Melt-blown nonwoven fabric has become indispensable in various industries, particularly in applications requiring high filtration efficiency and fine fiber structures. One of the critical parameters influencing the quality and performance of melt-blown fabric is the Melt Flow Index (MFI) of the raw materials used.
What is Melt Flow Index (MFI)?
MFI is a measure of the flowability of the molten polymer used in the production of synthetic materials like polypropylene, which is a common choice for melt-blown fabric. It indicates how easily the polymer melts and flows under specified conditions of temperature and pressure. For melt-blown fabric production, polymers with specific MFI ranges are preferred due to their ability to form ultra-fine fibers during extrusion.
Average MFI Range for Raw Materials
The average MFI range required for raw materials used in melt-blown nonwoven fabric production typically varies between 800 and 1600. This range is considered optimal for achieving the desired fiber diameter, which is crucial for the fabric's filtration efficiency and other performance characteristics.
Lower MFI (800-1000): Polymers with lower MFI values tend to have higher molecular weights and viscosity. While they require higher processing temperatures and pressures, they produce finer and more uniform fibers. This is advantageous for applications requiring high filtration performance, such as face mask middle layers.
Higher MFI (1000-1600): Polymers with higher MFI values flow more easily during extrusion, making them easier to process at lower temperatures and pressures. They can still produce fine fibers suitable for applications like sound insulation in cars or oil absorption sheets.

Importance of MFI in Fabric Properties
The MFI of the polymer directly impacts the diameter and distribution of the fibers in the melt-blown fabric. Fine fibers with diameters ranging from 1.6 to 4 micrometers are essential for achieving the fabric's desired properties, including softness, elasticity, and most importantly, efficient filtration performance.
Choosing the Right MFI for Application-Specific Needs
When selecting raw materials for Melt-blown nonwoven fabric production, manufacturers consider the specific requirements of the end applications:
Filtration Efficiency: For applications demanding high filtration efficiency, such as medical face masks, polymers with lower MFI values are preferred to produce finer fibers that can effectively capture small particles.
Mechanical Properties: Polymers with appropriate MFI values also contribute to the fabric's mechanical properties, such as tensile strength and durability, ensuring it meets performance standards across different applications.
In conclusion, the average MFI range of 800 to 1600 for raw materials used in melt-blown nonwoven fabric production plays a crucial role in determining the fabric's quality, performance, and suitability for various applications. Understanding and optimizing MFI allows manufacturers to produce melt-blown fabrics that meet specific filtration requirements while maintaining desirable mechanical properties. This underscores the importance of MFI as a key factor in the production process of melt-blown nonwoven fabrics, contributing to their widespread use in critical industries worldwide.