The main application scope of self sealing bag is in the field of food, which is used in the range of food that needs vacuum preservation. It is used to extract air from plastic bags, and then add nitrogen or other gases that are not harmful to food.

自封袋的主要作用：

The main functions of self sealing bag are as follows

1、在真空環境中阻止微生物的生長環境，避免周圍環境的污染，減少食品多位肉類食品中脂肪的氧化速度，對存在的酶類微生物生長環境進行抑制作用。

1. In the vacuum environment to prevent the growth of microorganisms in the environment, to avoid the pollution of the surrounding environment, reduce the oxidation rate of fat in food and meat, and inhibit the growth of enzymes in the environment.

2、自封袋可起到不使食品自身的水分蒸發，減少失水，保持產品質量。

2. The self sealing bag can prevent the food from evaporating, reduce the water loss and maintain the product quality.

3、自封袋自身袋體美觀性，易使人產生對產品的直觀感受，增加購買欲望。

3. The beauty of the self sealing bag can easily make people have an intuitive feeling of the product and increase their desire to buy.

自封袋選用防氧化即防止氧氣透過性及收縮性良好的聚偏二氯化乙烯，聚酯，聚酰胺材質；也有部分會用到尼龍、聚酯薄膜和聚乙烯多層材質進行復合。

The self sealing bags are made of polyvinylidene chloride, polyester and polyamide with good oxidation resistance, i.e. oxygen permeability and shrinkage resistance; some of them are made of nylon, polyester film and polyethylene multi-layer materials.

前面說的聚偏二氯化乙烯材質是阻氧阻水蒸氣效果好的薄膜類別，但自身確不耐熱封。聚酯具有很大的張力強度。尼龍的阻氧性能為良，耐熱性尚佳，但水蒸氣透過率過大，制造成本大。所以綜合來講，多數廠家會選擇復合材質來選取各種薄膜的優缺點。

The polyvinylidene chloride material mentioned above is a kind of film with good effect of blocking oxygen and water vapor, but it is not heat-resistant. Polyester has great tensile strength. Nylon has good oxygen resistance and good heat resistance, but its water vapor permeability is too high and its manufacturing cost is high. So generally speaking, most manufacturers will choose composite materials to select the advantages and disadvantages of various films.