Elastic cover for printing head nozzles - comprises EPR or EPDM compsn. contg. hydrophilic additive to promote wettability of nozzle

摘要

A elastic cover for closing nozzle openings of a writing head filled with an aq. liq. comprises a viscoelastic, elastomeric material (I) which fills up the smallest spaces and voids in area of nozzle opening. (I) is a non-polar rubber which contains a hydrophilic additive (II) in addition to curing additives such as peroxide (40%), activator e.g. trialkyl cyanurate, opt. filler and an aging stabiliser. (II) promotes the wettability of (I) with the ink so that after removal of the cover, ink remains on the surface and dirt is removed. (II) dissolves thickened ink residues and the material can absorb them. The cover maintains its hydrophilic properties even after prolonged use since (II) migrates to the surface.