Plastic bag hot pressing technology is a process that uses heating and pressurization to melt and fuse the materials of plastic bags (thermoplastics such as polyethylene and polypropylene) at the contact parts, thereby achieving sealing or connection. The following is a detailed introduction to its technical principles, operation process, applications and precautions:
1. Technical principles:
Thermoplastics will soften and melt when heated to a certain temperature. At this time, pressure is applied to make two or more layers of plastic materials in close contact. After cooling, the melted part re-solidifies to achieve a firm connection. For example, the melting point of common polyethylene plastic bags is generally between 100℃-130℃. When heated to this temperature range, polyethylene will soften.
2. Operation process
Preparation: Check whether the hot pressing equipment is operating normally and set the appropriate temperature, pressure and time parameters. Plastic bags of different materials and thicknesses require different parameters. For example, for thinner polypropylene plastic bags, the hot pressing temperature may be 160℃-180℃, the pressure is about 0.2-0.3MPa, and the time is 1-2 seconds. Prepare the plastic bags to be hot pressed and ensure that their surfaces are clean, dry, free of debris and moisture.
Placing plastic bags: Place the plastic bags to be hot pressed on the workbench of the hot pressing equipment, align the parts to be hot pressed, and use clamps or positioning devices to fix the plastic bags to ensure the accurate hot pressing position.
Hot pressing operation: Start the hot pressing equipment so that the heating element applies heat and pressure to the plastic bag. During the hot pressing process, pay close attention to the changes in temperature, pressure and time to ensure that the hot pressing effect meets the requirements.
Cooling and shaping: After the hot pressing is completed, maintain the pressure for a period of time to allow the plastic bag to cool and shape naturally under pressure to enhance the connection strength of the hot pressing part. The cooling time depends on the thickness and material of the plastic bag, generally ranging from a few seconds to tens of seconds.
Take out the plastic bag: After cooling, loosen the clamp or positioning device, take out the hot pressed plastic bag, and check the quality of the hot pressing, such as whether there is leakage, cold welding and other problems.
3. Application:
In the production of plastic bags, it is used to make packaging bags of various specifications, such as food packaging bags, daily necessities packaging bags, industrial products packaging bags, etc.; in the packaging industry, it is used to seal plastic bags that have been filled with items to ensure the sealing and safety of the items, such as supermarket shopping bags, express packaging bags, etc.
4. Precautions:
Strictly follow the equipment operating procedures to avoid equipment damage or personal injury due to improper operation; regularly maintain and maintain the hot pressing equipment to ensure the stability and reliability of the equipment's performance; control the hot pressing temperature, pressure and time to avoid hot pressing quality problems due to improper parameters. If the temperature is too high, the plastic bag may be deformed and burned, and if the temperature is too low, the hot pressing may be unstable.
