1. The liner itself has very small gaps (holes or cracks);
Second, the small pointed under the gallbladder is damaged.
Third, the bottle cap is damaged, such as not sealed, etc.;
4. Intrusion of water between the inner liner and the outer casing;
5. The vacuum inside the sandwich is not balanced.
Generally, the tail of the bottom of the bottle is broken, or the outer bottle is cracked, which causes the vacuum layer to lose its heat insulation effect.
The bottle is vacuumed in double glazing to avoid heat transfer. After the bottle leaks, the inside is not a vacuum. The hot water in the thermos can dissipate the heat to the external space through heat conduction, so the thermos bottle is not insulated.