The present invention relates to the manufacture and use of a reinforced profile and also to the reinforced profile itself.

PVC (polyvinyl chloride) window frames meet increasing consumer demand due to their low cost and their durability, their corrosion resistance requiring minimum maintenance and also their thermal insulation property, but they lack stiffness from a certain window size upwards.

Indeed, profiles made of a thermoplastic polymer are generally hollow in order to make them lighter and to create chambers that have a thermal insulation role. However, one problem inherent to thermoplastic polymers is their low elastic modulus and therefore their deformability under strain, especially when the spans between fixed points are large.

The lack of stiffness may be offset by reinforcing the frames with metal reinforcements and especially steel (DE 199 33 099) or aluminium

reinforcements. However, the use of metal reinforcements creates thermal bridges within the profiles of the frame, leading to significant heat losses through the increase in the thermal conductivity. Furthermore, the presence of these metal reinforcements complicates the end-of-life recycling of profiles.

In order to counteract this increase in the thermal conductivity, other solutions have been proposed that use, in particular, reinforcements (pultruded inserts) constituted by thermosetting resins with fibres, preferably continuous fibres, of glass, aramid or carbon (GB 2 144 472 or EP 0 441 449).

Nevertheless, the use of thermosetting resins with glass fibres is expensive. As regards the thermoplastic composites reinforced with cellulose fibres proposed by US 2004/062915, they are much more moisture-sensitive and therefore less durable.

Conventionally, window profiles made of a thermoplastic polymer (usually made of PVC) that are reinforced via the introduction, inside the profile, of a metal insert or a pultruded insert cannot be recycled or are difficult to recycle.

Another disadvantage of profiles made of a thermoplastic polymer that are reinforced by a pultruded insert is the fact that it is necessary, just as for metal reinforcements, to introduce the reinforcement manually, which increases their production cost. Patent EP 1 276 602 relates to joinery elements comprising a PVC profile reinforced with at least one reinforcing tape composed of fibres made of polyester, in particular made of PET (polyethylene terephthalate) or of PBT (polybutylene terephthalate) commingled with continuous glass fibres, the polymer fibres and glass fibres being positioned in a longitudinal and parallel manner. Tapes of fibres, or rovings, are heated in order to melt the polymer, pressed and finally embedded in the outer and opposite walls of the final PVC profile to provide sufficient stiffness and thus avoid the use of metal or pultruded inserts. Even though high mechanical properties are obtained and manual insertion of the metal or pultruded insert is avoided by virtue of the

manufacturing process, which uses reels that make it possible to unwind continuous yarns comprising continuous filaments of glass and of a

thermoplastic commingled together, this process has many disadvantages. One of the drawbacks of this system is combining, in the final product, two different thermoplastics that are incompatible in the melt state, a polyester such as PET or PBT on the one hand and PVC on the other hand, making not only the recycling of the profile difficult, but also making the recycling of the production scrap and also of the blanks into the profile production line impossible. Another drawback is the longitudinal brittleness of the reinforcements, which

preferentially break along the fibres during a multiaxial impact. Finally, another major drawback is the difficulty of calibrating the profile when it is cooling, considering that the PVC and the reinforcing tape have different thermal expansion coefficients.

Applications WO 99/22920 and WO 2005/038123 propose an improved process that consists in dispersing polymer powder in a network of fibres or filaments using an AC electric field and then in moulding the assembly by heating and pressing to form sheets. This process has the advantage of obtaining, at a lower cost, a more compact composite in which the fibres are well impregnated with polymer. However, the powders exemplified in these applications are either powders of crystalline polymers, which are easy to melt in the matrix, or powders of thermosetting resins that do not require mixing in order to be used. Again, thermosets are difficult, or even impossible, to recycle.

The applicant has developed PVC formulations that make it possible to produce, via this process, foils, sheets and tapes based on long PVC-impregnated fibres (see application WO 2008/065061), tapes which can advantageously replace tapes based on commingled continuous fibres. One object of the present invention is consequently to propose a variant of the process for manufacturing a profile that is reinforced without addition of metal or pultruded reinforcement and that is of low thermal conductivity.

In accordance with the invention, this objective is achieved by a process for manufacturing a reinforced profile, comprising at least the following steps :

(a) manufacturing at least one daughter tape containing a first thermoplastic polymer and long chopped fibres by

- dispersing the first thermoplastic polymer in powder form over the long chopped fibres positioned in an isotropic manner ;

- applying an AC electric field ; and

- heating under pressure ;

(b) optionally manufacturing a mother tape by superposing and welding at least two daughter tapes obtained in step (a) ; and

(c) manufacturing a reinforced profile using at least one daughter tape obtained in step (a) or at least one mother tape obtained in step (b) by extruding a molten second thermoplastic polymer on at least one face of the daughter tape or on at least one face of the mother tape.

The term "profile" is understood to mean any part produced by extrusion that is characterized by a constant cross section and a length that is several times greater than its width, excluding tubes, extruded foils, and sheets. Profiles are parts that are used, for example, in the production of window frames, doors, shutters, gates, coverings for walls and ceilings (panelling, boards), cable conduits and skirting boards.

The expression "thermoplastic polymer" is understood to mean all thermoplastic polymers (homopolymers and copolymers) and also blends thereof.

The expression "thermoplastic polymers" is understood to mean polymers that exist, at ambient temperature, below their glass transition temperature if they are amorphous or below their melting temperature if they are partially crystalline, and that are linear or branched, but not crosslinked. These polymers have the property of softening on heating and of hardening on cooling, without appreciable chemical change. Such a definition can be found, for example, in the encyclopaedia entitled "Polymer Science Dictionary", Second Edition,

Mark Alger, School of Polymer Technology, University of North London, London, UK, Chapman & Hall Edition, 1997. - A -

The thermoplastic polymers according to the invention may be amorphous or semi-crystalline.

Semi- crystalline thermoplastic polymers, within the meaning of the present invention, are thermoplastic polymers that exist, at ambient temperature, between their glass transition temperature and their melting temperature and are characterized by a certain degree of crystallinity. The semi- crystalline thermoplastic polymers according to the invention are generally characterized by a non-zero conventional crystallinity index.

Amorphous thermoplastic polymers, within the meaning of the present invention, are thermoplastic polymers that are characterized by a zero

conventional crystallinity index.

Any type of polymer or copolymer, the processing temperature of which is below its decomposition temperature, is suitable. Synthetic thermoplastics, the processing temperature of which is at most 10 ⁰ C below this decomposition temperature, are particularly well-suited for the process. In particular, halogenated polymers, polyolefms, polyesters, polyketones, polyamides and copolymers derived therefrom may be used. A blend of polymers or of copolymers may also be used.

The first thermoplastic polymer may be composed of a single polymer or of several polymers. The same advantageously applies for the second thermoplastic polymer.

In one preferred variant of the process, the daughter and mother tapes contain a first thermoplastic polymer that is melt-compatible with or preferably of the same nature as the second thermoplastic polymer used to produce the profile. For example, if the second thermoplastic polymer is chosen from vinyl chloride (VC) polymers (VC-derived homopolymers and/or copolymers), the first thermoplastic polymer is chosen from thermoplastic polymers that are melt- compatible with the VC polymers such as, in a non-limiting manner, polymethyl methacrylates, acrylic polymers and VC polymers themselves (of the same nature).

The expression "melt-compatible" is understood to mean, for the purposes of the present invention, that a single phase is observed in the melt state ; in other words, that a single glass transition temperature is observed in the melt state.

The expression "of the same nature" is understood to mean, for the purposes of the present invention, of the same chemical nature. Particularly preferably, the second thermoplastic polymer is chosen from VC homopolymers and/or copolymers and the first thermoplastic polymer is chosen from VC homopolymers and/or copolymers, homopolymers and/or copolymers of methyl methacrylate and those of acrylic monomers.

Very particularly preferably, the first thermoplastic polymer and the second thermoplastic polymer are of the same nature and are chosen from VC homopolymers and/or copolymers.

The first thermoplastic polymer may thus be constituted by a single VC polymer or several VC polymers. The same advantageously applies for the second thermoplastic polymer. If the first thermoplastic polymer and the second thermoplastic polymer are constituted by several VC polymers, these are of the same nature since they are polymers of VC but may differ in terms of their monomer composition (homopolymers or copolymers), their melt viscosity index (K- value) or their production process (polymerization in bulk, in solution, in aqueous suspension, in aqueous emulsion or in aqueous microsuspension).

Whilst being of the same nature, the VC polymer(s) constituting the first thermoplastic polymer may be identical to or different from, in terms of monomer composition, melt viscosity index or production process, that (or those) constituting the second thermoplastic polymer. Preferably, the VC polymer(s) constituting the first thermoplastic polymer is (are) different, in terms of monomer composition, melt viscosity index or production process, from that (or those) constituting the second thermoplastic polymer, whilst being of the same nature.

The expression "VC homopolymers" is understood to mean, within the present description, polymers containing 100 % by weight of VC-derived monomer units.

The expression "VC copolymers" is understood to mean, within the present description, copolymers containing at least 50 % by weight, and preferably at least 70 % by weight, in particular between 75 and 95 % by weight of

VC-derived monomer units, the balance being monomer units derived from one or more monomers that are copolymerizable with VC. As examples of comonomers that are copolymerizable with VC, mention may be made of unsaturated olefinic monomers, such as ethylene, propylene and styrene, but also esters such as vinyl acetate (VAC) and alkyl acrylates and methacrylates. The present invention is particularly well-suited to VC homopolymers and VC/VAC copolymers. For the first thermoplastic polymer, use is preferably made, within the context of the invention, of fluid PVCs, that is to say PVCs having a low melt viscosity index or K-value (conventionally known as K _w or K-wert), i.e. less than or equal to 68, preferably 60, and very particularly preferably less than or equal to 58. For practical reasons (commercial availability), PVCs having a K _w greater than or equal to 50 are preferably used. It should, however, be noted that more fluid grades could no doubt be suitable.

The particle size of the powder of the first thermoplastic polymer used is preferably fine. Thus, the average diameter of the particles is preferably less than or equal to 300 μm, or even 200 μm and most particularly preferably 150 μm.

Conventionally, the first and/or second thermoplastic polymer may contain customary additives such as stabilizers, pigments, lubricants, etc. These additives may be liquid or solid. The presence of a heat stabilizer is particularly recommended since the process according to the invention involves a pressurized heating step. When it is used, for example for the first thermoplastic polymer, the heat stabilizer is preferably present in an amount of at least 2, or at least 5 and even up to 10 parts per 100 parts of resin. It may be of any type (Pb, Ca-Zn, Sn, etc.), tin giving good results. Stabilizers that are liquid at ambient temperature, preferably that are liquid at the temperatures attained by the powder during its preparation, will be preferred. Another advantage is that the customary formulations, including, in particular, processing aids, reinforcing agents and lubricating agents, may be simplified, especially by omitting said aids or agents.

The fibres used in the process according to the invention may be any commercially available fibres. They may be organic fibres (from natural products such as hemp or flax for example, or from synthetic products such as polymer fibres) and/or mineral fibres (glass fibres for example). The polymer fibres advantageously do not undergo any modification such as melting or deformation during steps (a), (b) and (c) of the process. Indeed, these fibres should preferably be prevented from melting and therefore their melting temperature is particularly preferably above the melting temperature of the first thermoplastic polymer. The process gives good results with mineral fibres and particularly good results with glass fibres.

Within the context of the invention, the expression "long chopped fibres" is understood to mean fibres having an average length, after having been chopped, that is advantageously between 1 and 20 cm. Their average length is

advantageously greater than or equal to 1 cm, preferably greater than or equal to 1.5 cm and particularly preferably greater than or equal to 2 cm. Their average length is advantageously less than or equal to 20 cm, preferably less than or equal to 15 cm, particularly preferably less than or equal to 10 cm and very particularly preferably less than or equal to 8 cm.

The expression "fibres positioned in an isotropic manner" is understood to mean, for the purposes of the present invention, that the fibres are positioned randomly but in all spatial directions. In other words, the fibres are

advantageously positioned in any manner but in all spatial directions. The physical properties of the daughter tape are thus advantageously identical in all spatial directions.

It is known, according to patents EP 1 276 602 and US 5,792,529, that the fibres of the reinforced profile, which may be long (continuous) or very short (of the order of 0.6 to 2.5 cm) must be aligned or configured in an essentially parallel manner in order to provide the PVC with reinforcement and linear stability.

Surprisingly, it has actually been found that tapes based on continuous commingled PET fibres and glass fibres used in the prior art for reinforcing profiles could be replaced by tapes composed of a thermoplastic polymer and long chopped glass fibres positioned in an isotropic manner.

The content of the fibres is between 20 and 80 % by weight, preferably between 25 and 60 % by weight, in particular between 30 and 50 % by weight of the daughter tape.

In step (a) of the process, the fibres may have been coated with a coupling agent during the cycle of their manufacture, thus improving the impregnation homogeneity and the mechanical properties, thereby consolidating the daughter tape and consequently the mother tape, should there be one, and additionally allowing an easier recycling of the reinforced profile at end-of-life, and also of the production scrap. Among the coupling agents customarily used, mention may be made, non-exhaustively, of silanes, polyesters, acrylic or methacrylic polymers, waxes and epoxides. Among these, silanes are preferred. As examples, mention may especially be made of 3-aminopropyltrimethoxy-silane and 3-aminopropyltriethoxysilane and also derivatives thereof such as gamma- methacryloxypropyltrimethoxysilane, N-benzyl-N-aminoethyl-3- aminopropyltrimethoxysilane and the corresponding hydrochloride, N-phenyl-3- aminopropyltrimethoxysilane and N-2-(vinylbenzylamino)-ethyl-3 -aminopropyl- trimethoxysilane.

In step (a) of the process, before dispersion of the first thermoplastic polymer in powder form over the long chopped fibres, the long chopped fibres may firstly be positioned in an isotropic manner on a polymer film, preferably on a film of the first thermoplastic polymer. Preferably, said fibres are positioned in an isotropic manner on a polymer film, preferably on a film of the first thermoplastic polymer, before dispersion of the first thermoplastic polymer in powder form over the long chopped fibres positioned in an isotropic manner. A second polymer film, preferably a film of the first thermoplastic polymer, may then be deposited on the first thermoplastic polymer in powder form dispersed over the long chopped fibres positioned in an isotropic manner. Preferably, this second polymer film is deposited.

In step (a) of the process, after dispersion of the first thermoplastic polymer in powder form over the fibres, an AC electric field is applied. This operation has the effect of advantageously distributing the powder in the fibres.

Any AC electric field (also called alternating electrical field) can be applied as long as the powder is well distributed in the fibres. Good results have nevertheless been obtained by applying an AC electric field of at least

0.10 kV/mm and preferably of at most 20 kV/mm.

In step (a) of the process, after dispersion of the first thermoplastic polymer in powder form over the fibres and applying an AC electric field, heating under pressure is carried out.

Heating under pressure is advantageously carried out under a pressure of a few bar, preferably under a pressure less than or equal to 2 bar, particularly preferably under a pressure of around 1.5 bar. According to one preferred embodiment, the heating under pressure is carried out by passing between two conveyor belts, heated to the processing temperature of the powder of the first thermoplastic polymer, followed by passing between two rolls, preferably hot rolls, which provide the pressure, and then by passing the daughter tape obtained between two cooled conveyor belts. The conveyor belts are preferably continuous so that the material is always between these belts, even during the pressing between the two rolls.

The cycle of heating under pressure followed by a cooling may be repeated, especially when the daughter tape has not achieved the desired density. It is then advantageous to repeat the cycle of the preferred embodiment described above. Any other embodiment may also be envisaged such as, for example, heating the daughter tape by infrared radiation or by hot rolls while transporting it, for example by means of conveyor belts, to the preferably hot, press rolls and of then cooling it by passing it between two cooled conveyor belts, between two cooled rolls or by using a flow of air. The daughter tape may then optionally be wound.

The daughter tape thus obtained is advantageously characterized by a density at least equal to 95 % of the theoretical density calculated by taking into account the composition of the daughter tape and the density of its constituents.

If necessary, after step (a), it is then possible to longitudinally cut the daughter tape(s) obtained to make daughter tapes having a width that is compatible with the width of the profile to be reinforced.

The expression "at least one daughter tape" is understood to mean, for the purposes of the present invention, that one or more daughter tapes can be manufactured in step (a). In the event that step (b) is not carried out, a single daughter tape is then manufactured in step (a) and used in step (c). In the event that step (b) is carried out, at least two daughter tapes are manufactured in step (a) in order to be superposed and welded in step (b).

Preferably, the process for manufacturing a rigid profile according to the invention comprises the manufacture of a mother tape according to step (b) and the manufacture of the reinforced profile according to step (c) using the mother tape obtained in step (b).

Advantageously, the welding of at least two daughter tapes in step (b) is carried out thermally by selective, and not total, melting of the surfaces by a heated wedge, by hot rolls, by infrared radiation or by a laser, preferably by a heated wedge or by a laser. For infrared or laser heating, it may be desirable to add a pigment that absorbs infrared radiation, for example carbon black. In order to avoid putting at least one of these absorbent agents into the bulk of the tape, it is moreover advantageous to coat the tape with a thin film containing at least one of these absorbent agents.

In the process according to the invention, a reinforced profile is

manufactured in step (c) by means of a daughter tape obtained in step (a) or of a mother tape obtained in step (b) by extruding a molten second thermoplastic polymer on at least one face of the daughter tape or on at least one face of the mother tape, preferably on all the faces of the daughter tape or on all the faces of the mother tape. In one preferred variant of the process according to the invention, the manufacture of the reinforced profile according to step (c) is carried out in a die.

In one particularly preferred variant of the process according to the invention, the daughter tape obtained in step (a) or the mother tape obtained in step (b) is introduced into a die, which is preferably calibrated to the cross section of the profile, with a simultaneous introduction of a molten second thermoplastic polymer into said die so as to obtain a profile reinforced by the daughter tape or by the mother tape, which is then introduced into the wall of the profile in a centred (relative to the width of the wall) or uncentred manner, said reinforced profile possibly being solid or hollow.

The tape entering, preferably into the die, in step (c) may be brought to an average temperature below or above the melting temperature for the semi- crystalline thermoplastic polymers or the glass transition temperature for the amorphous thermoplastic polymers that form the matrix. Preferably, the temperature is below the melting temperature for the semi-crystalline polymers or the glass transition temperature for the amorphous polymers that form the polymer matrix of the tape. In particular, said temperature of the tape is at most 40 ⁰ C below, preferably 20 ⁰ C below and in particular 10 ⁰ C below said melting temperature or glass transition temperature. The expression "average temperature" is understood to mean the average of the temperatures calculated across the cross section of the tape at the inlet to the die by any known analytical or numerical means.

In order to facilitate their adhesion to the molten second thermoplastic polymer (for example, molten PVC), preferably at the die, it is recommended to heat the two surfaces of the tape at the inlet of the die by any appropriate technique, preference being given to infrared heating. To avoid any cooling of the surface of the tape, the heating is preferably carried out less than 1 m before the inlet, preferably of the die, very preferably less than 0.5 m before the inlet.

Thus, the daughter and mother tapes obtained advantageously have isotropic mechanical strengths, and therefore the resulting reinforced profiles advantageously have a better multiaxial impact strength unlike the products of the prior art. Furthermore, this advantageously makes it possible to reduce the thicknesses of the walls of the profiles.

The tapes may be delivered as reels. When this is the case, the production line of the reinforced profile may be supplied with reels of tapes. When this is the case, it is then advantageous to connect the tape from the new reel to the tape delivered by the last reel without an increase in thickness and without loss of the mechanical properties provided by the fibres.

Consequently, one preferred variant of the process therefore also makes provision, in step (a) or in step (b), for the end-to-end joining of two tapes, which is carried out over a length of at least 10 cm along a punched cut-out of triangular and parallel shape in two tapes having a height of at least 1 cm and a base of at least 5 mm, followed by removal of the parts cut out upstream of the tape leaving the reel to be replaced and downstream of the tape coming from the new reel, an application of adhesive to at least one of the edges of the tape and flat interlocking of the two ends of the two tapes. It is preferred, after having removed the parts cut out upstream and downstream of each tape, to weld together the interlocked ends using a laser.

The daughter or mother tapes may be produced by a process that is or is not in line with the manufacture of the profile ; in the event that the tape is manufactured in line with the manufacture of the profile, the joining system described above is unnecessary.

Particularly preferably, the process according to the invention is such that step (a) is carried out in line with step (b) and step (c).

Depending on the length of the profile and on its own stiffness (provided by the design and the thicknesses of the walls of the profile), the required thickness of the tape may be variable.

The thickness of the tape used for manufacturing the reinforced profile is advantageously at least 0.5 mm, preferably at least 1 mm, particularly preferably at least 1.5 mm. It is advantageously at most 5 mm, preferably at most 3 mm and particularly preferably at most 2 mm. Thus, if the tape obtained in step (a) is characterized by a thickness below that desired, step (b) takes place so as to manufacture a tape of greater thickness.

Another aspect of the present invention therefore relates to a reinforced profile as described above in relation to the process. In particular, the invention proposes a reinforced profile comprising a tape that serves as reinforcement, said tape containing a first thermoplastic polymer and long chopped fibres, and also a second thermoplastic polymer applied in the melt phase to at least one face of said tape. The features and preferences given previously for the process according to the invention apply to the reinforced profile according to the invention. Finally, another aspect of the present invention relates also to the use of the profile according to the invention or of the reinforced profile obtained by the process described above, for the manufacture of shutters, doors, gates, window frames, coverings for walls and ceilings (panelling, boards), cable conduits and skirting boards. Preferably, the reinforced profile according to the invention is used for the manufacture of shutters, doors, gates, window frames, coverings for walls and ceilings (panelling, boards) and skirting boards. Particularly preferably, it is used for the manufacture of shutters, doors, gates and window frames, and very particularly preferably for the manufacture of window frames.

When the reinforced profile is used for the manufacture of a window frame comprising at least one hollow chamber, then the latter may optionally be filled with a light plastic of low density, for example of polyurethane foam type, for better thermal insulation.

Other particularities and features of the invention will appear from the detailed description of an advantageous embodiment given below, by way of illustration, with reference to the appended drawing. This shows :

Fig. 1 : a diagram of a reinforced profile used for the manufacture of a window frame comprising at least one hollow chamber.

Figure 1 shows a reinforced profile 1 that can be used for the manufacture of a window frame comprising at least one hollow chamber 5 which may optionally be filled with a foam (polyurethane foam for example, not shown), which is reinforced by the insertion of at least one mother tape 3 introduced at the centre of a wall between the external part 2 and the internal part 2' of said reinforced profile, preferably obtained according to the manufacturing process of the invention. The reinforced walls of the profile 1 comprise the second thermoplastic polymer, which is preferably melt-compatible with or of the same nature as the first thermoplastic polymer of the mother tape 3 thus facilitating the recycling of said reinforced profile at end-of-life or of production scrap.