Recycling method for elastomer toughened thermoplastic polymers
Toughened thermoplastic polymers having elastomeric domains in thermoplastic polymer may be recycled by a method comprising dissolving the thermoplastic polymer in a solvent to form a solution, wherein the elastomer is dispersed within the solution as elastomer particulates or droplets, applying a sufficient centrifugal force to the solution to separate the elastomeric particulates or droplets from the solution to form a separated system and (c) recovering the thermoplastic polymer and elastomeric polymer by removing one or both from the separated system. The recovered elastomer and thermoplastic polymer may then be reused in the same type, similar or differing plastics avoiding degradation typically found when recycling toughened thermoplastic polymers.
1 . A method of recycling a toughened thermoplastic polymer having therein an elastomeric polymer that is present as dispersed elastomer domains comprising,
(a) dissolving the thermoplastic polymer of the toughened thermoplastic polymer in a solvent to form a solution, forming elastomeric polymer particles or droplets from the elastomeric polymer and suspending the elastomeric polymer particles or droplets in the solution, wherein there is a density difference of at least about 2% between density of the solution and density of the elastomer particles or droplets in the solution;
(b) applying a centrifugal force to the solution to separate the elastomeric polymer particles or droplets from the solution to form a separated system; and
(c) recovering the thermoplastic polymer and elastomeric polymer by removing one or both from the separated system.
2 . The method of claim 1 , wherein an inorganic particulate that is insoluble in the solvent is added to the thermoplastic polymer, prior to or during the dissolving of the thermoplastic polymer.
3 . The method of claim 2 , wherein the inorganic particulate has an average size that is larger than the elastomer droplets or particulates average size.
4 . The method of claim 3 , wherein the inorganic particulate average size is at least 5 time greater than the elastomer droplets or particulates average size.
5 . The method of claim 1 , wherein the density difference is at least about 5%.
6 . The method of claim 1 , wherein the density of the solution is less than the density of the elastomeric polymer particles or droplets in the solution.
7 . The method of claim 1 , wherein the solvent has a density that is at least 10% lower than density of the thermoplastic polymer.
8 . A method of recycling a toughened thermoplastic polymer having therein an elastomeric polymer that is present as dispersed elastomeric polymer domains comprising:
(a) dissolving thermoplastic polymer of the toughened thermoplastic polymer in a solvent to form a solution, forming elastomeric polymer particles or droplets from the elastomeric polymer and suspending the elastomeric polymer particles or droplets in the solution, wherein there is a density difference between density of the solution and density of the elastomeric polymer particles or droplets;
(b) introducing a second solvent that swells or dissolves the elastomeric particles;
(c) applying a centrifugal force to the solution to separate the elastomeric polymer particles or droplets from the solution to form a separated system; and
(d) recovering the thermoplastic polymer and elastomeric polymer by removing one or both from the separated system.
9 . The method of claim 8 , wherein the second solvent increases the density of said swelled or dissolved particles.
10 . The method of claim 8 , wherein the solvent comprised of a first solvent and the second solvent has a density of at most about 0.9 g/ml.
11 . The method of claim 10 , wherein the second solvent has a density of at least 1.2 g/cc.
12 . The method of claim 10 wherein the second solvent causes the density difference to increase.
13 . The method of claim 11 , wherein the second solvent is a halohydrocarbon.
14 . The method of claim 11 , wherein greater than 0 to about 1.5 wt % of the second solvent is introduced.
15 . The method of claim 8 , wherein an inorganic particulate that is insoluble in the solvent is added to the thermoplastic polymer, prior to or during the dissolving of the thermoplastic polymer.
16 . A method of recycling a toughened thermoplastic polymer having therein an elastomeric polymer that is present as dispersed elastomeric polymer domains comprising:
(a) dissolving thermoplastic polymer of the toughened thermoplastic polymer in a solvent to form a solution, forming elastomeric polymer particles or droplets from the elastomeric polymer and suspending the elastomeric polymer particles or droplets in the solution, wherein there is a density difference between density of the solution and density of the elastomeric polymer particles or droplets, wherein the solvent has a density of at most about 0.9 g/cc;
(b) applying a centrifugal force to the solution to separate the elastomeric polymer particles or droplets from the solution to form a separated system,; and
(c) recovering the thermoplastic polymer and elastomeric polymer by removing one or both from the separated system.
17 . The method of claim 16 , wherein the solvent is comprised of at least 2 solvents, and each solvent has a density of less than 0.9 g/cc.
18 . The method of claim 17 , wherein each of the at least 2 solvents have the density of less than 0.85 g/cc.
19 . The method of claim 16 , wherein an inorganic particulate that is insoluble in the solvent is added to the thermoplastic polymer, prior to or during the dissolving of the thermoplastic polymer.
20 . The method of claim 18 , wherein the density difference is at least 5%.