The main material of stand up pouch is generally PE polyethylene PP polypropylene, and food bags are widely used in food packaging.Synthetic resins are almost always used in food bags. Resin is the most important component in plastics, which acts as an adhesive and can bond other components of the plastic into a whole. According to the changes that occur when heated, synthetic resins can be divided into two types thermoplastic resins and thermosetting resins.
Thermoplastic resin has the properties of being softened by heat and hardened by cooling, and does not have a chemical reaction. This property can be maintained no matter how many times the heating and cooling are repeated. The molecular structure of all thermoplastic resins is linear. It includes all polymerized resins and partially condensed resins.
Thermoplastic resins include polyethylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, rubber and the like. The advantage of thermoplastic resin is that it is easy to process and shape and has high mechanical energy. The disadvantage is poor heat resistance and rigidity.Thermosetting resin The resin undergoes a chemical change after heating, and gradually hardens into shape.
It will not soften or dissolve when heated. The molecular structure of thermosetting resin is body type, which includes most of the condensation resin. The advantage of thermosetting resin is high heat resistance and not easy to deform under pressure. The disadvantage is poor mechanical properties. Thermosetting resins include phenolic, epoxy, amino, unsaturated polyester and silicone ether resins.