Encapsulating compositions

An improved curable composition suitable for the encapsulation of electronic devices, said composition comprising a curable epoxy resin and, as the improvement therefor, from 0.5 to 10 percent by weight of a metal ion scavenger effective in reducing the level of metal ion or chloride ion or both metal ion and chloride ion extractables from said composition, said metal ion scavenger selected from the group consisting of

• (A) Calixarene or oxacalixarene derivatives represented by the formula ##STR21## wherein m'+m"=0-8;
• n=0-8;
• m'.gtoreq.1/2(m'+m");
• .ltoreq. m'+m"+n.ltoreq.8;
• if n=0, m'+m".gtoreq.4;
• the R.sup.3 groups are the same or different and are H, halogen, or hydrocarbyl or a substituted derivative thereof;
• R.sup.4 is hydrocarbyl, hydrocarbyloxy or a substituted derivative thereof;
• or R.sup.4 is ##STR22## wherein R.sup.5 and R.sup.6 are the same or different and are H or hydrocarbyl or a substituted derivative thereof;
• R.sup.15 is H or hydrocarbyl or a substituted derivative thereof;
• the calixarene or oxacalixarene derivative being present as a compound per se or being bound into the polymer network of the polymeric material;
• (B) Silacrowns represented by the formula ##STR23## wherein R.sup.7 and R.sup.8 are the same or different and are hydrocarbyl, hydrocarbyloxy, or a nitrogen-substituted or other substituted derivative thereof;
• z is 3-6;
• and
• (C) polyalkylene ether derivatives represented by the formulae ##STR24## wherein R.sup.12 is --(R.sup.10 --O).sub.q --R.sup.11 ;
• q is an integer of from 2 to 25;
• R.sup.10 is a substituted or unsubstituted alkyl residue having 2 to 6 carbon atoms, the (R.sup.10 --O) groups containing the same alkyl residue or containing different alkyl residues distributed on the chain in a random or block manner;
• R.sup.11 is hydrogen, hydrocarbyl or a substituted derivative thereof;
• R.sup.13 is hydrogen, halogen, or hydrocarbyl or a substituted derivative thereof;
• and
• x is an integer from 4 to 8.