METHOD FOR MANUFACTURING A FIBROUS MATERIAL WHICH IS MADE OF CONTINUOUS FIBRES AND IMPREGNATED WITH A THERMOPLASTIC POLYMER

Abstract

Impregnation of a fibrous material made from continuous fibres with a thermoplastic polymer matrix, the fibrous material comprising a thermoplastic sizing polymer and, before impregnation, an initial width. The method comprises an expansion step which is carried out by means of at least two tensioning members (E) and a heating system SC for heating the tensioning members and/or the fibrous material, the expansion being from 1.5 to 5 times the initial width. The expanded fibrous material is cooled below the Tg of the thermoplastic sizing polymer by means of a cooling system before being brought into contact with the thermoplastic polymer matrix.

Claims

1. A method for manufacturing an impregnated fibrous material comprising a fibrous material made of continuous fibres and at least one thermoplastic polymer matrix, characterized in that said fibrous material is sized by a sizing thermoplastic polymer and has, before its pre-impregnation with said thermoplastic polymer, an initial width I, said method comprising a step of spreading said fibrous material before a pre-impregnation step, said spreading step being carried out by means of at least two tension devices (E) and at least one heating system SC for heating said tension devices and/or said fibrous material, said spreading, after said fibrous material has passed in contact with said tension devices, being between 1.5 and 5 times the initial width I, said spread fibrous material being cooled below the Tg of the sizing thermoplastic polymer by means of a cooling system before it is placed in contact with said thermoplastic polymer matrix in the pre-impregnation system to carry out the pre-impregnation step, the spreading being consistent and always representing 1.5 to 5 times the initial width I when said fibrous material is placed in contact with said thermoplastic polymer matrix in the pre-impregnation system.

2. The method as claimed in claim 1, characterized in that the heating system SC and the at least two tension devices (E) are located outside or inside the pre-impregnation system.

3. The method as claimed in claim 1, characterized in that the heating system SC and the at least two tension devices (E) are located outside the pre-impregnation system and said pre-impregnation step is carried out with a system chosen from among a fluidized bed, spraying through a nozzle, aqueous dispersion and the molten route, in particular at high speed, in particular pre-impregnation is carried out in a fluidized bed.

4. The method as claimed in claim 1, characterized in that the heating system SC and the at least two tension devices (E) are located inside the pre-impregnation system and said pre-impregnation step is carried out with a system chosen from among a fluidized bed, spraying through a nozzle and aqueous dispersion, in particular pre-impregnation is carried out in a fluidized bed.

5. The method as claimed in claim 1, characterized in that said at least two tension devices (E) conduct heat and a heating means SC is present and integrated in said at least two tension devices (E).

6. The method as claimed in claim 1, characterized in that said at least two tension devices (E) conduct heat and a heating means SC is present above said at least two tension devices (E) for heating the fibrous material and said at least two tension devices (E).

7. The method as claimed in claim 5, characterized in that said at least two tension devices (E) conduct heat and a heating means SC1 is present and integrated in said at least two tension devices (E) and a heating means SC2 is present above said at least two tension devices (E) for heating the fibrous material and said at least two tension devices (E).

8. The method as claimed in claim 7, characterized in that at least one of the tension devices (E) may be cooled to control the temperature of the fibrous material.

9. The method as claimed in claim 1, characterized in that said at least two tension devices (E) do not conduct heat and a heating means SC2 is present above said at least two tension devices (E) for heating the fibrous material.

10. The method as claimed in claim 1, characterized in that the at least two tension devices (E) are compression rollers of convex, concave or cylindrical shape, preferably cylindrical.

11. The method as claimed in claim 10, characterized in that the number of rollers in contact with said fibrous material ranges from 2 to 20, in particular from 2 to 12, in particular from 2 to 9, preferably from 6 to 9.

12. The method as claimed in claim 10, characterized in that said compression rollers are in co-rotation and/or in counter-rotation.

13. The method as claimed in claim 10, characterized in that said compression rollers are vibrating.

14. The method as claimed in claim 10, characterized in that said compression rollers have a surface treatment and/or an apparent surface roughness minimizing friction with the reinforcing fibres.

15. The method as claimed in claim 10, characterized in that said rollers are separated from one another by a distance of less than 30 cm, in particular between D/2+1 mm and 30 cm, D being the diameter of the roller.

16. The method as claimed in claim 10, characterized in that the distance between the last roller and a point of contact between the reinforcing fibre and an element of the subsequent method is less than 30 cm.

17. The method as claimed in claim 1, characterized in that said thermoplastic polymer is a non-reactive thermoplastic polymer.

18. The method as claimed in claim 17, characterized in that it comprises a step of heating the pre-impregnated fibrous material to melt the thermoplastic polymer of the matrix and to finalize the impregnation of said fibrous material.

19. The method as claimed in claim 1, characterized in that said thermoplastic polymer of the matrix is a reactive prepolymer capable of reacting with itself or with another prepolymer, as a function of the chain ends borne by said prepolymer, or else with a chain extender.

20. The method as claimed in claim 19, characterized in that it comprises a step of heating the pre-impregnated fibrous material to melt and polymerize the thermoplastic prepolymer of the matrix optionally with said extender and to finalize the impregnation of said fibrous material.

21. The method as claimed in claim 1, characterized in that said at least one thermoplastic polymer of the matrix is selected from: poly(aryl ether ketone)s (PAEKs), in particular poly(ether ether ketone) (PEEK); poly(aryl ether ketone ketone)s (PAEKKs), in particular poly(ether ketone ketone) (PEKK); aromatic polyetherimides (PEIs); polyaryl sulphones, in particular polyphenylene sulphones (PPSUs); polyaryl sulphides, in particular polyphenylene sulphides (PPSs), polyamides (PAs), in particular semiaromatic polyamides (polyphthalamides) optionally modified by urea moieties; 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 blends thereof, especially a blend 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.

22. The method as claimed in claim 1, characterized in that said at least one thermoplastic polymer of the matrix is a polymer having a glass transition temperature such that Tg80 C., notably 100 C., in particular 120 C., notably 140 C., or a semicrystalline polymer having a melting temperature Tm150 C.

23. The method as claimed in claim 1, characterized in that said at least one thermoplastic polymer of the matrix is selected from polyamides, in particular aliphatic polyamides, cycloaliphatic polyamides and semiaromatic polyamides (polyphthalamides), PEKK, PEI and a blend of PEKK and PEI.

24. The method as claimed in claim 17, characterized in that the content of fibres in said impregnated fibrous material is from 45% to 65% by volume, preferably from 50% to 60% by volume, especially from 54% to 60%.

25. The method as claimed in claim 17, characterized in that the degree of porosity in said impregnated fibrous material is less than 10%, notably less than 5%, in particular less than 2%.

26. The method as claimed in claim 1, characterized in that said thermoplastic polymer of the matrix further comprises carbon-based fillers, in particular carbon black or carbon-based nanofillers, preferably chosen from carbon-based nanofillers, in particular graphenes and/or carbon nanotubes and/or carbon nanofibrils, or mixtures thereof.

27. The method as claimed in claim 1, characterized in that said fibrous material comprises continuous fibres selected from fibres of mineral origin, in particular carbon fibres, glass fibres, silicon carbide fibres, basalt-based or basalt fibres, silica fibres, natural fibres in particular flax or hemp fibres, lignin fibres, bamboo fibres, sisal fibres, silk fibres, or cellulose fibres in particular viscose fibres, or amorphous thermoplastic fibres having a glass transition temperature Tg above the Tg of said thermoplastic polymer of the matrix or of said blend of polymers when the latter is amorphous or above the Tm of said thermoplastic polymer of the matrix or of said blend of polymers when the latter is semicrystalline, or semicrystalline thermoplastic fibres having a melting temperature Tm above the Tg of said thermoplastic polymer of the matrix or of said blend of polymers when the latter is amorphous or above the Tm of said thermoplastic polymer of the matrix or of said blend of polymers when the latter is semicrystalline, or a mixture of two or more of said fibres, preferably a mixture of carbon, glass or silicon carbide fibres, in particular carbon fibres.

28. The use of the method as defined in claim 1, for the manufacture of calibrated tapes suitable for the manufacture of three-dimensional composite parts, by automated layup of said tapes using a robot.

29. The use as claimed in claim 28, characterized in that said composite parts relate to the fields of transport, in particular motor vehicle transport, of oil and gas, in particular offshore, of hydrogen, of gas storage, in particular hydrogen, aeronautical, nautical and railroad transport; of renewable energy, in particular wind turbine or marine turbine, energy storage devices, solar panels; thermal protection panels; sports and leisure, health and medical, and electronics.

30. A three-dimensional composite part, characterized in that it results from the use of the method as defined in claim 28.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0214] FIG. 1 presents a partial diagram of a unit for implementing the method for manufacturing a pre-impregnated fibrous material according to WO 2018/115736.

[0215] Each roving to be impregnated is unwound from a device 10 with reels 11 under the tension generated by rolls (not shown). The device 10 comprises a plurality of reels 11, each reel making it possible to unwind one roving to be impregnated. Thus, it is possible to impregnate several fibre rovings simultaneously. Each reel 11 is provided with a brake (not shown) so as to apply a tension to each fibre roving. In this case, an alignment module 12 makes it possible to position the fibre rovings parallel to one another. In this way, the fibre rovings cannot be in contact with one another, which makes it possible to prevent mechanical damage to the fibres in particular.

[0216] The fibre roving or parallel fibre rovings then pass into a tank 20 with a fluidized bed 22 provided with at least one tension device (E) (23), in particular a compression roller. The polymer powder is suspended in a gas G (air for example) introduced into the tank and flowing into the tank through a hopper 21. The roving(s) is (are) circulated through this fluidized bed 22.

[0217] FIG. 2 presents a tank comprising a fluidized bed provided with at least one tension device (E) which may be a compression roller.

[0218] FIG. 3 presents a fluidized bed tank comprising a tension device (E) on which the spread and heated fibrous material circulates to carry out the pre-impregnation, the spreading step being carried out outside the impregnation system and the heating system SC (30) is integrated in the compression rollers (E).

[0219] The fibrous material enters and exits the tank by passing over the edge of the tank (40) which may be a fixed or movable roller.

[0220] The figure shows two rollers but the invention is not limited to this configuration.

[0221] FIG. 4 presents a fluidized bed tank comprising a tension device (E) on which the spread and heated fibrous material circulates to carry out the pre-impregnation, the spreading step being carried out outside the impregnation system and the heating system SC (30), which may be an infrared system, is located above the compression rollers (E).

[0222] The fibrous material enters and exits the tank by passing over the edge of the tank (40) which may be a fixed or movable roller.

[0223] The figure shows two rollers but the invention is not limited to this configuration.

[0224] FIG. 5 presents a fluidized bed tank comprising a tension device (E) on which the spread and heated fibrous material circulates to carry out the pre-impregnation, the spreading step being carried out inside the impregnation system and the heating system SC (30) is integrated in the compression rollers (E), which are located above the fluidized bed.

[0225] The fibrous material enters and exits the tank by passing over the edge of the tank (40) which may be a fixed or movable roller.

[0226] The figure shows two rollers but the invention is not limited to this configuration.

[0227] FIG. 6 presents a fluidized bed tank comprising a tension device (E) on which the spread and heated fibrous material circulates to carry out the pre-impregnation, the spreading step being carried out inside the impregnation system and the heating system SC (30), which may be an infrared system, is located above the compression rollers (E), which are located above the fluidized bed.

[0228] The fibrous material enters and exits the tank by passing over the edge of the tank (40) which may be a fixed or movable roller.

[0229] The figure shows two rollers but the invention is not limited to this configuration.

[0230] FIG. 7 presents a system of six compression rollers (E) on two levels.

EXAMPLES

Comparative Example 1: Spreading Step Using Six Tension Devices (E) with No Heating System and Located Outside the Pre-Impregnation System

[0231] The following procedure was carried out:

[0232] A system of six smooth cylindrical rollers, distributed as shown in FIG. 7 in two rows of rollers, three being 25 mm in diameter in one row and three other rollers in another row being 20 mm in diameter.

[0233] The rollers have a Topocrom coating.

[0234] The system of rollers is located outside the tank.

[0235] The distance L between the two sets of upper and lower rollers is equal to 17 mm; the distance L between two adjacent rollers is equal to 15.2 mm and i=300 m (calculated by the equation shown in FIG. 7) thus inducing a gap between the rollers of 300 m for the passage of the roving.

[0236] Rovings used: SIGRAFIL T24-5.0/270-T140 from SGL Technologies GmbH, with a thermoplastic size.

[0237] Tension of the roving at the exit of the creel and before encountering the spreading system: 500 g

[0238] D50=108 m, (D10=39 m, D90=194 m) for the BACT/10T powder.

[0239] Edge of the tank equipped with a fixed roller 20 mm in diameter.

[0240] The first roller immersed in the fluidization tank is located 24 cm from the fixed roller at the tank inlet.

[0241] The width of the roving before and after the spreading system is measured using a Keyence LED measuring system. An equivalent system is positioned to measure the width of the roving at the fluidization bath inlet.

[0242] The data obtained are as follows:

TABLE-US-00001 TABLE 1 Width of the roving (mm) Inlet of the Outlet of the Fluidization system with six system with six tank Material tension devices tension devices inlet SIGRAFIL T24- 9-12 mm 15-18 mm 15-19 mm 5.0/270-T140, SGL Technologies GmbH, with a thermoplastic size

Comparative Example 2: Spreading Step Using an Infrared Heating System Located Outside the Pre-Impregnation System and with No Tension Devices (E)

[0243] The following procedure was carried out:

[0244] A linear shortwave infrared heating system (mono-radiant having a power of 3 kW maximum with power variator) is positioned horizontally outside the tank.

[0245] The fibre roving passes under the module at a distance of 5 cm from the emitter.

[0246] Rovings used: SIGRAFIL T24-5.0/270-T140 from SGL Technologies GmbH, with a thermoplastic size.

[0247] Tension of the roving at the exit of the creel and before passing under the infrared module: 500 g

[0248] D50=108 m, (D10=39 m, D90=194 m) for the BACT/10T powder.

[0249] Edge of the tank equipped with a fixed roller 20 mm in diameter.

[0250] The first roller immersed in the fluidization tank is located 24 cm from the fixed roller at the tank inlet.

[0251] The width of the roving before and after the IR heating system is measured using a Keyence LED measuring system. An equivalent system is positioned to measure the width of the roving at the fluidization bath inlet.

[0252] The data obtained are as follows:

TABLE-US-00002 TABLE 2 Width of the roving (mm) Inlet of the system Outlet of the system Fluidization with no tension with no tension tank Material devices devices inlet SIGRAFIL T24- 9-12 mm 10-12 mm 10-13 mm 5.0/270-T140, SGL Technologies GmbH, with a thermoplastic size

Example 3 (Invention): Spreading Step Using Six Tension Devices (E) with an IR Heating System Outside the Pre-Impregnation System

[0253] The following procedure was carried out:

[0254] A system of six smooth cylindrical rollers, distributed as shown in FIG. 7 in two rows of rollers, three being 25 mm in diameter in one row and three other rollers in another row being 20 mm in diameter.

[0255] The rollers have a Topocrom coating.

[0256] A linear shortwave infrared heating system (mono-radiant having a power of 3 kW maximum with power variator) positioned horizontally is placed above the system of tension devices outside the pre-impregnation system.

[0257] The fibre roving passes through the system of tension devices and thus under the module at a distance of 5 cm from the IR emitter.

[0258] The distance L between the two sets of upper and lower rollers is equal to 17 mm; the distance L between two adjacent rollers is equal to 15.2 mm and i=300 m (calculated by the equation shown in FIG. 7) thus inducing a gap between the rollers of 300 m for the passage of the roving.

[0259] Edge of the tank equipped with a fixed roller 20 mm in diameter.

[0260] Tension of the roving after contact with the tank inlet roller 20 mm in diameter and before encountering the spreading system located in the tank: 500 g The width of the roving before and after the spreading system is measured using a Keyence LED measuring system. An equivalent system is positioned to measure the width of the roving at the fluidization bath inlet.

[0261] Rovings used: SIGRAFIL T24-5.0/270-T140 from SGL Technologies GmbH, with a thermoplastic size.

[0262] D50=108 m, (D10=39 m, D90=194 m) for the BACT/10T powder.

[0263] The data obtained are as follows:

TABLE-US-00003 TABLE 3 Width of the roving (mm) Inlet of the system Outlet of the system with six tension with six tension Fluidized devices with devices bed Material heating with heating inlet SIGRAFIL T24- 9-12 mm 26-30 mm 27-30 mm 5.0/270-T140, SGL Technologies GmbH, with a thermoplastic size

Example 4 (Invention): Spreading Step Using Six Tension Devices (E) with an IR Heating System Inside the Impregnation System Above the Fluidized Bed

[0264] The following procedure was carried out:

[0265] A system of six smooth cylindrical rollers, distributed as shown in FIG. 7 in two rows of rollers, three being 25 mm in diameter in one row and three other rollers in another row being 20 mm in diameter.

[0266] The rollers have a Topocrom coating.

[0267] A linear shortwave infrared heating system (mono-radiant having a power of 3 kW maximum with power variator) positioned horizontally is placed above the system of tension devices.

[0268] The fibre roving passes through the system of tension devices and thus under the module at a distance of 5 cm from the IR emitter.

[0269] The system with tension device rollers and associated heating is located in the tank.

[0270] The distance L between the two sets of upper and lower rollers is equal to 17 mm; the distance L between two adjacent rollers is equal to 15.2 mm and i=300 m (calculated by the equation given in [Math 2]) thus inducing a gap between the rollers of 300 m for the passage of the roving.

[0271] Edge of the tank equipped with a fixed roller 20 mm in diameter.

[0272] Tension of the roving after contact with the tank inlet roller 20 mm in diameter and before encountering the spreading system located in the tank: 500 g The first roller immersed in the fluidization tank is located 16 cm from the last roller of the spreading system.

[0273] The width of the roving before and after the spreading system is measured using a Keyence LED measuring system. An equivalent system is positioned to measure the width of the roving at the fluidization bath inlet.

[0274] Rovings used: SIGRAFIL T24-5.0/270-T140 from SGL Technologies GmbH, with a thermoplastic size.

[0275] D50=108 m, (D10=39 m, D90=194 m) for the BACT/10T powder.

[0276] The data obtained are as follows:

TABLE-US-00004 TABLE 4 Width of the roving (mm) Inlet of the system Outlet of the system with six tension with six tension Fluidized devices with devices bed Material heating with heating inlet SIGRAFIL T24- 9-12 mm 26-30 mm 27-30 mm 5.0/270-T140, SGL Technologies GmbH, with a thermoplastic size