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In recent years, non-woven fabrics for filtration have been widely used in industrial filtration, protection, medical and other fields, especially in the new crown epidemic in 2020, and its support for personal protection products has made it the focus of the national and even global epidemic prevention war.

As one of the fastest growing areas in the non-woven industry, non-woven materials for filtration have a very wide range of uses, such as petroleum, chemical, energy, environment, food and beverage, biopharmaceutical, medical, marine, military and other fields. Non-woven materials used in the field of filtration have many excellent characteristics, including high filtration efficiency, easy production, low cost, low price, easy to compound with other types of materials, and easy to be pleated on the production line, compression molding and other deep processing treatment, so the non-woven materials for filtration can gradually replace the traditional filter materials, the amount will be more and more.

In recent years, the rapid growth of consumer demand for healthy and safe water and the increasing awareness of environmental protection have well driven the growth of the global non-woven filter media market. At the same time, the world and China's increasingly stringent laws and regulations, industry, transportation and rapid development of infrastructure construction driven by the demand for non-woven filter media is also growing rapidly.

From a regional perspective, due to the highly industrialized economy and long-term emphasis on environmental protection in developed countries and regions such as North America and Europe, it will continue to maintain the leading position in the most important market for non-woven materials for filtration, and focus on technological upgrades 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 economically developed regions such as North America, the rapid growth of industry and economy in the Asia-Pacific region, as well as the increasing environmental problems, are making it the main position of the global environmental protection filtration industry in the next few years. Among them, the main driving force for growth comes from China, India and other countries.

China is the most important market for filtration materials in the Asia-Pacific region and has a large manufacturing base. China's non-woven filtration industry has made great progress in the past few years, and the product quality has also been greatly improved. The downstream domestic demand market has provided the main driving force for the continuous growth of China's filtration material market.

For example, the government's supervision of automobile carbon emissions has continued to increase, and the automobile after-sales maintenance market has also continued to grow, which has further expanded the market size of non-woven filter media in the transportation field. At present, China has become the largest automotive non-woven filter material market in Asia with the second largest automotive market in the world after the United States. In the fields of iron and steel, metallurgy, cement, chemical industry, electric power and garbage incinerator, a large number of bag dust removal technology is used for dust control in flue gas, which has led to a substantial growth in the market of non-woven high-temperature filter materials.

The ongoing industrialization activities of the Government of India are also driving the development of filtration materials. Thanks to the strong development momentum of the automotive industry, the market size of non-woven materials for filtration in the transportation sector in India is expected to double. In addition, developing countries in the Middle East and Africa, such as Saudi Arabia, are mainly due to the growth of demand for non-woven materials for filtration driven by oil processing, while South Africa is due to the improvement of industrialization and the growth of terminal market demand.

Factors affecting filtration efficiency
1. Structure of non-woven materials
In general, the filter material is required to be structurally capable of blocking or adsorbing particles and ensuring the smooth passage of a certain amount of gas. The filtering effect of the filter material is achieved through its internal pore channels, so the pore size and its distribution have a great influence on the filtration efficiency of the material.
Studies have shown that the smaller the porosity of the non-woven material, the higher the filtration efficiency. This is because when the porosity of the material is reduced, the space occupied by the fibers in the entire material structure is increased, the chance of contact with the particles is increased, and the ability to capture the particles is enhanced, so the filtration efficiency of the material is improved. For non-woven materials for filtration, its structure is closely related to filtration efficiency.

2. Particle size and shape
The size and shape of the particles affect the filtration efficiency of the filter material. The particle size is from small to large, the diffusion efficiency is gradually weakened, the smaller particle size will be deposited on the fiber due to diffusion, the larger particle size will be deposited on the fiber due to interception and inertia.

3. Filtration speed
In the case where the filtration speed is small, the filtration efficiency decreases as the filtration speed increases. For fibers with the same diameter, as the particle diameter decreases, the fibers are less likely to capture particles, and the particle penetration rate increases, resulting in a decrease in filtration efficiency; for particles with the same particle size, as the fiber diameter increases, the fiber specific surface area decreases, the particle capture ability decreases, and the particle penetration rate increases, resulting in a decrease in filtration efficiency.

4. Temperature and humidity
Filter materials mainly rely on Brown 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 the particles will be enhanced when the temperature is increased, but the viscosity of the gas will also increase when the temperature is increased. The particles with larger particle size are not easy to deposit on the fibers due to inertia and gravity, and the filtering effect is obvious. Decreased. After increasing the humidity of the filtered air, the diffusion degree of the particles will increase, and the filtering effect will also be significantly reduced.

Performance index of filter material
The filtration performance indicators of the filter material include pore size, air permeability, compatibility of the filter material, and filtration accuracy.

1. Aperture
Both the filter material and the filter product size are characterized by pore size (μm), but there is no direct relationship between pore size and filtration accuracy. There is a unified standard for the test method of aperture, that is, the filter material is immersed in the test solution, and a certain pressure of gas is applied to the end of the filter material, and the gas overflows from the other end in the form of bubbles, and the micro-pressure value of the bubble at the overflow point is used to characterize the size of the aperture. The calculation formula is: D = 4 S/P
In the formula: D-aperture;
S-surface tension of test fluid;
P-bubble overflow point micro pressure value.

2. Air permeability
The air permeability is an index to measure the performance of the filter material, which refers to the average air flow per unit area of the filter material under the action of the unit pressure difference. Air permeability is a direct factor affecting the filtration performance of the product, which is mostly characterized by the resistance encountered when a certain amount of gas passes through a certain area of filter material.

3. 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 relevant properties of the filter material will also change under the action of acid, alkali and other chemical reagents, resulting in embrittlement, softening, swelling and decomposition, which will seriously affect the performance of the filter material.

The filtration industry with increasingly high standards and requirements poses greater challenges to product innovation. New legislation, more serious environmental issues, and consumers' desire for cleaner water and air will drive continued research and development in the field of filtration. Non-woven materials for filtration must continue to meet the higher requirements of the downstream market for efficiency and performance to stimulate greater vitality.

Source: Jung-International Nonwovens Industry