GB/T 39935-2021Plastics - Film and sheeting - Determination of blocking resistance (English PDF)

4.1 Principle

Under the condition of 7kPa pressure and constant temperature of 50 degrees C, the plastic film or sheet should be closely attached and kept for at least 24h. If the bonding material is in the distribution

During the separation process, it is damaged or the adhesion force between the surfaces is greater than a specified load, which indicates that the material is adhesion.

The test time, temperature and pressure can be selected according to the characteristics of the test film or sheet and the actual use conditions of the material.

4.2 Test equipment

4.2.1 Glass sheet

100mmx76mm, thickness is about 2mm.

4.2.2 Filter paper strips

150mmx76mm.

4.2.3 Oven

The control temperature is (50+/-2) degrees C. At the same time, ensure that after multiple samples are put in, there is at least a 50mm interval between each other, and the side wall of the oven

Above 50mm.

4.2.4 Load

The mass is 5.4kg.

4.2.5 Metal bars

The cross section is rectangular, the lengthxwidth is 76mmx15mm, and the weight is 50g and 100g each.

4.2.6 Metal clip

The length of the arm is about 100mm.

4.2.7 Double-sided tape

The width is about 12.5mm.

4.3 Test sample

4.3.1 Sampling size

The sample size is 150mmx76mm. The surface of the material with printed or decorative patterns is the test surface, and the reverse is the back. Wakasai

The material has no printing or decorative patterns, and either side is the test surface and is marked during the test.

4.3.2 Sample preparation

Take six samples. If the sample contains a variety of printed patterns and patterns, the sample is cut to include all the features of the pattern and pattern. Coil samples

The sample is cut more than 100mm from the edge, and more than 1m from the start and end. Test at least 16h after sample production.

4.4 Test procedure

4.4.1 The samples, glass slides and filter paper strips shall be adjusted for 24 hours in accordance with ISO 291.

4.4.2 Place the sample, filter paper and glass slide in the following order. glass slide/filter paper/sample with test side up/sample with test side down/

Filter paper/glass slide.

Align the above-mentioned sample combination all along its 76mm edge (see Figure 1).

A total of three sets of samples are prepared, excluding the case where the back side and the front and back of the two samples are bonded.

4.4.3 Put the sample combination into the oven and load a load of 5.4kg to ensure that the sample is subjected to a uniform pressure of 7kPa. At (50+/-2) degrees C

Keep it for 24h. After the end, unload the load, take the sample combination out of the oven and place it in a standard atmospheric environment for more than 2h, but not exceeding

After 24h.

4.4.4 Take out each pair of samples from the sample combination and place them flat on a horizontal table.

Use double-sided tape to glue a 50g or 100g metal strip to the free end of the lower sample (see Figure 2). And use double-sided on the other end of the lower sample

Glue on the horizontal surface.

Without printing surface, use 50g metal strip.

It has a printing surface and uses 100g metal strips.

There is a printed sheet in the depression or interlayer, which is treated the same as a non-printed surface.

Clamp the free end of the specimen with a metal clamp, and ensure that it clamps the entire width of the specimen. Lift by hand at a uniform speed of (25+/-2.5) mm/s

Lift the metal clip until the sample is completely separated. Record whether the metal strip is lifted from the horizontal surface.

Observe whether there are obvious visible cracks on the surface of the sample.

4.4.5 If the metal strip is lifted from the horizontal surface or the surface of the sample is damaged during the separation of the sample, it means that the material is stuck.

4.5 Test report

The test report includes.

a) This standard number and method A;

b) Complete and necessary valid information to identify the sample material;

c) Information on the metal strip material used;

d) Whether there is adhesion and damage, record it;

e) Test date.

5.1 Principle

After the sample combination is kept at a certain temperature and pressure for a certain period of time, the sample is fixed between the two clamps of the tensile testing machine to determine

And record the load required to separate it.

5.2 Test equipment

5.2.1 Constant speed tensile testing machine

The upper and lower aluminum fixture specifications are 100mmx100mm.

5.2.2 Glass sheet

100mmx76mm, thickness is about 2mm.

5.2.3 Filter paper strips

100mmx76mm.

5.2.4 Load

The mass is 2.3kg.

5.2.5 Oven

The temperature can be maintained at (50+/-2) degrees C.

5.2.6 Double-sided tape

5.3 Test sample

5.3.1 Sampling size

The sample size is 150mmx76mm. The long side of the sample is parallel to the side of the tester fixture.

5.3.2 Sample preparation

Cut ten samples at different positions in the width direction of the sample. The coil sample is cut more than 100mm from the edge, and the distance between the starting end and the

1m above the end. Test at least 16h after sample production.

5.4 Test procedure

5.4.1 The samples, glass slides and filter paper strips shall be adjusted for 24 hours in accordance with ISO 291.

5.4.2 Prepare 5 groups of test combinations, each group contains the same two samples as described in Method A, two filter paper strips and two glass slides. but

The edges of each layer are placed as shown in Figure 3.The orientation of the sample surface can be determined by the user (for example, judged by the test results of Method A). But should

Ensure that the directions of the five sets of samples are consistent. Combine the sample in a (50+/-2) degrees C oven and load 2.3kg (equivalent to 3kPa) and keep it for 3h.

After the end, unload the load and take out the sample assembly. Take out each pair of samples from the sample combination and place them in a standard atmospheric environment for more than 2 hours, but not

More than 24h.

5.4.3 Use a blade or spatula to place a pair of specimens on the lower clamp of the tensile testing machine, keeping the specimen in the center of the clamp (see Figure 4).

5.4.4 Raise the lower clamp until the upper clamp is close to directly above the specimen and the lower clamp.

5.4.5 Separate the edges of the specimen with a knife edge and fold them in the direction of the nearest fixture.

5.4.6 Use double-sided tape to fix the upper sample on the upper fixture, and the lower sample on the lower fixture (see Figure 5).

5.4.7 Adjust the paper speed of the tensile tester's recorder to 50mm/min, and the beam speed to 5mm/min.

5.4.8 Turn on the tensile testing machine and record the separation load during the whole process.

5.4.9 Repeat the above operation for the remaining 4 sets of sample combinations.

5.4.10 Record the maximum value of each group of sample combinations and calculate the average of the five groups.

Note. This method can be used to measure the force required to separate the adhered sample. However, the conditions under which adhesion occurs are unknown and may be different from those specified in this method.

Conditions, it is unreasonable to directly compare the results obtained with the above methods.