WO2008049980A1

WO2008049980A1 - Composite reinforcement for impregnation or coating

Info

Publication number: WO2008049980A1
Application number: PCT/FR2006/051124
Authority: WO
Inventors: Jérôme VILLE
Original assignee: Fibroline France
Priority date: 2006-10-27
Filing date: 2006-10-27
Publication date: 2008-05-02

Abstract

The invention relates to a composite reinforcement comprising one or more filamentary or fibrous sheets intended to be impregnated or coated with a layer of organic material. At least one of the aforementioned sheets includes pockets of organic bonding resin (201, 202) made from a preferably thermosetting polymer material, at least 50 vol.-% of said pockets being located at the intersections between the fibres.

Description

COMPOSITE REINFORCEMENT FOR IMPREGNATION OR COATING

TECHNICAL AREA

The present invention relates to a composite reinforcement comprising at least one consolidated sheet of fibers and intended to be impregnated or coated with an organic material. Such composite reinforcement may for example be impregnated with a layer of bitumen so as to provide a coating for sealing a terrace or a roof, in particular a flat roof not covered with tiles.

PRIOR STATE OF THE ART

To waterproof a roof or terrace, bitumens are used because of their high resistance to penetration of moisture, that is to say for their impermeability, and because of their high ability to impregnate and adhere to the support on which they are spread. Sealants are herein referred to as bituminous coatings. These coatings are usually stored and transported in the form of standard width rolls that are unwrapped on demand at the installation site.

Deformation of bitumens subjected to shear stress is relatively slow and continuous. In addition to this mechanical stability, the bitumens have good chemical and physical stability, low sensitivity to temperature variations and a high point of flammability of the vapors.

To make a bituminous coating, it is generally used a composite reinforcement that is impregnated to make it waterproof. Most often, such reinforcements are composed of woven fabrics or non-woven mats made of glass fibers and / or synthetic fibers and possibly associated with reinforcing grids. In particular for the applications mentioned above, the reinforcements constituting these bituminous coatings must have the following mechanical properties:

• high tensile strength;

• a high initial modulus of elasticity; • resistance to perforation and shear or high tearing;

• a specific stiffness in bending to facilitate the installation of the reinforcement;

• Dimensional stability during use of the product and during its manufacture.

The specific rigidity sought is in fact that which makes it possible to prevent the formation of folds when the reinforcement is impregnated with the organic material, in particular to prevent the formation of air bubbles, for example during an impregnation of bitumen.

To obtain these mechanical properties, such coatings consist of textile reinforcements which may be monolayer structures or multilayer structures. In the latter case, it is possible, for example, to associate nonwovens with reinforcing grids generally made of glass fibers. In general, the nonwovens incorporated in such structures are made of polyester generally manufactured by a direct extrusion technology by melt (in English "spun" or "spunbond"), making it possible to obtain a nonwoven from continuous filaments . In known manner, the fibers are short and discontinuous while the filaments are long and continuous.

In order to produce composite reinforcements with a monolayer structure, as for reinforcements with a multilayer or complex structure, in the known manner, non-woven fabrics of the "spun" type undergo a needling or calendering operation which gives them a certain mechanical cohesion. Then they are chemically bound by means of a binder resin, in order to increase their rigidity and to give them the desired consistency before impregnation with bitumen. Composite reinforcements are thus obtained which are to be impregnated or coated with organic resins. In the methods of manufacturing the composite reinforcements of the prior art, the chemical binders are applied wet. Thus, these chemical binders are generally applied to the aqueous reinforcement in the form of a latex emulsion; the proportion of binder resin on the total mass of the composite reinforcement generally varies between 15% and 30%. The resins may be vinyl-acrylic, styrene-acrylic, melamine, urea, etc.

If such composite reinforcements of the prior art generally have the desired mechanical properties, the aqueous manufacturing process requires additional operations related in particular to the preparation of the latex solution and the evaporation of water.

In addition, the mass of liquid resin required should preferably be greater than 15% of the mass of the final composite reinforcement. Thus, in view of this minimum mass, the fibers of the woven fabric or the nonwoven fabric are homogeneously coated, since the resin is used in aqueous form. The resin is thus placed partly in places where it is of no use.

In addition, to manufacture multilayer reinforcements, the processes of the prior art often require an additional operation of needling or water jet bonding prior to impregnation with the binder resin.

The objective of the present invention is therefore to provide a composite reinforcement relatively simple to manufacture, having mechanical properties in adequacy with its end use, and whose weight remains limited. In the reinforcing object of the invention, the mass of binder material is not homogeneously distributed over the fibers. SUMMARY OF THE INVENTION

The present invention relates to a composite reinforcement whose mass of binder material is distributed heterogeneously on the fibers. The reinforcement which is the subject of the invention has good thermal stability, rigidity or an optimal "hand", good mechanical strengths and good wettability for subsequent impregnation and / or coating, for a production cost and a weight. relatively low end product.

According to the present invention, the composite reinforcement comprising one or more fibrous (s) or filamentary web (s) intended to be impregnated or coated with a layer of organic material is characterized in that at least one of these webs include binder organic resin clusters in powder form, at least 50% by volume of these clusters being located at intersections between the fibers.

In other words, the binder organic resin is distributed heterogeneously in a fiber web and it is housed mainly on or near crosses between fibers. Thus, this resin fully plays its role of bonding the fibers together. Conversely, only a small amount of the binder resin is distributed over the portions of the fibers that are not in contact with any other fiber. By intersection, we designate a region where two or more fibers are very close or come into contact with each other, without obviously "cutting" in the proper sense. In addition, the binder organic resin thus distributed can be used to bind together several different materials to make multilayer reinforcements without needling operation or water jet binding. The present invention also makes it possible to reinforce multilayer products that have been previously assembled by needling. The object of the invention therefore has a good ratio between resin mass and mechanical strength, thereby further reducing the total mass and the cost of the composite reinforcement.

Advantageously, at least 70% by volume of the clusters can be located at intersections between the fibers. In practice, the binder organic resin may represent between 3% and 40% of the mass of the composite reinforcement, preferably between 5% and 20%. The mass of the composite reinforcement here designates the mass of the fiber web plus the mass of the binder resin.

Thus, the composite reinforcement object of the invention has a weight and a cost price even lower than the mass proportion of binder resin used is low. Notwithstanding its relatively low content of binder resin, the composite reinforcement object of the invention is able to fulfill the mechanical, thermal and chemical functions sought.

According to a particular embodiment of the invention, the sheet may be composed of materials selected from the group consisting of synthetic materials such as polyesters, polyolefins, polyamides, aramids, or in the group comprising natural materials such as jute, linen or among the mineral materials glass, basalt, ceramic.

A good part of these materials have a thermal stability which allows the impregnation and / or coating of the composite reinforcement by a layer of material brought to a temperature typically greater than 200 ^° C. This thermal resistance makes it possible, in particular, to use such a reinforcement for impregnation with bitumen. The other materials also allow impregnation or coating of the reinforcement, but with organic materials used at lower temperatures.

Conveniently, the web may be associated with a mat of continuous or cut glass fibers or a fiberglass grid.

The addition of such a grid to the web provides a composite reinforcement mechanically more resistant and having a better dimensional stability. According to another particular embodiment of the invention, the binder organic resin may be composed of thermosetting materials chosen from the group comprising polyepoxides, mixtures of polyepoxides and polyesters, acrylics, compounds based on melamines, compounds based on urea-formaldehyde, phenolic compounds, or thermoplastic materials such as a polyester cyclic oligomer (CBT).

Since these different materials are thermally relatively stable, they can serve as binders for producing composite reinforcements intended to receive impregnation and / or induction at a high temperature, and typically greater than 200 ^° C.

Moreover, the method of manufacturing a composite reinforcement comprising a sheet of fibers intended to be impregnated or coated with a layer of organic material. According to the invention, this method comprises the steps of:

- sprinkling particles of a binder organic resin powder on the web in a proportion representing between 3% and 40% of the mass of the composite reinforcement, preferably between 5% and 20%;

- Subjecting the web and sprinkled to at least one electric field, so as to move the particles within the web;

- To heat the assembly thus formed beyond the softening temperature of the binder resin.

In other words, the displacement and positioning of the binder resin powder particles within the fiber sheet are achieved by means of forces generated by an electric field. This step makes it possible to manufacture the composite reinforcement as explained above. In particular, the heating step makes it possible to fix the binder resin powder on the sheet of fibers.

In practice, the electric field may have an alternating voltage of frequency between 2 Hz and 500 Hz and an amplitude of between 100 kV / m and 80000 kV / m.

Such an electric field makes it possible to efficiently move the powder particles within the sheet. Indeed, an alternating field causes displacements oscillation of the powder particles, which therefore move to be held in position, which is the case in particular when they are agglutinated at the intersection of several fibers.

Also conveniently, the electric field can be generated between globally flat electrodes and parallel to each other.

Alternatively, the electric field can be generated between globally tubular electrodes.

Such geometries of electrodes make it possible to generate an electric field capable of moving the powder throughout the layer of fibers constituting the reinforcement.

Advantageously, the powder may have a particle size whose maximum diameter is essentially less than 300 microns, preferably less than 100 microns.

This relatively fine particle size therefore characterizes a very mobile powder and which will not tend to stagnate in the open regions between fibers. In addition, it is possible to implement fine powders constituting by-products of certain industries, such as paints, which makes it possible to recycle these by-products otherwise unusable and thus to reduce the cost of the composite reinforcement. Maximum diameter refers to the diameter above which there is a negligible fraction of particles.

BRIEF DESCRIPTION OF THE FIGURES

The manner in which the invention can be realized and the advantages which result therefrom will also emerge from the following example embodiment. This example is given for information only and is not restrictive, in support of the appended figures among which:

Figure 1 is a reproduction of a microscope photograph of a sample of a composite reinforcement of the prior art.

Figure 2 is a reproduction of a microscope photograph of a sample of a composite reinforcement according to the present invention. MODE OF REALIZATION

While FIG. 1 illustrates a reinforcement of the prior art, FIG. 2 illustrates a photograph taken under a microscope of a sample of a composite reinforcement according to the invention. This figure is shown off scale, but it nevertheless allows to visualize the main characteristic of the composite reinforcement object of the present invention, namely the agglomeration of the binder resin at the intersections between fibers.

The visual comparison between these two photographs thus makes it possible to observe that the reinforcing object of the invention comprises more binder resin 201, 202 at the intersections between fibers. Conversely, it is found that the fibers of the reinforcement of FIG. 1 are covered with binder resin relatively uniformly. This uniform distribution therefore implies the use of a large mass of resin to impart the desired mechanical properties to the reinforcement.

The reinforcement of FIG. 2 was obtained by operating the method which is the subject of the invention. The mass proportion (thus volume, assuming that the variation in the density of the resin is low or zero) is here 18%. The fiber / powder unit was previously subjected to an alternating voltage electric field and then heated to 21O ⁰ C. The electric field can be implemented with characteristics similar to those described in EP-AI 028 836 or EP-A1 526 214.

Therefore, the present invention minimizes the amount of binder resin to be used to achieve maximum mechanical performance. Indeed, the binder resin is located mainly in the regions where it is likely to play its role, while the binding of the wet fiber webs, as explained above, produces a relatively homogeneous coating of the fibers, thus inducing the presence of binder resin in areas where it has little or no use. In addition, the mechanical strength is also increased due to the implementation of a "rigid" resin having good chemical compatibility with the fibrous support. In addition, it may have good compatibility with organic materials used for coating or impregnation, such as bitumen.

In addition, the mass proportion of binder resin powder being low, the cost price of the composite reinforcement is therefore reduced.

Another advantage of the method that is the subject of the present invention is that it implements the binder resin in powder form. Thus, it is possible to use any type of thermosetting powder, including a relatively fine powder, to carry out the process which is the subject of the invention.

There are several sources of supply in the industry at very low cost for such powders, namely the paint and varnish industry. Indeed, these industries produce relatively high amounts of unusable powder, either because they are too fine, or because one shade is polluted by another shade. Consequently, the method of the invention makes it possible to reuse these powders to manufacture composite reinforcements in accordance with the invention and economic.

However, powder paints have the qualities necessary for their use in the field of composite reinforcements, namely:

• good fluidity during the first thermal cycle and before gelation;

A fine particle size, typically less than 200 μm or even 100 μm, which makes it possible to obtain an optimum distribution of the powder particles in the fiber sheet;

• a chemical affinity compatible with that of the fiber web used;

• a very low cost.

The composite reinforcement object of the present invention thus has a thermal stability, a mechanical stability and a chemical stability which make it quite adapted to be impregnated or coated for example with bitumen to make waterproof roofs or other organic materials. Moreover, its cost is quite competitive. Finally, its weight and rigidity make it easily transportable, storable and suitable for processing by coating or impregnation. This composite reinforcement may also be associated, in particular by bonding with the binder resin, to other layers made of different materials, such as a plastic film or a metal foil.

Other embodiments of the invention and other applications are possible, without departing from the scope of this invention. For example, it is possible to use a reinforcement according to the invention for producing floor coverings and wall coverings, etc.

Claims

Composite reinforcement comprising one or more fibrous or filamentary plies intended to be impregnated or coated with a layer of organic material, characterized in that at least one of said plies includes binder organic resin clusters in powder form, at least 50% by volume of said clusters being located at intersections between said fibers.

2. Composite reinforcement according to one of the preceding claims, characterized in that said binder organic resin is between 3% and 40% of the mass of said composite reinforcement, preferably between 5% and 20%.

3. composite reinforcement according to one of the preceding claims, characterized in that said sheet is composed of materials selected from the group consisting of synthetic materials such as polyesters, polyolefins, polyamides, aramids, or in the group comprising natural materials such as as jute, linen or among the mineral materials glass, basalt, ceramic.

4. composite reinforcement according to one of the preceding claims, characterized in that said web is associated with a mat of continuous or cut glass fibers or a glass fiber grid.

5. composite reinforcement according to one of the preceding claims, characterized in that said binder organic resin is composed of thermosetting materials selected from the group comprising polyepoxides, mixtures of polyepoxides and polyesters, acrylics, melamine-based compounds compounds based on urea-formaldehyde, phenolic compounds, or thermoplastic materials such as a polyester cyclic oligomer (CBT).

6. A method of manufacturing a composite reinforcement comprising one or more fibrous or filamentary webs intended to be impregnated or coated with a layer of organic material, characterized in that it comprises the steps of - sprinkling particles of a binder organic resin powder on at least one of said plies in a proportion representing between 3% and 40% of the mass of said reinforcement, preferably between 5% and 20%; - Subjecting said web thus sprinkled to at least one electric field, so as to move said particles within said web; - To heat the assembly thus formed beyond the softening temperature of said binder organic resin.

7. Method according to claim 6, characterized in that said electric field has an AC voltage of frequency between 2 Hz and 500 Hz and an amplitude of between 100 kV / m and 80000 kV / m.

8. Method according to one of claims 6 to 7, characterized in that said electric field is generated between globally flat electrodes and parallel to each other.

9. Method according to one of claims 6 to 7, characterized in that said electric field is generated between globally tubular electrodes.

10. Method according to one of claims 6 to 9, characterized in that said powder has a particle size whose maximum diameter is substantially less than 300 microns, preferably less than 100 microns.