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Main factors affecting the barrier properties of SMS non-woven fabrics
by：Sunshine
2021-04-09
The main factors affecting the barrier properties of SMS non-woven fabrics are as follows:
1. Product quantitative: the larger the quantitative (g/㎡) of the product, or the greater the proportion of the meltblown fiber web, the higher the hydrostatic pressure, but the strength of the product will decrease, and the cost of raw materials will increase. The more energy is consumed, the higher the production cost.
2. Temperature: The higher the temperature of the melt and the drafting wind, the easier it is for the melt stream to be drawn into fine slenderness. The smaller the diameter of the fiber, the smaller the average pore diameter of the product and the higher the hydrostatic pressure.
3. The DCD of the melt blown system: The receiving distance DCD affects the drafting, cooling of the fiber and the density of the product. When the DCD is small, the product has good uniformity, high density, good barrier performance, high hydrostatic pressure, and poor air permeability; when the DCD is large, the product has poor uniformity, multiple threads, low density, poor barrier performance, and low hydrostatic pressure. Good air permeability and good hand feeling. DCD has an optimal value, generally between 100 and 200 mm.
4. Melt flow rate or spinning pump speed: The diameter of the fiber is directly proportional to the melt flow rate, that is, to the speed of the spinning pump, and inversely proportional to the flow rate (speed) of the drafting air. When producing products of the same specification, reducing the speed of the production line can improve the barrier properties of the product, that is, when the output is low, the product will have a higher hydrostatic pressure, which is a process often used in the production process. To control the barrier performance of the product by changing the flow rate of the melt and the speed of the spinning pump, or the output, is essentially to change the melt flow rate of the spinneret hole.
5. The hole density of the spinneret: when the spinneret with high hole density is used for production, the hydrostatic pressure of the product is higher than that of the product produced by the spinneret with a lower hole density. The essence is that under the same spinning pump speed, the single-hole flow rate of the high-hole density spinneret is small, and the fiber is finer. At present, the hole density of the general domestic melt blown system is 35 to 42 inches, and the highest is 50 per inch; that is, it is equivalent to 1378 to 1654 per meter, and the highest is 1969 per meter.
6. The uniformity and fiber fineness of the spunbond web: the uniformity of the spunbond web has a great influence on the barrier performance of the product. The worse the uniformity, the more discrete the hydrostatic pressure distribution; and the fiber fineness determines The covering property and average pore diameter of the fiber web, the smaller the fiber diameter, the better the barrier performance of the product.
7. Finishing processing: When the product is being cut off-line, if the tension is not properly controlled, excessive winding tension will damage the structure and barrier properties of the product. Similarly, after finishing the product will also affect the barrier performance of the product. For example, during antistatic finishing, if the finishing agent contaminates the meltblown layer, the barrier performance will decrease or even disappear. The finishing process of the product will not only affect the hydrostatic pressure of the product, but also affect the physical properties of the product, such as the decrease in breaking strength, the reduction of elongation, and the deterioration of hand feeling.
8. Raw materials: The flow characteristics of raw materials will affect the quality of the product. The higher the MFI, the better the fluidity of the melt, the easier it is to draw the trickle of the melt, and the better the barrier performance of the product. The MFI of currently commonly used polypropylene (PP) raw materials is between 1200 and 1500.
9. Environment: Melt-blown fiber web is self-adhesive by waste heat to become melt-blown cloth. The temperature of the environment will affect the cooling effect. The lower the temperature, the faster the cooling of the melt-blown cloth and the better product quality. It is not easy to appear 'crystal points'. Therefore, for melt blown systems, products produced in winter or at night will be better products produced in summer or during the day. Some melt blown systems are equipped with cooling devices, the biggest advantage is that the environmental conditions are stabilized, crystal spots rarely appear, and the controllability of product quality is improved.
1. Product quantitative: the larger the quantitative (g/㎡) of the product, or the greater the proportion of the meltblown fiber web, the higher the hydrostatic pressure, but the strength of the product will decrease, and the cost of raw materials will increase. The more energy is consumed, the higher the production cost.
2. Temperature: The higher the temperature of the melt and the drafting wind, the easier it is for the melt stream to be drawn into fine slenderness. The smaller the diameter of the fiber, the smaller the average pore diameter of the product and the higher the hydrostatic pressure.
3. The DCD of the melt blown system: The receiving distance DCD affects the drafting, cooling of the fiber and the density of the product. When the DCD is small, the product has good uniformity, high density, good barrier performance, high hydrostatic pressure, and poor air permeability; when the DCD is large, the product has poor uniformity, multiple threads, low density, poor barrier performance, and low hydrostatic pressure. Good air permeability and good hand feeling. DCD has an optimal value, generally between 100 and 200 mm.
4. Melt flow rate or spinning pump speed: The diameter of the fiber is directly proportional to the melt flow rate, that is, to the speed of the spinning pump, and inversely proportional to the flow rate (speed) of the drafting air. When producing products of the same specification, reducing the speed of the production line can improve the barrier properties of the product, that is, when the output is low, the product will have a higher hydrostatic pressure, which is a process often used in the production process. To control the barrier performance of the product by changing the flow rate of the melt and the speed of the spinning pump, or the output, is essentially to change the melt flow rate of the spinneret hole.
5. The hole density of the spinneret: when the spinneret with high hole density is used for production, the hydrostatic pressure of the product is higher than that of the product produced by the spinneret with a lower hole density. The essence is that under the same spinning pump speed, the single-hole flow rate of the high-hole density spinneret is small, and the fiber is finer. At present, the hole density of the general domestic melt blown system is 35 to 42 inches, and the highest is 50 per inch; that is, it is equivalent to 1378 to 1654 per meter, and the highest is 1969 per meter.
6. The uniformity and fiber fineness of the spunbond web: the uniformity of the spunbond web has a great influence on the barrier performance of the product. The worse the uniformity, the more discrete the hydrostatic pressure distribution; and the fiber fineness determines The covering property and average pore diameter of the fiber web, the smaller the fiber diameter, the better the barrier performance of the product.
7. Finishing processing: When the product is being cut off-line, if the tension is not properly controlled, excessive winding tension will damage the structure and barrier properties of the product. Similarly, after finishing the product will also affect the barrier performance of the product. For example, during antistatic finishing, if the finishing agent contaminates the meltblown layer, the barrier performance will decrease or even disappear. The finishing process of the product will not only affect the hydrostatic pressure of the product, but also affect the physical properties of the product, such as the decrease in breaking strength, the reduction of elongation, and the deterioration of hand feeling.
8. Raw materials: The flow characteristics of raw materials will affect the quality of the product. The higher the MFI, the better the fluidity of the melt, the easier it is to draw the trickle of the melt, and the better the barrier performance of the product. The MFI of currently commonly used polypropylene (PP) raw materials is between 1200 and 1500.
9. Environment: Melt-blown fiber web is self-adhesive by waste heat to become melt-blown cloth. The temperature of the environment will affect the cooling effect. The lower the temperature, the faster the cooling of the melt-blown cloth and the better product quality. It is not easy to appear 'crystal points'. Therefore, for melt blown systems, products produced in winter or at night will be better products produced in summer or during the day. Some melt blown systems are equipped with cooling devices, the biggest advantage is that the environmental conditions are stabilized, crystal spots rarely appear, and the controllability of product quality is improved.
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