EP0914780B1 - Thermoplastic or thermosetting brassiere frame including elongated stiffening fibres - 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

The present invention relates to a stiffening reinforcement for bra made of thermoplastic material or thermosetting.

Until now, in the prior art, stiffening reinforcements of a garment part are generally made of metal, and sometimes already in thermoplastic material.

The frames made of metal have a rigidity interesting due to the high modulus of elasticity especially of steel, but also other metals. They do however some disadvantages such as lack of elastic memory causing residual deformations under certain solicitations and / or washing operations, as well as a low protection against corrosion and / or oxidation.

Thermoplastic reinforcement of the prior art has compensated problems of corrosion and oxidation, but require sections with high surface inertia and possibly a reinforcement of a charge of short glass fibers, to ensure rigidity satisfactory, but lower than that of steel. Short fibers hitherto used have a length of between 0.2 mm and 1 mm, insufficient lengths so that their performance is optimal in terms of rigidification, as will be discussed in detail below.

Patent US-A-4,558,705 in the name of the applicant thus proposes reinforcements with a section that changes according to the available space in the geometry overall reinforcement. The envelope of the stiffening reinforcement is made of resin optionally reinforced with internal fibers, for example fibers of glass, which can take a random orientation, and even end up cross. These fibers do not allow a stiffening of the structure.

The prior art also known reinforcements having a rigidity obtained with fibers oriented along the axis of the reinforcements, but they are all necessarily obtained with the aid of fibers extending over all of their length.

Document FR-A-1338125 discloses, for example, a semicircular reinforcement, especially for bras, made from glass impregnated with epoxy resin and running along the entire frame.

US-A-5 167 891 relates to a process for making parts curvilinear plastic used especially as a bra frame. These parts can be made from two internal thermoplastic fibers, for example polyester, embedded in a plastic matrix to form a thermoplastic wire. This one, still warm, is shaped like a coil before being cut to give the curvilinear plastic piece. Again, Internal fibers extend all the way to the final piece.

US-A-5,624,386 relates to laminated bars thermoplastic composite material and thermoformable for orthopedic uses. According to the method described in this document, each bar is carried out using multiple layers superimposed containing fibers oriented in at least two different directions so as to improve the resistance to bending and twisting. The layers forming each bar are also reinforced by straight fibers extending from one end to the other said layers.

The stiffening reinforcement according to the present invention aims to overcome the problems with metal or thermoplastic reinforcement aforementioned, allowing to have an optimal rigidity by combining fibers of variable length and uniform orientation thereof. As mentioned before, the reinforcement used comprises a matrix made of thermoplastic or thermosetting material.

• les matières polyamides aliphatiques :
  • polyamide 6-6 (PA 6-6)
  • polyamide 6 (PA 6)
  • polyamide 11 (PA 11)
  • polyamide 12 (PA 12)
• les matières polyamides aromatiques :
  • polyamide 46 (PA 46)
• les matières styréniques :
  • acrylonitrile - butadiène - styrène (ABS)
  • acrylonitrile - styrène - acrylate (ASA)
  • styrène - acrylonitrile (SAN)
  • styrène - butadiène (SIB)
  • styrène - anhydride maléique (SMA)
  • styrène - α - méthylstyrène (S/MS)
• les matières polyoléfines :
  • polyéthylène (PE)
  • polypropylène (PP)
• les matières polyacétals :
  • polyoxyméthylène (POM)
• les matières polycarbonates (PC)
• les matières polyesters saturés :
  • polyéthylène téréphtalate (PET)
  • polybutylène téréphtalate (PBT)

Among the thermoplastic materials that may be used, mention may in particular be made of:

• aliphatic polyamide materials:
  • polyamide 6-6 (PA 6-6)
  • polyamide 6 (PA 6)
  • polyamide 11 (PA 11)
  • polyamide 12 (PA 12)
• aromatic polyamide materials:
  • polyamide 46 (PA 46)
• styrenic materials:
  • acrylonitrile - butadiene - styrene (ABS)
  • acrylonitrile - styrene - acrylate (ASA)
  • styrene - acrylonitrile (SAN)
  • styrene - butadiene (SIB)
  • styrene - maleic anhydride (SMA)
  • styrene - α-methylstyrene (S / MS)
• polyolefin materials:
  • polyethylene (PE)
  • polypropylene (PP)
• polyacetal materials:
  • polyoxymethylene (POM)
• polycarbonate materials (PC)
• saturated polyesters:
  • polyethylene terephthalate (PET)
  • polybutylene terephthalate (PBT)

• les matières polyesters insaturés (UP) ;
• les matières polyépoxydes (EP) ;
• les matières polyuréthannes (PUR) ;
• les matières polyacryliques (PMMA) ;
• les matières polyimides (PI).

Among the thermosetting materials, those that can be used in the context of the invention are in particular:

• unsaturated polyesters (UP);
• polyepoxide materials (EP);
• polyurethane materials (PUR);
• polyacrylic materials (PMMA);
• polyimide materials (PI).

The major characteristic of the stiffening reinforcements of the invention lies in that the stiffening fibers embedded in the matrix and oriented along arches of curvature parallel to the armature generator have a benefit of stiffening fibers whose length is greater than 5 mm and less than the total length of the armature.

In other words, said reinforcements have only fibers parallel to the arc medium forming their theoretical axis.

• l'armature ne peut comporter qu'un pourcentage de fibres dont la longueur est supérieure à 5 mm.
• l'armature peut comporter au moins une fibre de rigidification joignant ses deux extrémités, ainsi qu'un certain pourcentage de fibres dont la longueur est supérieure à 5 mm.

This can be done according to two embodiments:

• the reinforcement may comprise only a percentage of fibers whose length is greater than 5 mm.
• the reinforcement may comprise at least one stiffening fiber joining its two ends, as well as a certain percentage of fibers whose length is greater than 5 mm.

Fibers longer than 5 mm are well heard of length strictly less than the length of the armature deployed, and are distinguished fibers joining the two ends of said armature.

The size of the frame is likely to vary according to the size of the garment it stiffens, the length of the fibers can also vary according to the size of the frame, especially when one places oneself in the second mode of production. However, this is not an obligation, especially in the first fashion.

In any case, the volume allocated to the matrix containing these fibers can not be less than 10%.

To ensure their function in relation to the invention, the fibers of stiffening must have a diameter of between 0.05 mm and 3 mm. Of preferably, and depending on the material used, this diameter is chosen in a interval between 0.1 mm and 3 mm. According to the invention, said material is chosen from among the glass, carbon or aromatic polyamides for which partially replaced an aromatic group in the main chain aliphatic. There can of course also be a combination of these materials.

For structural reasons, the diameter of the glass fibers is included between 0.2 mm and 2.5 mm, whereas that of carbon fibers is around 0.1 mm. Finally, aromatic polyamides are used with diameters between 2 mm and 3 mm.

The diameter, and therefore the choice of the material, also depends on the process Manufacturing. Thermoforming, injection, compression molding and pultrusion require diameters between 0.05 mm and 0.8 mm. Overmoulding and coextrusion require diameters between 0.8 mm and 3 mm.

According to one possible example, an aromatic polyamide that may be used in the context of the invention may be an isophthalic polyamide, which obeys the following chemical formula:

More generally, it is possible to use polyamides aromatic substances available on the market, such as those known trade names or the following trademarks: Kevlar, Grivory, Arlen, Twaron, Ixef, etc.

As an application, bra cups were mentioned, but it is clear that these frames can also be used for other items, not claimed for example in the men's shirt to reinforce shirt collars, or as part of professional clothing to reinforce various parts of the garment.

The corsets, swimsuits, etc ... are moreover considered as equivalent to bra.

• la figure 1 représente en vue de dessus une armature selon l'invention montrant via un exemple l'orientation des fibres de rigidification ;
• la figure 2 représente en perspective une combinaison de différentes fibres de rigidification dans une armature ;
• la figure 3 montre un soutien-gorge équipé d'armatures selon la présente invention.

The invention will now be described in more detail with reference to the appended figures for which:

• FIG. 1 is a plan view of an armature according to the invention showing, by way of example, 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 equipped with frames according to the present invention.

In these figures, the same references designate elements ensuring the same function.

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

These fibers (Fn) having a high modulus of elasticity, they are therefore optimally used in the matrix when the reinforcement (1) is subjected bending forces, particularly due to tensile stresses and compression, for example reinforcing ends (1).

This geometry makes it possible for the stiffening fibers (Fn) contribute in their entirety to the bending behavior of the reinforcement, which is not the case in the current structures.

Indeed, in the case of using non-oriented short fibers of the arts previous, the bending behavior of the reinforcement is mainly depending on the intrinsic mechanical characteristics of the matrix used to coat the fibers. The reason is that the frames of the prior art are generally manufactured using an injection process using fibers short lengths between 0.2 mm and 1 mm.

The fibers being of length much shorter than the length and even dimensions of the armature section, they can in principle be oriented totally random way. However, the temperature of the mold being less than the temperature of the plastic material injected, the fibers tend to flatten on the surface and align with the direction of flow injection, that is to say also parallel to the walls of the mold.

The rigidity of the reinforcement therefore also depends partly on the rate of these parallel fibers at the surface, which in turn depends on the material used for the matrix, which is either amorphous, semi-crystalline, or crystalline.

Inside the frame, the fibers being arranged anarchically, the rigidity is practically no longer a function 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. fiber (Fn) is drawn. However, is any integer, symbolizing the total number of fibers contained in the armature, regardless of their length. The unitary graphical representation used is simply intended to improve the clarity of the drawing.

According to a possible embodiment, the reinforcement (1) of stiffening is performed by an injection overmoulding process, and it comprises at least one least one stiffening fiber (Fl), appearing in FIG. equivalent to the total deployed length of the armature (1), as well as a certain percentage of fibers (Fc) whose length is greater than 5 mm, as has been seen previously.

Overmolding at least one continuous fiber with a matrix thermoplastic or thermosetting in a mold, said matrix having a fiber percentage greater than 5 mm, makes it possible to obtain a mixture of continuous fibers, mid-length fibers, and matrix. In the the extent to which the mold cavity has a section whose largest dimension less than 5 mm, the orientation of the fibers following the curvatures of the frame is then automatic.

Indeed, the ratio of the largest section width of the armature (1) to the length of the stiffening fibers (Fn) is less than 1, which implies that said fibers can not take a pace orientation transverse, but only longitudinal orientation. The orientation of the fibers (Fn) according to the curvature of the reinforcement results necessarily compared dimensions of the mold and the fibers, and the injection molding process itself, involving a flow of material.

The armature (1) can also be realized via other methods of manufacturing, such as thermoforming, compression molding, pultrusion, coextrusion, etc.

In the case of thermoforming, the material used for the matrix is of surface appearance, of plate or sheet type, from which the volume structure of the armature (1):

Compression molding preferably uses a raw material of pulverulent type, or a preform, to make the matrix of the reinforcement, this raw material being inserted into an impression undergoing a compressing to soften said material to make it take the form of the impression.

In both cases, a quasi-isotropic structure can be obtained, allowing to improve the torsional behavior of the armature (1). This one is also with short fibers (Fc) of length exceeding 5 mm, existing according to a certain percentage in relation to the volume of frame (1).

Pultrusion consists of continuous impregnation of the fibers (Fn) by a resin or more generally a plastic material constituting the matrix. The assembly then passes through a guide, then a heating mold conferring on the frame (1) its final form.

This process is applicable to thermosetting materials and thermoplastics, although it is more common with the first named. he leads then to more rigid structures than those which one would obtain with thermoplastics, but which have less elasticity, that is to say which do not return to their original form after applying constraints mechanical, for example in torsion.

However, if the response to mechanical stress can be considered as less good, the actual behavior, for example as a frame of bra, is much better because much more comfortable for the user.

The fibers, impregnated with resin for example epoxy, leave a nozzle and are then wound on a mandrel shape to obtain, from and other of a longitudinal axis of said mandrel, two armatures (1) likewise form. At this point, the impregnated fibers are still at a temperature above the glass transition point, and so they're still soft enough 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 layers, encompass the aforementioned fibers. Pultruded impregnated fibers, as well as said filament winding, wrap around the same mandrel and polymerize together. The advantage of this technique lies in the fact that the outer topping improves the outer surface of the frame (1), standardizes and parallels the fibers, which has the effect of improving the mechanical response to traction and torsion.

Coextrusion is also a continuous process, allowing to coat extruded synthetic matrix a bundle consisting of fibers (Fn) to obtain a frame (1) coextruded. Said bundle of fibers does not include in this only reinforcing fibers, to the exclusion of any additional material the fibers of the beam between them.

In the last two cases, it is necessary to cut reinforcements to the desired size.

The stiffening fibers (Fn), (Fc), (Fl) have a diameter that depends well understood from the process used.

Smaller diameters between 0.05 mm and 0.8 mm are used for the pultrusion, injection, thermoforming or compression molding. The the last three require small diameter fibers because the compression of materials they imply would cause the breakage of fibers with diameters greater than the range provided.

Similarly, during the shaping of the armature intervening during the pultrusion, the fibers break when their diameter is too big.

Diameters between 0.8 mm and 3 mm can be used for manufacturing processes such as overmolding or coextrusion. The overmoulding causes a pressure of the plastic material constituting the matrix on the fibers (Fn). If they are too weak, they break.

The same applies to the coextrusion process, in which the material external plastic exerts a strong pressure on the stiffening fiber (s).

For the manufacture of reinforcements (1) according to the present invention, it is It is also possible to implement a coextrusion process which does not apply directly to fibers, but to a composite material including from the beginning fibers. In this particular case, we can reduce fiber diameter and bring it back to the previous interval.

This particular coextrusion is actually done on a central material pultruded, a composite for example based on polyethylene terephthalate (FART). This thermoplastic material brings a certain rigidity to the whole, but suffers from a lack of elastic memory.

Then, this central composite core is somehow sheathed by a elastic material which prevents in addition that fibers or filaments internals do not come out of the frame volume, which could have effects detrimental to both the fabric surrounding the armature and the skin of the people wearing a garment with such a frame.

The sheathing achieved by this coextrusion applied to a central core pultruded can be made of a polyacetal polyoxymethylene type.

When this reinforcement manufacturing method (1) is used, it is also necessary to apply a hot postform to the product coextruded in continued.

Among the materials constituting the stiffening fibers (Fn), (FI), (Fc), and according to the methods used, it is planned to use, as mentioned, the glass, carbon or aromatic polyamides for which we have partially substituted an aromatic group in the main chain aliphatic, or a combination of at least two of these materials.

Indeed, the modulus of elasticity in flexion and traction presented by these materials make it possible to advantageously choose fibers whose modules Young's range is in the range of 10,000 MPa to 280,000 MPa. We can then adapt the rigidity of the frame (1) according to the conditions of use.

By way of example, the Young's modulus of carbon fibers represents the upper bound of the range: E = 280,000 MPa.

By way of non-limiting example, the stiffening armature (1) can be made by pultrusion or coextrusion of one of the mentioned materials before.

The mentioned manufacturing processes are used according to the same principle general for short fibers and long fibers.

Claims (7)

1. Stiffening support (1) for a brassiere, made from a thermoplastic or thermosetting material and containing stiffening fibres (Fn) integrated in a matrix and oriented along arcs of curvature (C) parallel with the generatrix (G) of the volume of said support (1), characterised in that a percentage of the volume of the support (1) is made up of stiffening fibres (Fc), the length of which is in excess of 5 mm and shorter than the total length of the support (1), the volume of the matrix not being less than 10% of the total volume of the support (1).
2. Stiffening support (1) for a brassiere as claimed in claim 1, characterised in that it contains at least one stiffening fibre (FI) of a length equivalent to the total length of the support.
3. Stiffening support (1) for a brassiere as claimed in any one of the preceding claims, characterised in that the materials constituting the stiffening fibres (Fn) are selected from glass, carbon or aromatic polyamides for which an aromatic group partially substitutes for the main aliphatic chain, or a combination of at least two of these materials.
4. Stiffening support (1) for a brassiere as claimed in any one of the preceding claims, characterised in that it is manufactured by means of a process selected from heat forming, compression moulding, injection, pultrusion and pultrusion accompanied by filament winding.
5. Stiffening support (1) for a brassiere as claimed in the preceding claim, characterised in that the diameter of the stiffening fibres (Fn) is between 0.05 mm and 0.8 mm.
6. Stiffening support (1) for a brassiere as claimed in any one of claims 1 to 3, characterised in that it is manufactured by a process selected from over-moulding and co-extrusion.
7. Stiffening support (1) for a brassiere as claimed in the preceding claim, characterised in that the diameter of the stiffening fibres (Fn) is between 0.8 mm and 3 mm.

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