Abstract: This paper introduces the difference and relationship between hot tack and heat seal strength in detail, and introduces the close relationship between hot tack and parameter selection of filling production line. Keywords: heat sealing performance, hot tack, filling, broken bag, efficiency The heat-sealing performance of packaging materials is the main indicator for evaluating the packaging performance of materials, including hot tack and heat-sealing strength. The peeling force of the heat-sealed portion of the material after a heat seal for a short period of time (not yet cooled) is the thermal viscosity of the material. Hot Tack, and the Ultimate Strength is the peel strength after the heat-sealed portion is completely cooled. The two indexes of the same material vary greatly. However, in fact, the good application of these two indicators is often directly related to the choice of packaging materials and the actual filling efficiency. This paper introduces the application of the hot tack of materials and the analysis and evaluation by taking the packaging material selection as an example. Pharmaceutical Intermediates,Organic Medical Pharmaceutical Intermediate,Cyanamide 50% Solution,Cyanamide 98% Solid Ningxia Darong Chemicals & Metallurgy Co., Ltd. , http://www.darong-cyanamide.com
Figure 1. Film A: Relationship between hot tack and heat seal temperature and heat seal time
Relationship between hot tack and packaging efficiency of packaging materials
1. Use of hot tack
Today, most of the soft packaging fillings in food, pharmaceuticals, cosmetics, and other fields use Form-Fill-Seal Machines. In these filling production lines, the manufacturing process and filling process of the flexible packaging bags are carried out simultaneously, and the way of filling the products is basically that the products fall into the packaging bags from a certain height and have a strong impact on the bottom of the packaging bags, if packaging The bottom of the bag can not withstand the impact of the impact will occur at the bottom of the crack - broken bag, not only will affect the cleaning of the production environment, but also affect the filling efficiency. Since the interval between the heat-sealing of the bag and the filling of the contents in the filling line is very short, it is impossible to completely cool the heat-sealed portion of the bag in such a short time interval, as can be seen from the packaging material. The heat seal strength is not suitable for the evaluation of the heat sealing properties of the material here, and the hot tack of the material should be used. Optimizing the heat sealing process during the packaging process has been widely recognized as an effective way to shorten the packaging cycle time, and hot tack testing can help operators select the optimal heat sealing parameters.
Therefore, the difference between the application of hot tack and heat seal strength is very clear. The hot tack property is used to ensure the normal operation of the filling line, and its suitability directly affects the filling efficiency and the bag breaking rate; It is mainly used to evaluate the storage performance of materials, to ensure that the heat-sealed parts will not leak during transportation, storage and display, and is a prerequisite for realizing the functionality of packaging materials.
2. Case analysis
How to choose the best line heat sealing parameters by testing the hot tack of the material? Let's take the customer test commission accepted by Labthink Lab as an example to introduce the relationship between hot tack and heat sealing parameter selection.
The customer is a food production enterprise in Southeast Asia. It is desirable to choose one of the two types of A and B films with similar performance indicators to meet the requirements of production line bag making, and to make the production line have higher filling efficiency. Affected by other factors, the hot tack time and heat seal pressure that the production line can provide have been determined, and the thermal cover of the material is also determined. The customer requires that the heat sealing temperature of the packaging material is not higher than 133 ° C, the hot tack is not less than 2 N, and the heat sealing time should be shortened as much as possible on the basis of meeting the above requirements, and the principle of energy saving should be taken into consideration.
We used the Labthink HTT-L1 hot-adhesive tensile tester to test the hot tack of A and B films. The heat seal time was set to 0.3s, 0.5s, 0.7s, and the heat seal temperature was set to 115°C and 118°C. 121 ° C, 124 ° C, 127 ° C, 130 ° C, 133 ° C, other indicators according to customer requirements, test sample width according to customer requirements for 25mm. Figures 1 and 2 are test data curves.
Figure 2. Film B: Relationship between hot tack and heat seal temperature and heat seal time
In fact, there is a most suitable temperature point to achieve the optimum thermal adhesion of the film material, and the hot tack will show a downward trend when the heat sealing temperature exceeds this temperature point. As can be seen from Figures 1 and 2, the optimum heat sealing temperature of film A is about 130 ° C, and the optimum heat sealing temperature of film B is about 127 ° C.
On the data analysis, for film A, when the heat sealing time is 0.3 s, the hot tack does not meet the customer's requirements; when the heat sealing time is 0.5 s, the heat sealing temperature is between 127 ° C and 133 ° C. The hot tack can just meet the customer's requirements; when the heat sealing time is 0.7s, the heat-sealing temperature of the material in the range of 127 ° C ~ 133 ° C can better meet the requirements. Therefore, for the film A, only when the heat sealing time is more than 0.5 s, and the heat sealing temperature is 127 ° C ~ 133 ° C can meet the customer's requirements for the hot tack of the material. The film B exhibits a much better thermal adhesion than the film A under the same heat sealing parameters. When the heat sealing time is not less than 0.3 s and the heat sealing temperature is between 118 ° C and 133 ° C, the customer can satisfy the heat. The requirements of the adhesive force; and as the heat sealing time increases, the required heat sealing temperature drops significantly. When the heat sealing time increases to 0.7 s and the heat sealing temperature is at any temperature point between 115 ° C and 133 ° C, the film B is Can meet the requirements of customers.
Referring to the above test data, we believe that film B should be used, and the heat sealing parameters of the production line can be set as follows: heat sealing time is 0.3 s ~ 0.5 s, heat sealing temperature is 118 ° C. Of course, the heat sealing temperature point should be further tested to determine the optimum value, but note that the hot tack should be left with a certain margin to avoid the lack of strength due to heat sealing mechanism factors or material factors. The problem. From material analysis, we believe that using A sample will reduce the filling efficiency and increase the energy consumption of the production line. However, further data analysis should also consider the cost of packaging materials and the best working efficiency of the entire production line.
3. Summary
In order to reasonably set the heat sealing process parameters of the filling production line, the hot tack of the material should be mainly considered. Using the hot-adhesive tensile tester, we can adjust the heat-sealing time, hot-stick time, heat-sealing temperature and heat-sealing pressure at will, and analyze the best parameter combination mode from the test data chart combined with the actual situation of the production line. Of course, material costs should also be taken into account in order to optimize production costs and production efficiency.