Pharmaceutical aluminum foil and PVC heat seal strength test

In this test, at the speed specified by the tensile machine, vertical uniform tensile force is applied to the adhesive surface of the sample, and the sample is peeled at an angle of 180° to measure the average strength required for peeling the aluminum foil and the PVC hard chip. Test equipment: automatic recording tensile tester, lever-type heat sealer, and standard test piece cutter.
1. Sample Preparation Requirements: 1 Sampling: Cut 100mm×100mm test pieces in finished aluminum foil, meet the requirements of GB5663 for medical use PVC hard sheets 100mm×100mm test pieces; 2 Heat sealing conditions: Lever type heat sealing The temperature of the instrument is 150-160°C, the pressure is 0.2×104Pa, and the time is 1s. 3 Operation: The adhesive layer of the sample is laminated with the PVC sheet, inserted into a heat sealer for heat sealing, and cut into 15mm width with a standard cutter. For the sample, take the middle three for testing.
2. Test methods and procedures: 1 Adjust the tensile tester and make the recorder pointer “zero”. "Zero" adjustment: When the test pointer is in the "zero" position, the pendulum should be vertical. Increase or decrease the weight on the fact that the "zero" remains unchanged. If you find that the "zero point" is inaccurate, identify the reasons for adjustment in time. The general “zero point” should not have the following phenomena: a. The heavier the twist, the greater the value of the pointer. The most obvious is between the empty swing bar and the maximum squat. Cause: The position of the balance pole is incorrect, causing the swing bar not to be vertical. Adjustment method: adjust the balance 铊 to increase the maximum 铊 and no increase 铊 indicate the same value. b. The heavier the crown is, the smaller the indicator value is, and the most obvious is between the empty swing bar and the largest pole. Cause: The position of the balance pole is incorrect, causing the swing bar not to be vertical. Adjustment method: Adjust the balance in the opposite direction from the previous item, until the maximum value is the same as the value without the indicator. c. Regardless of which one is added, the pointer will not indicate zero, but the position will not change. Cause: The initial position of the indication gear is incorrect. Adjustment method: Adjust the ball until the pointer points to zero. 2 set the tensile speed is 200mm/min, the PVC in the sample is clamped on the upper clamp of the tester, the aluminum foil in the sample is clamped on the lower clamp of the tester, the standard peeling angle is 180°, and the sample is peeled off, the test The automatic recording device records the peeling load and the peeling length, and draws the peeling load curve.
3. Test results: 1 The average value of the curve drawn by the automatic recorder is the heat seal strength value (unit: N/15mm width); 2 The heat seal strength can be expressed by the formula: Q=k·L/b Medium: K-peel curve on the load unit represented by the load coordinate unit length N
Length of the load coordinate in the effective peel length on the L-peel curve mm
B—the width of the sample bonding layer mm
When L is calculated by a planimeter method, it should be accurate to 0.1 cm. If the peeling strength fluctuates beyond 15% of the average peel strength in the effective peel length, the test data of the sample is invalidated. Calculate the average value of each group of samples should take two significant figures, and apply the formula to calculate the standard deviation.
Third, the pharmaceutical aluminum foil and PVC heat seal strength test factors:
1. Bonding area: The heat-sealing strength of aluminum foil and PVC are expressed by the force per unit area. In the test, the size of the bonding area has influence on the bonding strength; the bonding area is too small, and the preparation of the sample is not easy. Accuracy, the relative error of the bonding measurement is also larger, the increase in the bonding area, the probability of bonding defects increases, so the determination of the heat sealing strength should be prepared according to the required width of the length of the sample.
2. The clamping method of the sample: At present, the adhesion performance of PVC and aluminum foil is generally determined by a pendulum pulling machine. According to the force measuring principle of the pendulum pulling machine, the force measured by the testing machine can be introduced as the force in the direction of the lead weight of the sample. If the direction of the force received by the sample deviates from the vertical direction, the measured force is The component force in the vertical direction is therefore smaller than the actual force applied to the sample. In other words, if the line of action of the force exerted by the specimen deviates from the vertical line passing through the center of the fixture, the test result will be low. Therefore, the center line of the fixture, the line of action of the force applied to the specimen, and the vertical The three lines coincide.
3. The tensile speed of the testing machine: the tensile speed of the testing machine is different from the selected value. The test results are different. With the increase of the tensile speed, the heat seal strength value increases. Therefore, the tensile speed of the tensile force must be specified as 200mm/min.