Moistureproof packaging, is to have ability to isolate water vapor through the use of packaging materials, cut packaging container goods and external environment, and other technical measures, stability of water content in items, by environmental humidity or water intrusion prevention packaging container, or prevent the outside packing container water escape and affect the quality of packaging container goods packaging technique.Now moisture-proof packaging has a very wide range of applications in medicine, cosmetics, most processed foods, chemical products, the respect such as weapons and equipment have a major role.
Containing water molecules in the air is known to all, and some of the products in the role of water molecules next time changes, which affect the quality and life of the product.Moisture can cause changes in the form of the following products:
(1) A physical change such as bread water loss after a hard, cookies after absorbing water is not brittle, dry leather hard backwardness and so on.
(2) The physical and chemical changes, such as sugar or salt caking, or formation water table, etc
(3) Chemical changes: the dirt on the surface of the bare metal that has been accompanied by moisture on adsorption, contamination have the effect of electrolyte, causes the electrochemical reaction, steel rust, or other metal corrosion, lose luster, Browning of food, etc.
(4) Biological changes: if the humidity increases more than the critical value or within the packaging in the formation of water droplets, mold or bacteria to grow.Humidity is one of the main bacteria and mold growth condition, reduce the humidity is the main means to control its growth.
Will need to be moistureproof packaging products are generally divided into the following three:
(1) After the moisture absorption of this kind of product will decline the quality goods water content increased to a certain extent, product use value will be lost. This type of product should be moistureproof packaging, prevent the product absorb water vapor.Such as crispy food, medicine, dried food, chemical products, fertilizer, etc.
(2) To take off the wet after this kind of product will decline the quality goods water loss to a certain extent, will lose their use value, with 3.1 class products, this kind of product to prevent to take off the wet packing, but also calls the moisture-proof packaging used.Such as bread, cake, Chinese traditional medicine pills, cosmetics and other products, such as water dispersible liquid products.For the above two kinds of products, they absorb moisture in the air, or to evaporate moisture in the air speed increased over time will gradually slow down, and finally reach the state of the water balance with the environment.Is if the constant temperature and humidity, the product of the equilibrium moisture content is constant, the water contained products then referred to as the balance of water temperature products.Under a certain temperature, air humidity is higher, the product is, the more the balance of water, and vice versa.
(3) Will react with water in the wet environment product this kind of product is not wet, moisture absorption and all but will react with water to make the product quality to drop, even lost use value.For example, metal products, weapons and equipment, precision instruments, etc in damp environment, if aerobic existence will rust steel components or make other metal surface lose luster.The humidity effects on corrosion;When the relative humidity is low. With the increase of humidity, corrosion rate increase is not too fast, but when the relative humidity after reaching critical humidity, metal corrosion rate has increased dramatically.
Therefore, we design in moisture-proof packaging, need according to the current environment humidity conditions and characteristics of the product itself, select the appropriate packaging materials and the reasonable structure of moisture-proof packaging, additions or taken to achieve the goal of moisture-proof packaging.