2013 Volume 49 Issue 2 Pages 50-55
In order to clarify the influences of backing and adhesive thicknesses on tack, thetack of acrylic block copolymer was measured using aprobe tack tester and polyethyleneterephthalate backing with various thickness in the range from 25 to 75μm. For this purpose, three model adhesives were prepared:polymethylmethacrylate-block-polybutylacrylate-block-polymethylmethacrylate triblock(A), polymethylmethacrylate-block-polybutylacrylate diblock added triblock(B) and polybutylacrylate oligomer added triblock(C). From the contact time dependence of tack, the slightly higher tack was obtained at the backing thickness of 38μm for A and at that of 50μm for B and C. The lowest tack was obtained at that of 25μm for all. The shape of stress-time curve measured by a probe tack test was strongly dependent on the backing thickness. Tack was lowest for glass as undeformable backing. There is most suitable backing thickness in each adhesive for improving tack dependent on the elastic modulus of adhesive. The adhesive thickness was varied in the range from 10 to 200μm. The tack rose with the increase in adhesive thickness for all adhesives. The tack rose rapidly below about 30μm thickness and gradually more than it with an increase of adhesive thickness.
