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    • 专利摘要:
    The present invention relates to a continuous device (1) for impregnating in a single step strands or ribbons of natural fibers (100), in particular flax, with a specific aqueous dispersion of polymer for consolidating the fibers at the core of the bundle fibers and improve their mechanical strength without the need for twisting, comprising the following means: - means (10) for elongation by stretching the wick or ribbon of natural fibers to the desired titration, - means (20) impregnating the fibers with the aid of the aqueous dispersion to guarantee complete impregnation of the filaments by the latter, means (30) for conformation / calibration of the fibers, means (40) for drying the fibers, and means (50) for conditioning the fibers in order to transform them into yarn or ribbon.
    公开号:FR3020776A1
    申请号:FR1454199
    申请日:2014-05-12
    公开日:2015-11-13
    发明作者:Guy Dehondt；Edouard Philippe
    申请人:DEHONDT TECHNOLOGIES；
    IPC主号:
    专利说明:

    [0001] The present invention relates to a device for impregnating strands or ribbons of natural fibers, in particular flax with a specific aqueous dispersion of polymer to consolidate the fibers in the core of the fiber bundle and improve their mechanical strength without the need for twisting. The invention also relates to the treated fibers and their use in composite materials. The natural fibers of flax, hemp or sisal and in particular flax, are not continuous but discontinuous fibers interconnected by transverse fibrils ensuring their holding. However, this outfit is quite weak and makes complex their implementation and their use in finished products. It is therefore interesting and even necessary to strengthen the mechanical strength of the strands or son or ribbons of natural fibers, unlike the case of glass or carbon fibers that are continuous. Regarding the use of such natural fibers in textiles, it is known to twist them so as to constitute a thread having sufficient mechanical strength.
    [0002] The challenge is to obtain this improved mechanical strength of the fiber lock but without twisting the fibers. When one seeks to make a natural reinforcement to manufacture composites, one seeks to preserve as much as possible the intrinsic qualities of natural fibers, in particular flax fibers. Thus, it is recommended not to twist the fibers. In this case, the fiber locks, that is to say bundles of fibers or ribbons of natural fibers, are then made of fibers for technical use having better mechanical properties than twisted textile fibers, because they were not damaged by the twisting step. Therefore, obtaining a wick or a ribbon of natural technical fibers strong enough not to break during their manufacture requires the realization of wicks or fiber ribbons of heavy weight (expressed in tex), significantly more important than what is done with fiberglass or carbon fiber. As a reminder, a tex corresponds to a weight or linear mass (per unit length) equal to 1g / km or 10-6 kg / m. This greater desired basis weight results in unidirectional fibrous reinforcements or nonwovens, or coarser fabrics, with imperfections and thus affecting the ultimate strength of natural fiber composites such as flax fibers. It is also impossible, with this type of reinforcement based on natural fibers, to produce lightweight sandwich panels comprising natural fiber composite skins, in particular flax fibers, of very small thickness.
    [0003] Thus, the purpose of a ribbon or wick with a lower basis weight in flax fibers is to produce quasi-continuous natural fiber composites of greater mechanical strength and to produce lightweight sandwich panels comprising composite reinforcements based on technical natural fibers, more efficient than those made from textile fibers. There is therefore a need to consolidate and strengthen said fiber locks without resorting to twisting the fibers and seeking a binder capable of penetrating the core of the locks of said fibers to bind the fibers to each other with sufficient cohesion to improve the mechanical strength of the wick. Thermoplastic composites already have the advantage over thermosetting matrix composites of being recyclable and of being able to be used or shaped easily. The reinforcement with natural fibers adds an additional advantage to the recyclability resulting from the vegetable origin of the fibers. This is an important element to consider in the ecological context where the aim is to use renewable raw materials that respect the environment. In addition, compared with thermoplastic composites with glass fiber reinforcement, the use of thermoplastic composites with natural fiber reinforcement, in particular based on flax fibers, makes it possible to lighten said composites for equivalent performance. In fact, the density of flax fibers (1.5) is about forty percent lower than that of glass fibers. Hence the growing interest and need to be able to manufacture wicks or ribbons of natural fibers, in particular flax, with consolidation between the fibers of the bundle and improved mechanical strength without twisting. Patent GB 512,558 describes the treatment of cotton fibers with a dispersion of rubber or synthetic resin with a low polymer content ranging from 2 to 10%, without the need to twist the cotton threads for mechanical tensile strength. After impregnation under pressure, the excess dispersion is removed by pressurized air jet, with few polymer particles remaining on the fibers after removing the surplus and drying the fibers. No data on the polymer content remaining between the fibers is specified and no specific example is given on the conditions of production and the precise results obtained. This document also does not describe the specific problem of natural fibers such as flax, as previously discussed, for the purposes of reinforcing thermoplastic matrices of thermoplastic composite materials. On the other hand, patent EP 324 680 describes a device for preparing a reinforced thermoplastic semi-product, such as a material based on polypropylene reinforced with glass fibers. According to this document, the wetting of the reinforcing fibers is even better than the fibers remain in the unitary state and not in the state of wicks or basic son. More particularly, the process described in connection with this device comprises the preparation of an aqueous coating composition comprising a resin in a parcel state and a viscosity regulating agent, and optionally additives, followed by the coating of a facing a mat of reinforcing fibers dispersed in the unitary state with the aqueous coating composition, and then drying to obtain a semi-produced sheet optionally followed by the melting of said resin. No technical problem related to natural fibers such as flax is mentioned in this document which relates more to that of a semifinished product based on a polyolefin reinforced with glass fibers. FR 2 223 173 describes a device for preparing resin-impregnated fiber sheets or ribbons from an aqueous dispersion of resin, in particular thermosetting resin, with dispersion after thickening using a thickening agent. Again the fibers concerned are not natural fibers such as flax and neither the problem nor its solution are suggested.
    [0004] The present invention makes it possible to solve the technical problem described above with respect to the state of the art with a specific device for impregnating wicks or ribbons of natural fibers where this problem arises, this impregnation occurring at heart by a dispersion. A specific aqueous polymer thus allowing said polymer to bind the fibers of said strands or said ribbons to the core of the fiber bundle, ie between them, in order to consolidate them by this specific impregnation with the fine particles of polymer used after fusion. This impregnation can lead further and directly to a pre-impregnated fibrous reinforcement, wick or tape of low grammage usable for the manufacture of composite materials. Thus, the subject of the present invention is a continuous device for impregnating, in a single step, rovings or ribbons of natural fibers, in particular of flax, with a specific aqueous dispersion of polymer in order to consolidate the fibers at the core of the fiber bundle and to improve their mechanical strength without the need for twisting, comprising the following means: stretch stretching means of the wick or ribbon of natural fibers to put them to the desired titration, means for impregnating the fibers with the aid of the aqueous dispersion to guarantee the complete impregnation of the filaments by the latter, means for shaping / calibrating the dewatered fibers, means for drying the shaped / calibrated fibers, and means for conditioning the dried fibers in order to transform them. in wire or ribbon, - said aqueous polymer dispersion comprising at least one amorphous polymer with a Tg of between about 50 ° C and 175 ° C, of reference between about 80 ° C and 150 ° C, or a semi-crystalline polymer with a melting temperature of between about 70 ° and 220 ° C, preferably between about 90 ° C and 190 ° C, more preferably 100 ° C at 170 ° C, said dispersion comprising a content by weight of said polymer of between approximately 5% and 50% with dispersed particles having a number average size of less than 10000 nm, preferably of between approximately 50 and 5000 nm, and more preferably between about 50 and 500 nm. The polymer dispersion according to the invention is a fine dispersion of the polymer particles by limiting the size of said particles so that said particles diffuse easily into the core of the bundle of natural fibers to consolidate (bind together) said fibers. According to preferred embodiments, the device according to the present invention comprises at least one of the following features: the stretch-stretching means comprise a reciprocating translational comb and rotating input and output rollers; output disposed before and after said comb, said rollers creating, rotating in the same direction, a speed differential so that the output speed of the fibers is greater than the input speed of the latter; the stretching elongation means stretch the fibers with an output ratio of between about 1 and 25, preferably between about 3 and 10; the impregnation means consist of a spraying system or a dipping system in an immersion type bath or a contact impregnation roll; the rate of impregnation in the impregnation means is between a few m / min and several tens of m / min, preferably between about 5 m / min and 50 m / min; The impregnation rate of polymer obtained using the impregnation means is between about 0.1% and more than 50% by weight of polymer, preferably between about 2% and 5% for a consolidation effect and between about 35% and 50% for a pre-impregnated product; - The shaping means comprise a dewatering module and a shaping die; - The shaping means exert a spin pressure ranging from a few kg to several hundred kg, preferably about 100 kg; the drying means are chosen from infrared radiation, a microwave flow, an induction heating or an oven with extraction of water, a forced-air oven or hot-roll calendering; the drying temperature is between about 100 ° and 250 ° C, preferably between 100 ° C and 200 ° C; Said polymer is chosen from: (co) polyamides, (co) polyesters, polyurethanes, poly (meth) acrylates, fluorinated polymers or polyolefins. The polymers of said dispersion according to the invention may be homopolymers or copolymers based on at least two monomers or repeating units or they may be polymer mixtures compatible with each other. Compatible polymers means they are miscible with each other, without phase separation; said polymer is chosen from a poly (meth) acrylate, including copolymers, functionalized by acid functional groups or a fluorinated polymer, including copolymers, grafted with reactive functions, said aqueous dispersion is an aqueous dispersion obtained by emulsion polymerization in the presence of a surfactant, and said reactive functions can react with said natural fibers and more particularly with flax fibers. The term acrylic in its general meaning according to the invention, in the absence of specific indication, means both acrylic and / or methacrylic. As an example of an acrylic aqueous dispersion, mention may be made of the dispersion based on a copolymer of methyl methacrylate and of butyl acrylate and acrylic acid. As an example of a fluoropolymer dispersion, aqueous dispersions of PVDF (polyvinylidene fluoride) or copolymers of VDF with other olefins, in particular fluorinated, may be mentioned. The surfactant may be a fluorinated surfactant. As an example of a fluorinated surfactant, mention may be made of the perfluorinated octanoic acid ammonium salt. The grafted fluoropolymer can be obtained by grafting said fluoropolymer with, for example, maleic anhydride; said polymer is a polyurethane formed from a polyisocyanate prepolymer comprising an ionic group, dispersed in water with chain extension in an aqueous medium. In general, such a pre-polymer is obtained by reaction of a diol carrying a carboxylic acid or sulphonic acid function with a polyisocyanate, in particular diisocyanate and optionally another diol without ionic function, in an organic medium, in particular with a solvent easy to remove by evaporation. The dispersion in water is carried out after at least partial neutralization of said acid function, with a mineral base, such as ammonia or an alkali metal hydroxide, or an organic, such as a tertiary amine. The chain extension is carried out with a chain extender carrying functions reactive with the isocyanate functions of said polymer, such as a diamine. The organic solvent base can be removed by evaporation to recover the final aqueous polyurethane dispersion whose dry extract can be adjusted by dilution in water; said polymer is dispersible (or dispersed) in the form of a powder in an aqueous medium without surfactant and preferably said polymer in powder form carries ionic groups or precursor groups of ionic groups, in particular by neutralization in water during the preparation of said dispersion; Said polymer is a copolyamide, preferably carrying carboxyl or sulphonic end groups or amine terminal groups, more preferably having a content of said groups ranging from 50 to 500 peq / g, in particular from 100 to 250 peq / g; Said copolyamide bears amine groups, preferably primary amines, neutralized in the form of ammonium with an acid, preferably Bronsted acid, more preferably phosphorus; said copolyamide carries neutralized carboxy groups, in salt form, with a base; said copolyamide is semi-crystalline with a melting point less than or equal to 150 ° C .; said copolyamide comprises at least one of the following monomers: 5.9, 5.10, 5.12, 5.13, 5.14, 5.16, 5.18, 5.36, 6, 6.9, 6.10, 6.12, 6.13, 6.14, 6.16, 6.18, 6.36, 9, 10.6, 10.9 , 10.10, 10.12, 10.13, 10.14, 10.16, 10.18, 10.36, 11, 12, 12.6, 12.9, 12.10, 12.12, 12.13, 12.14, 12.16, 12.18, 12.36, 6.6 / 6, 11 / 10.10 and their mixtures and preferably comprises at least one of 11, 12, 10.10, 6, 6.10, 6.12, 10.12, 6.14 and / or 6.6 / 6, 11 / 10.10, and mixtures thereof; said polymer is a copolyamide chosen from: PA 6 / 6.6 / 12, PA 6 / 6.6 / 11/12, PA 6/12, PA 6.9 / 12, PA Pip.9 / Pip.12 / 11, PA 6 / IPD .6 / 12, PA IPD.9 / 12, PA6 / MPMD.12 / 12, PA 6 / 6.12 / 12, PA 6 / 6.10 / 12, PA 6 / Pip.12 / 12, PA 6 / 6.6 / 6.10 / 6.1, PA 6.10 / Pip.10 / Pip.12, PA 6/11/12, PA Pip.12 / 12, PA IPD.10 / 12, PA Pip.10 / 12, PA 6/11, PA Pip. 10/11 / Pip.9, PA 6 / 6.6 / 6.10, PA 6 / 6.10 / 6.12 and mixtures thereof; said copolyamide may be semi-aromatic amorphous and chosen from: * 6.1, 8.1, 9.1, 10.I, 11.I, 12.1, 6.1 / 9.1, 9.1 / 10.1, 9.1 / 11.1, 9.1 / 12.1, 9 / 6.1, 10 / 6.1, 11 / 6.1,12: 6.1, 10 / 9.1, 10 / 10.1, 10 / 11.1, 10 / 12.1, 11 / 9.1, 11 / 10.1, 11 / 11.1, 11 / 12.1, 12 / 9.1, 12 / 10.1, 12 / 11.1, 12 / 12.1, 6.10 / 6.1, 6.12 / 6.1, 9.10 / 6.1, 9.12 / 6.1, 10.10 / 6.1, 10.12 / 6.1, 6.10 / 9.1, 6.12 / 9.1, 10.1 / 6.1, 10.10 / 9.1, 10.12 / 9.1, 6.10 / 10.1, 6.12 / 10.1, 9.10 / 10.1, 9.12 / 10.1, 10.10 / 10.1, 10.12 / 10.1, 6.10 / 12.1, 6.12 / 12.1, 9.10 / 12.1, 9.12 / 12.1, 10.10 / 12.1, 11 /6.1/9.1, 11 / 6.1 / 10.1, 11 / 6.1 / 11.1, 11 / 6.1 / 12.1, 11 / 9.1 / 10.1, 11 / 9.1 / 11.1, 11 / 9.1 / 12.1, 11 / 10.1 / 11.1, 11 / 10.1 /12.1, 11 / 11.1 / 12.1, 6.1 / 10.1, 6.1 / 11.1, 6.1 / 12.1, 10.1 / 11.1, 10.1 / 12.1, 11.1 / 12.1, 12 / 6.1 / 10.1, 12 / 6.1 / 11.1, 12 / 6.1 / 12.1, 12 / 9.1 / 10.1, 12 / 9.1 / 11.1, 12.9.1 / 12.1, 12 / 10.1 / 11.1, 12 / 10.112.1, 12 / 11.1 / 12.1, 12 / 11.1 / 12.1, previous terpolymer polyamides with 12 / replaced by 9 /, 10 /, 6.10 /, 6.12 /, 10.6 /, 10.10 /, 10.12 /, 9.10 / and 9.12 /, all polyamid mentioned above, with isophthalic acid (I) partially replaced up to 40 mol% by terephthalic acid (T), 2,6-naphthalene dicarboxylic acid and / or by 1,3- or 1,4-CHDA (acid cyclohexane dicarboxylic), with all or part of the linear aliphatic diamines being able to be replaced by branched aliphatic diamines, preferably from trimethyl hexamethylene diamine TMD, methyl pentamethylene diamine MPMD, methyloctamethylenediamine (MOMD) or cycloaliphatic diamines, preferably from BMACM, BACM and / or IPD or arylaliphatic diamines, preferably m- or p-xylylene diamines all the polyamides mentioned above where the isophthalic (I) is replaced partially or totally by a linear or branched aliphatic diacid C6 to C18 and at the same time with total or partial replacement of the aliphatic diamine with a cycloaliphatic diamine among BMACM, BACM and / or IPD; said polymer is semi-crystalline with a melting temperature Tf greater than 90 ° C., preferably at least 100 ° C., and the particles of said dispersion have a number-average size of between approximately 50 and 5000 nm, and preferably between about 50 and 500 nm. This size of the particles is measured according to laser diffraction method (Coulter LS600) or by scanning electron microscopy. The glass transition temperature Tg of the polymers used is measured using a differential scanning calorimeter (DSC), after a second heat-up, according to the ISO 11357-2 standard. The heating and cooling rate is 20 ° C / min. The melting temperature Tf and the crystallization temperature Tc are measured by DSC, after a first heating, according to the ISO 11357-3 standard. The heating and cooling rate is 20 ° C / min; the dry weight content of said polymer relative to the dry weight of said fibers varies from 0.5% to less than 50%; said weight ratio varies from 0.5 to 10% and said impregnation is limited to the consolidation of said fibers together, in addition to a sizing. In the case of the consolidation of the fibers, their cohesion energy increases because of the connection of said fibers together in the core of the fiber bundle. In the case of a sizing the desired effect is different and related to a compatibilization of said fibers with the polymer matrix of the composite by the interface created around the fibers with a specific polymer improving the compatibility of the fibers with the matrix for better adhesion fibers to the polymer matrix of the composite material; said level is greater than 25% and less than 50%, preferably 30% to 45%, and said impregnation in addition to said consolidation leads to a prepreg of said fibers used or usable separately or successively in the manufacture of composite materials ; the viscosity of said dispersion at 25 ° C. varies from 10 to 1000 MPa.s. The method used for viscosity measurement is the Brookfield method; said fibers are long fibers, in particular long flax fibers, with L / D> 2000; said rovings or ribbons are based on flax fibers having a tex of between about 10 and 10,000, preferably between about 100 and 4000 and more preferably between about 500 and 1500; The invention also relates to impregnated natural fibers, in particular flax fibers, are obtained using the device as described above. Advantageously, the fibers comprise, as consolidation binder at the core of the bundle of said fibers, bonding between said fibers to one another, the semi-crystalline copolyamide as defined above, and preferably at a rate by dry weight of polymer relative to said fibers + polymer ranging from 0.5 to 10%. According to an alternative embodiment, the fibers constitute reinforcing fibers for composites, in particular for thermoplastic composites, preferably for polyamide thermoplastic matrix, more preferably for polyamide matrix based on PA 11, PA10.10 and PA 6.10 and PA 101 The invention also relates to composite materials reinforced by natural fibers obtained using the device as defined above. The invention will now be described in more detail with reference to particular embodiments given by way of illustration only and shown in the accompanying figures in which: - Figure 1 is a perspective view of a device according to the present invention; Figure 2 is a side view of Figure 1; and FIG. 3 is a view from above of FIG. 1. FIGS. 1 to 3 show a device 1 for impregnating natural fibers such as flax with the aid of a specific polymer, in accordance with the present invention. This device 1 comprises, in the direction of displacement F of the fibers 100, stretch-stretching means 10, impregnation means 20, shaping means 30, drying means 40 and conditioning means 50. The stretch-stretching means 10 comprise a pair of rotating input nip rollers 12, a spike-bar comb 14, and a pair of spinning exit nip rolls 16. Fibers 100, for example a strip of combed linen thus continuous in its macroscopic form which is 7 g / m, penetrate the lengthening means 10 by the rotary gripping rollers 25 input and then through the comb 14 which performs a reciprocating translation movement between the two pairs of rotating nip rollers before emerging out of the way after the pair of spinning exit nip rolls 16. The flax fibers are stretched with an elongation ratio of between about 1 30 and 25, preferably between about 3 and 10, for example 7. The elongation of the fibers 100 is produced by both the comb and the rotational speed difference (differential) of the rotating pinch roll pairs, the output rotary nip rollers 16 rotating faster than the input nip rollers 12.
    [0005] Thus, after the first part of the elongation device, the ribbon or wick is 1 g / m, or a draw ratio of 7. The fibers thus stretched then penetrate the impregnation means 20. At this point, the ribbon is very fragile, it then passes through an aqueous dispersion mist that is sent by a spraying system. The impregnation rate is between a few m / min to several tens of m / min, preferably between about 5 m / min and 50 m / min, for example 30 m / min.
    [0006] To carry out the impregnation treatment with an aqueous copolyamide solution, 10 1 of several solutions (aqueous copolyamide dispersions) were made in a laboratory reactor. The copolyamides used are Arkema's commercial products 15 designated respectively Platamid® 2592 and Platamid® 1657. Their essential characteristics are presented in Table I below. Table I Type of Platamid ® Melting temperature COOH functionality (peq / g) 2592 102 ° C 220 1657 107 ° C 180 These products were introduced as a dry powder, in a solution of water with sodium hydroxide (1 % compared to Platamid). The final dry extract (ES) is 30%. The reagents are loaded into a reactor and then the medium is inerted with nitrogen. The reactants are heated for the purpose of reaching the temperature of 150 ° C material. This heating phase is carried out with stirring at 1000 rpm. Between 100 and 120 ° C, the medium becomes homogeneous, white and opaque. The medium is stirred for 30 minutes at 1000 rpm at 150 ° C. and then cooled with stirring at 300 rpm. The dispersions obtained are fluid, white and opaque. The particle size (particle size) of the powders was measured using observations made by Scanning Electron Microscopy and also using the laser diffraction granulometry method. The two types of measurements are concordant. The data shown in the table below were obtained with the laser diffraction granulometry method.
    [0007] The particle size, the viscosity and the solids content of the dispersions used are shown in Table II below. Table II Dispersion Platamid Test Reference Average Diameter Viscosity Brookfield * Particle Dispersion Dry Dry (nm) 23 ° C (MPa $) (%) EP-063 Platamid®2592 80 30 30 EP-064 Platamid®1657 The measurement was made with a No. 1 spindle at 60 rpm.
    [0008] These aqueous dispersions thus prepared are then used in the flax fiber treatment device, in undiluted or diluted form. The impregnation rate of polymer obtained by means of impregnation means is between about 0.1% and more than 50% by weight of polymer, preferably between about 2% and 5% for a consolidation effect and between about 35% and 50% for a pre-impregnated product. In this case, the rate obtained is about 2.5%. After spraying, the impregnated fibers pass through the shaping means 30, which comprises, for example, rubber dewatering rollers 32 between which the fibers are pressed in order to remove the excess of the aqueous polymer dispersion. These two rollers 32 have a first calibration system which forms the intermediate width of the ribbon. The roller means 32 exert a spin pressure ranging from a few kg to several hundred kg, preferably about 100 kg, equivalent to 10 MPa strain on a strip of 6 mm wide and 1 g / m. Then, the fibers thus impregnated pass through a die 34 of calibration or conformation to bring the ribbon obtained to the specific size in thickness and in width, preferably in inches, or 6.35 mm in width, preferably flat but can also be cylindrical. Between each step, there is a pair of treated aluminum roller pair that drives the ribbon so that it is never over a long distance, greater than 1 meter in tension. These ribbon drive rollers, motorized by an electric motor, are controlled by an electromagnetic clutch which adjusts a constant tensile tension of the ribbon. After the calibration step, the ribbon of impregnated fibers 100 is passed through the drying means 40 which evaporate the water contained in the ribbon and thoroughly melt the polymer dispersion to consolidate the ribbon. These drying means 40 comprise, for example, seven short-wave infrared emitters of 1200 Watts and 405 mm in length each, which are connected in series. The power of each emitter may be variable in order to achieve a specific temperature profile for the drying and melting of the polymer. For example, the first three emitters are set at 250 ° C. and then the following four at 180 ° C. The total drying length is about three meters, which corresponds to a drying time of 6 seconds for a tape speed of 30m / min. The drying temperature of the ribbon is between about 100 ° and 250 ° C, preferably between 100 ° C and 200 ° C, for example 150 ° C. The degradation temperature of the flax fibers is about 230 ° C., but the fiber after impregnation, and depending on the length of time it passes through the drying means 40, can accept temperatures between 250 ° C. and 300 ° C. The purpose of the drying is to evaporate the water included in the dispersion and to melt the polymer in the fiber core to obtain a good quality of impregnation. It is necessary that the ribbon at the outlet of the drying means 40 is completely dry at the end of drying and that the thermoplastic polymer has fallen back below its melting temperature, for example less than 110 ° C.
    [0009] At the end of the device, the impregnated, shaped and dried ribbon is wound around a coiler 52 which conditions the product in the form of a spool, for example with a cardboard core of 75 mm internal diameter. The continuous device operates for a constant linear velocity. Tensiometers (not shown) enslave, through the electromagnetic clutch, the ribbon tension so that there is no embrittlement of the fiber until final packaging on the coil. This device thus makes it possible in a single step to lengthen, and without any twisting step, to impregnate, shape, consolidate and condition a very fine linen fiber ribbon of a few g / m, preferably of lg / m, on a reel that can be several thousand meters. The impregnation with a copolyamide dispersion thus makes it possible to very significantly increase the breaking strength of the flax fiber ribbon, while at the same time refining / reducing its linear density. A series of tests was carried out on a roving (wicks of fibers) of linen of high titration or grammage of 2190 tex, with different treatments. Except for Example 7 where the impregnation method is specified, in all other cases (in the absence of particular specification for each example) said impregnation was carried out by in-line (continuous) spraying with the aid of a spray device (spray) with a residence time under the jet of said sprayer of about 1s. The drying is carried out by heating with an infrared device. Cooling is done in the open air. Basis of comparison 1: non impregnated wick of 2190 tex. Example 1: EP-063 ND: impregnation with an undiluted solution (dry extract: 30%) of Platamid®2592. Example 2: EP-063 D50: Impregnation with a 50% diluted dispersion of Platamid® 2592 (dry extract: 15%) Example 3: EP-064 ND: impregnation with an undiluted dispersion of Platamid® 1657 (dry extract: 30%) Example 4: EP-064 D50: impregnation with a diluted 50% dispersion of Platamid® 1657 (Dry Extract: 15%) The second series of tests was carried out on low titration flax roving (1030 tex) ) treated with Platamid ® 1657 at different rates of impregnation. Comparison base 2: non-impregnated low-titre wick (0% of polymer) Example 5: impregnation with diluted solution 3 by a factor of 4 with dry extract: 7.5% Example 6: impregnation 2 times in a row (2 passages Example 7: Immersion impregnation (soaking) in the aqueous dispersion with a longer residence time (10 s) For the tensile strength test, the flax roving is glued on a surface. cardboard frame. The reference length was chosen at 14mm, knowing that the average length of a flax fiber is about 30mm. The upper and lower edges of the carton are clamped between the jaws of the dynamometer (Zwick machine) while the side edges are cut. The roving is then stressed in tension at a speed of 1 mm / min. In order to compare the rovings weakly impregnated with resin (up to 10% of polymer), the breaking force of the different samples tested is measured. The results are shown in Table III below. Table III Reference Base of Example 1 Example 2 Example 3 Example Comparison 1 4 Type Non-impregnated EP63-ND EP63-D50 EP64-ND EP64-D50 Impregnation Resin content by weight 0 2-10% 2-10% 2-10 % 2-10% Number 5 8 5 5 5 of samples Average strength 443 775 723 888 770 at break (N) Standard deviation 33 98 68 23 73 It is shown in Table III that the impregnation with a copolyamide dispersion significantly increases the breaking strength of the flax fiber wick. The two dispersions give similar results and in the sense of a consolidation (examples 2 and 3 as opposed to comparison base 1), which demonstrates that the proposed consolidation dispersion works, including for 50% dilutions ( which corresponds to a solids content of 15%). In Table IV below, the result of the different impregnations is given with Platamid ® 1657 and a wick of low grammage or titration (1030 tex). It can be seen that, with a dilution of a factor 4 with a final solids content of 7.5%, a breaking force equivalent to that obtained with the non-impregnated high titration roving (2190 tex) is obtained (comparison of the example 5 with the basis of comparison 1). It has thus been demonstrated that the use of a copolyamide dispersion as defined above has made it possible to use a tow of titanium fiber fiber divided by 2 with respect to the initial wick (1030 tex versus 2190 tex), all retaining substantially the same mechanical strength (about same breaking strength). It is further shown that by making several impregnation passes (by spraying) with the same dispersion, the level of copolyamide in the final wick is increased (comparison between Examples 5 and 6).
    [0010] Finally, it is shown by an immersion impregnation test (soaking) with a much longer spray time (10s), that it is possible to impregnate the wick with almost 40% (by weight) of copolyamide ( Example 7). This rate corresponds to a resin content (polymer) encountered in conventional pre-impregnated reinforcements, making it possible to make composite parts directly, for example by thermo-compression, or else using a fiber placement technology such as pultrusion, without having recourse to an additional impregnation operation of the fibrous reinforcement.
    [0011] Thus, the possibility with the device according to the invention of directly producing a ready-to-use pre-impregnated composite semi-product is demonstrated.
    [0012] Table IV Reference Base of Example 5 Example 6 Example 7 Comparison 2 Type No Diluted Product of Impregnated Impregnation Impregnated Factor 4 Impregnation Immersion of 10s (ES: Factor 4 7.5%) (ES: 7 , 5%) with 2 passes Rate of 0 2.7 5.3 39.8 polymer (% wt / fiber + polymer) Number 5 5 5 3 samples Average strength 202 449 549 948 at break (N) Standard deviation The present invention thus makes it possible to solve the technical problems described above with respect to the prior art with a device for impregnating wicks or ribbons of natural fibers, this impregnation taking place at heart by an aqueous polymer dispersion. Specifically allowing said polymer to bind to the core of the fiber bundle, between them, the fibers of said locks or ribbons to consolidate with the fine polymer particles used after melting.
    [0013] This impregnation can lead later to a pre-impregnated fibrous reinforcement, a wick or a light weight ribbon usable for the manufacture of composite materials.
    [0014] The flexibility of the solution of the present invention allows it to be integrated into a continuous line of manufacture of said fiber reinforcement based on natural fibers such as flax fibers, ranging from the treatment of natural fibers from the fields, to the manufacture of a pre-impregnated and calibrated wick or ribbon. Thus, in a single step, a wick or ribbon is obtained which contains the flax fiber and the resin at a level which may be between 0 and 70% by weight of resin. It does not require a cutting step to calibrate the width of the product because the shaper system ensures this step It goes without saying that the detailed description of the subject of the invention, given solely by way of illustration, does not constitute in no way a limitation, the technical equivalents also being within the scope of the present invention.
    [0015] Thus, the impregnating means 20 may comprise dipping system in an immersion type bath or a contact impregnation roll. The drying means 40 may also be constituted by a microwave flow, an induction heating or an oven with extraction of water, a forced air oven or a hot roll calendering. These drying means may include radiation funneling systems for concentrating energy to the product to be dried.
    权利要求:
    Claims (31)
    [0001]
    REVENDICATIONS1. Continuous device (1) for impregnating in a single step strands or ribbons of natural fibers (100), in particular flax, with a specific aqueous dispersion of polymer for consolidating the fibers in the core of the fiber bundle and improving their mechanical strength without the need for twisting, comprising the following means: stretching means (10) for stretching the wick or ribbon of natural fibers in order to obtain the desired titration, means for impregnating the fibers with using the aqueous dispersion to guarantee the complete impregnation of the filaments by the latter, - means (30) for shaping / calibrating the dewatered fibers, - means (40) for drying the shaped / calibrated fibers, and - means (50) for conditioning the dried fibers to turn them into yarn or tape, said aqueous polymer dispersion comprising at least one amorphous polymer with a Tg of from about 50 ° C to 175 ° C; between about 80 ° C and 150 ° C, or a semi-crystalline polymer with a melting temperature between about 70 ° and 220 ° C, preferably between about 90 ° C and 190 ° C, more preferably 100 ° C. C at 170 ° C, said dispersion comprising a content by weight of said and 50% with particles in number average of between about 50 and 5000 nm, polymer between about 5% dispersion having a size of 10000 nm, preferably included and more preferably between about 50 and 500 nm.
    [0002]
    2. Device according to claim 1, characterized in that the elongation means (10) comprise a reciprocating reciprocating blade (14) and rotary inlet (12) and outlet (16) rollers arranged before and after said comb, said rollers creating, rotating in the same direction, a speed differential such that the output speed of the fibers is greater than the input speed of the latter.
    [0003]
    3. Device according to claim 1 or 2, characterized in that the elongation means (10) stretch the fibers (100) with an output ratio of between about 1 and 25, preferably between about 3 and 10.
    [0004]
    4. Device according to any one of the preceding claims, characterized in that the impregnation means (20) are constituted by a spraying system or a dipping system in an immersion type bath or an impregnation roll. contact.
    [0005]
    5. Device according to claim 4, characterized in that the rate of impregnation in the impregnation means (20) is between a few m / min to several tens of m / min, preferably between about 5 m / min and 50 m / min.
    [0006]
    6. Device according to any one of the preceding claims, characterized in that the polymer impregnation rate obtained using the impregnation means (20) is between about 0.1% to more than 50% by weight. polymer mass, preferably between about 2% and 5% for a consolidation effect and between about 35% and 50% for a pre-impregnated product.
    [0007]
    7. Device according to any one of the preceding claims, characterized in that the shaping means (30) 25 comprise a dewatering module (32) and a shaping die (34).
    [0008]
    8. Device according to claim 7, characterized in that the shaping means (30) exert a dewatering pressure ranging from a few kg to several hundred kg, preferably about 100 kg.
    [0009]
    9. Device according to any one of the preceding claims, characterized in that the drying means (40) are selected from infrared radiation, a microwave flow, induction heating or oven with water extraction , a forced air oven or hot roll calendaring.
    [0010]
    10. Device according to claim 9, characterized in that the drying temperature is between about 100 ° and 250 ° C, preferably between 100 ° C and 200 ° C.
    [0011]
    11. Device according to any one of the preceding claims, characterized in that said polymer is chosen from: (co) polyamides, (co) polyesters, polyurethanes, poly (meth) acrylates, fluorinated polymers or polyolefins.
    [0012]
    12. Device according to claim 11, characterized in that: - said polymer is chosen from a poly (meth) acrylate, including copolymers, functionalized with acid functional groups or a fluorinated polymer, including copolymers, grafted with reactive functions. said aqueous dispersion is an aqueous dispersion obtained by emulsion polymerization in the presence of a surfactant, and said reactive functions can react with said natural fibers and more particularly with flax fibers.
    [0013]
    13. Device according to claim 11, characterized in that said polymer is a polyurethane formed from a polyisocyanate prepolymer comprising an ionic group, dispersed in water with chain extension in an aqueous medium.
    [0014]
    14. Device according to any one of claims 1 to 11, characterized in that said polymer is dispersible (or dispersed) in powder form in an aqueous medium without surfactant and preferably said polymer in the form of powder carries groupings ionic groups or precursor groups of ionic groups, in particular by neutralization in water during the preparation of said dispersion.
    [0015]
    15. The device as claimed in claim 14, characterized in that said polymer is a copolyamide, preferably carrying carboxyl or sulphonic end groups or amine end groups, more preferably having a content of said groups ranging from 50 to 500 g / g, in particular 100 to 250 μeq / g
    [0016]
    16. Device according to claim 15, characterized in that said copolyamide carries amine groups, preferably aminesprimaires, neutralized in ammonium form by an acid, preferably Bronsted acid, more preferably phosphorus.
    [0017]
    17. Device according to claim 15, characterized in that said copolyamide carries neutralized carboxy groups, in the form of salt, with a base.
    [0018]
    18. Device according to any one of claims 15 to 17, characterized in that said copolyamide is semi-crystalline with a melting temperature less than or equal to 150 ° C.
    [0019]
    19. Device according to any one of claims 15 to 18, characterized in that said copolyamide comprises at least one of the following monomers: 5.9, 5.10, 5.12, 5.13, 5.14, 5.16, 5.18, 5.36, 6, 6.9, 6.10 , 6.12, 6.13, 6.14, 6.16, 6.18, 6.36, 9, 10.6, 10.9, 10.10, 10.12, 10.13, 10.14, 10.16, 10.18, 10.36, 11, 12, 12.6, 12.9, 12.10, 12.12, 12.13, 12.14, 12.16 , 12.18, 12.36, 6.6 / 6, 11 / 10.10 and mixtures thereof and preferably comprises at least one of 11, 12, 10.10, 6, 6.10, 6.12, 10.12, 6.14 and / or 6.6 / 6, 11 / 10.10 , and their mixtures.
    [0020]
    20. Device according to any one of claims 15 to 18, characterized in that said polymer is a copolyamide chosen from: PA 6 / 6.6 / 12, PA 6 / 6.6 / 11/12, PA 6/12, PA 6.9 / 12, PA Pip.9 / Pip.12 / 11, PA 6 / 1PD.6 / 12, PA IPD.9 / 12, PA6 / MPMD.12 / 12, PA 6 / 6.12 / 12, PA 6 / 6.10 / 12, PA 6 / Pip.12 / 12, PA 6 / 6.6 / 6.10 / 6.1, PA 6.10 / Pip.10 / Pip.12, PA 6/11/12, PA Pip.12 / 12, PA IPD.10 / 12, PA Pip.10 / 12, PA 6/11, PA Pip.10 / 11 / Pip.9, PA 6 / 6.6 / 6.10, PA 6 / 6.10 / 6.12 and mixtures thereof.
    [0021]
    21. Device according to any one of the preceding claims, characterized in that: - said polymer is semi-crystalline with a melting temperature Tf greater than 90 ° C, preferably at least 100 ° C, and 30 - the particles of said dispersion have a number average size of between about 50 and 5000 nm, and preferably between about 50 and 500 nm.
    [0022]
    22. Device according to any one of the preceding claims, characterized in that the dry weight ratio of said polymer relative to the dry weight of said fibers varies from 0.5% to less than 50%.
    [0023]
    23. Device according to claim 22, characterized in that said weight ratio varies from 0.5 to 10% and said impregnation is limited to the consolidation of said fibers together, in addition to a sizing.
    [0024]
    24. Device according to claim 22, characterized in that said rate is greater than 25% and less than 50%, preferably 30% to 45%, and said impregnation in addition to said consolidation leads to a prepreg of said fibers used. or usable separately or successively in the manufacture of composite materials.
    [0025]
    25. Device according to any one of the preceding claims, characterized in that the viscosity of said dispersion at 25 ° C varies from 10 to 1000 MPa.s.
    [0026]
    26. Device according to any one of the preceding claims, characterized in that said fibers are long fibers, in particular long flax fibers, with L / D> 2000.
    [0027]
    27. Device according to any one of the preceding claims, characterized in that said locks or ribbons are based on flax fibers having a tex between about 10 and 10,000, preferably between about 100 and 4000 and more preferably between about 500 and 1500.
    [0028]
    28. Natural fibers impregnated, in particular flax fibers, characterized in that they are obtained using the continuous impregnation device according to one of claims 1 to 27. 25
    [0029]
    29. Fibers according to claim 28, characterized in that they comprise as binding binder at the core of the bundle of said fibers, binder between said fibers together, the semi-crystalline copolyamide as defined in one of claims 8 to 14, and preferably at a dry weight ratio of polymer to said polymer fibers ranging from 0.5 to 10%.
    [0030]
    30. Fibers according to claim 28 or 29, characterized in that they constitute reinforcing fibers for composites, in particular for thermoplastic composites, preferably for polyamide thermoplastic matrix, more preferably for polyamide matrix based on PA 11, PA10. .10 and PA 6.10 and PA 101/61.
    [0031]
    31. Composite materials reinforced with natural fibers, characterized in that they comprise fibers obtained using the device according to one of claims 1 to 27, or fibers as defined according to any one of claims 28 at 30.
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    同族专利:
    公开号 | 公开日
    CN106488836A|2017-03-08|
    EP3142840A1|2017-03-22|
    KR20170104369A|2017-09-15|
    JP2017521565A|2017-08-03|
    FR3020776B1|2016-05-27|
    JP6625063B2|2019-12-25|
    US20170246766A1|2017-08-31|
    US10513054B2|2019-12-24|
    WO2015173489A1|2015-11-19|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1454199A|FR3020776B1|2014-05-12|2014-05-12|CONTINUOUS DEVICE FOR IMPREGNATING ONLY ONE STEP NATURAL FIBERS OR RIBBONS, IN PARTICULAR LIN|FR1454199A| FR3020776B1|2014-05-12|2014-05-12|CONTINUOUS DEVICE FOR IMPREGNATING ONLY ONE STEP NATURAL FIBERS OR RIBBONS, IN PARTICULAR LIN|
    US15/310,284| US10513054B2|2014-05-12|2015-05-04|Continuous device for impregnating, in a single step, strands or ribbons of natural fibers, in particular of linen|
    EP15728047.0A| EP3142840A1|2014-05-12|2015-05-04|Continuous device for impregnating, in a single step, strands or ribbons of natural fibres, in particular linen|
    JP2016567547A| JP6625063B2|2014-05-12|2015-05-04|Continuous device for impregnating natural fibers, especially linen yarns or ribbons, in a single stage|
    KR1020167034738A| KR20170104369A|2014-05-12|2015-05-04|Continuous device for impregnating, in a single step, strands or ribbons of natural fibres, in particular linen|
    PCT/FR2015/051179| WO2015173489A1|2014-05-12|2015-05-04|Continuous device for impregnating, in a single step, strands or ribbons of natural fibres, in particular linen|
    CN201580037819.8A| CN106488836A|2014-05-12|2015-05-04|For impregnating the cotton rope of natural fiber especially Caulis et Folium Lini or the continuous apparatus of band in a single step|
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