WO2020074789A1

WO2020074789A1 - Crack-resistant thermosetting pre-impregnated tape

Info

Publication number: WO2020074789A1
Application number: PCT/FR2018/000235
Authority: WO
Inventors: Max Sardou; Patricia SARDOU
Original assignee: Max Sardou; Sardou Patricia
Priority date: 2018-10-09
Filing date: 2018-10-09
Publication date: 2020-04-16

Abstract

The present invention relates to preimpregnated composites of coldpreg and prepreg type and in particular the method for producing these preimpregnated composites for applications intended for highly stressed composite structures, namely all the following applications : astronautics, aeronautics, sailing, transport, industry, wind power, leisure. The contribution of the present invention is to enable a perfect impregnation at high speed by producing tapes FB of perfectly aligned fibers F, without excess resin, without segregation with very low bubble content, and above all by producing fine fibers and by placing them in such a way that they make crack propagation virtually impossible; such tapes considerably improve the interlaminar shear strength (ILSS) properties, they increase the resistance of the material to sudden crack propagation (K1c) and the energy necessary for creating a crack (G1c).

Description

ANTI-CRACK THERMOSETTING PREPREGNE TAPE

Technical sector:

The present invention relates to thermosetting composites prepregs of the coldpreg and prepreg type and in particular to the process for producing these prepreg composites for applications intended for highly stressed composite structures, namely: torsion springs, coil springs, leaf springs , the ground connection elements for the automobile, the engine cradles, the sub-chassis, the high-pressure tanks, the wind turbine blades, the electrical insulators, the structures and blades of airplanes, helicopters, structural components, or no, planes, boats, land vehicles, industrial or leisure components; that is to say all applications: Astronautics, Aeronautics, Marine, Transport, Industry, Wind, Leisure, as well as composite elements such as bars, beams, hulls, etc.

The present invention relates to devices for prepreging at least one fiber with a fluid.

In the rest of the text, resin is used to denote: a material

polymerizable (epoxy example, EPOSIL subject of PCT F.1487 from Dr.

SARDOU, polyester, vinylester etc.) or one of the components of a polycrystallisable (thermosetting) ceramic slip (example: geopolymer, Toughceram subject to PCT FR 16/000140 by Dr SARDOU) or the like.

The "prepregs" and the "coldpregs" are semi-finished products consisting of a resin mixed, in optimized proportions, with a hardener or the like (resin more hardener are also called matrix), impregnating a reinforcement, said products are kept at low temperature in a cold room to avoid complete polymerization.

Examples of reinforcement structure: non-woven, mat, fabric, braid, fiber. Example of reinforcing materials: glass, carbon, silica, silicon carbide, aramid, boron, basalt. The prepreg composite (matrix plus reinforcement) thus formed is intended, after leaving the cold room, for molding preferably hot and under pressure so as to manufacture a finished product.

Note: geopolymers and certain ceramics, include a multi-component system analogous to a resin and a hardener, they constitute a crystallizable matrix.

They can impregnate reinforcing fibers by the same process as organic resins and be treated like conventional organic polymers.

State of the art:

It is known that the industrial production of composite products based on fibers, in particular carbon, requires a very large number of fibers and that the perfect coating of these fibers poses problems and in particular requires a very low viscosity of the resin mixture more hardener. during impregnation.

Commercial prepregs require:

• Either the use of a solvent (acetone, ethanol, water etc.) to thin the hardening resin mixture and facilitate the impregnation of the reinforcement; after the impregnation operation, it is then necessary to evaporate the solvent, in an oven, which cannot be carried out perfectly, poses pollution problems (VOC = volatile organic compounds), requires complex, costly installations , non-explosive (ATEX) and consumes a significant amount of energy and separating films.

• Either the use of so-called hot melt high-viscosity matrices (hotmelt), these matrices use long-chain molecules which pose steric problems when it is desired to additivate them with mineral resins of the EPOSIL type.

Conventional systems have the disadvantage of low

productivity, a high rate of air trapped in the finished product, alignment mediocre fibers, these systems use an excess of resin which allows to realign the fibers and to expel the air during the compression of the parts. This exercise means that there is a large excess of (expensive) resin which is sacrificed and lost during the implementation!

In fact, there are currently no industrial devices which respond to the problem of high quality coating at low cost and at high speed, in particular simultaneous, of numerous fibers for the mass production of composite elements.

A big problem is the presence in large quantity of microbubbles, trapped in the impregnated matrix. These bubbles are brought into the matrix, by the fibers, to which they are adsorbed, during

impregnation. These bubbles degrade the mechanical properties of the finished products in which they are disseminated.

The fibers (F) are generally poorly controlled and ribbons (Fb) are obtained having, seen in section, the appearance presented in FIG. 2. With LR width of the ribbon and ER thickness of said ribbon. It is noted that there are in this type of ribbon, zones rich in matrix M, which are conducive to the propagation of cracks (if said cracks are directed in the direction ER or the direction LR.)

Analysis of previous patents:

a) In certain wire placement devices, in the wet, such as

multi-plate high-speed filament winding, patented by SARDOU SAS, (W02005028189 A1) and intended for the manufacture of rods for coil springs and composite torsion springs or for the manufacture of high-pressure composite tanks, difficulty keeping the reels of "dry" rovings when the platters rotate at high speed. Indeed these have the annoying tendency to unwind under strong centrifugal acceleration. The “tack” (adhesion, tackiness) of the size of the dry fibers is not sufficient to combat centrifugal force. Another problem is the difficulty of placing dry fibers, or wet fibers, when the tension applied to the fibers tends to slide said fibers. This problem is typical when making pressure tanks; he it is in fact impossible to produce the reinforcement belt beyond the cylindrical part of the bottle; the cylinder-dome connection zone is a critical zone because it is not reinforced while undergoing stresses requiring such reinforcement! finally, if the tension of the fibers is not perfectly controlled there is a high risk of segregation of said fibers which come to rest on the fibers of the outer layer and leave a thick layer of pure resin near the surface.

b) Patent EP 2589475A1 by TORAY INDUSTRIE (jp) describes a process intended to produce semi-thermoplastic fiber-reinforced products, using fiber ribbons impregnated in a horizontal transfer mold. The patent mentions a fiber tracanage treatment by fiber before any other treatment. Spreading the fibers before any additional treatment is bad for the quality of the opening of the fibers and for the compactness of the assembly. Constitute a ribbon before penetration into the impregnation means resulting in a lack of control over the relative position of the fibers in the finished product. Because forcing a thermoplastic, which by its nature is extremely viscous through the layers of fibers is bad for the boiling of the product and for the control of the placement of the fibers relative to each other, there is a high risk of packing (segregation) .

c) Patent FR 3017818A1 by Patricia & Max SARDOU describes a process for impregnating a single fiber at high speed and preferably under vacuum to ensure its perfect debubbling.

Contribution of the invention:

The use of reels of prepreg ribbons to manufacture rods as described in patent FR 1502526 by Dr SARDOU, makes it possible: to eliminate the pitfall of unwinding and considerably increase the simplicity, reliability and speed of the unit multi-platform production (equipped with rovings) mentioned above. In the case of pressure tanks, only a prepreg fiber, thanks to its "tack", can be placed in the cylinder-dome connection zone without slipping. The contribution of the present invention is to allow perfect impregnation at high speed by producing Fb ribbons of F fibers perfectly aligned, without excess resin, perfectly distributed, without segregation, at very low bubble rate, and above all by producing fine fibers and placing them in such a way as to make it almost impossible to propagate cracks; such tapes considerably improve the interlaminar shear properties (ILSS), they increase the resistance of the material to the brutal propagation of cracks (K1 c) and the energy

necessary to create a surface (G1 c).

It is underlined that within the meaning of the present description, by “coating”, or impregnation is meant the fact of coating and / or covering and / or soaking and / or moistening, etc., a reinforcement with a given fluid, with the further aim of obtaining the impregnation of this reinforcement with this fluid, that is to say the intimate penetration of the fluid into this fibrous reinforcement so as to perfectly "wet" all of the fibrils of said reinforcement.

Also, the present invention aims to achieve a device for coating at least one fiber or the like, preferably a plurality of fibers, which meets the needs mentioned above, for an industrial production of perfectly composite elements saints, and which is also relatively simple and easy to use.

Note Figure 1 shows a machine for producing an impregnated tape according to the invention. In order not to unnecessarily overload the drawing; said machine produces a ribbon consisting of only one layer C1 composed of two layers: St, S’t. It is, of course, possible to produce ribbons made up of a very large number of C1-type layers.

Notation: an apostrophe is placed for the items at the bottom example 3A = upper fibers and 3Ά = analogous lower fiber.

Other characteristics and advantages of the present invention will appear during the following description given with reference to the drawings annexed by way of illustration but in no way limitative, in which:

Figures 1 & 4: 1 (1A & 1 B) preferably clamping in materials with a high coefficient of friction such as stainless steel, consisting of bars, or knives with rounded point, having a radius of curvature, in the friction zone, between 1.5 and 15 mm, located upstream or preferably in the oven area 5

2 (2A & 2B) reel (s) of fibers, of reinforcement with central or better peripheral unwinding

3 (3A & 3Ά) independent fibers from type (2A &

2B)

4 (3Ba & 3’Ba) stretched fibers

5 (3C & 3’C) fibers "open in a fine sheet" by type tie

(1A & 1 B) & (1 Ά & 1’B)

6 (4a & 4’a) means for placing fibers of type (3A & 3Ά)

7 (4b & 4'b) means of flattening and at a determined distance the fibers of type (3A & 3Ά) so that they are tangent (contiguous) to each other once "open" and refined by the mooring so to form a fine, continuous sheet called "layer or sheet".

8 (5) fiber drying and heating oven this oven is

preferably regulated at a temperature included, depending on the fiber to be treated between 100 and 180 ° C. A glass fiber is treated around 1 15 ° C

9 (6 & 6 ') means of control, at the inlet of the well (7), of the sheets (St &S't, etc.) of fibers at the outlet of the oven (5) the combination of means of type: 6, 6 ', 6 ”, 6 etc., these said means, of the type (6 etc.) make it possible to provide sufficient spacing between the sheets to ensure perfect impregnation of each sheet when it enters the matrix. The sheets gradually converge between them while traveling in the matrix, towards the outlet, located at the base of the well, so as to obtain perfectly superimposed layers at the outlet of the well (7). It should be noted that the fibers constituting the sheets are at high temperature relative to the matrix, during the penetration of said fibers into said matrix, an extremely fluid boundary layer is therefore locally created. matrix of superheated matrix, which penetrates and impregnates the fibers all the more easily when the sheet is extremely fine and perfectly ordered; concomitantly, a powerful bubbling takes place, which makes it possible to obtain ribbons without bubbles. It should be borne in mind that the viscosity of a matrix decreases very sharply when the temperature increases.

10 (7) known means of ‘home of the art’, permitting the impregnation of fibers (s) of type (3C). In the example illustrated, this is a vertical well, containing the impregnation fluid (7a), this well is preferably regulated at a temperature comprised, between the matrix to be treated, between 10 and 180 ° C. A DGEBA can be used, depending on the hardener used between 20 and 90 ° C. A roller or belt system offering an equivalent geometry and possibility of converging layers is part of the concept we are claiming.

11 (7a) impregnation fluid

12 (7b) the level of the fluid is kept constant by means of a level sensor and an arrival, via the tube (7b), of an intimate mixture of more hardening resin forming the matrix.

13 (8) mechanism for calibrating the outlet section, 7c, of the impregnation well (7) through which the tape 14a passes

14 (9) optional means known to those skilled in the art, called tunnel

rapid heating; in the example illustrated it is a tunnel oven, preferably microwave. This tunnel (9) is heated using, for example, klystrons (9A). In this channel (9) travels and partially polymerizes the ribbon matrix, (14b)

15 (10) optional means known to those skilled in the art, called tunnel

fast freezing ; in the example illustrated, it is a channel in which the ribbon (14c) circulates. This channel (10) is cooled using, for example, a refrigerant, it can be cold air, nitrogen or C02 at boiling temperature, respectively minus 196 ° C & 56.6 ° C. 16 (11) optional means for measuring the thickness of the tape (14d) placed at the outlet of the impregnation machine, this measuring means, coupled to an automaton, controlled in a closed loop, controls the mechanism (8) and optionally allows precise adjustment of the geometry of the ribbon produced, by modifying the outlet section 7c of the well 7

17 (12) means of heating the oven, it may be radiant

infrared, heating resistors or klystrons

18 (13 & 13 ’) optional means for homogenizing the oven temperature (5) this means contributes to the bursting of the fibers in the form of a sheet.

19 (14a) tape at the end of impregnation

20 (14b) ribbon heated by (9) and in the course of partial polymerization

21 (14c) ribbon cooled in tunnel 10

22 (14d) tape at the outlet of the impregnation machine measured by the

sensor 11.

Figures 2 & 3:

1. (Fb) FB tape

2. (M) area of the matrix-rich Fb ribbon

3. (F) F fibers

4. (LR) width of Fb tape

5. (ER) thickness of the tape Fb

6. (3C1, 3C2, 3C3, 3C4) fine and wide fibers, example of a complete sheet St, formed of contiguous fibers constituting the upper half of the layer C1

7. (3’C2, 3Ό3, 3’C4) example of a partial ply S’t constituting the lower half of the layer C1 and optionally comprising one fiber less than the ply St

8. (3'C1, 3Ό5) example of optional additional S't ply preferably using fine fibers with a grammage (TEX) half that used by the fibers (3'C2, 3'C3, 3'C4) completing the lower half of layer C1

9. (C1, C2, C3) example of stacking of type C layers constituting an Fb prepreg tape Description of the Process

More specifically, the subject of the present invention is a device for coating at least one fiber or the like with a fluid, which comprises:

• one or more spool (s) of fibers (2A, 2B etc.), each delivering a roving (3A & 3Ά)

• one or more means (s) for guiding (4a & 4’a) rovings of type 3A upper family and 3Ά lower family preferably it is ceramic rings or the like coupled or not with means controlling the tension of rovings

· One or more means (s) for spacing the wires (4b & 4'b) of rovings of type 3A & 3Ά, preferably these are ceramic or similar combs controlling the position and especially the spacing between the rovings d '' the same tablecloth

• one or more means (1A, 1 B) and (1Ά, 1'B), known to those skilled in the art, ensuring the "flattening of the roving", that is to say operating the modification of the shape of the filaments of said rovings, for example of the type (3Ba) so that they become thinner taking the shape 3Ci with “i” number of the rovel considered, the so-called rovings, neighboring and flattened, then form a continuous sheet ( 3C1, 3C2, 3C3, 3C4 etc.) extremely fine and wide, called ply, St as presented in FIG. 3 (upper part of layer C1) such a ply, thanks to its extreme fineness facilitates impregnation.

• one or more heating means (12 & 12 ’) of the rovings ensuring the dehydration and the optimal heating of said rovings.

· A means of impregnation (7) of the rovings of St roving

(3C1, 3C2, 3C3, 3C4 etc.) and S't (3'C1, 3'C2, 3'C3, 3'C4, 3'C5, etc.) preferably constituted by a "well"; the temperature of the impregnation fluid (7a), which the well contains is regulated, between 10 and 180 ° C., the depth of said well, is calculated so that, for a given speed of the sheets, a wetting time is obtained fibers of approximately one second, this in order to guarantee a perfect impregnation and a defoaming appearance of the roving plies in the impregnation fluid (7a). The hydrostatic pressure, within the matrix, ensures the evacuation of bubbles towards the top of the well.

• several means (6 & 6 ') of setting up the layers of St roving (3C1, 3C2, 3C3, 3C4 etc.) and S't (3'C1, 3'C2, 3'C3, 3 'C4, 3'C5, etc.) ensuring perfect control of the separation of the plies during their penetration into impregnating fluid (7a), so that the plies are perfectly accessible on both sides by said fluid.

• an adjustable calibration 7c located at the base of the well whose geometry ensures that the ribbon 14a is set to the "correct" thickness. the geometry of the ribbon thus produced results in perfect mastery of the ratio of fiber to matrix rate. The layers converge towards each other, from the means (6 & 6 ’) and are contiguous when arriving at the output calibration 7c which constitutes the lower part of the well. This calibration 7c is controlled in a closed loop by measuring the thickness of the tape 14d at the outlet of the impregnation machine, a mechanism 8 ensures the adjustment of the calibration.

• one or more source (s) of this fluid (7b) capable of delivering this fluid (8) in at least one impregnation means (7), this source regulating the supply of fluid (8) so as to maintain a constant level of the fluid (7a) in the impregnation means (7).

Thanks to this process, we perfectly master:

• The geometry of the ribbon;

• The shape, position, straightness of the fibers inside said ribbon;

• The rate of residual bubbles

• The matrix fiber ratio,

A high precision of the parts produced is therefore obtained and a minimum loss of resin during implementation.

It is specified that the figures essentially represent an embodiment of the object according to the invention, but that there may be other embodiments which meet the definition of this invention. It is further specified that, when, according to the definition of the invention, the object of the invention comprises “at least one” element having a given function, the embodiment described may include several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated comprises several elements of identical function and if, in the description, it is not specified that the object according to this invention must necessarily include a number particular of these elements, the subject of the invention could be defined as comprising “at least one” of these elements.

It is finally specified that when, in the present description, an expression alone defines, without any specific mention relating to it, a set of structural characteristics, these

characteristics may be taken, for the definition of the object of protection requested, when this is technically possible, either separately or in total and / or partial combination.

It is likewise specified that, in the present description, if the adverb "substantially" is associated with a qualifier of a given means, this qualifier must be understood in the strict sense or approximated.

In the embodiment described above, the device according to the invention only comprises an impregnation means (7) with its calibration (7c). It is understood, however, that, in particular to arrive more quickly at substantial production, of the present invention, the device may include a plurality of impregnation means (7) with their calibration (7c). All substantially identical to the first impregnation means (7) with its calibration (7c) described above.

Referring to FIG. (1), the present invention relates to a device for coating at least: a fiber or a ribbon of fibers or a fabric or the like, composed of glass fiber, basic carbon or the like, with a fluid, advantageously viscous, for example a polymerizable organic resin, a mineral resin, a geopolymer, a ceramic slip, or the like.

By "fiber", within the meaning of the present description, is understood an oblong filiform body composed of a single strand or of a plurality of strands (fibrils) associated with each other in any way possible, such as commercially available glass fibers. For example a glass roving is a fiber made up of thousands of fibrils, typically 18 microns in diameter.

It should be noted that, during the operation of the device:

When the fibers are of the multi-strand type (a multi-strand glass fiber can comprise approximately 1800 strands (or fibrils)), passing over the means (1B, 1A), they “open, become thinner”, as defined above. before, and when they pass through the impregnation means (7) all their strands are then well coated. If the fibers have been brought into the oven (5) at a temperature of for example 100 to 120 ° C, when they penetrate into the resin (8), which is at a temperature t1 for example typically between 20 and 50 ° C, the temperature differential locally lowers the viscosity of the resin and promotes the impregnation of the fibers.

From the description given above, as a whole, it becomes clear that the device according to the invention makes it possible to achieve the aims mentioned in the preamble, as well as others which are also of some importance.

Note :

By oblong body is meant one or more fibers, a fabric or the like (3a)

One can, optionally, place a heating means between the calibration (7c) and the freezing means (10) so as to "advance" the polymerization of the impregnation matrix to a stage called "beta" where that -this becomes more viscous. The purpose of this procedure is to limit the viscosity kiss during the rise in temperature of the fluid.

impregnation, during the final polymerization, and therefore to minimize the fluid leakage, this fluid leakage being called the "flow".

To avoid this heat treatment, which consists in starting the polymerization, then in stopping it, as soon as the viscosity of the matrix is deemed sufficient, an elegant solution consists in using an EPOSIL resin.

An EPOSIL resin is a compound of organic resin, preferably a DGEBA, and of dendritic mineral resin. Resin mineral gives thixotropy to the system. The dendritic mineral resin plays the role of micro staples and improves all the mechanical properties of the matrix, starting with its resistance to fatigue and its tolerance to damage.

A conventional hardener can advantageously be used with an EPOSIL resin.

The advantage presented by EPOSIL is that it allows to precisely control and adjust the viscosity and therefore the "flow" of the matrix during polymerization. It suffices to play on the proportion of mineral resin compared to organic resin.

Advantageously, only the means of

cooling 10 and not using the heating means 9 to obtain what we call a coldpreg tape, that is to say a tape having a tack similar to a prepreg while having a capacity of

repositioning. A moderately cooled coldpreg tape is advantageously implemented immediately after its production, which has many logistical advantages, the impregnation machine being located upstream from the production line for composite parts.

By roving is meant a fiber made up of independent fibrils more or less parallel to each other obtained by direct assembly, that is to say without "twisting" or "twisting". The English designate this roving by: Continuous Tow or by direct roving.

In summary :

Method for producing prepreg tapes, made up of reinforcing fibers impregnated with matrix, said tapes being intended in particular for producing leaf springs, torsion springs, helical springs, pressure tanks, said method is original by the has the following eleven steps:

• Stage 1 we exclusively choose ribbons spools, that is to say spools of fiber made up of independent fibrils more or less parallel to each other obtained by direct assembly, ie without "twisting", or "twisting"

• Stage 2 preparation of several coils each supplying a fiber

• Step 3 installation of means controlling the tension of the fibers and grouping them into a multitude of bundles of distinct fibers, using control means constituted by one of the following solutions: holes made in guide plates, ceramic guides (4'a)

• Step 4 preparation of a multitude of layers of distinct fibers, originating from the upstream fiber bundles, by placing them in parallel, with precision, using spacing means (4'b) constituted by one of the following solutions : holes made in guide plates, combs, or ceramic guides, this spacing is adjusted so that the fibers of the same sheet are tangent to each other at the end of the next step 7 · Step 5 in the plane of the plies, adjustment, of the lateral position of the fibers constituting the different plies, relative to each other, the different plies being intended to be superimposed on each other, at this stage one of the solutions can be used following:

o either the fibers are all of identical tex (grammage), and therefore of identical width, once thinned in step 7, in which case they will overlap exactly, each fiber elementary, of a tablecloth, being superimposed on its counterpart of the neighboring tablecloth,

o or by the fact that, for a layer, for example of the C1 type, the neighboring S't type sheet, comprise at each of its ends fibers having a half grammage, compared to the standard grammage of the other fibers, other fibers which make up the two so-called St and S't sheets and that, in addition, the S't sheet has a fiber with a standard grammage less than the St sheet, so that once the elementary fibers which make up the two sheets are superimposed are placed in staggered rows, (such an arrangement improves the resistance to crack propagation)

• Step 6 penetration into a furnace 5 of said layers

• Step 7 thinning of the fibers, of each layer, with the implementation for each of a dedicated tie, consisting of means such as bars 1A and 1B whose diameter is between 2 and 20 mm, at this stage the fibers are thinned and widened, so that they are tangent laterally, each ply of fibers, then forms a ply, of fine fibers and uniform over the entire width of said ply (called St)

• Step 8 heating the sheets, in the oven 5 at a temperature between 80 ° C and 130 ° C.

• Step 9 by means of a dynamic mixing tube arriving at 7b from the thermosetting matrix 7a, filling the well 7 and maintaining level, thanks to a level detector, the temperature of the matrix in the well (7) being regulated at a temperature between 10 ° C and 50 ° C.

• Step 10 placing the multiple St-type plies in precise position by tethers arranged at the outlet of the furnace 5 so that all the plies are perfectly separated from one another when they penetrate into the well 7, thanks to their heat, due to the passage through the oven 5, the sheets when they penetrate into the resin, are surrounded by a boundary layer of hot resin this resin is therefore locally extremely fluid, thanks to the thinness of the sheets the fluidized resin very easily penetrates said sheets permeating perfectly and causing perfect bubbling of said layers

• Step 1 1 the plies gradually descend into the well 7 and gradually converge towards the lower outlet 7c, of said well, the plies gradually approach and then stack against each other to form a ribbon 14a, inside and near the lower exit of well 7

Original method by the fact that the ribbon produced can include both an even number and an odd number of layers

Original method by the fact that the thickness ER of the tape 14a is adjusted by means 8 which regulates the outlet dimensions of the outlet calibration of the well 7, as a function of the dimensions of the said tape 14d measured by a sensor 11

Original method by the fact that it can be completed with one of the following three solutions:

o By the fact that a heating means 9 is placed at the outlet of the well 7

o By the fact that a cooling means 10 is placed at the outlet of the well 7

o By the fact that a heating means 9 is placed at the outlet of the well 7 and is followed by a cooling means 10

Original method by the fact that the thermosetting matrix can be based on epoxy, vinylester, polyester, ceramic slip

Original process by the fact that the fiber used, or roving, can be carbon fiber, glass, aramid, basalt, ceramic fibers.

Claims

1. Method for producing prepreg tapes, consisting of reinforcing fibers impregnated with thermosetting matrix, said tapes being intended in particular for the production of leaf springs, torsion springs, helical springs, pressure tanks, parts of structure, said process comprises the following ten steps:

• Step 1: We choose exclusively rovel spools, that is to say spools of fiber made up of independent fibrils more or less parallel to each other obtained by direct assembly, that is to say without "twisting", or "twisting "

• Step 2: Preparation of several coils each providing a fiber

Step 3: Installation of means controlling the tension of the fibers and grouping them into a multitude of bundles of distinct fibers, using control means constituted by one of the following solutions: holes made in guide plates, or ceramic guides (4'a)

· Step 4: Preparation of a multitude of layers of distinct fibers, originating from the upstream fiber bundles, by placing them in parallel, with precision, by means of spacing means (4′b) constituted by: holes made in guide plates, combs, or ceramic guides, this spacing is adjusted so that the fibers of the same ply are tangent to each other at the end of the following step 8

• Step 5: In the plane of the plies, adjustment of the lateral position of the fibers constituting the different plies, relative to each other, the different plies being intended to be superimposed on each other.

• Step 6: Penetration of said layers in an oven (5), the oven having a regulated temperature between 80 ° C and 130 ° C • Step 7: By means of a dynamic mixing tube (7b) arrival of the thermosetting matrix (7a), so as to ensure the

filling the well (7) and keeping it level, thanks to a level detector, the temperature of the matrix in the well (7) being regulated at a temperature of between 10 ° C. and 50 ° C. The said method is characterized by the following 3 steps:

Step 8: Thinning of the fibers of each ply, with the implementation for each of a dedicated tie, consisting of means such as bars (1A) and (1B) whose diameter is between 2 and 20 mm, at this stage the fibers are thinned and widened, so that they become tangent laterally, each layer of fibers then forms a continuous layer of fine and uniform fibers over the entire width of said layer (called St and S't)

• Step 9: Precise positioning of multiple layers (of type St and

S’t) by fittings (6 ’and 6) arranged at the outlet of the oven (5) so that all the sheets are perfectly separated from one another when they penetrate into the well (7); thanks to their heat, due to the passage through the oven (5), when they penetrate the resin, the sheets are surrounded by a "boundary layer" of hot resin, this resin is therefore locally extremely fluid; thanks to the fineness of the plies, the fluidized resin very easily penetrates said plies, permeating them perfectly and causing a perfect boiling of said plies

• Step 10: The sheets gradually descend into the well (7) and gradually converge towards the lower outlet (7c), of said well, the sheets gradually approach, then stack against each other to form a ribbon (14a) , inside and near the lower outlet of the well (7) which plays the role of calibration.

2. Method according to claim 1 characterized in that in step 5 the fibers of all the sheets are all of identical tex (grammage), and therefore of identical width, once thinned in step 8, in which case they will be superimposed exactly, each elementary fiber, of a layer, being superimposed on its counterpart of the neighboring layer.

3. Method according to claim 1 characterized in that in step 5 for a pair of layers of the multitude of layers, the layer [S't], close to [St], has at each of its ends of the fibers (3'C1 and 3'Cn + 1) having a half grammage, compared to the standard grammage of the multitude of other fibers, multitude of other fibers which make up the two so-called plies [St] (3C1, 3C2,3C3 to 3Cn ) and [S't] (3C'2, 3C'3 to 3C'n) that, moreover, the tablecloth [S't] comprises a fiber with a standard grammage of less than the tablecloth [St], so that '' once superimposed the elementary fibers that make up the two adjacent layers are staggered, which improves resistance to crack propagation

4. Method according to any one of claims 1 to 3 characterized in that the ribbon produced can include both an even number and an odd number of plies

5. Method according to any one of claims 1 and 4 characterized in that the thickness (ER) of the tape (14a) is adjusted by means (8) which regulates the outlet dimensions of the outlet calibration of the well (7 ), as a function of the dimensions of said strip (14d) measured by a sensor (11)

6. Method according to any one of claims 1 to 5 characterized in that a heating means (9) is placed at the outlet of the well (7)

7. Method according to any one of claims 1, to 5 characterized in that a cooling means (10) is placed at the outlet of the well (7)

8. Method according to any one of claims 1 to 5 characterized in that a heating means (9) is placed at the outlet of the well (7) and is followed by a cooling means (10)

9. Method according to any one of claims 1 to 8 characterized in that the thermosetting matrix can be based on epoxy, vinyl ester, polyester, ceramic slip

10. Method according to any one of claims 1 to 9 characterized in that the fiber used, or roving, may be carbon fiber, glass, aramid, basalt, ceramic fibers.