Curing system Soap/sulfur

Resin-curing systems Soap/sulfur systems Urethane crosslinking agents Bisphenol curing agents... 

Because of the different vulcanization chemistry involved in each commercial ACM, a vulcanization system specific to the cure site present has to be adopted. Many cure systems for labile chlorine containing ACM have been proposed (45). Among these the alkali metal carboxylate—sulfur cure system, or soap—sulfur as it is called in the United States, became the mainstay of acryflc elastomer technology in the early 1960s (46), and continues to be widely used. 

The original, and currently extensively used, cure-site group is chlorine based. A number of cure systems may be used, but the most common is the soap-sulfur one using sodium and potassium stearate with sulfur or a sulfur donor. Very good physical properties and heat resistance may be obtained with the chlorine cure sites, however compression set resistance is only fair. 

One would expect that soap/sulfur, or sulfur donor or triazine cure systems may be used because of the presence of the chlorine cure site, however, the shelf stability is only fair and the cure rates are slow. The physical properties, heat aging and compression set obtained are good with the soap/sulfur combinalion but better properties may be obtained with other curatives such as NPC, hence these are not recommended. Diak 3 gives properties similar to those of the soap/sulfur system, but has the added disadvantage of a poor compression set and a higher hardness. 

Naugard 445 is also the recommended antioxidant for imparting the best high temperature resistance in ACM. Various antioxidant synergists were compared to supplement the performance of Naugard 445. They included a phosphite (Naugard P), a toluimidazole (ZMTI), a thioester, and sodium ethyUiexyl sulfate in either a trithiocyanurate or a soap/sulfur cure system. 

---