EP3997160A1

EP3997160A1 - Method for preparing an impregnated fibrous material by reactive pultrusion

Info

Publication number: EP3997160A1
Application number: EP20750321.0A
Authority: EP
Inventors: Yves Deyrail; Gilles Hochstetter; Thomas BOUCHERES; Adrian CAUSIER
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2019-07-09
Filing date: 2020-07-07
Publication date: 2022-05-18
Also published as: EP3763775A1; FR3098517B1; FR3098517A1; EP3763775B1; JP2022540444A; CN114096401B; KR20220034161A; ES2897466T3; WO2021005302A1; US20220275157A1; CN114096401A

Abstract

The present invention concerns a method for manufacturing at least one impregnated fibrous material comprising a fibrous material made of continuous fibres and at least one thermoplastic polymer having a glass transition temperature Tg of not less than 40°C, or a melting temperature Tm of not more than 400°C, characterized in that said method comprises a step of impregnating said at least one fibrous material in a pultrusion head by injecting a reactive composition in the melt state comprising at least one precursor of said thermoplastic polymer in the presence of said fibrous material, said at least one fibrous material on entry into said pultrusion head being divided in its thickness into n layers, especially of substantially equal thickness, where n is from 2 to 20, with each layer circulating in its own channel within said pultrusion head, said reactive composition being injected into each channel and/or between said layers when they are recombined at the exit from each channel, said channel being heated at a temperature such that the initial melt viscosity of the reactive composition is less than 50 Pa.s, with impregnation starting at the moment of injection and ending before or after said layers are recombined by superposition to form said at least one final impregnated fibrous material, in which said precursors of said thermoplastic polymer are at least partly polymerized.

Description

DESCRIPTION

TITLE: PROCESS FOR THE PREPARATION OF A FIBROUS MATERIAL IMPREGNATED BY REACTIVE PULTRUSION [Technical field]

The present invention relates to a process for preparing a fibrous material impregnated with a thermoplastic polymer by reactive pultrusion, the tapes obtained by the process and their use.

[Prior art]

In traditional thermoplastic pultrusion, the impregnation resin is a non-reactive or slightly reactive polymer of sufficiently low viscosity (<100 Pa.s) to be able to impregnate the strands of fibers (rovings) at a line speed of between 0.2 to lm / min while keeping a reasonable head length so as to limit the friction surface on the rovings as well as the machining cost. The impregnation of a roving can be characterized by a diffusion time of the resin in the heart of the roving. This diffusion time is a function of several factors such as the viscosity of the thermoplastic polymer, the speed of the line and the thickness of the roving.

In impregnation techniques, the use of bindings is known to reduce the diffusion time of the resin through the roving and to homogenize the distribution of the fibers by going from a roving of circular section to a rectangular section of ratio. very high width / thickness (large width, low thickness).

This is done by circulating the roving alternately above and below a series of contact surfaces while applying tension to the roving. The jams can be upstream of the sector and / or inside the sector. The upstream jams have the role of expanding the roving and the jams inside the die make it possible to generate a roving / solid contact zone.

Thus, international application WO2013086258 describes the impregnation of a fibrous material with a non-reactive thermoplastic polymer by passing a wick or roving through an impregnation zone in the pultrusion head in a channel in which the thermoplastic polymer is injected. at the entrance to the channel on one of the surfaces of said wick to obtain an asymmetric impregnated fibrous material, that is to say that the impregnated fibrous material has a portion rich in fiber and a portion rich in thermoplastic polymer in the direction of the thickness.

Each channel present in the pultrusion head is equipped with several contact surfaces allowing the friction of the wick so as to reduce the diffusion time of the thermoplastic polymer through the roving.

The maximum tensile force that the wicks can withstand ranges from 1000 to 15000 MPa for wicks having a mass per unit length of 0.05 to 2g / m. The viscosity in the state melt of the thermoplastic polymer used is from 25 to 50,000 Pa.s. It is of course understood by those skilled in the art that such high viscosities do not make it possible to impregnate in sufficiently rapid times and / or over sufficiently large thicknesses to be of any interest from an industrial point of view.

If we consider a roving which passes through the impregnation head in a channel, this roving at any time during its journey is included in the volume of the channel, composed of the volume of the roving and a free volume. Without this free volume, the fiber would occupy the entire volume of the canal, leading to very significant friction on the walls and the premature rupture of the rovings. It is therefore this free volume, necessary for the process, which generates a residence time of the resin in the head but said residence time must be limited to the maximum while still allowing the diffusion of the polymer.

thermoplastic in the roving and not have too much viscosification of the resin before impregnation which would prevent impregnation or block the pultrusion head.

Furthermore, when a mixture of prepolymers is used for the polymerization, the latter must be sufficiently fluid to be able to impregnate the fibers with this reactive mixture. It is therefore necessary to heat at high temperature to carry out the impregnation, in particular when the Tg of the prepolymers is high, but then the polymerization reaction then becomes too rapid and the viscosification prevents the correct impregnation of the fibers.

[Summary of the invention]

The invention therefore relates to a method of manufacturing at least one impregnated fibrous material comprising a fibrous material in continuous fibers and at least one thermoplastic polymer with a glass transition temperature Tg greater than or equal to 40 ° C, in particular greater than or equal to 80 ° C, preferably from 100 to 200 ° C, more preferably from 110 to 200 ° C, or a melting temperature Tf less than or equal to 400 ° C, in particular less than or equal to 350 ° C, in particular less or equal to 290 ° C,

characterized in that said method comprises a step of impregnating in a pultrusion head said at least one fibrous material by injection of a reactive composition in the molten state

comprising at least one precursor of said thermoplastic polymer in the presence of said fibrous material,

said at least one fibrous material being during its entry into said pultrusion head divided in its thickness into n layers, in particular of substantially equal thicknesses, n being comprised from 2 to 20, in particular from 2 to 10, more particularly from 2 to 5, in particular equal to 4,

each layer circulating in said pultrusion head in a channel which is specific to it,

the injection of said reactive composition being carried out in each channel and / or between said layers during their reunification at the outlet of each channel, said channel being heated to a temperature such that the reactive composition has an initial viscosity in the molten state of less than 50 Pa.s, more preferably less than 20 Pa.s, even more preferably less than 10 Pa.s, in particular less than 5 Pa.s, the impregnation starting at the time of injection and ending before or after the reunification of said layers by superposition to form said at least one final impregnated fibrous material in which said precursors of said thermoplastic polymer are at least partially polymerized.

The inventors have unexpectedly found that dividing the thickness of a fibrous material to be impregnated with a reactive composition, into several layers, in particular of substantially equal thickness, each layer circulating in a channel heated to a temperature such that the reactive composition which comprises precursors (also called reactive oligomers or also called reactive prepolymers) of low starting or initial viscosity in the molten state (<50 Pa.s) and which will impregnate said layers made it possible to reduce to a minimum the diffusion time of the reactive composition in said layers and therefore of impregnating said layers before or after their reunification while carrying out the polymerization at least partially.

In other words, the process of the invention makes it possible to ensure the double constraint which is to raise the initial viscosity sufficiently to have molar masses (Mn) of the polymer sufficiently high so as to have good mechanical strength and " controlling »this rise in viscosity / mass so as to ensure impregnation before the viscosity becomes too high.

This process also makes it possible to minimize the dead volume in each channel.

This process therefore makes it possible to achieve line speeds greater than 1 m / min and thus significantly reduce the manufacturing costs of pultruded profiles.

In addition, the reactivity of the oligomers makes it possible, after complete polymerization, to achieve mechanical properties that are much higher than what is obtained in traditional pultrusion, at equivalent impregnation quality.

The glass transition temperature Tg and the melting temperature Tf are measured in DSC according to ISO 11357-2: 2013 and ISO 11357-3: 2013.

The viscosity in the molten state is measured by oscillatory rheology at a temperature Tf <T <Tf + 50 ° C for a semi-crystalline polymer or Tg + 220 ° C for an amorphous polymer, at 10 rad / sec under sweeping of nitrogen with 5% deformation on a Physica MCR301 apparatus between two parallel planes 25 mm in diameter.

A semi-crystalline polymer, within the meaning of the invention, denotes a polymer which exhibits a

melting temperature (Tf) in DSC according to standard ISO 11357-3: 2013, and an enthalpy of crystallization during the cooling step at a speed of 20K / min in DSC measured according to standard ISO 11357-3 of 2013 higher or equal to 30 J / g, preferably greater than or equal to 35 J / g. An amorphous polymer, within the meaning of the invention, denotes a polymer exhibiting only a glass transition temperature (no melting point (Tm)) in DSC according to the ISO 11357-2: 2013 standard, or a very low crystalline polyamide having a glass transition temperature in DSC according to ISO 11357-2: 2013 and a melting point such as the enthalpy of crystallization during the cooling step at a speed of 20K / min in differential scanning calorimetry ("Differential Scanning Calorimetry »DSC) measured according to the ISO 11357-3: 2013 standard is less than 30 J / g, in particular less than 20 J / g, preferably less than 15 J / g.

The expression “of substantially equal thickness” means that each layer after separation of the fibrous material (or wick) has a thickness e ± 25%, in particular ± 12%.

Each layer circulates in its own channel, so there is only one layer per channel and therefore there cannot be two or more layers per channel.

Regarding the reactive composition:

The expression “reactive composition” means that the molecular weight of said reactive composition (or its viscosity in the molten state) will change during the use by reaction of prepolymers (or oligomers) reactive with themselves or with each other by condensation or with a chain extender by polyaddition and without elimination of volatile by-products to lead, after polymerization or by complete nucleophilic substitution, to the final polyamide polymer of the thermoplastic matrix.

In the case of the reactive compositions of the invention, said reactive prepolymers are prepared by conventional polycondensation reaction between the corresponding diamine and diacid components and optionally amino acids or lactams. The prepolymers bearing X and Y amine and carboxy functions on the same chain can be obtained for example by adding a combination of monomers (amino acid, diamine, diacid) having in total an equal amount of amine and carboxy units. Another way of obtaining these prepolymers carrying an X function and a Y is, for example, by combining a prepolymer carrying 2 identical functions X = amine, with a diacid prepolymer carrying Y = carboxy, with an overall molar ratio in acid functions equal to that of the starting amine functions X.

To obtain prepolymers functionalized with identical functions (amines or carboxy) on the same chain, it suffices to have an excess of diamine (or of amine functions overall) in order to have terminal amine functions or excess of diacid (or of carboxy functions globally) to have carboxy terminal functions.

According to a first possibility, said at least partially polymerized reactive thermoplastic prepolymer comprises at least one reactive prepolymer (in particular polyamide) carrying, on the same chain (that is to say on the same prepolymer), two terminal functions X 'and Y 'functions respectively coreactive with each other by condensation, with X' and Y 'being amine and carboxy or carboxy and amine respectively. Advantageously, said at least partially polymerized reactive thermoplastic prepolymer consists of at least one reactive prepolymer (in particular polyamide) carrying on the same chain (that is to say on the same prepolymer), of two terminal functions X 'and Y 'functions respectively coreactive with each other by condensation, with X' and Y 'being amine and carboxy or carboxy and amine respectively.

There is therefore no presence of a chain extender in this first embodiment.

According to a second possibility, said at least partially polymerized reactive thermoplastic prepolymer comprises at least two polyamide prepolymers reactive with each other and each carrying respectively two terminal functions X 'or Y', identical (identical for the same prepolymer and different between the two prepolymers), said X 'function of a prepolymer being able to react only with said Y' function of the other prepolymer, in particular by condensation, more particularly with X 'and Y' being amine and carboxy or carboxy and amine respectively.

Advantageously, said at least partially polymerized reactive thermoplastic prepolymer consists of at least two polyamide prepolymers which are reactive with each other and with each carrier.

respectively of two terminal functions X 'or Y', identical (identical for the same prepolymer and different between the two prepolymers), said function X 'of a prepolymer being able to react only with said function Y' of the other prepolymer, in particular by condensation, more particularly with X 'and Y' being amine and carboxy or carboxy and amine respectively.

The at least two prepolymers may or may not be mixed together beforehand.

This condensation (or polycondensation) reaction can cause the appearance of by-products.

There is therefore no presence of chain extender in this second embodiment.

The reaction of the two prepolymers can be total or partial.

According to a third possibility, said at least reactive thermoplastic prepolymer partially polymerized with the chain extender comprises:

al) at least one reactive thermoplastic prepolymer as already defined above with this prepolymer carrying n terminal reactive functions X, identical chosen from: -NH2 (amine), - C02H (carboxy) and -OH (hydroxyl), preferably - NH2 (amine) and -CO2H (carboxy), with n being 1 to 3, preferably 1 to 2, more preferably 1 or 2, more particularly 2

a2) at least one Y-A'-Y chain extender, with A 'being a hydrocarbon-based biradical, carrying 2 identical terminal reactive functions Y, reactive by polyaddition (without elimination of reaction by-product), with at least one function X of said prepolymer a1), preferably of molecular mass less than 500 and more preferably less than 400.

Advantageously, said at least reactive thermoplastic prepolymer partially polymerized with the chain extender consists of a1) and a2) defined above. Advantageously, Y is chosen from: oxazine, oxazoline, oxazolinone, oxazinone, imidazoline, epoxy, isocyanate, maleimide, cyclic anhydride, in particular oxazine, oxazoline, oxazolinone, oxazinone, imidazoline, maleimide, cyclic anhydride and preferably XI is C02H and Y1 is chosen from an epoxy and an oxazoline.

NH2 (amine) stands for primary and secondary amine.

As suitable examples of extenders a2) as a function of the X functions carried by said semi-crystalline polyamide prepolymer a1), the following may be mentioned:

- when X is NH2 or OH, preferably NH2:

either the chain extender Y-A'-Y corresponds to

Y chosen from the groups: maleimide, optionally blocked isocyanate, oxazinone and oxazolinone, cyclic anhydride, preferably oxazinone and oxazolinone, in particular maleimide, oxazinone and oxazolinone, cyclic anhydride, preferably oxazinone and oxazolinone

and

A 'is a spacer or a carbon radical carrying the functions or reactive groups Y, chosen from: a covalent bond between two functions (groups) Y in the case where Y = oxazinone and oxazolinone or

an aliphatic hydrocarbon chain or an aromatic hydrocarbon chain and / or

cycloaliphatic, the latter two comprising at least one ring of 5 or 6 carbon atoms optionally substituted, optionally with said aliphatic hydrocarbon chain optionally having a molecular weight of 14 to 200 g.mol-1

either the chain extender Y-A'-Y corresponds to Y being a caprolactam group and to A 'which may be a carbonyl radical such as carbonyl biscaprolactam or to A' which may be a terephthaloyl or an isophthaloyl,

either said chain extender Y-A'-Y carries a cyclic anhydride group Y and preferably this extender is chosen from a cycloaliphatic and / or aromatic dianhydride carboxylic and more preferably it is chosen from: ethylenetetracarboxylic dianhydride, pyromellitic dianhydride , 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1, 4,5,8-naphthalenetetracarboxylic dianhydride, perylenetetracarboxylic dianhydride, 3, 3', 4,4'-benzophenone tetracarboxylic, dianhydride 1, 2,3,4-cyclobutanetetracarboxylic, hexafluoroisopropylidene bisphthalic dianhydride, 9,9-bis (trifluoromethyl) xanthenetetracarboxylic dianhydride, 3, 3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, [2.2-octetracarboxylic dianhydride [2.2] -ene-2,3,5,6-tetracarboxylic, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyl tetracarboxylic ether or mixtures thereof

and - when X is COOH:

said Y-A'-Y chain extender corresponds to:

Y chosen from the groups: oxazoline, oxazine, imidazoline or aziridine, such as 1, l'-iso- or tere-phthaloyl-bis (2-methyl aziridine) or epoxy,

A 'being a spacer or a carbon radical as defined above.

More particularly, when in said extender Y-A'-Y, said function Y is chosen from oxazinone, oxazolinone, oxazine, oxazoline or imidazoline, in particular oxazoline, in this case, in the chain extender represented by Y-A ' -Y, A 'can represent an alkylene such as - (CH2) m- with m ranging from 1 to 14 and preferably from 2 to 10 or A' can represent a cycloalkylene and / or a substituted (alkyl) or unsubstituted arylene , such as benzene arylenes, such as o-, m-, -p phenylenes or naphthalene arylenes and preferably A ′ is an arylene and / or a cycloalkylene.

In the case of carbonyl- or terephthaloyl- or isophthaloyl-biscaprolactam as chain extender Y-A'-Y, the preferred conditions avoid the elimination of by-product, such as caprolactam during said polymerization and used in the process. molten state.

In the case where Y is an epoxy, the chain extender can be chosen from bisphenol A diglycidyl ether (DGEBA), and its hydrogenated derivative (cycloaliphatic) bisphenol F diglycidyl ether, tetrabromo bisphenol A diglycidyl ether, or hydroquinone diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4- butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether diglycidyl ether, polyethylene glycol <500 , polypropylene glycol diglycidyl ether of Mn <500, polytetramethylene glycol diglycidyl ether of Mn <500, resorcinol diglycidyl ether, neopentylglycol diglycidyl ether, bisphenol A polyethylene glycol diglycidyl ether of Mn <500, bisphenol A

polypropylene glycol diglycidyl ether of Mn <500, diglycidyl esters of dicarboxylic acid such as the glycidyl ester of terephthalic acid or epoxidized diolefins (dienes) or epoxidized double ethylenically unsaturated fatty acids, diglycidyl 1,2-Cyclohexanedicarboxylate and mixtures thereof.

In the possible case mentioned above where Y represents a blocked isocyanate function, this blocking can be obtained by blocking agents of the isocyanate function, such as epsilon-caprolactam, methyl ethyl ketoxime, dimethyl pyrazole, diethyl malonate.

Likewise, in the case where the extender is a dianhydride reacting with a prepolymer P (X) n where X = NH2, the preferred conditions avoid any formation of an imide ring during the polymerization and during the processing in the state. molten. For X = OH or NH2, the Y group is preferably chosen from: isocyanate (unblocked), oxazinone and oxazolinone, more preferably oxazinone and oxazolinone, with as spacer or hydrocarbon radical A ′ being as defined above.

As examples of chain extenders carrying reactive Y oxazoline or oxazine functions suitable for the implementation of the invention, reference may be made to those described under references "A", "B", "C" and "D". on page 7 of application EP 0 581 642, as well as their methods of

preparation and their reaction modes described therein. "A" in this document is bisoxazoline, "B" is bisoxazine, "C" is 1,3 phenylene bisoxazoline and "D" is 1,4-phenylene bisoxazoline.

By way of example, in the case where X = C02H and the chain extender Y-A'-Y is 1,4-phenylene bisoxazoline, the reaction product obtained has at least one repeating unit of the following structure: - 0-C (0) -PC (0) -0-Rl-NH-C (0) -A'-C (0) -NH-Rl- in which:

P is a polyamide containing H0-C (0) -P-C (0) -0H acid terminations obtained from the amide units (A), (B) or (C),

RI (CH2) 2, and

A 'is phenyl.

As examples of chain extenders with a reactive Y imidazoline function suitable for implementing the invention, reference may be made to those described (“A” to “F”) on page 7 to 8 and Table 1 of the invention. page 10 in application EP 0 739 924 as well as to their preparation processes and their reaction modes which are set out therein.

As examples of chain extenders with a reactive function Y = oxazinone or oxazolinone which are suitable for the implementation of the invention, reference may be made to those described under references "A" to "D" on page 7 to 8 of application EP 0 581 641, as well as to their preparation processes and their reaction modes which are described therein.

As examples of suitable oxazinone (6-atom ring) and oxazolinone (5-atom ring) Y groups, mention may be made of the Y groups derived from: benzoxazinone, oxazinone or

oxazolinone, with the spacer A 'possibly being a single covalent bond with the respective corresponding extenders being: bis- (benzoxazinone), bisoxazinone and bisoxazolinone.

A 'can also be a C1 to C14 alkylene, preferably C2 to CIO but preferably A' is an arylene and more particularly it can be a phenylene (substituted by Y in positions 1,2 or 1,3 or 1, 4) or a naphthalene radical (disubstituted by Y) or a phthaloyl (iso- or terephthaloyl) or A ′ may be a cycloalkylene.

For the Y functions such as oxazine (ring 6), oxazoline (ring 5) and imidazoline (ring 5), the radical A 'can be as described above with A' possibly being a single covalent bond and with the extenders respective correspondents being: bisoxazine, bisoxazoline and bisimidazoline. Oh, maybe also C1 to C14, preferably C2 to C10 alkylene. The radical A 'is preferably an arylene and, more particularly, it can be a phenylene (substituted by Y in positions 1,2 or 1,3 or 1,4) or a naphthalene radical (disubstituted by Y) or a phthaloyl ( iso- or terephthaloyl) or A 'can be cycloalkylene.

In the case where Y = aziridine (nitrogenous heterocycle with 3 atoms equivalent to ethylene oxide by replacing the ether -O- by -NH-), the radical A 'can be a phthaloyl (1,1'iso- or terephthaloyl) with as an example of an extender of this type 1, isophthaloyl-bis (2-methyl aziridine).

The presence of a catalyst for the reaction between said prepolymer P (X) n and said extender Y-A'-Y at a rate ranging from 0.001 to 2%, preferably from 0.01 to 0.5% relative to total weight of the two co-reactants mentioned can accelerate the (poly) addition reaction and thus shorten the production cycle.

Such a catalyst can be chosen from: 4,4 'dimethyl aminopyridine, p-toluenesulphonic acid, phosphoric acid, NaOH and optionally those described for a polycondensation or

transesterification as described in EP 0425 341, page 9, lines 1 to 7.

According to a more particular case of the choice of said extender, A ′ may represent an alkylene, such as - (CH 2) m- with m ranging from 1 to 14 and preferably from 2 to 10 or represents an alkyl substituted or unsubstituted arylene, such as benzene arylenes (such as o-, m-, -p phenylenes) or

Naphthalenics (with arylenes: naphthalenylenes). Preferably, A ′ represents an arylene which may or may not be substituted benzene or naphthenic.

As already specified, said chain extender (a2) preferably has a molecular mass of less than 500, more preferably less than 400.

The said extender rate used varies from 1 to 20%, in particular from 5 to 20%, in particular from 10 to 20% by weight.

In the case of the reactive compositions of the invention according to definition a), said reactive prepolymers are prepared by conventional polycondensation reaction between the corresponding diamine and diacid components and optionally amino acids or lactams. The prepolymers bearing X 'and Y' amine and carboxy functions on the same chain can be obtained for example by adding a combination of monomers (amino acid, diamine, diacid) having in total an equal amount of amine and carboxy units. Another way of obtaining these prepolymers bearing a function X 'and a Y' is, for example, by combining a prepolymer bearing 2 identical functions X '= amine, with a diacid prepolymer bearing Y': carboxy, with an overall molar ratio of acid functions equal to that of the starting amine functions X '.

To obtain prepolymers functionalized with identical functions (amines or carboxy) on the same chain, it suffices to have an excess of diamine (or of amine functions overall) in order to have terminal amine functions or excess of diacid (or of carboxy functions globally) to have carboxy terminal functions. In the case of a P (Xl) n prepolymer with n identical XI functions, functionality 1 can be obtained in the presence of a monofunctional blocking component (monoacid or monoamine depending on the nature of XI = amine or carboxy).

An n = 2 functionality can be obtained from difunctional components: diamines and diacids with excess of one to fix XI depending on this excess.

For n = 3 for example, for a prepolymer P (Xl) n, a component must be present

trifunctional, for example the presence of a triamine (one mole per prepolymer chain) with a diamine in the reaction with a diacid. The preferred functionality for P (Xl) n is n = 2.

Optionally, the thermoplastic prepolymer or mixture of prepolymers

thermoplastics further comprises carbonaceous fillers, in particular carbon black or carbon nanofibrils, preferably chosen from carbonaceous nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or their mixtures. These charges allow electricity and heat to be conducted, and therefore facilitate the melting of the prepolymer matrix when it is heated.

The number average molecular weight Mn of said final thermoplastic polymer, that is to say after complete polymerization, is preferably in a range of 10,000 to 40,000, preferably 12,000 to 30,000 determined in particular by calculation from the level of terminal functions determined by potentiometric titration in solution and the functionality of said prepolymers. The Mn masses can also be determined by size exclusion chromatography or by NMR.

These Mn values may correspond to inherent viscosities greater than or equal to 0.8 as determined in m-cresol according to standard ISO 307: 2007 but by changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20 ° C).

Said precursor prepolymers have a number-average molecular mass Mn ranging from 500 to 10,000, preferably from 1000 to 6000, in particular from 2500 to 6000.

In one embodiment, said reactive composition comprises or consists of:

- 50 to 100% by weight of at least one precursor of said thermoplastic polymer,

- 0 to 50% by weight of at least one additive and / or at least one other thermoplastic polymer,

The additives can be chosen from, without being limited to these, specific additives capable of absorbing at the wavelength of a laser, such as for example a UV or IR laser, this allowing the use of the placement technology. automatic fibers (AFP), in the case where the latter uses a laser heating mode, to weld the composite tapes together, this in particular in the case of composite tapes based on glass or carbon fibers. Other additives such as thermal stabilizers can be added to the precursor composition and therefore be present in the material final thermoplastic composite as used in the final application parts, in particular these stabilizers being antioxidants, against thermo-oxidation and / or photo-oxidation of the polymer of the thermoplastic matrix. Said antioxidants are of the sterically hindered phenolic and / or sterically hindered amine type (known under the common name HALS). As a suitable example of such additives, there may be mentioned: carbon black (NC) in the form of NC powder or preferably in the form of masterbatches based on NC and polyethylene (PE) or NC and polyamide (PA ), Ti02 (titanium oxide), ZnO (zinc oxide) and in the case of an IR laser, indium tin oxide, (Indium Tin Oxide, marketed by Evonik) and thermal stabilizers as mentioned above - high. As an example of N + PE masterbatch with about 40% of CN include the EUTHYLEN ^® marketed by BASF. As an example of NC + PA masterbatch with about 15% of NC include RENOL BLACK ^® marketed by Clariance.

The additives can also be fillers which, in addition to long reinforcing fibers, can in particular be any filler known to those skilled in the art in the field of composites. They may in particular be charges which conduct heat and / or conduct electricity, such as metal powder, powdery carbon black, carbon fibrils, carbon nanotubes (CNTs) or carbide. of silicon, boron carbonitride, boron nitride or silicon. Reference may be made on this subject to application WO 2010/130930 by the Applicant.

It is obvious that long reinforcing fibers (or long fibrous reinforcements) are excluded from the additives. The additives can also be flame retardants, such as a metal salt chosen from a metal salt of phosphinic acid, a metal salt of diphosphinic acid, a polymer containing at least one metal salt of phosphinic acid, a polymer containing at least one metal salt of diphosphinic acid.

The expression “other polymers” denotes any non-reactive thermoplastic polymer and in particular a polyamide polymer, in particular an aliphatic, cycloaliphatic or aromatic polyamide, and which may be semi-crystalline or amorphous.

By non-reactive thermoplastic polymer is meant a polymer whose molecular weight is no longer likely to change significantly, that is to say that its molecular weight in number (Mn) changes by less than 50% during its Implementation.

Regarding the injection

The injection of said reactive composition is carried out in each channel, at a position which may be at the inlet of each channel, at the outlet of each channel or between the inlet and the outlet of each channel (in the latter case, there may be one or more injection points) and / or between said layers when they leave each channel.

In a first variant, the injection is carried out between said layers when they leave each channel. Advantageously, in this embodiment, the injection of said reactive composition is carried out between two layers, two by two, at the outlet of said channels, said two layers then being impregnated to form an impregnated bilayer material, each impregnated bilayer material then being assembled in its thickness with the others to form said final impregnated fibrous material. In a second variant, the injection is performed at the inlet of each channel.

In a third variant, the injection is performed at the inlet of each channel and between said layers when they leave each channel.

In a fourth variant, the injection is carried out at the inlet of each channel and between the inlet and the outlet of each channel.

In a fifth variant, the injection is performed between the inlet and the outlet of each channel and between said layers when they leave each channel.

In a sixth variant, the injection is performed at the input of each channel and between the input and the output of each channel and between said layers when they leave each channel.

Regarding channels and layers

The fibrous material consists of a set of rovings which can be up to several thousand.

The fibrous material, before impregnation, is during its entry into said pultrusion head divided in its thickness into n layers. It is quite evident that at least one fibrous material enters the pultrusion head and therefore, when several fibrous materials enter the pultrusion head, each fibrous material is divided in its thickness into n layers.

The constituents of the reactive composition are mixed in a supply channel, at the inlet or at the outlet of said channel.

The channels are heated to a temperature such that the reactive composition has an initial viscosity in the molten state of less than 50 Pa.s, more preferably less than 20 Pa.s, even more preferably less than 10 Pa.s, in particular less than 5 Pa.s.

The initial viscosity means the viscosity at the time t of mixing in the supply channel of said reactive composition, that is to say that when the reactive composition is introduced into the supply channel, the initial viscosity of said reactive composition is less than 50 Pa.s, more preferably less than 20 Pa.s, even more preferably less than 10 Pa.s, in particular less than 5 Pa.s, or when said reactive composition is introduced between said layers at the outlet of each channel, each layer having circulated in a channel which is heated, said layer is then itself at the temperature of said channel and the initial viscosity of said reactive composition is also less than 50 Pa.s, more preferably less than 20 Pa.s , even more preferably less than 10 Pa.s, in particular less than 5 Pa.s.

The low viscosity during the injection of said reactive composition allows rapid impregnation of said layer with said reactive composition. The impregnation begins at the time of injection and the polymerization of said reactive composition begins as soon as the constituents are mixed, ie a little time before the start of the impregnation.

Impregnation and at least partial polymerization are therefore concomitant in the process of the invention.

The impregnation, depending on the position of the injection ends either before the reunification of said layers if the injection is performed at the inlet and / or between the inlet and the outlet of each channel or after the reunification if the The injection is done between the input and the output of the channels and / or the output of each channel.

Reunification is obviously carried out by superposing said impregnated layers to obtain said impregnated fibrous material.

Depending on the position of the injection, the impregnation and the at least partial polymerization being concomitant in the process of the invention, said precursors impregnating said fibrous material are therefore at least partially polymerized after reunification of said layers.

The expression “at least partially polymerized” means that the number-average molecular mass has increased by a factor of at least 2, without however exceeding 10,000, preferably 8,000.

After reunification, said fibrous material impregnated with said at least partially polymerized precursors is still located in the pultrusion head, in a single channel having its own heating system and possible jams, which allows, if necessary, to finalize the 'impregnation and / or further polymerization of the reaction mixture.

In one embodiment, the method as defined above is characterized in that the maximum thickness e of each layer is such that the impregnation time of each layer is less than or equal to the time required for an increase in the Mn of the reactive composition in said layer, by a factor of 5, preferably by a factor of 3, in particular by a factor of 2.

In other words, the method as defined above is characterized in that the maximum thickness e of each n layer is subjected to the constraint of being less than or equal to a maximum limit defined as being proportional to the square root of l 'integral over the residence time t _Sf of said layer in the die of the function defined as equal to the ratio of the product of the permeability K by the fluid pressure exerted on said layer P by the product of the volume fraction ci _f of the composition in the fibrous medium by the viscosity of the reactive composition m, the aforementioned constant of proportionality C being less than or equal to 14, in particular less than or equal to 7, notably less than or equal to 3, namely:

[Math 1] Furthermore, the channel is defined as representing the volume in which a layer of fibrous material travels passing through the impregnation head.

If we consider a fibrous material chosen randomly in one of the layers which pass through the impregnation head in a channel, this roving at any time of its journey is included in the volume of the channel, composed of the volume of said roving composing the layer and a free volume. Without this free volume, the material would occupy the entire volume of the canal, leading to very high friction on the walls and the premature rupture of the rovings.

It is therefore this free volume, necessary for the process, which generates a residence time of the reactive composition, in the head, different from the residence time of the rovings (directly linked to the line speed). In one embodiment, the average residence time of the reactive composition in the head is at most equal to 3, preferably 2 and even more preferably 1.5 times the residence time of said fibrous material. This makes it possible to avoid a blockage of the head because of a locally too high viscosity which blocks the movement of the layers or prevents their good impregnation.

The channels can be of various shapes but in one embodiment, they may or may not be cylindrical, in particular cylindrical.

A cylinder is a ruled surface whose generatrices are parallel, that is to say a surface in space made up of parallel lines.

The ruled surface can therefore be square, rectangular, circular, elliptical (or oblong), conical, U-shaped, T-shaped ...

The thickness of the channel is a characteristic dimension of the base of the cylinder and therefore, if the base is square, then e = side of the square. If the base is a rectangle, then a characteristic dimension is the short side which corresponds to the thickness. If the base is circular, e = diameter.

If elliptical base, e = minor axis of the ellipse ...

In one embodiment, the channels are cylindrical in shape, and each channel having a thickness proportional to the thickness of each n layer, the thickness of each channel is between 2 and 3 times the thickness of each n layer. , in particular between 1.5 and 2 times the thickness of each layer.

Advantageously, the channels are cylindrical in shape with a rectangular surface.

Friction points or contact areas (or contact points) can be placed

alternately above and below said fibrous materials in each channel thus allowing the development of said layers of fibrous materials and / or allowing a reduction in the impregnation time because these points of contact allow an increase in pressure locally.

These contact points make it possible to generate a pad effect in the embarrassment / roving junction zone, which makes it possible to reduce the diffusion time. However, the number and the surface of the contact zones must be limited and have a sufficiently large radius of curvature so as not to lead to the breaking of said fibrous materials (rovings) by excess tension on the fibers.

In one embodiment, each channel is equipped with at least one contact zone having a radius of curvature greater than d / eps rupture (d / e), d being the diameter of the fibers of the fibrous material and eps being the deformation at the breaking of the fibers, placed alternately above or below the rovings during their journey in the impregnation head to cause and / or maintain a development of the fibrous material, possibly previously initiated upstream of the head, without damaging said fibrous material.

The deformation at break of the fibers is determined on a cylinder of carbon fiber / epoxy resin composite, by measuring the maximum elongation at break during a tensile test on this composite.

It is subsequently considered that the tensile strength of the resin in the direction of the fibers is negligible compared to the tensile strength of the fibers and therefore the elongation at break of the composite is that of the fibers.

ISO 527-4: 1997 or EN 2561 Type B (1996) can be used.

The radii of curvature of the contact areas on said fibrous material should not be too small so as not to damage the fibrous material.

Therefore, the radius of curvature should not be less than or equal to d / eps rupture (d / e) otherwise the fibrous material is damaged.

Advantageously, each channel has up to 5 contact zones.

In one embodiment, each channel is devoid of contact zones placed alternately above or below the rovings as they travel through the impregnation head, in particular when the channels are conical in shape.

Regarding the thermoplastic polymer

Said thermoplastic polymer is selected from: poly (aryl etherketones) (PAEK), in particular poly (etheretherketone) (PEEK) and poly (etherketonketone) (PEKK); polyaryl sulfones, in particular polyphenylene sulfones (PPSU); polyarylsulphides, in particular polyphenylene sulphides (PPS); polyamides (PA), in particular semi-aromatic polyamides (polyphthalamides) optionally modified by urea units; PEBAs, polyacrylates in particular polymethyl methacrylate (PMMA); polyolefins, in particular polypropylene, polylactic acid (PLA), polyvinyl alcohol (PVA), and fluoropolymers in particular polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) or

polychlorotrifluoroethylene (PCTFE); and mixtures thereof, in particular a mixture of PEKK and PEI, of preferably 90-10% by weight to 60-40% by weight, in particular 90-10% by weight to 70-30% by weight.

It is obvious that the thermoplastic polymer must be available in the form of a reactive prepolymer in order to be able to impregnate said fibrous material.

The nomenclature used to define polyamides is described in standard ISO 1874-1: 2011 "Plastics - Polyamide materials (PA) for molding and extrusion - Part 1: Designation", in particular on page 3 (tables 1 and 2) and is indeed known to those skilled in the art.

The polyamide can be a homopolyamide or a copolyamide or a mixture thereof.

In one embodiment, said at least thermoplastic polymer is selected from polyamides, in particular aliphatic polyamides, cycloaliphatic polyamides and semi-aromatic polyamides (polyphthalamides), PVDF, PEEK, PEKK, PEI and a PEKK mixture and of PEI.

In another embodiment, said at least thermoplastic polymer is selected from polyamides, in particular aliphatic polyamides, cycloaliphatic polyamides and semi-aromatic polyamides (polyphthalamides).

Advantageously, said thermoplastic polymer is a polymer whose glass transition temperature is such that Tg> 80 ° C or a semi-crystalline polymer whose melting temperature Tf>

150 ° C.

Advantageously, said thermoplastic polymer is:

an aliphatic polyamide chosen from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), or a mixture thereof or a copolyamide thereof ,

a semi-aromatic polyamide, optionally modified with urea units, in particular a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (diamine in Ca). (Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids ;

XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T , one PA 66 / 6T, one PA 6I / 6T, one PA MPMDT / 6T, one PA MXDT / 6T, one PA PA11 / 10T, one PA 5T / 10T, one PA

11 / 5T / 10T, one PA 11 / 6T / 10T, one PA MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, PA BACT / 10T / 6T, one PA 11 / BACT / 10T, one PA 11 / BACT / 6T, one PA 11 / MPMDT / 10T and one PA

11 / MXDT / 10T, and block copolymers, in particular polyamide / polyether (PEBA).

T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylene diamine and BAC corresponds to bis (aminomethyl) cyclohexane.

Optionally, the thermoplastic polymer or mixture of thermoplastic polymers further comprises carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably chosen from carbonaceous nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or their mixtures. These charges make it possible to conduct electricity and heat, and consequently make it possible to accelerate the melting of the polymer matrix when it is heated, in particular by IR.

It is obvious that these carbonaceous fillers are initially present in the reactive composition. Regarding the fibrous material

Regarding the fibers constituting said fibrous material, they are in particular continuous fibers selected from carbon, glass, silicon carbide, basalt-based, silica-based fibers, natural fibers in particular flax or hemp, lignin, bamboo, sisal, silk, or cellulosics, in particular viscose, or amorphous thermoplastic fibers with a glass transition temperature Tg greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or greater than Tf of said polymer or of said mixture of polymers when the latter is semi-crystalline, or the semi-crystalline thermoplastic fibers with a melting point Tf greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or greater than the Tm of said polymer or of said mixture of polymers when the latter is semi-crystalline, or a mixture of two or more of said fibers, preferably a mixture of fi bres of carbon, glass or silicon carbide, in particular carbon fibers.

Advantageously, the number of fibers in said fibrous material for carbon fibers is greater than or equal to 3K, in particular greater than or equal to 6K, in particular greater than or equal to 12K. Advantageously, the number of fibers in said fibrous material for carbon fibers is greater than or equal to 12K, in particular chosen from 12K, 24K, 48K, 50K and 400K, in particular 12K, 24K, 48 K and 50K.

Advantageously, the basis weight for the glass fiber is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, greater than or equal to 4800 Tex.

Tex means that 1000m of base yarn weighs 1g. These fibers constituting said fibrous material can be used alone or in mixtures. Thus, organic fibers can be mixed with mineral fibers to be impregnated with thermoplastic polymer and to form the impregnated fibrous material.

The rovings of organic fibers can have several grammages. They can also have several geometries.

In one embodiment, the fibrous material consists of continuous fibers of carbon, glass, basalt or based on basalt, or of silicon carbide or a mixture thereof, in particular carbon fibers.

The fibers of the fibrous material may or may not be sized.

The term “sized” designates the surface treatments applied to fibrous materials during their manufacture. It can also designate a fleeting pretreatment as a preamble to the prepreg step, whether it is done directly in line with the impregnation or not.

The term “unsized” means that the fiber is either originally unsized and that it has therefore not undergone any surface treatment, or else that the fiber has been de-sized before its use.

They are generally organic in nature (thermosetting or thermoplastic resin type) and very often formulated for the pre-impregnation of reinforcing fibers of polymers with a low melting point Tf or thermosetting polymers with a low Tg point.

These sizes are also useful for protecting dry fibers from damage upon contact with a guide system.

In the case of an unsized material, said fibrous material can comprise up to 0.1% by weight of a material of organic nature (thermosetting or thermoplastic resin type) called sizing.

In the case of a fleeting pretreatment carried out by the impregnator, for example as a preamble to the pre-impregnation of the reinforcing fibers step, the sizing can be an organic liquid such as water, a low or high alcohol. molecular weight (ethanol, methanol, isopropanol for example), a ketone (acetone, etc.) which will play the role of fleeting sizing; that is to say that it will be present for a short time in contact with the fiber to allow its handling in the "dry" state (ie before the prepreg) and that it will then be extracted from the composite material so as not to disturb the final characteristics of the composite.

In the case of a sized material, said fibrous material can comprise from 0.1% by weight to 2.5% by weight of a material of an organic nature (thermosetting or thermoplastic resin type) called size. Advantageously, the fibers of the fibrous material are sized.

With regard to the impregnated fibrous material

The amount of fibers in said impregnated fibrous material is between 45% to 80% by volume, preferably from 50 to 65% by volume, in particular from 54 to 60%. Advantageously, the level of porosity in said impregnated fibrous material is less than 10%, in particular less than 5%, in particular less than 2%.

It should be noted that a zero porosity level is difficult to access and that consequently, advantageously the porosity level is greater than 0% but less than the rates mentioned above.

The rate of porosity corresponds to the rate of closed porosity and can be determined either by electron microscopy or as being the relative difference between the theoretical density and the experimental density of said impregnated fibrous material as described in the examples part of the present invention.

Formatting step

Optionally, a step of shaping the wick or said parallel wicks of said impregnated fibrous material is carried out.

In one embodiment, said method defined above further comprises a step of shaping said wick or said parallel wicks of said impregnated fibrous material, by means of at least one calender or a heating shaper or cooling, in the form of a single unidirectional strip or a plurality of parallel strips, or in the form of a U or T-shaped profile or in the form of a rod or of a plurality of rods parallel unidirectional strips, said shaping device being in contact or not with said impregnation head.

Advantageously, the calendering or shaping step is carried out by means of a plurality of heating or cooling calenders, or heating or cold shapers mounted in parallel and / or in series with respect to the direction of travel of the strands of fibers.

A calendering system as described in WO 2015/121583 can be used.

Advantageously, it is carried out by calendering by means of at least one heating calender in the form of a single unidirectional strip or sheet or of a plurality of unidirectional parallel ribbons or plies with, in the latter case, said heating calender comprising a plurality of grooves calendering, preferably up to 200 calendering grooves, in accordance with the number of said tapes and with a pressure and / or a spacing between the rolls of said calender regulated by a servo system.

Advantageously, the calendering step is carried out by means of a plurality of heating calenders, mounted in parallel and / or in series with respect to the direction of travel of the strands of fibers. Advantageously, said (or said) heating calender (s) comprises (comprise) an integrated heating system by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous fillers in said thermoplastic polymer or mixture of polymers thermoplastics.

According to another embodiment, a belt press is present between the pultrusion head and the calender.

According to yet another embodiment, a series of post-polymerization ovens is present between the pultrusion head and the last shaper or the last calender.

Advantageously, the step of shaping said wick or said parallel wicks of said impregnated fibrous material, by calendering by means of at least one heating calender in the form of a single unidirectional strip or sheet or of a plurality of parallel strips or sheets unidirectional with, in the latter case, said heating calender comprising a plurality of calendering grooves, preferably up to 300 calendering grooves, in accordance with the number of said bands and with a pressure and / or a spacing between the rollers of said grille regulated by a servo-controlled system.

Advantageously, the calendering step is carried out by means of a plurality of heating calenders, mounted in parallel and / or in series with respect to the direction of travel of the strands of fibers.

Advantageously, said (or said) heating calender (s) comprises (comprise) an integrated heating system by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous fillers in said thermoplastic polymer or mixture of polymers thermoplastics.

In one embodiment, said (or said) heating calender (s) is (are) coupled to a complementary heating device, located before and / or after said (each) calender, in particular a device heating by microwave or induction coupled to the presence of carbonaceous charges in said polymer or in said mixture of polymers, or an infrared heater IR, or Laser or by direct contact with another heat source.

Regarding the ribbon

According to another aspect, the present invention relates to a unidirectional tape of impregnated fibrous material, in particular tape wound on a spool, characterized in that it is obtained by a process comprising a shaping step as defined above.

In one embodiment, said tape is characterized in that the thermoplastic polymer is an aliphatic polyamide chosen PA 6, PA 11, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012, PA 11 / 1010 or PA 12/1010 or a semi-aromatic polyamide such as a PA MXD6 and a PA MXD10 or chosen from PA 6 / 6T, PA 6I / 6T, PA 66 / 6T, PA 11 / 10T, PA 5T / 10T, PA 11 / 5T / 10T, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 6T, PA BACT / 10T and PA BACT / 10T / 6T, PA BACT / 10T / 11, PA BACT / 6T / 11, one PVDF, one PEEK, PEKK and one PEI or a mixture of these.

According to another aspect, the present invention relates to the use of the method as defined above, for the manufacture of calibrated ribbons suitable for the manufacture of three-dimensional composite parts, by automatic depositing of said ribbons by means of a robot.

In one embodiment, said ribbon of impregnated fibrous material, as defined above, is used in the manufacture of three-dimensional composite parts.

In one embodiment, said manufacture of said composite parts relates to the fields of transport, in particular automotive, oil and gas, in particular offshore, gas storage, aeronautics, nautical, rail; renewable energies, in particular wind turbines, tidal turbines, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical and electronics.

According to yet another aspect, the present invention relates to a three-dimensional composite part, characterized in that it results from the use of at least one unidirectional strip of impregnated fibrous material as defined above.

Other objects, advantages and characteristics will emerge from the description which follows, given by way of purely illustrative example and made with reference to the appended drawings in which:

[Fig. 1] describes the pultrusion head of Example 1 comprising a die, mounted at a square head, comprising a system for separating the fibers in several layers, by means of a jamming system immersed in a tank of molten resin : system suitable for the use of a non-reactive resin

The fibrous material is separated into four but in a single impregnation chamber. The separated fibrous material therefore does not circulate in a channel of its own.

[Fig. 2] shows a sectional view of the morphology of the fibrous material impregnated from example 1 (pultruded profile) with the non-reactive 11 / 10T / 10T resin, using the pultrusion head described in FIG. 1.

[Fig. 3] presents the pultrusion head comprising a straight die, without dead volume and without a system for separating fibers into different layers (according to S. Lecorre, LTN, Nantes, International Journal of Microstructure and Materials Properties · January 2012) of the example 3.

[Fig. 4] shows the morphology of the impregnated fibrous material (pultruded profile) with the pultrusion head described in FIG. 3, with a reactive composition of the 11 / 10T / 10T type.

[Fig. 5] presents the pultrusion head without dead volume and with a system for separating the fibrous material into different layers thus circulating in a channel which is specific to it of Example 4 according to the invention. [Fig. 6] shows the morphology of a section produced with the pultrusion head described in FIG. 5 (example 4), with a reactive composition of the 11 / 6T / 10T type.

[Fig. 7] shows the morphology of a profile produced with the pultrusion head described in FIG. 5 (example 5), with a reactive composition of the BACT / 10T type.

EXAMPLES

The following examples illustrate without limitation the scope of the invention.

Example 1: comparative

Preparation of a fibrous material impregnated with 11 / 6T / 10T by non-reactive pultrusion with separation of the fibers in several layers but in a single impregnation chamber

The polymer is an 11 / 10T / 10T with a mass of 10,000 g / mol. Its Tg is 115 ° C, its viscosity at 300 ° C is 70 Pa.s.

The process for manufacturing the composite plate is a pultrusion process with melt impregnation with a pultrusion head comprising a die, mounted at a square head.

The pultrusion head has a resin reservoir in which the fibers are separated into 4 layers by means of a tie-off system, as described in figure 1.

This pultrusion head has significant dead volumes.

The entire fiber reinforcement has a thickness of 1mm. After separation, each of the fiber layers has a thickness of about 250 μm.

The polymer is introduced in the form of granules, compounded beforehand with a thermally stabilizing agent, into an extruder which feeds the square head.

The temperature at which the fibers were impregnated was 300 ° C.

The line speed was 0.5 m / min.

The fiber used is Hypertex fiberglass of 3B SE4535

The fiber content was 60% by volume.

The profile obtained is a plate with a width of 200mm and a thickness of 1mm.

Result

The morphology of the profile obtained is shown in Figure 2: the impregnation of the fibers is excellent, however the speed of the line is low and cannot be accelerated if one wishes to maintain this quality of impregnation, which makes this pultrusion process not very productive with this type of resin.

In addition, the relatively low mass of the polymer used to limit its viscosity to 300 ° C., given its high Tg, prevents very high breaking properties from being achieved. Thus, the flexural stress at break remains less than 100OMPa, which is low, taking into account the fiber content (see Table 1). This is the consequence of a too low molar mass of the resin, which was deliberately limited to 10 OOOg / mol in order to have a sufficiently fluid polymer to be compatible with the non-reactive process at 300 ° C. In addition, it is observed in FIG. 3, that this low molar mass leads to microcracking of the pultruded profile under the effect of the residual stresses which appear during crystallization of the resin and cooling of the pultruded profile.

Example 2: Comparison

Preparation of a fibrous material impregnated with 11 / 6T / 10T by reactive pultrusion with separation of the fibers in several layers but in a single impregnation chamber

The same pultrusion head as in Example 1 is used but with a reactive composition composed of two reactive prepolymers of the 11 / 6T / 10T type, with a molar mass Mn of 2500 g / mol, exhibiting a viscosity in the molten state at 300 ° C included 1 Pa.s, one being finished diCOOH, the other diNH2. After polymerization, the resin has a Tg of 115 ° C.

The melting of the prepolymers is done separately by means of 2 extruders.

The prepolymers are introduced in the form of granules, into an extruder which feeds the square head.

The temperature at which the fibers were impregnated was 300 ° C.

The line speed was 0.8 m / min.

The fiber used is Hypertex fiberglass of 3B SE4535

The fiber content was 58% by volume.

The profile obtained is a plate with a width of 200mm and a thickness of 1mm.

The pultrusion head start-up protocol consists of using a single prepolymer to impregnate the fibers, until a stabilized speed is reached on the line. The second prepolymer is then introduced, which is mixed at 300 ° C. with the first prepolymer, by means of a static mixer of the Sulzer type, just before their introduction into the pultrusion head.

In this pultrusion head, the fibers are separated into 4 layers as in Example 1. All of the fibrous reinforcement has a thickness of 1 mm. After separation, each of the layers of fibers has a thickness of about 250 μm.

Result

The fiber impregnation is excellent but the production of the profile stops shortly after start-up because the fibers get stuck in the head. This is due to the presence of excessively large dead volumes in the pultrusion head, in which the reactive composition resides too long and therefore polymerizes, leading to a very significant viscosification of the resin and to the blocking of the fibers in about ten minutes, c 'That is to say for a time close to the polymerization time of the reactive composition and the time necessary to replace in the dead zones, the initial prepolymer by the reactive composition. This process is therefore not robust and therefore not viable.

Example 3: Comparison Preparation of a fibrous material impregnated with 11 / 6T / 10T by reactive pultrusion without separation of layers

The pultrusion head used is presented in figure 3, is similar to the design of the pultrusion head described in the work of Pr Steven Lecorre at LTN, in Nantes, International Journal of Microstructure and Materials Properties · January 2012). This pultrusion head is distinguished by the fact that the fibers occupy a volume close to the volume of the head, ie there is no significant dead volume. On the other hand, there is no separation of the fibers in several layers, while the thickness of the final profile is 1 mm. The fiber content is 60% by volume. The thickness of the fibrous reinforcement is 1mm before impregnation and the thickness of the air gap of the pultrusion head is 2.5mm. The pultrusion speed is 0.8 m / min.

The reactive composition used is composed of two reactive prepolymers of the 11 / 6T / 10T type, with a mass of 2500 g / mol and having a viscosity in the molten state at 300 ° C of 1 Pa.s, one being terminated diCOOH, the other diNH2. After polymerization, the resin has a Tg of 115 ° C.

The melting of the prepolymers is done separately by means of 2 extruders.

The temperature at which the fibers were impregnated was 300 ° C.

The line speed was 0.8 m / min.

The fiber used is Hypertex fiberglass of 3B SE4535

The fiber content was 59% by volume.

The profile obtained is a plate with a width of 200mm and a thickness of 1mm.

Result:

The absence of excessively large dead volumes in the pultrusion head allows the pultrusion process to continue for at least 2 hours without blocking, while the complete reaction time of the reactive composition at 300 ° C. is less than 5 minutes. On the other hand, the absence of separation into layers of the fibrous reinforcement does not allow good impregnation of the fibers, despite the low viscosity of the prepolymers used (cf. FIG. 4).

This process is therefore not compatible with reactive chemistry based on a high Tg polymer.

Example 4: Invention

Preparation of a fibrous material impregnated with 11 / 6T / 10T by reactive pultrusion with separation of layers The pultrusion head used is shown in Figure 5. This pultrusion head is distinguished by the fact that the fibers occupy a volume close to the volume of the head, that is to say that there is no dead volume. important. In addition, there is separation of the fibers in several layers, while the thickness of the final profile is 1 mm. The fiber content is 60% by volume. Thus, the total thickness of the fibrous reinforcement is 1 mm before impregnation and in the absence of tension, the thickness of the air gap of each channel used for each of the layers is 350 μm, while each of the layers of fibers, under tension has a thickness close to 250 μm.

The pultrusion speed is 1.5 m / min.

The melting of the prepolymers is done separately by means of 2 extruders.

The temperature at which the fibers were impregnated was 300 ° C.

The line speed was 1.5 m / min.

The fiber used is Hypertex fiberglass of 3B SE4535

The fiber content was 57% by volume.

The profile obtained is a plate with a width of 200mm and a thickness of 1mm.

At the outlet of the pultrusion head, 3 IR ovens of 2 m are placed in line which allow post-polymerization of the resin in the molten state, at a temperature of 300 ° C. Taking into account the line speed of 1.5m / min, the polymerization time was 4mn. The final shaping of the plate is carried out by means of a cold shaper, regulated at 200 ° C., placed at the outlet of the last polymerization oven.

Results:

The absence of excessively large dead volumes in the pultrusion head allows the pultrusion process to continue for at least two hours without blocking, while the complete reaction time of the reactive composition at 300 ° C. is less than 5 minutes. The separation into layers of the fibrous reinforcement allows good impregnation of the fibers (see figure 6). In addition, the low viscosity of the prepolymers used also allows a pultrusion speed of 1.5 m / min, which is a factor in the productivity of this process. Taking a sample of plate taken directly at the outlet of the pultrusion die made it possible to measure the molar mass of the resin at this stage of the process and the Mn found was 5200 g / mol (measurement made by NMR), this which confirms the fact that the polymerization in the pultrusion head is very partial, which accordingly limits the risks of overpressure and degradation of the fibers, or even of complete blockage of the pultrusion head.

The fact of using a reactive process makes it possible, after the post-polymerization step and passage through the last cold shaper, to obtain a composite having excellent mechanical properties: in this case, the bending is measured, according to standard ISO 14125: 1998, a tensile strength> 1000 MPa (see table 1). This reflects the fact that a large molar mass has been reached in the pultruded profile and this is also accompanied by the disappearance of the microcracks (fig 6) which were present in the profile made with the non-reactive process (fig 3).

In addition, the fact of using a reactive chemistry made it possible to impregnate the fibers at high speed (ie above 1 m / min) at relatively low temperature (ie 300 ° C.). By way of comparison and to clearly show the interest of the invention, a polymer of mass equivalent to the mass obtained after post polymerization, should have been heated to more than 360 ° C to be sufficiently fluid to allow impregnation of the fibers in the using a non-reactive process. It would also have been necessary to have a very effective thermal stabilization to avoid its degradation, which remains complicated with PPAs. Finally, the cost of pultrusion equipment increases a lot above 330 ° C.

This reactive process is therefore compatible with reactive chemistry based on a high Tg polymer.

Example 5: Invention

Preparation of a fibrous material impregnated with BACT / 10T by reactive pultrusion with separation of layers

The pultrusion head used is shown in Figure 5. This pultrusion head is distinguished by the fact that the fibers occupy a volume close to the volume of the head, that is to say that there is no dead volume. important. In addition, there is separation of the fibers in several layers, while the thickness of the final profile is 1 min. The fiber content is 60% by volume. Thus, the total thickness of the fibrous reinforcement is 1.2mm before impregnation and in the absence of tension, the thickness of the air gap of each channel used for each of the layers is 350 μm, while each of the layers of fibers, under tension has a thickness close to 250 μm.

The pultrusion speed is 1.5 m / min.

The reactive composition used is composed of two reactive prepolymers of the BACT / 10T type, with a mass of 2800 g / mol and having a viscosity in the molten state at 320 ° C. of 4 Pa.s, one being terminated diCOOH, the other diNH2. After polymerization, the resin has a Tg of 140 ° C.

The melting of the prepolymers is done separately by means of 2 extruders. The prepolymers are introduced in the form of granules, into an extruder which feeds the square head.

The temperature at which the fibers were impregnated was 320 ° C.

The line speed was 1.5 m / min.

The fiber used is Hypertex fiberglass of 3B SE4535

The fiber content was 58% by volume.

The profile obtained is a plate with a width of 200mm and a thickness of 1mm.

The pultrusion head start-up protocol consists of using a single prepolymer to impregnate the fibers, until a stabilized speed is reached on the line. The second prepolymer is then introduced which is mixed at 320 ° C. with the first prepolymer, by means of a static mixer of the Sulzer type, just before their introduction into the pultrusion head.

At the outlet of the pultrusion head, 3 IR ovens of 2 m are placed in line which allow the resin to be post-polymerized in the molten state, at a temperature of 320 ° C. Taking into account the line speed of 1.5m / min, the polymerization time was 4mn. The final shaping of the plate is carried out by means of a cold shaper, regulated at 200 ° C., placed at the outlet of the last polymerization oven.

Results:

The absence of excessively large dead volumes in the pultrusion head allows the pultrusion process to continue for at least two hours without blocking, while the complete reaction time of the reactive composition at 320 ° C. is less than 5 minutes. The separation into layers of the fibrous reinforcement allows good impregnation of the fibers (see figure 7). In addition, the low viscosity of the prepolymers used also allows a pultrusion speed of 1.5 m / min, which is a factor in the productivity of this process.

Taking a sample of plate taken directly at the outlet of the pultrusion die made it possible to measure the molar mass of the resin at this stage of the process and the Mn found was 6200 g / mol (measurement made by NMR), this which confirms the fact that the polymerization in the pultrusion head is very partial, which accordingly limits the risks of overpressure and degradation of the fibers, or even of complete blockage of the pultrusion head.

The fact of using a reactive process makes it possible, after the post-polymerization step and passage through the last cold shaper, to obtain a composite having excellent mechanical properties: in this case, the bending is measured, according to the ISO standard 14125: 1998, a tensile strength> 1000 MPa (see table 1).

In addition, the fact of using a reactive chemistry made it possible to impregnate the fibers at high speed (ie above 1 m / min) at relatively low temperature (ie 320 ° C.). By way of comparison and to clearly show the interest of the invention, a polymer of mass equivalent to the mass obtained after post polymerization, should have been heated to more than 360 ° C to be sufficiently fluid to allow impregnation of the fibers by means of a non-reactive process. It would also have been necessary to have a very effective thermal stabilization to avoid its degradation, which remains complicated with PPAs. Finally, the cost of pultrusion equipment increases a lot above 330 ° C.

This reactive process is therefore compatible with reactive chemistry based on a high Tg polymer. [Table 1]

Example 5: Determination of the porosity rate the relative difference between theoretical density and experimental density (general method)

a) The data required are:

The density of the thermoplastic matrix

Fiber density

The basis weight of the reinforcement:

linear density (g / m) for example for a ¼ inch tape (from a single row)

mass per unit area (g / m ² ) e.g. for a wider tape or a fabric

b) Measures to be carried out:

The number of samples must be at least 30 so that the result is representative of the material studied.

The measures to be carried out are:

- The size of the samples taken:

Length (if linear density known).

Length and width (if mass per unit area known).

- The experimental density of the samples taken:

Mass measurements in air and water.

- The measurement of the fiber content is determined according to ISO 1172: 1999 or by analysis

thermogravimetric (ATG) as determined for example in document B. Benzler,

Applikationslabor, Mettler Toledo, Giesen, UserCom 1/2001.

The measurement of the carbon fiber content can be determined according to ISO 14127: 2008.

Determination of the theoretical mass fiber content: a) Determination of the theoretical mass fiber content:

With

ml the linear density of the tape,

L the length of the sample and

Meair the mass of the measured sample in air.

The variation in the mass rate of fibers is assumed to be directly related to a variation in the matrix rate without taking into account the variation in the quantity of fibers in the reinforcement. b) Determination of the theoretical density:

[Math 3]

1

d ^{th =} 1 ^~ % Mf _{th 1} % Mfth

d _m df

With dm and df the respective densities of the matrix and the fibers.

The theoretical density thus calculated is the accessible density if there is no porosity in the samples.

c) Evaluation of porosity:

Porosity is then the relative difference between theoretical density and experimental density.

Claims

1. A method of manufacturing at least one impregnated fibrous material comprising a fibrous material (or wicks) of continuous fibers and at least one thermoplastic polymer with a glass transition temperature Tg greater than or equal to 40 ° C, in particular greater than or equal to 80 ° C, preferably from 100 to 200 ° C, more preferably from 110 to 200 ° C, or a melting temperature Tf less than or equal to 400 ° C, in particular less than or equal to 350 ° C, in particular less or equal to 290 ° C, the glass transition temperature Tg and the melting temperature Tf being measured in DSC according to standard ISO 11357-2: 2013 and ISO 11357-3: 2013 respectively,

characterized in that said method comprises a step of impregnating in a pultrusion head with said at least one fibrous material by injection of a reactive composition in the molten state comprising at least one precursor of said thermoplastic polymer in the presence of said fibrous material,

said at least one fibrous material being during its entry into said pultrusion head divided in its thickness into n layers, in particular of substantially equal thicknesses, n being comprised from 2 to 20, in particular from 2 to 10, more particularly from 2 to 5, in particular equal to 4, each layer circulating in said pultrusion head in a channel which is specific to it, the injection of said reactive composition being carried out in each channel and / or between said layers during their reunification at the outlet of each channel,

said channel being heated to a temperature such that the reactive composition has an initial viscosity in the molten state of less than 50 Pa.s, more preferably less than 20 Pa.s, even more preferably less than 10 Pa.s, in particular less than 5 Pa.s, the viscosity in the molten state being measured by oscillatory rheology at a temperature Tf <T <Tf + 50 ° C for a semi-crystalline polymer or Tg + 220 ° C for an amorphous polymer, at 10 rad / dry under nitrogen scavenging with 5% deformation on a Physica MCR301 apparatus between two parallel planes 25 mm in diameter, the impregnation starting at the time of injection and ending before or after the reunification of said layers by superposition to form said at least one final impregnated fibrous material in which said precursors of said thermoplastic polymer are at least partially polymerized.

2. Method according to claim 1, characterized in that the maximum thickness e of each layer is such that the impregnation time of each layer is less than or equal to the time required for an increase in the number-average molecular mass (Mn ), determined by steric exclusion chromatography or by NMR, of the reactive composition in said layer, by a factor of 5, preferably by a factor of 3, in particular by a factor of 2.

3. Method according to one of claims 1 or 2, characterized in that the average residence time of the reactive composition in the head is at most equal to 3, preferably 2 and even more preferred 1.5 times the time of stay of said fibrous material.

4. Method according to one of claims 1 to 3, characterized in that the channels are cylindrical or not, in particular cylindrical.

5. Method according to claim 4, characterized in that the channels are cylindrical in shape, each channel having a thickness proportional to the thickness of each n layer, the thickness of each channel is between 2 and 3 times the thickness of each n layer, in particular between 1.5 and 2 times the thickness of each layer.

6. Method according to one of claims 1 to 5, characterized in that each channel is equipped with at least one contact zone having a radius of curvature greater than d / eps rupture (d / e), d being the diameter. fibers of the fibrous material and eps being the deformation at break of the fibers, placed alternately above or below the fibrous materials (rovings) during their journey through the impregnation head to cause and / or maintain a development of the fibrous material, optionally previously initiated upstream of the head, without damaging said fibrous material.

7. Method according to one of claims 1 to 4, characterized in that each channel is devoid of contact zones placed alternately above or below the fibrous materials (rovings) during their journey in the impregnation head , especially when the channels are conical in shape.

8. Method according to one of claims 1 to 7, characterized in that the injection of said reactive composition is carried out between two layers, two by two, at the outlet of said channels, said two layers then being impregnated to form a material. impregnated bilayer, each impregnated bilayer material then being assembled in its thickness with the others to form said final impregnated fibrous material.

9. Method according to one of claims 1 to 8, characterized in that said polymer

thermoplastic is a reactive prepolymer capable of reacting with itself or with another prepolymer, depending on the chain ends carried by said prepolymer, or else with a chain extender.

10. Method according to one of claims 1 to 9, characterized in that said at least thermoplastic polymer is selected from: poly (aryl etherketones) (PAEK), in particular poly (etheretherketone) (PEEK) and poly ( etherketoneketone) (PEKK); polyaryl sulfones, in particular polyphenylene sulfones (PPSU); polyarylsulphides, in particular

polyphenylene sulfides (PPS); polyamides (PA), in particular semi-aromatic polyamides (polyphthalamides) optionally modified by urea units; PEBAs, polyacrylates in particular polymethyl methacrylate (PMMA); polyolefins, in particular polypropylene, polylactic acid (PLA), polyvinyl alcohol (PVA), and fluoropolymers in particular polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE); and mixtures thereof, especially a mixture of PEKK and PEI, preferably from 90-10% by weight to 60-40% by weight, in particular from 90-10% by weight to 70-30% by weight.

11. Method according to one of claims 1 to 10, characterized in that said at least thermoplastic polymer is selected from polyamides, in particular aliphatic polyamides, cycloaliphatic polyamides and semi-aromatic polyamides (polyphthalamides), PVDF, PEEK, PEKK, PEI and a mixture of PEKK and PEI.

12. Method according to one of claims 1 to 11, characterized in that the rate of fibers in said impregnated fibrous material is from 45 to 80% by volume, preferably from 50 to 65% by volume, in particular from 54 to 65%.

13. Method according to one of claims 1 to 12, characterized in that the rate of porosity in said prepreg fibrous material is less than 10%, in particular less than 5%, in particular less than 2%.

14. Method according to one of claims 1 to 13, characterized in that it further comprises a step of shaping said wick or said parallel wicks of said impregnated fibrous material, by means of at least one calender. or a heating or cooling shaper, in the form of a single unidirectional strip or a plurality of parallel strips, or in in the form of a U-shaped or T-shaped section or in the form of a ring or of a plurality of unidirectional parallel strip rings, said shaping device being in contact or not with said impregnation head.

15. The method of claim 14, characterized in that the calendering or shaping step is carried out by means of a plurality of heating or cooling calenders, or heating or cold shapers mounted in parallel and / or in series with respect. in the direction of travel of the strands of fibers.

16. Method according to one of claims 14 or 15, characterized in that said (or said) heating calender (s) comprises (comprise) an integrated heating system by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous fillers in said thermoplastic polymer or mixture of thermoplastic polymers.

17. Method according to one of claims 1 to 16, characterized in that a belt press is present between the pultrusion head and the calender.

18. Method according to one of claims 1 to 17, characterized in that a series of post-polymerization ovens is present between the pultrusion head and the last shaper or the last calender.

19. Method according to one of claims 1 to 18, characterized in that said thermoplastic polymer further comprises carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably chosen from carbonaceous nanofillers, in particular graphenes. and / or carbon nanotubes and / or carbon nanofibrils or their mixtures.

20. Method according to one of claims 1 to 19, characterized in that said fibrous material comprises continuous fibers selected from carbon fibers, glass, silicon carbide, basalt-based, silica, natural fibers. in particular of flax or of hemp, of lignin, of bamboo, of sisal, of silk, or of cellulose, in particular of viscose, or amorphous thermoplastic fibers with a glass transition temperature Tg greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or greater than the Tm of said polymer or of said mixture of polymers when the latter is semi-crystalline, or the semi-crystalline thermoplastic fibers with a melting point Tf greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or greater than the Tm of said polymer or of said mixture of polymers when the latter is semi-crystalline, or a mixture of two or more of said fibers, preferably a mixture of carbon fibers, glass or silicon carbide, in particular carbon fibers.

21. Unidirectional tape of impregnated fibrous material, in particular tape wound on a spool, characterized in that it is obtained by a process as defined according to one of claims 14 to

20.

22. Tape according to claim 21, characterized in that the thermoplastic polymer is an aliphatic polyamide chosen PA 6, PA 11, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012, PA 11 / 1010 or PA 12/1010 or a semi-aromatic polyamide such as a PA MXD6 and a PA MXD10 or chosen from PA 6 / 6T, PA 6I / 6T, PA 66 / 6T, PA 11 / 10T, PA 5T / 10T, PA 11 / 5T / 10T, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 6T, PA BACT / 10T and PA BACT / 10T / 6T, PA BACT / 10T / 11, PA BACT / 6T / 11, PVDF, PEEK, PEKK and PEI or a mixture thereof.

23. Use of the method as defined according to one of claims 14 to 20, for the manufacture of calibrated ribbons suitable for the manufacture of three-dimensional composite parts, by automatic depositing of said ribbons by means of a robot.

24. Use of the tape of impregnated fibrous material, as defined in claim 21 or 22, in the manufacture of three-dimensional composite parts.

25. Use according to claim 23 or 24, characterized in that said manufacture of said composite parts relates to the fields of transport, in particular automotive, oil and gas, in particular offshore, gas storage, aeronautics, nautical, railway; renewable energies, in particular wind turbines, tidal turbines, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical and electronics.

26. Three-dimensional composite part, characterized in that it results from the use of at least one unidirectional strip of impregnated fibrous material as defined according to one of claims 21 to 22.