Polymer coated paperboard container and method
A method of forming a coating on a cylindrical paperboard container having a closed end. The method includes the steps of heating a gas from a first temperature to a second temperature; providing the gas to a first inlet of a nozzle; providing a polymer in a liquid state at a third temperature; providing the polymer to a second inlet of the nozzle; and spraying the polymer onto the cylindrical paperboard container using the nozzle; wherein the second temperature is greater than the third temperature; and the second temperature and third temperature are such that the gas maintains the polymer in the liquid state at least until the polymer comes into contact with the cylindrical paperboard container. A system for applying a coating to a plurality of cylindrical paperboard containers and a container for a consumer product are also provided.
1. A system for applying a coating to a plurality of cylindrical paperboard containers, comprising:
a nozzle having a spray zone;
a gas source that provides heated compressed air to a first inlet of the nozzle;
a polymer source that provides amorphous polypropylene in a liquid state to a second inlet of the nozzle;
a first valve within the nozzle, the first valve configured to move between a first open position and a first closed position so as to permit or prevent flow of the heated compressed air and the amorphous polypropylene through an outlet of the nozzle;
a second valve within the nozzle proximate the second inlet, the second valve configured to move between a second open position and a second closed position so as to permit or prevent flow of the amorphous polypropylene to the first valve;
a conveying system structured and arranged to sequentially convey the plurality of cylindrical paperboard containers through the spray zone; and
an electronic controller configured to selectively control the first valve by moving the first valve between the first open position and the first closed position, the electronic controller configured to selectively control the first valve with an actuator to permit flow through the nozzle to spray the heated compressed air and the amorphous polypropylene onto one of the plurality of cylindrical paperboard containers when the conveying system positions the one of the plurality of cylindrical paperboard containers in the spray zone and to prevent flow through the nozzle when a gap between adjacent ones of the plurality of cylindrical paperboard containers is in the spray zone.
2. The system of claim 1 , wherein the nozzle includes an air atomization, external mixing nozzle.
3. The system of claim 1 , wherein the amorphous polypropylene has a molecular weight and surface tension such that the heated compressed air shears the amorphous polypropylene into droplets at a location external of the nozzle.
4. The system of claim 1 , further comprising:
an extruder configured to heat and liquefy the amorphous polypropylene, wherein the amorphous polypropylene is initially in a form of solid beads.
5. The system of claim 4 , wherein each of the solid beads has an average diameter within the range of 1 mm to 3 mm.
6. The system of claim 1 , wherein the electronic controller is configured to move the first valve to the first open position and the second valve to the second closed position to purge the nozzle.
7. The system of claim 1 , wherein the amorphous polypropylene has an average molecular weight (Mw) of about 14,000.