3 Terms and definitions

The following terms and definitions apply to this document.

3.1 Test strips of release film
Test strips taken from a batch of release film materials and representing the performance of the entire batch of release film.

3.2 Test pressure-sensitive adhesive tapes
Pressure-sensitive adhesive tapes with a certain width, thickness and adhesion used for the 180° peel test of release film.

3.3 Test strips for release force
Test strips for release film after lamination of release film test strips and test pressure-sensitive tape for 180° peel test.

3.4 Control strips
Test strips for release film after flat lamination with a typical support without special treatment for 180° peel test.

3.5 Test strips for subsequent adhesion
After the release test strips are adjusted, the pressure-sensitive adhesive tape for testing is completely separated from the release film and flatly laminated with a typical support without special treatment (the same as the typical support in 3.4) to be used for the 180° peeling test.

3.6 Peeling test at 180 angle
The load required to continuously peel a test strip of a certain width at a certain speed under the peeling condition of a peeling angle of 180°. It is expressed in mN/25mm.

3.7 Subsequent adhesion
The ratio of the 180° peeling test of the above-mentioned residual adhesion strips to the 180° peeling test of the control strips.

4 Principle

The strips are peeled at a constant speed of 180° along the longitudinal axis of the strips, and the 180° peeling test of different types of strips is measured during this process, so as to obtain the 180° peeling test of the release film and the residual adhesion rate of the release film calculated according to the formula.

5 Test equipment

5.1 Pressing roller
The pressing roller conforms to GB/T2792.

5.2 Test plate
The test plate conforming to GB/T2792 shall be used. The material can be OCr18Ni9 or 1Cr18Ni9Ti stainless steel sheet, or thin sheet made of polyethylene terephthalate (PET), polyvinyl cyanide (PVC), butadiene acrylonitrile styrene copolymer (ABS), etc. The material and surface condition of the test plate shall be stated in the test report.

5.3 Length gauge
The measurement accuracy is ±0.5mm.

5.4 Specimen cutter
The appropriate tool for cutting specimens, such as paper cutter, cutter, surgical knife, etc.

5.5 Tensile testing machine
The tensile testing machine shall make the breaking load of the specimen between 15% and 85% of the full load. The error of the force indication shall not be greater than 1%. The test machine can continuously peel at a rising speed of 300mm/min ± 10mm/min or a suitable speed, and can automatically record the relevant displacement and load.

6 Splines

6.1 Shape and size
The splines are long strips with parallel longitudinal sides, a specimen width of 25mm± 0.5mm, and a length of at least 150mm.

6.2 Quantity
The number of each type of splines is not less than 5.

6.3 Preparation

6.3.1 Release film splines
When measuring the 180° peel teste and residual adhesion rate of release films, it is very important that the evaluated samples can produce the average effect obtained by users when using them. Samples should be stored under the conditions recommended by the manufacturer before evaluation to ensure the performance indicators of the product during normal storage and use. The basic goal of the sample selection and storage described above is to ensure that the performance of the measured film material is representative.
Release film splines can be prepared according to the sampling area, the width of the pressure-sensitive tape used for testing, and the number of test splines required.

6.3.2 Release test strips

6.3.2.1 Cut representative release film strips. Stick a 25mm wide test pressure-sensitive tape on the release film strips. Roll back and forth twice with a roller at a speed of about 10mm/s.
6.3.2.2 Press the strips at 23℃±2℃ and 70g/cm3 for 20h to ensure good contact between the release film release material and the test tape adhesive. If necessary, the strips can be directly pressed at 70℃±2℃ and 70g/cm2 for 20h for accelerated aging test, but special instructions should be given.

6.3.3 Control tape strips
The test pressure-sensitive tape is evenly attached to the typical support layer without special treatment, and rolled back and forth twice with a roller at a speed of about 10mm/s.

6.3.4 Residual Adhesive Strips
Completely peel off the pressure-sensitive tape used for testing from the release test strips that have been pressed and conditioned at a temperature of 23℃±2℃ and a pressure of 70g/cm2, and then flatly laminate them to a typical support layer without special treatment, and roll them back and forth twice with a roller at a speed of about 10mm/s.

7 Conditioning and Test Environment

7.1 Conditioning
According to GB/T2918, combined with the release film test conditions, different strips need to be conditioned at a certain temperature and time after the pressure of 70g/cm2 is released.
7.1.1 Release Test Strips
Should be conditioned at a temperature of 23℃±2℃ and a relative humidity of 50%±5% for 4h~4.5h.
7.1.2 Control Strip Strips
Should be conditioned at a temperature of 23℃±2℃ and a relative humidity of 50%±5% for 30min-40min.
7.1.3 Residual Adhesion Specimens
Should be conditioned for 30min-40min at a temperature of 23℃±2℃ and a relative humidity of 50%±5%.
7.2 Test Environment
The test environment is 23℃±2℃ and 50%±5% relative humidity.

8 Test Steps

8.1 Specimen Fixation
Put the test plate in the lower fixture of the tensile tester, adhere ordinary double-sided pressure-sensitive tape to the test plate, and then adhere the specimen to be tested to it to ensure that the peeling is at an angle of 180°.
8.2 Specimen Connection
Put a typical support without special treatment in the upper fixture of the test machine, uncover the lower corner of the test pressure-sensitive tape fixed on the specimen on the test plate to an appropriate length, so that the typical support and the test pressure-sensitive tape are adhered with appropriate pressure.
8.3 Test Speed
Perform the peeling test at a speed of 300mm/min, and record the peeling test value of the measured specimen. Expressed in mN/25mm.

9 Result calculation and expression

9.1 180° peeling test of release film
The average value of the peeling test of all release test strips is the 180° peeling test of the release film.
9.2 Calculation of residual adhesion rate
Calculate according to formula (1):
Residual adhesion rate = 180° peeling test of residual adhesive strip/180° peeling test of control strip*100% (1)
Retain three significant figures.
Among them, the 180° peeling force of the residual adhesive strip is the average value of the peeling test of all residual adhesive strips;
The 180° peeling test of the control strip is the average value of the peeling test of all control strips.

10 Test report

The test report shall include the following:
a) Complete identification of the test material required, including type, source, manufacturer code, model, basic dimensions, and previous history;
b) Description of the pressure-sensitive tape used for the test, including type, source, manufacturer’s brand, batch, lot number, etc.;
c) Sample preparation;
d) Number of samples;
e) Condition adjustment and test environment;
f) Condition of the tensile testing machine;
g) Details of the test plate;
h) Test speed;
i) Test results and calculation methods;
j) Description of whether the sample was discarded or replaced and the reason;
k) Test date.