WO1998036114A1 - Process for recycling textile floor and wall coverings and fibrous tablecloths obtained using this process - Google Patents

Abstract

Disclosed is a recycling process for complex textile structures, such as floor or wall coverings, consisting in: selectively sorting the materials to be recycled so as to obtain a homogenous mixture of the materials to be processed; filamentation of said materials to form a mixture of fibers of varying lengths. During this filamentation process, the non-fibrous components constituting a portion of the base structure can be eliminated; incorporation into the fiborus mixture of any additives that may be required to manufacture the final product; formation of a lap from the fibrous mixture obained; heat treatment of the newly formed lap in order to fuse a portion of the fibrous constituents of the mixture or to polymerize an additive, this heat treatment being performed by placing the lap between two conveyors permeable to air, inside a chamber subjected to a hot inflow; cooling of the newly formed lap.

Description

PROCESS FOR RECYCLING FLOOR OR WALL COVERINGS

DARK TEXTILES AND TABLECLOTHS OBTAINED BY THE IMPLEMENTATION

WORK OF THIS PROCESS.

Technical area

The present invention relates to an improved process for recycling complex textile structures such as in particular floor coverings or wall coverings which, given their composition, are practically not recycled at present and are purely landfilled, which further the costs of such disposal pose problems for environmental protection.

In the following description, the invention will be described for the recycling of carpets, rugs, wall coverings, etc., but it is obvious that such a process can be used to recycle any type of equivalent material.

Previous techniques

To date, this type of waste has two main sources, namely on the one hand the waste obtained during the actual production of the articles, such as for example scraps, selvedges and / or the production of products out of specification which are not marketable as well as waste articles used consisting either of single-use products (coatings for salons; exhibitions ...) or after normal wear and tear.

The difficulty in recycling such products stems from the complexity of their composition.

Indeed :

^" They can be made from natural fibers (wool, silk, etc.) or synthetic yarns or filaments (polyamide 6 or 6.6, polypropylene, etc.);

^~ They can include one or more supports of natural fibers (jute ..) or synthetic fibers or films in which the fibrous structure of appearance is established for example by "tufting" or other equivalent technique, the surface condition of the products can be either in the form of loops or in the form of hair and; they may comprise a layer of latex intended to reinforce the bond between the threads or filaments and the support fabric, optionally a filler of calcium carbonate and / or a foam undercoat.

In general, such products therefore consist of mixtures of materials having different chemical and physical characteristics and at least one of which, for example the base ply serving as a support, is based on a synthetic material (polypropylene for example ), whose melting and / or softening temperature is lower than the temperature necessary to cause a modification of the structure and properties of the other constituents.

Other products of simpler design may consist of a simple needle felt which is impregnated with resin or latex.

To date, the solutions envisaged for ensuring the recovery and recycling of the constituents of such products consist in carrying out a separation and recovery of the different types of constituents, as is shown in particular from the publication RD-388013 filed on July 20, 1996 and updated available to the public on October 10, 1996 and which was listed in the Derwent database under the reference 96-400073 (40) as well as EP-A-0 515 946.

According to the teachings of this last document, recovery and recycling is carried out, in particular of floor coverings, by cutting the material into small pieces then by carrying out a suspension of the material in water so as to make a "pulp" which, after filtration and drying, makes it possible to separate the fibers from plastic granules, the components thus obtained being then reused.

Such separation into elementary constituents is difficult to implement and entails significant production costs. Furthermore, the reuse of the synthetic components thus separated (Nylon and polypropylene for example), involves subsequent processing operations. Statement of the invention

However, we have found, and this is what is the subject of the present invention, a simple, economical process which makes it possible to obtain directly at the end of the recycling cycle non-woven products, the density of which can be adjusted in depending on their application and which can be used in many technical sectors such as for example:

• acoustic, mechanical and thermal insulation felts (cars, constructions, carpet underlayments, furniture, household appliances, etc.) and;

• sound and thermal insulation (building, etc.).

In general, the method according to the invention making it possible to recycle complex textile structures, consists in: carrying out a selective sorting of the materials to be recycled so as to have a homogeneous overall composition of materials to be treated; ^" to carry out a defibration of said materials so as to form a mixture of fibers of variable length, the non-fibrous components entering the basic structure being able to be eliminated during this defibration operation; to optionally incorporate inside said fibrous mixture additives depending on the final product to be produced; ^" to form the fibrous mixture obtained in the form of a sheet and;

^" to heat treat the sheet thus formed so as to cause the melting of a portion of the fibrous constituents entering the mixture or the polymerization of an additive, this heat treatment being carried out by passing the sheet between two conveyors, permeable to the air, inside an enclosure subjected to a current of hot air; to cool the sheet formed.

In accordance with the invention, recycling is carried out by means of conventional equipment for the recovery of textile waste, such as cutters, shredders, "Pickers", openers, frayers, part of the non-fibrous components which can be eliminated during this process. surgery. Preferably, during this operation, a large amount of waste is mixed in order to obtain better homogeneity of the products. The formation of a sheet from the fibrous mixture is advantageously carried out by means of volumetric chimneys and / or pneumatic tablecloths, which by design allow the integration of short fibers, powders and small solids in the sheet.

During this tableting operation, or prior to this, a component (fibers, powders, etc.) having a solid / pasty / liquid transformation or polymerization temperature below that of the defibrated product is added if necessary. of the majority of the fiber mixture. This allows, when the resulting product is brought to a temperature slightly exceeding the aforementioned temperature, to melt or polymerize this component, which, after cooling or by polymerizing, creates points of mechanical connection between the fibers and other parts of the defibrated product. .

It can also be envisaged to add components to the defibrated product which can give the final product particular characteristics such as, for example: antibacterial treatment if the heat treatment of the preceding stage does not make it possible to ensure it;

^" non-fire treatment according to the standards for use of the final product; possibly, such treatment may be superfluous depending on the original qualities of the fibers.

The mixing of the additives (binders, etc.) is carried out either before the formation of the sheet, for example in the case of addition of additional fibers, treatment by spraying powders or sprinkles or immersion in a liquid solution, or during the formation of said sheet (dispersion of powders, etc.), or even by spraying onto the sheet after its formation, and this by any known process used in the production of nonwoven products.

The most important step of the process according to the invention lies in the way in which the heat treatment and the cooling are carried out, making it possible to ensure the consolidation of the structure.

This heat treatment is carried out by passing the fibrous web between two conveyor belts thereby giving it the desired density in depending on their spacing, the rise in temperature to cause the revelation of the binding properties of part of the fibers or of the additives being obtained by means of a current of hot air which passes through the sheet perpendicular to its thickness.

If the binder component that the mixture comprises is a thermosetting component, the density of the sheet obtained is determined during the heating operation by the spacing of the conveyor belts inside the oven.

On the other hand, if the binder component is based on a thermoplastic material, or if the composition of the starting product allows it, the sheet is also heated between two conveyor belts, the cooling step which follows the heating operation being also carried out between two conveyor belts by means of a flow of cold air perpendicular to said belt.

By proceeding in this way, it is possible to obtain fibrous webs of different density which can be used in different applications.

Way of realizing the invention

The invention and the advantages which it brings will however be better understood thanks to the two concrete examples of embodiment given below for information but not limitation:

^~ The first relating to the production of a sound insulation felt, mechanical, thermal, usable in the automotive sector, in construction, as an underlay of carpet for furniture, household appliances;

^~ the second relating to the production of a sound insulation felt, thermal, of low density, usable in the construction sector.

The concrete examples given below are carried out on a conventional processing line for the recycling of fibrous waste, which comprises in the order of production:

^" a bale cutter assembly of textile materials for regular feeding of the following machine; a rotary cutter cutting said raw material;

^" a shredder;

^" a mixing silo ensuring a reserve and allowing a mixing of the materials to have a good homogeneity of the final product; ^" a set of loaders allowing to incorporate possibly binding materials in the mixture of shredded materials; at least one opener which homogenizes the mixture of fibers and distributes the binding materials very homogeneously inside said fibers;

^~ a pneumatic tablecloth giving a regular tablecloth whose weight per square meter is adjustable.

As a type of material, conventional machines offered by the Applicant can be used.

At the outlet of the conformation assembly in the form of a sheet, is arranged the essential element for the proper implementation of the method according to the invention, namely a heat treatment chamber constituted by an oven inside which circulates a current of hot air which crosses the sheet in the direction of its thickness, the sheet of fibers formed being conveyed inside said oven between two conveyor belts, permeable to air, whose spacing and speed are regulated depending on the thickness and density that you want to give to the final product. This heat treatment zone is followed by a cooling zone which, preferably, also consists of two conveyor belts, also permeable to air, the cooling being obtained by a circulation of cold air also passing through the sheet in the sense of its thickness.

A production technique makes it possible to produce sheets, the connection of which can be obtained both from a thermosetting component and from a thermoplastic component.

On leaving the installation, the sheet formed can be received either in the form of a roll, or possibly cut into panels of predetermined length. Example 1

On a production line as described above, a mixture of carpet waste is supplied comprising a basic support consisting of a polypropylene fabric in which polyamide threads are implanted by "tufting", the back of which has received a coating of latex and which is covered with an underlay consisting of foam.

This waste is fed into a production line which provides defibration, fraying, mixing of the constituents. Part of the products constituting the back coating and the foam underlay is automatically eliminated during these operations.

The fibrous mass obtained, which optionally comprises residual filler and foam particles, is shaped in the form of a sheet weighing 1000 grams / square meter.

Optionally, polypropylene fibers are incorporated into the fibrous mixture so that the sheet comprises approximately 20% of such fibers. This layer is introduced inside a heat treatment and cooling assembly which ensures its densification and the connection.

When the web runs inside the oven, a circulation of hot air at a temperature of around 200 ° C. is created, which, taking into account the speed of passage of the material, makes it possible to obtain a temperature rise of the fibers to around 150-160 ° C, resulting in the melting of the polypropylene-based constituents and the bond with the other components. In the cooling zone which follows the heating zone, the sheet is also held between two conveyor belts, the space of which is adjusted to 5 mm. The cooling is ensured by a circulation of cold air which crosses the sheet in all its thickness.

At the outlet of the production line, a structure is obtained which is in the form of a sheet having a density of 100 ranges / dm3 and a thickness of 1 cm.

Such a tablecloth can for example be used to make carpet underlayers. Example 2

Example 1 is repeated except that binder fibers constituted by polyester / polyethylene bicomponent fibers are incorporated into the fibrous mixture, and this at a rate of 20% by weight relative to the starting weight of the sheet which , in the case of this example, is 1200 g / m2.

As before, the sheet is treated inside a heat treatment and cooling assembly which makes it possible to ensure its densification and the connection.

During heat treatment and cooling treatment, the space between the conveyor belts is set to 50 mm. The temperature inside the oven is 170 ° C., which allows the fibers to be brought to a temperature of the order of 140 ° C.

After cooling, a sheet having a thickness of 50 mm having a density of 23 g / dm 3, which can be used as sound insulation material in the building or other similar fields, is obtained.

The foregoing examples clearly show all the advantages provided by the invention, and in particular the fact that it is possible to recycle floor coverings or the like in a simple, economical manner and to obtain, directly at the end of this operation. recycling, reusable fibrous webs for many applications.

In addition, very homogeneous bonding materials are obtained, being obtained by melting part of the constituents being distributed over the entire thickness.

Of course, the invention is not limited to the examples described above, but it covers all the variants produced in the same spirit.

Claims

1 / A process for recycling complex textile structures, such as floor or wall coverings, which consists in: carrying out a selective sorting of the materials to be recycled so as to have a homogeneous overall composition of materials to be treated; defibering said materials so as to form a mixture of fibers of variable length, the non-fibrous components entering the basic structure being able to be eliminated during this defibration operation; optionally incorporating into said fibrous mixture additives according to the final product to be produced; to conform in the form of a sheet the fibrous mixture obtained and; heat treating the sheet thus formed so as to cause the melting of a portion of the fibrous constituents entering the mixture or the polymerization of an additive, this heat treatment being carried out by passing the sheet between two conveyors, permeable to air, inside an enclosure subjected to a current of hot air; to cool the formed web. 2 / A method according to claim 1, characterized in that the cooling of the sheet after heat treatment is carried out by passing between two conveyor belts subjected to a stream of cold air which pass through the sheet in the direction of its thickness. 3 / A method according to claims 1 and 2, characterized in that the formation of the sheet from the fibrous mixture is carried out by means of volumetric chimneys and or pneumatic lappers. 4 / Method according to one of claims 1 and 3, characterized in that during the forming of sheets or prior to the latter, a component having a solid / pasty / liquid transformation temperature or of less polymerization than most of the fiber mix. 5 / Method according to one of claims 1 to 4, characterized in that one adds to the defibrated product additives intended to give it specific characteristics. 6 / A method according to claim 5, characterized in that the additives make it possible to carry out an antibacterial treatment of the fibrous mixture. The method according to claim 5, characterized in that the additives impart non-fire properties to the web. 8 / fibrous web obtained by the implementation of the method according to one of claims 1 to 6, characterized in that the bonding of the fibers between them is obtained by fusion of a minority part of the fibers entering into its constitution.