The larger the groove depth ratio of the screw, the better.
The groove depth ratio (OD/ID) of the screw is the most important parameter to characterize the output and performance of the equipment, that’s because if a pair of parallel screws are fully meshed, the center distance between the two screws is generally fixed, so the higher the groove depth ratio of the screw shaft, the larger the volume of the screw, and the higher the relative output.
The greater the groove depth ratio, the greater the torque borne by the core shaft, therefore, the processing requirements for the material of the equipment are higher, However, the larger the groove depth ratio, the mixing effect of the screw is poor. Generally in order to improve the compounding/mixing effect, when the groove depth ratio is large, some special meshing elements (such as three-head meshing block, SME ZME TME, etc.) must be taken to increase the compounding/mixing effect.
The higher the groove depth ratio (OD/ID), the higher the output, but the worse the mixing effect. The research shows that: the optimized groove depth ratio (OD/ID) coefficient is 1.55, which can guarantee the output and take into account of the compounding/mixing effect.
The thinner the filter, the better.
The finer filter does ensure the control of the fineness of pigments in color masterbatch products. However, if the problem of pigment dispersion is not effectively solved, and only rely on the role of the filter screen to ensure the quality of products, then the consequence will be frequent replacement of the filter screen, resulting in an increase in parking time, seriously affecting the normal performance of production capacity.
What’s more, too long machine pause and frequent net changing will cause more materials to be detained in the high-temperature machine barrel for a long time, and this part of the resin material is very likely to cause deep degradation and bring unexpected harm to the application. A long time of high temperature retention will also lead to the increase of color difference.
Therefore, suitable filters should be selected for different products, for example: for spinning grade masterbatches, the finest filter should be selected; For such Injection grade masterbatch, a thicker filter should be selected, thus not only ensures product quality but also improves production.
When some color masterbatch manufacturers encounter the problem of product dispersion. Their solution is simple: repeated extrusion and granulation, twice once, three times, or even more. such an operation is regardless of the control of production costs, and it is not in line with the concept of low-carbon environmental protection and sustainable development in today’s society.
Moreover, the longer the plastic stays in the high temperature environment, it will cause great damage to the physical properties of plastics and pigments, especially the pigments, and the hue will change obviously.
Adding more lubricant is better.
In order to unilaterally pursue the appearance brightness of color masterbatch products and improve product appearance, continue to increase the amount of lubricants in the formula, and some even increase the proportion of stearate to 5% or more.
However, it is precisely because the excessive addition of low molecular weight components will quickly reduce the total viscosity of the dispersion system, and then seriously affect the dispersion results due to the lack of viscosity shearing; in addition, the addition of too many low molecular weight / low melting point substances will also affect the physical properties of the products to some extent.
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