FR2959247A1 - SHAPE MEMORY TEXTILE AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

The knitted textile structure is made by chain or Rachel mesh technology comprising threads or strips made of shape memory material (103, 104) inserted in cross-direction, bonded together 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 so-called "intelligent" 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, energy 10 The return to the original state can be obtained spontaneously by loosening the previous stress or assisted by an external action of a thermal nature or mechanical.

This textile is a hybrid composed of son or strips of shape memory, arranged rectilinearly in 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, automobile, but also domestic or industrial 20 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 is mainly based 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.

STATE OF THE PRIOR ART Memory shape materials are known today in military and aeronautical applications, but especially in medical applications, in particular for the development of cardiac stents.

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 superior to 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 having partial-section integrated shape memory wires, view of the realization of vibration absorption systems in composite materials, and in particular for the production of protective helmets.

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.

Furthermore, subsequent training in shape, that is to say after completion of the textile 30 is not possible because of the temperature required for such training (250 to 500 ° C), incompatible with the melting temperature of most textile fibers.

SUMMARY OF THE INVENTION

The invention relates to a textile knitted fabric structure chain or Rachel mesh comprising son or strips made of shape memory material, inserted in cross-machine direction and possibly also in production sense, and linked together by knitting by means of son textiles of different nature. In the textile armor, the shape memory wires retain a layout very close to a rectilinear situation in frame or even in a chain. 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.

The direct passage of the shape memory wires greatly reduces the mechanical stresses to which they are subjected, and thus makes it possible to retain the shape memory characteristics previously given to the 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 properties of shape memory.

They consist of yarns proper, of 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 inserted main wires. chain and / or weft (typically 30 to 80 micrometers in diameter).

In addition, the direct 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 because of precisely such diameter.

The use of mineral or metal threads also allows shape learning 35 possibly after the development of the textile since these fibers withstand the very high temperatures required for this learning (150 to 500 ° C).

The present invention makes it possible to obtain a textile structure capable of: either recovering a shape after placement, by superelasticity effect, that is to say, ability to recover an initial shape after significant deformation in the setting phase. square ; 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 a framer or Rachel multiaxial 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.

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 incorporating the shape memory wires according to the previous descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS The manner in which the invention may be implemented and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, given for information and nonlimitingly with the aid of the appended figures.

Figure 1 is a schematic representation of a knitted fabric structure according to a first embodiment of the invention obtained on a loom type Rachel framer. FIG. 2 is a schematic representation of a structure similar to that of FIG. 1 but with insertion of both warp and weft shape memory wires. Figures 3a and 3b illustrate a medical use of the textile structure of the invention, respectively in the folded and unfolded position. 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. Figure 5 is a schematic illustration of the method of the invention which can be applied to allow the reversal of the frame by electric heating. DETAILED DESCRIPTION OF THE INVENTION

Thus, in connection with FIG. 1, the textile structure of the invention, as obtained with Rachel technology, such as for example with a Karl Mayer or Liba type loom, has been illustrated. One could still implement Comez hook technology, or a technology business chain.

In this case, it is a bonding wire structure 101 charmeuse type, incorporating son 103 made of shape memory material, and typically l0 nitinol, inserted in weft or cross-machine direction.

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

However, for these bonding wires, materials resistant to the training temperature of the shape memory material of the wires 103 may be chosen. For example, they may be of a mineral (glass or basalt) or metallic (steel) nature. stainless steel, nickel, etc.), and in this case, withstand higher subsequent treatment temperatures, thereby allowing the conventionally obtained textile structure to undergo shape learning at the conventional wire shape training temperatures. 103 entering its constitution.

FIG. 2 illustrates another variant, in which the shape memory wires 103 and 104 are oriented in the warp and in the weft directions. FIGS. 3a and 3b show an example of application of the textile structure of the invention as an implant.

FIG. 3a shows the implant in a "folded" situation, suitable for placing it in place or insertion in a location determined by the practitioner.

FIG. 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 use of the memory wires of form 303 and 303, oriented in the example described in the warp and weft directions.

FIGS. 4a to 4c show another application of the textile structure of the invention, namely the production of a blind intended to obscure on demand a panoramic roof of a motor vehicle.

Figure 4a is a sectional view 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 in line with the rear window of said vehicle (see Figure 4c).

Figure 4b shows the principle of operation of the blind. 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.

FIG. 5 is a diagram of the framer of a Rachel or hook type machine 20 incorporating a device for locally energizing 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 cursor in translation 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 the speed of the machine, an electric 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.

Claims (15)

REVENDICATIONS1. Knitted textile structure made by chain or Rachel mesh technology comprising threads or strips made of shape memory material (103, 104, 303, 304, 404), inserted in cross-direction, bonded together by knitting by means of textile threads of different nature (101), said son made of shape memory material remaining substantially rectilinear within the structure. Knitted textile structure according to claim 1, characterized in that threads or strips made of shape memory material are further inserted in the production direction, in that they remain substantially rectilinear within said structure and in that that they are related to the structure. 3. 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. 4. Knitted textile structure according to one of claims 1 and 2, characterized in that the width of the strips 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 are mono- or multi-filament yarns, and are made of a material chosen from the group comprising polyester, polyamide, polyethylene, polypropylene, metals or a mineral fiber of glass or basalt type. 6. Process for the production of a knitted textile structure according to one of claims 1 to 5, characterized in that it implements jet mesh technology with framer or Rachel technology multi-axial. 7. Method according to claim 6, characterized in that the shape memory weft son are heated in the phase of the raster return, by localized application of an electric voltage capable of inducing by Joule effect a local heating. 5 30 8. Method according to claim 7, characterized in that the application of the electrical voltage is carried out by means of two electrodes integrated on the overturning stitcher or in the passette of the framer of the trade chain or Rachel. 9. The method of claim 8, 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. 10 10. The method of claim 6, characterized in that the textile structure obtained undergoes after its elaboration forming a high temperature between 150 and 500 ° C. 11. A method for producing a fricot textile structure according to one of claims 1 to 5, characterized in that it implements a double needle bed, one of the two needle beds at least integrates son to shape memories according to one of the features described. ] 12. 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 development a double-acting form of learning to give it two different shapes to different temperatures, typically between 40 and 100 ° C and between 120 and 260 ° C. 25 13. Use of the knitted textile structure according to one of claims 1 to for the realization of medical or surgical implants. 14. Use of the knitted fabric structure according to one of claims 1 to 5 for the realization of an automotive blind or dwelling. 15. Use of the knitted fabric structure according to one of claims 1 to 5 for the production of molds, including pastry or industrial.