PE film is not just a kind of film, it can also be subdivided into high-pressure material and low-pressure material, in fact, if you are careful, you can tell the difference between the two just from the appearance of touch: PE film is tough, and the material is smooth, the hand will feel as comfortable as silk; low-pressure material is widely used because of its low cost, this material is slightly rough, but it is good in hardness and can The reason why the low-pressure material is widely used is its low cost, this material is slightly rough, but better than the hardness, to withstand the heavier goods, like plastic undershirt bags are made of low-pressure material. In fact, there is a more simple method, that is, by tearing the plastic bag after observing whether the white marks to identify the white marks is low pressure, and vice versa is high pressure. This method is based on the high density of high-pressure material, it is not easy to produce white marks. PP film is slightly worse than PE film in terms of performance, its burst mouth has been a problem for people to worry about, because of its high transparency, resulting in the attenuation of tensile strength, for this reason it is often used to hold gifts, although not practical, but because of the transparency of the problem also step into one of the necessary products of high-end goods. When identifying PP film, it is often observed by folding it, because its material is relatively hard, as long as a fold, it is easy to appear creases, which do not appear in PE film.