FR2770093A1 - RIGIDIFICATION REINFORCEMENT OF A PARTY OF GARMENT MADE OF THERMOPLASTIC OR THERMOSETTING MATERIAL COMPRISING LONGITUDINAL FIBER OF RIGIDIFICATION - Google Patents

Abstract

The stiffener (1) is made from a fibre-reinforced thermoplastic or thermosetting material with reinforcing fibres which are curved so they lie parallel to the generating surface of the stiffener. The fibres include some (Fl) which are the same length as the whole stiffener and others (Fc) which are shorter and comprise 0 - 90 per cent of the stiffener's volume. The reinforcing fibres are of glass, carbon or polyamides, and have a diameter of 0.05 - 0.8 mm or 0.8 - 3 mm, depending on whether the stiffener is made by thermoforming, moulding, compression, injection or pultrusion or by overmoulding or coextrusion.

Description

RIGIDIFICATION REINFORCEMENT OF A PART OF GARMENT MADE

  IN THERMOPLASTIC OR THERMOSETTING MATERIAL

  COMPRISING LONGITUDINAL RIGIDIFICATION FIBERS

  The present invention relates to a reinforcement for stiffening a part of clothing made of thermoplastic or thermosetting material. It also relates and more particularly to any type of undergarment,

  a part needs to be stiffened.

  To date, in the prior art, the stiffening reinforcements of a part of clothing are generally made of metal, and sometimes already in

thermoplastic material.

  The reinforcements made of metal have an interesting rigidity due to the high modulus of elasticity, notably of steel, but also of other metals. However, they have certain disadvantages such as the lack of elastic memory causing residual deformation under certain stresses and / or washing operations, as well as a low

  protection against corrosion and / or oxidation.

  The thermoplastic reinforcements of the prior arts have overcome the problems of corrosion and oxidation, but require sections with high surface inertia and possibly a reinforcement of a load of short glass fibers, making it possible to ensure satisfactory rigidity, however lower. to that of steel. The short fibers used so far generally have a length of between 0.2 mm and 1 mm, lengths insufficient for their performance to be optimal in terms of stiffening, as will be seen in

detail later.

  The stiffening reinforcement according to the present invention aims to alleviate the problems presented by metallic or thermoplastic reinforcements to

abovementioned short fibers.

  As mentioned before, the frame used has a

  matrix made of thermoplastic or thermosetting material.

  Among the thermoplastic materials which can be used, there may be mentioned in particular: - aliphatic polyamide materials: polyamide 6-6 (PA 6- 6) polyamide 6 (PA 6) 35. Polyamide 11 (PA 11) polyamide 12 (PA 12) - materials aromatic polyamides:

polyamide 46 (PA 46) -

  - styrene materials: acrylonitrile - butadiene - styrene (ABS) acrylonitrile - styrene - acrylate (ASA) styrene - acrylonitrile (SAN) styrene - butadiene (SIB) 5.styrene - maleic anhydride (SMA) styrene - a - methylstyrene (S / MS) - polyolefin materials: polyethylene (PE) polypropylene (PP) - polyacetal materials: polyoxymethylene (POM) polycarbonate materials (PC) - saturated polyester materials: polyethylene terephthalate (PET) 15. polybutylene terephthalate (PBT) thermosetting materials, those which can be used in the context of the invention are in particular: - unsaturated polyester materials (UP); - polyepoxide materials (EP); - polyurethane materials (PUR); - polyacrylic materials (PMMA);

- polyimide materials (PI).

  The major characteristic of the stiffening reinforcements of the invention resides in the fact that they comprise stiffening fibers systematically oriented along arcs of curvature parallel to the

armature generator.

  In other words, said reinforcements are provided with fibers parallel to

  The medium arc forming their theoretical axis.

  This can be done according to several embodiments - the reinforcement can comprise at least one stiffening fiber of length equivalent to the total deployed length of the reinforcement, that is to say the sum of the lengths of the elementary arcs taken from one end of the frame to the other end. They are therefore fibers joining the

two ends of the frame.

  - The frame may include at least one stiffening fiber joining its two ends, as well as a certain percentage of fibers obeying the main characteristic, and whose length is greater than 5 mm. The percentage of these fibers is defined as being the ratio of the total volume of said fibers of length greater than 5 mm to the total volume of the reinforcement. The percentage provided by the invention is between 0% and%. - The reinforcement may include a percentage, defined according to the above criteria, of fibers whose length is greater than 5 mm. This percentage is also between 0% and 90%. In the last two cases, the fibers of length greater than 5 mm are of course of length strictly less than the length of the deployed reinforcement, and are distinguished from the fibers joining the two ends of said reinforcement. The size of the frame being able to vary according to the size of the garment which it stiffens, the length of the fibers can also vary according to the size of the frame, in particular when one places oneself in the first two embodiments. However, this is not an obligation, in particular

in the third mode.

  In all cases, the volume allocated to the matrix containing these fibers does not

may be less than 10%.

  To perform their function relative to the invention, the stiffening fibers must have a diameter of between 0.05 mm and 3 mm. Preferably, and depending on the material used, this diameter is chosen in a range between 0.1 mm and 3 mm. According to the invention, said material is chosen from glass, carbon or aromatic polyamides for which an aromatic group has been partially substituted for the main aliphatic chain. There can of course also be a combination of these materials. For structural reasons, the diameter of the glass fibers is between 0.2 mm and 2.5 mm, while that of the carbon fibers is approximately 0.1 mm. Finally, aromatic polyamides are used with diameters

between 2 mm and 3 mm.

  The diameter, and therefore the choice of material, also depends on the manufacturing process. Thermoforming, injection, compression molding and

  pultrusion require diameters between 0.05 mm and 0.8 mm.

  Overmolding and coextrusion require diameters between 0.8 mm

and 3 mm.

  According to a possible example, an aromatic polyamide which can be used in the context of the invention can be an isophthalic polyamide, which obeys the following chemical formula -N - CH2 - CH2 - CH2 - CH2- CH2 - CH2 - N - C \ il I 1 i 0o

H H O

  More generally, it is possible to use the aromatic polyamides available on the market, such as those which are known under the following trade names or trademarks Kevlar, Grivory, Arlen, Twaron, Ixef, etc. As a preferred application, the bra cups have been mentioned, but it is clear that these underwires can also be used for other articles, for example in men's shirts to reinforce shirt collars, or as part of clothing. professionals to strengthen

various parts of the garment.

  The basques, swimsuits, etc ... are also considered

equivalent to bras.

  The invention will now be described in more detail, with reference to the appended figures, for which: - Figure 1 shows a top view of a frame according to the invention via an example showing the orientation of the stiffening fibers; - Figure 2 shows in perspective a combination of different stiffening fibers in a frame; - Figure 3 shows a bra fitted with underwire according to this

invention.

  In these figures, the same references designate elements ensuring

the same function.

  Thus, the frame (1) according to the invention comprises stiffening fibers (Fn) oriented along curvatures (C) parallel to the external curvatures of said frame (1). In other words, the arcs of circle (C) of the stiffening fibers (Fn) have axes parallel to the generatrices (G) of the volume

constituting the frame (1).

  These fibers (Fn) having a high modulus of elasticity, they are therefore used optimally in the matrix when the reinforcement (1) is subjected to bending stresses in particular due to tensile stresses and in

  compression, for example at the ends of reinforcement (1).

  This geometry in fact allows the stiffening fibers (Fn) to contribute in their entirety to the bending behavior of the reinforcement, which

  is not the case in current structures.

  Indeed, in the case of use of short fibers not oriented in the prior art, the bending behavior of the reinforcement is mainly dependent on the intrinsic mechanical characteristics of the matrix used to coat the fibers. The reason is that the armatures of the prior art are generally manufactured according to an injection process using

  short fibers whose length is between 0.2 mm and 1 mm.

  The fibers being of length much less than the length and even the dimensions of the section of the reinforcement, they can in principle orient themselves in a completely random manner. However, the temperature of the mold being lower than the temperature of the plastic injected, the fibers tend to flatten on the surface and to align themselves parallel to the direction of flow.

  injection, that is to say also parallel to the walls of the mold.

  The rigidity of the reinforcement therefore also partly depends on the rate of these parallel fibers on the surface, which in turn depends on the material used for the matrix, which is either amorphous, or semi-crystalline, or crystalline. Inside the frame, the fibers being arranged anarchically, the rigidity is practically no longer a function only of the material chosen for the

  matrix, which is of course not the case for the invention.

  In the representation of the invention appearing in FIG. 1, a single fiber (Fn) is drawn. However, n is an integer, symbolizing the

  total number of fibers in the reinforcement, regardless of their length.

  The unitary graphic representation used simply aims to improve the

clarity of the drawing.

  According to a possible embodiment, the stiffening reinforcement (1) is produced by an injection molding process, and it comprises at least one stiffening fiber (FI), appearing in FIG. 2, of length equivalent to the total length deployed of the reinforcement (1), as well as a certain percentage of fibers whose length is greater than 5 mm, as

we saw it previously.

  The overmolding of at least one continuous fiber with a thermoplastic or thermosetting matrix in a mold, said matrix comprising a percentage of fibers greater than 5 mm, makes it possible to obtain a mixture of continuous fibers, mid-length fibers, and matrix . Insofar as the mold footprint has a section whose largest dimension is less than 5 mm, the orientation of the fibers according to the curvatures of

the armature is then automatic.

  In fact, the ratio of the widest section width of the reinforcement (1) to the length of the stiffening fibers (Fn) is less than 1, which means that said fibers cannot take on a shape orientation.

  transverse, but only a longitudinal orientation.

  The orientation of the fibers (Fn) along the curvature of the reinforcement necessarily results from the comparative dimensions of the mold and of the fibers, and from the injection molding process itself, involving a flow of material. The reinforcement (1) can also be produced by other manufacturing methods, such as thermoforming, compression molding, pultrusion, coextrusion, etc. In the case of thermoforming, the material used for the matrix has a surface appearance, of the plate or sheet type, from which the

  volume structure of the reinforcement (1).

  Compression molding preferably uses a powder-type raw material, or a preform, to produce the matrix of the frame, this raw material being inserted into a cavity undergoing compression aimed at softening said material to make it take the form of the imprint. In both cases, an almost isotropic structure can be obtained, making it possible to improve the torsional behavior of the reinforcement (1). This can of course also be provided with short fibers (Fc) of length exceeding 5 mm, existing in a certain percentage relative to the volume of said

frame (1).

  Pultrusion consists of an impregnation of the fibers (Fn), continuously, by a resin or more generally by a plastic material constituting the matrix. The assembly then passes through a guide, then a mold

  heater giving the frame (1) its final shape.

  This process is applicable to thermosetting and thermoplastic materials, although it is more common with the former. It then leads to more rigid structures than those which would be obtained with thermoplastics, but which have less elasticity, that is to say which do not return to their initial shape after application of stresses.

  mechanical, for example in torsion.

  However, if the response to mechanical stresses can be considered less good, the actual behavior, for example as a bra frame, is much better because

  much more comfortable for the user.

  The fibers, impregnated with resin, for example epoxy, exit from a nozzle and are then wound on a shaped mandrel making it possible to obtain, on either side of a longitudinal axis of said mandrel, two reinforcements (1) of same shape. At this point,

  impregnated fibers are still at a temperature above

  above the glass transition point, so they're still

  sufficiently soft to be formed on the mandrel.

  Pultrusion can also be associated with a filament winding, that is to say that filaments impregnated with the same resin, in sheets, include the aforementioned fibers. The pultruded impregnated fibers, as well as said filament winding,

  wrap around the same mandrel and polymerize there together.

  The advantage of this technique lies in the fact that the external coating improves the external surface of the reinforcement (1), standardizes and parallelizes the fibers, which has the effect of improving

  the mechanical response to traction and torsion.

  Coextrusion is also a continuous process, making it possible to coat an extruded synthetic matrix with a bundle consisting of fibers (Fn) to obtain a coextruded reinforcement (1). Said fiber bundle in this case only includes reinforcing fibers, excluding

  any additional material binding the bundle fibers together.

  In the last two cases, it is necessary to cut off the

reinforcements to the desired dimension.

  The stiffening fibers (Fn), (Fc), (FI) have a diameter which depends well

heard of the process used.

  Smaller diameters, between 0.05 mm and 0.8 mm are used for pultrusion, injection, thermoforming or compression molding. The last three require fibers with a small diameter because the compression of the materials they involve would cause the breaking of fibers with diameters

greater than the range provided.

  Similarly, during the shaping of the reinforcement intervening during the

  pultrusion, the fibers break when their diameter is too large.

  Diameters between 0.8 mm and 3 mm can be used for manufacturing processes such as overmolding or coextrusion. Overmolding indeed causes pressure on the plastic material constituting

  the matrix on the fibers (Fn). If these are too weak, they break.

  The same goes for the coextrusion process, in which the external plastic material exerts a strong pressure on the stiffening fiber or fibers. For the manufacture of reinforcements (1) according to the present invention, it is also possible to implement a coextrusion process which is applied not directly on fibers, but on a composite material including fibers from the outset. In this particular case, we can

  reduce the fiber diameter and bring it back to the previous interval.

  This particular coextrusion is in fact exerted on a central pultruded material, a composite for example based on polyethylene terephthalate (PET). This thermoplastic material brings a certain rigidity to the whole, but suffers from a

lack of elastic memory.

  Then, this composite central core is in a way sheathed by an elastic material which also prevents internal fibers or filaments from leaving the volume of the frame, which could have detrimental effects both on the fabric surrounding the frame and skin for people wearing

  garment with such a frame.

  The cladding produced by this coextrusion applied to a pultruded central core can be made of a polyacetal of the polyoxymethylene type. When using this reinforcement manufacturing process (1), it is also necessary to apply a hot post-forming to the

continuously coextruded product.

  Among the materials constituting the stiffening fibers (Fn), (FI), (Fc), and according to the methods used, it is intended to use, as mentioned, glass, carbon or aromatic polyamides for which have partially substituted an aromatic group for the main chain

  aliphatic, or a combination of at least two of these materials.

  Indeed, the modulus of elasticity in bending and in tension that these materials present make it possible to advantageously choose fibers whose Young's moduli are in a range between 10,000 Mpa and 280,000 Mpa. We can then adapt the rigidity of the frame (1) according to the conditions of use. As an example, the Young's modulus of carbon fibers represents the

  upper bound of the interval: E = 280,000 Mpa.

  By way of nonlimiting example, the stiffening reinforcement (1) can be produced by pultrusion or coextrusion of one of the materials mentioned above. The manufacturing processes mentioned are used according to the same general principle for short fibers and long fibers. The stiffening frame according to the invention is more particularly intended to stiffen a part of undergarment such as a bra, as it appears in FIG. 3. It is then inserted at the base of the cups,

that it stiffens.

Claims (14)

  1. stiffening frame (1) of a piece of clothing made of thermoplastic or thermosetting material, characterized in that said frame (1) comprises stiffening fibers (Fn) oriented along arcs of curvature (C) parallel to the volume generator (G) of said frame (1).   2. stiffening frame (1) of a piece of clothing according to claim 1, characterized in that it comprises at least one stiffening fiber (FI) of length equivalent to the total length of the frame. 3. stiffening frame (1) of a garment part according to claim 1, characterized in that it comprises at least one stiffening fiber (FI) of length equivalent to the total deployed length of the frame (1) and a percentage of the volume of said reinforcement (1) of fibers (Fc) whose length is greater than 5 mm and less than said total length deployed.   4. stiffening frame (1) of a garment part according to claim 1, characterized in that it comprises a percentage of the volume of the frame (1) of fibers (Fc) whose length is greater than 5   mm and less than the total deployed length of the reinforcement (1).   5. Reinforcement of stiffening (1) of a part of clothing according to one of   claims 3 and 4, characterized in that said percentage of the volume   of the reinforcement (1) of fibers (Fc) is between 0% and 90%.   6. stiffening frame (1) of clothing according to any one of   Claims 1 to 5, characterized in that the materials constituting the   stiffening fibers (Fn) (FI) (Fc) are chosen from glass, carbon or aromatic polyamides for which an aromatic group has been partially substituted for the main aliphatic chain, or a   combination of at least two of these materials.   7. stiffening frame (1) of clothing according to any one of   previous claims, characterized in that it is manufactured   using a process chosen from thermoforming, compression molding, injection, pultrusion and pultrusion associated with a filament winding.   8. stiffening frame (1) of clothing according to the preceding claim, characterized in that the diameter of the stiffening fibers   (Fn) (FI) (Fc) is between 0.05 mm and 0.8 rffm.   9. stiffening frame (1) of clothing according to any one of   Claims 1 to 6, characterized in that it is produced using a   process chosen from overmolding and coextrusion.   10. stiffening frame (1) of clothing according to the preceding claim, characterized in that the diameter of the stiffening fibers   (Fn) (Fl) (Fc) is between 0.8 mm and 3 mm.   11. stiffening frame (1) of clothing according to any one of   previous claims, characterized in that it is used for   stiffen the lower part of the cups of a bra, worn in   undergarment, basque or bathing suit.   12. stiffening frame (1) of clothing according to one of claims   1 to 10, characterized in that it is used to strengthen the collar of the shirts.   13. stiffening frame (1) of clothing according to one of claims   1 to 10, characterized in that it is used to reinforce parts of professional clothing.   14. Bra characterized in that it includes reinforcements according to one   any of claims 1 to 10.