Standard Test Method for Unwind Force of Pressure-Sensitive Tapes

 

Theory:

ASTM D3811 characterizes a test for measuring the peak force needed to unwind a roll of pressure-sensitive adhesive (PSA) tape. The procedure is intended to simulate unwind tape either with a human hand, or with a tool or machine. This test is similar to ASTM D1000, however it is much simpler and designed to unroll the tape at low speeds. Several outer layers of tape should be unwound and discarded before beginning this test. 

 

Geometry:

Rolls of tape are tested at a standard 1 inch thickness. The roll should be of consistent width throught the test. About a half of one foot of tape should be unwound during the test. 

Solution:

A freely rotating spindle grip must be used to hold the tape roll. The spindle is used in combination with a vise grip or similar type of tensile grip. The roll of tape should fit appropriately onto the spindle and it should be able to turn freely. The vise grip could have a few different types of grip faces with the rubber grip inserts being the most common. 

Analysis:

The unwind force is given by the peak load seen during the test. In most samples of tape rolls, this occurs towards the beginning of the test, however this is not always the case. The tabulated reports are usually delineated in lbf/in. The average peel force can also be measured and analyzed. Most operators will ignore the first few inches and last few inches of tape and only take the data from the middle as is common with most peel tests. 

ASTM D3811

Tape Roll Unwind Test