Influences of probe shape and surface roughness on tack properties measured by the probe tack test and characterization of crosslinked polyacrylic pressure‐sensitive adhesives

Abstract

For a probe tack test for a pressure-sensitive adhesive (PSA) under the conditions of light contact pressure and short contact time, probes with shapes and surface roughnesses suitable to achieve better wettability were investigated.A smooth, polished probe that became slightly convex at its center was found to be superior to flat-ended. High surface roughness decreased tack. Debonding observations showed that fibrillation started from the probe edge and extended to the center. The fibril grew, without peeling, until the peak of the forcedisplacement curve was reached. After the peak, the fibril growth and peeling advanced simultaneously. The fibrillation was important to tack development. The test conditions necessary to observe the deformation behavior of PSA tape with sufficient interfacial adhesion were investigated. The system was preheated at 60 C for 1 h after the probe and PSA tape contacted each other, and was then cooled. The PSA performance of crosslinked random copolymers poly(n-butyl acrylate-acrylic acid) (A) and poly(2-ethylhexyl acrylate-acrylic acid) (B) were compared. A shoulder formed by fibrillation after the peak in the forcedisplacement curve was observed only for B. Copolymer B exhibited better interfacial adhesion and deformability. The preheating method was found to be useful for characterizing PSAs.

Stringiness morphology for crosslinked polyacrylic pressure‐sensitive adhesives measured by peel testing with constant rate

“…The surface roughness of the adherends was measured using a confocal laser scanning microscope (LEXT OLS-4000, Olympus, Tokyo, Japan) with a robust Gaussian filter (250 μm cutoff) in the range of a 0.65 Â 0.65 mm 2 in the same way as our previous report. 15 It was shown by an arithmetical mean height (S a ). The arithmetical mean height of a line (R a ) is commonly using as an index of surface roughness.…”

“…Plates (50 mm × 100 mm × 2 mm) of poly(methyl methacrylate) (PMMA), polycarbonate (PC), and fused quartz (quartz), all received from Engineering Test Service Co., Ltd., Osaka, Japan, were used as adherends. The surface roughness of the adherends was measured using a confocal laser scanning microscope (LEXT OLS‐4000, Olympus, Tokyo, Japan) with a robust Gaussian filter (250 μm cutoff) in the range of a 0.65 × 0.65 mm 2 in the same way as our previous report 15 . It was shown by an arithmetical mean height ( S a ).…”

“…There are many researches to raise the fracture energy of tack by the stringiness of PSA 6–13 . We also investigated the effect of stringiness for tack under the test condition close to the ASTM standard 14,15 …”

“…[6][7][8][9][10][11][12][13] We also investigated the effect of stringiness for tack under the test condition close to the ASTM standard. 14,15 The stringiness can also be seen by the observation of the peeling of PSA from the side during the peel test. As mentioned above, the absorption of applied stress by stringiness is expected, there has been much research on stringiness behavior and its relation with the peel strength has been discussed.…”