Compound CaCO3 is the most versatile filler masterbatch which is used to save a lot of production costs. PP Raffia is a common application of compound CaCO3. It is widely used in packaging industry, especially industrial and agriculture packaging production such as FIBC containers, laminated PP bags or greenhouse twines. No matter how strictly the masterbatch manufacturers try to control the manufacturing process, there is always a possibility for some issues to happen. Here are 7 common obstacles that usually occur while applying PP masterbatch into Raffia production.
How to prevent excessive water carryover in producing PP Raffia from compound CaCO3
Possible Causes:
- Processing temperature too high
- Water Quench batch temperature too high
Corrective Actions:
- Adjust the temperature profile in extruder zones
- Lower the quench tank temperature
- Review the concentrate and regrind level
- Rearrange the mechanical brush positions
- Slow down the speeds
Tape/Yarn breakage – a common issue in processing compound CaCO3
Possible Causes:
- The temperature during the process of melting compound CaCO3 is too low
- Godet temperature too low
- Draw speed too high
Corrective Actions:
- Increase the melting temperature and optimize the extruder temperature profile; also review the godet temperature
- Review the A/O level in PP masterbatch
- Alter the draw ratio
- Check the regrind level
Low tenacity could easily happened in molding compound CaCO3
Possible Causes:
- PP-MFR too high. MFR stands for the melt flow rate – an index used to measure the molecular weight of polypropylene. By knowing the molecular weight of the MFR of PP compound CaCO3, masterbatch manufacturer will be able to know whether the molten raw materials will easily flow during the processing. The high MFR indicates for an ease in processing the PP masterbatch by injection molding or blow molding. However, if the MFR is too high, some physical and mechanical properties of the plastic can be affected negatively, for example, the impact resistance.
- Residual elongation
Corrective Actions:
- Increase stretch ratio
- Increase oven/hot plate temperature
- Review the MFR of the starting PP compound CaCO3. In general, the lower the MFR is, the higher the tenacity that finished products can achieve is. However, the expense of back-pressure is higher. In most cases, higher back pressure is not necessary and can cause adverse effects on screw recovery. Back pressure is recommended to be in the range from 50 to 100 psi.
- Adjust the draw ratio
- Lower the draw temperature
Excessive Shrinkage during compound CaCO3 is mainly caused by setting wrong temperature
Possible Causes:
- Heat set temperature too low. Heat set temperature, which is also called as molding temperature, is usually between 60oF to 150oF. Applying heat into the molding step is required. However, the proper temperature should be carefully controlled and adjusted. If the temperature is too low, there will be flow marks, weld lines, lamination, brittle parts, voids, short shots, and core sticking appearing on the finished product’s surfaces. However, when the temperature is too high, there will be some problems related to the shrinkage, warpage, sinking or cavity sticking.
- Draw ratio too high
Corrective Actions:
- Alter the draw roll temperature to reflect higher set temperature
- Reduce the draw ratio
High elongation of PP Raffia generated by compound CaCO3
Possible Causes:
- Water Quench bath temperature too high
- Oven/hot plate temperature too low. This problem is likely to happen when hot plate welding is included in the processing procedure. Hot plate welding is widely used with the purpose of joining the products produced by compound CaCO3. The plastic parts, especially their surfaces, are softened in contacting with hot place and joined together under proper pressure.
- High air gap
- Stretch ratio too low
Corrective Actions:
- Adjust quench tank temperature
- Increase oven/hot plate temperature
- Increase stretch ratio
- Reduce air gap
Fibrillation of tapes – common issue in producing tapes/yarn from compound CaCO3
Fibrillation is a common issue regarding to the PP Raffia, not only in the production but this problem can also happen in delivery or using time.
Possible Causes:
- Stretch ratio too high: When the compound CaCO3 is stretched with high force, fibrillation easily happens.
- Winder tension not compatible
Corrective Actions:
- Check sharpness of blades on spacer
- Reduce stretch ratio
- Check wrinkles in the tape
- Check winder tension