The PVDF cover with screws by injection molding

What is PVDF?

Characteristics of PVDF

1. Fluorinated resin suitable for injection molding and extrusion (commonly known as thermoplastic Teflon).
2. Excellent chemical resistance, withstanding most chemicals and solvents.
3. Wear-resistant, with high mechanical strength and toughness.
4. Weather-resistant, resistant to ultraviolet rays and nuclear radiation.
5. Good heat resistance and high dielectric strength.
6. Mold-resistant.
7. High impermeability to gases and liquids.
8. Excellent creep resistance during temperature rise.
9. Easy to process via melt processing.
10. Possessing both rigid and flexible forms, with good impact resistance.

Processing Methods of PVDF

1. Extrusion

    

   High-molecular-weight PVDF has good melt strength and can be processed into films, sheets, tubes, rods, power cable insulation sleeves, etc., through extrusion. Depending on the equipment used and the shape of the products, the temperature should be controlled between 210℃ and 290℃, and the molding temperature between 180℃ and 240℃. It is crucial to strictly control the temperature and prevent it from exceeding the melting temperature for an extended period. General screw extruders can be used as extrusion molding equipment.
2. Injection Molding

    

   Low-molecular-weight PVDF features high melt flow rate and can be processed by injection molding. General-purpose injection molding machines are usually adopted, but the barrel, plunger, nozzle and other components must be made of corrosion-resistant Ni-based alloys.
3. Casting

    

   Casting molding uses dimethylacetamide as a solvent to prepare a PVDF solution with a solid content of 20%. The solution is cast on aluminum foil, hot-melted at 205℃–315℃, and then quenched in water to produce continuous, tough films with a thickness of 0.05–0.075mm.
4. Compression Molding

    

   Generally, PVDF pellets are first preheated in an oven or preheating furnace at a temperature of 215℃–235℃. Then, the preheated materials are added to a mold preheated to 180℃–195℃ in advance, pressed and held under a pressure of 14MPa. The pressure holding time depends on the time required for melting and flow. Thick-walled products must be cooled under pressure to below 90℃ before demolding to avoid vacuum bubbles or deformation of the products.
5. Transfer Molding

    

   Typically, materials are first plasticized in an extruder, then transported to a storage cylinder, and injected into the mold via a plunger pump, followed by pressure holding and cooling. Both compression molding and transfer molding are mainly used to produce large-volume, thick-walled products.

Customization Services