Meltblown nonwovens are one of the polymer one-step forming techniques, beginning in the early 1950s. At that time, the US Naval Laboratory, with government funding, developed a filter material with ultra-fine filtration effect in order to collect radioactive particles in the upper atmosphere. After several years of hard work, the research team succeeded in inventing a process known as the pioneer of today's meltblown woven fabrics, which can produce ultra-fine filter materials. In the mid-1960s, Exxon began research on meltblown nonwoven technology and succeeded in producing microfibers five years later. Other companies have also developed their own meltblown nonwoven technologies, such as 3M in the US, Freudenberg in Germany, Asahi Kasei in Japan, and NKK.
As early as in the mid-1970s, China began the research on meltblown nonwoven technology by the Shanghai Textile Science Research Institute. It took only two years to test the successful polypropylene meltblown nonwoven fabric, and after a few years, the meltblown nonwoven fabric Technology has been promoted and applied in some areas of China, and dozens of simple domestic melt-blown nonwoven production lines have been put into use.
In the 1990s, China, Tianjin, Anhui and Jiangsu introduced melt-blown nonwoven technology and equipment, which further promoted the application of melt-blown nonwovens in the field of filtration in China.
The filter material is the earliest application field of polypropylene melt-blown nonwoven fabric, and the demand for new filter materials has promoted the development of polypropylene melt-blown nonwoven fabric. At present, the filter material is still the largest application field of polypropylene melt-blown nonwoven fabric. The world's melt-blown nonwoven fabric is used for filter materials of about 20,000 tons/year, mainly for gas and liquid filtration, of which liquid filtration accounts for 65%. Gas filtration accounts for 35%.
Air Filtration With the rapid development of modern industry, the environmental cleanliness requirements are getting higher and higher. To achieve high levels of air cleanliness, it is necessary to have superior performance filter materials. At present, most of the filters such as high-efficiency and sub-efficient are still using glass fiber filter paper. Although they have the advantages of efficient collection of fine particles, they are dense in structure, small in pores, and small in filtration resistance, and also resistant to glass filter paper. The wrinkle ability is extremely poor, which affects the service life of the filter material. The most deadly thing is that it cannot be destroyed after use and will pollute the environment.
The production process of polypropylene melt-blown nonwoven fabric determines the advantages of fine fiber, fluffy structure, high porosity, good anti-crease ability and good filter material. In particular, due to the raw material characteristics of polypropylene, it has a large specific surface area, low density, and good chemical resistance. It is especially suitable for industrial filter materials and is widely used in electronics, pharmaceutical, food, beverage, and chemical industries. By controlling the meltblowing process, a desired web structure and a suitable monofilament fineness distribution can be obtained. Polypropylene meltblown nonwovens are a promising filter material.
According to the five mechanisms of fiber filtration, such as interception effect, inertial effect, diffusion effect, electrostatic effect and gravity effect, polypropylene melt-blown nonwoven fabric can be used as an ideal filter material, especially C, which is unmatched by other filter materials.
Polypropylene meltblown nonwovens are generally used as a filter material. The melt-blown nonwoven fabric has low strength and thinness. In order to increase the strength and dust holding capacity, it is generally combined with materials such as spunbonding and needle punching according to the purification level requirements to obtain a better comprehensive air filtration composite. The material has the characteristics of low initial resistance, high filtration efficiency and large dust holding capacity at the same filtration rate.
Liquid Filtration Polypropylene meltblown nonwoven fabric can be used as a liquid microfiltration membrane after being treated by special processes such as potential rolling. It is widely used in the field of liquid filtration. The term "microfiltration" refers to the filtration of particles having a particle diameter of 0.02 μm to 10 μm, such as bacteria, blood, and macromolecules, which is called microfiltration. The principle is similar to ordinary filtration, and the microfiltration is screen filtration. Under the action of the static pressure difference, particles smaller than the pores of the membrane pass through the membrane, and particles larger than the pores of the membrane are trapped on the membrane surface, so that components of different sizes are separated.
Problems Polypropylene meltblown nonwovens as air filters are currently only able to achieve sub-efficiency levels in China. To replace glass fiber for efficient and ultra-efficient filter materials, there are still some problems. The fiber rigidity is small; the fiber fiber diameter is large; the filtration efficiency is related to the electrostatic effect, especially for particles with a particle size of 0.5 μm or less, so the detection value of the filtration efficiency is poor, that is, unstable.
When the polypropylene melt-blown nonwoven fabric is used as a liquid filter material, it can only be used in the microfiltration category, and the high efficiency of the ultrafiltration membrane is not achieved.
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