EP2467518B1 - Reinforcement strands of parallel glass fibers - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to coherent and flexible textile reinforcement used as a reinforcing product of composite articles, that is to say of resin-based articles (polyester or other) reinforced with reinforcing fibers.

Numerous coherent reinforcing textile reinforcing structures consisting of one or more layers of fibers bonded together are already known. The textile reinforcement is generally in the form of a flexible sheet packaged in a reel, which can thus be transported and handled at the place of use for the production of a composite article.

For the production of a composite article, the following procedure is generally carried out: a piece of appropriate surface of textile reinforcement is cut, it is placed in a mold, and a resin is penetrated which comes to drown the reinforcement in the mold. After polymerization, the resin and the reinforcement form a mechanically resistant structure.

The mechanical strength properties are obtained provided that the resin penetrates perfectly between the fibers forming the reinforcement, without leaving areas devoid of resin, and adhering perfectly to the fibers. It is also necessary that the fibers regularly occupy the volume of the composite article to be produced, in particular by following the shapes of the article when it is not flat.

Finally, it is necessary that the fibers themselves have a satisfactory mechanical strength to achieve an effective reinforcement.

Various reinforcing textile reinforcement structures have already been proposed.

Thus, the document EP 0 395 548 discloses the use of two layers of textile reinforcement, for example glass fibers, arranged on either side of a central layer consisting of a sheet of permanent-wave synthetic fibers, for example polyester fibers of 40 to 70 mm long that received a texturizing treatment. The textile reinforcement layers are bonded to the central layer by stitching / knitting.

The document EP 0 694 643 discloses the use of two layers of textile reinforcement disposed on either side of a central layer giving the thickness of said material, the layers being bonded together by sewing / knitting, and is provided against one of the outer faces a veil of synthetic fibers glued or sewn.

Sewing / knitting techniques are relatively slow, and the textile reinforcement thus produced have non-uniform deformation capabilities, and surface appearance defects.

In order to increase production rates and reduce defects resulting from knitting, it has recently been proposed in the documents FR 2 916 208 A1 and WO 2008/139423 A1 , to produce a fiber-based textile reinforcement comprising a thick and ventilated inner layer based on sections of synthetic fibers of 90 mm having received a treatment imparting a permanent crimp to them, and outer layers disposed on either side of the inner layer and comprising fiber sections with hot melt surface and reinforcing fibers of 50 mm. At least some of the thermofusible surface fiber segments penetrate along part of their length into the inner layer and partially adhere to each other and to the synthetic fibers of the inner layer.

An advantage of this structure is to give textile reinforcements great flexibility and great deformation capacity to follow the shapes of complex molds, the crimped synthetic fibers ensuring the maintenance of a sufficient volume of the inner layer for good penetration of the resin during subsequent molding.

The reinforcing fibers, such as sections of 50 mm glass fibers, present in the outer layers, make it possible to improve the mechanical characteristics of the composite article. But this improvement is small, because these reinforcing fibers are short and necessarily small, the proportion of glass fibers being limited by the presence of predominant synthetic fibers permanently crimped. For some applications, it remains desirable to significantly increase the mechanical characteristics of the composite article, including its resistance to rupture or bending.

According to a technique known for a long time and described in the document FR 1 394 271 A , and then more recently in the document EP 1 125 728 A1 parallel strands of glass fibers, derived from a coil or "roving", are arranged side by side in sheets and glued on a woven or non-woven fiber support which assembles them. Such wicks arranged side by side constitute a continuous band structure, with a weight of 500 to 1500 g / m ² .

The term "wire" refers to a set of single glass filaments, which generally have a diameter of 5 μm to 24 μm. A thread usually includes the order of 40 filaments. A set of threads is called a wick. A wick generally comprises about 50 wires.

The disadvantage of this known technique is the necessary presence of an adhesive to ensure the cohesion of the reinforcing product during its handling before injection molding. Indeed, the glue is likely to reduce the penetration capacity of the resin during molding, and to reduce the short or long term mechanical strength of the composite article from the molding.

Until now, in the coherent reinforcements based on unidirectional strands of glass fibers, the locks are assembled by stitching, which is a relatively slow process, and there is a need to increase substantially the speed of production of the textile reinforcements, to reach speeds of more than 10 m / min.

The invention goes against these difficulties and makes it possible to solve them.

SUMMARY OF THE INVENTION

The problem proposed by the present invention is to substantially increase the mechanical strength of the composite articles made from glass fiber molding reinforcements, while retaining the properties of consistency, flexibility and deformability of the molding reinforcements before molding, and retaining good properties of penetration and printing of the resin during molding.

Simultaneously, the invention aims to design a molding reinforcement that can be produced at high speed, reaching speeds of more than 10 m / min.

In addition, the invention proposes to improve if necessary the regularity of the surface of the composite articles made by molding the molding reinforcements.

Preferably, the invention also aims to allow the realization of reinforcing products continuous web, can be packaged in a coil, and can be cut or cut without risk of fraying or degradation of the edges.

• une première couche de fibres,
• au moins une couche de liaison en tronçons de fibres à surface thermofusible, liée à la première couche de fibres,
• certains au moins des tronçons de fibres à surface thermofusible pénétrant selon une partie de leur longueur dans la première couche de fibres et adhérant partiellement entre eux et aux fibres de la première couche de fibres,

et dans lequel la première couche de fibres comprend des mèches de fils de verre parallèles et disposées côte à côte en nappe, formant ainsi une couche de renfort.To achieve these and other objects, the invention provides a fiber-based web molding reinforcement comprising:

• a first layer of fibers,
• at least one bonding layer of fiber sections with a hot-melt surface, bonded to the first layer of fibers,
• at least some sections of thermofusible surface fibers penetrating along part of their length in the first layer of fibers and partially adhering to each other and to the fibers of the first layer of fibers,

and wherein the first fiber layer comprises strands of parallel glass strands disposed side-by-side in a sheet, thereby forming a reinforcing layer.

The thermofusible surface fibers of the bonding layer ensure the effective bonding of the strands of glass son without external glue, while maintaining flexibility and regularity of the molding reinforcement, and without deforming or breaking the glass son.

Simultaneously, such a molding reinforcement structure can be realized at a high speed, since interpenetration of the hot-melt surface fibers can be achieved by a light needling step, which is much faster than the sewing process.

Preferably, the sections of thermofusible surface fibers that penetrate the reinforcing layer are relatively spaced from each other, this spacing being equal to or greater than the needle pitch of a light needling: the surface density of such a light needling is about 5 to 10 needle penetrations per cm ² of backing layer. This results in a reduction of the bending stresses exerted on the glass fibers, and a corresponding reduction in the risks of rupture of the glass fibers.

The invention thus makes it possible to use the excellent mechanical properties of the unidirectional wicks of glass fibers, conferring excellent mechanical properties on composite articles made by molding such a reinforcement. The bonding layer, of which certain fiber sections penetrate and adhere to the fibers of the reinforcing layer, provides a sufficient temporary retention of the glass strands of the reinforcing layer after manufacture and before use of the molding reinforcement, conferring on the molding reinforcement a satisfactory coherence.

At the same time, the penetrating and adherent fiber bonding layer makes it possible to maintain the glass strands with only a small amount of material other than glass, that is to say by maximizing the relative amount of glass in the reinforcement. molding.

The bonding layer may be particularly thin, in the form of a web of fibers, for example with a basis weight of about 25 to 30 g / m ² .

The strands of glass strands may advantageously have a titer of between 2,400 and 4,800 tex approximately.

In such a wick the glass strands may advantageously be formed of an assembly of filaments having a unit diameter of between about 14 microns and about 17 microns.

Alternatively or in addition, the glass strands of the wicks may have a unitary title of 40 to 80 tex approximately.

According to a first embodiment, the reinforcing layer is bonded to a single heat-fusible surface fiber bonding layer.

According to a second embodiment, the reinforcing layer is bonded to two heat-fusible surface fiber bonding layers disposed on either side of the reinforcing layer.

According to a third embodiment, in a structure of one of the preceding embodiments, there is further provided an intermediate layer of glass son between the reinforcing layer and the bonding layer.

The intermediate layer may comprise a layer of glass threads of approximately 160 to 200 tex, parallel and oriented perpendicularly to the wicks, and / or a layer of glass fibers cut at approximately 50 mm, in bulk at all orientations, according to a weight of Approximately 50 to 80 g / m ² .

Advantageously, the molding reinforcement according to the invention may have a grammage of between 400 and 1800 g / m ² . This provides a good compromise between the thickness of the molding reinforcement and its deformation capacity before molding. For example, with five locks of 2400 tex per cm is produced a weight of 1200 g / m ² .

1. a) sur un support, déposer côte à côte une pluralité de mèches de fils de verre parallèles, pour former une nappe de mèches de fils de verre constituant une couche de renfort,
2. b) déposer, sur la couche de renfort, un voile de fibres chimiques à surface thermofusible, constituant une couche de liaison,
3. c) effectuer un aiguilletage léger pour faire pénétrer des tronçons de fibres à surface thermofusible de la couche de liaison dans la couche de renfort,
4. d) chauffer l'ensemble à une température suffisante pour ramollir et rendre collantes les fibres à surface thermofusible,
5. e) calandrer à froid l'ensemble.

According to another aspect, the invention proposes a method of manufacturing such a molding reinforcement, comprising the steps of:

1. a) on a support, depositing side by side a plurality of strands of parallel glass son, to form a sheet of strands of glass son constituting a reinforcing layer,
2. b) depositing, on the reinforcing layer, a web of chemical fibers with a hot-melt surface, constituting a tie layer,
3. c) lightly needling to penetrate sections of thermofusible surface fibers of the tie layer in the reinforcing layer,
4. d) heating the assembly to a temperature sufficient to soften and make sticky the hot-melt surface fibers,
5. e) cold calendering the whole.

In the case of a reinforcement with two bonding layers, in step a) a second web of chemical fibers with a hot-melt surface is placed on the support, constituting a second bonding layer, and then the strands of glass strands on the second bonding layer; in step c), a light double-sided switch is made.

In the case of an intermediate layer reinforcement, between step a) and step b), the pre-cut yarns or glass fibers of the intermediate layer are placed on the reinforcing layer.

Preferably, during the light needling step, needles are used whose driving barbs are placed in a diametral plane parallel to the direction of the son son of glass strands. In this way, it is avoided to break the glass son, and it is guaranteed to obtain a reinforcement providing a high mechanical strength to composite articles made from such a reinforcement.

SUMMARY DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue schématique en coupe longitudinale d'un renfort de moulage selon un premier mode de réalisation de l'invention ;
• la figure 2 est une vue schématique en perspective d'une mèche de fils de verre continus, en partie éclatée ;
• la figure 3 illustre en perspective un fil de verre continu ;
• la figure 4 est une vue schématique en coupe longitudinale du renfort de moulage de la figure 1, en cours d'aiguilletage léger ;
• la figure 5 est une vue schématique en perspective d'un renfort de moulage selon un mode de réalisation de l'invention ;
• la figure 6 illustre l'orientation des barbes d'entraînement des aiguilles lors de l'aiguilletage léger ;
• la figure 7 est une vue schématique en coupe longitudinale d'un renfort de moulage selon un autre mode de réalisation de l'invention ; et
• la figure 8 est une vue schématique en coupe longitudinale d'un renfort de moulage selon un autre mode de réalisation de l'invention.

Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, with reference to the accompanying figures, in which:

• the figure 1 is a schematic longitudinal sectional view of a molding reinforcement according to a first embodiment of the invention;
• the figure 2 is a schematic perspective view of a wick of continuous glass son, partly exploded;
• the figure 3 illustrates in perspective a continuous glass wire;
• the figure 4 is a schematic view in longitudinal section of the molding reinforcement of the figure 1 , during light needling;
• the figure 5 is a schematic perspective view of a molding reinforcement according to an embodiment of the invention;
• the figure 6 illustrates the orientation of the barbs driving the needles during light needling;
• the figure 7 is a schematic longitudinal sectional view of a molding reinforcement according to another embodiment of the invention; and
• the figure 8 is a schematic longitudinal sectional view of a molding reinforcement according to another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a first embodiment illustrated on the figures 1 and 5 , a molding reinforcement 1 according to the invention comprises two fiber layers, namely a reinforcing layer 2 and a bonding layer 3.

The reinforcing layer 2 comprises strands of glass threads, such as the strands 2a, 2b, 2c ( figure 5 ), which are parallel and arranged side by side in a single layer of wicks.

As an illustration, the figure 2 represents such a wick 2a or wire bundle such as son 20a, 20b, 20c, generally parallel to each other. In the wick 2a, the continuous wires 20a, 20b, 20c are normally in contact with each other. On the figure 2 , the wick 2a is illustrated partially exploded, the son 20a, 20b, 20c deviating from each other in the right part of the figure, for a better understanding of the wick structure. In a molding reinforcement, the wires 20a, 20b, 20c remain in contact with each other.

To obtain a good mechanical resistance to elongation, it will be advantageous to choose strands of continuous glass strands 20a ( figure 3 ), from a coil or "roving". The son are formed of an assembly of filaments such as filaments 200a, 200b, 200c whose unit diameter is between about 14 microns and about 17 microns. The unitary title of the glass strands 20a, 20b, 20c may for example be between 40 and 80 tex, by assembling about 50 glass filaments.

The wires 20a, 20b, 20c are actually formed of a sufficient number of filaments to prevent them from breaking during handling and use according to the invention, it being observed that the isolated filaments, in the size in which they usually come out of manufacturing, are too fragile for such manipulations and uses.

Alternatively, in order to obtain an elongation capacity of the molding reinforcement 1 before the molding step, strands of cut glass strands, having a length of about 10 cm to about 100 cm, are advantageously chosen, the strands being able to be offset longitudinally. relative to each other to overlap each other, and remaining each formed of an assembly of filaments. The length of such son is sufficient to ensure good mechanical properties to the composite article made by molding this molding reinforcement 1, and the elongation capacity improves the adaptation to a pre-existing object, for example to a tube for the covering of its outer or inner surface. This embodiment allows for example an application to the renovation of pipes in the basement.

The bonding layer 3 comprises fiber sections 3a with a hot-melt surface.

The fiber sections 3a with a hot-melt surface may be of any material having a sufficiently low melting temperature and good bonding properties with the glass strands 20a, 20b, 20c of the reinforcing layer 2.

Alternatively, the fiber sections 3a with a hot-melt surface may be two-component chemical fibers, comprising a central core in polyamide, polyester or polypropylene, and an outer sheath of copolyester, polyethylene or any other material having a lower melting temperature than that of the central core. Good results can be obtained by using a central core made of polyester and an outer sheath made of copolyester, or a central core of polypropylene and an outer sheath of polyethylene. Other pairs of materials can be used as coaxial two-component fibers: polypropylene and copolypropylene, polypropylene and ethyl vinyl acetate.

In that the central core of the two-component fiber has a higher melting temperature than the outer sheath, an accidental risk of complete melting of the first sections of hot-melt-surface fibers is avoided during the manufacture of the molding reinforcement. 1.

It is also effective to limit the risk, during a heating step for the manufacture of the molding reinforcement 1, that the hot-melt fiber sections are, by excessively high or poorly controlled heating, completely melted, forming uniform or impervious layers. to the resin by spreading their constituent material on the upper and lower faces of the reinforcing layer 2. The core of the bi-component fibers is not (or very little) impaired, and the properties of the tie layer 3 are thus preserved.

In addition, the use of bi-component hot-melt surface fibers outer sheath and central core reduces the polyolefin content of the molding reinforcement 1. This is advantageous, the resin being incompatible with the polyolefins.

Among the fiber sections 3a with a hot-melt surface of the connecting layer 3, at least some of these sections, for example the penetrating sections 3b on the figure 1 , penetrate along part of their length in the reinforcing layer 2 and partially adhere to each other and to the glass strands 20a, 20b, 20c of the reinforcing layer 2.

The penetrating sections 3b of fibers are regularly distributed along the surface of the molding reinforcement 1, for example at a surface density of 5 to 10 sections per cm ² of molding reinforcement, and ensure cohesion of the assembly, while retaining the deformability and flexibility properties of the molding reinforcement 1.

The molding reinforcement 1 according to the invention can be produced in the form of a continuous strip which is packaged in a long coil. In such a continuous band, the wicks 2a, 2b, 2c are formed of continuous glass strands 20a, 20b, 20c and are oriented in the direction of the strip length, or warp direction.

For example, a ply of strands of glass strands is deposited on a flat support to constitute the reinforcing layer 2, a layer of fibers with a hot-melt surface is deposited on the reinforcing layer 2 to constitute the bonding layer 3.

The assembly thus obtained is subjected to a light needling which penetrates at least 3b of the fiber sections 3a with hot-melt surface of the bonding layer in the reinforcing layer 2, the whole is heated to a temperature sufficient to soften the thermofusible portion of the penetrating sections 3b of thermofusible surface fibers and to ensure after cooling their bonding to the glass son 20a, 20b, 20c of the reinforcing layer 2.

The figure 4 schematically illustrates the light needling operation, in which one distinguishes needles 8 of pre-needling, which cause penetrating sections 3b of hot-melt surface fibers to penetrate the reinforcing layer 2.

The light needling carried out for example produces a surface density of perforations of about 5 to 10 perforations per cm ² . This must be compared to needling processes which typically achieve densities at least 10 times higher. The light needling allows a large flow during the manufacture of the molding reinforcement according to the invention.

As illustrated on the figure 6 during the light needling, the entrainment barbs such as the barbs 8a and 8b of the needles 8 are placed in a diametral plane containing the axis of the needle and parallel to the direction D of the son of the strands of threads. glass such as wick 2a. Due to the axial movement (arrow 8c) of the needle 8 during needling, the barbs 8a and 8b pass through the locks 2a by spacing the wires 20a, 20b, 20c ( figure 2 ) without breaking them.

The light needling performed is sufficient to ensure cohesion during the transfer of the molding reinforcement blank to a next work station, but it is insufficient to ensure the final cohesion of the molding reinforcement 1 and it is still not transportable at the exit of the needling machine for use as reinforcement.

The heating which is carried out after the light needling operation makes it possible to soften the hot-melt surface layer of the penetrating sections 3b of fibers of the tie layer 3 to make it adherent. The penetrating sections 3b of fibers which have been driven by the light needling needles 8 adhere to the glass strands 20a, 20b, 20c of the reinforcement layer 2. After cooling, the various layers 2, 3 of the molding reinforcement 1 are thus bonded together by the 3b needled and glued fibers. The molding reinforcement 1 is then transportable. The heating is set to soften and adhere the penetrating sections 3b of hot-melt surface fibers, but without melting them.

We now consider the figure 8 which schematically illustrates a second embodiment of the molding reinforcement according to the invention.

This second embodiment differs from the first embodiment of the figure 1 by the additional presence of a second bonding layer 4 on the other side of the reinforcing layer 2. Each bonding layer 3 or 4 is based on hot-melt surface fibers.

Penetrating sections 3b and 4b of thermofusible surface fibers are found which solidify the layers 2, 3 and 4.

We now consider the figure 7 , which schematically illustrates a third embodiment of the molding reinforcement according to the invention.

This third embodiment differs from the first embodiment of the figure 1 by the additional presence of an intermediate layer 5 of glass threads between the reinforcing layer 2 and the bonding layer 3.

According to a first possibility, the intermediate layer 5 comprises a layer 5a of glass threads of about 160 to 200 tex, parallel and oriented perpendicular to the wicks 2a, 2b and 2c, that is to say in the weft direction, and continuous along the entire width of the reinforcement.

According to a second possibility, the intermediate layer 5 comprises a layer 5b of glass fibers cut about 50 mm, in bulk at all orientations, with a weight of 50 to 80 g / m ² approximately.

According to a third possibility, illustrated on the figure 7 the intermediate layer 5 comprises a layer 5a of glass yarns in the weft direction and a layer 5b of glass fibers cut in bulk.

This third embodiment is suitable for applications requiring transverse reinforcement in the weft direction, and can improve the surface regularity of the composite article.

Penetrating sections 3b of thermofusible surface fibers are found which solidify the layers 2, 3 and 5.

Example

1. I) on a flat support, several strands of glass strands are deposited, laying them parallel in sheet and in a single thickness to form a reinforcing layer 2. The glass strands are formed of an assembly of 40 filaments having a unit diameter of about 15 μm, the threads having a title unitary of about 50 tex. The locks have a title of 2400 tex, and are present in quantity of five locks per cm.
2. II) on a conventional card, a web of chemical fibers with a hot-melt surface is produced. The sections of chemical fibers are made of two-component fibers, with a central core of polyester and a thermofusible outer sheath made of copolyester. The thermofusible copolyester outer sheath has a melting temperature of about 110 ° C.
   The two-component chemical fibers have a unit title of between about 2 deniers and about 4 deniers.
3. III) depositing the web of chemical fibers with a hot-melt surface on the reinforcing layer 2.
4. IV) the molding reinforcement blank thus produced is introduced by means of a conveyor belt into a needling machine. The density of the needles is 10 / cm ² . The penetration depth of the needles is 12 mm. The running speed of the carpet is 20 m / minute.
5. V) after the light needling operation, the molding reinforcement blank is introduced into a through air oven having a heating portion of 12 m length and a running speed of 20 m / min. The temperature of the through air oven is about 120 ° C.
6. VI) at the outlet of the through-air oven, a cold calendering is carried out which gives the molding reinforcement 1 its final thickness which is close to 4 to 5 mm.

The basis weight of the molding reinforcement 1 is between about 400 and 1,800 g / m ² .

The molding reinforcement 1 according to the invention can find advantageous applications in the manufacture of long composite parts, in particular wind turbine blades.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof within the scope of the claims below.

Claims (15)

1. Molding reinforcement (1) made of a fiber-based lap, comprising:

   - a first layer of fibers (2),

   - at least one coupling layer (3) made of portions of fibers (3a) with a hot melt surface, coupled to the first layer of fibers (2),

   - at least some (3b) of the portions (3a) of fibers with hot melt surface penetrating the first layer of fibers (2) over part of their length and adhering partially to one another and to the fibers of the first layer of fibers (2),

   characterized in that the first layer of fibers (2) comprises rovings (2a, 2b, 2c) of parallel glass strands (20a, 20b, 20c) arranged side by side in a lap, thus forming a reinforcing layer.
2. Molding reinforcement as claimed in claim 1, characterized in that the rovings (2a, 2b, 2c) of glass strands have a count of around 2 400 to 4 800 tex.
3. Molding reinforcement as claimed in one of claims 1 or 2, characterized in that the glass strands (20a, 20b, 20c) of the rovings (2a, 2b, 2c) are formed of an assembly of filaments of individual diameter ranging between around 14 µm and around 17 µm.
4. Molding reinforcement as claimed in any one of claims 1 to 3, characterized in that the glass strands (20a, 20b, 20c) of the rovings (2a, 2b, 2c) have an individual count of around 40 to 80 tex.
5. Molding reinforcement as claimed in any one of claims 1 to 4, characterized in that the penetrating portions of fibers are distributed with a surface density of 5 to 10 portions per cm² of molding reinforcement.
6. Molding reinforcement as claimed in any one of claims 1 to 5, characterized in that it comprises an intermediate layer (5) of glass strands between the reinforcing layer (2) and the coupling layer (3).
7. Molding reinforcement as claimed in claim 6, characterized in that the intermediate layer (5) comprises a layer (5a) of glass strands of around 160 to 200 tex, which are parallel and oriented perpendicular to the rovings (2a, 2b, 2c), and/or a layer (5b) of chopped glass fibers around 50 mm long applied in bulk in all orientations, at a grammage of around 50 to 80 g/m².
8. Molding reinforcement as claimed in any one of claims 1 to 7, characterized in that the reinforcing layer (2) is coupled to a single coupling layer (3) of fibers with hot melt surface.
9. Molding reinforcement as claimed in any one of claims 1 to 7, characterized in that the reinforcing layer (2) is coupled to two coupling layers (3, 4) made of fibers with hot melt surface, which are arranged one on each side of the reinforcing layer (2).
10. Molding reinforcement as claimed in any one of claims 1 to 9, characterized in that it has a grammage of between 400 and 1 800 g/m².
11. Molding reinforcement as claimed in any one of claims 1 to 10, characterized in that it is in the form of a continuous strip packaged in a reel, the rovings (2a, 2b, 2c) being formed of continuous glass strands (20a, 20b, 20c) and being oriented in the lengthwise direction of the strip.
12. Molding reinforcement as claimed in any one of claims 1 to 10, characterized in that it is in the form of a continuous strip packaged as a reel, the rovings (2a, 2b, 2c) being formed of chopped glass strands 10 to 100 cm long and oriented in the lengthwise direction of the strip.
13. Method of manufacturing a molding reinforcement as claimed in any one of claims 1 to 12, comprising the steps of:

    a) laying a plurality of parallel glass strand rovings (2a, 2b, 2c) side by side on a support to form a lap of glass strand rovings constituting a reinforcing layer (2),

    b) laying a web of chemical fibers with hot melt surface (3a) on the reinforcing layer (2) to constitute a coupling layer (3),

    c) performing a light needling operation to cause the portions (3b) of fibers with hot melt surface in the coupling layer (3) to penetrate the reinforcing layer (2),

    d) heating the whole assembly to a temperature high enough to soften the fibers (3a) with hot melt surface and make them sticky,

    e) cold rolling the assembly.
14. Method as claimed in claim 13, characterized in that, during the light needling step c), use is made of needles (8) the driving beards (8a, 8b) of which are positioned in a diametral plane parallel to the direction (D) of the strands of the glass strand rovings (2a, 2b, 2c).
15. Application of a molding reinforcement as claimed in any one of claims 1 to 12 to the manufacture of wind turbine blades or other long composite components.

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