What is Polyvinylidene
Chloride (PVDC)?
Understanding PVDC
Polyvinylidene chloride (PVDC) is a versatile resin known for its excellent oxygen and water vapor barrier properties, flame retardancy, oil resistance, and chemical resistance. Typically, PVDC is copolymerized with other monomers, such as acrylics, to improve its suitability for extrusion and coating applications. Industrially, it's manufactured through suspension or emulsion polymerization processes. Emulsion-polymerized PVDC is commonly used as a coating in its latex form or processed into powder form for resin applications.
Why Does PVDC Have High Barrier Properties?
PVDC's superior barrier capabilities stem from three key characteristics:
These features make PVDC a well-suited material for applications where high protection against oxygen and water vapor is essential.
The Role of Crystallization in Barrier Performance
PVDC's barrier properties are largely dependent on its degree of crystallization. To optimize these properties, processes such as stretching and aging are utilized to promote crystallization, thereby enhancing its effectiveness as a barrier.
PVDC Coating Techniques
PVDC is widely used for coating mono-films, co-extruded films and sheets. It is commonly applied to substrates such as OPP, PET, ONy, and PVC as a coating material, forming a transparent barrier layer. Two primary coating methods are used for PVDC:
Emulsion Coating
Utilizes a water-based PVDC Latex emulsion, offering safety benefits due to the absence of solvents and allowing for multiple coatings.
Solvent-Based Coating
This method uses organic solvents, producing thin, defect-free coatings ideal for specific applications.
For PVDC Latex applications, the emulsion method is predominantly used. PVDC particles coat the substrate during this process, achieving a densely packed arrangement. These particles then fuse together, forming a continuous film as the molecular chains interconnect.
Film Formation Process of PVDC Latex
This seamless barrier film provides robust protection against environmental factors, thanks to the fusion of particles and the diffusion of molecular chains.
Latex
What is PVDC Latex?
PVDC Latex is an aqueous emulsion produced through the emulsion polymerization of vinylidene chloride (VDC). When used as a coating, it provides high resistance to water vapor and oxygen, along with heat sealability, chemical resistance, and flame retardancy. It’s an excellent choice for enhancing the protective performance of films or paper used in packaging applications.
