Blowing agents of the tetrazoles and their derivatives

In a process for the production of cellular products which comprises incorporating a blowing agent into rubber or a synthetic polymer and then heating to activate the blowing agent, the improvement which comprises using as the blowing agent tetrazole compounds represented by the formulae (II), (III) and (V):

• ##STR5## wherein R.sub.2 is selected from the group consisting of H, --OH, --COOH, --SO.sub.3 H, --NO.sub.2, halogen and --NH.sub.4 R.sub.5 wherein R.sub.4 and R.sub.5 each are H or C.sub.1 to C.sub.4 alkyl, C.sub.1 to C.sub.6 alkyl, C.sub.3 to C.sub.6 cycloalkyl or C.sub.2 to C.sub.6 alkenyl, optionally substituted by C.sub.1 to C.sub.6 alkyl, --OH, --COOH, --SO.sub.3 H, --NO.sub.2, halogen, --NR.sub.4 R.sub.5 wherein R.sub.4 and R.sub.5 are as defined above or, R.sub.2 can be phenyl, benzyl or phenethyl radicals optionally substituted by 1 to 3 halogen, --OH, NO.sub.2, --NR.sub.4 R.sub.5, wherein R.sub.4 and R.sub.5 are as described above, C.sub.1 to C.sub.4 alkyl and esters or amides of lower carboxylic acids;
• R.sub.3 is selected from the group consisting of C.sub.5 to C.sub.6 alkylene, cycloalkylene or alkenylene, unsubstituted or substituted by C.sub.1 to C.sub.6 alkyl, --OH, --COOH, SO.sub.3 H, --NO.sub.2, halogen, NR.sub.4 R.sub.5 wherein R.sub.4 and R.sub.5 are as defined above, --O--, --S--, --SO.sub.2, --CO--, --phenylene or bisphenylene, said phenylene or bisphenylene being unsubstituted or substituted by 1 to 8 halogens, --OH, --NO.sub.2, esters or amides of lower carboxylic acids, NR.sub.4 R.sub.5, wherein NR.sub.4 and R.sub.5 are as defined above or C.sub.1 to C.sub.4 alkyl;
• and
• M is a divalent metal selected from Ca, Cu, Zn, Mn, Fe, Co, Ni and Ba.