First, what is the effect of heat sealing temperature on heat sealing strength?
The heat sealing temperature has a very important influence on the heat sealing strength. The thickness of the film involved in the heat sealing layer plays a decisive role in the heat sealing effect.
(1) when the temperature is relatively low, the surface of the heat sealing layer is melted, and the thickness of the film involved in the heat sealing is relatively thin, resulting in a lower contact temperature.
(2) when the temperature is too high, the Heat seal film may be melted or the heat seal layer may be stripped of the base layer, resulting in the base layer of the upper and lower films participating in the heat seal, which will inevitably lead to a decrease in the heat seal strength.
Therefore, when we carry out film Heat sealing, we must choose the appropriate heat sealing temperature, not too high or too low. Second, what is the effect of heat sealing time on heat sealing?
The heat sealing time of automatic packaging machine or old bag making machine is determined by the machine speed.
Under the condition of constant heat sealing temperature and heat sealing pressure, the longer the Heat sealing time is, the stronger the combination between the Heat sealing layers is.
However, if the Heat sealing time is too long, the Heat sealing part of the composite film will be wrinkled and uneven, which will seriously affect the appearance quality of the product. Third, what is the effect of heat sealing pressure on heat sealing?
In order to ensure the heat sealing strength of plastic composite flexible packaging, a certain heat sealing pressure is essential.
Therefore, in the heat sealing process, the Heat sealing pressure is required to be moderate and uniform.
If the Heat sealing pressure is not enough or uneven, bubbles will appear in the heat sealing part and virtual welding will occur, resulting in poor heat sealing.
If the Heat sealing pressure is too large, the sealing deformation will occur at the Heat Sealing Part. When the heat sealing temperature is high, some composite materials will be squeezed out, causing the edge of the heat sealing to be brittle and easy to crack, at the same time, the Heat sealing strength is reduced.
Fourth, what are the reasons for the uneven heat sealing pressure? 1 Heat sealing knife deformation.
The heat sealing knife is generally made of aluminum or copper with good heat transfer performance. These two materials are relatively soft, so when installing the Heat sealing knife, if the method of tightening the fixing screw is wrong, it will cause the Heat sealing knife to be unevenly stressed, and after frequent tool change, the Heat sealing knife will be deformed. (2) the machining accuracy of heat sealing cutter is low.
Low machining accuracy of the heat sealing knife will cause uneven surface of the heat sealing knife, thus causing uneven heat sealing pressure in the heat sealing process, thus affecting the Heat sealing strength of the composite packaging bag. 3 The surface of the heat sealing knife is sticky or injured.
The surface of the heat sealing knife is stuck with stolen goods or the surface is bruised or scratched, which will also cause uneven heat sealing pressure. In addition, the melting resin is stuck on the surface of the heat sealing knife and is not cleaned in time, which will also affect the Heat sealing strength. 4 hardness and strength of silicone skin.
The quality of silicone skin is the most important condition to ensure uniform heat sealing pressure.