The Relationship between Hot Tack Force of Packaging Material and Filling Efficiency
Abstract
This paper introduces the difference and relationship between the hot tack and ultimate strength. It uses example to introduce the close relationship between hot tack and choices of filling product line.
The heat seal property is the main index to evaluate the performance of the packaging materials. The heat seal property includes hot tack force and heat seal strength. Hot tack force refers to the peel force of the sealing area when it is not completed cooled down. Heat seal strength refers to the peel force when the sealing area is completely cooled down. Hot tack force and heat seal strength of the same material are usually quite different from each other. Actually the 2 indexes are directly related to the selection of packaging materials and the filling efficiency. This article is to introduce the application of hot tack force of the packaging material in filling production line.
1 The Application of Hot Tack Force
Today, Form-Fill-Seal machine has been widely applied in food, pharmaceutical, cosmetics and other fields. In the filling production line, flexible package making and product filling are carried out in the meanwhile. The filling method is basically to fill the product into the package from a certain height which would cause strong impact to the bottom of the package. If the bottom of package can not withstand the impact, it would break so there is a package breakage. Package breakage will contaminate the environment as well the filling efficiency would be influenced. In actual production, the interval between the heat seal process and product filling is quite short, so it is impossible for the sealing area cools down completely. Therefore heat seal strength is not suitable for evaluation of the heat seal property of the materials in production line. Through hot tack test, the operator could decide the optimum heat seal parameters for the packaging materials which has been considered as an effective way to shorten the packaging cycling process. To be concluded, a proper hot tack force of the packaging material could guarantee the normal running of the filling production line. Hot tack force would directly influence the filling efficiency and the package breakage rate. Heat seal strength is significant to the evaluation of the performance of the packaging material in storage in order to avoid the leak problems which may occur in transportation, storage and exhibition.Â
2 Case Study
How to obtain the optimum heat seal parameters in production line by testing the hot tack force of packaging material?
The following tests are performed to select proper packaging film from Film A and Film B (the other specifications are similar) which could meet the requirements for bag making and filling efficiency of the production line. Heat seal pressure, dwell time and sealing area are fixed in the production line. The heat seal temperature should not exceed 133°C and the hot tack force should be higher than 2N. Under the above conditions, the dwell time should be reduced as much as possible. As well energy consumption should be taken into consideration.
Apparatus: i-THERMOTEK 2500 Hot Tack Tester
Specimen: Film A and Film B
Dwell Time: 0.3s, 0.5s, 0.7s
Sealing temperature: 115°C, 118°C, 121°C, 124°C, 127°C, 130°C, 133°C
Other parameters were set in accordance with customer's requirements. The width of the test sample was 25mm specified by customer. The test curves which show the relationship between hot tack force, sealing temperature and dwell time for Film A and Film B are displayed in Figure 1 and Figure 2.
It could be seen from the test curve, there is an optimum sealing temperature at which the hot tack force is highest. When the temperature exceeds the optimum value, the hot tack force begins to decrease. As is shown in Figure 1 and Figure 2, the optimum sealing temperature for Film A and Film B is 130°C and 127°C respectively. Based on data for film A, when the dwell time is 0.3s, the hot tack force is lower than 2N which does not meet the customer's requirement. When the dwell time is 0.5s, sealing temperature at 127°C ~ 133°C, the material could just reach the value required by the customer. While when the dwell time is 0.7s and the temperature is between 127°C ~ 133°C, the hot tack force of the material could well satisfy the requirement of customer. Thus in the case of Film A, dwell time of more than 0.5s and temperature of 127°C ~ 133°C can satisfy the customer's requirements. For Film B, when dwell is no less than 0.3s and the temperature is in the range 118°C~133°C, it can satisfy customer's need for hot tack force. With the dwell time is increased, the sealing temperature could be decreased greatly. When the dwell time reaches 0.7s, the sealing temperature in the range of 115°C~133°C could meet the customer's requirement.
Based on the above analysis on test data, it is recommended to apply Film B in production line and the dwell time could be set within the range of 0.3s-0.5s and the sealing temperature could be 118°C. Of course, sealing temperature should also be further tested to determine the optimum value. It should be noticed that the factors of mechanical problem and the material should be taken into consideration when deciding the heat seal parameters. As far as the material is concerned, Film A is not suitable for production line which may decrease the filling efficiency and increase the energy consumption.
3 Conclusion
In order to obtain the optimum heat seal parameters for filling production line, hot tack force should be the major factor which should be taken into consideration. With hot tack tester, the dwell time for heat sealing and hot tack, sealing temperature and heat seal pressure could be adjusted as required. Based on the test data and test curves obtained in the test, and associated with the actual conditions of production line, the optimum heat seal parameters could be obtained so that the production cost could be reduced and the production efficiency could be improved.
Detailed information, pls contact Emily Wu at sales@labthinkinternational.com or visit our website: http://www.labthinkinternational.com/
