MXPA00003361A - Method and apparatus for manufacturing a composite tape shaped from reinforcing fibres and thermoplastic material - Google Patents

Abstract

A rotationally formed container whosewall has continuous inner and outer zones are made of the same thermoplastic. Part of the second zone away from the outer wall surface also has glass fiber reinforcement helically wound along the longitudinal rotational axis of the container. The wall has a vacuum volume proportion=0.5%. Independent claims are included for the following:(a) A length of piping as above. (b) Manufacturing a container as above by helically winding a heated ribbon of glass fiber reinforced thermoplastic onto a mandrel. The ribbon is heated to above the fusion temperature of the thermoplastic in a first zone just downstream of where it contacts the mandrel. Pressure is applied in a second zone just downstream of the first zone. (c) Apparatus for performing (b). Preferred Features:The wall has a vacuum volume proportion=0.2%. The ribbon is formed by impregnating a glass fiber fabric that has been heated to between the fusion temperature and degrading temperature of the thermoplastic and then further heating it to maintain this temperature. The fibers in the fabric are parallel. The ribbon is wound so the fibers lie at 50 - 55 degrees to the pipe axis. The ribbon is softened by heating before it is applied to the mandrel.

Description

PROCEDURE FOR THE MANUFACTURE OF A COMPOSITE TAPE COMPOSED OF REINFORCING FIBERS AND ORGANIC MATTER THERMOPLASTIC DESCRIPTION The invention relates to the manufacture of a composite tape based on reinforcing fibers and thermoplastic organic matter. Composite materials based on thermoplastic material and reinforcing fibers, are widely used in the reinforcement of articles of all types, especially for manufacturing composite tubes that are intended to transport gases or liquids under pressure. According to the patent application FR 2 516 441, a method for manufacturing thin profiles comprising unidirectional continuous glass fibers immersed in a thermoplastic resin is known. The steps of the process for obtaining this type of profiling are the following: unrolling the glass threads from spools to form a layer of threads; - separation of fibers to detach them from each other due to the ensi gage that covers them; - tempering the glass fiber layer in an aqueous bath of thermoplastic material or in a fluidized bed of powder of thermoplastic material; - heating the layer to obtain the tempering mode, the evaporation of the water or the melting of the powder; hot forming of the resin-coated fibers so as to realize the desired profile. A drawback in this process is that of having to introduce for a homogeneous impregnation of the fibers by the thermoplastic material, the step of separating the fibers. This stage requires a specific device that uses several rollers, whose number and the arrangement to ensure the adequate winding angle of the layer on these, are determined by the degree of adherence of the fibers to each other. In addition, it is sometimes necessary when the degree of adhesion is too important, to provide heating means complementary to the rollers. Therefore, there is the eventuality of not perfectly separating all the fibers to allow their coating by the same thermoplastic material. On the other hand, the method uses for the impregnation, a bath of thermoplastic material that must be maintained at a constant level and whose dispersion is in constant circulation to ensure an impregnation as constant as possible. However, the means of implementation of that bath are important and heavy to control over a manufacturing chain; these are elements such as a liquid-throwing pump, a landfill for the establishment of a constant level, a storage container for the too-full one, a stirring device for the homogeneity of the contents of the bath, these elements implying a cleaning with regularity. In the variant of the impregnation device for the use of a fluidized bed, specific means are also needed, in particular a vibratory system mounted on springs to dose the amount of powder carried by the fibers. Finally, the forming device is constituted by a lower roller provided with a throat in which the layer passes and by an upper roller that serves to press the layer. In this way, the various calibers that are expected from the profiling, involve the drawback of having at the disposal several rollers carrying respective grooves of different dimensions. Consequently, this slow procedure of putting into operation, is revealed expensive and ineffective. The object of the present invention is therefore to provide a method for manufacturing a composite material based on reinforcing fibers and thermoplastic organic material that is easy to put on, as well as economically on the industrial plane. More particularly, the invention proposes, thanks to this method, a product that is presented in the form of a solid and flexible tape, of constant thickness less than 0.2 mm and constituted by continuous reinforcing threads arranged in a parallel and contiguous manner against each other. and joined together by thermoplastic material to make a transverse continuity without the presence of air; the tape has a smooth surface appearance and comprises a vacuum rate of less than 0.2%. According to the invention, the method for manufacturing a belt is characterized in that: yarns based on thermoplastic material and reinforcing fibers are routed and assembled in parallel in the form of a layer; - that layer is penetrated in an area where it is heated to a temperature that reaches at least that of the melting of the thermoplastic material without reaching the softening temperature of the reinforcing fibers; the layer is passed in a rotating impregnation device, while maintaining its temperature at a temperature of malleability of the thermoplastic material, to distribute homogeneously, the molten thermoplastic material and ensure the total impregnation of the reinforcing fibers by this; - the layer is introduced into a shaping and centering device, while maintaining its temperature at a malleability temperature of the thermoplastic material, so as to obtain a tape constituted by the contiguous approach of the threads forming a transverse continuity; - the tape is cooled to join the threads together, the thermoplastic material being set and its dimensional characteristics and its appearance are fixed to provide that composite tape of the invention. According to one characteristic, the threads that come together consist of filaments of glass and thermoplastic material mixed together.

According to another characteristic, the method consists of winding the reels of a continuous strand of reinforcing filaments and of thermoplastic material, and at the moment of the gathering of the threads in the form of a layer, in regulating the tension of the threads. Advantageously, all static electricity is removed from the wires before the layer passes into the heating zone. According to another feature, the layer is introduced into a supplementary heating zone after its passage in the rotating impregnation device. As regards the device for putting the process into operation, this device is characterized in that it comprises: means for actuating and means for gathering, in the form of a layer, the threads constituted by reinforcing filaments and thermoplastic material; means for heating said layer to a temperature that reaches at least that of the melting of the thermoplastic material, but not that of softening of the reinforcing filaments; - a rotating device for impregnating the heated layer so as to distribute homogeneously the molten thermoplastic material and guarantee the total impregnation of the reinforcing filaments by the latter; - a device for shaping and centering the layer so as to transform it into a belt; - a cooling calender of the belt that allows the thermoplastic material to be set and the wires to be joined to each other and to form the final belt. According to a characteristic, the device comprises supplementary heating means in order to store the thermoplastic material of the layer, after passing it in the impregnation device, malleable. According to another characteristic, the means for meeting the device consist of a comb whose teeth allow a parallel alignment of the threads according to regular spaces. According to another characteristic, the impregnation device comprises three heating and rotating cylinders which are arranged in a triangle and between which the layer passes; The height of separation of the cylinders is adapted to establish an appropriate pressure on the surface of the layer. Advantageously, each cylinder comprises a sheet for scraping the molten thermoplastic material deposited on the cylinder after the passage of the layer.

According to another feature, the shaping and centering device comprises a lower slice and an upper slice displaced one above the other and rotating in opposite directions; the upper slice is hyperboloid; the layer is concentrated around the central axis of passage at the moment of its passage between the two slices to provide a belt having an adjacent association of the threads against each other. Advantageously, the cooling calender of the device is constituted by two rotating cooling cylinders which are arranged one above the other and which are devoid of guiding edges; the calandria thus confers its final shape on the ribbon. From . preferably, the cooling calender comprises, in front of the cylinders, a bath in which the passing belt is immersed. Other advantages and features will now be described in relation to the drawings in which: Figure 1 is a schematic elevational view of the device for manufacturing a belt according to the invention; FIGS. 2 to 5 are sectional views of certain parts of the device of FIG. 1, respectively, of a device for regulating the tension of the wires, of the rotating impregnating device, of the shaping and centering device and of the calender of cooling. The device 1 seen in figure 1 allows the manufacture of a belt 10 according to the invention, which has a constant thickness and which is constituted by a multiplicity of the parallel threads 11 and assembled in a contiguous manner against each other. Intimately, each thread, marketed by the company VETROTES under the commercial name TWINTEKR and manufactured according to the procedure described in patent EP 0 599 695, consists of glass filaments and filaments of a thermoplastic organic material, of the polyolefin or polyester type. tangled together. The manufacturing device 1 comprises, in the form of a line and from back to front, a reel support 20 provided with several reels 2 for winding the yarn 11, a plate of eyelets 30, a device for regulating the tension of the yarns 40. , a comb 50, a static anti-electrosurgical device 60, a first furnace 70, an impregnation device 80, a second furnace 90, a smoothing and centering device 100, a calender 110, a cooling vessel 120 and a pull bench of caterpillars 130.

The spool support is of the unwinding type.

Its purpose is to provide the thread 11 of each reel 2. It is composed of a frame provided with horizontal rotary axes 21 that support each one, a reel 2. In a variant, a winding reel support can be used, but this one it induces a twist on the thread that is not constant and that goes from a round by 50 cm to a turn by 1 meter. However, this twist has the disadvantage of limiting the minimum thickness of the finished tape, not being able to descend below 0.3 mm for reels of 982 tex. Furthermore, this twisting favors the entanglement of the threads in the course of the passage over the manufacturing chain of the belt, which causes knots and / or threads 11 not parallel and not taut in the belt once it is formed, involving a fall of the mechanical properties of the tape as a finished product. Accordingly, the use of a winding reel support will be preferred, in particular to realize a thin thickness of the belt (less than 0.2 mm). However, it becomes necessary in this case, to provide a regulation device with reference 40, in figures 1 and 2.

This device 40 allows adjusting the overall tension level of the yarn layer. The buttonhole plate 30, which is also seen in Figure 2, is located in a vertical plane and parallel to the rotary axes 21 of the reel support. It allows to regroup the wires 11, which each pass through an eyelet 31, to be guided towards the voltage regulation device 40 at an angle adapted to the desired tension. In a known manner, the eyelets 31 are made of ceramic material to avoid damaging the threads as they pass through them. The voltage regulation device 40 illustrated in FIG. 2 is associated with the buttonhole plate 30. It comprises a series of cylindrical bars 41 arranged staggered one above the other and above and below which the wires run. 11 that come from the buttonhole plate 30 in order to draw identical sinusoids whose amplitude influences the tension of the threads. The bars are adjustable in height in order to be able to modify the amplitude of the sinusoids which, due to their increase, imposes a supplementary tension on the wires. At the outlet of the device 40, a comb 50 is disposed whose teeth 51 join and parallel the wires 11 in a regular space to obtain a layer 12 in the manner of the bundles of wires. Between the comb 50 and the entrance of the first furnace 70, an electrical device 60 is installed which serves to nullify any static electricity with which the wires 11 could be loaded, in order to avoid the fluffing of the yarns, which could produce its degradation in the furnace 70. The first furnace 70 as the second furnace 90, operates by convection with hot air. It could also be infrared ovens. The heating of the layer 12 by its passage in the first furnace 70 is carried out at such a temperature that upon leaving the furnace, the layer has a temperature sufficient to reach the melting temperature of the thermoplastic of the wires 11 so that melted thermoplastic, adhered and immersed in the glass filaments of the layer 12 assembly. Between and to the outside of the ovens 70 and 90, a rotating impregnation device 80 is placed which crushes the layer 12 in order to eliminate the air content between the threads, to distribute the molten thermoplastic, homogeneously over the width of the layer, and to ensure the total impregnation of the glass filaments by the thermoplastic.

The rotating impregnation device 80 shown in FIG. 3 is constituted by three cylinders 81 parallel to each other and arranged in a triangle in order to present two lower cylinders and one upper cylinder. The cylinders are heaters and reach a temperature sufficient to maintain the thermoplastic of the layer in a malleable state. The cylinders 81 are rotary: the lower ones rotate in the positive direction of passage F of the layer 12, while the upper one rotates in the opposite direction; the speeds are identical and correspond to that of the passage of the layer. The upper cylinder is adjustable in height to establish a sufficient pressure on the layer 12 in order to ensure the impregnation of the glass by the thermoplastic. The cylinders 81 that are in contact with the layer, quickly present on its surface, the deposit of a film of thermoplastic material. Advantageously, these cylinders each comprise a blade 82 which serves as a scraper in relation to its surface and whose role is, at the same time, that of preventing the formation of parasitic coils of the glass filaments and assisting in the homogeneous distribution of the molten thermoplastic. about the length of the tape. In this way, in case of surplus film thickness, this excess allows to complete the coating of the glass filaments that would eventually be insufficiently coated.

The leaves are adjustable in inclination, in order to optimize their efficiency. In a variant, in the same object of regulation of the distribution of the thermoplastic material, instead of using the sheets 82, the three cylinders are driven at a speed of rotation slightly lower than that of the passage of the layer. This solution requires not only the motorization of the cylinders 82, but also the placement of a speed control mechanism. The second furnace 90 has a set temperature such that the thermoplastic of the passing layer remains malleable. It should be noted that it would be possible to imagine a single oven in which the impregnation device 80 which resists the oven temperature would be housed. At the outlet of the second furnace, a forming and centering device 100 is arranged, which comprises, as illustrated in FIG. 4, a cylindrical lower slice 101 comprising a hyperboloid upper slice 102 slightly displaced backwards relative to the vertical of the lower slice; both slices are rotating and heating to maintain the thermoplastic of layer 12, at the malleability temperature. The purpose of the device 100 is to transform the layer 12 into a tape 13 of constant thickness constituted by the contiguous approach of the threads 11 to carry out a transverse continuity of that tape. In this way, the device 100 concentrates the layer around the central axis of the line to decrease its width that had been increased at the moment of its passage in the impregnation device 80 and re-centers it in relation to the central axis of the line of manufacture to guide the tape conveniently forward towards the calender. The gathering and guiding towards the center, is obtained by the hyperboloid shape of the upper slice 102 which, by its height adjustment, allows on the other hand, to apply a slight pressure on the upper surface of the layer to concentrate it. The rotation in the opposite direction of the slices 101 and 102 avoids, on the one hand, the draining of the thermoplastic material and, on the other hand, its accumulation which could damage the regularity of its distribution and, consequently, the thickness of the belt.

A calender 110, which is seen in Figure 5, is located forward of the device 100 in order to give the tape 13 its definite dimensional characteristics and appearance in order to have a finished tape 10. The calender 110 regulates the definitive thickness of the tape and cooled simultaneously to set the thermoplastic material giving it a smooth surface appearance. The calender is constituted by two cylinders 111 arranged one above the other and which rotate in the opposite direction, driven in rotation by the passage of the belt. The two cylinders 111 are cooled by an internal circulation of water in order to set the thermoplastic and lock the wires together. The thickness of the belt 10 is precisely controlled by the spacing imposed between the two cylinders with the help of adjustable stops 112. A pneumatic jack 113 realizes the pressure to be applied on the surface of the belt to level all variations in thickness that could happen. In this way, it acts as a closing paper for the positioning of the adjustable stops 112. It is emphasized that the calender 110 is devoid of guiding edges which, in the known calendering devices, allow to impose a width on the element to be calendered. . Indeed, in the invention, the width is defined by the number of threads 11 that are put into operation for the manufacture of the tape. The absence of edges has the advantage of not shearing the threads. The final cooling of the belt is carried out by means of a water container 120 located after the calender 110 and in which the belt 10 is immersed at the time of its passage. Subsequently to that container, a crawler-type traction bench 120 is installed, which constitutes in a known manner a means of driving the threads and the belt., exerting an effort of traction throughout the line. It imposes a speed of winding and of step of the layer and soon of the tape. Finally, the manufacturing device 1 may comprise a line termination, in a winder 140 intended to wind the tape to form a reel in order to facilitate its storage. The process for manufacturing the tape according to the invention will now be described. The example given below, makes a ribbon composed of glass and polyethylene, 90 mm wide and 0.2 mm thick; Its vacuum thickness is less than 0.2%.

The start-up of the procedure is carried out by first pulling and manually bringing each thread 11 of the reels 2 to the pull bench 130 where each thread is then held; the set of threads pass through various devices that are described above. This example is the application of 28 rovings of glass / polyethylene compound commingled yarn of Tvrin tex brand whose overall fineness of 982 tex comprises 60% glass by weight. The ovens 70 and 90 as well as the heating elements of the device 1, rise in temperature to reach the following temperatures: - oven 70: 370 ° C; - oven 90: 280 ° C; - rotating cylinders of the impregnation device 80: 290 ° C; - slices of the forming and centering device 100: 270 ° C. The pull bench 130 is put into operation, the winding of the reels 2 starts. The threads 11 pass through the eyelets 31, and then on horseback on the bars 40, and meet through the teeth of the comb 50 to form at the exit, the layer 12 of parallel threads.

The layer 12 then returns to find the device 60 which eliminates any static electricity. Then, it enters the first furnace 70, so that the thermoplastic material reaches its melting temperature. At the exit, it passes between the heating cylinders of the device 80 that allow to laminate, eliminating the air, and evenly distribute the thermoplastic material that thus covers the glass filaments. Note that the amount of thermoplastic material should not be dosed since it is directly integrated to the raw material of the tape, for its commingling with the glass filaments. The temperature of the layer reaches, after passage in that device 80, a temperature of 190 ° C. Then, the layer 12 passes through the second furnace 90 to maintain the thermoplastic material in a malleable state so that at the outlet, it passes between the slices 101, 102 of the shaping and centering device 100, to transform it into a shaped belt 13 , tightening the threads against each other and arranging them contiguously. After shaping, the belt has a temperature of 210 ° C. The tape 13 then passes between the cylinders 111 of the cold calender 110 to give it its definitive shape by setting the thermoplastic material and fixing the threads together. The tape 10 of the invention is obtained, of constant thickness and smooth appearance. The tape presents a temperature of 100 ° C at the outlet of the calender. To facilitate and accelerate the cooling of the belt assembly 10, it is immersed in the water bath 120 and becomes, at the outlet at a temperature of 30 ° C, a solid product and flexible enough to be wound by means of a winder 140 in the form of a reel for storage, transport and use facilities.

Claims (19)

1. CLAIMS 1.- Process for manufacturing a composite tape based on reinforcing fibers and organic thermoplastic material, which consists of gathering and joining together a multiplicity of continuous threads, characterized in that: - they are routed and brought together in a parallel manner, yarns based on thermoplastic material and reinforcing fibers, in the form of a layer; - that layer is penetrated in an area where it is heated to a temperature that reaches at least that of the melting of the thermoplastic material without reaching the softening temperature of the reinforcing fibers; the layer is passed in a rotating impregnation device, while maintaining its temperature at a malleability temperature of the thermoplastic material, in order to homogeneously distribute the molten thermoplastic material and guarantee total impregnation of the reinforcing fibers by this; - the layer is introduced in a shaping and centering device, while maintaining its temperature at a temperature of malleability of the thermoplastic material, so as to obtain a belt constituted by the close proximity of the threads that form a transverse continuity; - the tape is cooled to join the wires together, setting the thermoplastic material and fixing its dimensional characteristics and its appearance to provide that composite tape.
2. 2. Method according to claim 1, characterized in that the threads that are refined consist of glass filaments and thermoplastic material mixed together.
3. Method according to claim 1 or 2, characterized in that it consists in winding the reels of a continuous strand of reinforcing filaments and thermoplastic material, and at the moment of the gathering of the strands in the form of a layer, in regulating the tension of the threads.
4. 4. Method according to any of the preceding claims, characterized in that all the static electricity is eliminated from the wires, before the layer passes in the heating zone.
5. 5. Method according to claim 1, characterized in that the layer is introduced into a supplementary heating zone after its passage in the rotating impregnation device.
6. Method according to claim 1, characterized in that, at the end of the production line, the tape is wound in the form of a reel for storage.
7. 7. Device for putting into operation the process according to any of claims 1 to 6, characterized in that it comprises: - means for actuating and means for gathering, in the form of a layer, the threads constituted by reinforcing filaments and thermoplastic material; means for heating said layer to a temperature that reaches at least that of the melting of the thermoplastic material, but not that of softening of the reinforcing filaments; - a rotating device for impregnation of the heated layer so as to distribute homogeneously the molten thermoplastic material and to guarantee the total impregnation of the reinforcing filaments by the latter; - a device for shaping and centering the layer so as to transform it into a belt; - a cooling calender of the belt that allows the thermoplastic material to set and to join the threads together and form the final belt.
8. 8. Device according to claim 7, characterized in that it comprises supplementary heating means in order to keep the thermoplastic material of the layer malleable after passing it in the impregnation device.
9. 9. Device according to claims 7 and 8, characterized in that the two heating means are ovens.
10. 10. Device according to claim 7, characterized in that the device assembly means consist of a comb whose teeth allow a parallel alignment of the threads according to regular spaces.
11. 11. Device according to claim 7, characterized in that the impregnation device comprises three heating and rotating cylinders that are arranged in a triangle and between which the layer passes.; The height of separation of the cylinders is adapted to establish an appropriate pressure on the surface of the layer.
12. 12. Device according to claim 11, characterized in that each cylinder comprises a sheet for scraping the molten thermoplastic material deposited on the cylinder after the passage of the layer.
13. 13. Device according to claim 7, characterized in that the forming and centering device comprises a lower slice and an upper slice displaced one above the other and that rotate in opposite directions; the upper slice is hyperboloid; the layer is concentrated around the central axis of passage at the moment of its passage between the two slices to provide a belt having an adjacent association of the threads against each other.
14. Device according to claim 7, characterized in that the cooling calender of the device is constituted by two rotating cooling cylinders which are arranged one above the other and between which the belt passes and which are devoid of guiding edges; the calandria thus confers its final shape on the ribbon.
15. 15. Device according to claim 14, characterized in that the cooling calender comprises, in front of the cylinders, a bath in which the passing belt is immersed.
16. 16. Device according to claim 7, characterized in that the tension regulation means of the threads are provided behind the gathering means.
17. 17. Device according to claim 7, characterized in that an anti-static device is provided behind the heating means.
18. 18. Device according to claim 7, characterized in that it comprises at the end of the manufacturing line and in front of the driving means, a winder that allows to wind the tape in the form of a reel.
19. 19. Tape obtained according to the method of claim 1, characterized in that it constitutes a solid and flexible product with a smooth surface appearance, having a thickness of less than 0.2 mm and comprising a vacuum rate of less than 0.2% .