Details:
Summary:
In order to clarify the relation between the gelled structure in varnish, rheological properties and printability, dynamics and rheological properties were examined for two kinds of varnishes which are prepared by chemically gelled binder and physical one. Rheological properties such as dynamic viscoelastic properties and flow properties were measured using cone and plate rheometer. Dynamic behavior of liquid film splitting between rollers were investigated using a video monitoring and an acoustic techniques. The rheological properties of varnish are affected by density of structural networks. The network structure formed by the chelate type gellants is durable and stable under large deformation, therefore, the steady shear viscosity and normal stress of the varnish are extremely large in higher shear region. The varnish having chemically closs-linked bonding shows the large tack value and the longer filamentation. However, the varnish having physically closs-linked networks show the small tack value and the short filament, even though the denser network structure exists initially. The remarkable difference between the varnish having chemically closs-linked bonding and that having physical closs-linked one was observed in the acoustic spectrum.