There are many potential sources of VOC and FOG chemicals in the car's cabin. One way to reduce their presence could be to move to a hybrid mould release system.
Various automotive components, such as steering wheels and seat cushions, are commonly made from moulded polyurethane components. If getting the polyurethane formulation into the mould in the right way is an art form, so is extracting the moulded part. Release agents are often required to assist in this process, and to help ensure that the part has the correct surface finish.
Concentrol has developed a range of hybrid mould release agents that contain 30% solvent. The company said this gives products that maintain efficient mould emptying, and also reduce the amount of VOC in the workplace. This is good for employees on the shop-floor and also the environment, it claimed. They also have lower flammability ratings than solvent-based release agents, making them easier to transport and store.
The products are emulsions that contain water, emulsifying agent, 30% solvent, and 4-8% hydrocarbon waxes, which act as the release agent. The solvent is important, and must have a flash point greater than 62°C. Concentrol said its solvents do not contain benzene, and have levels of aromatic compounds below 20ppm. This means there is almost no odour, and the emulsions have low surface tension and low electrical conductivity.
Companies switching from existing release agents to these hybrid materials need to make minimal changes to the production line, Concentrol claims. Drying times may be longer than conventional release agents, and stainless-steel moulds and pipework are preferred. The release agents should be applied using an aerographic or air-mix nozzle at between 0.3- 0.5 mm diameter and 2-4 bar pressure.
Traditional, solvent-based release agents contain hydrogenated aliphatic hydrocarbons of different distillation ranges. This gives them a range of boiling and flash points. To reduce the difficulty and cost of handling and storing liquids that can be highly flammable liquids, several release agent companies have introduce hybrids that are 50:50 water:solvent mixtures. Concentrol said this is a good intermediate solution for polyurethane manufacturers producing parts like car seats, furniture, soundproofing and steering wheels with a solvent based release agent, and who don’t want to change to a completely water-based system.
‘Moving to a 30% system reduces the cost of the release agent, as there is less solvent in the formulation, and a further 20% reduction in VOC released to the atmosphere [compared to 50:50 systems],’ it said. Finally, because the release agents are much less volatile than solvent-based systems, they are easier to transport and store.
The mixture of solvent and water has advantages over all-water systems. The product freezes at temperatures greater than 0°C, but the solvent protects the emulsion system and at 15°C after having been frozen, the hybrid system has the properties of an unfrozen product, said Concentrol.
The company said that its new Hybrid mould release systems will give parts with the same surface as a standard solvent-based release agent. Using the material also avoids the greasy residue that can be left by water-based systems.