What issues should be paid attention to during the design of polypropylene staple fiber?
In addition to the general spinning rheology considerations, polypropylene staple fibers in the design of large spinning components must also pay attention to:
(1) The distribution density and distribution mode of the orifice of the spinneret should not only ensure the normal spinning without the phenomenon of injection, but also ensure the compact size of the spinneret and reduce the cost of the equipment under the premise of ensuring a certain production capacity. . This is especially important for shaped holes or composite orifices.
(2) In the design of the cooling method of the yarn, it is necessary to have a certain wind speed to ensure the cooling effect, and to minimize the difference between the hole and the hole, especially between the rows and the rows of the spinning holes (rectangular plate) and the inner and outer layers. The difference between (the annular plate).
(3) Since the apparent dryness of the polypropylene melt during spinning is larger than that of other synthetic fibers, the flow velocity of the melt in the passage of the melt from the outlet of the metering pump to the population of each orifice should be as uniform as possible. There is no sudden increase in speed and deceleration.
(4) The hole diameter to length to diameter ratio of the spinning orifice should not only take into account the shear rate that the melt rheology can withstand (negligible in short-spinning low-speed spinning), but also consider the spinning draw ratio (spinning) The hole outlet to the godet or the first drafting roller should not be too large to cause the melt to break and the spinning stretch cannot proceed normally. This should be especially noted when spinning low-strength, high-stretch fibers.
The above aspects are mutually influential in the actual operation, and must be considered in order to have a perfect overall design in the design of the polypropylene staple fiber large spinning assembly.
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