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Source: Link Testing Instruments Co.,Ltd.

Why must the heat-sealing strength of pharmaceutical solid hard sheets be tested?

 

As the core substrate of aluminum-plastic blister packaging, the heat-sealing strength of pharmaceutical solid hard sheets with aluminum foil directly determines the sealing and barrier properties of pharmaceutical packaging. According to the "National Pharmaceutical Packaging Material Standard" (YBB00122002), heat-sealing strength is a key test item for pharmaceutical solid hard sheets. If the heat-sealing strength is insufficient, it may cause stratification and air leakage during transportation or storage, causing the drug to be damp, oxidized or even microbially contaminated, directly affecting the safety of medication.

 

Technical requirements for heat-sealing strength in the YBB standard

 

YBB00122002 clearly requires that the heat-sealing strength of pharmaceutical solid hard sheets and aluminum foil must be ≥6.0N/15mm. The formulation of this standard is based on the following core considerations:

 

1. Sealing reliability verification: Pharmaceutical packaging must withstand temperature fluctuations from -40℃ to 60℃, and the heat-sealing interface must maintain a stable bonding force to prevent sealing failure due to thermal expansion and contraction.

 

2. Barrier performance guarantee: oxygen permeability must be ≤0.5cm³/(m²·24h·0.1MPa), water vapor permeability must be ≤0.1g/(m²·24h), and sufficient heat seal strength is the basis for maintaining high barrier properties.

 

Heat seal strength test method and operating specifications

 

According to the YBB standard, the test must follow the following technical process:

 

1. Sample preparation

 

The solid hard sheet and aluminum foil were made into a composite sheet through a heat sealer (temperature 150±5℃, pressure 0.3MPa, time 1.5s), and cut into samples with a width of 15mm and a length of 200mm, with the heat sealing area centered.

 

2. Equipment parameter setting

 

Use an electronic tensile testing machine, set the clamp spacing to 100mm, and the tensile speed to 300mm/min to ensure that the test conditions meet the GB/T 8808-1988 standard.

Heat Seal Tester LTH-H3

 

3. Test process

 

Clamp the two ends of the sample in the upper and lower clamps respectively, make the heat seal line perpendicular to the center line of the clamp, stretch at a constant speed until it is completely peeled off, and record the maximum peeling force value.

Automatic Tensile Tester XLW-500N

 

4. Result determination

 

Heat seal strength = maximum peeling force (N) / sample width (mm), the calculation result must be accurate to 0.1N/15mm. If the three sets of parallel tests are all ≥6.0N/15mm, it is determined to be qualified.

 

Conclusion

 

Heat seal strength detection is a core link of quality control required by the YBB standard, which is directly related to the long-term stability of drug packaging. Through standardized testing and data traceability, companies can quickly locate process defects and optimize heat sealing parameter combinations.

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