Meltblown nonwovens are mainly used to filter μm-level particles such as dust, bacteria, and haze, and can be called the "heart" of masks. Made of polypropylene microfibers randomly distributed and bonded together, they are white, smooth, and soft. The particle size of the raw material fiber is 0.3-7.0μm. The random distribution of the fibers provides more thermal bonding opportunities between the fibers, so that the meltblown gas filtration system has a higher specific surface area and a higher porosity (≥75%). After high-pressure electret electrostatic treatment, it has the characteristics of low resistance, high efficiency, and high dust holding capacity.
Alias: meltblown cloth, mask cloth, PP non-woven fabric
Material: Plastic polypropylene (PP) meltblown special material
Most of the traditional filtration systems use ordinary meltblown nonwovens, etc., which have weak filtering effects and cannot effectively filter fine particles and bacteria in the air; after research, the electret process is adopted, that is, the polypropylene nonwoven fabric that adds electret materials during processing and undergoes electret treatment has higher filtering efficiency.
Compared with the general textile filtration system, the polypropylene meltblown nonwoven fabric produced by the electret process improves the electrostatic adsorption effect on the basis of mechanical collection principles such as impact, blocking and diffusion, which not only improves the filtering efficiency, but also increases the filtering resistance. In addition, it also has antibacterial and antibacterial properties.
Material of meltblown polypropylene PP particles
The melt index (MFI) of polypropylene particles is directly related to the super-strength and bursting strength of meltblown nonwovens.
The lower the relative molecular weight of the polymer, the higher the melt flow index (MFI), the lower the melt viscosity, and the more suitable it is for the poor yarn separation effect of the meltblown process.
The higher the melt index, the lower the super strength of the single chemical fiber produced by the meltblown, and the super strength of the fiber web is also low.
In actual production, should polypropylene with a large or small MFI be used?
Small MFI: can produce meltblown nonwovens with higher super strength.
Large MFI: high production volume and low energy consumption. Therefore, the current trend is to use higher MFI raw materials.
Meltblown grade polypropylene PP granular material: MFI>1500
In other words, if you find that the meltblown cloth produced is "too brittle", first look at the melt index of the raw material. How to actually look at this parameter depends on where you buy the raw materials.
1. Meltblown process
Reasons for the small vortex of warm air:
The hot air velocity increases;
The denser the fiber diameter;
The relative strength of single fiber increases;
The bonding effect between fibers in the fiber web increases, and the compressive strength of nonwoven fabric increases.
The warm air vortex velocity is controlled between 0.08-0.2. The air velocity must be stable, not high or low at times, and the flow rate will produce a "shot" phenomenon if it is too alternating. Because the current market air path equipment is diverse and the performance is uneven, problems must be differentiated, and meltblown process parameters should be adjusted flexibly.
2. Meltblown material pipe temperature
The higher the temperature, the lower the melt viscosity and the denser the fiber
However, too low melt viscosity will lead to excessive yarn separation of melt strips, and the slightly shorter and finer fibers produced will float into the air and cannot be collected. Therefore, the polymer melt viscosity in the meltblown process is not the lower the better. In this case, there will sometimes be "flying flowers", which are undispersed fibers in the air.
The pipe temperature, flange temperature, and elbow temperature should be kept at a level, and these three temperatures must not deviate too much.
Wenzhou Tianye Plastic Machinery Co., Ltd. was established in March 2009 and is a manufacturer of complete sets of machinery and equipment such as PP and PE woven bags, mesh bags, and ton bags.