Crosslinking Of Carboxylated Nitrile Rubbers With Resol Resins

This paper discusses at length the metal oxide and sulfur-free crosslinking of rubber compounds for carboxylated nitrile rubber (XNBR ) using resols based on p-alkyl phenols ("resol crosslinking").

 

It demonstrates that, with the right grade and dosage of resol and the right Krynac® X nitrile rubber grade, the property profile resulting from traditional crosslinking with zinc oxide/sulfur can be altered and significant improvements achieved in terms of processing properties and, for instance, the compression set characteristics.

 

Resol crosslinking is heavily dependent on the grade of rubber used. The best and most balanced property profile can be achieved with XNBR grades containing 1 % carboxylic acid (Krynac® X 146, Krynac®X 160).

When the principles explained in this text are observed, vulcanizates based on XNBR grades containing 7 % carboxylic acid (Krynac® X 750) also offer advantages. 

 

In addition to vulcanizates containing carbon black, the paper looks at compounds containing silica and shows that, in this case, the additional use of silanes is indispensable for effective vulcanization.