GB/T 25256-2026Optical functional films - Test method for the 180° peel force and subsequent adhesion of release films (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document replaces GB/T 25256-2010 "Test Method for 180° Peel Strength and Residual Adhesion of Optical Functional Thin Film Release Films", and is consistent with... Compared with GB/T 25256-2010, apart from structural adjustments and editorial changes, the main technical changes are as follows:

a) Added the 180° peel test principle for release test strips, and the 180° peel test principle for control strip strips and residual adhesion strips (see...). Chapter 4);

b) The phrase "The pressure roller is a cylindrical steel pressure roller conforming to

5.3.4 of GB/T 2792-2014" was changed, and "its diameter is..." was added. (85.0±2.5)mm, with a surface covered by approximately 6mm thick rubber. The rubber hardness is (80±5) Shore A, with no unevenness or deviation. The amount is (2000±100)g (see 5.1,.2010 edition 5.1);

c) A requirement for a "sample preparation plate/platform" has been added (see 5.2);

d) The phrase "The test plate may be a thin stainless steel sheet conforming to

5.3.3 of GB/T 2792-2014" was changed, and "of which stainless steel..." was added. The steel sheet should be flat, smooth, bright, clean, and free of stains and scratches (see 5.3,

5.2 of the.2010 edition);

e) The requirements for tensile testing machines have been changed (see 5.6,

5.5 in the.2010 edition);

f) Added content and illustrations regarding the preparation of release test specimens on a sample preparation plate/platform (see 6.3.2.1);

g) The requirement that "the spline should be flat, without wrinkles, and without air bubbles" has been added (see 6.3.2.1, 6.3.3, and 6.3.4);

h) Added the content "Select an appropriate tension sensor with maximum load" (see 8.1);

1 Scope

GB/T 25256-2026 is the Chinese national standard covering the release liner on an optical film - it must come off cleanly at a controlled force and must not leave silicone behind, because whatever it leaves is then bonded into a display. It replaces GB/T 25256-2010 and has been in force since 1 October 2026. It was issued on 31 March 2026 and takes effect on 1 October 2026, replacing GB/T 25256-2010. The document is under the responsibility of the China Petroleum and Chemical Industry Federation. This page is published from the official record of the 2026 edition; the clause text of a standard this recent is not yet in circulation, and the figures, limits and tables it contains are those of the document itself, delivered in full with the English translation.

This document describes the test methods for the 180° peel force and residual adhesion rate of the release film. This document applies to the testing of 180° peel force and residual adhesion of release films with plastic substrates.

4 Principles

4.1 Principle of 180° Peel Test of Release Test Strip Peel the sample at a constant speed of 180° along the longitudinal main axis and measure the 180° peel force of the release test sample during this process, as shown in Figure 1.

4.2 Principle of 180° peel test for control strip and residual adhesive strip Peel the sample at a constant speed of 180° along its longitudinal main axis. Measure the 180° peel force controlling the strip and residual adhesive strip during this process, as shown in Figure 2. As shown.

5 Experimental Apparatus

5.1 Pressure Roller The pressure roller is a cylindrical steel pressure roller conforming to

5.3.4 of GB/T 2792-2014, with a diameter of (85.0±2.5) mm and a surface coating. It is covered with rubber about 6mm thick, the rubber hardness is (80±5) Shore A, there is no unevenness, and the mass is (2000±100)g.

5.2 Sample preparation plate/platform During sample preparation, to ensure that the pressure-sensitive tape used for testing adheres tightly to the release film sample and the typical support, it should be placed on a horizontal, smooth, rigid surface. Sample preparation is carried out on a plate or platform, which can be made of smooth float glass, smooth stainless steel, etc.

6 Test specimens

6.1 Shape and Size The sample is long and parallel on both sides, with a width of (25.0±0.5) mm and a length of not less than 150 mm.

6.2 Quantity There should be no fewer than 5 of each type of spline.

8 Test Procedure

8.1 Select an appropriate tension sensor with maximum load. Select a suitable tensile sensor based on the peel force range of the tested sample.

9 Calculation and Representation of Results

9.1 Release film 180° peel force The arithmetic mean of the peel force values of all release test specimens is the 180° peel force of the release film. Significant figures are rounded to one decimal place.

9.2 Calculation of Residual Adhesion Rate Calculate according to formula (1), and retain one significant figure after the decimal point.

10 Test Report The test report should include the following.

a) Complete identification of the required test materials, including type, source, manufacturer code, model, basic dimensions, and previous history;

b) Specifications of the pressure-sensitive adhesive tape used for testing, including type, source, manufacturer's brand, batch, lot number, etc.

c) Sample preparation details;

d) Number of samples;

e) Conditioning and test environment;

f) The condition of the tensile testing machine;

g) The material and surface condition of the test plate;

i) Experimental results and calculation methods;

j) A description of whether any samples were discarded or replaced, and the reasons therefor;

k) Trial date. GB/T 25256-2026. Test method for 180° peel strength and residual adhesion of optical functional thin film release film ICS

15 National Standards of the People's Republic of China Replaces GB/T 25256-2010 180° peel strength of optical functional film release film and Residual adhesion rate test method Published on 2026-03-