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What Is The Difference Between PE Waterproof And Breathable Film And EPTFE Waterproof And Breathable Film?
- 2023-09-14 11:07:23-

PE waterproof and breathable film mainly consists of three layers: PP spunbonded non-woven fabric, PE polymer breathable film, and PP spunbonded non-woven fabric. The main function of spunbonded non-woven fabric is to enhance tensile strength and hydrostatic pressure, as well as protect the middle layer (breathable film). The true breathability mainly relies on the middle layer PE polymer breathable film.
The so-called PE macromolecule breathable film is a kind of functional inorganic compound evenly added into the polyolefin raw material to make the product produce pores due to high tension in the film forming process, so as to have breathable and moisture conductive functions; In short, the functions of breathable film are: water resistance and breathability (moisture), taking the most commonly used PE as the carrier for example.
The principle of breathable film formation: PE+CaCO3 (master batch) - film formation - stretching - breathable film
PE breathable film is made by blending around 50% special calcium carbonate into LDPE/LLDPE polyethylene resin carrier, extruding it into a film, and then stretching it at a certain rate. Due to the fact that polyethylene resin is a thermoplastic material that can be stretched and crystallized under certain conditions, the interface between the polymer and calcium carbonate particles peels off during stretching, forming interconnected and winding pores or channels around the calcium carbonate particles. It is these pores and channels that endow the film with breathable (wet) function, thereby communicating the environment on both sides of the film.
The working principle of PE waterproof and breathable film:
For inner and outer layers:
In the state of water vapor, water particles are very small, and according to the principle of capillary movement, they can smoothly penetrate the capillary to the other side, resulting in breathability. When water vapor condenses into water droplets, the particles become larger. Due to the surface tension of the water droplets (water molecules "pull and resist" each other), the water molecules cannot smoothly detach from the water droplets and penetrate to the other side, which prevents water infiltration and makes the permeable membrane waterproof.
For the middle layer:
Ventilation principle: When the concentration of water vapor on one side of the film is greater than that on the other side of the film, a humidity gradient pressure difference is formed. This provides the basic conditions for gas (vapor) convection, which leads to a relative balance in the humidity environment on both sides of the film due to the formation of convection.
Waterproof principle: Waterproof can also be said to be waterproof, because there are many pathways in the film, and the zigzag channels formed by it have a large "aspect ratio" (L/D) value, which can be understood as capillaries. So, under the same liquid (such as water) and pressure, as long as the liquid column height of the capillary is less than the length of the capillary, it can be ensured that the liquid will not leak out.
Therefore, the water resistance of the film directly depends on the pore size and path length of the breathable film. This performance can usually be measured by water pressure resistance. When the water pressure exceeds the water pressure resistance value that the microporous membrane can withstand, water will leak out.
Application of PE waterproof and breathable film:
1. Personal hygiene and care products: such as women's sanitary napkins, baby diapers, pads, diapers, etc.
2. Medical field: Medical and surgical disposable items, such as surgical uniforms, isolation suits, protective clothing, etc.
3. In the field of architecture: While strengthening the water tightness of buildings, it enables the rapid discharge of structural water vapor, avoids the growth of roof mold, and improves the air quality of living rooms.
EPTFE waterproof breathable membrane (expanded PTFE) is called polytetrafluoroethylene, also known as Weiersi waterproof membrane, which has very good chemical stability, can withstand the corrosion of strong acids and alkalis, and has a wide temperature tolerance. Therefore, PTFE has significant advantages compared to other filtering materials.
Film forming principle:
The current method for preparing EPTFE waterproof and breathable film is the biaxial stretching method. After the dry PTFE fine powder is fully mixed with additives, it enters the extruder. The powder is pushed and extruded into PTFE strips, which are then rolled into a membrane under a rolling machine. Then, it is heated and evaporated to remove the additives, and subjected to biaxial stretching. Due to the tensile effect, the PTFE fibrillar structure undergoes separation, forming a special node crack structure.
EPTFE waterproof and breathable film with a thickness of 8-180 after biaxial stretching μ m. The commonly used ones are 10-60 μ m. Aperture within 0.1 μ m-10 μ m. Biaxially stretched PTFE film has a relatively soft texture and low mechanical strength. It is often compounded with non-woven fabric during use to achieve reinforcement.
The working principle of ePTFE waterproof and breathable film:
1. Waterproof: Micropores of 0.1-0.5 microns, with a pore size less than 10000 times that of water droplets, with protection levels of IP67 and IP68, preventing water from passing through, effectively protecting sensitive components, avoiding liquid erosion, and improving product service life.
2. Breathability: The pore size of the micropores is 700 times larger than that of water vapor, which is waterproof and allows air to pass smoothly. It can effectively dissipate heat, prevent fogging on the inner wall of the product, and balance the air pressure inside and outside the space.
3. Dust prevention: The microporous channels form a network three-dimensional structure within the membrane, with uniform and dense distribution of micropores, allowing dust to encounter obstacles and achieve effective dust prevention effects. The minimum size of particles can be captured is 0.1 micrometers.
EPTFE membrane application range:
1. Consumer electronics: electric shavers, electric toothbrush, water absorbers, electric irons for tourism; Sports Watch; LCD TV for bathroom, control box for bathroom, gas igniter, gas meter, milk bottle, hearing aid, household food bottle cap, household liquid bottle cap, air conditioner, vacuum cleaner, stone cutting machine, waterproof electronic scale, waterproof camera, waterproof digital camera, underwater equipment and testing instruments, ink cartridge and selenium drum industrial printer, hard disk, inductive skateboard and air pollutant testing equipment, large electrolytic capacitor, etc.
2. Automotive: automotive instruments and meters, automotive drive control ECU, automotive lights, oxygen sensors, gearbox sensors, gas detectors, heat flow meters, etc
3. LED outdoor lighting fixtures: LED street lights, LED wall washing lights, projection lights, buried lights, underwater lights, mining lights, landscape lights, decorative lights, alarm lights, etc
4. Solar photovoltaic category: solar junction box, combiner box, solar panel heat collector, inverter, outdoor power supply, outdoor charger, battery, mobile phone battery, battery, LED drive power supply, combiner, filter, etc
5. 5G communication equipment category: communication base station antenna, waterproof mobile phone and intercom, base station electronic components, base station control unit, RRU, BBU, wireless AP, military communication radio, radar, outdoor GPS, RFID equipment, ODF box, electrical box control cabinet, safety box, etc
6. Packaging: Chemical liquid bottle caps, agricultural pharmaceutical bottle caps, industrial liquid packaging, chemical packaging, agricultural pharmaceutical packaging, pollution control agent packaging, etc