Polymer recyclate processes and products

Abstract

Methods for processing HDPE and/or MDPE recyclates including, but not limited to, polyethylene and polypropylene and compositions therefrom are provided. HDPE and/or MDPE recyclate feedstocks can be visbroken to improve processing characteristics and/or devolatilized to remove waste byproducts to produce processed HDPE recyclate and/or processed MDPE recyclates. Processed HDPE recyclate and/or processed MDPE recyclates are compounded with pre-consumer polyolefins to produce blend compositions having acceptable or even improved processing characteristics. Such pre-consumer polyolefins can also be visbroken to further tailor processing characteristics of such polymer blends. A combination of extruders and/or extruder zones can be used at the same or different locations for visbreaking and/or compounding of both HDPE and/or MDPE recyclate and/or pre-consumer polyolefins.

What is claimed is: 
     
         1 . A method for processing high density polyethylene (HDPE) and/or medium density polyethylene (MDPE) recyclate comprising:
 a. providing a HDPE recyclate feedstock and/or MDPE recyclate feedstock having:
 i) a first density in the range of from 0.925 g/cm 3  to 0.970 g/cm 3 ; 
 ii) a first melt index (I 2 ) in the range of from 0.10 g/10 min. to 1.0 g/10 min.; 
 iii) a first molecular weight distribution (M w /M n ) greater than 6.0; 
 iv) a first weight average molecular weight (“M w1 ”) greater than or equal to 100,000 daltons; and 
 v) a first melt elasticity (“ER”) greater than or equal to 1.0; 
   b. adding the HDPE and/or MDPE recyclate to a first extruder to produce a first HDPE and/or MDPE recyclate melt; and   c. subjecting the first HDPE recyclate melt and/or MDPE recyclate melt to visbreaking conditions to produce a second HDPE recyclate melt and/or MDPE recyclate melt having:
 i) a second density, wherein the ratio of the second density to the first density is greater than or equal to 1.0; 
 ii) a second melt index (I 2 ), wherein the ratio of the second melt index to the first melt index is greater than or equal to 5.0 and/or the second melt index is greater than or equal to 5.0 g/10 min.; 
 iii) a second molecular weight distribution, wherein the ratio of second molecular weight distribution to the first molecular weight distribution is in the range of from 0.25 to 0.60; 
 iv) a second weight average molecular weight (“M w2 ”), wherein M w2 /M w1  is in the range of from 0.10 to 0.70; and 
 v) a second melt elasticity, wherein the ratio of the second melt elasticity to the first melt elasticity is in the range of 0.10 to 0.45, and/or the second melt elasticity is less than or equal to 2.0. 
   
     
     
         2 . The method of  claim 1 , wherein the HDPE recyclate feedstock and/or MDPE recyclate feedstock comprises post-consumer recycled waste, post-industrial recycled waste, or a combination thereof. 
     
     
         3 . The method of  claim 1 , wherein the visbreaking conditions consist of thermal visbreaking. 
     
     
         4 . The method of  claim 3 , wherein thermal visbreaking is performed at a temperature greater than or equal to 300° C. 
     
     
         5 . The method of  claim 1 , further comprise further subjecting the first HDPE recyclate melt and/or MDPE recyclate melt to devolatilization conditions to produce the second HDPE recyclate melt and/or MDPE recyclate melt wherein:
 the HDPE recyclate feedstock and/or MDPE recyclate feedstock has a first volatile organic compound content;   the first HDPE recyclate melt and/or MDPE recyclate melt has a second volatile organic compound content; and   the ratio of the second volatile organic compound content to the first volatile organic compound content is less than or equal to 0.9.   
     
     
         6 . The method of  claim 5 , wherein devolatilization conditions comprise injection and withdrawal of a scavenging gas. 
     
     
         7 . The method of  claim 1 , wherein the method is characterized by one or more of the following:
 i) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first high load melt index (I 21 ), the second HDPE recyclate melt and/or MDPE recyclate melt has a second high load melt index, and the ratio of the second high load melt index to the first high load melt index is greater than or equal to 2.0;   ii) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first melt index ratio (I 21 /I 2 ), the second HDPE recyclate melt and/or MDPE recyclate melt has a second melt index ratio, and the ratio of the second melt index ratio to the first melt index ratio is in the range of 0.30 to 0.60;   iii) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first long chain branching parameter (g′) the second HDPE recyclate melt and/or MDPE recyclate melt has a second g′, and the ratio of the second g′ to the first g′ is less than to 1.0, and/or the first g′ is in the range from 0.70 to 0.99;   iv) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first long chain branching index (“LCBI”) greater than or equal to 0.60, the second HDPE recyclate melt and/or MDPE recyclate melt has a second LCBI, and the ratio of the second LCBI to the first LCBI is less than or equal to 0.40;   v) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first overall polydispersity measure (“PDR”), the second HDPE recyclate melt and/or MDPE recyclate melt has a second PDR, and the ratio of the second PDR to the first PDR is less than or equal to 0.50;   vi) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first complex viscosity ratio, the second HDPE recyclate melt and/or MDPE recyclate melt has a second complex viscosity ratio, and the ratio of the second complex viscosity ratio to the first complex viscosity ratio is less than or equal to 0.50, and/or the second complex viscosity ratio is less than or equal to 10;   vii) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first intrinsic viscosity, the second HDPE recyclate melt and/or MDPE recyclate melt has a second intrinsic viscosity, and the ratio of the second intrinsic viscosity to the first intrinsic viscosity is less than or equal to 0.90; and   viii) the HDPE recyclate feedstock and/or MDPE recyclate feedstock have a first die swell, the second HDPE recyclate melt and/or MDPE recyclate melt has a second die swell, and the ratio of the second die swell to the first die swell is less than or equal to 0.90 and/or the second die swell is less than or equal to 150%.   
     
     
         8 . The method of  claim 1 , wherein a HDPE and/or MDPE recyclate product is formed by withdrawal of the second HDPE recyclate melt and/or MDPE recyclate melt from the first extruder for further processing or pelletizing of the second HDPE and/or MDPE recyclate melt. 
     
     
         9 . The method of  claim 8 , further comprising:
 adding the HDPE and/or MDPE recyclate product and a first polyolefin blend component to a second extruder; and   effecting compounding conditions in the second extruder to form a polyolefin product comprising the melt-blended mixture of the processed HDPE recyclate and/or processed MDPE recyclate product and the first polyolefin blend component.   
     
     
         10 . The method of  claim 9 , wherein the first polyolefin blend component comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof. 
     
     
         11 . The composition of  claim 10 , wherein:
 a. the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof;   b. the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof; and   c. the processed polyolefin recyclate comprises a processed LDPE recyclate, a processed LLDPE recyclate, a second processed HDPE recyclate, a second processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.   
     
     
         12 . The method of  claim 11 , wherein the first polyolefin blend component comprises a virgin HDPE and/or MDPE, a HDPE and/or MDPE recyclate feedstock, a processed HDPE recyclate and/or processed MDPE recyclate, or a combination thereof. 
     
     
         13 . The method of  claim 9 , wherein the HDPE and/or MDPE recyclate product is added in an amount in the range of from 5 wt. % to 90 wt. % based on the combined weight of the HDPE and/or MDPE recyclate product and the first polyolefin blend component. 
     
     
         14 . The method of  claim 9 , wherein the compounding conditions include a temperature less than or equal to 300° C. 
     
     
         15 . The method of  claim 9 , further comprising:
 adding a second polyolefin blend component to a third extruder;   effecting melt conditions in the third extruder to produce a second polyolefin blend component melt; and   withdrawing the second polyolefin blend component melt as the first polyolefin blend component.   
     
     
         16 . The method of  claim 15 , wherein the second blend component comprises a virgin HDPE and/or MDPE, a HDPE and/or MDPE recyclate feedstock, a processed HDPE recyclate and/or processed MDPE recyclate, or a combination thereof. 
     
     
         17 . A composition comprising a polymer blend of:
 a. a first polymer, wherein the first polymer:
 i) is a first processed HDPE recyclate and/or processed MDPE recyclate; and 
 ii) is present in an amount in the range of from 5 wt. % to 90 wt. %; and 
   b. a second polymer, wherein the second polymer:
 i) is a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof; and 
 ii) is present in an amount in the range of from 10 wt. % to 95 wt. %; 
   wherein all weight percentages are based on the combined weight of the first and second polymers.   
     
     
         18 . The composition of  claim 17 , wherein:
 a. the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof;   b. the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof; and   c. the processed polyolefin recyclate comprises a processed LDPE recyclate, a processed LLDPE recyclate, a second processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.   
     
     
         19 . The composition of  claim 17 , wherein processed means subjected to thermal visbreaking and optionally subjected to devolatilization. 
     
     
         20 . A blend comprising:
 a visbroken HDPE and/or MDPE, having a first 12; and   a virgin HDPE and/or MDPE, a HDPE and/or MDPE recyclate feedstock, a processed HDPE recyclate and/or processed MDPE recyclate, or a combination thereof, having a second 12;   wherein:   
       
         
           
             
               
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         i is the i-th component of an n-component blend.