CZ325894A3 - Textile reinforcement for producing composite materials - Google Patents

Abstract

Textile reinforcement usable for the production of a composite material, consisting, when it is considered in place inside the said composite material after production, of two actual textile reinforcing layers placed on either side of a central layer endowing the said material with thickness, the said central layer consisting of a sheet based on synthetic fibres, of high unit titre, and which have received, before being converted into sheets, a treatment giving them a permanent waviness (or curl). It is characterised in that at least one of the textile reinforcing layers is covered with a fibrous web based on chemical fibres, of lower titre than that of the fibres forming the inner layer and which have also received a treatment giving them a permanent waviness or curl, the various layers being bonded together by needling.

Description

Field of the invention

AND

The invention relates to improvements in textile fittings which can be used to form composite materials, i.e. resin-based textile products (polyester or other), which are reinforced with a separate textile reinforcing fleece.

State of the art

So far, for example, fabrics, textile nets and nonwovens or combinations thereof are used as reinforcing materials in the field of composite materials.

In French Patent No. 2,646,422, the Applicant proposes a textile fitting adapted to create reinforcements of high thickness when it is necessary to produce elements for structures such as automobile bodies, cruise ships, tankers, etc., which, of course, have to exhibit high rigidity. Such a fitting comprises at least two layers of textile reinforcement arranged on one side and the other side of the middle layer, which actually creates the required thickness of the material. The armature is characterized in that said middle layer consists of a high-grade synthetic fiber web which has been subjected to a process of permanent crimping prior to forming, wherein the various layers are joined together by seaming or braiding.

The complex material thus produced is fully satisfactory with respect to the mechanical characteristics provided by the composite structure produced in the manner described.

Furthermore, this material is particularly suitable for forming complex structures by molding, for example a technique called η

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. ·. ... AW,. . The only drawback is that the seams between the individual layers reduce the deformation capacity and lead in particular to irregularities in the surface?

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SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improvement of this type. 5,. The textile material, which allows the advantages of the described structure to be retained, i.e. the possibility of deformation, high thickness and particularly high homogeneity of the composite material due to the internal fibrous web (the fibers behave like springs), so that very homogeneous ^{: the} distribution of the resin over the entire thickness of the material in all directions and its pile of trims is perfectly even.

The invention therefore relates to a new type of textile fitting useful for forming a composite material. This armature consists of two layers of textile reinforcement, which are arranged from one side to the other of the middle layer, which creates the material thickness. This middle layer consists of a high-fiber synthetic fiber web, which has been subjected to a continuous process prior to forming.

Ί curl. This armature is characterized in that at least one of the layers of the textile reinforcement is covered with a fiber web of chemical fibers of which the titer. is less than \ titre fiber ¹ constituting the inner layer and which have also been subjected to a shirring or permanent crimp, whereby jednotlivé.vrstvy are interconnected by needling:

One of; According to an embodiment of the invention, said textile armature is formed by a middle layer enclosed between two textile reinforcements, at least one of which is covered with a fibrous web.

According to a further variant, the armature is formed by a layer of fibers which is intended to produce a final thickness. The material is one of the sides covered with a stiffener covered with a fibrous web. *. formed composite material, the said material folded to ⁷ že.v final structure of the middle layer creates. The material thickness of the material has a textile reinforcement on both sides of the fabric.

Due to the fittings described in U.S. Patent No. 2,646,442, such a material exhibits improved deformation and forming properties, and; it. as a result of that. , the individual layers are not seamed together. Also.

....... maintains favorable stratification. Resin and also- the outer surface of the products is perfectly regular.

As a material for forming such a complex, materials similar to the subject of FR-A 2,646,442 can be used, in particular for implementing the inner layer as well as the two layers of textile reinforcement arranged on either side of the middle layer.

Thus, the inner layer is preferably formed from a nonwoven web produced by carding from synthetic fibers such as polyester, polypropylene, polyamide, polyethylene fibers, which have been subjected to appropriate shaping after. the purpose of permanent curl. These are high titer fibers, usually between 20 and 200 dtex, whose length is between 40 and 120 mm. Obviously, the use of finer fibers is eventually desirable, but this will increase the density of the structure, as well as the stratification of the resin in making a composite material, which is much more difficult, sometimes impossible, to make.

All types of conventional reinforcements can be used as textile reinforcements arranged on either side of the inner layer, such as parallel threads which are closely adjacent or spaced apart (bi-directional webs), the spunbond webs of fabric. can not stand alone; or. ' in combination'. Such reinforcements can normally be used to make composite materials such as glass fibers. -, .Fibrous web, which -. it covers at least one of the layers of textile reinforcement, it can be made of chemical fibers of the same or different nature from the material of the inner layer. These fibers are also subjected to a crimping process and are much finer. Poly ester, polyamide, polypropylene, polyethylene fibers having a titer of between 1.5 and 10 dtex, which are formed. Usually, they are used for conventional textile products such as ^{: 5} garments, home furnishings, filters are well suited for making this or these surface layers.

The interconnection of the different layers is preferably effected by mechanical needling, wherein the needles with the hooks facing each other allow the feeding of the surface fibers as well as the movement of the needles forwards and backwards of the stacked fibrous layers forming the whole complex.

In the case where the basic structure for making the material according to the invention consists only of a high-titre fibrous web, one side of which is covered with a textile web with a fiber web based on fine and curled fibers, the needles can be made with needles with hooks in the same direction that they penetrate the stacked textile material starting with the topsheet on the fine fiber base.

It is also possible to establish a connection between the different layers such that the needling is performed by means of a liquid jet, in particular a water jet. The advantages of this invention can easily be understood, by way of example only, but not by way of limitation. Example 1.

On a conventional needling machine equipped with needles with opposite hooks, a fitting according to the invention is produced by introducing a non-woven needle-punching machine over a pre-arranged lamination of textile webs folded as follows

- an inner layer consisting of a nonwoven-carded non-woven web of propylene polypropylene fibers of a titre of 70 dtex and a length of 90 nun, the fibers being crimped prior to cutting so that the ripple is permanent (in this case 2.3 waves per centimeter!) this fleece weighs about 250 g / m and its thickness is about mm;

two textile stiffeners arranged on either side of said inner layer, said textile stiffeners comprising a 450 g / m 2 glass fiber web obtained by dry shearing and non-woven; these glass fibers; they have a titre of 25 tex and a cut length of 50 mm.

On the one hand and on the other side of the assembly, i.e. on the outer sides of the layers of textile reinforcement, a fibrous web made of carded polyester crimped fibers of 3.3 dtex and a cut length of 40 mm is provided, the fibrous web having a weight of 60 g / m.

The needling operation takes place under the following conditions:

- material feed rate: 4 m per min.

Ampl 'amplitude displacement of needles: 60 mm

- 2 - needling density 45/50 beats per cm. After the needling is carried out, we obtain a structure having a thickness * r of about 4.5. mm, all fleeces are perfectly connected to each other.

Example 2

The procedure of Example 1 is repeated, but instead of folding the textile webs, one inner layer covered with a textile reinforcement and a fibrous web with the same characteristics and composition as in Example 1 is used.

The needling is carried out under the same conditions, but the needles have the hooks oriented in the same direction and the needling starts with the fibrous web.

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The achieved structure is folded in half, so that the peacock action is outside and the nonwoven web is on the base of high titer fibers inside. Thus, for example, a reinforcement of approx. 9 mm thickness is obtained compared to the previous example.

The materials according to the invention are very suitable for producing molded articles by injection molding or vacuum pressing. The composite materials formed in this way are very homogeneous and their surface is perfectly regular.

Of course, the invention is not limited to the embodiment described above, but covers all variants of fabrication according to this principle.

The joining of the different layers could also be done by double-needle punching or by using a water jet device.

AND

Thus, if it is preferred to bond the layers forming the materials of the invention in a single operation, bonding may be considered. the outer, sides after the inner-inner structure (middle layer and reinforcement associated with this layer) has been completed.

AND

Claims (4)

Claims kx ·. . 1) Textile -.armatura-for. forming - composite materials formed within a week. a composite material comprising two layers of textile reinforcement arranged on one side and the other side of the central layer forming the thickness of the material, said central layer being a fleece web; high titre synthetic fibers which have been preceded by a continuous web (or curl) process, characterized in that at least one of the layers of textile reinforcements is covered with a fiber web on the base; chemical fibers of a titre lower than the fiber constituting the inner layer, which has also been subjected to a process of continuous crimping or curling, the different layers being interconnected by needling. I lo AND 2. The textile fitting according to claim 1, characterized in that it is constituted by a middle layer enclosed between two textile reinforcements, at least one of which is covered by a fibrous web, before the composite material is made. 3. A textile fitting as claimed in claim 1, characterized in that, prior to making the composite material, it is formed by a high-titre fiber base layer which forms the thickness of the final material covered on one side with a fibrous web reinforcement. folded in half so that the final structure consists of a middle layer creating a material thickness, which is covered on one side and the other by a textile web with a fibrous web. Textile armature according to one of Claims 1 to 3, characterized in that the layer (s) of the textile reinforcement consist of a fibrous web optionally associated with other