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Test method for adhesiveness of screen protective film

Apr 05,2021

Source: Link Testing Instruments Co.,Ltd

The screen protective film is usually pasted on the screens of electronic products such as mobile phones and computers. Its function is to protect the screen from water and dust, while preventing fingerprints from remaining on the screen. Its materials usually include PP, PVC, PET and AR.

Because it needs to be pasted on the mobile phone or computer screen, the protective film should have a certain adhesive performance. If the adhesiveness of the screen protector is poor, that is, the adhesion of the screen protector to the screen is low, the protective film may roll up or air bubbles may remain, which not only affects the appearance, but even peels off the screen protector; if the adhesiveness of the protective film is too high. When the screen protective film is removed from the screen after a period of use, some adhesive components will stick to the screen of the mobile phone, which will cause inconvenience to replace the screen protective film later. Therefore, a screen protective film with appropriate adhesiveness can not only protect the screen, but also facilitate the user's replacement.

Test and Tester

The test indicators for the adhesiveness of the screen protection film include primary adhesive strength, last adhesive strength, peel strength, etc. There are no relevant standards for the protection film in China. This article refers to GB/T 2792-2014 "Test Method for Peeling Strength of Adhesive Tapes". Adhesive testing of screen protectors.

  The LTS-05 electronic tensile testing machine independently developed by Link Testing can be used for testing.

Auto Tensile Tester LTS-05

Testing principle: The equipment is equipped with an upper and a lower clamps for holding the sample. The upper clamp can move according to the test speed preset by the equipment, and the lower chuck is fixed. During the test, the two ends of the sample are clamped on the upper and lower clamps, and the two clamps move relative to each other. The force sensor on the upper clamp and the displacement sensor inside the machine will record the changes in the sample in real time. The force value and displacement generated in the process can finally calculate the performance indicators such as the peel force, stretch, tear, and deformation rate of the sample.

Test sample and Test process

Test sample: a certain brand of screen protector.

Experimental procedure:

(1) Cut 5 specimens with a width of 25 mm from the adhesive part of the screen protection film sample.

(2) Remove the protective layer of the sample, and paste the sample in the center of the clean stainless steel plate. Keep the other end of the sample from the stainless steel plate (free end). parallel.

(3) Roll the surface of the sample along the length direction with a roller four times, and then place the sample for 10 minutes.

(4) Clamp the free end of the sample and the stainless steel plate in the upper and lower clamps of the equipment respectively, so that the peeling surface coincides with the center lines of the upper and lower clamps. (If necessary, increase the length of the free end of the sample by means of overlap)

(5) Set the test speed, sample width and other parameter information, click the test option, the test starts, the sample peels off, the device records the force value and curve during the peeling process in real time, and the device automatically calculates the peel strength of the sample after the test is over .

Test results and Analysis

   The peel strength test results of 5 samples cut from the screen protection film samples were 5.758 N/cm, 5.125 N/cm, 5.869 N/cm, 5.334 N/cm, and 5.547 N/cm, respectively.

LTS-05 Auto Tensile Tester can be used for professional testing of the peel strength of the screen protective film. The test results have good repeatability and high accuracy, which can truly reflect the adhesiveness of the screen protector. In addition to the peel strength of the screen protection film, the device can also be used to test the peel strength of flexible plastic packaging composite films, the peel strength of plasters, the heat seal strength of packaging bags, tensile properties, and puncture resistance.

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