FR2876945A1 - Reinforced thermoplastic component e.g. for motor vehicle interior load-bearing panel has main body and reinforcing elements of same or compatible thermoplastics - Google Patents

Abstract

The component consists of a main body (1) comprising a first thermoplastic matrix, and at least one reinforcing element (2) of a material comprising a second thermoplastic matrix with continuous parallel fibres. The first and second matrices are of the same or compatible thermoplastics welded together or made in one piece. The reinforcing elements are in the form of elongated profiles with glass, mineral, vegetable or synthetic fibres lying parallel to their axes and making up 20 - 80 per cent of their weight. They have a Young modulus at 23 degrees C of between 10000 and 50000 MPa and a permitted stress of between 200 and 900 MPa.

Description

REINFORCED THERMOPLASTIC PIECE

  The present invention relates to a reinforced thermoplastic piece adapted to withstand high loads. Such a part may be intended for use as an automobile, trolley or other device requiring localized reinforcement to withstand heavy loads.

  Certain automobile interior and trunk parts, such as load floors or rear shelves, for example, must be able to withstand heavy loads such as luggage and are subject to significant mechanical stresses, in particular stiffness, residual arrow and creep resistance. To satisfy these mechanical constraints, it is known to make these parts in materials having high Young's moduli, such as thermosetting materials.

  These thermosetting materials with a high Young's modulus, however, have the disadvantage of not being easily recycled. In addition, the aforementioned parts are often visible in a motor vehicle, they are also subject to aesthetic constraints. It is then binding for the designer to be limited in his choice of materials to only materials with sufficient mechanical qualities.

  A known solution for producing this type of part, called semi-structural, is to manufacture them in materials that do not have a particularly high Young's modulus, and to obtain the desired rigidity thanks to the geometry of the part. For example FR-A-2,734,201 discloses a double-shell tablet consisting of two walls secured to one another at multiple points or surface portions so as to provide vacuum volumes between said walls. It is the multiplicity of points or portions of contact surfaces between the walls which contributes to stiffening the assembly. Such a mono-material tablet can easily be recycled. But such tablets have a large size in thickness, which is not always compatible with the available space in the vehicle. In particular for stiffening a load floor, the necessary thickness is such that this solution can not be applied.

  Another known solution is to make this type of semi structural part with added reinforcements. The part is then composed of two assembled elements, namely a part body, such as a plate made of a light material satisfying the aesthetic constraints but without particular stiffness constraints, and reinforcements made of a high Young's modulus material. . This type of part is frequently used in vehicle trunks, for example for rear shelves made of polypropylene (PP) with metal reinforcements.

  Such parts fully satisfy rigidity constraints. However, the use of two families of materials complicates the recycling of these parts: the part must be dismantled, the materials must be separated, so that everyone follows the appropriate recycling path.

  In addition, there are reinforcement elements of thermosetting material having a high Young's modulus produced by pultrusion of a composite material comprising glass fibers. Such elements are for example described in the patent application FR-A-2 483 343 for a bumper and in the patent application EP-A-0 980 801 for a wiper reinforcement. The composite materials used in these applications are obtained by pultrusion of glass fibers impregnated with resin. These reinforcing elements, however, do not meet any aesthetic constraint and are assembled with intermediate parts to the vehicle parts they reinforce. Such composite elements can not be assembled directly with a thermoplastic part to be reinforced.

  There is therefore a need to produce reinforced thermoplastic parts that are aesthetic, light, recyclable, limited space and simplified manufacturing.

  For this purpose, the invention provides a thermoplastic part comprising: a body made of a material comprising a first thermoplastic matrix; at least one reinforcing element consisting of a material comprising a second thermoplastic matrix and continuous fibers substantially parallel to each other; the first and second thermoplastic matrices being materials of the same family and said at least one reinforcing element being irreversibly associated with the body of the workpiece.

  According to the embodiments, the thermoplastic component of the invention may comprise one or more of the following characteristics: the family of the first and second matrices is chosen from polypropylenes; the first and second thermoplastic matrices are made of the same material; the reinforcing element is welded to the body of the piece; the reinforcing element is integral with the body of the part; the reinforcing element has the shape of an elongate section, the continuous fibers being substantially parallel to the longitudinal axis of the reinforcing section; The fibers comprise between 20% and 80% by weight of the reinforcing element; the fibers of the reinforcing element are chosen from glass fibers, mineral fibers, fibers of vegetable origin and synthetic fibers; - The reinforcing element has a Young's modulus at 23 C between 10000 and 50000 MPa; the reinforcing element has a permissible stress of between 200 and 900 MPa; the reinforcing element comprises a cladding comprising a thermoplastic material; the reinforcing element has a transverse profile in the form of, I, T, U, V, W, square, rectangle or circle; The invention also relates to an assembly comprising: a thermoplastic part according to the invention; - a covering surrounding the room.

  According to the embodiments, the dressing is a box or a fabric. The invention also provides a method of manufacturing a reinforced thermoplastic member, comprising the steps of: - providing a workpiece body comprising a first thermoplastic matrix; providing at least one reinforcing element comprising substantially parallel continuous fibers incorporated in a second thermoplastic matrix, the first and second thermoplastic matrices being materials of the same family; irreversibly associating said at least one reinforcement element with the body to constitute a reinforced part.

  According to the embodiments, the method of the invention may comprise one or more of the following features: the step of producing the body consists in injecting a thermoplastic material into a mold; the step of producing the reinforcing element comprises the steps of joining several strands of fibers to be stretched through a die and introducing a thermoplastic material into the die; the step of providing the reinforcing member comprises steps of joining a plurality of fiber strands impregnated with thermoplastic material and stretching said fiber strands through a die; The step of producing the reinforcing element comprises the steps of joining several strands of fibers and a wire of material. thermoplastic and to stretch said strands and said wire simultaneously through a die; the step of associating the reinforcing element with the body comprises a welding step; the step of combining the reinforcing element with the body comprises a heat-sealing step; the step of combining the reinforcing element with the body is conducted simultaneously with the step of producing the body of the part and comprises the steps of arranging said at least one reinforcing element in a mold corresponding to the body of the piece and thermocompress a thermoplastic material deposited in the mold.

  The invention also relates to the use of a thermoplastic component according to the invention or an assembly according to the invention for constituting at least partially an automotive part or at least partially a carriage part.

  Other features and advantages of the invention will appear on reading the following detailed description of the embodiments of the invention, given by way of example only and with reference to the drawings which show: FIG. schematic perspective view of a reinforced part according to the invention; - Figure 2, a detailed schematic view of a reinforcing element of the part of Figure 1; - Figures 3 to 6, diagrams of different modes of association of the reinforcing elements with the body of the room; FIG. 7 is a detailed schematic view of a method of associating a reinforcing element with the body of the part.

  The invention provides a thermoplastic component comprising a body and at least one reinforcing element. The body is made of a material comprising a first thermoplastic matrix and may have the desired aesthetic and geometric characteristics for the part. The reinforcing element is made of a material comprising a second thermoplastic matrix and continuous fibers substantially parallel to each other. The reinforcing element is directly and irreversibly associated with the body of the room.

  The first and second thermoplastic matrices are chosen such that a direct and irreversible association can be achieved between the reinforcing elements and the R-Patent. 233/24 - 09/10/04 - 09.10 4/14 body of the part ; in particular, the first and second thermoplastic matrices are materials of the same family. The manufacture of the reinforced part is thus simplified, as well as its recycling.

  Figure 1 is a perspective view of a reinforced part according to the invention.

  Such a piece could represent a rear shelf of a motor vehicle. The thermoplastic part comprises a body 1 made of a material comprising a thermoplastic matrix, for example polypropylene or any other polyolefin. Additives, such as color pigments, anti-UV fillers, texturizing agents, or the like, can be added to the thermoplastic matrix of the body. The body 1 of the piece is shown as a tray, but it is understood that any other form could be concerned by the invention.

  The part also comprises reinforcement elements 2 made of thermoplastic material. The reinforcing elements consist of a material comprising a thermoplastic matrix and continuous fibers substantially parallel to each other. The thermoplastic matrix of the reinforcing elements is chosen from the same family as the matrix constituting the body of the part, for example polypropylene, polyamide or any other thermoplastic material. It is understood that the same material can be used for the thermoplastic matrices of the reinforcing elements and the body of the part. It is thus possible to achieve a direct and irreversible association between the reinforcing elements and the body of the part. The part can also be recycled without dismantling.

  The term "direct and irreversible association" is understood to mean an assembly that has an adhesion such that the part breaks if one tries to separate the reinforcing elements from the body of the part. For example, the reinforcing elements 2 may be welded or heat-sealed to the body 1 of the part or be made in one piece with the body of the part. Monoblock in this context means that the reinforcing elements are assembled during the forming step of the body of the part.

  The reinforcing elements 2 have the shape of an elongated section, that is to say with a length greater than the width and height, for example with a length equal to at least three times the width and height. The fibers incorporated in the matrix of the reinforcing elements are arranged substantially parallel to the longitudinal axis of this profile.

  The fibers incorporated in the matrix of the reinforcing elements are said to be continuous, that is to say that they extend generally over the entire length of the reinforcement profile; they are not incorporated in flakes or pieces in the thermoplastic matrix. The fibers are also said to be substantially parallel to each other, that is to say that they are not entangled.

  The fibers of the reinforcing elements may be glass fibers. It is also possible to envisage using other types of fibers, such as mineral fibers such as carbon, plant-based fibers such as linen, jute, hemp, sisal, or synthetic fibers such as aramid. The choice of reinforcing fibers depends on the expected mechanical performance of the part. The proportion by mass of glass fibers in each reinforcing element is between 20% and 80% by weight. The thermoplastic matrix in which the fibers are embedded may be polypropylene or any other polyolefin, polyester, polyamide or any other thermoplastic material.

  A reinforced thermoplastic component has also been obtained, the reinforcing elements having, by the presence of the fibers, a Young's modulus of between 10,000 and 50000 MPa, ie a Young's modulus much higher than that of the body of the part which can be between 500 and 7000 MPa. In addition, the allowable stress, that is to say the breaking strength of the reinforcing element, is between 200 and 900 MPa. By way of comparison, mention may be made of the values of the steel which has a Young's modulus of 200,000 MPa and a permissible stress of 500 MPa. The combination of these two characteristics, namely resistance to stress and elasticity, makes it possible to give the reinforced part a role of throttle limiter which finds particularly advantageous applications for automobile parts.

  In case of shock, the acceleration is not directly transmitted to people, goods or mechanical parts in contact with the reinforced part because the reinforced part resists and absorbs part of the shock. Such reinforced parts thus make it possible to improve the protection of persons and goods in contact with the part and makes it possible to reduce the dimensioning of adjacent parts by limiting the forces transmitted. The Young's modulus ratio / allowable stress of the reinforcement elements is more favorable than a metallic reinforcement for the control of the forces. The protection of people and the dimensioning of the surrounding structures are thus improved.

  According to one embodiment, illustrated in Figure 2, the reinforcing elements 2 can be sheathed. The reinforcing elements 2 may be at least partially coated by a sheath 3 made of a thermoplastic material. The cladding material comprises a thermoplastic matrix compatible with the thermoplastic matrix and the reinforcing elements, that is to say of the same organic family. The cladding material 3 may comprise additives, but is fiber-free.

  The reinforcing element then consists of a structural core 2 and an aspect skin 3. This skin can improve the sensory qualities of the reinforcements, particularly on the tactile plane, for example for a soft touch , and visually, for example a translucent cladding. In addition to these sensory advantages, the cladding 3 can improve the mechanical properties of the reinforcement 2, in particular by increasing the permissible stress by the reinforcement in a direction perpendicular to the direction of the fibers, which improves the cohesion of the reinforcement.

  Figures 3 to 6 illustrate several ways of combining the reinforcements 2 with the body 1 of the room. It should be noted that the reinforcing elements 2 have a generally elongated shape, that is to say that their length is much greater than their width and height, and the cross section of the reinforcing elements 2 remains substantially constant over the entire length but the shape may vary. For example, transverse profiles in the form of Sl (Omega), I, T, U, V, W, circle, square, rectangle or any other parallelepiped shape may be envisaged.

  In FIG. 3, the body 1 is a substantially flat piece and the reinforcing elements 2 have a T-shaped cross-section, the horizontal bar of the T being welded to the body 1.

  In FIG. 4, the body 1 of the part is a part having ribs 11 and the reinforcing elements 2 have a T-shaped cross section, the horizontal bar of the T being welded to the bottom of the rib 11 of the body 1.

  In FIG. 5, the body 1 is a part having grooves 12 and the reinforcing elements 2 have an inverted T-shaped cross section, the vertical bar of the T being housed in the groove 12 of the body 1 and the horizontal bar of the T welded on the end of the grooves 12.

  In Figure 6, the body 1 of the part is a double shell plate 13 inside which are integrated the reinforcing elements 2 having an inverted V-shaped cross section. The reinforcements 2 are preferably welded on either side of the shell 13. The body 1 of the part may also comprise spacers 14 added between the walls of the double shell 13.

  In Figure 7, a portion of the body 1 has a non-planar shape, possibly a three-dimensional shape, with grooves 12. The reinforcing member 2 has a rectangle-shaped cross section welded to the end of the grooves .

  Moreover, one or more reinforcements 2 may be curved longitudinally, although this is not illustrated in the figures, for example to fit a body 1 curved. For example, a reinforcement 2 having a thickness of 1 to 6 mm and any width may be curved over all or part of the length of the workpiece body.

  The geometry of the body 1, that of the reinforcing elements 2 and the resulting association geometries are left to the appreciation of the skilled person, according to the flexural strength values to be obtained. The geometry of the reinforcements is thus chosen as a function of the mechanical stresses to be respected, and in particular the flexural strength to be obtained for the first time. room. The number of reinforcements, their locations on the body also depend on the value to be respected in flexion under load.

  In addition, during the forming of the body 1 of the part, by injection into a mold for example, the body obtained can be deformed with respect to the expected shape. The combination of the reinforcing elements 2 to the body 1 then makes it possible to compensate for these deformations during the welding of the elements 2.

  It should be noted that the reinforced part according to the invention, comprising a body 1 of part and one or reinforcements 2, can be covered, totally or partially, a covering. Such a covering may be a box made of thermoplastic material or fibrous material or any other insulating material; the covering may also be a fabric wrapping the reinforced part, such as a felt for example.

  The reinforced thermoplastic part according to the invention can be manufactured in the following manner.

  A body 1 comprising a thermoplastic thermoplastic injection molding, blowing, thermoforming, rotational molding, thermocompression, or other common technology for forming parts made of thermoplastic materials is produced. The dimensions and shapes of the body of the part can be very variable according to the envisaged applications.

  The material of the body 1 of the part may contain mineral fillers, such as talc or glass, or vegetable. The fillers may be natural cellulosic fibers, such as flax, jute or sisal, in proportions varying between 30% and 70%, and preferably 50/50. In a variant, the body 1 comprises at least one layer of nonwoven material, a felt for example, and a layer of thermoplastic material, those two layers being bonded by heating then compacting. The material thus obtained has a Young's modulus of between 500 and 7000 MPa at 23 ° C. (1 MPa = 1 N / mm 2).

  At least one reinforcement element 2 is also made comprising substantially parallel continuous fibers incorporated in a thermoplastic matrix.

  For example, the reinforcing elements 2 can be obtained by pultrusion. Several continuous fiber strands are joined in parallel and introduced into a die. A thermoplastic material may be introduced into the die while the fibers are stretched to form the reinforcing member 2. The shape of the cross section of the reinforcing member 2 is a function of the size of the die used. It is also possible to use a composite yarn joining fiber and thermoplastic fiber strands as described in the patent application FR-A-2,638,467 and heating the line upstream of the die to soften the thermoplastic material in order to: 23100 \ 23148.doc - 27/10/04 - 09:10 - 8/14 to incorporate the fibers into the plastic. It is also possible to use fiber strands and a wire of thermoplastic material introduced into the die at the same time as the fiber strands. The thermoplastic material is heated before introduction into the die and the fibers are incorporated into the plastic at the outlet of the die.

  In the case of a sheathed reinforcing element, as illustrated in FIG. 2, a profile is firstly formed in which the fibers and the thermoplastic material are brought together in parallel, and this profile is introduced into a calibrated die into which at the same time at least one second molten thermoplastic material in contact with the profile to form the cladding.

  The reinforcing elements are then associated with the body to form the reinforced part. A direct and irreversible association can be obtained by welding, preferably without contact such as infrared radiation welding.

  In contactless welding, the welding is done by radiation. Energy in the form of heat is provided at the contact surface to cause surface melting of the material. The energy source may be a laser, an infrared emissive wire, an ultrasonic or high frequency emitter, or the like. When the parts to be welded come into contact, the contact surfaces interpenetrate, which is reflected at the molecular level by entanglement of the polymer chains. At the time of cooling, the polymer chains adopt a new three-dimensional structure thus ensuring a direct and irreversible association of the welded parts. The welding is done only by merging the two parts to be assembled, without adding additional materials.

  The combination of the reinforcing elements 2 with the body 1 of the part can be achieved by any other suitable welding technique, such as mirror welding or vibration welding for example, and can also be done by gluing, especially by gluing. hot (hotmelt). However, bonding welding is preferred because welding does not require any addition of external material, whereas bonding requires a coating of thermoplastic adhesive on at least one of the parts to be assembled.

  If the reinforcing elements 2 are sheathed 3, the welding or bonding will be done between this thermoplastic sheath 3 and the body 1.

  In a particular embodiment, when the body 1 is made by thermoforming or thermocompression, the association of the reinforcing elements 2 to the body can be done directly during the shaping of the body. This is called a one-step process, or one shot.

  The reinforcing elements 2 are manufactured according to one of the aforementioned embodiments or any other appropriate mode. The elements 2 are then deposited in the mold intended to form the body 1 of the part. The material constituting the body is heated above its melting point and deposited in the cold mold. The body material is then thermocompressed in the mold to form the body while simultaneously assembling the reinforcing members. The surface of the reinforcements 2 intended to be adjacent to the workpiece body can be reactivated, that is to say heated, before they are put into place in the mold to improve the adhesion between the reinforcements and the workpiece body.

  The reinforced thermoplastic part according to the invention can be used for the following applications.

  The part can be at least partially a car part, such as a tailgate, a rear shelf, a trunk floor, a cockpit floor, a screen under engine, a door, roof bars, anti-extrusion bars , or any other part having to meet a specification of mechanical strength or impact resistance.

  The part may also be at least partially a carriage part, for example a bottom or a handle, in particular a telescopic handle.

  The number of reinforcements and their location depends directly on the desired rigidity for the semi-structural part. For example, a self-supporting tablet of size 1000 mm * 500 mm * 65 mm will thus be advantageously stiffened by two elements of at least 900 mm long placed at 200 mm distance from one another.

  R: \ Patents \ 23100 \ 23148.doc - 27/10/04 - 09:10 - 10/14

Claims (1)

11 CLAIMS   A thermoplastic component comprising: a body (1) made of a material comprising a first thermoplastic matrix; - At least one reinforcing element (2) consisting of a material comprising a second thermoplastic matrix and continuous fibers and substantially parallel to each other; the first and second thermoplastic matrices being materials of the same family and said at least one reinforcing element (2) being irreversibly associated with the body of the workpiece (1).   2. The thermoplastic part of claim 1, characterized in that the family of the first and second matrices is selected from polypropylenes.   3. The thermoplastic part of claim 1 or 2, wherein the first and second thermoplastic matrices are made of the same material.   4. The thermoplastic part of one of claims 1 to 3, characterized in that the reinforcing element is welded to the body of the piece.   5. The thermoplastic part of one of claims 1 to 3, characterized in that the reinforcing element is integral with the body of the part.   6. The thermoplastic part of one of claims 1 to 5, characterized in that the reinforcing element (2) has the shape of an elongated section, the continuous fibers being substantially parallel to the longitudinal axis of the profile of reinforcement.   7. The thermoplastic part of one of claims 1 to 6, characterized in that the fibers comprise between 20% and 80% by weight of the reinforcing element.   8. The thermoplastic part of one of claims 1 to 7, wherein the fibers of the reinforcing element are selected from glass fibers, mineral fibers, plant fibers and synthetic fibers.   9. The thermoplastic part of one of claims 1 to 8, characterized in that the reinforcing element has a Young's modulus at 23 C between 10000 and 50000 MPa.   The thermoplastic part of claim 9, characterized in that the reinforcing element has a permissible stress of between 200 and 25.degree. and 900 MPa.   11. The thermoplastic part of one of claims 1 to 10, characterized in that the reinforcing element (2) comprises a cladding (3) comprising a thermoplastic material.   12. The thermoplastic part of one of claims 1 to 11, characterized in that the reinforcing element (2) has a transverse profile in the form of Sl, I, T, U, V, W , square, rectangle or circle.   13. An assembly comprising: - a thermoplastic part according to one of claims 1 to 12; - a covering surrounding the room.   14. The assembly of claim 13, wherein the dressing is a box.   15. The assembly of claim 13, wherein the dressing is a fabric.   16. A method of manufacturing a reinforced thermoplastic part, comprising the steps of: - producing a body (1) of part comprising a first thermoplastic matrix; - Making at least one reinforcing element (2) comprising substantially parallel continuous fibers incorporated in a second thermoplastic matrix, the first and second thermoplastic matrices being materials of the same family; irreversibly associating said at least one reinforcement element with the body to constitute a reinforced part.   17. The method of claim 16, wherein the step of forming the body (1) comprises injecting a thermoplastic material into a mold.   The method of claim 16 or 17, wherein the step of providing the reinforcing member (2) comprises steps of joining a plurality of fiber strands to be drawn through a die and introducing a thermoplastic material into the sector.   The method of claim 16 or 17, wherein the step of providing the reinforcing member (2) is in accordance with the present invention. ) comprises steps of joining several fiber strands impregnated with thermoplastic material and stretching said fiber strands through a die.   The method of claim 16 or 17, wherein the step of providing the reinforcing member (2) comprises steps of joining a plurality of fiber strands and a thermoplastic wire and stretching said strands and said wire simultaneously through a die.   21. The method of one of claims 16 to 20, wherein the step of associating the reinforcing member with the body comprises a welding step.   The method of one of claims 16 to 20, wherein the step of associating the reinforcing member with the body comprises a heat sealing step.   23. The method of one of claims 16 to 20, wherein the step of associating the reinforcing member with the body is conducted simultaneously with the step 15 of making the body (1) of the piece and comprises the steps of arranging said at least one reinforcing element in a mold corresponding to the body of the workpiece and thermocompressing a thermoplastic material deposited in the mold.   24. Use of a thermoplastic part according to one of claims 1 to 12 or an assembly according to one of claims 13 to 15 to at least partially form an automobile part.   25. The use of the thermoplastic part according to claim 24, wherein the automotive part is selected from a boot lid, a rear shelf, a boot floor, a cockpit floor, a screen under engine, a door, roof bars, anti-extrusion bars.   26. Use of a thermoplastic part according to one of claims 1 to 12 or an assembly according to one of claims 13 to 15 to form at least partially a carriage part.   27. The use of the thermoplastic part according to claim 26, wherein the carriage part is selected from a bottom or a handle.   R: \ Patents \ 23100 \ 23148.doc - 27/10/04 - 09:10 - 13/14