Foam stabilizing composition for fluorine-free firefighting foams

A foam stabilizing composition, comprising:

• (A) an anionic polymer;
• and
• (B) a siloxane cationic surfactant having general formula (I):
• [Z1-D1-N(Y)a(R)2-a]+y[X−x]n (I),
• wherein Z1 is a siloxane moiety;
• D1 is a divalent linking group;
• R is H or an unsubstituted hydrocarbyl group having from 1 to 4 carbon atoms;
• each Y has formula -D-NR13+, where D is a divalent linking group and each R1 is independently an unsubstituted hydrocarbyl group having from 1 to 4 carbon atoms;
• subscript a is 1 or 2;
• 1≤y≤3;
• X is an anion;
• subscript n is 1, 2, or 3;
• and 1≤x≤3, with the proviso that (x*n)=y;
• wherein at least one of the following provisos is true:
• (i) components (A) and (B) are present in the foam stabilizing composition in a weight ratio of from 0.5:1 to 3.5:1 (A)/(B);
• and/or
• (ii) components (A) and (B) are present in the foam stabilizing composition to provide a molar ratio of anionic groups in component (A) to cationic groups in component (B) of from 1:1 to 6.5:1;
• wherein component (A) is selected from sodium carboxy methyl cellulose, propylene glycol alginate, poly-D-galacturonic acid and its methyl ester, carboxymethyl dextran (sodium salt), and combinations thereof.