Polyurethane (short name: PUR or PU) is a synthetic material that is produced by the reaction of the liquid isocyanates with polyols. Both chemicals must be mixed with each other to become a polyurethane. Important requirements are the correct mixing ratio and the consistent mixing of both components. In addition to polyol and isocyanate, several additives are added in order to get modified properties. These additives are catalysts, blowing agents, paint and other fillers such as glass fibers or chalk.
The two liquid base materials are difficult to mix, so mixing is of great importance. If the components are not sufficiently well mixed, no complete reaction is possible.
High and low pressure casting processes
secutex produces polyurethane on both high-pressure and low-pressure casting machines. The high-pressure systems are mostly used for foams or spray systems, the low-pressure casting systems have a better mixing and are used for high-quality, compact casting systems.
1. High pressure casting process
The two components isocyanate and polyol are mixed under high pressures (100 to 200 bar) in the mixing chamber of the PU mixing head. The high pressure in the mixing head is achieved by combining a high-pressure pump and a nozzle. The nozzle is located directly in the mixing head in front of the mixing chamber. The high pressure mixing head does not require a driven mixer, the mixing is done by the kinetic energy of the material.
A special form are the spraying machines. Here the highly reactive polyurea systems are being processed under high pressure.
secutex has two powerful high-pressure casting machines and a total of four spraying systems.
2. Low pressure casting process
When producing PU in a low-pressure process, the two components isocyanate and polyol are mixed at low pressure in a low-pressure mixing head. The homogeneous mixing is achieved by using a driven mixer which is located in the mixing head. In contrast to the high-pressure process, the pump pressure in the low-pressure process is primarily used to transport the material.
secutex has two high-performance 4K low-pressure casting machines and
five standard 2K casting machines. One casting machine has a very low volume and is suitable for the production of small parts. Another machine has a capacity of up to 30l per minute, so that large parts can be produced reliably and efficiently.
3. Other plant technology
The casting machines are integrated into a total of three casting lines, the sometimes required mould temperatures are achieved by heating tables and/or large continuous ovens.