A Brief Talk on Polyurethane Soft Foam Flame Retardant Sponge

A Brief Talk on Polyurethane Soft Foam Flame Retardant Sponge

Flame retardant soft foam (flame retardant sponge) is often used on export cotton and high-end furniture cotton. In the past 14 years, the physical properties of flame-retardant sponges have gradually shifted from focusing on the burning time and speed of flame-retardant sponges to focusing on the smoke density, thermal weight loss and oxygen index of flame-retardant sponges. The so-called oxygen index is the value of how much oxygen makes the flame-retardant sponge burn, that is, the relationship between the oxygen content and the starting combustion environment of the sponge. The unit is%. Generally speaking, it is difficult for the polyurethane polyether soft foam to reach the oxygen index of 30%. In recent years, flame-retardant sponges have been added with environmental protection standards. The flame retardants used in flame-retardant sponges have also changed from halogen flame retardants to environment-friendly flame retardants, and there is a tendency to rely more on melamine (some flame-retardant sponges only add melamine).
No matter what flame retardant is used, the physical properties of the sponge will change greatly. For example, the sponge is easy to burn the core (the result of the reaction of water and isocyanate promoted by the flame retardant). For example, the tensile strength of the flame retardant sponge will become much worse (the result of the inhibition of isocyanate cross-linking reaction by the flame retardant raw material). For example, the hardness of the flame retardant sponge will decrease (the result of the inhibition of isocyanate cross-linking reaction by the flame retardant raw material). In actual foaming, the flame-retardant sponge seems to be more delicate than the non-flame-retardant sponge: it is easy to break the foam or crack inside (the result of the inhibition of isocyanate cross-linking reaction by the flame-retardant raw material), and the addition of some flame retardants makes the sponge easy to burn the core and slow to ripen (the result of the inhibition of isocyanate cross-linking by the flame retardants, which is a contradiction and not good balance).

From the situation mentioned above, the flame retardant sponge is more fragile than the non-flame retardant sponge, both in the starting process and after forming, so it is necessary to be gentle when producing the flame retardant sponge. The dosage of flame retardant is related to the density of sponge, the concentration of flame retardant, the dosage of isocyanate and water. In actual combat, it was found that the softer the foam, the better the fire retarding effect of the foam with the same density and the same fraction of flame retardant. Under no special circumstances, flame-retardant silicone oil is used to produce flame-retardant sponges. Although flame-retardant silicone oil can also produce flame-retardant sponges, flame-retardant silicone oil is more conducive to the dispersion of flame retardants, improving the flame-retardant effect by 10% to 30%.
For the indicator of thermal weight loss of soft foam flame retardant test, the following measures are conducive to reducing the thermal weight loss and reaching the test standard: adding inorganic stone powder (the most stable stone), increasing the use of isocyanate (the stability of the benzene ring), using low molecular weight polyether (the sponge produced by polyether with high molecular weight is poor in thermal stability), using MDI or PAPI (polyphenyl ring), and the proportion of water and isocyanate in polyether should not be too small (the hard segment of the sponge should not be too small), etc. It can be seen from the above that the sponge with too high density is not easy to overheat the weight loss detection standard. The thermal weight loss detection of the high resilience flame-retardant sponge is more difficult than that of the ordinary foam flame-retardant sponge. The sponge with a density of 20~30 is relatively balanced in all aspects of the flame-retardant test, which may be the reason why the density of most flame-retardant soft foam is in this range.

Sponge production technology has its particularity. It is one thing to know how to do it, and another to do it well. The multidirectional nature of the sponge response makes the people who can do it at will, and makes the unfamiliar people nervous. Our life is also a multi-directional choice and change.