WO2006053978A1

WO2006053978A1 - Ventilated reinforcement and method for making same

Info

Publication number: WO2006053978A1
Application number: PCT/FR2005/002833
Authority: WO
Inventors: Gilbert Chomarat
Original assignee: Gilbert Chomarat
Priority date: 2004-11-16
Filing date: 2005-11-16
Publication date: 2006-05-26
Also published as: FR2877955B1; FR2877955A1

Abstract

The invention concerns a reinforcement product for making composite materials, consisting of a mat containing first sections of oriented filaments (1a) made of a first type of synthetic material, having been, prior to being shaped into a mat, processed to be permanently curled, second sections of filaments (2a) made of a second type of synthetic thermoplastic-like material, as well as sections of reinforcing fiber filaments (20a). The second sections of filaments (2a) made of a second type of synthetic thermoplastic-like material have a melting point lower than that of the first sections of filaments (1a) made of a first type of synthetic material. The sections of filaments partly adhere to one another through the second sections of materials (2a) made of a second type of synthetic thermoplastic-like material.

Description

AERIAL REINFORCEMENT PRODUCT AND METHOD FOR

His realization

TECHNICAL FIELD OF THE INVENTION The present invention relates to an improvement made to thick textile reinforcement used for the production of composite materials, that is to say of resin-based articles (polyester or other) armed with a textile web. reinforcement.

To date, depending on the desired applications and characteristics, the reinforcing structures used in the field of composites are, for example, fabrics, textile grids, nonwovens, or combinations of such elements.

A first necessary characteristic of these textile frames, when it is desired to produce elements such as vehicle bodies, pleasure boats, tanks, is that they have a high thickness in order to give composite materials a high degree of rigidity, in particular thanks to their thick.

Thus, the French patent FR 2,646,442 describes a textile reinforcement constituted by at least two textile reinforcement layers themselves, arranged on either side of a central layer giving the thickness to said material, and characterized by the fact that that said central layer is a mattress made by carding synthetic fibers, for example polyester, of high unitary title, and which have received prior to their mattress forming a treatment imparting to them a corrugation or permanent crinkling, the different layers being linked together by sewing / knitting.

However, one of the drawbacks of the product obtained lies in the fact that the bonding seams of the various layers between them limit the production of structures of complex shape obtained by molding, for example according to the techniques known as "injection molding with injection molding. "or" vacuum molding ". Indeed, the connection seams of the different layers between them introduce irregularities in the deformation capacities, limit the deformation capacities of the textile reinforcement before molding, and can lead to defects in surface appearance of the composite material after molding .

To remedy these risks of surface appearance defects, patent EP 0 659 922 proposes an improvement consisting in covering at least one of the textile reinforcing layers with a fibrous web based on chemical fibers, and in ensuring the cohesion of the different layers by needling. The document EP 0 694 643 proposes to improve the surface condition of the composite material comprising a reinforcement such as that described in patent FR 2,646,442, and furthermore proposes to adapt certain technical characteristics such as the dimensional stability of the product. or the possibility of deformation, depending on the applications into which such a material enters. To do this, to the textile reinforcement which is the subject of patent FR 2,646,442, is added a veil of synthetic fiber at least against one of the outer faces of the complex, the bonding of the veil being carried out either by bonding to the outside the textile reinforcement, or through the seams linking the different layers of the textile reinforcement between them.

The multilayer nature of the above reinforcements, as well as the irregularities of their deformation capacity before molding, are substantial disadvantages. Indeed, the fact that the frame has several layers requires to provide suitable means to ensure the cohesion between them of different layers. And whatever these connecting means, they always lead to limit and / or disturb the deformation capacity of the armature, thus making it poorly suited to use in injection molding techniques or by molding under empty, since leading to defects of the composite material after molding. In addition, the intermediate layer of the above reinforcements is free of reinforcing fibers, so that the resin is not reinforced in this intermediate layer, and is a zone of lower mechanical strength and may contain bubbles, to crack.

WO 2005/049906 A1, published after the priority date, discloses a thin coherent bonding web, composed of co-melded filaments of glass and thermoplastic material processed in a card, and glued by hot pressing on a support.

SUMMARY OF THE INVENTION The problem proposed by the present invention is to obtain a textile reinforcement having a sufficient thickness and giving the composite material satisfactory rigidity properties after molding, having a regular bending deformation capacity, having great flexibility for be deformed and placed effectively in a mold before injection, and having a coherence and satisfactory holding for necessary manipulations before molding. The invention also aims to design such a frame that can be manufactured economically by industrial processes. To achieve these and other objects, the invention proposes a reinforcing product that can be used for producing composite materials, comprising an aerated mattress based on first sections of filaments made of a first type of synthetic material, oriented, having previously received mattresses a treatment imparting them a permanent curling; according to the invention:

the first sections of filaments are monobrins of high unitary titre,

said mattress further comprises at least second sections of filaments made of a second type of synthetic material of an oriented thermoplastic nature, having a melting point lower than that of the first sections of filaments in a first type of synthetic material,

said mattress further comprises sections of filaments of reinforcing fibers,

- The sections of filaments partially adhere to each other by the second sections of filaments in a second type of thermoplastic synthetic material.

Thus, the reinforcing product is constituted substantially homogeneously in a single relatively thick main layer, for example about 3 cm thick, and has an internal cohesion that does not require additional methods of bonding with added material, or sewing / knitting. During an overmolding of such a reinforcing product, the resin flows easily between the single strands which themselves maintain the permeability due to their elasticity and their crimp which separate the filaments from each other.

At least some of the first sections of permanently crimped filaments within the reinforcing product may advantageously have a state of partial compression giving them elastic deformation or prestressing. This improves the consistency and strength of the frame before molding, while maintaining the flexibility and regularity of bending.

The first sections of monofilament filaments permanently crimped can advantageously have a linear density of 50 to 150 decitex, preferably 70 to 140 decitex.

The material of the second sections of filaments into a second type of synthetic material of thermoplastic nature can be chosen from the group comprising polyester, polyolefins, polyamides, polyacrylonitriles, polyethylene, polyethylene terephthalate and polybutylene terephthalate. According to an advantageous embodiment, the sections of filaments of reinforcing fibers may comprise sections of glass filaments. Alternatively or in addition, the sections of reinforcing fiber filaments may comprise sections of natural filaments such as Hn, hemp, sisal, jute, or wool.

It may be advantageous to introduce in the mixture sections of mixed fiber filaments which serve as both sections of reinforcing fiber filaments and second sections of filaments of a second type of synthetic material of thermoplastic nature. The sections of mixed fiber filaments come from co-mixed mixed yarns composed of glass filaments and filaments of an organic thermoplastic material having a lower melting temperature than the first sections of filaments of the first type of synthetic material. This reduces the number of fibers that must be assembled in the mixture at the base of the product, and this simplifies the development.

In an advantageous embodiment, at least one external reinforcing layer may be affixed to at least one of the faces of the reinforcing product.

For example, the outer reinforcing layer may be a web of continuous and parallel son.

It is also conceivable that the outer reinforcing layer is a fiber fabric oriented in at least two directions, or a finishing veil. According to another aspect, the invention proposes a process for producing a reinforcing product as defined above; the method comprises the following steps: a) preparing a homogeneous mixture of first sections of filaments in a first type of synthetic material, second sections of filaments in a second type of synthetic material having a thermoplastic nature and having a lower melting temperature than first sections of filaments in a first type of synthetic material, and sections of reinforcing fiber filaments, b) treating this mixture of sections of filaments in a card to produce an orientation of the sections of filaments and thus forming an oriented mattress, c ) heating the resulting oriented mattress to make the second filament sections adhesive to a second type of thermoplastic material of lower melting temperature, d) cooling the mattress.

Preferably, the method may comprise an intermediate step of compressing the constituents by reducing the thickness of the mattress and maintaining this reduction in thickness, during or following the heating step c), and this until in step d) of cooling. One thus favors, by this compression partial, the approximation of the sections of filaments against each other, and thus the adhesion of the sections of filaments to each other.

It is possible, between steps b) of carding and c) of heating, to provide an intermediate step during which at least one external reinforcing layer is applied to at least one of the faces of the mattress.

SUMMARY DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, with reference to the accompanying figures, in which:

- Figure 1 is a schematic perspective view illustrating a reinforcement product structure according to a first embodiment of the present invention;

- Figure 2 schematically illustrates an embodiment of manufacturing plant of the reinforcing product according to Figure 1;

FIG. 3 is a sectional side view partially illustrating the reinforcing product manufacturing facility according to the embodiment of FIG. 2;

- Figure 4 is a sectional side view partially illustrating the manufacturing facility during manufacture of the reinforcing product according to Figure 5; and FIG. 5 is a schematic perspective view illustrating a reinforcement product structure according to a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 2, which schematically illustrates a manufacturing facility of a reinforcing product according to an embodiment of the present invention.

This installation firstly comprises a reserve 1 of first sections of filaments 1a in a first type of synthetic material, as well as a reserve 2 of second sections of filaments 2a in a second type of synthetic material having a thermoplastic nature having a temperature of less melting than that of the first sections of filaments 1a in the first type of synthetic material. The installation further comprises a reserve 20 of sections of reinforcing fiber filaments 20a.

The first sections of filaments 1a in the first type of synthetic material are monobrins of high unitary title, having received a prior treatment giving them a permanent crimp. The linear density of these first sections of filaments 1a may advantageously be between 50 and 150 dTex.

The three reserves 1, 2 and 20 of sections of filaments then suitably feed a card 3. A mechanical card 3 may be used such as those conventionally used in the textile industry, comprising a rotating cylinder equipped with teeth or needles. which rotate in front of workers to drive the filament sections by painting them, thereby producing a continuous mattress 4 in which the filament sections 1a, 2a and 20a are preferably oriented in the longitudinal direction 11 of the mattress 4.

Alternatively, a pneumatic card can be used, generating a flow of air which directs the sections of filaments by painting them.

In the embodiment of FIG. 2, the mattress 4 is then heated by a heating device 6. The heating temperature is sufficient to give adhesive properties to the second sections of filaments 2a in a second type of synthetic material of a thermoplastic nature contained in FIG. the mattress 4 of fibers. The temperature is advantageously chosen only slightly lower than the melting temperature of the second filament sections 2a in a second type of synthetic material of thermoplastic nature, whose melting temperature is lower than that of the first sections of filaments 1a in the first type of filament. synthetic material. For example, for polyethylene, a temperature of about 120 ° C-140 ° C will be selected.

At the outlet of the heating device 6, a coherent mattress 5 is collected whose internal cohesion is ensured by the adhesion of the second sections of filaments 2a to a second type of synthetic material of a thermoplastic nature.

The constituents of the coherent mat can then be allowed to cool to ambient air.

Preferably, downstream of the heating device 6, there is provided a cooling device 7 for cooling the constituents and immobilizing the second sections of filaments 2a in a second type of synthetic material of a thermoplastic nature, thereby freezing the dimensional characteristics of finished textile reinforcement 8.

The melting temperatures of the first sections of filaments 1a in a first type of synthetic material and sections of reinforcing fiber filaments 20a are higher than that of the second sections of filaments 2a in a second type of synthetic material with a thermoplastic nature. first sections of filaments 1a in a first type of synthetic material and the sections of reinforcing fiber filaments 20a do not undergo any transformation during heating of the mattress 4 at a temperature slightly lower than the melting temperature of the second filament sections 2a in one second type of thermoplastic synthetic material.

Thus, the first sections of filaments 1a in a first type of synthetic material retain all their properties (of shape, of elasticity, etc.) and confer on the coherent mattress 5 an airy and elastic structure, resulting from their permanent crimping. . The sections of reinforcing fiber filaments also retain all their properties (shape, strength, etc.) and give the coherent mattress a certain endurance.

This elastic structure is advantageous in a molding process where large deformation capacities are required of the reinforcing product.

In addition, the aerated structure of the textile reinforcement allows an easier and more homogeneous distribution of an injected resin for example during the molding of the finished textile reinforcement 8 to obtain a reinforced composite.

By this process, a textile reinforcement having a sufficient thickness and a suitable distribution of reinforcing fibers is also obtained to give the composite material satisfactory rigidity properties after molding. The textile reinforcement has a capacity of deformation by regular bending, a great flexibility to be deformed and placed efficiently in a mold before injection, and has a satisfactory coherence for the necessary manipulations before molding.

1, which illustrates in perspective on a larger scale the structure of the finished textile reinforcement 8, formed of sections of filaments 1a, 2a and 20a carded, preferentially oriented in the longitudinal direction 1 January.

In the embodiment illustrated in FIG. 2, the material of the second sections of filaments 2a in a second type of synthetic material of thermoplastic nature is chosen from the group comprising polyester, polyolefins, polyamides, polyacrylonitriles and polyethylene. polyethylene terephthalate, or polybutylene terephthalate.

In this same embodiment illustrated in Figure 2, it can further be provided that the sections of reinforcing fiber filaments 20a comprise sections of glass filaments.

It may be advantageous to provide that the sections of reinforcing fiber filaments 20a comprise sections of natural filaments such as the linen, hemp, sisal, jute, or wool, in addition to or instead of sections of glass filaments.

In the embodiment illustrated in FIG. 3, compression means 9a and 9b located after the heating device 6 and located just before the cooling device 7 are provided. Thus, the mattress 4 coming from the card 3 is heated, then is subjected by pressing means 9a and 9b a partial compression of the constituents by reducing the thickness of the mattress, followed by cooling. The pressing of constituents once heated within the mattress

4 allows a better adhesion of the filament sections 1a, 2a and 20a to each other, while maintaining an airy or porous character.

The filament sections 1a, 2a and 20a may thus have a partial compression state resulting from the reduction in thickness of the mattress 4 by the pressing means 9a and 9b.

Alternatively or additionally, the partial compression of the permanent crimp filament sections 1a can be performed between the carding step and the heating step, by performing a hydraulic or mechanical needling.

The partial compression of the sections of filaments 1a with permanent crimping gives them an elastic deformation or elastic prestress whose existence can be seen in the finished reinforcement product: the prestressed unitary filaments tend to elastically relax when they are separated from the adjacent filaments, for example by cutting.

In Figure 4 is schematically illustrated a variant of the embodiment of Figure 3, wherein on the upper face of the mattress 4 is applied an outer reinforcing layer 10 which is then made adherent to the mattress 4 by heating and compression.

In the embodiment of FIG. 4, the outer reinforcing layer 10 may advantageously be a sheet of continuous and parallel threads.

Alternatively, the outer reinforcing layer 10 may be a fiber fabric oriented in at least two directions.

FIG. 5, which illustrates in perspective on a larger scale, the structure of the finished textile reinforcement 8, formed of sections of filaments 1a, 2a and 20a that are carded, preferably oriented in the longitudinal direction 11, and comprising on its upper face the outer reinforcing layer 10.

In the embodiments illustrated in FIGS. 3 and 4, the pressing means 9a and 9b provide a compression of the constituents by reducing the the thickness of the mattress 4 and the maintenance of this reduction in thickness to the cooling device 7. In the more particular context of the embodiment illustrated in FIG. 4, the pressing means 9a and 9b also ensure the plating of the layer external reinforcement 10 against the mattress 4. They can also be heated to ensure heating of the assembly to a temperature ensuring sufficient softening and adhesion of the second sections of filaments 2a in a second type of thermoplastic contained thermoplastic material in the composite fibers constituting the mattress 4. Alternatively, warming can be provided by hot sources such as infrared radiation sources upstream of the rollers, and the rollers 9a and 9b compress the constituents without heating them.

At the outlet of the cooling device 7, by the effect of the sufficient softening of the second filament sections 2a into a second type of synthetic material of thermoplastic nature, then by the cooling effect which freezes them, the external reinforcing layer 10 adheres to the coherent mattress 5, and the filament sections 1a, 2a and 20a also adhere to each other.

In the products and processes described above, it may be advantageous to introduce into the mixture sections of mixed fiber filaments which serve as both sections of reinforcing fiber filaments 20a and second sections of filaments 2a. a second type of thermoplastic synthetic material. The mixed fiber sections come from co-mixed mixed yarns composed of glass filaments and filaments of another organic thermoplastic material having a lower melting temperature than the first sections of filaments 1a in a first type of synthetic material. In this case, the card 3 is powered by only two reserves of wire sections.

The reinforcement product thus obtained is sufficiently homogeneous and coherent to allow control of its handling and its deformations when used in injection molding techniques or by vacuum molding, and to avoid defects in the composite material. after molding.

In particular, good molding results can be obtained with reinforcing complexes according to the following examples of the present invention: EXAMPLE 1 Carded complex comprising:

- 40 to 60 g / m ² of polyolefin thermofiante fiber, of 2 to 6 denier, length 38 to 50 mm, 150 to 250 g / m ² polypropylene monofilament crimped fiber, of the title 70 to 140 decitex, of straight cutting length 40 to 150 mm, having from 1.5 to 5.5 ripples per centimeter,

- about 900 g / m ² of chopped fiberglass, with a filament diameter of 11 to 15 μ, having a base titre of 33 to 45 decitex, length 35 to 55 mm,

a synthetic fiber or glass fiber surface fleece of 10 to 40 g / m ² .

Example 2

Carded complex comprising:

- 40 to 100 g / m ² of polyolefin thermofiante fiber, of 2 to 6 denier, length 38 to 50 mm,

150 to 250 g / m ² polypropylene monofilament crimped fiber, of the title 70 to 140 decitex, of straight cutting length 40 to 150 mm, having from 1.5 to 5.5 ripples per centimeter,

Approximately 1200 g / m ² of chopped fiberglass, with a filament diameter of 11 to 15 μ, having a base titre of 33 to 45 decitex, of length 35 to 55 mm,

a synthetic fiber or glass fiber surface fleece of 10 to 40 g / m ² .

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof within the scope of the claims below.

Claims

1 - Reinforcing product usable for the production of composite materials, comprising a mattress (4) aerated based on first sections of filaments (1 a) in a first type of synthetic material, oriented, having received prior to their forming into form of mattress a treatment communicating a permanent crimp, characterized in that:

the first sections of filaments (1 a) are monobrins of high unitary titre,

said mattress (4) further comprises at least second sections of filaments (2a) made of a second type of synthetic material of an oriented thermoplastic nature, having a melting temperature lower than that of the first sections of filaments (1 a) in a first type of synthetic material,

said mattress (4) furthermore comprises sections of filaments of reinforcing fibers (20a),

- The sections of filaments (1a, 2a, 20a) partially adhere to each other by the second sections of filaments (2a) in a second type of synthetic material of thermoplastic nature.

2 - reinforcing product according to claim 1, characterized in that at least some first sections of filaments (1 a) permanently crimped have a partial compression state conferring elastic deformation or prestressing.

3 - Reinforcing product according to one of claims 1 or 2, characterized in that the material of the second sections of filaments (2a) in a second type of synthetic material of thermoplastic nature is chosen from the group comprising polyester, polyolefins polyamides, polyacrylonitriles, polyethylene, polyethylene terephthalate, polybutylene terephthalate.

4 - reinforcing product according to any one of claims 1 to 3, characterized in that the sections of reinforcing fiber filaments (20a) comprise sections of glass filaments. 5 - Reinforcement product according to any one of the claims

1 to 4, characterized in that the sections of filaments of reinforcing fibers (20a) comprise sections of natural filaments such as linen, hemp, sisal, jute, wool.

6 - reinforcing product according to any one of claims 1 to 5, characterized in that it comprises sections of mixed fiber filaments from co-mixed mixed son composed of glass filaments and filaments of a thermoplastic material organic having a melting temperature less than that of the first sections of filaments into a first type of thermoplastic material.

7 - reinforcing product according to any one of claims 1 to 6, characterized in that on at least one of its faces is affixed at least one outer reinforcing layer (10).

8 - reinforcing product according to any one of claims 1 to 7, characterized in that the outer reinforcing layer (10) is a continuous and parallel son ply.

9 - reinforcing product according to any one of claims 1 to 8, characterized in that the outer reinforcing layer (10) is a fiber fabric oriented in at least two directions, or a finishing web.

10 - Process for producing a reinforcing product according to any one of claims 1 to 9, characterized in that it comprises the following steps: a) a homogeneous mixture of first sections of filaments (1 a) is prepared in a first type of synthetic material, second sections of filaments (2a) in a second type of synthetic material of thermoplastic nature and with a lower melting point than the first sections of filaments (1 a) in a first type of synthetic material, and sections of reinforcing fiber filaments (20a), b) treating said mixture of filament sections in a card (3) to produce an orientation of the filament sections and thereby forming an oriented mattress (4), c) heating the resulting oriented mattress (4) to make the second filament sections (2a) adhesive to a second type of thermoplastic material of lower melting temperature, d) cooling says the mattress (4).

1 1 - Process according to claim 10, characterized in that it comprises, during or following the heating step c), a compression of the constituents by reducing the thickness of the mattress (4) and maintaining from this reduction in thickness to step d) of cooling. 12 - Method according to one of claims 10 or 1 1, characterized in that, between the steps b) of carding and c) heating, is integrated a step of applying at least one outer layer of reinforcement ( 10) on at least one of the faces of the mattress (4).

13 - Process according to any one of claims 10 or 12, characterized in that, between the steps of b) carding and c) heating, is integrated a hydraulic or mechanical needling step.