Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Patent
1997-06-12
1998-06-30
Warden, Jill
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
134 10, 134 42, 65473, 209 3, B08B 704
Patent
active
057727775
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of a PCT/FR/01671, filed on Dec. 14, 1995.
BACKGROUND OF THE INVENTION
The present invention relates to a process for the treatment of composite materials, comprising a matrix and reinforcing fibers, for the purpose of recycling said materials.
Said process is particularly valuable insofar as it is useful for the upgrading of materials. The process in fact enables the fibers to be separated from the matrix and recovered in a state such that they can be recycled as reinforcing fibers.
The question of recycling waste of the composite material type, especially thermosetting and thermoplastic materials, only really arose very recently. The custom was in fact to dump this kind of waste in landfills, which was very practical and economically advantageous.
Now, for some years, especially due to ecological pressure, the number of landfills has been gradually falling and their absorption capacity decreasing. The cost of dumping in landfills is rocketing. Furthermore, the imminent implementation of very strict national and/or Community regulations will limit landfill dumping to non-recyclable waste.
It has therefore become essential to develop processes for the treatment of these composite materials, especially in order to recycle them.
Researches have been conducted in several directions and three principal methods of upgrading said composite materials have been proposed: energy. However, this method is rather unsuitable for composite waste insofar as it has a relatively low calorific value. In fact, the mineral fillers in the matrix, and the reinforcing fibers, which are inert to combustion, can represent up to 70% by weight of said materials. Moreover, the incineration of such materials ultimately produces a large amount of dross. This mechanical method is particularly valuable insofar as it makes it possible to recover on the one hand the fibers and on the other hand a powder (binder+fillers), which are respectively recyclable as reinforcing fibers and fillers in the production of new composite materials. It is illustrated especially in patent application EP-A-0 443 051. However, this method cannot be used to treat waste contaminated particularly by oils, adhesives, paints, etc. types of process. In a first variant, said materials are thermally decomposed in the total absence of oxygen (pyrolysis). This seems to be the perfect process for treating contaminated waste. It allows the recovery of organic products (petroleum products), gas of high energy value and an inorganic solid residue (containing the fibers) which can be recycled as fillers in the production of new composite materials. However, it does not allow the fibers to be recovered and recycled as reinforcing fibers. In a second variant, said materials are chemically degraded by hydrogenation, hydrolysis, glycolysis, etc. This variant has given very good results in the glycolysis of polyurethane resins reinforced with glass fibers. The chemical treatment ultimately produces on the one hand polyols, which can be used in the formulation of polyurethane resins (for the production of new composite materials), and glass fibers (virtually intact), which can be used as reinforcing fibers.
Other chemical methods have also been exploited for the upgrading of non-reinforced polymers (not containing fibers) and especially for the recycling of said polymers as texturizers for hydrocarbon binders of the bitumen type. The following have been described in particular: (polyethylene) in order to activate said polyolefin and thereby render it compatible with the bitumen; conditions in order to decrosslink crosslinked polymers based on ethylene/vinyl acetate (EVA).
According to the teaching of these documents, ozone is capable of causing crosslinked polymer materials to decrosslink into polymer fragments whose molecular weight is less than that of said crosslinked polymer materials, and of generating reactive groups (peroxides, hydroperoxides) on the surface of said fragments.
SUMMARY OF THE INVENTION
According to the invention, a process fo
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Delmas Michel
Fargere Thierry
Sacher Gilles
Vallet Andre
Chaudhry Saeed
Societe Europeenne de Propulsion
Warden Jill
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