Introduction of PP polypropylene film for lithium battery tape substrate
Substrate: PP polypropylene filmPolypropylene is light in weight, with a density of 0.90～0.91g/cm³, which is the lightest kind of general plastics. Polypropylene has excellent heat resistance. The long-term use temperature can reach 100ºC～120ºC, and the use temperature can reach 150ºC without load. Polypropylene is the only general-purpose plastic that can be boiled in water and can withstand a disinfection temperature of 135ºC. The low temperature resistance of polypropylene is not as good as polyethylene, and the catalytic temperature is -10ºC～-13ºC (polyethylene is -60ºC). Poor impact resistance at low temperature or even room temperature, and easy brittleness at low temperature is the main disadvantage of polypropylene. Polypropylene is a non-polar material with excellent chemical stability, and the higher the crystallinity, the better the chemical stability. Except for the corrosive effects of strengthening acids (such as fuming sulfuric acid and nitric acid), there is no solvent that can dissolve polypropylene at room temperature. It is only low molecular weight aliphatic hydrocarbons, aromatic hydrocarbons and Chlorinated hydrocarbon has a softening or swelling effect on it. Its water absorption is very small, the water absorption rate is less than 0.01%. Polypropylene is susceptible to aging due to light, heat, and oxygen during molding and use. Polypropylene ages and becomes brittle after 12 days in the atmosphere, and deteriorates after being placed indoors for 4 months. The mechanical strength, rigidity and stress cracking resistance of polypropylene exceed that of high-density polyethylene, and it has outstanding elongation and bending fatigue resistance. , The living hinge made of it has undergone 7000 ten thousand bending tests, and there is no trace of damage. Polypropylene has excellent electrical insulation properties, especially high-frequency insulation, high breakdown voltage strength, and low water absorption. It can be used as a heat-resistant insulation material for batteries used at 120ºC. Its production is to first make a sheet or thick film from the melt of polymer polypropylene through a long and narrow head, and then in a special stretching machine, at a certain temperature and a set speed, at the same time Or it can be stretched step by step in two vertical directions (longitudinal and transverse), and made by appropriate cooling or heat treatment or special processing (such as corona, coating, etc.). With special acrylate glue that is resistant to electrolyte, it can produce termination tapes with a temperature resistance of over 80 degrees. TB1332 and TB1335 belong to this category. They can be used in the termination part of lithium battery cells. Digital termination tape TB1338 also belongs to this category. The advantages of this tape are softer, not easy to warp when bent, and bubbles are easily discharged during use. Disadvantages The pulling strength is not large. The base material has general temperature resistance and should not be used as a high-temperature tape, so it is generally not used as a tab tape and PACK tape.