Speaking of the choice of diapers, every mother may have different requirements, but there is always one thing that is indispensable, that is, ventilation. Every layer of a good diaper has a "breathable" design, and the material should also have related functions, including breathable film.

1.What is breathable film

In fact, breathable film is no stranger to us. It generally refers to PE functional materials with environmental protection, water isolation and air permeability. It is mainly used for female sanitary napkin bottom film, pad bottom film, baby diaper bottom film, etc. When compounded with non-woven fabrics, it is also widely used in medical protective clothing, isolation clothing, medical mattresses, disposable bedding, home textile products, etc. Apart from its own material function, the process is also very important for whether the diaper film is breathable.

2.Principle of breathable film

In short, the principle of breathable film is: inorganic material + stretching = micropore. Although it seems very simple, the actual operation is also very particular. It is effective only when the size is appropriate and the micropore distribution is uniform. If it is not stretched enough, the pore diameter is too small or even has no pore diameter, or it is poorly stretched and the pore size is insufficient, it can only become a waste product.

When the water vapor concentration on one side of the membrane is greater than the environment on the other side of the membrane, a humidity gradient pressure difference is formed. This provides the basic conditions for gas (steam) convection. Due to the formation of convection, the humidity environment on both sides of the film tends to be relatively balanced, which is its basic principle.

3.Waterproof function of breathable film

In addition to air permeability, it also plays a very important role, that is, as a water barrier membrane, it can block liquids. There are many channels in the film, which make the "l/d" value of the zigzag channel formed by it very large, which can be understood as a capillary. Therefore, under the same liquid (such as water) and the same pressure, as long as the liquid column height of the capillary is less than the length of the capillary, it can ensure that the liquid will not leak.

Therefore, the water barrier performance of the membrane directly depends on its pore size and path length. This performance is usually achieved by resistance to water pressure（ΔP) To measure. When the water pressure exceeds the water pressure resistance that the microporous membrane can bear, the water will leak. Therefore, when the diaper reaches a certain bearing capacity, it should be replaced in time to avoid the occurrence of liquid leakage.

4.Common adhesive for breathable film

The breathability of breathable film mainly depends on the number of air holes in the breathable bottom film and the manufacturing process, but it is difficult to see with the naked eye during the purchase process, so we will pay attention to the smell. When it comes to smell, we inevitably think of colloids. For example, hot melt adhesive commonly used for high-quality diapers. Hot melt adhesive is a kind of plastic adhesive. It is solid at room temperature. After heating and melting, it can be quickly bonded, and can be repeatedly heated and bonded many times. Although the physical state of hot melt adhesive changes with the change of temperature within a certain temperature range, its chemical properties remain unchanged. Moreover, it is non-toxic and tasteless, and belongs to an environmental friendly chemical product. It has stable performance and is very convenient for storage and transportation.

However, the urine glue and structural glue, which are very common in the market, are relatively low in price and harmless to human body. Some enterprises will use them for products with relatively low prices to reduce costs, but the disadvantage is that they have a large smell, poor viscosity and are easy to degumm. Therefore, if you sometimes smell the smell of diapers, it may be the smell of breathable film. However, the taste of diapers is determined by many factors. The taste of most good raw materials can be reduced or even eliminated through ventilation, so there is no need to worry too much.

Finally, when choosing diapers, it is best to choose large manufacturers of regular brands. In this way, first of all, the materials are guaranteed and the technology is relatively advanced. Take diaper film for example. In order to protect the baby's hips more effectively, it must be breathable, waterproof and not too hard. Therefore, it is also important to choose the right brand.