Three Types of PVC Polymerization Aids
1. PVC Terminator (Short-Stopper)
Packaging: 200 kg / 1000 kg per drum
Storage & transport: keep in a sealed container at 0–40°C with adequate ventilation
Shelf life: 6 months
Appearance: milky white uniform emulsion
Active content % (v/v): ≥ 20.0
pH: 6–10
Introduction
This product is used in the PVC polymerisation process to rapidly eliminate free radicals, terminate the polymerisation reaction and improve the quality of PVC resin. Several imported high-efficiency antioxidants are incorporated in the formulation, so the product not only terminates the polymerisation reaction quickly but also noticeably improves the thermal-ageing whiteness of PVC, effectively enhances the intrinsic quality of the resin, and ensures that articles made from the resin do not turn yellow during downstream processing.
Key Features
1. Low dosage and lower overall cost
2. Good heat resistance, improved thermal-ageing whiteness, no yellowing of downstream articles
3. Environmentally friendly, highly efficient and non-toxic additive
Method of Use
1. Add the calculated quantity of this product in the late stage of PVC polymerisation (when the pressure in the late stage of the reaction has dropped by 0.05–0.1 MPa).
2. The dosage generally depends on the customer’s requirements; a recommended dosage of about 800–1200 ppm is suggested (adjust according to the PVC resin grade and the amount of initiator charged).
2. PVC Anti-Fouling (Anti-Caking) Agent
Packaging: 200 kg per drum
Storage & transport: keep in a sealed container at 0–40°C with adequate ventilation
Shelf life: 6 months
Solids content: 5.5 ± 0.5% (standard type); 10.0 ± 0.5% (high-content type)
pH: 12.5 ± 0.3
Iron ion content: ≤ 5 ppm
Viscosity at 25°C: ≤ 10 cP
Specific gravity at 20°C: 1.02 ± 0.01
Freezing point: −1°C
Introduction
This anti-fouling agent protects the inner wall of the polymerisation reactor during PVC polymerisation and has an excellent anti-caking effect. After spraying, it forms a protective layer on the stainless steel surface that keeps materials from sticking to the reactor wall, extends the cleaning cycle, raises equipment utilisation and improves the quality of PVC resin.
Key Features
1. Contains a special polyhydric-phenol-condensed component that provides an even better anti-caking effect.
2. Incorporates special film-forming components such as chitosan, which chelate more firmly with the stainless steel reactor wall.
3. The unique formulation leaves lower COD in the residual wall-coating liquid after spraying.
Method of Use
1. First lower the spray valve; 40 seconds after the spray valve starts rotating, open the steam regulating valve and the steam shut-off valve, and feed steam into the reactor for 50 seconds.
2. After 50 seconds of steam feeding, start the anti-fouling agent pump, open the regulating valve and shut-off valve, and begin coating the reactor. When the charged amount reaches the formulation quantity, stop the pump and close the shut-off valve and regulating valve in turn, then close the upper steam valves in turn.
3. Open the bottom valve (turn it to the steam position), open the lower steam regulating valve and the steam shut-off valve, and feed steam from the bottom of the reactor. After 60 seconds of steam feeding (when the temperature inside the reactor reaches 70–75°C), close the steam regulating valve, the steam shut-off valve and the bottom valve.
4. During the whole coating process, keep the main and auxiliary circulating-water regulating valves open at 4%.
5. To ensure a good coating effect, the spray valve on the reactor must be inspected regularly (a 30-day cycle is recommended). Check whether the nozzles of the spray pipe are blocked (using the difference in the water flow shown by the flowmeter as the basis). A direct monitoring method is to compare with the flushing flow when the spray valve is completely unobstructed. If the flow drops noticeably, the spray valve is blocked and should be inspected and repaired.
Dosage
30 batches – 1.5 kg; 45 batches – 2.5 kg; 70 batches – 4.0 kg; 105 batches – 7.0 kg; 127 batches – 8.0 kg.
3. PVC Heat Stabiliser
Packaging: 50 kg / 200 kg / 1000 kg per drum
Storage & transport: protect from light and heat (below 36°C), protect from freezing (above 0°C), keep away from fire
Shelf life: 6 months
Appearance: milky white uniform emulsion
Active content % (v/v): ≥ 20.0
Density (g/ml): ≥ 0.95
Introduction
This PVC heat stabiliser is a “multi-function in one” product. Using innovative technology and a specific manufacturing process tailored to the actual requirements of the domestic PVC industry, it forms an emulsion with remarkable stability as a heat stabiliser.
Features
Highly efficient, safe, non-toxic, pollution-free and easy to dilute; it disperses quickly once added to the polymerisation reactor. The particle size is fine and uniform, so it can fully and rapidly embed into the pores of PVC grains. As a result, it effectively accelerates the termination of the polymerisation reaction, improves the ageing-whiteness index that characterises the heat stability of PVC resin, and delivers good early-colour performance during the processing of PVC articles.
The heat stabiliser not only meets the user’s quality requirements but is also convenient to use.
Uses
As a “multi-function in one” additive in the production of PVC resin, its combined uses are:
1. As the heat stabiliser of PVC resin — no other heat stabiliser needs to be added to the formulation;
2. As an excellent chain terminator in the late stage of the polymerisation reaction in PVC resin production.
Key Features
1. Excellent heat and light resistance
2. Improves the plasticisation performance of PVC resin and reduces “fish eyes” in articles
3. Minimises the content of non-volatile matter
4. Highly efficient and non-toxic additive
Method of Use
1. Time of addition: add to the reactor in the late stage of polymerisation, when the pressure has dropped by 0.05–0.1 MPa.
2. Dosage: generally about 0.06%–0.08% of the weight of VCM monomer.
