A2) complies very preferably with above relationship (rel-4), except k' is now equal to 100.

The thickness t of shaped article (A2) complies still more preferably with above relationship (rel-4), except k' is now equal to 1000.

The thickness t of shaped article (A2) complies the most preferably with above relationship (rel-4), except k' is now equal to 10000.

In a first preferred variation of shaped article (A2), shaped article (A2) has the appearance of a cylinder-like plain volume the diameter of which is considerably lower than its length ; roughly speaking, it looks then like a "straight line with an extremely low diameter" [shaped article (A2-1)]. Shaped article (A2-1) is commonly referred to as a fiber.

For certain variations of shaped article (A2), in particular when shaped article (A2) is a filament, good results can be obtained notably when shaped article (A2) consists essentially of, or even consists of, polymer composition (C).

In a second preferred variation of shaped article (A2), shaped article (A2) is a coating coated on an essentially one-dimensional substrate, like an inorganic fiber, a polymeric fiber free of polymer (P) or a metal [shaped article (A2-2)] . Shaped article (A2-2) has then preferably the appearance of a circular crown surrounding a cylinder-like plain volume composed by the essentially one- dimensional substrate, the thickness of the crown being considerably lower than the length and the diameter of the cylinder-like plain volume.

The thickness t of shaped article (A2-2) is still more preferably less than 50 μm, and the most preferably less than 10 μm. Besides, it is advantageously lower than the diameter of the essentially one-dimensional substrate.

Shaped article (A2-2) is advantageously few sensitive to interfacial segregation and delamination failure. In addition, it has advantageously a long-

term thermal stability. These good properties are usually achieved notably because of the high glass transition temperature of polymer (P).

The method for the preparation of an essentially at most two dimensional shaped article, or part of shaped article, comprising a material comprising a cross-linked poly(aryl ether ketone) according to the present invention comprises the steps of:

(a) heating a cross-linkable poly(aryl ether ketone) comprising chains which comprise more than two reactive end groups to a temperature of above its melting point, optionally in the presence of a curing agent and/or catalyst, wherein the reactive end groups are preferably selected from the group consisting of halogens, carboxyl and hydroxyl groups, and more preferably from the group consisting of carboxyl and hydroxyl groups, and wherein the crossinlinkable poly(aryl ether ketone) is preferably the poly(aryl ether ketone) prepared by any of the methods (Ml), (M2), (M3) and (M4) as previosuly detailed ;

(b) melting the cross-linkable poly(aryl ether ketone);

(c) forming said shaped article, or part of shaped article;

(d) maintaining it at a temperature of the melting point of the cross-linkable poly(aryl ether ketone) for a sufficient time in order to obtain said shaped article, or part of shaped article.

In a specific embodiment of said method for the preparation of essentially at most two dimensional articles, or part of shaped articles, comprising a material comprising a cross-linked poly(aryl ether ketone), the poly(aryl ether ketone) is poly(ether ether ketone). In such a case, in step (a) and (d), the temperature is of above 33O ⁰ C, preferably of above 34O ⁰ C and more preferably of above 345 ⁰ C. Following examples describes preparation of PEEK with long chain branching and the advantageous properties attain with it. They are meant to illustrate but not to limit the scope of work and claims.

EXAMPLES Different samples of cross-linkable poly(aryl ether ketone)s, esp. poly(ether ether ketone)s, useful for the manufacture of articles according to the present invention, esp. films of cross-linked poly(ether ether ketone) coated on a substrate, were prepared as detailed below.

Example 1. A cross-linkable poly(ether ether ketone) was synthesized by the electrophilic route, at a polymerization temperature of 12O ⁰ C. No end-capping

agent was used when polymerizing said reactive poly (ether ether ketone). Its method of manufacture is provided hereafter.

In a clean four neck, round bottom flask , 1706 g of methane sulfonic acid (MSA) was charged. It was heated to 55 C and to this , 71 g of a condensing agent, namely phosphorous pentoxide, was charged. The mixture was maintained at 60 C to form a homogenous solution. The temperature was then increased to 120 C and 153 g of 4,4'-phenoxy phenoxy benzoic acid (PPBA) was then added. The reaction temperature was maintained at 120 C for 10 minutes. After 10 minutes, the reaction mass was diluted by the addition of 2000 ml of ethylene dichloride (EDC). The reaction mass was then precipitated using 2000 ml water, which was kept at 75-80 ⁰ C to extract the acid from the polymer. The precipitated polymer was then repeatedly washed with water until the pH of the filtrate was neutral. The wet solids were then treated with 1600 g dimethyl acetamide (DMAc) at 145 ⁰ C for 5 h and again washed with water a few times to remove DMAc. They were subsequently dried in an air-circulating oven at 100 ⁰ C for 24 hours followed by drying at 180 ⁰ C for 8 h. Accordingly, a cross-linkable poly(ether ether ketone) (El) was recovered.

The inherent viscosity of the cross-linkable poly(ether ether ketone) (El) was 0.73 dl/g, as measured in a 0.5% solution in 98% concentrated sulfuric acid at 25 ^° C.

Absorbance value (AS value) of the cross-linkable poly(ether ether ketone) (El) was measured in a solution of composed of 10 mg of the final dry powder and 10 ml of dichloro acetic acid, and UV spectra were taken. The absorbance at 500-540 nm was measured and AS value was calculated as : Absorbance * 10000/wt. of the cross-linkable poly(ether ether ketone).

It was found to be 1365, as compared to 20 for a commercial sample (EO) of VICTREX ^® 450P poly(ether ether ketone), which was made by a nucleophilic process. Example 2 The same process as followed in example 1 was used except the polymerization was carried out at 12O ⁰ C for 20 minutes. Another cross-linkable poly(ether ether ketone) (E2) was also recovered in the form of a dry powder.

The inherent viscosity of the cross-linkable poly(ether ether ketone) (E2) was 0.94 dl/g, as measured in a 0.5% solution in 98% concentrated sulfuric acid at 25 C. Absorbance value (AS value), which was measured in the same conditions as above recited, was found to be 1094.

Example 3

The same process as followed in example 1 was used except the polymerization was carried out at 100 ⁰ C for 15 minutes. A third cross-linkable poly(ether ether ketone) (E3) was again recovered in the form of a dry powder. The inherent viscosity of the cross-linkable poly(ether ether ketone) (E3) was 0.73 dl/g, as measured in a 0.5% solution in 98% concentrated sulfuric acid at 25 C. Absorbance value (AS value), which was measured in the same conditions as above recited, was found to be 1337. Example 4 (comparative) In accordance with example 5, a first poly (ether ether ketone) (E4) commercially available from SOLVAY SPECIALITIES INDIA Private Ltd. as GATONE ^® 5300 was tested. GATONE ^® 5300 poly(ether ether ketone) was prepared by an electrophilic process in the presence of an endcapping agent.. The inherent viscosity of the poly(ether ether ketone) (E4) was 0.94 dl/g, as measured in a 0.5% solution in 98% concentrated sulfuric acid. Absorbance value (AS value), which was measured in the same conditions as above recited, was found to be 487. Example 5 (comparative)

In accordance with example 5, another poly(ether ether ketone) (E5) commercially available from SOLVAY SPECIALITIES INDIA Private Ltd. as GATONE ^® 5600 was tested. GATONE ^® 5600 poly(ether ether ketone) was also prepared by an electrophilic process in the presence of an endcapping agent.

The inherent viscosity of the poly(ether ether ketone) (E5) was 0.75 dl/g, as measured in a 0.5% solution in 98% concentrated sulfuric acid. Absorbance value (AS value), which was measured in the same conditions as above recited, was found to be 445. Example 6. Dissolution tests.

Samples (EO), (E2) and (E4) were taken for dissolution study.

Dry powders of said samples were ground to less than 100 μm, and then dispersed in NMP (30 % by volume), and then coated on a pre- weighted aluminum plate of dimension of 4" x 2". The plate was kept in an air circulating oven at 18O ⁰ C for 3 h to distill off NMP. The plate was then shifted to another oven kept at 380 C for 30 min. After cooling to ambient temperature, it was immersed in 98 % concentrated H ₂ SO ₄ for 7 days. The plate was then removed, washed with water, dried at 150 ⁰ C for 3 h, and then cooled and weighted to determine solubility of PEEK film. The loss in weight found was

1.36 % only for sample (E2) sample ; it was of 76 % for (E4) and the weight loss was complete (100 %) sample (EO).

The results are reported in table 1 below. Table 1. Dissolution test results, IV and AS values

Example 7. Powder coating.

Sample (El) and (E5) were used for the present powder coating study, as well as a powder of a poly(ether ether ketone) prepared by a nucleophilic process in the presence of an endcapping agent, commercially available from SOLVAY ADVANCED POLYMERS, L.L.C. as KETASPIRE ^® 880 P (sample EO*). Powder coating procedure. Dry powders of samples (El), (E5) and (EO*) were ground to less than 45 μm using a RETSCH grinder ZM 200, and then applied to aluminum panels having a size of 4" x 2", using a spray gun STATE FIELD- INTECH Model M-98, using filtered, compressed air at 20-30 psi (137-207 kPa) which pushed the powders out of the gun past the electrode, thereby giving a positive charge to the powders. The positively charged powder particles got attracted to the aluminum panels and were stuck on them. When the panels were completely covered, the ground powders were removed and the panels were kept in an oven at 380 ⁰ C for 30 minutes, so as to cure the powders. The panels were subsequently allowed to cool, and were tested according to various standard tests, as detailed below.

Mechanical and chemical properties tests.

Adhesion tests were run according to ASTM D3359 method - B. Scratch resistance tests were carried out using the BIS 101 procedure (Bureau of Indian Standard). The impact resistance tests were carried out according to ASTM D2794.

The chemical resistances of the samples were tested by the same dissolution test as explained in example 6.

The test results are provided in table 2 hereinafter. Table 2 Mechanical and chemical tests results

"Pass" means that cracks were not observed at embossed & dent area.

"Fail" = cracks were observed at embossed & dent area.

"> 5 Kg" means that the maximum loading limit of the instrument is 5.00 kg, and the needle of the instrument did not penetrate the polymer films to touch to metal base support.

As a conclusion from all these results, the Applicant prepared various cross-linkable poly(aryl ether ketone)s and shaped them into films of cross-

linked poly(aryl ether ketone)s, which exhibited superior impact resistance and chemical resistance test, when compared to the films made of various poly(aryl ether ketone)s prepared either by an electrophilic or a nucleophilic process in the presence of an endcapping agent. More generally, the Applicant is of the opinion that the cross-linkable poly(aryl ether ketone)s of the present invention are of important practical interest in many applications, including specialty coatings applications. Moreover, the Applicant has provided quite easy methods to prepare cross- linkable poly(aryl ether ketone)s and to shape them into films and coatings of cross-linked poly(aryl ether ketone)s.