Q&A Frequently Asked Questions

If soft urethane foam discolors due to sunlight, will its performance remain unchanged?

The time it takes to determine that the surface of flexible urethane foam has discolored varies significantly depending on the influence of sunlight: from a few hours in direct summer sunlight to several weeks to several months in a warehouse that does not receive direct sunlight, and even over a year if packed in a dark place. Fluorescent lighting can also cause discoloration.
This discoloration caused by sunlight is thought to occur because some of the polymer chains in the urethane foam change to polymer chains that are more likely to develop color. Therefore, since this is different from the severing of polymer chains, it is thought that discoloration does not immediately lead to a deterioration in physical properties.

What common household chemicals will attack flexible urethane foam?

The chemical resistance of flexible urethane foam is as follows:

Benzine, gasoline, kerosene	It will swell a little when applied, but will return to its original state once it dries. When swollen, the mechanical strength decreases, so please avoid using it in that state.
Soapy water and detergent	There is no problem with normal use, but soaking for a long period of time will cause gradual deterioration. Some toilet and tile cleaners in particular are highly acidic or alkaline, so be sure to rinse thoroughly with water after use (especially avoid using chlorine bleach).

What is the heat and cold resistance of soft urethane foam?

Soft urethane foam has excellent heat and cold resistance and can be used in temperatures ranging from -20°C to 80°C.
However, although this varies depending on the type of urethane foam, it generally takes about 500 to 700 days for its strength to be halved when used continuously at 80°C.
Therefore, there are no problems with heat resistance or cold resistance during normal use. "Polyester foam" has excellent oil resistance, abrasion resistance, and mechanical strength, and the diameter of the air bubbles can be easily changed, so it is used for special purposes such as foam materials and filter materials.

Will soft urethane foam become worn out after long-term use?

The phenomenon in which the thickness of soft urethane foam decreases when a load is applied is called "sag," and the extent of this is generally measured using the test methods called compression residual strain and repeated compression residual strain in JIS K 6400-4.
Less sagging means less "compressive residual strain" and easier recovery.
Compared to fiber cotton and metal springs, urethane foam is characterized by its low density (lightweight) and low sagging. However, actual usage conditions vary greatly, so it is difficult to say "how many percent of thickness loss will occur over how many years of use." However, generally, the heavier the load over a long period of time and the lower the foam density relative to the load, the greater the sagging. If a large compressive load will be applied over a long period of time, purchase a high-quality soft urethane foam with appropriate low sagging properties from a member company of the Urethane Foam Industry Association with strict quality control. Furthermore, the revised JIS K 6401 now allows for classification of sagging resistance into classes (X, V, S, A, L).
Please make use of this classification as it serves as a measure to distinguish the tendency of soft urethane foam to sag.