Precautions

Cleaning of the spinneret for melt spinning

To clean spinnerets you may choose one of the following methods:

1. Calcination: In temperature automatic control furnance，the spinnerets are heated to 450 to 480 ℃， when temperature is over 480℃, a super heated steam get into the chamber and blow out flame to lower the temperature，preventing the spinmerets from deforming.

2. Salt bath: Formed by MaNO3(45%)-NaNO2(45%)-MaOH(10%), salt bath melt temperature is 200 ℃, working temperature is between 450 and 500 ℃. The salt bath acts as strong oxidant at this temperature, it oxidizes polymer into C02 and H20 very quickly in 60 to 90 minutes. After processing in salt bath, salt on spinneret can be washed off by hot water and oxidization membrane can be removed by thin nitric acid. Following by cleaning the spinneret with clear water, ultrasonic cleaning and drying.

3. Procedyne fluid bed: At temperature of 450 to 500 ℃,  hot air stream carries aluminum oxide powder to scour and strip the polymer on spinmeret and makes it dissociation and gasification and discharges into the air( around 70% polymers aredecomposed and form a little carbon particles). Inorganic substances exist on spimnerets such as Ti02 will be distrarged with the air stream. The advantage of this method is that the spinneret can be cleaned voluntarily.

4. TEG: First put the spinmerets in boiling solution containing 15% to 20% NaOH for 2 to 3 hours to remove most of the polymers on spinmnerets. Then put the spimnerets in TEG solution bath of 260 to 280 C for about 12 hours, then cooling. After cooling the spimerets should still be cleaned in alkali and clean water as well as ultrasonic bath, then be dried. The advantage of this method is working temperature not so high, and is suitable for any type of stainless steel spinnerets but needs longer cleaning time.

5. Vacum calcination: Burning in low pressure vacum furnance，All the polymers can be decomposed. This method is convenient and controlled automatically.  After processing, the spimnerets should be cleaned in ultrasonic bath with alkli solution and then in clean water.