The initial tack test of products such as pressure-sensitive adhesive protective film and tape was carried out in accordance with the National Standard GB/T4852-2002 of the People's Republic of China.
1 Fundamental Concept
When the object and the glued surface of pressure-sensitive adhesive protective film are contacted with a small pressure for a short time, the adhesion effect of the protective film on the object is called initial tackiness.
1.2 Mission Reason
Roll a steel ball over the adhesive side of the protective film that is placed flat on the sloping plate. The initial tack size can be evaluated based on the maximum steel ball size, which can be adhered to the adhesive face within the specified length.
1.3 Instrument construction
1.3.1 Bevel ball installation: This installation is mainly composed of a sloping plate, a ball arranging device, a bracket, a base and a ball receiving box.
1.3.2 Steel ball: 32 kinds of steel balls made of GCr15 bearing steel with a precision of not less than the standard of GB 308-77 "Steel Ball" and diameter of 1/32 inch ~ 1 inch, can be used as test steel ball.
Each steel ball is arranged according to 32 times its inch diameter. A set of steel balls continued by the ball number should be used for the test.
Steel balls should be stored in anti-rust oil. Balls with rust and scars must be changed in time.
1.4 Skill goal
Adjustable tilt angle: 0～60°
Table width: 120mm
Test area width: 80mm
Specification steel ball: 1/32" to 1"
Dimensions: 320 (L) mm × 140 (B) mm × 180 (H) mm
2 Operation Method
2.1 Preparatory tasks
2.1.1 Adjust the bevel ball installation to the degree of position, except for the rule, adjust the inclination of the inclined plate to 30°.
2.1.2 Use an absorbent gauze with a cleaning agent to scrub the glass exterior and the both sides of polyester film, and then clean them with gauze.
2.1.3 Wipe anti-rust oil off the steel ball and soak it in a container containing detergent for a few minutes. Get the ball out and clean it with a clean detergent and gauze, then wipe it clean with a clean gauze. After cleaning, use a clean bamboo (wood, bone) or other things to get the ball.
2.1.4 Place the protective film sample on the inclined plate with the adhesive side facing up. A polyester film is applied to the specified position as a roll-up section. The roll-up section should be flat and free from defects such as air bubbles and wrinkles. The 100mm below the roll-up section is limited to the test section.
2.1.5 Use adhesive tape to fix both sides of the roll-up section and the lower end of the sample to the inclined plate. If necessary, use adhesive tape to fix the edges of the test section so that the sample fits flat on the board.
2.1.6 Use a pair of tweezers to clamp the steel ball into the ball ejector, and adjust the front and rear position of the ball ejector so that the middle of the steel ball is at the beginning of the roll-up section. Before the formal test, use a sample for repeated tests, but the left and right position of the ball ejector should be adjusted so that the trajectory of the steel ball does not coincide. When the width of the sample is larger than 25 mm, the area of 25 mm wide at the center of the sample is a useful test area.
2.2 Preselection of the largest steel ball
2.2.1 Open the ball ejector quietly and see if the rolled steel ball can be stuck in the test section (stop moving for less than 5s). From large to small, take steel balls with different continuous ball numbers for proper testing until you find the largest ball that can be stuck in the test section.
2.2.2 Take the above-mentioned largest ball and the two balls next to it, and perform a test on the unified sample to confirm the steel ball of the largest ball number.
2.3 Formal testing
Take 3 samples and perform a ball test with each of the largest steel balls. If a steel ball doesn't stick on the protective film, replace this ball with a ball that is only smaller. If it still cannot be stuck, it must be tested again according to 2.1.4~2.3.
3 Experimental results
3.1 Analyze the performance of the steel balls after the test.
3.2 Among the three steel balls that can stick on the protective film, if all three are the largest steel balls or perhaps two are the largest steel balls, and the third one is only smaller than the largest steel balls, the test result is based on the maximum ball number. If one is the largest steel ball and the other two steel balls are only smaller than the maximum ball number, the test result is based on the steel ball number only smaller than the largest ball.