Method for preparing an impregnated fibrous material by reactive pultrusion

Patent metadata

Field	Value
Publication number	US-12359033-B2
Application number	US-202017624653-A
Country	US
Kind code	B2
Filing date	Jul 7, 2020
Priority date	Jul 9, 2019
Publication date	Jul 15, 2025
Grant date	Jul 15, 2025

Abstract

A method for manufacturing at least one impregnated fibrous material including a fibrous material made of continuous fibers and at least one thermoplastic polymer, the method including a step of impregnating the at least one fibrous material in a pultrusion head by injecting a reactive composition in the melt state including at least one precursor of the thermoplastic polymer in the presence of the fibrous material, the at least one fibrous material on entry into the pultrusion head being divided in its thickness into layers, with each layer circulating in its own channel within the pultrusion head, the reactive composition being injected into each channel and/or between the layers when they are recombined at the exit from each channel, the channel being heated, in which the precursors of the thermoplastic polymer are at least partly polymerized.

First claim

The invention claimed is:

1. A method for manufacturing at least one impregnated fibrous material comprising a fibrous material made of continuous fibers and a thermoplastic polymer having a glass transition temperature Tg more than or equal to 40° C., or a melting temperature Tm less than or equal to 400° C., the glass transition temperature Tg and the melting temperature Tm being measured by DSC according to standard ISO 11357-2:2013 and ISO 11357-3:2013, respectively,
wherein said method comprises a step of impregnating, in a pultrusion head, said fibrous material 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 fibrous material being, when it enters said pultrusion head, divided in its thickness into n layers, n being from 2 to 20,
each layer circulating in said pultrusion head in a channel that is specific to it,
said reactive composition being injected in each channel and/or between said layers when they are recombined at the exit from each channel,
said channel being heated to a temperature such that the reactive composition has an initial melt viscosity of less than 50 Pa·s, the melt viscosity being measured by oscillatory rheology at a temperature Tm≤T≤Tm+50° C. for a semi-crystalline polymer or Tg+220° C. for an amorphous polymer, at 10 rad/see under nitrogen flushing with 5% deformation on a rheometer apparatus between two parallel planes 25 mm in diameter, the impregnation starting at the moment of injection and ending before or after said layers are recombined by superposition to form said at least one impregnated fibrous material, in which said at least one precursor of said thermoplastic polymer is at least partly polymerized.

2. The method according to claim 1 , wherein 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 to increase the number-average molecular weight (Mn), determined by size exclusion chromatography or by NMR, of the reactive composition in said layer by a factor of 5.

3. The method according to claim 1 , wherein the mean residence time of the reactive composition in the pultrusion head is at most equal to 3 times the residence time of said fibrous material.

4. The method according to claim 1 , wherein the channels are cylindrical in shape.

5. The method according to claim 4 , wherein 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.

6. The method according to claim 1 , wherein each channel is fitted with at least one contact zone having a radius of curvature of greater than d/breaking eps (d/E), d being the diameter of the fibers of the fibrous material and eps being the deformation at break of the fibers, placed alternately above or below the fibrous material during the travel of the fibrous material in an impregnation head in order to cause and/or maintain spreading of the fibrous material, optionally initiated beforehand upstream of the impregnation head, without damaging said fibrous material.

7. The method according to claim 1 , wherein each channel is devoid of contact zones placed alternately above or below the fibrous material during the travel of the fibrous material in an impregnation head.

8. The method according to claim 1 , wherein said reactive composition is injected between two layers, in pairs, at the outlet of said channels, said two layers then being impregnated in order to form an impregnated bilayer material, each impregnated bilayer material subsequently being assembled in its thickness with others in order to form said at least one impregnated fibrous material.

9. The method according to claim 1 , wherein said thermoplastic polymer is a reactive pre-polymer capable of reacting with itself or with another pre-polymer, based on the chain ends borne by said reactive pre-polymer, or else with a chain extender.

10. The method according to claim 1 , wherein said thermoplastic polymer is selected from: polyaryl ether ketones (PAEK); polyaryl sulfones; polyarylsulfides; polyamides (PA); PEBAs, polyacrylates; polyolefins; and mixtures thereof.

11. The method according to claim 1 , wherein said thermoplastic polymer is selected from polyamides, PVDF, PEEK, PEKK, PEI and a PEKK and PEI mixture.

12. The method according to claim 1 , wherein a fiber level in said at least one impregnated fibrous material is from 45 to 80% by volume.

13. The method according to claim 1 , wherein a porosity level in a pre-impregnated fibrous material is less than 10%.

14. The method according to claim 1 , wherein it further comprises a step of shaping parallel strand(s) of said at least one impregnated fibrous material, by means of at least one calender or a heating or cooling forming machine, in the form of a single unidirectional ribbon or a plurality of parallel ribbons, or in the form of a U-shaped or T-shaped profiled element or in the form of a ring or of a plurality of parallel unidirectional ribbon rings, said heating or cooling forming machine being or not being in contact with an impregnation head.

15. The method according to claim 14 , wherein the shaping step is carried out using a plurality of heating or cooling calenders, or heating or cooling forming machines, mounted in parallel and/or in series with respect to the direction of passage of the parallel strands.

16. The method according to claim 14 , wherein the a plurality of heating or cooling calenders comprise a heating calender, wherein said heating calender comprise an integrated induction or microwave heating system, coupled with the presence of carbon-based fillers in said thermoplastic polymer.

17. The method according to claim 1 , wherein a belt press is present between the pultrusion head and a calender.

18. The method according to claim 1 , wherein a series of post-polymerization furnaces is present between the pultrusion head and a last forming machine or a last calender.

19. The method according to claim 1 , wherein said thermoplastic polymer further comprises carbon-based fillers.

20. The method according to claim 1 , wherein said fibrous material comprises continuous fibers selected from carbon, glass, silicon carbide, basalt-based or silica fibers, natural fibers, amorphous thermoplastic fibers where (a) when the thermoplastic polymer is amorphous, the amorphous thermoplastic fibers have a glass transition temperature Tg greater than the Tg of said thermoplastic polymer or (b) when the thermoplastic polymer is semi-crystalline, the amorphous thermoplastic fibers have a Tg greater than a melting temperature Tm of said thermoplastic polymer, semi-crystalline thermoplastic fibers wherein (a) when the thermoplastic polymer is amorphous, the semi-crystalline thermoplastic fibers have Tm greater than the Tg of said thermoplastic polymer or (b) when the thermoplastic polymer is semi-crystalline, the semi-crystalline thermoplastic fibers have a Tm greater than the Tm of said thermoplastic polymer, or a mixture of two or several of said continuous fibers.

Assignees

• Arkema France

Inventors

• Deyrail Yves
• Hochstetter Gilles
• Boucheres Thomas
• Causier Adrian

Classifications

• C08J2377/06

  Polyamides derived from polyamines and polycarboxylic acids (C08J2377/10 takes precedence) · CPC title

• C08J2300/22

  Thermoplastic resins · CPC title

• C08J5/24

  Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs · CPC title

• B29K2077/00

  Use of {PA, i.e.} polyamides, e.g. polyesteramides {or derivatives thereof}, as moulding material · CPC title

• B29C70/526

  Pultrusion dies, e.g. dies with moving or rotating parts (B29C70/523 takes precedence) · CPC title