Method for obtaining wax from recycled polyethylene
An economical and environmentally friendly method for producing waxes. In particular, the methods use thermolytic degradation concurrently with a distillation process to obtaining distilled waxes from recycled polyethylene. The resulting waxes have desirable properties, such as reduced molecular weight and narrow polydispersity, that makes the waxes useful in various applications.
1. A process for producing a wax from recycled polyethylene, comprising:
providing an amount of recycled polyethylene;
heating the recycled polyethylene to a high temperature of from about 200 °C. to about 500 °C. and under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute to undergo de-polymerization;
degrading the recycled polyethylene to smaller wax fragments having a molecular weight of from about 200 to about 2,000;
concurrently distilling the recycled polyethylene under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute during the de-polymerization to collect and remove the smaller wax fragments.
2. The process of claim 1 , wherein the recycled polyethylene is selected from the group consisting of high density polyethylene, linear low density polyethylene, and mixtures thereof.
3. The process of claim 1 , wherein the recycled polyethylene is heated to a high temperature of from about 200 to about 500° C.
4. The process of claim 3 , wherein the recycled polyethylene is heated to a high temperature of from about 250 to about 450° C.
5. The process of claim 4 , wherein the recycled polyethylene is heated to a high temperature of from about 350 to about 425° C.
6. The process of claim 1 , wherein the recycled polyethylene has a number average molecular weight of from about 10,000 to about 100,000.
7. The process of claim 6 , wherein the recycled polyethylene has a number average molecular weight of from about 30,000 to about 60,000.
8. The process of claim 1 , wherein the recycled polyethylene has a polydispersity of from about 1.0 to about 2.0.
9. The process of claim 1 , wherein the smaller wax fragments have a molecular weight of from about 300 to about 1000.
10. The process of claim 1 , wherein the smaller wax fragments have a polydispersity of from about 1.01 to about 1.5.
11. The process of claim 1 , wherein from about 60 to about 80 percent of the recycled wax is converted to the smaller wax fragments.
12. A process for producing a wax from recycled
polyethylene, comprising:
providing an amount of recycled polyethylene, wherein the recycled polyethylene has the following general structure
wherein n represents repeating units and further wherein the recycled polyethylene has n from about 250 to about 3500;
heating the recycled polyethylene to a high temperature of from about 200 °C. to about 500 °C. and under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute to undergo de-polymerization;
degrading the recycled polyethylene to smaller polyethylene fragments;
concurrently distilling the recycled polyethylene under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute during the de-polymerization to collect and remove the smaller polyethylene fragments, wherein the recycled polyethylene is converted to the smaller polyethylene fragments having n from about 15 to about 100 in the general structure.
13. A process for producing a wax from polyethylene, comprising:
providing an amount of polyethylene;
heating the polyethylene to a high temperature of from about 200 °C. to about 500 °C. under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute with a vacuum pump to undergo de-polymerization;
stirring the polyethylene during the heating step to degrade the polyethylene to smaller polyethylene fragments having a molecular weight of from about 200 to about 2,000;
concurrently distilling the polyethylene under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute with the vacuum pump during the de-polymerization to collect and remove the smaller polyethylene fragments.
14. The process of claim 13 , wherein the polyethylene is stirred at a speed of from about 100 to about 200 RPM.
15. The process of claim 14 , wherein the polyethylene is stirred at a speed of from about 125 to about 175 RPM.
16. The process of claim 13 , wherein the polyethylene is heated under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute.
17. The process of claim 16 , wherein the polyethylene is heated under a pressure of from about 1 mmHg absolute to about 100 mmHg absolute.