Rolling ball tack test

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. 

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... 

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. 

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. 

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.

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 ...

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. 

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. 

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... 

For adhesive layers whose tack is not too low, the rolling ball tack method may be used [66]. In accordance with PSTC-6, a steel ball of defined diameter is rolled down an inclined plane at a certain tilt angle on to the adhesive test strip, as shown in Fig. 8-19. The distance traveled before the ball stops is a measure of the tack. 

Fig. 2. Tack tests and results, (a) Probe tack, (b) Probe tack vs. temperature for a natural rubber PSA. (c) Loop tack, (d) Rolling ball.

The methods to evaluate PSAs include the rolling ball test (ASTM D3121, PSTC-6, BS EN 1721), loop tack test (ASTM D6195, FINAT Test Method 9, BS EN 1719), and quick stick test (PSTC-S). ... 

D 3121 Test Method for Tack of Pressure Sensitive Adhesives by Rolling Ball... 

ASTM D3121 -94 (1999) Standard test method for tack of pressure-sensitive adhesives by rolling ball. 

The rolling ball test for tack usually involves allowing a stainless steel ball, diameter c. 12 mm, (or sometimes a table-tennis ball) to accelerate down a ramp of fixed (21.5°) inclination on to the horizontal adhesive surface. The distance travelled by the ball on the adhesive surface before arrest is taken as an inverse of tack for that surface. For a given adhesive, the ratio is often found to be constant, where h is ramp height and... 

Pressure Sensitive Tadc of Adhesives Using an Inverted Probe Machine, Test for (D 2979) Tack of Pressure-Sensitive Adhesives by Rolling Ball, Tbst for [Pg.790]

In contrast to the other tack measurement methods mentioned above, the rolling ball test requires simple equipment and is easy to carry out. The main difference to the other tack measurement methods is the fact that the rolling ball method does not measure force. The meaningfulness of the method is also impaired by the following characteristics ... 

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