EP3015581A1 - Fabric with shape memory and method for manufacturing same as well as preferred uses - Google Patents

Abstract

The knitted textile structure is made by chain mesh or Rachel technology comprising threads or strips made of shape memory material (103, 104), inserted in the production sense, bonded to each other by knitting by means of textile threads of different nature ( 101), said son made of shape memory material remaining substantially rectilinear within the structure.

Description

FIELD OF THE INVENTION

The invention relates to the field of "smart" textiles. More specifically, it relates to shape memory textiles, that is to say, consisting of a structure made of an adaptable flexible material that can change its shape reversibly in response to a stress on the environment. The nature of this solicitation can be of various nature: thermal, mechanical, electrical, energetic ..... The return to the original state can be obtained spontaneously by loosening the previous constraint or in a way assisted by an action external thermal or mechanical nature.

This textile is a hybrid composed of son or strips of shape memory, arranged rectilinearly in the cross direction and / or production sense, connected by other textile son shape memory or not.

The invention is intended to be implemented in particular in the following areas: medical (prostheses, ...), building, automotive, but also domestic or industrial casts.

It is intended to obtain a variation of form in the steps of use of the product as a function of the temperature or of the mechanical stresses to which it is subjected according to the martensitic or austenitic states of the shape memory material. The shape variations result from the super elastic properties, also referred to as pseudoelastics in the literature, of the single or double temperature effect shape memory material or effect.

The invention also relates to a method for producing such a textile. It relies mainly on the use of the modification of the physical state of the shape memory material by joule effect during each cycle of reversal of the frame.

PRIOR STATE OF THE TECHNIQUE

The shape memory materials are known to date in military and aeronautical applications, but especially in medical applications, in particular for the development of cardiac stents.

The document FR 2,712,177 discloses a prosthetic element consisting of a fabric resulting from the weaving or knitting of multistrand polyester son forming an airy structure with square or rectangular mesh, the polyester son can be combined with metal son with or without a memory.

The uses for optical applications in spectacle frames are also known.

Shape memory alloys are alloys that have the ability to "keep in memory" an initial shape and to return to it even after deformation. They thus have the possibility of alternating between two forms previously stored when the temperature varies around a critical temperature. They also exhibit a super elastic behavior allowing elongations without permanent deformation, higher than those of other metals.

Among the major shape memory alloys, a variety of alloys of nickel and titanium are found as major constituents in almost equal proportions. Nitinol generically refers to all these alloys.

In the textile field, the use of such materials has been proposed, for example in the document EP 2 028 309 . This document describes a textile structure made on a hook loom comprising integrated partial-raster shape memory son, with a view to the production of vibration absorption systems in composite materials, and in particular for the production of helmets. protection.

These textiles incorporating shape memory wires have relatively complex weaves, implying for the son in question significant radii of curvature. Such radii of curvature limit the diameter of the usable wire (about 100 or 200 micrometers maximum). These armors also make the use of the shape memory characteristic complex since the threads are subjected to tortuous pathways and therefore to numerous mechanical stresses that do not make it possible to predict the shape obtained after crossing the threads on the textile loom.

Moreover, a subsequent training in shape, that is to say after completion of the textile is not possible because of the temperature required for such training (250 to 500 ° C), incompatible with the melting temperature of the most textile fibers.

SUMMARY OF THE INVENTION

The invention relates to a knitted textile structure in chain mesh or Rachel technology comprising son or strips made of shape memory material, inserted in the production sense and possibly also in cross-machine directions, and linked together by knitting by means of textile threads of different nature.

In the textile weave, the shape memory wires retain a layout very close to a straight chain situation, or even a frame. This arrangement is obtained by the use of a framer and chain pass directly without mesh son. Both directions can be used simultaneously.

Thus, son or strips made of shape memory material can be inserted in the production direction. They remain substantially rectilinear within said structure and are related to the structure. By preserving a substantially rectilinear direction of the son or strips of shape memory material, one respects the metallurgical state of said material, and corollary, its sought characteristics of shape memory.

The direct passage of shape memory wires, for example at the unwinding, and not scrolling, greatly reduces the mechanical stresses to which they are subjected, and thus allows to retain the shape memory characteristics previously given audits son.

The shape-memory wires may be made of a metal alloy of the nitinol (nickel-titanium alloy) or Cu-Ni type, for example, or composed of specific polymers incorporating carbon nanotubes, for example, capable of conferring on them shape memory.

They consist of actual son, diameter between 50 micrometers and 5 millimeters, or strips, whose width is between 50 micrometers and 5 millimeters, and whose thickness is between 50 and 600 micrometers.

The son of connection between the rectilinear son are of textile nature. By way of example, mention may be made of polyester, polyamide, polyethylene, polypropylene, or even glass, basalt, wire and even finer shape memory wires than the main wires inserted into chain and / or weft (typically 30 to 80 micrometers in diameter).

In addition, the live passage allows the use of relatively rigid shape memory wires, typically nitinol alloys of 100 micrometers to 5 millimeters in diameter or more, unusable under other conditions precisely because of such a diameter .
The use of mineral or metal threads also allows training in shape possibly subsequent to the development of the textile since these fibers withstand the very high temperatures required for this learning (150 to 500 ° C).

• soit de retrouver une forme après mise en place, par effet de super élasticité, c'est-à-dire capacité à retrouver une forme initiale après déformation importante dans la phase de mise en place ;
• soit de retrouver une forme sous l'effet de la température d'utilisation ;
• soit à adopter des formes différentes dans les différentes phases d'exploitation du textile, tel que par exemple pour un store de voiture ou de bâtiment

The present invention makes it possible to obtain a textile structure capable of:

• or to find a shape after installation, by superelasticity effect, that is to say, ability to recover an initial shape after significant deformation in the implementation phase;
• to find a shape under the effect of the temperature of use;
• to adopt different forms in the various phases of textile operation, such as for example for a car or building awning

Thus, in the first case (superelasticity), the invention is capable of being implemented in a medical application of parietal implants, and generally of medical or surgical implants. The implant can be folded on itself or compressed to be introduced by a reduced orifice (laparoscopy) performed by the surgeon and found its shape in the abdominal cavity. The same property of super elasticity can be used for other domestic or industrial uses.

In the second case (temperature-dependent single sense memory effect), the invention may for example also be implemented in medical uses. The textile structure constituting an implant finds a particular shape at the temperature of the human body. In industrial applications, the invention is used in a given temperature range corresponding to the martensitic phase of the wire.

In the third case, the invention finds application in the building or automobile, especially for the realization of a blind. This is wound and stored on a rectilinear support (shaft), and when unfolded, it adopts a curved shape or other predetermined shape matching the shape of the glazing, because of the shape memory that has been conferred. This curved shape results from a return to the martensitic state or the use of the superelasticity which gives the structure a certain rigidity. The curved shape is then obtained either by shaping or simply by the mechanical pressure exerted on the edges of the fabric or complex.

In addition, according to the invention, the textile structure obtained can undergo after its development a double-acting form of learning to give it two different forms at different temperatures, typically between 40 and 100 ° C and between 120 and 260 ° C. In doing so, it is likely to be implemented for the production of pastry molds or industrial molds.
Thus, in the context of a pastry mold, it can close for cooking, under the effect of temperature and opens during cooling. The opposite effect can obviously be obtained during freezing or freezing phases.

According to one variant, the armor used for the binding yarns may be of a different type, single or double knit, two or three bars, the binding yarns working in a single-needle chain, and in two-needle knuckles. The shape memory wires are introduced in weft on all or part of the textile.

Other more or less closed armor can be implemented with a high density of textile son, giving a closed structure or more open structures with textile son diagonal crossing.

According to another embodiment of the invention, the textile structure may also include direction-oriented shape memory son integrated in direct passage, sometimes called capstan in one of the previously described armor. In this case said son can be integrated on creel or beam at the unrolled to respect the shape memory possibly already given.

The knitted fabric structure of the invention may also comprise zones provided with weft-shaped and possibly capstan-shaped shape memory wires and other zones that are free of these weft or capstan threads by virtue of a particular threading or by the use of a programmable electronic framer.

The same process can be implemented on a multiaxial machine to obtain an orientation of the shape memory wires at an angle of 20 to 80 ° with respect to the main direction of production.

According to the invention, the binding yarn is chosen from the non-limiting group comprising the monofilament or multifilament type of polyester, polyamide, polyethylene, polypropylene or metal or even glass or any other mineral material (basalt for example) capable of withstanding the possibly high temperatures (250-500 ° C) of shape learning of shape memory materials.

The invention also relates to the method of producing such a structure. This method uses jet mesh technology with framer or Rachel multi-axial technology.

According to this method, it is possible to apply to the son or strips of shape memory, especially when they are too rigid to allow them to be printed at an angle close to 180 ° during the return of screening, an electric voltage during the reversal of the framer, causing a local heating only between two electrodes and integrated on the overturning puncture or the passer of the framer. This heating is very important and makes the shape memory wire lose its rigidity and possibly locally its shape memory, thus conferring great ease of deformation of the material. This heating is advantageously carried out over an area varying from approximately 0.15 to 5 cm with the aid of a double electrode on or near the overturning piqueur or the passer of the framer to obtain a deformation of the wire during the heating phase. turnaround.

In the context of the invention, it is also possible to associate a "fleeze" or sail with the structure thus produced. This "fleeze" or veil can be a non-woven fabric, a woven fabric, a mesh fabric or a plastic film. This "fleeze" associated can provide a technical function, for example filtration, insect protection or separation media in a medical or industrial application for example. The shape memory wires or strips then make it possible to maintain the structure in place or in shape. It can also be envisaged that the activation of the shape memory by passing to the austenitic state ensures a particular function (cleaning of a filter for example).

As already mentioned, the method of the invention can provide training of shape of the structure after its development, and especially at high temperature, typically between 150 and 500 ° C, because of the nature of the bonding son then used (metal, glass, basalt).

In a variant, the method of embodiment of the invention uses a double needle loom. At least one of the two needle beds has the characteristics described by integrating the shape memory wires according to the previous descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

• La figure 1 est une représentation schématique d'une structure textile tricotée obtenue sur un métier de type Rachel trameur.
• La figure 2 est une représentation schématique d'une structure analogue à celle de la figure 1, mais avec insertion de fils à mémoire de forme à la fois en chaîne et en trame.
• Les figures 3a et 3b illustrent une utilisation médicale de la structure textile de l'invention, respectivement en position repliée et dépliée.
• Les figures 4a à 4c illustrent schématiquement l'utilisation de la structure textile de l'invention pour la réalisation d'un store pour toit panoramique d'un véhicule automobile.
• La figure 5 est une illustration schématique du procédé de l'invention qui peut être appliqué pour permettre le retournement de trame par échauffement électrique.
• La figure 6 est une représentation schématique d'une structure textile tricotée conforme à l'invention, mettant en oeuvre une autre armure.

The manner in which the invention can be realized and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, given as an indication and not a limitation to the accompanying figures.

• The figure 1 is a schematic representation of a knitted textile structure obtained on a loom type Rachel framer.
• The figure 2 is a schematic representation of a structure similar to that of the figure 1 but with insertion of shape memory wires in both warp and weft.
• The Figures 3a and 3b illustrate a medical use of the textile structure of the invention, respectively in the folded and unfolded position.
• The Figures 4a to 4c schematically illustrate the use of the textile structure of the invention for producing a blind for a panoramic roof of a motor vehicle.
• The figure 5 is a schematic illustration of the method of the invention that can be applied to allow the reversal of the frame by electric heating.
• The figure 6 is a schematic representation of a knitted fabric structure according to the invention, implementing another armor.

DETAILED DESCRIPTION OF THE INVENTION

So we illustrated in relation to the figure 1 the textile structure, as obtained with Rachel technology, such as for example with a Karl Mayer or Liba type of craft. One could still implement Comez hook technology, or a technology business chain.

In this case, it is a structure of connecting son 101 charming type, knit, incorporating son 103 made of shape memory material, and typically nitinol, inserted in weft or cross-machine direction.

The connecting son 101 are of traditional manufacture, and for example, made of polyester.

However, it is possible to choose, for these connection wires, materials that are resistant to the training temperature of the shape memory material of the wires 103. For example, they may be of a mineral (glass or basalt) or metallic (stainless steel) nature. , nickel, ...), and in this case, sustain greater subsequent processing temperatures, while allowing the textile structure obtained by conventional track is trained to form the shape of conventional learning temperatures son 103 entering in his constitution.

The figure 2 illustrates a variant of the invention, wherein the shape memory son 103 and 104 are oriented in the warp and weft directions.

We have shown in relation with the Figures 3a and 3b an example of application of the textile structure of the invention as an implant. The figure 3a shows the implant in "folded" situation, suitable to allow its placement or insertion in a location determined by the practitioner.

The figure 3b shows the implant in place in the human body, said implant having recovered a predefined shape, in the planar species, under the effect of the temperature of the human body, and by the implementation of shape memory wires 303 and 303, oriented in the example described in the warp and weft directions.

We have shown in relation with the Figures 4a to 4c another application of the textile structure of the invention, namely, the realization of a blind for occulting on demand, a panoramic roof, for example of a motor vehicle.

The figure 4a is a section of the roof 405 of the car, on which we can observe the shade 406 blackout or translucent in position. This blind can be stored on a straight shaft 407, arranged for example vertically above the rear window of said vehicle (see figure 4c ).

The figure 4b shows the principle of operation of the awning. The latter, when unrolled from the storage shaft 407, adopts a curved shape substantially parallel to the roof of said vehicle, due to the use of shape memory wires 403, which, because of the characteristics of super elasticity they develop, induce the return of the blind to a previously determined form. This curved shape may also result from the inherent rigidity of the shape memory wires, so that because of the presence of slide 408, formed on either side of the roof, the blind adopts such a shape.

The figure 5 is a scheme of the framer of a machine type Rachel or hook incorporating a device for local electrical tensioning of the weft yarn.

The bonding yarn structure 501 schematized here by parallel fine lines may be full or openwork weave. It incorporates in the form of shape memory wires of metal type 502. The wire is distributed by the slider in alternative translation provided with a passette 504 for the passage of the wire 502.

The stitches of the framer 503 hold the wire and fold it by a movement of up and down at the time of the formation of the mesh to integrate the frame.

At the moment perfectly adapted in the cycle of setting up the weft and for a very precise duration related to the resistance of the wire and to the speed of the machine, a voltage is applied between the electrodes 505 and 506 or 505 and 507 to allow local deformation of the shape memory wire as a result of the locally generated Joule effect.

This deformation makes it possible to carry out the weft return of the shape memory wire beyond a diameter of approximately 200 μm, impossible without this device, and by acting on the superelasticity of the shape memory material.

We have represented in the figure 6 an embodiment of the invention. It aims in particular to illustrate the rectilinear orientation of the son or shape memory strips 603 within the knit thus defined, and in the objective, as mentioned above, to respect the metallurgical state of the material constituting them, and corollary , of its sought-after properties of memory of form.

In this structure, the gill strands 601 and 602 form a net, while the shape memory wires 603 pass from one chain to the other by slight translation of the guide bar of these son.

The shape memory wires 603 are therefore integrated into this structure at the unwinding, since they emanate from a wire donor, so that it avoids friction and heating that may modify them.

This type of structure is perfectly deformable as can be a net at room temperature, if said temperature corresponds to the martensitic state of the constituent material of the shape memory wires 603. When the temperature is raised, to reach the austenitic state of said material, due to the shape memory effect imparted to said son, the net tends to close, said son becoming rectilinear due to the rise in temperature. If, however, the temperature corresponds to the austenitic state of the material, the superelasticity effect tends to keep the net closed, and tends in any case to oppose its opening.

Claims (14)

Knitted textile structure made by chain or Rachel mesh technology comprising threads or strips made of shape memory material (103, 104, 303, 304, 403, 603), characterized : In that the son or strips made of shape memory material are inserted in the production direction, And in that the threads or strips are bonded to one another by knitting with different types of textile threads (101, 601, 602), and in that said threads or strips made of shape-memory material remain substantially rectilinear within the structure. Knitted textile structure according to claim 1, characterized in that threads or strips (104, 304, 603) made of shape memory material are further inserted transversely, in that they remain substantially rectilinear within said structure and in that they are linked to the structure. Knitted textile structure according to one of claims 1 and 2, characterized in that the diameter of the son made of shape memory material is between 50 micrometers and 5 millimeters. Knitted textile structure according to one of claims 1 and 2, characterized in that the width of the strips (103, 104, 303, 304, 403, 603) made of shape memory material is between 50 micrometers and 5 millimeters, and in that their thickness is between 50 and 600 micrometers. Knitted textile structure according to one of claims 1 to 4, characterized in that the binding yarns (101, 601, 602) are mono- or multi-filament yarns, and are made of a material selected from the group consisting of polyester , polyamide, polyethylene, polypropylene, metals or a mineral fiber of glass or basalt type. Process for the production of a knitted textile structure according to one of Claims 1 to 5, characterized in that it uses jet mesh technology with a framer or Rachel multiaxial technology. Process for the production of a knitted textile structure according to claim 6, characterized in that a "fleeze" or sail is associated with the structure, said "fleeze" or veil being made of a nonwoven, a woven, a mesh fabric or plastic film. Process for the production of a knitted textile structure according to one of Claims 6 and 7, characterized in that the warp yarns and the shape memory weft yarns (104, 304, 603) are heated in the back of framing, by localized application of an electric voltage able to induce by Joule effect a local heating of said wire. Process for the production of a knitted textile structure according to claim 8, characterized in that the application of the electrical voltage is carried out by means of two electrodes integrated on the reversing piqueur or in the passoir of the framer of the trade chain or Rachel . Process for the production of a knitted textile structure according to claim 9, characterized in that the spacing of the two electrodes at their zone of cooperation with the shape memory wire is between 0.15 and 5 cm. Process for the production of a knitted textile structure according to one of Claims 6 and 7, characterized in that the textile structure obtained undergoes a shape formation at high temperature between 150 and 500 ° C. after its production. Process for the production of a knitted textile structure according to one of Claims 1 to 5, characterized in that it uses a double needle bed, one of the two needle beds at least incorporating shape memory wires. according to one of the features described. Process for the production of a knitted textile structure according to one of Claims 1 to 5, characterized in that the textile structure obtained undergoes, after its production, a double-effect shape learning in order to give it two different shapes at different temperatures. typically between 40 and 100 ° C and between 120 and 260 ° C. Use of the knitted textile structure according to one of claims 1 to 5 for the production of products selected from the group comprising medical or surgical implants, blinds for automobiles or for habitation, molds, especially pastry or industrial.

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