Estimation of viscoelastic resistance and subduction profile of acrylic based pressure sensitive adhesive sheet subjected to wedge indentation

Abstract

This paper aims to estimate the indentation resistance and deformation shape of a 0.5mm thickness acrylic Pressure Sensitive Adhesive (PSA) sheet subjected to a wedge indentation. As for the effect of apex angle of a wedge blade on the cutting characteristics of the PSA sheet, a 60° wedge blade was mainly investigated through experiments and numerical simulations, while the wedge angles of 42, 16° were discussed with respect to the subduction profile of wedged surface. For the sake of development of PSA deformation model, the Prony series based viscoelastic properties were determined by the shear stress relaxation test. Also, the equivalent Young's modulus was estimated by comparing with an out-of-plane compressive experiment and a Finite Element Method (FEM) based compressive simulation. Through the experimental wedge indentation using the 60° wedge blade, three stages of cutting load response were detected: (1) an exponential response, (2) an extremely increasing response based on the saturated inclined angle of subduction zone, and (3) a saturated gradient for the final stage. Furthermore, it was clarified that the proposed FEM model of viscoelastic-deformable sheet subjected to the 60° wedge indentation was applicable for simulating the cutting deformation for the early stage less than 60% of the thickness. The simulated inclined angle of subduction zone tended to be linearly increased with the indentation depth up to a certain extent, whereas the experimental inclined angle saturated to a constant for the indentation depth larger than 70% of the thickness. One of the reasons why the experimental cutting force was higher than the simulated result was explained as the wetting spreading effect due to the yield flow of PSA sheet. In the latter stage of indentation, the correlation between the mismatching of cutting line force and the mismatching of inclined angle of subduction zone was revealed.temperature of the substrate. The PSA can be classified from the aspects of the physical and chemical composition, i.e. the main elastomer used in the adhesive formulation is such as acrylic, styrenic block copolymers, natural rubber and silicone. The acrylic based PSA is acrylic esters that is yield soft and tacky polymers having the low glass transition temperature. Generalized acrylic PSAs are composed of 50~98 % main monomer, 10~40 % modifying monomer, and 0.5~20 % monomer with functional groups (Satas, 1999). They have many applications spread in various fields, from a specific to common usage. They are applied to self-adhesive labels, protective films, sign and marking films.When the wedge cutting is applied to a laminated sheet which has a PSA in the intermediate layer, various troubles sometimes occur. As for real jamming, there are several reasons by being wet on the blade, detaching/peeling of the end of sheared section and flowing out from the sheared section. The jamming phenomena are not revealed sufficiently, while many actual troubles are empirically taken by the hand operation of experts. In order to predi...

Wedge indentation characteristics of pressure-sensitive adhesives sandwiched by polyethylene terephthalate films

“…From the out-of-plane compressive tests, the elastic modulus of the PSA film was estimated at 0.7 MPa (Kaneko and Nagasawa, 2019). The PSA exhibited extremely low stiffness, especially when compared with that of the PET film.…”

“…Namely, it is estimated from the instantaneous elastic modulus, E0, and the Poisson's ratio, ν. Table 3 shows the relaxation properties obtained from a shear stress relaxation test when the shear strain was γ0= 40% (Kaneko and Nagasawa, 2019). The static-elastic modulus assumed that the instantaneous elastic modulus was E0=0.7 MPa and the Poisson's ratio was ν=0.49.…”

“…The static-elastic modulus assumed that the instantaneous elastic modulus was E0=0.7 MPa and the Poisson's ratio was ν=0.49. These were estimated from the out-of-plane compressive tests previously published by other authors (Kaneko and Nagasawa, 2019). experienced warpage during the cutting process.…”