Relative Performance of Release Coatings

1 4-11. Release force is the measure of the force required to separate a unit width of pressure sensitive tape from a Release liner at controlled angle and speed. Subsequent adhesion is the force required to remove a unit width of pressure sensitive adhesive tape , which has been in contact with a Release liner for a given period of time, from a standard test panel. The results of this test must be compared with the adhesion of the same tape which has not been in contact with the Release liner to determine the degree of loss of The following test is designed to compare two main properties of Release Coatings : 1) Ease of Release (as Release force ), and (2) the effect that the coating has upon the adhesive properties of a pressure sensitive tape that has contacted the Release surface ( subsequent adhesion ).

2 It is designed for use as a tool in determining Relative Release levels and consistency. 3. TEST pressure sensitive tape For conditioning, selection, and test conditions, see Appendices A and The test specimen shall be 24 mm (1 ) wide and approximately 300 mm (12 ) in length. A width tolerance of mm (1/64 ) shall be allowed. Select six specimens and number them 1 through 6. Release coated liner Condition specimens as described in Appendix Randomly select from the liner material to be evaluated, sufficient liner material to provide three 48 mm x 150 mm (2 by 6 ) specimens. Take care not to contaminate the side to be evaluated.

3 4. EQUIPMENT - See Appendix Tensile tester or adhesion/ Release tester. Panels. Roller, 2 kg (4 1/2 lb.), mechanically operated. A roll of pressure sensitive tape , 24 mm (1 ) wide, of a type mutually agreed upon between supplier and user. Because of the differences between tapes, caution should be used when compar-ing values obtained with different test tapes. Only rolls of tape having an adhesion of to Newton/100 mm or equivalent in other units should be used. The test tape should be specified when reporting Performance of Release CoatingsCall Letters PSTC 4 Date of Issuance 03/92 Revised 06/00 Revised 10/03A Summary of Changes section appears at the end of this test Two smooth metal pressure plates and weights sufficient to apply a uniform pressure of kPa (1/4 psi) on the test tape .

4 Aluminum plates, 36 mm (1-1 1/2 ) by 144 mm (6 ) by mm (1/16 ) thick, can be used as the metal pressure plates. The plates must be flat and parallel to a toler-ance of mm ( ). A 24 mm (1 ) by 24 mm (1 ) by 96 mm (4 ) bar weighing kg kg (1 lbs.) placed lengthwise over the center of the pressure plate protecting the samples to be tested will yield the required kPa (1/4 psi). An air circulating oven capable of maintaining a temperature of approximately 70 C (158 F) for 20 hours 1/2 TEST Before each test, clean the panel per method in Appendix Initial adhesion to steel - Using tape specimens marked 1, 3, and 5, touch one end of the speci-men to the end of a test panel, hold the other end of the specimen so that it does not make contact with the panel but is positioned loosely above it.

5 Roll the tape mechanically once in each lengthwise direction causing the roller to apply the tape to the panel. Take care not to entrap air between tape and panel. If such occurs, discard the specimen. Prepare all three specimens and allow to dwell for a minimum of 20 to a maximum of 25 minutes before testing for adhesion as described in Report test results as initial adhesion to Adhesion to liner - Completely cover one side of three panels with liner by first covering the panel with a high adhesion double coated pressure sensitive tape . Firmly apply, wrinkle free and with no air entrapped, the liner specimen taking care not to touch or otherwise contaminate the exposed surface of the liner.

6 This is best accomplished by touching one end of the liner to the tape -coated panel and using the roller to apply the liner to the panel. Trim excess length of liner at each end of the panel. Apply tape specimens 2, 4, and 6 to the liner-covered panels as described in Place specimens in the oven and apply a panel and weight on top of the panel to provide kPa (1/4 psi) and allow to condition for 20 hours 1/2 hour. At the end of 20 hours 1/2 hour, remove the specimens from the oven, remove weight and top panel and condition as described in Appendix A until cooled to room temperature (approximately 1 hour). Test Initial adhesion - Double back the free end of the tape at an angle of 180 and peel 24 mm (1 ) of the tape from the panel at the folded end.

7 When using a tensile testing machine clamp the end of the panel from which the tape was removed into the moving jaw and the free end of the tape into the stationary jaw. The crosshead travel of the tensile testing machine is to be 300 mm/minute (12 /minute). After the moving jaw is started in motion, disregard the values obtained while the first 24 mm (1 ) of tape is mechanically peeled. Record the average adhesion obtained over the next 48 mm (2 ). When using an adhesion/ Release tester, slide the panel under the panel clamps with the free end of the tape away from the force measuring instrument. Clamp the free end of the tape into the jaws and set the speed for 300 mm/minute (12 /minute).

8 After the carriage starts moving, disre-gard the values obtained while the first 24 mm (1 ) of tape is mechanically peeled. Record the average adhesion obtained over the next 48 mm (2 ). See Figure Adhesion to liner - Take the cooled specimens prepared as described in and test as described in Take care in removing the first inch to remove tape from the liner, not liner from the panel (see Figure 2). Report test values as adhesion to liner. Subsequent adhesion to steel - After specimens 2, 4, and 6 have been removed from the liner as described in , apply each strip of tape to a clean steel panel as described in and test as described in Report values as subsequent adhesion to Report all values in Newtons per 100 mm of width or other acceptable units.

9 Metric-English system conversion factors are listed in Appendix F. Report any effect the liner Release coating may have on the tape as a percentage. The percent-age subsequent adhesion is obtained by dividing the subsequent adhesion to steel value by the initial adhesion to steel value and multiplying by method for determining Release characteristics is TAPPI Useful Method 502 and ASTM D 3330 Method OF CHANGESNo changes from the 14th 1. Adhesion/ Release 2. Adhesion to liner testing with tensile testing