Injection Molded Foam
Indention Load Deflection (ILD)
The ILD rating tells if the material is soft or hard. The higher the ILD rating, the firmer the foam will be.
Density is another factor in determining how well a memory foam bed will perform. The density is mostly the density of the cells within a block of foam. The more cells you have, the denser the foam, and therefore more little cells to work for you. But also, the higher the density, the more material weight that has to be used, and therefore the higher the material cost of production. There are foam systems (the chemicals that are used to make the foam) that can achieve higher densities, and there are foam systems that can achieve lower densities.
MDI vs TDI
There are 2 different types of “FOAM SYSTEMS” (chemicals) that are used to make foam:
TDI System (toluene di-isocyanate)
MDI System (methylene di-phenyl di-isocyanate)
TDI Systems are primarily used to make CUT FOAM. It is poured onto very wide and large moving conveyors, allowing a very large BUN (sometimes the size of a room) to be made, which is later cut to smaller sizes and fabricated into the shape that is needed. TDI can be made at very low densities, and therefore offer a cheap way of making foam. It is also a TOXIC system, creating very serious environmental issues. In China, the molded foam that almost all factories make are made with TDI systems. Although the shape of the molded foam is achieved, there is no density to the foam and therefore very little RESILIENCE. Because of this lack of resilience, theTDI based foams will collapse and become FLAT after a period of use.
MDI Systems are primarily used in MOLDED FOAM applications. They are NON-TOXIC, and CANNOT be made at low densities. Therefore, an MDI based foam will start at densities that are much higher than any TDI based system, and then can go to much higher density levels.
At 9to5 Seating we wanted to use a foam system that was based on MDI rather than TDI. This decision was based on the world’s increasing concern regarding both the short and long term health hazards of isocyanates in general and TDI in particular.
MDI is by far the least hazardous of the commonly available isocyanates, since its vapor pressure is some 2500 times less than TDI at ambient temperatures. This fact makes handling, storage and utilization of the chemical much safer, while TDI is now classified as toxic and considered carcinogenic in many areas. By using MDI, we are confident that we are much less likely to cause health problems either to ourselves or to people in the immediate neighborhood. The main disadvantage of MDI is that it is considerably more expensive than TDI adding 50% to our raw material costs. This we feel is a small price to pay for a clear conscience. We hope that our customers will feel the same.
The equipment used plays an extremely important part in the quality of foam made. This is mainly due to the level of control of certain properties during the mixing of Isocyanate and Polyol. Precise control of Pressure, Temperature, Metering, and Ratio of each component during the mixing process determines the quality of foam made.
The 2 most commonly used types of equipment are Low Pressure Mixing Machines and High Pressure Mixing Machines.
Low Pressure Machines
Low pressure machines are programmed to measure the quantity of Iso or Polyol on a volumetric theoretical value. This is not an accurate means of measurement used in each cycle; and therefore the eventual Ratio of the mix in each cycle will be different than what is required.
The mixing of the 2 chemicals together in the Mixing Head is done by means of a revolving screw (as in a meat grinder), and the resulting mix is not homogeneously mixed, causing “dead foam” spots in areas of the foam made.
High Presuure Machines (9 to 5 Seating uses this method)
The tanks containing Iso and Polyol in a High Pressure System, as well as the entire Metering, Mixing, and Pouring mechanisms are constantly maintained under extremely high Hydraulic Pressure. Consequently, the volume of material passing through a metering device per mili second can be precisely measured, and programmed.
The Mixing Head of a High Pressure Machine is a sophisticated piece of precisely engineered component that allows for the entrance of each chemical into a mixing chamber under extremely high pressure, resulting in an absolutely homogeneously mix. Furthermore, the mixing chamber of a High Pressure machine is automatically cleaned of any residue after completion of every pour-cycle, therefore eliminating any possibility of contamination from one pour to the next.
9 to 5 Seating owns and operates 2 state of the art, computer controlled production lines of High Pressure Equipment. They control very precisely the Temperature, Pressure, and the homogeneous mixing of the 2 chemicals that make the foam.
Most molded foam manufacturers in China have been using a TDI system of chemicals to save cost. The apparent visual result looks very much similar to a well made MDI molded foam made. However, other than the toxic properties of the TDI chemical system used by such manufacturers, the molded foam made in this way has much lower density than one made with MDI, and also the diminished resilience of the TDI Molded Foam will, over a short period of time, cause the foam to collapse and lose its characteristics.
9 to 5 Seating has been exclusively purchasing the MDI chemical system it uses from the best and the most reputable supplier of MDI chemical system in the world, namely BASF. The much higher price paid for this high quality product is compensated by the life lasting quality of molded foam manufactured by 9 to 5 Seating at its plant.