Rolling ball tack

In another tack test, a steel ball of specified diameter is rolled down a grooved incline onto a conditioned surface area of pressure sensitive adhesive (ASTM D 3121, PSTC-6). The length of travel before it stops is the rolling ball tack (Fig. 2d) reported in millimeters. It is relatively inexpensive and simple to set up. Similar test variables to the probe tack test apply. 

PSA Formulation and Properties. The formulations used in this study for the Hycar 2103-Prepolymer C and Hycar 2106-Prepolymer C PSA contain OH/NCO ratios of 1.7 and 1.3, respectively. Dibutyltin dilaurate catalyst is used at a 0.2 wt.% level based on the total adhesive solids. PSA samples are made from an 80% solids solution (by wt.) with a dry solvent system (27/73 by wt. of ethyl acetate-toluene) and cured at 150°C for 45 seconds. The samples are then evaluated by running 180° peel, static shear, rolling ball tack, and vinyl film shrinkage tests. 

These adhesive systems give an excellent combination of static shear (at both room temperature and 70°C) and rolling ball tack along with excellent vinyl film shrinkage resistance. The results of these tests are summarized in Table III. 

Performance Flexibility. Figure IV illustrates the effect of the 0H/NC0 ratio of 180° peel strength and rolling ball tack for both the Hycar 2103-Prepolymer C and Hycar 2106-Prepolymer C adhesive systems. Peel strength values of 493 N/m (45 oz./in.) or lower are possible for the Hycar 2103 system simply by altering the 0H/NC0 ratio. Likewise for the Hycar 2106 system, peel strengths of 657 N/m (60 oz./in.) or lower are possible. 

In both cases, rolling ball tack remains relatively constant unless the 0H/NC0 ratio becomes too low. In addition, no creep in static shear is observed at room temperature or 70°C at the ratio shown. 

Figure V demonstrates the effect of adhesive dry coating weight on 180° peel strength and rolling ball tack with OH/NCO ratios of 1.7 and 1.3 for Hycar 2103 and Hycar 2106, respectively. Static shear tests run both at room temperature and 70°C show no creep for both systems throughout the thickness range tested.

Only at low adhesive coating weight does the rolling ball tack begin to increase slightly. 

Figure 4 Rolling ball tack testing (a) douglas (b) PSTC (c) dow. 

The classic test for tack of a pressure-sensitive adhesive film is the rolling ball tack test. Here a ball is rolled down an inclined plane onto a film of the adhesive. The length the ball travels across the film before stopping is a measure of the tack of the film. This test gives a good indication of tack with elastomer adhesives but is unreliable with water-based systems. 

Another ASTM standard method, rolling ball tack (12), involves placing a piece of tape, adhesive side up, at the base of an inclined surface. A steel ball is allowed to roll down the incline from a fixed height, and the distance that the ball travels across the adhesive surface of the tape is taken as a tack value. Longer distances of travel indicate that the tape is less tacky. Other tests involving drums, rollers, or loops of tape have also been used, but are not as common. 

Figure 14. Standard test methods fiat the tack of pressure-sensitive adhesive tapes A) Rolling-ball tack B) Rotating-drura tack ...

Fig. 1. Schematic of the different methods for the evaluation of tack properties, (a) Probe tack, (b) Rolling ball tack, (c) Loop tack.

Shear Adhesion Failure Temperature, peel adhesion, and holding power. To restore these properties, high softening point endblock resins were added. Figure 18 summarizes the effects of four such resins in the formulation containing 25 parts of oil (Table 9). Cumar LX-509 resin was selected for use in a final formulation because it had the greatest beneficial effect on shear adhesion failure temperature and showed only moderate loss in rolling ball tack. 

ID No EB Dose, Mrad Gel Content, % Rolling Ball Tack, cm Saft Mylar, °C 95 Holing Power,min 180 Peel, N/m... 

Rolling ball tack is a unique test method in which a small ball of specified weight and diameter is rolled down an incline plane onto an inverted test adhesive strip. The distance the ball rolls before stopping is an measure of the tack properties of the adhesive. 

Although tack testing using a fiat probe (probe tack) is almost universally the choice in scientific literature, industry literature frequently refers to a rolling-ball tack test. 

The rolling ball tack test consists of a ball rolling down an inclined ramp and contacting a firmly held horizontal tape strip butted against... 

Using PSTC Test Method No. 6, rolling ball tack valves for commercial adhesives vary from about 0.1 inch to about 10 inches anything under 1 inch is considered evidence of a tacky PSA. 

Fig. 10. Schematic of PSTC rolling ball tack tester. 1, V-shaped trough 2, release mechanism 3, leveling bubble 4, tape specimen 5, diameter steel ball 6, base curve 7, angle of 21 30. ...

Rolling ball tack tester refer to Fig. 25 and to ASTM standard D 3121. 

Figure 25 Measurement of PSA tack by rolling ball tack tester.

Illustrations of several test methods used to characterize tack of pressure-sensitive adhesives (PSAs) (a) flat probe tack, (b) loop tack, and (c) rolling ball tack... 

Several tack tests, such as probe tack, loop tack, quick stick, and rolling ball tack tests, are used to evaluate the aggressiveness of a polymer surface. 

---