Machine and process for washing scraps of fibrous material which have been impregnated with resin

Abstract: The invention concerns a machine that can be used for washing scraps of fibrous materials, such as fibreglass, carbon fibre, polyamide, or the like, which have been impregnated with resin, for allowing the extraction of the resin with the use of the appropriate solvents. The machine comprises a closed, hollow container (1) having one inlet (100) and one outlet (200), the container (1) enclosing at least one conveyor belt (5,6,7) over which is situated at least one overhead spraying means (8,9,10) which delivers solvent contained in at least one tank (3,4), wherein a drying means (11) is installed at the end of a conveyer belt (7) upstream the outlet (200). The invention also concerns a process for washing scraps of fibrous material impregnated with resin, comprising the steps of feeding the scraps in a closed hollow container (1), washing the scraps with at least one solvent spray and finally drying the washed scraps inside the container (1).

Description: The present invention concerns a machine that can be used for washing scraps of fibrous materials, such as fibreglass, carbon fibre, polyamide, or the like, which have been impregnated with resin, for allowing the extraction of the resin with the use of the appropriate solvents. This invention can be used in those industries involved in the manufacture of machinery to be used in industries dealing in the manufacture of components and machines with fibreglass, carbon fibre, polyamide staple or the like, as well as in those activities related to the manufacture of machinery to be used in the recycling of industrial waste. The invention can be suitably designed to ensure the total or partial recycling of the fibreglass, carbon, polyamide or similar scraps impregnated with resin, thus leading to the recovery of a thermostable matrix and/or reinforcements made up of fibreglass, carbon fibre, polyamide staple or the like, and likewise causing the toxic waste generated during the manufacture of components and machines with these materials to be made inert and during the reduction of a thermostable matrix into fibrous materials. The use of fibrous materials as fibreglass, carbon fibre, polyamide, or the like, which have been steeped in resin is common in the manufacture of numerous elements. In one known process, a thermostable matrix is placed on a mold surface and impregnated with resins. The said resins are subsequently hardened, affording rigidity to the whole. The process gives rise to a light product with enough resistance for it to be suitable for various industrial purposes, among which are those concerned with the manufacture of containers capable of holding corrosive liquids. Also quite frequent is the incorporation of reinforcements of fibreglass, carbon fibre, polyamide staple or the like in the thermostable matrix, with an aim to affording sufficient structural rigidity for certain industrial purposes. There exists fibreglass pre-impregnated with resins that facilitates the manufacturing process of components by means of the aforementioned process. The manufacture of elements using fibreglass, carbon fibre, polyamide, or the like, placed on a mold and subsequently impregnated with resin, or using fibreglass pre-impregnated with resin, generates a considerable amount of scrap, due to the need to cut the required shapes from the industrial fibrous sheets, especially fibreglass sheets, which are usually rectangular in shape. The scraps from fibreglass, carbon fibre, polyamide or the like, which have been impregnated with resin, form toxic waste which it is desirable to make inert. On the other hand, the possible separation of the resin from the thermostable matrix would allow the latter to be subsequently re-used and the reinforcements optionally present to be recovered. It is known, e.g. from US-A-4 300 955, to separate the thermostable matrix from the resin it has been impregnated with, by washing with appropriate solvents, thus achieving one of the aforementioned objectives. For ecological reasons and for reasons of economy in the industrial process involved in the manufacture of components with fibreglass, carbon fibre, polyamide or the like pre-steeped in resin, an improved industrial machine which could carry out the aforementioned process is desirable. This object has been achieved by a machine according to claim 1 comprising a closed, hollow container having one inlet and one outlet, the container enclosing at least one conveyor belt over which is situated at least one overhead spraying means which delivers solvent for dissolving the resin, the solvent being contained in at least one tank, wherein a drying means is installed at the end of a conveyor belt upstream the outlet. The scraps are fed at the end of the conveyor belt located at the inlet of the container, the said spraying machine(s) spray(s) solvent on the scrap placed on the belts thus dissolving the resin, and the washed scraps are then dried inside the container to prevent any flow of solvent vapour out of the container. In a preferred embodiment, the machine includes a plurality of conveyor belts arranged in series over which are situated a plurality of overhead spraying nozzles. The conveyor belts are preferably inclined and drive the belt in the upper direction, in such a way that the upper end of a first conveyor belt feeds the lower end of the downstream conveyor belt. In a most preferred embodiment, the machine includes a first washing section with a first belt section, optionally consisting of a plurality of conveyors arranged in series, situated above a first tank formed by internal walls of the bottom part of the container, and at least a second washing section with a second belt section arranged in series with the first one, optionally consisting of a plurality of conveyors, situated above a second tank formed by internal walls of the bottom part of the container and separated from the first one, an overhead spraying device being located above each of the conveyor belt section. The shape of the container can be suitably designed in various ways; preferably, the shape of the bottom tanks is a parallelepiped. Separation of the resins from the scraps of fibrous materials is achieved by the spray of solvent dissolving the resins, the used solvent being collected and subsequently stored in the tanks preferably placed for that purpose within the container. The flow of solvent from the overhead spray machines is re-circulated from the tanks for that purpose within the container. The tank situated directly under the first conveyor belt section feeds the overhead spray machines that wash the said conveyor belt(s), while the scrap on the second conveyor belt section is washed by means of the solvent supplied by the tank for that purpose situated under the said second section. The possible loss of washing solvent is rectified by means of the addition of clean solvent to the process from a tank connected to the re-circulation circuit by suitable means. In a preferred embodiment, the resin floating in the tank containing the solvent for washing the scrap in the downstream washing section(s) can be periodically transferred to a tank upstream, via an appropriate valve, thus completing the washing process carried out by the overhead spray machines situated over the first conveyor belt section and keeping the washing solvent for the downstream section in optimum condition. At the end of the run of the last conveyor belt there is a drying machine, preferably an air drying machine, which generates a flow of air fed by a suitable compresses air generator. The drying machine is advantageously made up of the necessary pipes and diffusers which circulate a fixed flow of pressurized air over the scrap moving along the conveyor belts. The speed of the process as well as the temperature of the solvents and the nature of the same depend on the characteristics of the said solvents and the properties of the scrap itself. The said variables can be modified by manipulating a control panel of the invention. Also subject-matter of the invention is a process according to claim 10 for washing scraps of fibrous materials impregnated with resin, wherein the scraps are fed in a closed hollow container and washed with at least one solvent spray, thus dissolving the resin, and finally dried within the container. Preferable steps of the process include: circulating the scraps inside the container on at least one conveying belt; collecting the resin-loaded solvent, advantageously under the conveyor belt(s), and re-circulating it to the spraying means; circulating the scraps along a plurality of washing sections each having its own solvent source tank; transferring the resin floating on the surface of the solvent in the solvent tank of a downstream section to the solvent tank of an upstream section; detecting the loss of solvent in the container, in any washing section, and adding clean solvent to set up the solvent quantity to a predetermined value. The machine and process of the invention are capable of separating the thermostable matrix and/or the reinforcements of fibrous scraps including for instance fibreglass, carbon fibre, polyamide or the like impregnated with resin, the toxic waste generated being made inert to a satisfactory degree and the possible subsequent re-use of the thermostable matrix as well as the reinforcements existing in the scraps. Moreover, the machine and process enable the amount of thermostable matrix contained in the final waste from the manufacturing process to be reduced. With an aim to complementing the present description and to helping to understand the characteristics of the invention, the aforementioned descriptive account is accompanied by three sheets of drawings, the aim of which is to illustrate, and in no way do they set down limits. They show the following figures: Figure number 1 shows view from above of a machine according to the invention; Figure number 2 shows a longitudinal section of the machine of figure 1 according a longitudinal plane A-A; Figure number 3 shows a cross section of the machine of figure 1 according to the vertical plane B-B; Figure number 4 shows a cross section according to plane C-C of the machine of figure 1; Figure number 5 shows a longitudinal section according to plane D-D of the machine of figure 1. With the aid of the figures accompanying the present description, one can appreciate that this machine suitable for the use of washing scraps of fibrous materials such as fibreglass, carbon fibre, polyamide, or the like, which have been impregnated with resin, is made up of a closed, hollow container 1 whose cover 20 includes one inlet 100 and one outlet 200. The container houses three conveyor belts 5, 6 and 7 arranged in series, over which are three overhead spray machines 8, 9 and 10 which spray solvent driven by means of pumps 14 and 15 from two tanks created in the container 1 by partitions 2. The conveyor belts are driven by driving means that can be seen on figure 3. The two first conveyor belts 5 and 6 above tank 3 together with spraying means 8 and 9 build up a first washing section, while the third conveyor belt 7 above tank 4 together with spraying means 10 build up a second washing section. A drying machine 11, which generates a flow of air, is situated at the end of conveyor belt 7. It is fed by means of a conventional generator of compressed air. The conveyor belts 5, 6 and 7 are preferably not perforated and incorporate split flaps for dragging. They are made of a material capable of preventing corrosion caused by a continuous dip of solvents like spirits, ketones, or even water at a wide range of temperatures. There are shutting mechanisms 12, 12' and 12" situated at the head of the said conveyor belts 5, 6 and 7 which prevent the solids from being dragged by the flow of washing solvent down to bottom of the container 1. The aforementioned container is preferably made of fire-proof polypropylene. The resin floating on the surface of the second tank 4 in the container 1 is periodically transferred to the tank 3 by means of an appropriate valve, thus ensuring that the solvent from the tank 4 which feeds the spray machine 10 is in optimum condition. Figure 5 reveals the presence of a float 16 in the tank within the container on which the invention rests. The said float regulates the entry of clean solvent from the tank adjacent the container. The loss of solvent, detected by the float 16 and the appropriate electronic circuit control, are rectified by adding clean solvent contained in tank 13, situated adjacent to the container 1 and linked to the spray machine 10 by means of a pipe 18. The invention has the necessary control panel which allows variables such as the speed of the conveyor belts 5, 6 and 7 and the temperature of the solvent to be modified. It is not considered necessary to expand on this description in order for any expert in the field to understand the scope of the invention and the advantages deriving from it. The materials, shape, size and arrangement of the components can be changed whenever it does not imply a change to the scope of the invention as defined in the appended claims. The terms in which this descriptive account has been written should be taken in a broad rather than limiting sense.

Claims: A machine that can be used for washing scraps of fibrous material, such as fibreglass, carbon fibre, polyamide, or the like, which have been impregnated with resin, comprising a closed, hollow container (1) having one inlet (100) and one outlet (200), the container enclosing at least one conveyor belt (5,6,7) over which is situated at least one overhead spraying means (8,9,10) which delivers solvent for dissolving the resin, the solvent being contained in at least one tank (3,4), wherein a drying means (11) is installed at the end of a conveyor belt (7) upstream the outlet (200). A machine according to claim 1, comprising inside the container a plurality of conveyor belts (5,6,7) arranged in series over which are situated a plurality of overhead spraying nozzles (8,9,10). A machine according to claim 1 or 2, wherein at least one solvent tank (3,4) is created by a partition (2) of the bottom part of the container (1). A machine according to any one of the aforementioned claims, wherein at least one conveyor belt (5,6,7) is not perforated and incorporates split flaps for dragging. A machine according to any one of the aforementioned claims, wherein the conveyor belt(s) is(are) made of a material capable of preventing corrosion generated by a continuous dip of solvents like sprits, ketones or even water at a wide range of temperatures. A machine according to any one of the aforementioned claims, wherein closing mechanisms (12,12',12") are situated at the head of the aforementioned conveyor belts (5,6,7) which prevent the solids from being dragged by the flow of washing solvent down to the container (1). A machine according to any one of the aforementioned claims, containing a valve for transferring the resin floating on the surface of the tank (4) within the container (1) to the tank (3). A machine according to any one of the aforementioned claims, wherein the loss of solvent, detected by a float (16) and an appropriate electronic circuit control, is rectified by adding clean solvent contained in a tank (13) which is placed adjacent to the container (1) and connected to the washing device (10) by means of a pipe (18). A machine according to any one of the aforementioned claims, carrying a control panel which allows variables such as the speed of the conveyor belts (5,6,7) and the temperature of the solvent to be modified. A process for washing scraps of fibrous material, such as fibreglass, carbon fibre, polyamide, or the like, which have been impregnated with resin, comprising the steps of feeding the scraps in a closed hollow container, washing the scraps with at least one solvent spray, thus dissolving the resin, and finally drying the washed scraps inside the container. A process according to claim 10, comprising the step of circulating the scraps inside the container on at least one conveying belt. A process according to claim 10 or 11, comprising the step of collecting the resin-loaded solvent and re-circulating as a spray. A process according to any one of claims 10 to 12, comprising the step of circulating the scraps along a plurality of washing sections each having its own solvent source tank. A process according to claim 13, comprising the step of transferring the resin floating on the surface of the solvent in the solvent tank of a downstream section to the solvent tank of an upstream section. A process according to any of claims 10 to 14, comprising the step of detecting the loss of solvent in the container and adding clean solvent to set up the solvent quantity to a predetermined value.

Inventors: GONDRA ZUBIETA KOLDO, PRELLEZO ARRIETA AUGUSTIN, GONDRA ZUBIETA, KOLDO, PRELLEZO ARRIETA, AUGUSTIN
Applicants: SAINT GOBAIN VETROTEX, SAINT-GOBAIN VETROTEX FRANCE S.A.
Application year: 2000
Main classification: B08B3
IPC codes: B08B3