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、在真空环境中阻止微生物的生长环境，避免周围环境的污染，减少食品多位肉类食品中脂肪的氧化速度，对存在的酶类微生物生长环境进行抑制作用。

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发，减少失水，保持产品质量。

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

3、自封袋自身袋体美观性，易使人产生对产品的直观感受，增加购买欲望。

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.

自封袋选用防氧化即防止氧气透过性及收缩性良好的聚偏二氯化乙烯，聚酯，聚酰胺材质；也有部分会用到尼龙、聚酯薄膜和聚乙烯多层材质进行复合。

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.

前面说的聚偏二氯化乙烯材质是阻氧阻水蒸气效果好的薄膜类别，但自身确不耐热封。聚酯具有很大的张力强度。尼龙的阻氧性能为良，耐热性尚佳，但水蒸气透过率过大，制造成本大。所以综合来讲，多数厂家会选择复合材质来选取各种薄膜的优缺点。

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.