Ethoxy benzoic acid increases the strength and solubility of the cement:

Modifications have been made to improve the strength and abrasion resistance of  ZOE cement for long-term luting. One system substitutes orthoethoxybenzoic acid (EBA) for part of the eugenol liquid, and includes alumina in the powder. Another system (ZOE plus polymer) consists of eugenol liquid and a special powder containing of 20%  to 40% by weight of fine polymer particles and zinc oxide particles that have been surface treated with carboxylic acid. Phillips 12 ed pg 331