Apparatus and methods for manufacturing biodegradable, compostable, drink straws from polyhydroxyalkanoate material

Abstract

Apparatus and methods for manufacturing compostable, biodegradable drink straws from polyhydroxyalkanoate (PHA) material are disclosed herein. Such apparatus may include a hopper that contains raw PHA material, an extruder that receives the raw PHA material from the hopper and produces extruded PHA material, one or more waters baths that cool the extruded PHA material, a puller that pulls a tubular stream of PHA material through the system, and a cutter that is configured to cut the stream of PHA material into finished straws. The finished straws may be soil- and marine-biodegradable, as well as home- and industrial-compostable.

What is claimed is: 
     
         1 . A two-stage water bath for use in apparatus for manufacturing a drink straw, the water bath comprising:
 a housing;   a wall disposed within the housing, wherein the wall and the housing cooperate to define a first chamber within the housing and a second chamber within the housing, wherein the wall is disposed between the first chamber and the second chamber, wherein the wall separates the first chamber and the second chamber;   wherein the first chamber contains water having a first temperature and is configured to receive extruded PHA material from an extruder, and   wherein the second chamber contains water having a second temperature that is different from the first temperature and wherein the second chamber is configured to receive first cooled PHA material from the first chamber and to produce second cooled PHA material.   
     
     
         2 . The two-stage water bath of  claim 1 , further comprising:
 a sizing tube that controls an inner diameter and wall thickness of the straw,   wherein the sizing tube has an outer diameter that corresponds to the inner diameter of the straw, and a plurality of holes through which the extruded PHA material is pulled to an outer surface of the sizing tube.   
     
     
         3 . The two-stage water bath of  claim 1 , further comprising a gasket in the wall that separates the first chamber from the second chamber, wherein the first cooled PHA material is pulled through the gasket into the second chamber. 
     
     
         4 . The two-stage water bath of  claim 1 , wherein the second temperature is less than the first temperature. 
     
     
         5 . The two-stage water bath of  claim 4 , wherein the first temperature is between about 125° F. and 175° F., and wherein the second temperature is between about 70° F. and 90° F. 
     
     
         6 . The two-stage water bath of  claim 1 , wherein the second temperature is greater than the first temperature. 
     
     
         7 . The two-stage water bath of  claim 6 , wherein the first temperature is between about 70° F. and 90° F., and wherein the second temperature is between about 125° F. and 175° F. 
     
     
         8 . The two-stage water bath of  claim 1 , wherein the extruded PHA material is pulled through the first chamber at a rate that allows for the extruded PHA material to remain in the first chamber for a first predefined period of time to produce the first cooled PHA material, and wherein the first cooled PHA material is pulled through the second chamber at a rate that allows for the first cooled PHA material to remain in the second chamber for a second predefined period of time to produce the second cooled PHA material. 
     
     
         9 . The two-stage water bath of  claim 8 , wherein the first predefined period of time is in a range of 1.0 seconds to 2.0 seconds, and the second predefined period of time is in a range of 1.0 seconds to 2.0 seconds.