Processes for recycling polystyrene waste

Abstract

There are provided recycled polystyrene polymers having a melt flow index of less than about 25 g/10 min. There are provided processes for recycling polystyrene waste. The processes can comprise dissolving said polystyrene waste in p-cymene under conditions to obtain a polystyrene/p-cymene mixture, adding the polystyrene/p-cymene mixture to a hydrocarbon polystyrene non-solvent under conditions to obtain precipitated polystyrene and washing the precipitated polystyrene with additional portions of hydrocarbon polystyrene non-solvent under conditions to obtain twice-washed polystyrene. The twice-washed polystyrene can optionally be dried and formed into polystyrene pellets. There is also provided recycled polystyrene obtained from such processes for recycling polystyrene waste.

1 . A recycled polystyrene having a melt flow index of less than about 25 g/10 min measured according to ASTM D1238-13 standard and a content of additive(s) of less than about 1 wt %. 
     
     
         2 . The recycled polystyrene of  claim 1 , wherein said recycled polystyrene has a content of additive(s) of less than about 0.5 wt %. 
     
     
         3 - 6 . (canceled) 
     
     
         7 . The recycled polystyrene of  claim 1 , wherein said recycled polystyrene has a melt flow index of from about 1 to about 10 g/10 min. 
     
     
         8 - 18 . (canceled) 
     
     
         19 . The recycled polystyrene of  claim 7 , wherein said recycled polystyrene has an ash content of less than about 1 wt %, measured according to ASTM D5630-13 standard. 
     
     
         20 - 43 . (canceled) 
     
     
         44 . A process for recycling polystyrene waste, comprising:
 dissolving said polystyrene waste in p-cymene under conditions to obtain a polystyrene/p-cymene mixture;   adding said polystyrene/p-cymene mixture to a first portion of hydrocarbon polystyrene non-solvent under conditions to obtain precipitated polystyrene and a first portion of hydrocarbon waste solution;   separating said precipitated polystyrene from said first portion of hydrocarbon waste solution;   optionally repeating said dissolving, adding and separating;   washing said precipitated polystyrene with a second portion of hydrocarbon polystyrene non-solvent under conditions to obtain washed polystyrene and a second portion of hydrocarbon waste solution;   separating said washed polystyrene from said second portion of hydrocarbon waste solution;   washing said washed polystyrene with a third portion of hydrocarbon polystyrene non-solvent under conditions to obtain twice-washed polystyrene and a third portion of hydrocarbon waste solution;   separating said twice-washed polystyrene from said third portion of hydrocarbon waste solution; and   optionally drying said twice-washed polystyrene under conditions to obtain dried polystyrene.   
     
     
         45 . (canceled) 
     
     
         46 . The process of  claim 44 , wherein said polystyrene/p-cymene mixture comprises polystyrene in an amount of from about 10 wt % to about 30 wt %, based on the total weight of said polystyrene/p-cymene mixture. 
     
     
         47 - 56 . (canceled) 
     
     
         57 . The process of  claim 44 , wherein said polystyrene/p-cymene mixture comprises insoluble material and said process further comprises filtering said polystyrene/p-cymene mixture under conditions to remove said insoluble material prior to adding said polystyrene/p-cymene mixture to said first portion of hydrocarbon polystyrene non-solvent. 
     
     
         58 - 59 . (canceled) 
     
     
         60 . The process of  claim 44 , wherein said conditions to obtain said precipitated polystyrene and said first portion of hydrocarbon waste solution comprise adding said polystyrene/p-cymene mixture to said first portion of hydrocarbon polystyrene non-solvent at the boiling point of said hydrocarbon polystyrene non-solvent and agitating for a time for diffusion of said p-cymene from said polystyrene/p-cymene mixture into said hydrocarbon polystyrene non-solvent to proceed to a sufficient extent. 
     
     
         61 - 62 . (canceled) 
     
     
         63 . The process of  claim 60 , wherein greater than about 90 wt % of said p-cymene in said polystyrene/p-cymene mixture diffuses into said hydrocarbon polystyrene non-solvent, based on the total weight of said polystyrene/p-cymene mixture. 
     
     
         64 . The process of  claim 44 , wherein the ratio by volume of said first portion of hydrocarbon polystyrene non-solvent to said polystyrene/p-cymene mixture is from about 2:1 to about 4:1. 
     
     
         65 - 66 . (canceled) 
     
     
         67 . The process of  claim 44 , wherein said conditions to obtain said washed polystyrene and said second portion of hydrocarbon waste solution comprise adding said second portion of hydrocarbon polystyrene non-solvent to said precipitated polystyrene at the boiling point of said hydrocarbon polystyrene non-solvent and agitating for a time for diffusion of said p-cymene from said precipitated polystyrene into said hydrocarbon polystyrene non-solvent to proceed to a sufficient extent. 
     
     
         68 - 71 . (canceled) 
     
     
         72 . The process of  claim 67 , wherein said washed polystyrene comprises less than about 0.3 wt % p-cymene. 
     
     
         73 - 76 . (canceled) 
     
     
         77 . The process of  claim 72 , wherein said conditions to obtain said twice-washed polystyrene and said third portion of hydrocarbon waste solution comprise adding said third portion of hydrocarbon polystyrene non-solvent to said washed polystyrene at the boiling point of said hydrocarbon polystyrene non-solvent and agitating for a time for diffusion of said p-cymene from said washed polystyrene into said hydrocarbon polystyrene non-solvent to proceed to a sufficient extent. 
     
     
         78 - 80 . (canceled) 
     
     
         81 . The process of  claim 77 , wherein said twice-washed polystyrene comprises less than about 0.1 wt % p-cymene. 
     
     
         82 - 86  (canceled) 
     
     
         87 . The process of  claim 44 , wherein at least one of said first portion of hydrocarbon polystyrene non-solvent, said second portion of hydrocarbon polystyrene non-solvent and said third portion of hydrocarbon polystyrene non-solvent comprises a hydrocarbon polystyrene non-solvent having a boiling point at 1 atm of pressure of from about 98° C. to about 110° C. or about 105° C. to about 110° C. 
     
     
         88 - 89 . (canceled) 
     
     
         90 . The process of  claim 44 , wherein said first portion of hydrocarbon polystyrene non-solvent, said second portion of hydrocarbon polystyrene non-solvent and said third portion of hydrocarbon polystyrene non-solvent comprise a C 6 -C 8  alkane or a petroleum distillate. 
     
     
         91 - 98 . (canceled) 
     
     
         99 . The process of  claim 44 , wherein said first portion of hydrocarbon polystyrene non-solvent, said second portion of hydrocarbon polystyrene non-solvent and said third portion of hydrocarbon polystyrene non-solvent comprise n-heptane. 
     
     
         100 - 113 . (canceled) 
     
     
         114 . The process of  claim 44 , wherein said conditions to obtain said dried polystyrene comprise drying said twice-washed polystyrene for a temperature and time for removal of remaining hydrocarbon polystyrene non-solvent to proceed to a sufficient extent. 
     
     
         115 . The process of  claim 114 , wherein said twice-washed polystyrene is dried at a temperature of from about 115° C. to about 125° C. 
     
     
         116 - 117 . (canceled) 
     
     
         118 . The process of  claim 44 , wherein said polystyrene waste comprises polar impurities and said process further comprises washing said polystyrene waste with a polar organic solvent under conditions to remove said polar impurities. 
     
     
         119 . The process of  claim 118 , wherein said polar organic solvent comprises methanol or ethanol. 
     
     
         120 - 153 . (canceled) 
     
     
         154 . The process of  claim 44 , wherein said polystyrene waste is post-industrial waste, post-consumer waste or a combination thereof. 
     
     
         155 - 174 . (canceled) 
     
     
         175 . A method for managing recycling of polystyrene comprising:
 providing a customer with at least one container for storing polystyrene waste;   providing said customer with instructions on dissolving said polystyrene waste into said at least one container by using at least one solvent;   optionally monitoring concentration of said polystyrene waste into said at least one solvent and/or a volume of liquid and/or solid contained in said at least one container;   removing at least a portion of a liquid content contained in said at least one container and that comprises said polystyrene waste dissolved into said at least one solvent;   optionally adding a quantity of said at least one solvent into said at least one container; and   transporting said at least a portion of said liquid content contained in said at least one container into a facility whereat said polystyrene waste is recycled or treated for converting said polystyrene waste into recycled polystyrene,   wherein recycling of said polystyrene or converting of said polystyrene waste into recycled polystyrene is carried out by a method as defined in  claim 44 .   
     
     
         176 - 179 . (canceled)