Mechanical Cooling and Rapid Curing Equipment

Mechanical cooling and rapid curing are foam block curing processes developed for the production of low-density polyurethane foam using a full-water foam formula instead of auxiliary foaming agents like chlorofluorocarbons, for environmental protection of the ozone layer. It is referred to as "enviro" internationally. When producing low-density foam blocks with a high water-content formula, the foam block's core temperature can rise sharply due to the efficient thermal effect of the foaming reaction, and without the evaporative heat absorption from auxiliary foaming agents, the temperature may reach or even exceed the self-ignition danger limit. Enviro was developed specifically to address this situation and is a process for curing foam blocks.

In essence, the mechanical cooling and curing process involves using forced air cooling within an enclosed space to rapidly lower the temperature of the foam block, preventing foam oxidation and self-ignition, thereby ensuring production safety.

Figure 1 shows a schematic diagram of the mechanical cooling and rapid curing device. As shown in the figure, the curing device is a sealed enclosure, and foam blocks are transported into the cooling and curing device by a conveyor belt. Before entering the device, both sides of the foam block are sealed with polyethylene film. The conveyor belt is a perforated circular rubber belt, placed beneath a perforated plate surface with an exhaust pipe. Air is drawn through the holes to firmly adhere the film to the foam block’s sides. Ambient air enters from the top of the block, passes through the foam, and flows into the exhaust channel. The foam is cooled, and the released steam is removed. In the second and third stages, low-temperature heat exchangers are used to cool circulating air, further cooling the foam and removing remaining steam and heat.

Figure 1: Schematic of Mechanical Cooling and Rapid Curing

• The main advantages of the mechanical cooling and rapid curing process are as follows:
• It allows for the production of low-density foam without the use of auxiliary foaming agents.
• The process gases are easy to capture and treat, which is beneficial for environmental protection.
• It shortens the curing cycle, reducing foam block storage time.
• It improves product performance consistency, particularly uniformity in hardness distribution.
• The physical properties of the foam are not affected by changes in atmospheric conditions.