Crosslinking of XNBR with polyvalent epoxy compounds (PECs) for accelerator-free rubber films

The serious problems of skin inflammations (dermatitides) observed in the users of rubber gloves caused by type I or type IV hypersensitivity strongly require their new manufacturing methods free from these irritations. This paper reports our novel approach to the production of rubber gloves addressing these problems. A synthetic rubber latex, carboxylated nitrile butadiene rubber (XNBR), was crosslinked using polyvalent epoxy compounds (PECs) without the utilization of accelerators that cause those dermatitides. Although epoxy compounds are generally hydrolyzable in alkaline latex solution, optimally hydrophobic PECs, especially a PEC with three epoxy groups derived from trimethylolpropane, were found to be effective crosslinking reagents for producing high performance XNBR films. The methyl isobutyl ketone (MIBK)-water partition coefficient is an advantageous index to select suitable PECs in this process. The XNBR film produced by the PEC from trimethylolpropane had a high durability to simulated perspiration liquid and the pot-life of the mixed latex solution was longer than 7 days. The XNBR films produced by our novel process that contain no substances causing type I and type IV hypersensitivity are potentially free from the skin inflammations.