FR2784931A1 - Glass reinforced thermoplastic pipe, etc. for handling pressurized fluid has helically wound reinforcement away from wall surfaces and wall with specified maximum vacuum volume proportion - Google Patents

Abstract

A rotationally formed container whose wall 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 deg to the pipe axis. The ribbon is softened by heating before it is applied to the mandrel.

Description

 The invention relates to the manufacture of a composite tape based on reinforcing fibers and on thermoplastic organic material.

 Composite materials based on thermoplastic material and reinforcing fibers are widely used in the reinforcement of articles of all types, in particular for the manufacture of composite pipes intended to convey gases or liquids under pressure.

 There is known from patent application FR 2 516 441 a method of manufacturing thin profits comprising continuous unidirectional glass fibers embedded in a thermoplastic resin.

The process steps to obtain such benefits are:
- unwinding of glass threads from coils to form a sheet
son;
-separation of the fibers from the threads to detach them from each other in
because of the size coating them;
- soaking the sheet of glass fibers in an aqueous bath of
thermoplastic material or in a fluidized bed of powder
thermoplastic material;
-heating the sheet to obtain according to the soaking mode,
I evaporate the water or else melt the powder;
- hot forming of the sheet of fibers coated with resin
so as to achieve the desired profile.

 A disadvantage in this process is that it has to introduce, for a homogeneous impregnation of the fibers with the thermoplastic material, the step of separation of the fibers. This requires a specific device using several rollers, the number and arrangement of which ensure the correct winding angle of the sheet thereon are determined by the degree of bonding of the fibers therebetween.

 In addition, it is sometimes necessary when the degree of bonding is too great to provide additional heating means to the rollers.

 Consequently, the possibility of not separating all the fibers perfectly so as to then allow them to be coated with thermoplastic material.

 Furthermore, the method uses for the impregnation a bath of thermoplastic material which must be maintained at a constant level and the dispersion of which is in constant circulation to ensure as constant impregnation as possible. However, the means of implementing this bath are large and cumbersome to manage on a production line; these are elements such as a pump for sending liquid, a weir for establishing a constant level, a storage tank for the overflow, a stirring device for the homogeneity of the content of the bath, these elements implying regular cleaning.

 In the variant of the impregnation device for the use of a fluidized bed, specific means are also necessary, in particular a vibrating system mounted on springs for dosing the quantity of powder carried by the fibers.

 Finally, the shaping device consists of a lower roller provided with a groove in which the web runs and an upper roller used to press the web. Thus the various sizes expected from the profile imply the disadvantage of having available several rollers respectively carrying grooves of different dimensions.

 Consequently, this process, which is slow to implement, turns out to be expensive and ineffective.

 The present invention therefore aims to provide a method of manufacturing a composite material based on reinforcing fibers and of thermoplastic organic material which is easy and rapid to use, as well as economical on an industrial level.

 More particularly, the invention provides by this process a product in the form of a solid and flexible ribbon, of constant thickness less than 0.2 mm, and consisting of continuous reinforcing wires arranged in a parallel and contiguous manner against each other and joined together by thermoplastic material to achieve transverse continuity without the presence of air, the ribbon having a smooth surface appearance and comprising a void rate of less than 0.2%.

According to the invention, the method of manufacturing the ribbon is characterized in that:
- we train and collect parallel wires
of thermoplastic material and reinforcing fibers, in the form
a tablecloth;
-this sheet is made to penetrate into an area where it is heated
at a temperature reaching at least that of melting of the material
thermoplastic without reaching the softening temperature of
reinforcing fibers;
-we run the tablecloth in a rotating device
impregnation, while maintaining its temperature at a temperature
malleability of the thermoplastic material, to distribute so
homogeneous molten thermoplastic and guarantee total
impregnation of the reinforcing fibers therewith;
-the sheet is introduced into a shaping and
centering, while maintaining its temperature at a temperature of
malleability of the thermoplastic material, so as to obtain a
ribbon formed by the contiguous bringing together of the wires forming a
transverse continuity;
-the ribbon is cooled to secure the wires together by freezing the
thermoplastic material and its dimensional characteristics are fixed
and its appearance for delivering said composite tape of the invention.

 According to one characteristic, the threads which are assembled consist of continuous filaments of glass and of thermoplastic material co-mixed with one another.

According to another characteristic, the method consists in unwinding coils of a continuous wire of reinforcing filaments and of thermoplastic material, and during
of the gathering of the threads in the form of a sheet, to regulate the tension of the threads.

Advantageously, the wires are free of any static electricity
before the tablecloth passes through the heating zone.

According to another characteristic, the sheet is introduced into a zone of
additional heating after passing through the rotating device
impregnation.

As for the device for implementing the method, it is characterized in that
that it includes:
- means to train and means to gather under
sheet form the continuous threads made up of filaments of
reinforcement and thermoplastic material;
means for heating said sheet to a temperature
reaching at least that of melting of the thermoplastic material but
not that of softening of the reinforcing filaments;
-a device for impregnating the heated sheet of
so as to distribute the thermoplastic material evenly
melt and guarantee the total impregnation of the filaments
reinforcement by it;
-a device for shaping and centering the web of
so as to transform it into a ribbon;
-a ribbon cooling grille to freeze the
thermoplastic material and secure the wires together and form the
final ribbon.

 According to one characteristic, the device comprises additional heating means so as to keep the thermoplastic material of the ply malleable after the passage of the latter in the impregnation device.

 According to another characteristic, the means for assembling the device consist of a comb whose teeth allow parallel alignment of the wires 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 web runs, the separation height of the rolls being adapted to establish an appropriate pressure on the surface of the web.

 Advantageously, each cylinder has a blade for scraping the molten thermoplastic material deposited on the cylinder after passage of the sheet.

 According to another characteristic, the shaping and centering device comprises a lower roller and an upper roller offset one above the other and rotating in opposite directions, the upper roller being of hyperboloid shape, the web being concentrated around of the central scroll axis during its passage between the two rollers to deliver a ribbon having a contiguous association of the wires against each other.

 Advantageously, the cooling calender of the device consists of two rotary cooling cylinders which are arranged one above the other and have no guide edges, the calender thus giving its final shape to the ribbon.

 Preferably, the cooling calender comprises downstream of the cylinders a bath in which the moving ribbon is immersed.

Other advantages and characteristics will now be described with reference to the drawings in which:
FIG. 1 is a schematic elevation view of the device
manufacturing a ribbon according to the invention;
FIGS. 2 to 5 are side views of certain parts of the
device of FIG. 1, respectively, of a device for regulating
tension of the wires, of the rotating impregnation device, of the
conformation and centering and cooling grille.

 The device 1 visible in Figure 1 allows the manufacture of a tape 10 according to the invention which has a constant thickness and consists of a multiplicity of son 11 parallel and joined contiguously against each other. Each wire, sold by the company VETROTEX under the trade name TWtNTEX and manufactured according to the process described in patent EP 0 599 695, is made up of glass filaments and filaments of an organic thermoplastic material, of polyolefin or polyester type, intimately mixed together.

 The manufacturing device 1 comprises, in the form of a line and upstream to downstream, a creel 20 provided with several coils 2 for winding wire 11, a plate with eyelets 30, a device for regulating the tension of the wires 40 , a comb 50, an anti-static device 60, a first oven 70, an impregnation device 80, a second oven 90, a smoothing and centering device 100, a calender 110, a cooling tank 120 and a track pulling bench 130.

 Canter 20 is of the rolling type. Its purpose is to unwind the wire 11 from each coil 2. It consists of a frame provided with horizontal rotary axes 21 which each support a coil 2.

 Alternatively, a creel can be used, but this induces a twist on the wire which is not constant ranging from one turn for 50 cm to one turn for 1 m. However, this twist has the disadvantage of limiting the minimum thickness of the finished ribbon, by not being able to drop below 0.3 mm for spools of thread of 982 tex.

 In addition, this twist favors the entanglement of the threads in the course of running on the ribbon production line, which causes knots and / or threads 11 which are not parallel and not stretched in the ribbon once formed, implying a fall in properties. tape as a finished product.

 We therefore prefer the use of a rolling creel, in particular to achieve a thin thickness of tape (less than 0.2 mmm). However, it turns out to be necessary in this case to provide a regulation device, referenced 40 in FIGS. 1 and 2.

 This device 40 makes it possible to adjust the overall tension level of the ply of wires.

 The eyelet plate 30, also visible in FIG. 2, is located in a vertical plane and parallel to the rotary axes 21 of the creel. It makes it possible to group 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 voltage. The eyelets 31 are in known manner made of ceramic material to avoid damaging the wires when they pass through them.

 The tension regulation device 40 which is illustrated in FIG. 2 is associated with the grommet plate 30. It comprises a series of cylindrical bars 41 arranged in staggered rows one above the other and, on and under which the wires 11 pass. coming from the grommet plate 30 so as 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, by its increase, imposes an additional tension on the wires.

 The bars are advantageously made of brass or ceramic material to limit the phenomena of static electricity induced by the friction of the wires.

 At the outlet of the device 40, a comb 50 is arranged, the teeth 51 of which group and parallel align the wires 11 in a regular space to obtain a sheet 12 in the manner of bundles of wires.

 Between the comb 50 and the inlet of the first oven 70 is installed an electrical device 60 serving to annihilate any static electricity with which the wires 11 could be charged so as to avoid the proliferation of said wires which could otherwise cause their degradation in the oven 70.

 Both the first oven 70 and the second oven 90 operate by hot air convection. They could just as easily be infrared ovens.

 The heating of the sheet 12 by its passage in the first oven 70 is carried out at a temperature such that, on leaving the oven, the sheet has a temperature sufficient to reach the melting temperature of the thermoplastic of the wires 11 so that the latter, melted, sticks and drowns in the glass filaments of the whole of the tablecloth 12.

 Between and outside the ovens 70 and 90 is located a rotating impregnation device 80 which flattens the sheet 12 so as to expel the air contained between the wires, to distribute the thermoplastic evenly over the width of the sheet. molten, and to guarantee the total impregnation of the glass filaments by the thermoplastic.

 The rotating impregnation device 80, visible in FIG. 3, consists of three cylinders 81 parallel to each other and arranged in a triangle so as to have two lower cylinders and an upper cylinder. The cylinders are heated and reach a temperature sufficient to maintain the thermoplastic of the web in a malleable state.

 The cylinders 81 are rotary, the lower ones rotating in the positive direction of travel direction F of the web 12, while the upper one rotates in the opposite direction, the rotational speeds being identical and correspond to that of travel of the web.

 The upper cylinder is adjustable in height to establish sufficient pressure on the ply 12 so as to ensure the impregnation of the glass with the thermoplastic.

 The cylinders 81 being in contact with the sheet quickly present on their surface the deposit of a film of thermoplastic material. Advantageously, said cylinders each comprise a blade 82 acting as a doctor blade with respect to their surface and whose role is both to avoid the formation of parasitic windings of the glass filaments and to aid in the homogeneous distribution of the thermoplastic melted along the length of the ribbon. Thus, in the event of an excess of film thickness on each cylinder, this excess makes it possible to complete the coating of the glass filaments which would possibly be insufficiently coated.

 The blades 82 are adjustable in inclination so as to optimize their efficiency.

 As a variant, for the same purpose of regulating the distribution of the thermoplastic material, instead of using the blades 82, the three cylinders are driven at a speed of rotation slightly lower than that of movement of the web.

This solution requires not only the motorization of the cylinders 82 but also the installation of a speed control mechanism.

 The second oven 90 has a set temperature such that the thermoplastic of the traveling web remains malleable.

 Note that it would be possible to imagine a single oven in which would be the impregnation device 80 capable of withstanding the temperature of the oven.

 At the outlet of the second oven is placed a shaping and centering device 100 which comprises, as illustrated in FIG. 4, a cylindrical lower roller 101 and a hyperboloid upper roller 102 slightly offset upstream relative to the vertical of the roller lower, both rotating and heating to maintain the thermoplastic of the ply 12 at the malleability temperature.

 The purpose of the device 100 is to transform the ply 12 into a ribbon 13 of constant thickness formed by the contiguous bringing together of the wires 11 to achieve transverse continuity of said ribbon. Thus, the device 100 concentrates the sheet around the central axis of the line to reduce its width which had been increased during its passage through the impregnation device 80, and recenters it relative to the central axis of the line of manufacture to guide the ribbon suitably downstream towards the calender 110.

 Gathering and guiding towards the center is obtained by the hyperboloid shape of the upper roller 102 which, by its height adjustment, also makes it possible to apply a slight pressure on the upper surface of the sheet to concentrate it.

 The rotation in opposite directions of the rollers 101 and 102 prevents on the one hand, the wringing of the thermoplastic material, and on the other hand, its accumulation which could affect the regularity of its distribution and consequently, the thickness of the ribbon.

 A calender 110, visible in FIG. 5, is located downstream of the device 100 in order to give the ribbon 13 its final dimensional characteristics and appearance in order to have a finished ribbon 10. The calender 110 adjusts the final thickness tape and cools it simultaneously to freeze the thermoplastic material giving it a smooth surface appearance.

 The grille consists of two cylinders 111 arranged one above the other and rotating in opposite directions, driven in rotation by the movement of the ribbon.

 The two cylinders 111 are cooled by an internal circulation of water so as to freeze the thermoplastic and secure the wires together.

 The thickness of the tape 10 is precisely controlled by the spacing imposed between the two cylinders by means of adjustable stops 112. A pneumatic cylinder 113 achieves the pressure to be applied to the surface of the tape to level all variations in thickness that could arise. It thus plays a role of locking the positioning of the adjustable stops 112.

 It is pointed out that the calender 110 is devoid of guide edges which, in known calendering devices, make it possible to impose a width on the element to be calendered. In fact, in the invention, the width is defined by the number of wires 11 used for the manufacture of the ribbon. The absence of edges has the advantage of not shearing the wires.

 The final cooling of the ribbon is carried out by means of the water tank 120 located after the calender 110 and in which the ribbon 10 is immersed during its running.

 After this tank is installed a crawler pulling bench 130 which in known manner constitutes a means of driving the wires and the tape, exerting the tensile force along the line. It imposes the speed of unwinding and running of the sheet then of the ribbon.

 Finally, the manufacturing device 1 can comprise, at the end of the line, a winder 140 intended to wind the ribbon to form a reel so as to facilitate its storage.

 The method of manufacturing the ribbon according to the invention will now be described. The example given below produces a composite ribbon of glass and polyethylene, 90 mm wide and 0.2 mm thick, its void rate being less than 0.2%.

 The process is started first by pulling and manually bringing each wire 11 from the reels 2 to the pulling bench 130 where each wire is then kept pinched, all of the wires passing through the various devices described above. In this example, this is an application of 28 rovings of composite glass-polyethylene yarn of the TwintexM brand) whose overall title 982 Tex comprises 60% glass by weight.

The ovens 70 and 90 as well as the heating elements of the device 1 are raised in temperature to reach the temperatures:
- oven 70: 370 C;
- oven 90: 280 C;
- rotary cylinders of the impregnation device 80: 290 C;
-galets of the conformation and centering device 100: 270 C.

 The pulling bench 130 is put into operation, the unwinding of the coils 2 begins.

 The wires 11 pass through the eyelets 31, then straddle the device 40, and are gathered through the teeth of the comb 50 to form the sheet 12 of parallel wires at the outlet.

 The sheet 12 then meets the device 60 which eliminates any static electricity.

 It then enters the first oven 70 so that the thermoplastic material reaches its melting temperature. At the outlet, it passes between the heating cylinders of the device 80 which make it possible to laminate it while expelling the air, and to distribute the thermoplastic material uniformly which thus coats the glass filaments. Note that the quantity of thermoplastic material is not to be dosed since it is directly integrated into the raw material of the ribbon by its bonding with the glass filaments. The temperature of the sheet reaches after the passage through this device 80 a temperature of 190 C.

 Then the sheet 12 passes through the second oven 90 to maintain the thermoplastic material in a malleable state so that at the outlet, when it passes between the cylinders 102 of the shaping and centering device 100 to transform it into a ribbon 13, shaped as tightening the wires against each other and arranging them contiguously. After conformation, the ribbon has a temperature of 210 C.

 The ribbon 13 then passes between the cylinders 111 of the cold calender 110 to give it its final shape by freezing the thermoplastic material and by joining the wires together. The ribbon 10 of the invention of constant thickness and smooth appearance is obtained. The ribbon has a temperature of 100 ° C. at the outlet from the grille.

 To facilitate and accelerate the cooling of the entire ribbon 10, it is immersed in the water bath 120 and becomes at the outlet, its temperature being 30 C, a solid product and flexible enough to be wound by means of 'A winder 140 in the form of a reel for ease of storage, transport and use.

Claims (19)

 1. Method for manufacturing a composite ribbon (10) based on reinforcing fibers and on thermoplastic organic material, consisting in gathering and joining together a multiplicity of continuous wires (11) characterized in that:  -We train and collect wires in parallel  base of thermoplastic and reinforcing fibers, under the  form of a sheet (12);  -this sheet (12) is made to penetrate into an area where it is  heated to a temperature reaching at least that of melting the  thermoplastic material without reaching the temperature of  softening of the reinforcing fibers;  -we run the tablecloth (12) in a rotating device  impregnation (80), while maintaining its temperature at a  mailability temperature of the thermoplastic, to distribute  homogeneously the molten thermoplastic material and guarantee the  total impregnation of the reinforcing fibers by it;  - the web (12) is introduced into a shaping device and  centering (100), while maintaining its temperature at a  malleability temperature of the thermoplastic material, so that  obtaining a ribbon (13) formed by the contiguous bringing together of the wires  (11) forming a transverse continuity;  -on cooling the ribbon (13) to secure the son together  freezing the thermoplastic material and fixing its characteristics  dimensions and its appearance for delivering said composite tape (10).  2. Method according to claim 1, characterized in that the son (11) which are assembled consist of continuous filaments of glass and of thermoplastic material cl-mles between them.  3. Method according to claim 1 or 2, characterized in that it consists of unwinding coils of a continuous wire of reinforcing filaments and of thermoplastic material, and when gathering the son in the form of a sheet, regulating the tension sons.  4. Method according to any one of the preceding claims, characterized in that the wires (11) are rid of any static electricity before the passage of the sheet (12) in the heating zone.  5. Method according to claim 1, characterized in that the sheet is introduced (12) in an additional heating zone after it has passed through the rotating impregnation device (80).  6. Method according to claim 1, characterized in that at the end of the production line, the ribbon (10) is wound in the form of a reel for its storage.  7. Device for implementing the method according to any one of claims 1 to 6, characterized in that it comprises:  means (130) for training and means (50) for  bring together in the form of a sheet (12) the continuous threads (11) made up of  reinforcing filaments and thermoplastic material;  means (70) for heating said sheet (12) to a  temperature reaching at least that of material melting  thermoplastic but not that of softening the filaments of  enhancement ;  -a rotating impregnation device (80) of the heated sheet  so as to distribute the thermoplastic material evenly  melt and guarantee the total impregnation of the filaments  reinforcement by it;  -a device for shaping and centering (100) the web  (12) so as to transform it into a ribbon (13);  -a cooling grille (110) of the ribbon (13) allowing  freeze the thermoplastic material and secure the wires (11) between  them and form the final ribbon (10).  8. Device according to claim 7, characterized in that it comprises additional heating means (90) so as to keep the thermoplastic material of the ply (12) malleable after the passage of the latter in the impregnation device (80).  9. Device according to claims 7 and 8, characterized in that the two heating means (70,90) are ovens.  10. Device according to claim 7, characterized in that the gathering means (50) consist of a comb whose teeth (51) allow parallel alignment of the wires (11) according to regular spaces.  11. Device according to claim 7, characterized in that the impregnation device (80) comprises three cylinders (81) heating and rotating which are arranged in a triangle and between which the web (12) runs, the height of separation of the cylinders being adapted to establish an appropriate pressure on the surface of the web.  12. Device according to claim 11, characterized in that each cylinder (81) comprises a blade (82) for scraping the molten thermoplastic material deposited on the cylinder after passage of the web.  13. Device according to claim 7, characterized in that the shaping and centering device (100) comprises a lower roller (101) and an upper roller (102) offset one above the other and rotating in opposite directions, the upper roller being of hyperboloid shape, the ply (12) being concentrated around the central axis of travel during its passage between the two rollers to deliver a ribbon (13) having a contiguous association of the wires against each other others.  14. Device according to claim 7, characterized in that the cooling calender (110) consists of two revolving cooling cylinders which are arranged one above the other and between which the ribbon (13) runs, and which have no guide edges, the calender conferring its final shape on the ribbon (10).  15. Device according to claim 14, characterized in that the cooling calender (110) comprises downstream of the cylinders a bath (120) in which the ribbon (10) is immersed in movement.  16. Device according to claim 7, characterized in that tension regulation means (40) of the wires (11) are provided upstream of the gathering means (50).  17. Device according to claim 7, characterized in that an anti-static device is provided upstream of the heating means (70).  18. Device according to claim 7, characterized in that it comprises at the end of the production line and downstream of the drive means  (130) a winder (140) for winding the ribbon (10) in the form of a reel.  19. Ribbon obtained according to the method of claim 1,  characterized in that it constitutes a solid and flexible product, of surface appearance  smooth, having a thickness of less than 0.2 mm and comprising a rate of  vacuum less than 0.2%.