WO2019087141A1

WO2019087141A1 - Composite product comprising a treillis and a polymer

Info

Publication number: WO2019087141A1
Application number: PCT/IB2018/058615
Authority: WO
Inventors: Christian Fischer; Julien Rion; Sophie DE RIJK
Original assignee: Bcomp Sa
Priority date: 2017-11-06
Filing date: 2018-11-02
Publication date: 2019-05-09
Also published as: FR3073167A1; FR3073167B1; CN210553147U

Abstract

The invention relates to a sheet-type or strip-type composite product, said product comprising a treillis (1) and a polymer, said treillis consisting of crisscrossed threads (3) defining mesh openings, said threads (3) consisting of fibres, each thread having an upper portion on the upper face of the treillis, a lower portion on the lower face of the treillis, and a median portion between the upper portion and the lower portion, the threads of said treillis being impregnated with said polymer, said impregnation being asymmetric such that the upper portion of the thread comprises a higher quantity of impregnated polymer than the lower part and the median part. The invention also relates to a method for producing said product, and to a device for producing said composite product.

Description

Composite product comprising a lattice and a polymer

Technical area

The present invention relates to a composite product, a method of manufacturing said composite product and a device for manufacturing such a product.

State of the art [0002] Composite products are conventionally used as reinforcing structure or framework, to improve the mechanical properties of a part.

[0003] A composite product frequently comprises a son assembly and a matrix made of a polymer. The assembly of wires can take different forms.

WO2015121583 discloses the manufacture of a composite in the form of an assembly of wicks impregnated and woven into strips. The strips typically have a width around 100 mm. In this method, the locks are impregnated on a fluidized bed. Then, the wicks are calibrated, in the sense that they are compressed in a heated calender that allows to give the desired dimensions to each wick.

[0005] WO2010034771 describes a polyamide composite article consisting of a fabric or assembly of threads, the threads being welded to one another by a polyamide resin. The impregnation of the son by the polyamide is under pressure by means of a hydraulic press. This type of impregnation requires a complex apparatus to install, for example presses with molds adapted to the shape and dimensions of the fabric.

The applicant wishes to manufacture composite products comprising an assembly of son impregnated with polymer and in the form of a grid, in other words a trellis. Such impregnated lattices may be used as such, or more frequently as semi-finished products to be coated with resin or polymer to serve as reinforcements in panels, or other flexible or rigid composite members. In a wire assembly in grid form, during the

Dusting of the polymer particles on the grid, the polymer particles can pass through the grid, via the opening of the mesh of the grid. For this reason, the grid usually rests on a belt of a conveyor, which moves the grid from dusting to heating. But this solution is not satisfactory: during the dusting the polymer particles are deposited on the son but also in the mesh opening of the grid. In this case, during heating,

the impregnation of the son is not satisfactory since the polymer melts and tends to accumulate between the grid and the strip. In addition, after heating, the mesh opening is clogged with polymer, it often happens that the grid remains stuck on the strip. The takeoff of the grid causes degradation of the impregnation of the grid.

Thus, the existing techniques do not allow to obtain a composite product based on a grid of son where the impregnation is satisfactory. Because of the poor impregnation of the son, the composite product obtained does not have the satisfactory mechanical properties. There is thus a need for a method of manufacturing a composite product comprising a wire assembly in the form of a grid.

Brief summary of the invention

An object of the present invention is to provide a method respectively a composite product free or which minimizes the

process limitations respectively known composite products.

Another object of the invention is to provide a composite product comprising a lattice son assembly. Another object of the invention is to provide a trellis composite product having improved mechanical properties, for example flexural strength and impact or impact resistance.

Another object of the present invention is to provide a composite product comprising a mesh of yarns based on plant fibers, including flax.

According to the invention, these objects are achieved in particular by means of a composite product sheet or strip, the product comprising a mesh and a polymer,

said lattice being formed of intertwined threads defining

mesh openings, the yarns being made of fibers,

said lattice comprising an upper face and a lower face opposite to the upper face,

each son having an upper portion on the upper face of the lattice, a lower portion on the lower face of the lattice, and a median portion between the upper portion and the lower portion,

the threads of the said lattice being impregnated with the said polymer, the said

impregnation being asymmetric so that the upper portion of the wire comprises a greater amount of impregnated polymer with respect to the lower portion and the middle portion.

It is interesting to be able to manufacture a composite product with a higher amount of polymer on the upper face, because it reinforces the bending stiffness when the composite is used as a reinforcing grid on a base material, for example a matte . Moreover, this makes it possible to reinforce the impact resistance during an impact or a load with an external element: the wire does not break cleanly but frays slowly, preserving a stabilizing net effect. [0015] Advantageously, the product according to the invention has improved mechanical properties while remaining light, since

the impregnation is asymmetrical which limits the mass of polymer. A symmetrical impregnation would significantly increase the weight of the composite product without significantly increasing the mechanical properties, including stiffness.

Thus, surprisingly, the product according to the invention is generally lighter than existing composite products having a comparable strength, but this improves the mechanical properties, including rigidity or resistance to the load or shock.

The composite products according to the present invention are in the form of plate or strip: they can be easily associated with another part, by gluing or welding, to strengthen said part. For example, in the automobile, a sheet or strip of composite product according to the present invention may be used as a reinforcement on a door trim or dashboard or other interior car trim part. The sheet or strip is laminated to a base material, such as, for example, a non-woven felt of plant fibers and polypropylene and this assembly is heated above the melting point of the polymer and shaped in a press mold.

(compression molding). The impregnation polymer deposited

asymmetrically, for example by the process according to the invention, penetrates deeper the wire during this compression molding step, thus ensuring a better quality of impregnation on the periphery of the wire, but the impregnation remaining asymmetrical.

The invention also relates to a method of manufacturing a composite product in sheet or strip, the method comprising the following steps:

Providing polymer particles and a lattice formed of intertwined yarns, the yarns being fiber-based, said lattice comprising an upper face and a lower face opposite to the face upper, the upper face being intended to receive the polymer particles;

- Sprinkle the upper face (6) of at least a portion of the mesh (1) of polymer particles using a mass of particles Ms so as to cover said upper face (6) with a mass

Md of polymer particles, the ratio between the mass of particles sprinkled Ms and the mass of deposited particles Md on the upper face being greater than 2;

- Heat the portion of the lattice covered with polymer particles by maintaining the upper face covered with respect to a heating element, the polymer particles being heated to a temperature at least equal to the melting temperature of the polymer, said heated portion of the lattice being kept flat and without contact on the upper face and on the lower face of said portion during heating.

The method according to the invention has the advantage over the prior art of allowing to provide a composite product in the form of mesh having satisfactory asymmetric impregnation of the son of the mesh. For this, the particles are sprinkled on the face

upper face of the mesh, then said face is placed opposite, that is to say opposite, a heating element. During heating, the heated portion is held flat against a heating element to allow a

homogeneous heating of the heated portion. Maintaining a flat portion prevents the molten polymer from moving on either side of the heated portion. Moreover, this also promotes uniform heating on the flat portion of the mesh. The heating from the upper face, on a portion maintained flat and without contact provides an asymmetrical impregnation.

During heating the heated portion is also maintained without contact on the upper face and the lower face. In other words, the heated portion is suspended, free from contact, no pressure is exerted on the heated portion during the impregnation of the polymer in the wire. For example, no element of the heating station comes into contact on the upper or lower side of the heated portion. For example, the heated grid portion is not on the band of a

conveyor. Thus, the molten polymer can be distributed without stress all around the son of the heated portion.

For example, if the heating is provided by an infrared oven comprising a chamber equipped with infrared lamps as a heating element: there is no contact between the upper face and the infrared lamps. There is also no contact between the underside and the lower edge of the chamber. This makes it possible not to disturb the

distribution of the molten polymer on the son of the heated portion.

Part of the molten polymer impregnates the upper face. Another part of the molten polymer flows by gravity around the periphery of the wire and gradually permeates the wire as the flow progresses. Thus, an asymmetric impregnation or impregnation gradient is observed from the upper face to the lower face: the heated portion of the mesh has a greater impregnation on the upper face than on the lower face. In other words, the section of the wire of the heated portion has an asymmetrical impregnation: on the lower part of the wire, there is less molten polymer available than on the opposite part, the impregnation is thus less deep. For example, the depth of impregnation is typically 40-80% of the radius of the wire in the upper part, 20-60% of the radius in the middle part and 10-40% in the lower part. In other words, the asymmetric impregnation is characterized in that between 40-90% (preferably 60-90%) of the impregnating polymer is in the upper part, 10-50% (preferably 10-30%) the impregnating polymer is in the middle part and 0-20% (preferably 0-10%) of the impregnating polymer is in the lower part.

Advantageously, according to the invention, the heating of the lattice portion covered with polymer particles is essentially carried out by the top, that is to say by the upper face. Thus, the molten polymer protects the fibers of the heating element, to prevent the son are degraded, for example burned, by the heating element. Advantageously, the polymer absorbs part of the heat, so that the fibers of the wire are less heated than the polymer, which allows to preserve them.

In one embodiment, the upper face of at least a portion of the mesh is covered with polymer particles, the polymer mass representing between 40% and 60% of the total mass of the impregnated mesh. In existing impregnation processes that use a web or a fabric, that is to say a continuous material without opening mesh, the amount of polymer particles sprinkled Ms corresponds to the amount of deposited polymer Md, and will be the amount of polymer in the composite. In other words, there is no loss because the particles do not pass through the sheet. The user chooses the amount sprinkled Ms according to the amount of polymer that he wants in the composite.

In contrast, in the present invention, the amount sprinkled Ms is not equal to the amount deposited Md, because a portion of the powdered polymer particles will be in the mesh and not on the son of the lattice, these particles will not participate. not to the impregnation of the wire.

[0027] Thus, if a web is replaced by a trellis and the conditions allowing a satisfactory impregnation of a web to a trellis are applied, the quantity of polymer that will impregnate the trellis will not be sufficient to provide a composite product with mechanical properties. satisfactory.

In the present invention, the Applicant has developed a method for depositing a quantity of Md particles on the son of the lattice to obtain a composite with satisfactory mechanical properties. This method notably comprises parameters of dusting optimized to ensure that a sufficient amount of particles on the wires despite the mesh openings. The amount of particles sprinkled with Ms is at least two times greater than the mass which it is desired to deposit on the lattice portion Md. In this case, the deposited mass Md is sufficient for the composite formed to have satisfactory mechanical properties.

In the present invention, a controlled deposition of particles of particles associated with a flat mesh transport and heating of the polymer without contact with the lattice makes it possible to keep enough polymer on the lattice and to have in the end a satisfactory impregnation.

The ratio Ms / Md is determined according to the lattice. Indeed, the mass of particles remaining on the son depends in particular on the diameter of the son, the opening of the mesh. The Ms / Md ratio can be predetermined by the raw mesh provider, the user can use this information to adapt the mass Ms according to the desired Md. Alternatively, the ratio can be determined at each use by the user.

Alternatively, in one embodiment, the method comprises:

Determine the Ms / Md ratio of the portion of mesh to be sprinkled so as to adjust the sprinkled mass Ms and cover the portion of the lattice with a mass of particles corresponding to Md;

In this case, the user can calculate this Ms / Md ratio for each raw lattice he wants to use.

The amount Ms must be chosen in accordance with the Ms / Md ratio of the mesh to ensure that there are enough polymer particles deposited on the wires so that the appropriate amount of polymer can impregnate into the son and result in a composite product with the desired mechanical properties. For example, if the quantity is too small, the flexural strength and resistance to impact or impact will not be sufficient.

Dusting is preferably carried out by a particle diffuser, for example a vibrating screen. In one embodiment, the Ms / Md ratio is between 2 and 9, preferably between 3 and 8, preferably 4 and 7. For example, for a mesh of 14 × 14 mm, with a weight of yarn Lin of 1500 tex, this ratio provides interesting results.

According to one embodiment, the Ms / Md ratio is between 5 and 15, preferably between 7 and 13, preferably 8 and 12. For example, for a mesh of mesh 28 × 28 mm, with a weight of yarn of lin of 3000 tex, an Ms / Md between 8 and 12 provides interesting results.

In one embodiment, the Ms / Md ratio is between 2 and 15. Ratios greater than 15 would be required for grids with larger meshes and larger wires, typically greater than 40 mm and 4000 tex, but Impregnation becomes too asymmetrical with powder only in the upper part of the wire, which no longer guarantees satisfactory mechanical properties.

In one embodiment, the deposited mass Md is between 43% and 233% by weight of the dry mesh, preferably between 67% and 150% by weight of the dry mesh.

The purpose of the dusting station is to deposit polymer particles on the lattice. There are several devices for carrying out this action: for example the dusting station comprises a drum with a system of combs on the periphery, the powder on the drum is then deposited (falls) on a vibrating screen. Alternatively, one could use a dispenser with a distribution control means for depositing particles.

only on the wire in a specific quantity.

In one embodiment, the grid is disposed on a support during the dusting, for example a conveyor belt. At the end of the dusting, at least a portion of the dusted grid leaves the support, before heating, so as to cause the particles accumulated in the mesh openings to fall by gravity and to recycle them for the dusting of another section. trellis. According to one embodiment, the method comprises:

- Cooling said heated portion of the lattice, said portion being

kept flat and without contact on the upper face and on the lower face of said portion during cooling, the cooling step taking place after the heating step. The cooling allows the molten polymer which has impregnated the wire or which is on the surface of the wire, to go from the molten state to the solid state.

Advantageously, during cooling, in a manner similar to heating, the portion comprising molten polymer is kept flat and without contact. In other words, there is no pressure or stress or contact on the impregnated wire and covered with molten polymer, and the mesh is kept flat. In this case, the distribution of the molten polymer is subjected only to gravity, no external stress disturbs the distribution of the polymer. For example, when the mesh rests on a support or when it is inclined, and the molten polymer solidifies, the asymmetric impregnation of the lattice can be modified by the inclination of the lattice, or by the support under the lattice. Furthermore, if the mesh is on a support during cooling, the mesh can remain stuck on the support. Finally, any contact with a support can modify the circular geometry of the impregnated threads which is advantageous for the reinforcement effect of the trellis. Thus, keeping the lattice flat and non-contact during cooling avoids these disadvantages and maintains the asymmetric distribution of the polymer on the lattice during the

cooling and not to alter the circular geometry of the wires.

According to one embodiment, the method comprises:

Laminate the underside and / or the upper face of the heated portion on a mat.

The mat can be laminated on the underside or alternatively on the upper face of the portion of the heated mesh. Preferably, the mat is rolled on the underside of the heated portion. The Applicant has observed that when the mat is adhered to the lower part of the impregnated thread, the opposite of the upper part which comprises more polymer, the mechanical properties are better. It is also possible to make a "sandwich" stack, the heated portion being between two mats. The rolling of the lattice on a mat makes it possible to increase

significantly stiffness of the mat with reduced weight. Preferably, the rolling step takes place between the heating step and the cooling step. In this case, at least a portion of the polymer is still melted, which promotes adhesion between the mat and the mesh. The mat is contacted with the molten polymer.

Advantageously, the contacting is done with a very low pressure or without pressure on the trellis, to minimize the impact of rolling on the thickness (the section) of the trellis, because the lattice son acting as reinforcing ribs, their effect is directly related to the final thickness of the lattice.

For example, the mat is laminated on the underside of the lattice. For example, the means for rolling comprises a scroll roll, a contact roll and a pressure roll. The unwinding roll unrolls the mat towards a contact roll which has the mat facing the underside of the lattice. The pressure roller and the contact roller are on either side of the mesh, respectively with respect to the lower face and the upper face. Preferably, the spacing between the contact roller and the underside of the mesh corresponds to the thickness of the mat or slightly greater, so that the contact roller does not exert pressure or a minimum pressure on the underside of the lattice. Preferably, the spacing between the pressure roller and the contact roller corresponds to the thickness of the mesh at the outlet of the heating, plus the thickness of the mat in case of mat. This minimizes the pressure on the lattice and the deformation thereof. Preferably, the pressure roll is covered with a non-adhesive material, for example a silicone component or Teflon, not to adhere to the upper or lower face of the impregnated mesh. The contact surface is also preferably soft and elastic, in order to adapt to the geometry of the mesh and to minimize crushing of the wires. Alternatively, it is possible to roll the mat on the lattice after cooling. In this case, it is possible to glue the mat to the lattice using an adhesive. Another possibility is to heat the mesh to melt at least a portion of the mesh and adhere the mat. Another possibility is also to heat a prepreg to melt the thermoplastic matrix which will then adhere to the lattice. Alternatively, it is possible to heat both the mesh and the mat to melt the matrix of both components and adhere.

In one embodiment, the upper face of at least a portion of the mesh is covered with at least the same surface mass of polymer particles as the density of the non-impregnated mesh. For example, a mesh of 200 g / m ² will be sprinkled with at least 200 g / m ² of polymer particles. The Applicant has observed that this allows good impregnation results.

According to one embodiment, the method comprises: - Preheat at least a portion of the mesh before sprinkling.

Preheating makes it possible to dry the mesh when the yarns are wet or contain moisture, as is frequently the case with vegetable fibers. In addition, it improves the adhesion of solid polymer particles which adheres more easily on a preheated wire.

According to one embodiment, the method comprises:

- Cut the mesh into a sheet or strip after the heating or cooling step. According to one embodiment, the method comprises:

Compress the impregnated mesh with molten polymer at the outlet of the heating with a calendering device to favor

the impregnation of the polymer in the yarn.

calendering comprising at least one soft roll in contact with the upper surface of the mesh, the hardness of the flexible roll being between 10 and 50 Shore A;

In one embodiment, the particles have a dimension of between 100 μηη and 600 μηη.

According to one embodiment, the mesh has a polygonal mesh, for example rectangular or square. Alternatively, the mesh may have a mesh comprising curved edges.

In one embodiment, the mesh comprises a mesh with a mesh opening greater than or equal to 1 cm, preferably between 1 cm and 6 cm, preferably between 1 cm and 3 cm.

According to one embodiment, the son are based on plant fiber, for example linen or from cellulosic fibers. In one embodiment, the fiber is selected from flax, hemp, kenaf, nettle, jute, abaca, sisal, bamboo. The vegetable fiber-based yarns generally have some twisting introduced during spinning, which improves the radial compressive strength of the yarn, which will thus have a greater thickness after rolling on a mat and will therefore improve the lamination. bending reinforcement effect of the lattice. The density of the plant fibers is also low, of the order of 1.2-1.6, which makes it possible to obtain a greater thickness of mesh for a given weight, and thus to further improve the reinforcing effect of the lattice. Due to their natural origin, the use of these fibers also reduces the ecological impact of the production of parts reinforced by the lattice.

In one embodiment, the plant fiber-based yarns are composed of at least 50% by weight of short fibers from scutching tows or combing. These short fibers have the advantage of being less expensive than the long fibers extracted for example during the scutching of flax. The use of short fibers does not compromise the

mechanical performance of the yarn once impregnated with polymer.

According to one embodiment, the son are based on synthetic fiber, for example based on polymer, carbon fiber, fiberglass, basalt fiber or a mixture of these different types of fibers. .

According to another embodiment, the yarn is based on animal fiber, for example silk or wool.

According to another embodiment, the son are based on plant fiber and at least one non-plant fiber, for example a synthetic fiber. In this embodiment, the yarn is based on at least two different fibers.

According to one embodiment, the threads of the intersecting lattice are held together by a very fine thread, for example polyester, applied by sewing, knitting or weaving. This mode of assembly of the trellis has several advantages. It allows the composite product obtained to remain well bonded and homogeneous, even when the impregnating polymer is in the molten state, which is advantageous when molding composite parts by compression molding of the composite product described herein. Furthermore, this assembly by a polyester thread allows still slight slippage between the son, which allows a large formability in 3 dimensions during the molding of composite parts by compression molding.

In one embodiment, the heating element is an infrared oven or a convection oven.

According to one embodiment, the polymer has a melt index greater than or equal to 30 (according to standardized test, g / 10 min to 2.16 kg).

In one embodiment, the polymer is chosen from polypropylene, polyethylene, polyamide or co-polyamide, polyester or co-polyester, thermoplastic polyurethane, co-polyoxymethylene, thermoplastic cellulose esters (Cellulose acetate propionate), polylactic acid (PLA) or derivatives thereof or mixtures thereof.

In one embodiment, the polymer is chosen from thermoplastic polymers, for example polypropylene,

polyethylene, polyamide or co-polyamide, polyester or co-polyester, thermoplastic polyurethane, co-polyoxymethylene, thermoplastic cellulose esters (Cellulose acetate propionate), acid

polylactic (PLA). The composite product serves as reinforcement or framework to ensure the rigidity of the material, including flexural stiffness. The product also improves impact or impact resistance.

The invention further relates to a device for manufacturing a composite product comprising: - A sprinkling station comprising means for sprinkling polymer particles on a mesh formed of intertwined son, the son being based on fibers, said lattice

comprising an upper face and a lower face opposite to the upper face, said sprinkling means for sprinkling the upper face of at least a portion of the mesh with the polymer particles to cover said upper face of polymer particles;

- A heating station positioned downstream from the

dusting, said heating station comprising a heating element for heating a portion of the lattice covered with the polymer particles, the polymer particles being heated to a temperature at least equal to the melting temperature of the polymer; characterized in that the device comprises displacement means arranged to maintain said heated portion of the mesh flat and without contact on the upper face and on the underside of said portion during heating.

The displacement means are arranged to move said portion of the lattice successively from the sprinkling station to the heating station (and then to the cooling station if the device comprises a cooling station). In addition, the displacement means are arranged to maintain said heated portion of the mesh flat and without contact on the upper face and on the underside of said portion being heated. In other words, when the portion moves with respect to the heating element, or is fixed under the heating element, the displacement means keep it flat and without contact on the lower and upper faces of the heated portion. The means of

displacement keep the lattice by contact outside the heated portion. The mesh works in traction, it is tensioned between the displacement means that keep the lattice flat during heating, and optionally cooling and dusting. The displacement means maintain and tend the mesh by contact with the mesh, but outside the portion of the mesh which is at the level of the heating station, and optionally at the cooling station. In other words, it is important to avoid contact on the useful portion of the lattice, the one that is heated, during heating and optionally cooling. For example, the displacement means comprise a unwinder, a winder, and a traction unit, these three elements being positioned outside the portion of the heated mesh, and optionally outside the portion of the lattice cooled.

The unroll unrolls raw mesh, that is to say without polymer, in the direction of the winder. The unwinder exerts a pulling force on the lattice so that the lattice is under tension.

The winder winds the cooled composite product, for example by a cooling unit or in the open air, downstream of the heating.

The unwinder and the traction unit cooperate to control the tension of the lattice (and then the composite product) and the unwinding speed. The traction unit comprises for example two rollers on either side of the composite product: an upper roll and a lower roll positioned respectively with respect to the upper face and the lower face of the mesh. The upper and lower rollers rotate in opposite directions, one clockwise, the other in the opposite direction, to advance the mesh (and then the product) from the unwinder to the reel. Alternatively, the traction unit may comprise two face-to-face strips, or a strip facing a cylinder.

The speed of displacement is for example between 0.5 m / min and 5 m / min, preferably between 1.0 and 2.0 m / min, for example 1.5 m / min. The speed of movement depends on the heating power available: the higher the speed, the greater the heating power must to be important to guarantee the fusion of the polymer. In particular, the applicant has obtained good results with an infrared heater with a power of 1 15kW, over the width of the mesh, for example 1400mm, and a speed of 1.5 m / min. According to one embodiment, the speed of movement of the mesh is constant during the dusting, preferably during dusting and heating. It is advantageous to perform a constant speed sprinkling to improve the homogeneity of the dusted and deposited particle mass. When heating and also carried out at constant speed, each portion of covered trellis that runs through the heating station is exposed to the same amount of heat. A speed

constant participates in obtaining a satisfactory impregnation of the lattice and thus a composite with satisfactory mechanical properties. Indeed, a jolt or a change of speed can cause a drop of the powder deposited on the son, thus changing the Ms / Md ratio, the mass Md thus being insufficient locally to ensure good

impregnation of the lattice.

The space between the upper roll and the lower roll is chosen to control the pressure exerted on the composite product. The pressure must be sufficient to drive the composite product. The pressure must be limited so as not to degrade the composite product. For example, the spacing is between 0.8 and 1.5 mm.

In one embodiment, the device comprises a cooling station downstream of the heating station to cool said portion, said displacement means for maintaining said heated portion of the mesh flat and without contact on the upper face and on the underside of said portion during cooling.

The cooling station is used to cool the polymer to allow the solidification of the polymer. For example, the position of

cooling comprises at least one fan that is beating gas, for example air or an inert gas, to cool the polymer. Alternatively, compressed air can be directed on the mesh to force its cooling.

In one embodiment, the heated portion is maintained without contact and flat during heating, cooling, and between heating and cooling. Thus, no contact comes to alter the geometry of the son impregnated from heating to cooling.

In one embodiment, the device comprises a rolling station for rolling the impregnated mesh on a mat, in particular the lower face and / or the upper face of the heated portion on a mat. [0081] Preferably, the rolling station is downstream of the heating station.

In one embodiment, the device comprises a preheating station, upstream of the dusting station, said station comprising a preheating element for preheating at least the portion of the mesh to be covered with particles.

According to one embodiment, the device comprises a recycling station downstream of the sprinkling station. The recycling station is used to recover the polymer particles deposited in the opening mesh mesh during the dusting, these particles can be reused. The recycling station is downstream of the dusting station.

According to one embodiment, the device comprises a belt conveyor for holding the grid during the dusting. The conveyor belt which holds the mesh is upstream of the heating, it supports the tension of the mesh, which determines the height of the mesh under the heating and promotes the flat position of the mesh at the entrance of the heating station and during heating .

For example, when the device comprises a belt conveyor for moving the trellis during the dusting, the post of recycling comprises a reservoir in which the particles of the mesh opening of the grid deposited on the belt of the conveyor are poured.

In one embodiment, the device comprises a cutting station downstream of the heating station, preferably downstream of the cooling station. The cutting station makes it possible to cut the composite product into a strip or sheet of determined size depending on the use of the composite product.

According to one embodiment, the device comprises a calendering device. For example, the calendering device comprising two opposed rollers and arranged on either side of the mesh, the roller facing the upper face being in flexible matter. The term flexible here means a hardness of the roll between 10 and 50 Shore A. The other roll may be flexible or have a hardness greater than that of the flexible roll, and is for example steel.

The calendering device performs a moderate pressure on the upper face which promotes the impregnation of the polymer. The flexible surface of the roll keeps the circular geometry of the wire.

According to the present invention, the composite product is in sheet or strip. A sheet or a strip designates a planar object, defined in a plane (x, y), and in which the thickness along the z axis is much smaller than the dimensions along the x and y axes. A strip is a sheet in which in one (x, y) plane, one of the dimensions is much larger than the other.

In the present invention, the term trellis is synonymous with grid and refers to an assembly of son that intersect to define meshes. To form the meshes, the son are secured together, for example glued or welded, or held by support son.

In the present invention, a yarn is formed of fibers. [0093] Advantageously, the impregnated mesh is more easily manipulated. The fibers of the yarns are at least partially embedded in the polymer. The wires are integral with each other, the assembly does not break during handling. The invention also relates to the use of a lattice impregnated with polymer to manufacture a composite product comprising said lattice and a support, said polymer for securing the lattice on said support. The use of a mesh prepreg with a coating of molten polymer makes it possible to facilitate the adhesion and the fixing of the mesh on the support. The support may be a mat or any other planar support to be reinforced.

The invention also relates to a composite product comprising on the one hand a mesh pre-impregnated with a polymer, and on the other hand a mat pre-impregnated with a polymer identical to or different from the polymer of said lattice. The mat and lattice are prepregs, which facilitates the adhesion of the lattice to the mat.

In the present invention, the term "mat" designates a support or a plate, in other words a sheet or felt, composed of randomly organized fibers. A mat is a nonwoven material. The present invention preferably relates to rolling on mat, but the invention is not limited to this type of support. It is possible to use supports composed of unidirectional, multidirectional, woven or non-woven fibers.

According to the present invention, the term "composite product" or "composite" is a product that comprises at least two different and somewhat homogeneous materials that are associated. The association confers on the set of properties that none of the components taken separately possesses. In the present invention, the composite product may be a wire mesh and a polymer, the wires being impregnated at least

partially of polymer. Said wire mesh prepreg can be embedded in a polymer identical to or different from the polymer of said wire. The product composite may also be a mesh of pre-impregnated son, said lattice being laminated on a mat, said mat may also be prepreg of a polymer identical to or different from the polymer of said yarn. In this case, the use of a prepreg mesh laminated on a prepreg or non-adhered mat facilitates adhesion of said mesh. The composite product is then a laminated composite.

The embodiments described for the method according to the invention apply mutatis mutandis to the device, to the composite product and to the use of a composite product according to the invention, and vice versa.

BRIEF DESCRIPTION OF THE FIGURES [0099] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

Figure 1 shows a general view of a raw lattice, without polymer, usable in the invention;

[00101] Figure 2 shows a block diagram of the invention according to a first embodiment;

[00102] Figure 3 shows a general view of a composite product obtained according to the first embodiment;

[00103] Figure 4 shows a section of a wire of the composite product according to the first embodiment; [00104] FIG. 5 is a block diagram of the invention according to a second embodiment;

[00105] Figure 6 shows a general view of a composite product according to the second embodiment of the invention. Example (s) of embodiment of the invention

Two embodiments of the present invention are shown in Figures 1 to 6, but the invention is not limited to the embodiments shown in Figures 1 to 5.

[00107] Figure 1 shows a mesh 1 used in the invention to manufacture a composite product 2. The mesh 1 shown in Figure 1 is the lattice before dusting and impregnation, in other words a raw lattice, that is to say say without polymer. The mesh 1 comprises interwoven son 3. The son 3 are glued or sewn together at each intersection 4. The mesh 1 has a rectangular polygonal mesh size 14x14mm or 28x28mm. But it is also possible to use mesh of 10 to 60 mm mesh, for example polygonal.

[00108] The mesh 1 comprises an upper face 6 and a face

lower 7.

[00109] The son 3 are based on flax fiber. In this embodiment, the yarns are exclusively based on linen, but it is possible to use yarns made of a different material, or yarns with bases of several different types of fibers, for example hemp, kenaf, nettle, jute, abaca, sisal, cotton, polymeric fibers, carbon fiber, glass, basalt, aramid. FIG. 2 shows a device according to a first embodiment for manufacturing a composite product 2 shown in FIG. 3. In this embodiment, the composite product 2 is a prepreg 10 which comprises a mesh 1 impregnated with a polymer 1 1.

[001 1 1] The device of this first embodiment shown in Figure 2 is a production line 12 which comprises a sprinkling station 13, a recycling station 14, a heating station 15, a cooling station 16. [001 12] To ensure the movement of the mesh 1 from the heating station 13 to the cooling station 16, the chain 12 comprises a unwinder 17, a traction unit 18 and a winder 19. The unwinder 17 unrolls the mesh 1 of raw yarn 3, without polymer, to the sprinkling station 13. The traction unit 19 is positioned after the cooling station 14 and pulls the trellis 1 in front of each station of the chain 12. The traction unit 18 comprises a upper roller 20 vis-à-vis the upper face 6 and a lower roller 21 vis-à-vis the lower face 7. The mesh 1 is held between the upper roller 20 and lower 21 which allows to pull said mesh 1 The winder 19 winds the prepreg 8 at the end of the chain 12. In this embodiment, the trellis travels at a speed of 1.5 m. min ^"1 .

[001 13] The chain 12 makes it possible to successively pass a portion of trellis by the sprinkling stations 13, recycling 14, heating 15 and cooling 16. Before the sprinkling station 13, the trellis portion 1 is with a wire 3 to the raw state; after the cooling station 16, said portion of raw mesh has been transformed into a prepreg portion 10.

[001 14] At the beginning of the chain 12, at the exit of the unwinder 17, the mesh 1 rests on the band of a belt conveyor 22 which maintains the mesh 1 with respect to the sprinkling station 13 and guides the trellis 1 to the recycling station 14. In this chain 12, the dusting station 13 is a vibrating screen 28 which sprinkles polymer particles over the entire surface of a portion of the mesh 1, in other words on the wires 3 and in the openings of the meshes 5 of the lattice. For example, for a lattice of 14x14 mm, the sieve powder 1200 to 1300 g. m ² of polymer particles (mass dusted Ms) so that after the recycling station, there remains 200 to 240 g. m ² of polymer particles on the son 3 (mass deposited Md), the ratio Ms / Md is thus between 5 and 6. In this embodiment, the polymer 1 1 is polypropylene. For a lattice of 28x28 mm, the sieve sprinkles 1900-2050g. m- ² (Ms) to obtain 200-240g.m- ² (Md). The belt of the conveyor 22 collects the polymer particles that are in the mesh 5, to transfer them to the recycling unit 14.

[001 16] The sprinkled mesh portion then passes through the heating station 15. The heating station 15 is here an infrared oven 23. The infrared oven 23 heats the portion sprinkled with polypropylene (PP) from above, that is to say from the upper face 6, to a

temperature of 200 to 220 ° C. The PP melts and protects the flax fiber of the 3 wire from infrared radiation, so that the flax stays below 185-190 ° C and does not burn.

[001 17] At the outlet of the heating, the heated portion passes through the cooling station 16. In this embodiment, the station of

cooling 16 comprises air fans (not shown in the figures) positioned opposite the upper face 6. [001 18] During heating and cooling, the heated portion is tensioned and without contact, thanks to the voltage conferred by the traction unit 18.

[001 19] At the output of the traction unit 18, the prepreg 10 is wound on the winder 19. [00120] Figure 4 shows a section of impregnated wire 24 which illustrates the asymmetrical impregnation of the wire 24. L impregnation allows

converting the raw yarn 3 into impregnated yarn 24. The yarn 24 of the prepreg 10 comprises an upper portion 25, a central portion 27, and a lower portion 26. The upper portion 25 is the portion exposed on the upper face 6 of the lattice; the lower part 26 is the part exposed on the lower face 7 of the mesh 1.

The upper part 25 is impregnated more deeply than the lower part 26. In fact, the polymer 9 is deposited on the face

upper 6, and bottom from the upper face 6. Part of the polymer The polymer 1 1 does not impregnate the upper part 25 of the wire 24 flows around the periphery of the wire 24 by gravity, and becomes impregnated as and when. Thus, an asymmetric distribution of the polymer is obtained: on the lower part of the wire 27, there is less molten polymer available than on the opposite part,

the impregnation is thus less deep. The depth of impregnation is typically 40-80% of the radius of the wire in the upper part, 20-60% of the radius in the middle part and 10-40% in the lower part. In other words, the asymmetric impregnation is characterized in that between 40-90% of the impregnating polymer is in the upper part, 10-50% in the middle part and 0-20% in the lower part.

The central portion 27 of the wire 22 is little or not impregnated, the bulk of the polymer being distributed between the upper 25 and lower 26 and the flanks of the middle portion.

The molten polymer essentially fills voids between the fibers making up the raw wire 3, so that the impregnated wire 24 is generally about 5-20% larger in diameter than the raw wire 3. FIG. according to a second embodiment for manufacturing a composite product 2 shown in Figure 6. In this embodiment, the composite product 2 is a rolled product 100 which comprises a prepreg 10 laminated on a support, here a mat 101.

The device of this second embodiment shown in Figure 5 is a production line 102 which comprises a dusting station 103, a recycling station 104, a heating station 105, a cooling station 106. These positions are the same as those of the first embodiment of the chain 12.

As in the chain 12 according to the first embodiment, the chain according to the second embodiment comprises a unwinder 107 and a traction unit 108, and a belt conveyor, these elements. functioning as in the chain 12 according to the first mode of

production.

The chain 102 according to the second embodiment allows to manufacture laminated composite 100. For this, the chain 102 comprises a rolling station 130 located between the heating station 105 and the cooling station 106. The rolling station 130 comprises a scroll roll 131, a contact roll 132 and a pressure roll 133. The mat 101 is wound on the roll roll 131. The contact rolls 132 and the pressure roll 133 are positioned respectively opposite the face lower 7 and the upper face 6.

The scroll roll 131 unrolls the mat 101 to the contact roller 132. The contact roller 132 guides the mat towards the lower face 6 of the mesh. The lower face 7 comprises at least a portion of polymer 1 1 in the molten state, capable of having an adhesive function. The mat and the prepreg are sandwiched between the contact roll 132 and the pressure roll 133. The spacing between the contact roll 132 and the pressure roll 133 corresponds to a distance slightly less than the sum of the thicknesses of the mat added to that of the impregnated yarn 22, typically 5-20% lower, so that the mat 101 and the prepreg 10 are pressed slightly one on the other. The distance preferably depends on the type of mat. This improves the adhesion of the prepreg 10 to the mat 101, minimizing the maximum

changing the thickness of the impregnated yarn 24.

In one embodiment not shown, the rolling is performed on the upper face 6. In another embodiment not shown, the rolling is performed on the upper face 6 and the lower face 7.

Downstream from the rolling station 130, the cooling station 105 cools the laminated composite 100 at the exit of the rolling station 130. The chain 102 further comprises a cutting station downstream of the cooling station 10. The cutting station 134 makes it possible to cut the laminated composite 100 into a sheet 135 of predetermined size.

A sheet 135 of laminated composite obtained by the chain 102 is shown in Figure 6. The sheet 135 comprises a prepreg 10 and a mat 101.

Two examples of composite products manufactured by the process according to the invention are described below.

In these two examples, the mesh comprises flax yarns. The powdered polymer is a polypropylene powder comprising particles of 100 to 400 μηη. The device used includes a vibrating screen dusting station with a belt conveyor supporting the mesh during dusting.

For heating, an infrared heating oven is used exclusively on the upper face of the sprinkled mesh. During the

manufacturing, the lattice is maintained by a traction unit on the one hand and a winding unit. The mesh is unwound at a speed of 1.5 m / min continuously, in other words at constant speed (smoothly).

For each example, the requestor determined several Ms, each Ms corresponding to a Md, which makes it possible to determine the Ms / Md. In other words, the Applicant has determined that it should be the mass of particles sprinkled Ms to obtain the desired deposited mass on the mesh.

In this example 1, the product is a lattice having a mesh of 14 × 14 mm, the linen yarn used having a weight of 1500 tex. [00137] For Ms between 400 g / m2 and 1360 g / m2, the Ms / Md ratios vary between 4.5 and 6.3, for example:

- Ms = 400 g / m2; Md = 88 g / m2; Ms / Md = 4.5

MS = 1230 g / m2; Md = 200 g / m2; Ms / Md = 6.1 - Ms = 1360 g / m 2; Md = 269 g / m 2; Ms / Md = 5.1

[00140] Example 2:

In this example 2, the product is a lattice having a mesh of 28 x 28 mm, the linen yarn used having a weight of 3000 tex.

For Ms between 400 g / m2 and 2056 g / m2, the Ms / Md ratios vary between 10.1 and 12, for example:

- Ms = 400 g / m2; Md = 45 g / m2; Ms / Md = 8.8

MS = 1555 g / m 2; Md = 139 g / m2; Ms / Md = 1 1.2

- Ms = 2056 g / m2; Md = 238 g / m 2; Ms / Md = 8.7

Reference numbers used in the trellis figures

Composite product

Raw wire

Intersection

stitch

Upper side

Lower face Prepreg

polymer

Production line

Sprinkling station

Recycling station

Heating station

Cooling station

Dispenser

Traction unit

reel

Upper roll

Lower roll

Belt Conveyor

Infrared oven

Impregnated thread

Upper part of the impregnated yarn

Lower part of the impregnated yarn

Central part of the impregnated yarn

Composite laminated vibrating screen

Mast

Production line

Sprinkling station

Recycling station Heating station

Cooling station Unwinder

Traction unit Upper roll

Lower roll

Belt conveyor Rolling station

Rolling roll

Contact roll

Pressure roll

Cutting station

Laminated composite sheet

Claims

claims

A composite product (2, 10, 100) in sheet or strip, the product comprising a mesh (1) and a polymer,

said lattice being formed of interwoven yarns (3) defining mesh openings (5), the yarns (3) being based on fibers,

said lattice (1) comprising an upper face (6) and a lower face (7) opposite to the upper face (6),

each yarn (3) having an upper part (25) on the upper face (6) of the lattice (1), a lower part (26) on the lower face (7) of the lattice (1), and a middle part ( 26) between the upper part (26) and the lower part (26),

the wires (3) of said mesh (1) being impregnated with said polymer, said impregnation being asymmetrical so that the upper part (25) of the wire comprises a greater quantity of polymer impregnated with respect to the lower part (26) and the middle part (27).

2. The composite product (2, 10, 100) according to claim 1, wherein the asymmetric impregnation being characterized by a depth of impregnation of the polymer on the wire radius between 40% and 80% of the radius of the wire in the part. upper (25), between 20% and 60% of the radius in the middle part (26), between 10% and 40% of the radius in the lower part (26).

3. A composite product (2, 10, 100) according to claim 1, wherein the asymmetric impregnation being characterized in that between 40-90%, preferably 60-90%, of the impregnating polymer is in the upper part, 10-50%, preferably 10-30% in the middle part and 0-20%, preferably 0-10% in the lower part.

4. composite product (2, 10, 100) according to one of claims 1 to 3, wherein the fibers are selected from vegetable fibers, including flax, hemp, jute, cotton, kenaf, nettle, abaca, sisal, bamboo, preferably flax. 5. Composite product (2, 10, 100) according to one of claims 1 to 3, wherein the fibers are selected from synthetic polymer fibers, carbon fibers, glass fibers, or a mixture of these fibers.

6. composite product (2, 10, 100) according to one of claims 1 to 3, wherein the fibers are selected from animal fibers, for example silk or wool.

7. composite product (2, 10, 100) according to one of claims 1 to 3, wherein the fibers are selected from vegetable fibers, including flax, hemp, jute, cotton, kenaf, nettle, abaca, sisal, bamboo, preferably flax, of which at least 50% by weight are short fibers from scutching tows or combing tows.

8. composite product (2, 10, 100) according to one of claims 1 to 7, wherein the polymer is selected from polypropylene, polyethylene, polyamide or co-polyamide, polyester or co-polyester, the

thermoplastic polyurethane, co-Polyoxymethylene, thermoplastic cellulose esters (Cellulose acetate propionate), acid

polylactic (PLA).

9. Composite product (2, 10, 100) according to one of claims 1 to 8, wherein the threads of the interlocking lattice are held together by a very fine thread, for example polyester, applied by sewing, knitting or weaving.

10. Composite product (2, 10, 100) according to one of claims 1 to 9, wherein the impregnating polymer is between 40% and 60% of the total mass of the product.

1. A composite product (2, 10, 100) according to one of claims 1 to 10, wherein the composite product further comprises a support (101) on which the mesh (1) impregnated is laminated, said support being by example a mat (101). 12. composite product (2, 10, 100) according to one of claims 1 to 1 1, wherein said composite product comprises two supports (101) for forming a sandwich stack, each support being on either side of said trellis .

13. composite product (2, 10, 100) according to one of claims 1 1 or 12, wherein the carrier (101) is selected from a support of woven material, a support of non-woven material, a support composed of unidirectional or multidirectional fibers, a mat, a tablecloth, a felt.

14. A composite product (2, 10, 100) according to claim 1 1 to 13, wherein said carrier (101) is prepreg of a polymer identical to or different from the polymer of said mesh (1).

15. composite product (2, 10, 100) according to one of claims 1 to 14, wherein the mesh comprises a mesh with a mesh opening greater than or equal to 1 cm, preferably between 1 cm and 6 cm, preferably between 1 cm and 3 cm. 16. composite product (2, 10, 100) according to one of claims 1 to 15, wherein the meshes are polygonal, for example rectangular or square.

17. Process for producing a composite product (2, 10, 100) according to one of claims 1 to 16, the process comprising the following steps:

- Providing polymer particles and a mesh (1) formed of son (3) intertwined, the son (3) being based on fibers, said lattice (1) comprising an upper face (6) and a lower face (7) opposed to the upper face (6), the upper face (6) being intended to receive polymer particles;

- Heating a portion of the mesh covered with particles by maintaining the upper face (6) covered with respect to a heating element (15, 23, 105), the polymer particles being heated to a temperature at least equal to the melting temperature of the polymer, said heated portion being kept flat and without contact on the upper face (6) and on the lower face (7) of said portion during heating.

18. The method of claim 17, wherein the Ms / Md ratio is between 2 and 15.

19. Method according to one of claims 17 or 18, wherein the Ms / Md ratio is between 2 and 9, preferably between 3 and 8,

preferentially 4 and 7.

20. Method according to one of claims 17 or 18, wherein the Ms / Md ratio is between 5 and 15, preferably between 7 and 13,

preferably 8 and 12.

21. The method of claim 17, wherein the deposited mass Md is between 43% and 233% of the weight of the dry mesh, preferably between 67% and 150% of the weight of the dry mesh.

22. Method according to one of claims 17 to 21, wherein the method comprises: Determine the Ms / Md ratio of the portion of mesh to be sprinkled so as to adjust the sprinkled mass Ms and cover the portion of the lattice with a mass of particles corresponding to Md;

23. Method according to one of claims 17 to 22, the dusting being carried out by a particle diffuser.

24. Method according to one of claims 17 to 23, wherein the speed of movement of the lattice during the process is between 0.5 m / min and 5 m / min, preferably between 1.0 and 2.0 m / min, for example 1.5 m / min.

25. Method according to one of claims 17 to 24, wherein the speed of movement of the mesh is constant during the dusting, preferably during dusting and heating.

26. Method according to one of claims 17 to 25, wherein the method comprises: - compressing the impregnated mesh with molten polymer at the outlet of the heating with a calendering device to promote the impregnation of the polymer in the wire, the said calendering device comprising at least one flexible roller in contact with the upper surface of the mesh, the hardness of the flexible roller being between 10 and 50 Shore A;

The method of claims 17 to 26, comprising:

- Cooling said heated portion, said portion being kept flat and without contact on the upper face (6) and on the lower face (7) of said portion during cooling, the step of

cooling taking place after the heating step.

Method according to one of claims 17 to 27, comprising: - Roll the lower face (7) and / or the upper face (6) of the heated portion on a mat (101).

29. The method of claims 17 and 28, wherein the rolling step is between the heating step and the cooling step. 30. Method according to one of claims 17 to 29, comprising:

- Preheat at least a portion of the mesh before sprinkling. 31. Method according to one of claims 17 to 30, comprising:

- Cut the mesh (1) sheet (135) or strip after the heating step. 32. Method according to one of claims 17 to 31, wherein the fibers are selected from vegetable fibers, including flax, hemp, jute, cotton, kenaf, nettle, abaca, sisal preferably flax.

33. Device (12, 102) for manufacturing a composite product (2, 10, 100) according to one of claims 1 to 16, the device (12, 102) comprising: - a sprinkling station (13, 103) comprising means for sprinkling (128) polymer particles on a lattice (1) formed of intertwined threads (3), the threads (3) being fiber-based, said lattice (1) comprising an upper face (6) and a lower face (7) opposite to the upper face (6), said sprinkling means (128) for sprinkling the upper face (6) of at least a portion of the mesh with the polymer particles to cover said upper face (6); ) with the polymer particles;

- a heating station (15, 105) positioned downstream of the sprinkling station (13, 103), said heating station (15, 23, 105) comprising a heating element (23) for heating the portion of the trellis (1 ) covered with particles, polymer particles being heated to a temperature at least equal to the melting temperature of the polymer; characterized in that the device (12, 102) comprises displacement means (17, 18, 19, 107, 108) arranged to hold said heated portion of the lattice flat and without contact on the upper face (6) and on the lower face (7) of said portion during heating.

Apparatus (12, 102) according to claim 33, the device (12, 102) comprising:

a cooling station (16, 106) downstream of the heating station for cooling said portion, said moving means (17, 18,

19, 107, 108) for maintaining said heated portion of the mesh flat and without contact on the upper face (6) and on the lower face (6) of said portion during cooling.

35. Device (12, 102) according to one of claims 33 to 34, the device (12, 102) comprising:

A rolling station (130) for rolling the upper face (6) and / or the lower face (7) of the heated portion on a mat (101).

36. Device (12, 102) according to one of claims 33 to 35, the device (12, 102) comprising: - a preheating station, upstream of the sprinkling station (13,

103), to preheat at least the portion of the mesh that will be covered with particles.

37. Device (12, 102) according to claims 35 and 36, wherein the rolling station (130) is downstream of the heating station (15, 105). 38. Device (12, 102) according to one of claims 33 to 37, the device (12, 102) comprising: - a recycling station (12, 102) downstream of the sprinkling station (13, 103).

39. Device (12, 102) according to one of claims 33 to 38, the device (12, 102) comprising: - a belt conveyor (22) for holding the mesh (1) during the dusting.

40. Device (12, 102) according to one of claims 33 to 39, the device (12, 102) comprising:

- a cutting station (134) downstream of the heating station (15, 105), preferably downstream of the cooling station (16, 106).

41. Device (12; 102) according to one of claims 33 to 40, wherein the device comprises a calendering device, said calendering device comprising at least one flexible roller in contact with the upper surface of the mesh, the hardness flexible roll between 10 and 50 Shore A.