Product Overview
Glycerol Monostearate (GMS) is a highly efficient and multifunctional lubricant widely used in PVC processing. It primarily functions as an internal lubricant while also providing a degree of external lubrication, making it an important additive in modern PVC formulations.
GMS plays a vital role in improving processing efficiency by reducing melt viscosity, minimizing frictional heat generation, and enhancing the surface finish of final PVC products. It also improves demolding performance, ensuring smoother production cycles and higher product quality.
Due to its non-ionic nature and excellent compatibility with PVC, GMS is particularly suitable for transparent PVC applications and high-filler formulations.
GMS is free from heavy metals and, when used in compliant formulations, helps manufacturers meet environmental and regulatory standards such as RoHS and REACH. It can be used as an alternative to traditional lubricants such as calcium stearate or in combination with them to achieve the desired lubrication balance.
Key Specifications
Typical quality parameters include:
- Monoglyceride Content: ≥ 90% (High purity grade) / Industrial grade ≥ 40–50%
- Glycerol Content: ≤ 1–2%
- Free Fatty Acid: ≤ 2–3%
- Ash Content: ≤ 0.1 – 0.5%
- Acid Value: ≤ 2 – 5 mg KOH/g
- Iodine Value: ≤ 3 g I₂/100 g
- Saponification Value: 150 – 165 mg KOH/g
Applications and Functional Benefits
1. Internal Lubrication
GMS primarily acts as an internal lubricant within PVC formulations.
Key benefits include:
- Reduces friction between PVC molecular chains in the melt phase
- Improves melt flow and promotes uniform plasticization
- Lowers melt viscosity, reducing processing energy consumption
- Minimizes mechanical load on processing equipment
- Helps prevent overheating and degradation during processing, particularly in extruders, screws, and barrels
2. External Lubrication Performance
In addition to internal lubrication, GMS also contributes to external lubrication.
This includes:
- Forming a lubricating layer between the PVC melt and metal surfaces of processing equipment
- Preventing adhesion of molten material to die heads, rollers, and screws
- Improving surface smoothness and gloss of finished products
- Facilitating easier mold release and demolding
3. Additional Functional Advantages
GMS provides several additional processing advantages in PVC formulations:
Improved Degassing
Helps release trapped gases during processing, improving product consistency and surface quality.
Reduced Migration
Exhibits good compatibility with PVC, minimizing additive migration and maintaining long-term product performance.
Enhanced Thermal Stability
Works alongside stabilizers to reduce thermal degradation during high-temperature processing.
Support for Transparent PVC
Compared with some metal-soap lubricants, GMS has a lower impact on transparency, making it suitable for clear PVC products.
Typical Application Areas
GMS is widely used across various PVC manufacturing sectors.
Rigid PVC (RPVC)
Common applications include:
- PVC pipes and fittings
- Window and door profiles
- Rigid sheets and films
- Injection molded products such as bottle caps
In rigid PVC, GMS primarily functions as an internal lubricant to improve melt processing.
Soft PVC (SPVC)
Used in:
- Electrical cable insulation and jacketing
- Flexible films and sheets
- Artificial leather
- Hoses and tubing
- Toys and sealing products
In soft PVC, GMS works alongside plasticizers to balance lubrication performance.
Transparent PVC Products
Suitable for:
- Transparent packaging materials
- Plastic cards
- Decorative sheets
These applications benefit from GMS’s low impact on optical clarity.
Food-Contact PVC Applications
GMS can be used in formulations designed for:
- Food packaging films
- Bottle cap gaskets
- Drinking water pipes
(Subject to regulatory compliance and formulation approval.)
Recommended Dosage
Typical dosage levels range from:
0.2 – 1.5 phr (parts per hundred resin)
The exact dosage depends on several factors, including:
- PVC resin type
- Processing method (extrusion, injection molding, calendering)
- Presence of other additives such as stabilizers and plasticizers
- Desired balance between internal and external lubrication
Optimization through formulation trials is recommended for best results.
Packaging and Storage
Packaging
GMS is typically supplied in:
- 25 kg bags
Common packaging materials include kraft paper bags or composite paper bags lined with polyethylene (PE) to ensure moisture protection during transport and storage.
Storage Conditions
For optimal product stability:
- Store in a cool, dry, and well-ventilated warehouse
- Avoid exposure to high temperatures and direct sunlight
- Keep away from heat sources and open flames
Recommended storage temperature: below 30°C
Shelf Life: Up to 24 months when stored under proper conditions.
