Current status of AAC preservatives in New Zealand
J A Butcher
Two types of alkylammonium compounds (AAC) have been approved as commercially acceptable wood preservatives by the NZ Timber Preservation Authority (TPA). They are alkyldimethylbenzyl ammonium chloride and alkyldimethylamine acetate, both of which must contain either (a) 70% alkyl chains of C12 + C14 and less than 10% of any other individual chain length, or (b) 85% alkyl chains of C12 + C14 with no restriction on percentage occurrence of any other chain length. Existing approvals cover formulations of the quaternary ammonium compound and of the tertiary, amine salt. Approvals for use are currently restricted to Pinus radiata and to those commodities which do not involve ground contact. For interior building timbers (Commodity Specification C8), where protection is required only against insects, the minimum charge retentions and core loadings are: Alkyldimethylbenzyl ammonium chloride: 1.5 kg/m³ and 0.1% w/w; Alkyldimethylamine acetate: 1.0 kg/m³ and 0.07% w/w.