Compartmentalized chips with similar polymers of different viscosities for improved processability
Compartmentalized chips of at least two chemically similar crystallizable thermoplastic polymers each having a different intrinsic viscosity placed in separate zones are disclosed. These compartmentalized chips exhibit thermal characteristics that are different from the traditional technique of homogeneously combining the two materials into the chip. These compartmentalized chips in their amorphous, crystalline and solid phase polymerized forms exhibit a longer crystallization half time than the homogeneous mixture, thus permitting faster injection cycle times when compared to an equivalent homogenous mixture.
1. A process for manufacturing a pellet with a reduced I.V. gradient comprising the steps of:
(A) manufacturing a compartmentalized chip comprising a first compartment that comprises a first crystallizable thermoplastic polymer and a second compartment that comprises a second thermoplastic crystallizable polymer, wherein the second compartment is located so that at least a portion of the second compartment lies between the centroid of the chip and the first compartment, wherein the intrinsic viscosity of the second crystallizable thermoplastic polymer is greater than the intrinsic viscosity of the first crystallizable thermoplastic polymer;
(B) crystallizing the first crystallizable thermoplastic polymer;
(C) heating the compartmentalized chip in the presence of a driving force to a temperature in the range of 140° C. and the 1° C. below the temperature at which the first crystallizable polymer becomes liquid;
(D) maintaining the chip in the temperature range in the presence of a driving force for sufficient time to increase the intrinsic viscosity of the chip at least 0.05 dl/g.
2. The process of claim 1 wherein at least 85 percent of the repeating polymer units of the second crystallizable thermoplastic polymer have the same chemical structure as at least 85 percent of the repeating units of the first crystallizable thermoplastic polymer.
3. The process of claim 1 , wherein 85 percent of the polymer repeating units of the first crystallizable thermoplastic polymer are ethylene terephthalate.
4. The process of claim 1 , wherein the second crystallizable thermoplastic polymer has been a solid and remelted at least once since its original manufacture.
5. The process of claim 4 wherein at least 85 percent of the repeating polymer units of the second crystallizable thermoplastic polymer have the same chemical structure as at least 85 percent of the repeating units of the first crystallizable thermoplastic polymer.
6. The process of claim 4 , wherein 85 percent of the polymer repeating units of the first crystallizable thermoplastic polymer are ethylene terephthalate.
7. The process of claim 1 , wherein the second crystallizable thermoplastic polymer is selected from the group consisting of industrial waste and postconsumer waste.
8. The process of claim 7 wherein at least 85 percent of the repeating polymer units of the second crystallizable thermoplastic polymer have the same chemical structure as at least 85 percent of the repeating units of the first crystallizable thermoplastic polymer.
9. The process of claim 7 , wherein 85 percent of the polymer repeating units of the first crystallizable thermoplastic polymer are ethylene terephthalate.
10. The process of claim 1 , wherein the second crystallizable thermoplastic polymer is postconsumer polyester.
11. The process of claim 10 wherein at least 85 percent of the repeating polymer units of the second crystallizable thermoplastic polymer have the same chemical structure as at least 85 percent of the repeating units of the first crystallizable thermoplastic polymer.
12. The process of claim 11 , wherein 85 percent of the polymer repeating units of the first crystallizable thermoplastic polymer are ethylene terephthalate.
13. The process of claim 1 , wherein the second crystallizable thermoplastic polymer is FDA regulated postconsumer recycle polyester.
14. The process of claim 13 wherein at least 85 percent of the repeating polymer units of the second crystallizable thermoplastic polymer have the same chemical structure as at least 85 percent of the repeating units of the first crystallizable thermoplastic polymer.
15. The process of claim 13 , wherein 85 percent of the polymer repeating units of the first crystallizable thermoplastic polymer are ethylene terephthalate.