The performance of melt blown products mainly refers to their physical and mechanical properties, such as strength, breathability, fiber diameter, etc. Due to the complexity of the melt blown process, there are many influencing factors. Today, the editor will briefly analyze the reasons for the lack of toughness in meltblown fabrics. If you cannot explain it well, please provide more guidance and suggestions!
Melt blown grade polypropylene PP particle raw material
The melt index (MFI) of polypropylene particles is directly related to the tensile strength and bursting strength of melt blown nonwoven fabrics.The lower the molecular weight of the polymer, the higher the melt flow index (MFI), and the lower the melt viscosity, making it more suitable for the weaker.
Stretching effect in melt spraying processes
The higher the melt index, the lower the strength of the melt blown single fiber and the lower the strength of the fiber web.
In actual production, should polypropylene with high MFI or low MFI be used?
MFI small: capable of producing melt blown nonwoven fabrics with high strength.
MFI large: high output, low energy consumption. Therefore, the current trend is to use higher MFI raw materials.
Melt blown grade polypropylene PP pellets: MFI>1500
That is to say, if you find that the produced meltblown fabric is “too brittle”, first check the melt index of the raw materials. The specific way to view this parameter depends on where you purchased the raw materials from.
Melt blown process
The reason why the airflow of hot air is too small:
The velocity of hot air increases;
The finer the fiber diameter;
The relative strength of single fibers increases;
The bonding effect between fibers in the web increases, and the strength of the non-woven fabric increases.
The velocity of the hot air flow is controlled between 0.08-0.2. The air flow rate must be constant and cannot fluctuate rapidly. If the flow rate is too high, it will form a “shot” phenomenon. Due to the wide variety of gas supply equipment in the current market and uneven performance, problems should be treated differently and the melt spraying process parameters should be flexibly adjusted.
Temperature of melt blown mold head
The higher the temperature, the lower the viscosity of the melt, and the finer the fibers
However, a low viscosity of the melt can cause excessive stretching of the melt filaments, resulting in ultra short and ultrafine fibers that scatter into the air and cannot be collected. Therefore, the viscosity of the polymer melt in the melt spraying process is not necessarily better when it is lower. At times like this, there may also be a phenomenon of ‘flying flowers’, where there are no fibers that have gathered or dispersed in the air.
The temperature of the mold head, flange, and elbow should be maintained at a level line, and these three temperatures must not deviate too much.
The above is an analysis of the reasons why meltblown fabrics become brittle and have insufficient tensile strength. It depends on the strength of the fabric’s brittleness, and the production process should be adjusted reasonably. The production of meltblown fabrics is not difficult, but the difficulty lies in the meltblown forming process, which requires a certain amount of experience accumulation to adjust equipment operation. For friends who really don’t understand, they can find a reliable machine adjustment master or contact the editor to discuss and encourage together!
Dongguan Liansheng Nonwoven Fabric Co., Ltd., a manufacturer of non-woven fabrics and non-woven fabrics, is worthy of your trust!
Post time: Dec-14-2024