Synthesis and characterization of a new adhesion-activator for polymer surface

Abstract

We developed a new type of adhesion-activator, Lichlor-6, consisting of lithium chlorohexylisocyanurate (LCI) and lithium dichloroisocyanurate (LDI), which can be soluble in water very well (more than 30 g/water 100 g), to replace trichloroisocyanuric acid (TCIA) which is only soluble in organic solvent. LDI acts as an adhesion-activator and LCI is used as additive to improve wetting ability of LDI on the polymer surface. The surfaces of styrene-butadiene rubber (SBR) and ethylene vinyl acetate (EVA) were treated with Lichlor-6 solution and bonded together using water-soluble polyurethane adhesive. Contact angle measurements, attenuated total reflectance-FTIR spectroscopy and scanning electron microscopy were carried out to characterize the treated surfaces. Tear resistance was also tested to compare adhesion strengths. After treatment with 16 wt% solution of Lichlor-6, the water contact angles decreased from 89° and 88° to 34° and 36° for SBR and EVA, respectively. The treatment with the higher concentration of Lichlor-6 produced the more marked chemical and morphology modifications on the SBR and EVA surfaces. The increased surface roughness of SBR and EVA caused by the treatment with Lichlor-6 have larger effects on the decrease of the contact angle than chemical modification. Tear resistance values obtained are 4.9, 6.5, 8.4 and 10.2 kgf/2 cm for the treatment with 0, 2, 5 and 8 wt% solutions of Lichlor-6, respectively, and the tested tear resistance is almost inversely proportional to the larger one between the two contact angles of SBR and EVA surfaces.