Polypropylene high strength yarns are usually produced by melt spinning. The polypropylene resin is heated and melted by adding it to a vertical or horizontal screw extruder, extruded by a spinneret through a metering pump, and cooled into a fiber in air. Industrially, membrane splitting and fibrillation are used to produce split and split fiber.
The characteristics of polypropylene high-strength melt spinning are: 1 single-head and other pitch screw extruder, in order to adapt to the high viscosity and poor fluidity of the fiber-filled polypropylene, the screw compression ratio is larger, the smaller is 2.8, the measurement The segment is as short as possible, and the screw length to diameter ratio ranges from 20 to 26. 2 Due to the large molecular weight, the melt temperature during spinning is generally higher than the melting point by -130 ° C, and a method such as adding a molecular weight regulator may be used to lower the spinning temperature. 3 The crystallization rate is faster during the cooling molding process, and the cooling temperature should be slightly lower.
Polypropylene high-strength yarn has been used for short-spinning or shrink-spinning, that is, the cooling process after the melt-out of the spinneret is very short, and the ramp can be less than 1 m. For example, a 1 kt staple fiber production line can be placed in a factory with a height of 8 m and a length of 30 m from the steps of spinning, stretching, shaping, crimping and cutting. The investment is low, the efficiency is high, and the cost is reduced.
Polypropylene high-strength ya
