Study of scavengers for free formaldehyde reduction in phenolic resins used in polychloroprene based contact adhesives

The objective of the study was to identify, analyze suitable scavengers for the free formaldehyde in phenolic resins used in polychloroprene based contact adhesives; as formaldehyde is a known CMR (carcinogenic, mutagenic, reprotoxic) agent. Phenolic resins used in the manufacture of adhesives inherently have formaldehyde which is trapped during synthesis. This study was carried out to reduce this to non-detectable levels of free formaldehyde. Sodium sulphite and sodium metabisulphite were used as scavengers to reduce free formaldehyde content. The reactions and mechanisms of the quenching was studied, to finalize the most suitable and feasible scavengers. Stages of addition of the identified scavenger during formulation of contact adhesives were done so that efficiency in reduction is maximum. Formulated adhesive was evaluated for applications and performance tests like peel strength and heat resistance in comparison with a control and it was found that scavenger addition (sodium sulphite and sodium metabisulphite) does not affect adhesives performance.