APPARATUS AND METHODS FOR MANUFACTURING BIODEGRADABLE, COMPOSTABLE, DRINK STRAWS FROM POLYHYDROXYALKANOATE MATERIAL
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.
1 . A drink straw, comprising:
a tubular body, wherein the tubular body is made of a material comprising at least 50% polyhydroxyalkanoate (PHA).
2 . The drink straw of claim 1 , wherein the tubular body has a length, and wherein the length of the tubular body is in a range of about five inches to about 10.25 inches.
3 . The drink straw of claim 2 , wherein the length of the tubular body is in a range of about 7.75 inches to about 10.25 inches.
4 . The drink straw of claim 1 , wherein the tubular body has an outer cross-sectional diameter, an inner cross-sectional diameter, and a material thickness defined by the outer cross-sectional diameter and the inner cross-sectional diameter, and
wherein the material thickness is in a range of about five mils to about ten mils.
5 . The drink straw of claim 4 , wherein the material thickness of the tubular body is in a range of about six mils to about seven mils.
6 . The drink straw of claim 5 , wherein the tubular body has a length, wherein the length of the tubular body is in a range of about five inches to about 10.25 inches.
7 . The drink straw of claim 1 , wherein the drink straw is marine-biodegradable, soil-biodegradable, and compostable.
8 . The drink straw of claim 7 , wherein the drink straw degrades by about 80% in a marine environment in less than two years.
9 . The drink straw of claim 7 , wherein the drink straw degrades by about 88% in a marine environment within about 97 days.
10 . The drink straw of claim 1 , wherein the drink straw defines a shovel-shaped end portion thereof.
11 . An extruder for use in apparatus for manufacturing a drink straw, the extruder comprising:
a cylindrical barrel; and
an extruder screw that extends through the barrel,
wherein the extruder screw is configured to draw a raw material comprising at least 50% polyhydroxyalkanoate (PHA) from a hopper into a first end of the extruder barrel and to push molten PHA material out of a second end of the extruder barrel toward a die; and
wherein the extruder is configured to melt the raw PHA material to form the molten PHA material, and wherein the extruder to have a temperature profile such that the first end of the extruder barrel is at a first temperature and the second end of the extruder barrel is at a second temperature that is greater than the first temperature.
12 . The extruder of claim 11 , wherein the extruder is configured such that temperature within the extruder increases from the first end of the extruder barrel to the second end of the extruder barrel.
13 . The extruder of claim 11 , wherein the first temperature is in a range from about 290° F. to about 340° F., and the second temperature is in a range from about 340° F. to about 390° F.
14 . The extruder of claim 13 , wherein the first temperature is about 300° F., and the second temperature is about 350° F.
15 . The extruder of claim 11 , wherein the extruder screw is a low-shear, low-volume, non-mixing screw that is configured to meter the molten PHA material toward the die.
16 . 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 lower than the first temperature and is configured to receive first cooled PHA material from the first chamber and to produce second cooled PHA material.
17 . The two-stage water bath of claim 16 , wherein the water contained by the first chamber has a temperature of between about 125° F. and 175° F., and wherein the water contained by the second chamber has a temperature of between about 70° F. and 90° F.
18 . The two-stage water bath of claim 17 , 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.
19 . The two-stage water bath of claim 18 , 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.
20 . The two-stage water bath of claim 16 , 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 period of time ranging from 1.5-2.0 seconds 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 period of time ranging from 1.5-2.0 seconds to produce the second cooled PHA material.