Лако-красочные материалы — производство

These two-part powder/liquid materials, close relatives of the ZOE cements, in the ulti­mate form are zinc chelates, resulting for the most part from reaction of ZnO with ortho — ethoxybenzoic acid:

The zinc oxide-ethoxybenzoic acid (EBA) cements can thus be classified as zinc carbox — ylates in which the metal center is additionally bonded coordinatively to two ether oxygen atoms, forming electronically stabilized six-membered chelate ring structures. The powder component, again, contains zinc oxide, typically 60%, in addition to some 35% fused quartz filler and other resin ingredients, whereas the liquid part may typically consist of a 60:40 mixture of ethoxybenzoic acid and eugenol. Hence Zn eugenolate chelates are pre­sent as well in the hardened matrix. As with the ZOE materials, and much to the con­venience of the clinician, the setting is accelerated by moisture in the oral environment. The hardened cement is comparatively strong under compressive load, ultimate compres­sive strength values reaching 80 to 85 MPa; in addition, it is less soluble than the ZOE cements in water. Both factors combine to render the EBA materials suitable for perma­nent luting.