The key factor of melt blown cloth not reaching 95 standard: melt blown cloth processing technology!
The possible reasons for the failure of the melt blown cloth to reach the 95 standard are: the raw materials are not up to the standard, the production process parameters of the melt blown cloth are not up to the standard, and the filter level of the melt blown cloth is not up to the standard (the electrostatic adsorption is not up to the standard). The important reason why the melt blown cloth does not reach the 95 standard is that the electrostatic adsorption is not up to the standard!
If you buy the materials that strictly conform to the standard through regular channels, the control of the production and processing technology of the melt blown cloth is particularly important, because the quality of the melt blown cloth will be directly determined by the setting of the production technology and parameters, and there is no problem in the processing technology, so it is no doubt that the filter level of the melt blown cloth wants to reach the standard.
Although the manufacturing of melt blown cloth production equipment is not complicated, the technological problems must be solved. Because this involves the temperature, air pressure, mold, speed and other parameters, so we need to constantly run in and debug, in order to achieve the best results.
1. Ways to improve product strength
a. Increase the flow rate of hot air (the fiber is thin, there are many winding nodes, the stress of the fiber is even, the strength increases, but when it increases to a certain extent, it will decrease);
b. Increase the temperature of hot air (as above);
c. Properly increase the weight of the product (within the scope of internal control);
d. Increase the temperature of die head (die tip) and other areas (the same as a);
e. Reduce production properly;
f. Reduce the DCD properly (not too small, but the cloth brittleness strength will decrease, combined with other parameters);
g. Increase the net bottom suction (the weight of big gram is more obvious);
h. Use melt to refer to lower material.
2. Methods to improve the elongation of products
a. Reduce the flow or temperature of hot air appropriately (the sliding path of node becomes larger and the hand feel becomes hard);
b. Reduce the working temperature of die head (die tip) (as above);
c. Reduce production properly;
d. Increase DCD (more obvious when used with a or b);
e. Reduce the ambient temperature (spinning ambient temperature);
f. Increase the net bottom suction (the effect is not obvious, the weight of big gram is better);
g. Change the fiber angle (change the structure of fiber mesh, not commonly used)
h. Increase the output properly (this method will reduce other physical indexes and is not commonly used).
3. Ways to reduce resistance
a. Reduce the flow rate or temperature of hot air (fiber coarsens, porosity is large, resistance is small, efficiency is poor);
b. Increase DCD (increase the fiber's fluffy, high porosity and poor efficiency);
c. Reduce the spinning environment temperature (fiber cooling fully, structure fluffy, porosity increase, with hot air can achieve the purpose of reducing resistance and improving efficiency);
d. Reduce the suction of the net bottom (the density of the fiber becomes fluffy, the porosity becomes large, and the weight of the big gram is obvious);
e. Reduce the working temperature of heating zone such as die head (die tip) (fiber coarsens, porosity increases);
f. Increase the metering pump (the extrusion volume becomes larger, the fiber becomes thicker, and the porosity increases, which is generally used in the rapid conversion);
g. Reduce the weight properly (within the scope of internal control).
4. Methods to improve filtration efficiency
a. Increase the hot air flow or temperature (increase the fineness of the fiber, reduce the porosity, improve the catching ability, but increase the resistance);
b. Increase the electrostatic voltage (current) (polarization fiber, increase the electrostatic field energy of fiber, improve its adsorption capacity);
c. Adding powder or other electret into the raw material (improving the receiving capacity and storage time of the fiber, making the fiber carry more charge and charge time);
d. Increase the suction of the net bottom (increase the density of the fiber, improve the catching ability of the fiber. Large gram weight is obvious, not commonly used);
e. In the same process, the extrusion volume is smaller, the fiber is thinner and the resistance is higher;
f. Improve the working temperature of die head (die tip) and other areas (melt fluidity is better, fiber is thinner);
g. When the room temperature is higher, the resistance increases obviously and other physical indexes decrease;
h. Increase the amount of powder properly.
5. Methods that can reduce resistance and improve efficiency
a. At the same time of increasing DCD, the flow rate or temperature of hot air should be increased properly, and the suction at the net bottom should be reduced (the fineness and fluffy degree of fiber should be increased);
b. Increase fiber fineness and reduce spinning environment temperature (such as adding cooling air device);
c. At the same time, increase the electrostatic voltage (current) and the amount of powder;
d. Increase the fineness of the fiber and reduce the weight of the fiber (not commonly used).
6. The method of improving both strength and elongation
a. Properly reduce the hot air flow or temperature, reduce the DCD, and properly increase the suction at the bottom of the mesh (used for the physical indexes caused by the high ambient temperature and the high melting finger of raw materials are unqualified);
b. Increase the flow or temperature of hot air, increase the DCD, and reduce the suction at the bottom of the mesh properly (for the physical indexes caused by the low ambient temperature and the low melt index of raw materials are unqualified);
c. Reduce production;
d. Increase the fiber fineness and decrease the spinning temperature.
7. How to reduce CV value of products
a. Correspondingly, the working temperature of each area of die head should be changed (the weight of gram should be increased at a low temperature, otherwise the temperature should be decreased);
b. When the local efficiency, resistance and CV value are inconsistent, the baffle can be added at its position (to improve the local spinning ambient temperature);
c. The CV value of the longitudinal weight is mainly related to the stability of the velocity of the meshing system.
8. Cause of "shot" agglomerated polymer
a. Improper setting of working temperature (too high or too low, generally too high and easy to occur);
b. Raw materials or masterbatch are too dirty (generally the whole cloth surface or large area appears);
c. At the later stage of die head use, the die tip is dirty (sometimes the local wire out is bad or large area appears, can be solved by scraping the die tip with a scraper);
d. There is carbonized material or dirty plug around the die tip to cause wire out