Why only stainless steel water cups can be used as thermos?And water cups made of other materials can't be thermos cups?

About this topic, more than one friend has asked the editor, and more than 100 friends have asked the editor.Today I will tell you why.However, strictly speaking, the title is not rigorous enough, but in order to let everyone understand the editor at once, I set the title like this first.

What is a thermos cup? Are there any strict requirements for thermos cups in the world?

As the name suggests, a thermos is a water cup that preserves temperature.This temperature represents both heat and cold, which means that the hot water in the water cup can be kept hot for a long time, and the cold water in the water cup can be kept cold for a long time.Internationally, there are definitions and regulations for thermos cups.

Pour hot water at 96 degrees Celsius into the cup, seal the lid tightly, and open the lid after 6-8 hours to test that the water temperature is 55 degrees Celsius.Of course this rule was proposed many years ago.With the continuous improvement of production technology and craftsmanship, some thermos cups can even be kept warm for 48 hours through changes in product structure and craftsmanship.

How to make the water cup have good thermal insulation performance?

At present, global unification is still achieved by vacuuming.It is to extract the air in the interlayer of the original double-layer cup body, so that the interlayer can be imagined as a vacuum state, which acts as a physical phenomenon of rejecting heat conduction, so that the water temperature in the cup will not be lost so quickly.

Please note that the editor said that it will not drain so fast, because although the wall and bottom of the cup are double-vacuated, the mouth of the cup must be open.In addition, most of the cup lids are not metal vacuumed, and the heat will rise, so the temperature will be lost from the cup mouth.

The vacuuming process requires a vacuuming furnace to complete.The temperature in the furnace is as high as several hundred degrees Celsius, so obviously the double-layer water cup made of plastic material will melt and deform at such a temperature.Ceramics can withstand such temperatures, but because the interlayer pressure is higher than the ambient pressure after vacuuming, the ceramics will burst.There are also some materials such as silica gel, glass, melamine, wood (bamboo), aluminum and other materials that cannot be made into thermos for this reason.

Therefore, the qualified metal materials that meet the food-grade requirements and similar in strength to stainless steel can be made into thermos cups, and other materials cannot be made into thermos cups.