Author：Baby & Adult Diaper Materials FROM：Diaper Materials Manufacturer TIME：2023-03-02
The full name of pe backsheet film is "waterproof and breathable microporous film", which is characterized by breathability and impermeability. It is a new type of polymer waterproof material in the world, which is widely used in various fields of life, such as: women's sanitary napkins, pad bottom films, baby diapers, etc. This article introduces the ventilation mechanism, hole making mechanism, process flow and characteristic requirements of pe backsheet film.
(1) Breathing mechanism
The microporous membrane itself has countless interconnected micropores, and its pore size is very fine (about 0.01~10pm), which can only pass through water vapor molecules with a particle size of about 0.4nm. too big to pass.
In this way, the water vapor emitted by the human body can effectively diffuse outward through the aperture, while the water droplets cannot penetrate inward, so as to achieve the effect of waterproof and moisture permeability.
(2) Pore-forming mechanism
The main feature is that inorganic fillers (such as calcium carbonate, etc.) are added to the resin, and the principle of forming micropores at the junction of inorganic filler particles (1~10pm) with the plastic film substrate being shaped during the stretching process is used. The size of these micropores is Sub-nanoscale, that is, hundreds of millions of micropores can be distributed in an area of 1 square centimeter. These micropores constitute a channel that allows gas to pass through, so as to realize the function of the PE bottom film being breathable but watertight.
pe backsheet film generally adopts the method of extruding flat film and then stretching. The process flow can be divided into three parts: sheet preparation, stretching and shaping. The production process is: PE raw material + pore-forming agent → extruding sheet → cooling → preheating → stretching → heat setting → cooling → trimming → coiling.
(1) Good mechanical strength, easy to stretch longitudinally and laterally
The mechanical strength of the film mainly refers to the tensile strength, which refers to the highest strength that the film can withstand when it is pulled in a parallel direction, which is subject to the highest tensile force per unit area.
(2) Excellent hydrophobicity
pe backsheet film, also known as "waterproof and breathable microporous film", is characterized by being breathable and impermeable. The performance is closely related to the adsorption of the membrane, which mainly depends on the chemical properties and structure of the membrane material. The hydrophilicity of the film is generally characterized by the method of measuring the contact angle. The pe backsheet film does not contain hydrophilic groups, so it has strong hydrophobicity and can prevent the leakage and splashing of blood, body fluids, and urine.
(3) Comparison of uniform porosity and permeability (determined by nitrogen and oxygen gas exchange experiments)
Porosity refers to the ratio of the volume occupied by voids in the entire membrane to the total volume. The microporous membrane itself has countless interconnected micropores, and its pore size is very fine (about 0.001~1 micron), which can only pass through water vapor molecules with a particle size of about 0.4nm. too large to pass. In this way, the water vapor emitted by the human body can effectively diffuse outward through the aperture, while the water droplets cannot penetrate inward, so as to achieve the effect of waterproof and moisture permeability.
(4) Special morphological structure
The morphological structure of the membrane can be characterized using electron microscopy.
pe backsheet film, also known as breathing film, is more and more widely used in various fields of life because of its soft skin-friendly, high tensile strength and good moisture permeability. Understanding the PE bottom film is conducive to better use of it.
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