Self-Heating Plastic Can Woos Coffee, Tea, Cocoa Categories
Ontro Inc. (Poway, CA) and Uniloy Milacron (Manchester, MI) have collaborated on the development of a self-heating plastic container for hot beverage and soup applications. Without the help of external heat or power, the package raises beverage temperature to 80°F in about five minutes and maintains the temperature for about 20 minutes.
Pushbutton heat
The internal heat source is activated by pushing a button on the bottom of the container—providing high convenience for travelers, commuters, campers and other on-the-go consumers.
The container features a patented one-piece, two-compartment body molded from one parison on the Uniloy BW 3000DE. Heat is developed inside the container through an exothermic reaction between water and calcium oxide (crushed limestone). When a button, or "puck," installed in the bottom of the container is depressed, the seal separating the two elements breaks allowing them to mix together within the specially designed heating cone. The inner chamber isolates these elements from the container's contents. The heat is transferred through the cone to the beverage, raising temperature 80°F above ambient after five to six minutes.
To activate, the user turns the can upside-down, removes a foil membrane to reveal a "puck" containing the water, and presses a plastic button on the puck which breaks a foil seal separating water and calcium oxide. This allows the water to mix with the calcium oxide in the fluted inner heating cone. After five seconds, the container is turned right-side-up, and the contents are heated. Heat-sensitive inks on the label tell the user when contents are hot.
Original designs called for the two main container components--the heating cone and outer shell--to be produced from two different molds. Uniloy engineers suggested molding the two components from a single parison. The top half of the parison is the outer container shell and the bottom half is the cone. The cone is removed and inserted into the shell, and both welded together. This eliminated handling and storage hassles, and cut the number of mold changes in half.
Six-Layer PP Blow-Molded Structure
Ontro's container is made from six plastic layers. The outside layer is Amoco's new ACCPRO polypropylene (PP), chosen for its ability to resist distortion at high levels of heat without becoming stiff and brittle. The second layer is a regrind mixture of the ground spin domes cut from the cans mixed with a small percentage of virgin PP. A tie layer is next, adhering the regrind layer with an EVOH oxygen barrier. Another tie layer adheres the EVOH with virgin PP on the innermost layer. The tie-in resin is DuPont's Bynel co-extrudable adhesive.
With exception of the metal lid and foil seals, the entire container is recyclable plastic. And even if some of the recyclable containers end up in a landfill, the resultant material from the calcium oxide/water reaction (calcium hydroxide) would assist in breaking down the landfill material.
A leading-edge blow-molding machine produces the new six-layer plastic
self-heating beverage container. The package has won Invention Convention's Invention and New Product Award, has been named a Can of the Year at the Cannex trade exposition and most recently won UCSD CONNECT's Most Innovative New Product of the Year Award.
Precision-Control, Quick-Change Machine
According to Ontro, Uniloy's advanced six-layer BW 3000DE shuttle blow molding machine had the necessary accuracy and repeatability to produce its intricate container, while the machine's shuttle operation allowed quick mold changes for initial testing and short production runs.
Precise control of wall thickness and proper pinch off at the cone tip was critical to the design. Heating cone layer thickness is critical to ensuring maximum heat transfer to the beverage. Outside wall thickness needed to be substantial enough for stacking strength and to ensure insulation of heated beverage from users' hands. Ontro says the BW's parison control reliably holds these critical tolerances, which are quantified by testing samples via microscopy.
In addition to its precise parison control, the BW machine was selected for its quick and easy mold change, needed in Ontro's limited-production and development environment. The company effectively traded the high-output of a wheel machine – with its long changeover times – for the moderate output and mold-change convenience of a shuttle. Insertable molds further minimize changeover time for the company.
The BW 3000DE has easy accessibility for quick changeovers. It can accept molds to 400-mm length, 380-mm width, and provides 100kN of clamping force. The machine is equipped with a W. Müller dual parison six-layer head and Moog TMC control. The closed-loop, user-friendly Moog TMC with proportional control of hydraulics provides excellent repeatability.
The BW 3000DE operates with a take-away system to remove the container/heating cone part from the mold. A down-line trimmer removes top spin dome and separates the two components. Cones are currently inserted into the shell manually, but an automatic system is in the design stages. The components are delivered to a weld station to produce the seamless two-compartment chamber. All downstream equipment is "off-the-shelf," with some components slightly modified. According to Ontro, it didn't want "unicorns," where machine makers would have to reinvent the wheel for each piece.
The current system is geared to produce up to 16 containers per minute, but Ontro's Poway, CA, facility has room for additional blow-molding machines to increase capacity as needed.
In addition to products such as coffee, hot chocolate, tea and low-viscosity soups, the self-heating container could be used for baby formula, which is generally consumed at a lower temperature than coffee. The amount of water and calcium oxide can be adjusted to decrease the overall temperature increase. Ontro is also looking into bottles with threaded or lug cap or a bowl-shaped container with a greater surface area for higher-viscosity products like chunky soups and stews.
For more info: Uniloy Milacron, marketing dept., Tel: 1-800-666-8852 or 734-428-8371; Fax: 734-428-1165; or Danae Marshall Brooker, VP of sales & marketing, Ontro Inc., Tel: 858-486-7200; Fax: 858-486-7204. Websites: www.uniloy.com and www.ontro.com.
Edited by Judy Rice