Heat Seal Strength Test Method

The heat seal strength test method is a commonly used quality inspection method to evaluate the performance and reliability of heat seal materials. This article will introduce the principles, procedures, and common testing instruments and techniques of heat seal strength testing. By reading these contents, you can understand the importance and application areas of heat seal strength testing.

Heat Seal Strength Test Method

The heat seal strength refers to the strength of the seal within the flexible barrier materials and can be used to determine consistency within the seal, as well as evaluation of the opening force of the package system. Usually, the heat seal strength depends on those heat seal parameters including sealing temperature, sealing pressure, and dwell time.

The determination of suitable sealing parameters is significant to the performance and quality of the package. To be specific, if the sealing parameters are too low, due to insufficient seal strength, the sealing layer may not be able to combine together tightly and as a result, the sealing edges may break or leak. On the other hand, if the sealing parameters are too high, the sealing area may shrink and as a result, the package may break from the root. Therefore, it is quite important for the manufacturers of flexible plastic medical packaging to control the seal strength by selecting suitable sealing parameters.

Testing Equipment

This article provides a simplified method for the determination of heat sealing parameters of flexible plastic medical packaging with Saicheng’s HST-H3 Heat Seal Tester and XLW-H Tensile Testing Machine.

Test Environment

The sample should be placed in an environment with a temperature of 23°C±2°C and a relative humidity of 50%±5% for more than 4 hours, and conduct the test under this condition.

The tests shall be performed according to the following procedures.

Specimen Preparation

Switch on HST-H3 Heat Seal Tester. Set sealing pressure, dwell time, and sealing temperature. The temperature of the lower sealing jaw can be set at one fixed temperature or the same as the room temperature, while the temperature of the upper sealing jaws can be set as required. When the preset sealing temperatures are reached, stack 2 pieces of specimens together (sealing surface to sealing surface). Then insert the specimens into between the upper and lower sealing jaws along the length direction to start heat sealing.

Testing Method

Take the sample, take the heat-sealed part as the center, open it to 180°, and clamp the two ends of the sample on the two clamps of the XLW-H Tensile Testing Machine, the axis of the sample should coincide with the center line of the upper and lower clamps, and require proper tightness to prevent The sample slipped or fractured in the fixture before the test. The distance between the clamps is 50mm, the test speed is 300±30mm/min, and the maximum load when the sample is separated or broken is read.

If the sample is broken in the fixture, the sample is invalid, and another sample is taken to redo.

Conclusion

Test results, the material is the arithmetic average of 5 samples in the longitudinal and transverse directions, and the composite bag uses the average of 10 samples in different heat-sealing positions as the heat-sealing strength of the sample, and the unit is expressed in N/15mm.