1972 年 21 巻 224 号 p. 392-396
Hereunder is reported the study made of the rheological properties of pressure-sensitive adhesives by measurement of viscosity, Young's modulus, compliance and relaxation modulus, and the discussion made of the relationship between the Theological properties and the tackiness.
The adhesive systems are blends of masticated natural rubber and the pentaerythritol ester of partially hydrogenated rosin.
It is known from observations with an electron microscope and measurements of mechanical loss that the compositions containing no less than 40wt-% resin are homogeneous mixtures, and when the resin concentration exceeds 40 wt-%, the phase separation occurs and the disperse phase is resin containing a small amount of rubber.
The tackiness measured with probe tack tester for a short contact time (0.2sec) takes the maximum value at the 60 wt-% resin concentration and for a longer contact time (2-20sec) takes the maximum value at the 70 wt-%.
While the viscosity and Young's modulus, measured at 20°C, takes the minimum value at the 70 wt-% resin concentration, the instantaneous compliance takes the maximum value at the 60 wt-% and the steady-state compliance takes the maximum value at the 70 wt-%.
When the wettability of adhesive to the adherent therefore reaches the maximum, the maximum in the tackiness is obtained.
The relationship between the tackiness and relaxation spectrum was also made the subject of our discussion.