There are generally two kinds of combined sealing methods for bottle cap and bottle. One is the pressure sealing type with elastic materials lined between them. Depending on the elasticity of the elastic materials and the additional extrusion force driven during tightening, a relatively perfect seamless seal can be achieved, with a sealing rate of 99.99%. The structural principle is to pad a special annular elastomer material at the joint between the bottle port and the inner bottom of the bottle cap. At present, it is widely used on packages with internal pressure, and only those with internal pressure need this form, such as Coca Cola, Sprite and other carbonated soda.
Another form of sealing is plug sealing. Plugging is to seal by plugging it. According to this principle, the designer designed the bottle cap as a stopper. Add an additional ring to the inner bottom of the bottle cap. The bulge in the first third of the ring becomes larger, forming an interference fit with the inner wall of the bottle mouth, thus forming the effect of the stopper. The corked cap is allowed to be sealed without tightening force, and the sealing rate is 99.5%. Compared with the former method, the bottle cap is much simpler and more practical, and its popularity is quite high.