METHOD FOR RECOVERING INORGANIC FIBRES AT ROOM TEMPERATURE IN COMPOSITE MATERIALS OF FIBRE AND RESIN

Abstract

The invention relates to a method by which means inorganic fibres (glass, carbon, aramide, etc.) are recovered from composite materials of fibre and resin, with the significant advantage of working at room temperature. The method comprises the steps of treatment with solvent and separation of the fibre from the residues of degraded resin.

Claims

1. A method for recovering inorganic fibres from a composite material of fibre and resin, characterised in that it is carried out at room temperature and comprises the following steps: a) treatment of the composite material of fibre and resin with a halogenated organic solvent b) separation of the fibre from the resin of the material dissolved in step a).

2. The method according to claim 1, which comprises a step prior to step a) for conditioning and cutting the starting material of fibre and resin.

3. The method according to claim 1, wherein the inorganic fibres are selected from among fibreglass, carbon fibres or aramide fibres.

4. The method according to claim 1, wherein the halogenated organic solvent is a chlorinated organic solvent.

5. The method according to claim 4, wherein the chlorinated organic solvent is selected from among dichloromethane, chloroform, 1,2-dichloroethane, trichloroethylene, chlorobenzene.

6. The method according to claim 1, wherein step a) for treating the composite material of fibre and resin is carried out in a reactor.

7. The method according to claim 1, wherein step a) for treating the composite material of fibre and resin is carried out by stirring.

8. The method according to claim 1, wherein step a) for treating the composite material of fibre and resin is carried out for 15-180 minutes.

9. The method according to claim 1, wherein the halogenated organic solvent is recovered by means of a solvent extraction system and the residual organic solvent is eliminated.

10. The method according to claim 9, wherein the residual organic solvent is eliminated by applying a stream of immiscible gas or liquid in the reactor.

11. The method according to claim 9, wherein the residual organic solvent is eliminated by applying a temperature higher than the boiling temperature of the solvent.

12. The method according to claim 1, wherein step b) for separating the fibre from the resin of the material dissolved in step a) is carried out by means of sifting.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] FIG. 1 shows a diagram of the experimental process that could be used to carry out the method for recovering the inorganic fibres. It shows a solvent tank 1, a reactor 2, a pump 3 for transferring the solvent, a conduit for extracting the solvent from the reactor 4 and a fluid inlet 5.

DETAILED DESCRIPTION OF EMBODIMENTS

[0045] The preferred embodiment of the method described in the present invention is described below. For better comprehension thereof, FIG. 1 is shown.

[0046] To start the method, the solvent tank 1 is filled. This tank is used to store the halogenated organic solvent and has an airtight lid that prevents the solvent from evaporating to the outside.

[0047] The solvent should be a halogenated organic solvent, selected from among dichloromethane, chloroform, chlorobenzene or other solvents with similar characteristics. The choice of one solvent or another can be based on mainly economic criteria.

[0048] The inorganic fibres are made from glass, carbon or aramide. Among these three, the fibre type does not affect the method.

[0049] The nature of resin is important, being able to be used with most resins, except for some with a hot-melt nature that, due to the chemical inertness thereof, are degraded by the halogenated organic solvents.

Prior Step: Conditioning the Composite Material of Fibre and Resin.

[0050] This prior step is optional and during this step, the composite material of fibre and resin is separated from other materials that can be present, such as wood or metal, and cut into fragments according to the dimensions of the reactor 2. The reactor 2 is the vessel wherein the composite material of fibre and resin is treated with the solvent to recover the inorganic fibres. It has a cover that seals hermetically and can be opened or closed to introduce the starting composite material of fibre and resin and remove the recovered fibre following the method. Once the material is cut, it is placed in the reactor 2 to continue with the following steps of the method.

[0051] The fragments will have a larger or smaller size according to the dimensions of the reactor used in step a). Although it is not essential, by way of indication, the fragments can have a size of approximately one-tenth of the diameter of the reactor.

Step a: Treatment of the Composite Material of Fibre and Resin with a Solvent.

[0052] Next, the solvent is pumped from the solvent tank 1 to the reactor 2 where the composite material of fibre and resin is cut. To do so, the pump 3 is used.

[0053] When the halogenated organic solvent (in this case a chlorinated organic solvent is used, specifically 1,2-dichloroethane) comes in contact with the cut material of fibre and resin, the resin and fibre begin to separate. It is recommended to use an agitation system to keep the content of the reactor moving during the treatment. Once the fibres and resin are separated, the agitation system is stopped, if there is one.

[0054] This chemical treatment should be stopped as soon as the resin begins to degrade, without waiting for the resin to dissolve completely. In doing so, the recovered solvent can be subsequently reused in successive steps. The time required usually varies between 15 and 180 minutes, and the optimisation thereof depends on the type of resin treated, the solvent used and the design of the reactor.

[0055] Next, the solvent is extracted from the reactor 2 through the conduit 4, taking it to the solvent tank 1 once again. This extraction can be carried out by gravity, and the conduit 4 should be protected with a particle filter to prevent the degraded resin particles, together with the solvent, from exiting the reactor 2.

[0056] Next, the solvent is eliminated from the fibres by heating the reactor 2 above the boiling point of the solvent (for example, 40 C. for dichloromethane, 61 C. for chloroform, 84 C. for 1,2-dichloroethane, etc.), and air is introduced through the air inlet 5 to carry the evaporated solvent. The solvent eliminated in the drying step can be retained in the filter (for example, of activated carbon, zeolite, silica gel, etc.) before expelling the air current to the outside, or it can be condensed to be reused. As already indicated in the general description, instead of air, water, or another liquid immiscible with the halogenated organic solvent, can also be introduced into the reactor, subsequently separating the solvent and said liquid by decanting. In this case, it would be necessary to subsequently dry the fibres.

Step b: Separation of the Fibres from the Residues of Degraded Resin.

[0057] Lastly, the fibres are extracted from the reactor 2, which are mixed with a large amount of degraded resin particles. The mixture of fibres and resin particles can be separated by means of sifting, subjecting them to vibration in a sieve of a sufficient size so that the fibres do not pass through it, but the particles do. A fluidisation system or any other system suitable for separating solids can also be used.

[0058] The obtained fibres have physical and chemical properties similar to the original fibres, only partially losing the structural order in the case of treating fibres with a specific arrangement.

[0059] This makes it possible for them to be reused in any application in which perfectly arranged fibres are not necessary.