Foam is made-up from many tiny little cells that make tiny little cell-walls, all connected together, to make the MASS structure of foam. Imagine the cross-section of a bread bun.

When weight is placed on a piece of foam, the foam structure’s cell-walls would collapse, but in doing so the cell-walls also provide a COUNTER-RESISTANCE to the weight, thus creating the RESILIENCE (imagine the structure of the Golden Gate Bridge, and how relatively thin pieces of steel and wire can hold-up so much weight).

Without resilience, the collapsed walls can take the shape of the weight (as in memory foam – not offering any support to the weight), or eventually flatten-out completely and therefore eliminate the functionality that is expected from foam. The space between all these tiny little cell-walls is filled with AIR, and as the foam is compressed (causing the cell-walls to collapse) the air that was occupying the space in between the cell-walls flows out of the foam-mass. This can easily be noticed when you sit in a chair (with poor ventilation) and you hear the noise of the air trying to escape from the seat-foam.

If the cells are closed cells, the foam structure would be made-up of many tiny little bubbles with no air (or very little air) in between the bubbles; thus creating something comparable to a BALLOON (or a mass made from many little balls connected together with no air in between them). If you go to the Gym, you will see large plastic balls that you can sit on and do sit-ups. Or a better comparison would be the different experience of laying down on an AIR MATTRESS and then a FOAM MATTRESS. The air mattress more like keeps you up in the air, contouring to the shape of your body, but creating like a container for your body; whereas the foam mattress will also conform to the shape of your body – but at the same time creating a counter weight (depending on the weight of different parts of your body).

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.

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, the TDI 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

The tanks containing Iso and Polyol in a High Pressure Sustem, 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.

*Click here to watch video of Injection Molded Foam