Method of processing silicone wastes
A method of processing polymer materials, highly filled or otherwise to recover cyclic structures or monomers. The method involves providing a vessel having a heated side wall, an agitator, and at least one of an additional heated structure, other than the heated side wall, within the vessel and means for forming a thin coat of material processed in the vessel on said heated side wall. A polymer material is fed into the vessel and heated to a sufficient temperature to cause depolymerization of the polymer material into cyclic structures or monomers. The cyclic structures or monomers are removed from the vessel and collected. The method does not require the use of a solvent.
1. A method of depolymerizing silicone materials, highly filled or otherwise which comprises:
providing a vessel having an inlet and an outlet, a heated side wall, an agitator which is internally heated by a fluid media and which mixes and transports materials though the vessel between the inlet and outlet;
feeding a silicone material into the vessel as at least one of,
unprocessed silicone materials, or
pre-digested silicone materials together in a neutralized pre-digestion reaction mixture;
heating the silicone material in the vessel to a sufficient temperature to cause depolymerization of the silicone material into oligomers that are in a vapor phase;
removing the oligomers from the vessel as vapors; and
collecting and condensing the oligomer vapors.
2. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the vessel comprises a thermal auger or a thermal screw.
3. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 2 , wherein the additional heated structure comprises paddles the thermal auger.
4. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 3 , wherein the paddles of the thermal auger are configured to have a clearance with respect to the heated side wall of the vessel which is sufficient to spread a thin coat of material processed in the vessel on said heated side wall which thin coat of material is sufficiently thin to enhance the transfer of heat from the side wall of the vessel into the material processed in the vessel.
5. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 3 , wherein the silicone material comprises silicone waste material.
6. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , further comprising providing a silanolate catalyst in the vessel with the silicone material.
7. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 6 , wherein the silanolate catalyst is formed by the addition of an alkali metal to both ends of a cyclic oligomer in the process of a ring-opening reaction and is formed in the vessel or formed prior to being introduced into the vessel.
8. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the pre-digested silicone material is pre-digested using an acid followed by neutralization to allow for efficient basic catalysis and depolymerization.
9. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the oligomers are collected under vacuum.
10. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the silicone material is fed into the vessel without any solvent being present.
11. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the silicone materials comprise at least one of a silicone fluid, a silicone emulsion, a silicone sealant, a silicone rubber, a silicone gum, silicone tubing, a silicone band and a silicone glove.
12. A method of depolymerizing silicone materials, highly filled or otherwise according to claim 1 , wherein the depolymerization process is conducted until a substantially dry powder residue is produced in the vessel.