Cannon Viking, a company of the Cannon Group, is set to celebrate three decades of the CarDio system – a patented eco-friendly process using liquid carbon dioxide (CO2) to manufacture today both low- and high-density polyurethane foams. Prior to joining the Cannon Group in 1989, Viking Engineering was already a leading and well-established OEM designing and producing metering and mixing equipment for flexible and rigid polyurethane foams.
“There was a persuasive, and growing need at the time to ban halogenated blowing agents and other volatile organic compounds from the production of expanded PU foams. Numerous advantages characterized carbon dioxide which has zero ozone depletion potential and an extremely low global warming potential, is inexpensive, non-toxic and does not consume isocyanates when reacting, contrary to water, offering significant cost savings, but it was very difficult to control in a formulation at room temperature as it expands three times more than existing blowing agents,” said Jonathan Rayner, Sales Director at Cannon Viking.
Combining mechanical engineering and chemical formulation expertise, the late, and highly respected Carlo Fiorentini together with a well-known foam technologist, Tony Griffiths, developed the first commercial process to add and successfully use natural liquid carbon dioxide as a physical blowing agent in PU foam production on a continuous basis. Cannon set up a pilot plant and quickly defined a reaction process to tame the turbulent expansion of the foam generated by CO2 that stays liquid only above 5.2 Bar (754 psi). Novel equipment to overcome and control pressure, difficult mixing behavior and distribution was designed and following successful trials the innovative CarDio system was patented and launched in 1993.
Core to the patented CarDio system is a proprietary steel gatebar that works as a pressure reducing and blend distribution device. Applying Cannon’s expertise in precision machining with tolerances measured in microns, an airless gatebar which provides a lower exit velocity of the reacting blend was developed and introduced in 2002.
This significant improvement offered further unique features and benefits to the CarDio system by practically eliminating remaining miniscule voids that could appear in foams manufactured with certain chemicals. It also allowed customers to process the maximum level of liquid CO2 in their foams as well as the widest range of chemicals including high viscosity polyols and graft polyols, as well as a wide variety of powders and fillers such as calcium carbonate (CaCO3) and barium sulphate BaSO4 – for increased foam density and soundproofing, respectively – and melamine – for fire retardancy.
Forced by a high-pressure mixing head through a square expansion chamber that leads to a thin, progressively wider gap, the blend gradually loses pressure allowing the liquid CO2 to convert to its gaseous state. The geometry of the airless gatebar provides a highly homogenous froth of foam evenly laid across the entire width of the conveyor, characterized by a very uniform structure.
Further benefits include the use of filler particles, such as powders and flakes, of up to 400 microns. Generous slots, double the diameter of particles, avoids build-up and blockage. Another advantage is switching color and grades within a very short transition span of only 25 cm, drastically reducing waste.
The CarDio system also allows for exceptionally long production runs of up to 5 hours for most used grades, with or without fillers and can be supplied as an integral part of a new custom-built Cannon Viking Maxfoam or Maxfoam Elite continuous slabstock facility or installed as a retro-fit in an existing foaming plant – irrespective of the machine manufacturer.
Cannon Viking has developed a gatebar (patent-pending) for non-CO2 liquid laydown techniques which offers all the advantages of the CarDio system and installed as a retrofit for manufacturers who continue to use traditional foaming methods.