Characteristics of plastic modified granulating technology
1.The organic arrangement of building block screw elements to achieve the special efficiency of physical and chemical reactions of materials
a.The components are: conveying block, kneading block, gear plate, counter rotating element, mixer rotor, MITSUBISHI and so on.
b.According to the characteristics of different materials, different screw combinations should be selected to achieve the best results. For example, 1:EPDM/-TPV is to choose a high shear configuration with many kneading blocks, including anti spin and tooth disc components, so as to realize the EPDM's vulcanization and shearing into a special polymer alloy material TPV for a micro island structure in the PP phase. For example, 2: the toughening HI is to choose less kneading blocks and no anti spin. The weak shear configuration combined with the gear tray and other elements to achieve a simple physical melt blending, SBS rubber toughening, and avoiding the degradation of the components.
2.Parabolic section temperature design + head temperature special design to control material melting reaction process
The twin screw extruder is generally composed of 7 to 12 cylinders. Each cylinder has an independent temperature control system. The two ends of the temperature setting are low, the middle is high, the machine head looks at the cooling and the grain cutting state, and achieves the low temperature extrusion as far as possible, obtains the good extrusion appearance.
3.The internal relations and optimal balance of the parameters of the unit
a.Parameters are: main engine speed, host current, feeding speed, cutting speed, melt pressure, melt temperature, section temperature and so on.
b.The main engine speed and current are not directly related, but the higher the rotational speed, the less the electrical loss will be.
c.Feed is usually semi starved, so feed size is directly related to extrusion production capacity.
d.The melt temperature is basically the actual temperature of the material, and there is a gap between the section temperature and the actual material temperature, which is generally 5~20 degrees. This is due to the difference between the temperature probe and the material.
e.The best match and balance of the engine speed, feed speed and section temperature set to maximize the extrusion efficiency and achieve high quality and high production. (considering screw element combination at the same time)
4.The difference between a small model and a large model
The small screw diameter is small, the cavity of the screw and cylinder wall is small, the heat transfer and heat dissipation efficiency is high, and the material dispersion is good. This is why the laboratory can produce very good products, and the same size can not be achieved by large scale generators.
5.Internal relationship between material properties and process characteristics and twin screw extrusion
a.Plastic modification is ever-changing: rubber plastic blending, alloy, filling modification, toughening modification, glass fiber reinforcement, reactive extrusion, etc.
b.Process characteristics: is it a simple physical melting blending or physical reaction extrusion of several raw materials? Is it premixed with raw material or separate feed?
c.According to material properties and process characteristics, a reasonable screw element combination and parameter setting are designed.