As one of the fastest growing fields in the nonwoven industry, nonwoven fabric materials for filtration have a very wide range of applications, such as petroleum, chemical, energy, environment, food and beverage, biopharmaceutical, medical, marine, military and other fields.The application of nonwoven fabric materials in the field of filtration has many excellent characteristics, including high filtration efficiency, easy production, low cost, low price, easy to compound with other kinds of materials, and easy to carry out deep processing such as pleating and molding in the production line. Therefore, the nonwoven fabric materials for filtration can gradually replace the traditional filtration materials, and their consumption will be more and more large.
In recent years, the rapid growth of consumers' demand for health and safety water and the increasing awareness of environmental protection have well driven the growth of global non-woven filter media market.At the same time, the global and China's increasingly stringent laws and regulations, industry, transportation and rapid development of infrastructure construction drive the demand for nonwoven filter media is also growing rapidly.
In terms of regions, due to the highly industrialized economy of North America, Europe and other developed countries and regions and their long-term attention to environmental protection, they will continue to maintain the leading position in the main market of nonwoven filter materials, and focus on technology upgrading to develop more efficient filter materials. However, due to the high degree of market saturation, the growth rate of developed countries and regions will slow down.
Compared with North America and other economically developed regions, the rapid growth of industry and economy in Asia Pacific countries, as well as the increasing environmental problems, are making it the main position of global environmental protection filtration industry in the next few years.Among them, the main driving force of growth comes from China, India and other countries.
China is the most important filter material market in the Asia Pacific region, with a huge manufacturing base.In the past few years, China's nonwoven filter industry has made great progress, and the product quality has also been greatly improved. The driving force of the downstream domestic demand market has provided the main driving force for the continuous growth of China's filter material market.
Factors affecting filtration efficiency:
01.Structure of nonwoven materials
In general, the filter material is required to be able to block or adsorb particles on the structure, and ensure a certain amount of gas to pass smoothly. The filtration effect of filter material is realized through its internal pore channels, so the pore size and its distribution have a great influence on the filtration efficiency of the material.
The results show that the smaller the porosity of nonwoven material is, the higher the filtration efficiency is. This is because when the porosity of the material decreases, the space occupied by the fiber in the whole material structure increases, the chances of contact with particles increase, and the ability to capture particles increases, so the filtration efficiency of the material is improved.As far as the nonwoven materials for filtration are concerned, their structure is closely related to the filtration efficiency.
02.Particle size and shape
The size and shape of particles affect the filtration efficiency of filter materials. When the particle size increases from small to large, the diffusion efficiency decreases gradually. Smaller particles will deposit on the fiber first due to diffusion, while larger particles will also deposit on the fiber due to interception and inertia.
03.Filtration speed
When the filtration speed is small, the filtration efficiency decreases with the increase of filtration speed.For the same diameter fiber, with the decrease of particle diameter, the more difficult it is for the fiber to capture particles, and the particle penetration rate increases, which leads to the decrease of filtration efficiency; for the same diameter particle, with the increase of fiber diameter, the specific surface area of the fiber decreases, the ability to capture particles decreases, and the particle penetration rate increases, which leads to the decrease of filtration efficiency.
04.Temperature and humidity
Filter materials mainly rely on Brownian diffusion, interception, inertial collision, gravity deposition and other mechanical effects to filter particles in the air.When the air is filtered, the diffusion degree of particles will increase with the increase of temperature, but the viscosity of the gas will also increase with the increase of temperature. Due to inertia and gravity, the particles with larger particle size are not easy to deposit on the fiber, and the filtering effect will decrease significantly. After increasing the humidity of the filtered air, the diffusion degree of particles will increase, and the filtration effect will also decrease significantly.
Performance index of filter material
01.Aperture
The pore size of filter materials and products are characterized by pore size (μ m), but there is no direct relationship between pore size and filtration accuracy.There is a unified standard for the measurement of pore size, that is, the filter material is immersed in the test solution, and a certain pressure gas is applied at the end of the filter material. The gas overflows from the other end in the form of bubbles, and the micro pressure value of bubbles at the overflow point is used to characterize the pore size.The formula is D = 4 S / P
In the formula: D - aperture;
S - surface tension of test fluid;
P - micro pressure value of overflow point.
02.Air permeability
Permeability is an index to measure the performance of filter materials, which refers to the average air flow per unit area of filter materials under the action of unit pressure difference.Permeability is a direct factor affecting the filtration performance of products, which is mostly characterized by the resistance when a certain amount of gas passes through a certain area of filter material.
03.Compatibility
The filter material will also be affected by the working liquid. If it is incompatible with the working liquid, the filter material is likely to soften and melt; the performance of the filter material will also change under the action of acid, alkali and other chemical reagents, such as embrittlement, softening, swelling and decomposition, which will seriously affect the performance of the filter material.
