1. Test significance

With the survival of the fittest in drug packaging forms, blister packaging has become an important component of the 

current drug packaging market due to its advantages of good protection, convenient use, and lightweight quality. 

Bubble wrap packaging, also known as blister packaging or PTP packaging, mainly consists of two parts: plastic hard 

sheets with blister holes and medicinal aluminum foil. When packaging, the drug is placed in the blister cells of the hard 

sheet and then heat sealed with medicinal aluminum foil, forming independent blister packs for each blister cell. Due

 to the fact that the destruction of one blister in the blister pack does not have a significant impact on the integrity of

the other blister packs, the sealing integrity of each blister pack itself is particularly important. If the sealing of the blister

 packaging is poor, gases such as water vapor and oxygen in the external environment will penetrate into the interior of

 the packaging along the poorly sealed area, causing deliquescence, discoloration, and other phenomena of the drug.

2. Standard

At present, the sealing performance test mainly refers to GB/T 15171-1994 "Test Method for Sealing Performance of 

Flexible Packaging Components", which is applicable to the sealing performance test of sealed flexible packaging

 components made of various materials.

3. Test sample

A certain brand of granular medicine is packaged with blister packs.

4. Experimental equipment

This article uses the Paratronix LT-02P sealing tester to test the sealing performance of blister packaging samples.

4.1 Experimental principle

This device is developed based on the principle of differential pressure testing. During the experiment, the sample is 

placed in water in a sealed container, and a vacuum is applied to the inside of the sealed container to create a pressure

 difference between the inside and outside of the sample immersed in water. If the sealing performance of the sample

is poor, under the action of the pressure difference, the gas inside the sample will overflow to the outside along the weak 

sealing area on the surface of the sample, manifested as continuous bubbles on the surface of the sample in water, or by 

observing the shape recovery of the sample after expansion and release of vacuum, the sealing performance of the 

sample can be judged.

4.2 Scope of Application

This equipment is suitable for testing the sealing performance of packaging bags, bottles, tubes, cans, boxes, etc. in

 industries such as food, pharmaceuticals, medical equipment, daily chemical products, automobiles, electronic 

components, stationery, etc., including glass, plastic, metal materials, etc. Suitable for testing the sealing performance 

of specimens after drop, pressure resistance, and other tests.

This equipment complies with multiple national and international standards, such as GB/T 15171, ASTM D3078, etc.

5. Experimental steps

(1) Soak the blister pack sample in water in a sealed jar.

(2) Close the sealing cover to ensure that there is no air leakage around the sealing cover and that the sealing tank is well 

sealed. Set the test parameters such as the required vacuum degree and the holding time inside the vacuum tank through 

the microcomputer operation interface.

(3) Turn on the vacuum pump, click the test button on the operation panel, and the test will begin.

(4) Observe the bubbles on the surface of the sample during the vacuum pumping and pressure holding process. If there 

are continuous bubbles on the surface of the sample, record the pressure value and location of the bubbles when they 

appear. If there are no continuous bubbles, it indicates that the sample has good sealing performance under the set pressure.

6. Experimental results

In this experiment, a total of 5 bubble wrap samples were tested, and all 5 samples showed air leakage. Among them, 4

 samples showed air leakage at the heat sealed edge, with pressures of -31.5 KPa, -70.0 KPa, -26.9 KPa, and -43.1 KPa at 

the time of air leakage. The other sample still did not leak at the maximum negative pressure of the instrument -90 KPa, 

demonstrating good sealing performance.

7. Conclusion

Sealing performance is an important performance of bubble wrap packaging. The LT-02P sealing tester is a professional 

testing equipment used to test the sealing performance of bubble wrap packaging. It can quantitatively analyze the sealing

 performance of the packaging and provide a basis for improving the packaging process by qualitatively analyzing the location 

of air leakage.