The outer shell of the battery is used to hold the electrolyte and the plate group. The outer shell should be acid-resistant, heat-resistant and shock-resistant. It was previously made of hard rubber. Now China has begun to produce polypropylene plastic shell. The shell is not only resistant to acid, heat and shock, but also has high strength. The shell wall is thin (usually 3.5mm, while the hard rubber shell wall thickness is 10mm), light weight, beautiful appearance, and transparency.
The battery case is used to hold the electrolyte and the plate assembly and should be made of a material that is resistant to acids, heat, vibration, and insulation, and that has a mechanical strength. Most of the early-generation starter batteries used hard rubber housings. In recent years, with the rapid development of engineering plastics, polypropylene plastic housings have been used. Compared with hard rubber shell, it has better toughness, thin wall and light wall thickness is only 3.5mm, and the thickness of plastic shell is about l0mm).
The production process is simple, the production efficiency is high, the heat sealing is easy, the harmful impurities are not brought in, the appearance is beautiful, the transparency is low, and the advantages are low. The
The hard rubber used in the earlier tanks, lids, and other parts was vulcanized rubber (sulphur content was 25% or more), and different types of fillers and accelerators were added. Natural rubber was used at that time, and it was gradually replaced by synthetic rubber after the 1960s. At present, except for the large-capacity starter battery, the battery tanks in other categories are made of plastic material.