As a supplier of Polyvinylidene Chloride (PVDC) Plain Film, I’ve received numerous inquiries about flame retardant additives for this product. Flame resistance is a crucial feature in many applications where PVDC plain film is used, such as in packaging materials for electronics, food products that need to be stored in high – risk areas, and in some construction and industrial settings. In this blog, I’ll delve into the various flame retardant additives suitable for PVDC plain film. Polyvinylidene Chloride Plain Film
1. Halogen – based Flame Retardants
Brominated Flame Retardants
Brominated flame retardants have been widely used in polymers, including PVDC plain film, for decades. Their effectiveness lies in their ability to interrupt the free – radical chain reaction that occurs during combustion. When the film is exposed to heat, the brominated compounds decompose and release bromine radicals. These radicals react with the flammable hydrogen radicals that are generated during the combustion process of the polymer. By doing so, they reduce the concentration of hydrogen radicals and slow down or even stop the combustion reaction.
Some common brominated flame retardants used in PVDC plain film are decabromodiphenyl ether (deca – BDE) and tetrabromobisphenol A (TBBPA). Deca – BDE has high thermal stability, which is beneficial as PVDC plain film may be exposed to elevated temperatures during processing and use. TBBPA, on the other hand, can also be copolymerized with the polymer matrix, providing a more integrated flame – retardant effect.
However, the use of brominated flame retardants has faced some environmental and health concerns. They are persistent in the environment, and some studies have shown potential negative impacts on human health, such as endocrine disruption. Therefore, in recent years, there has been a push towards more environmentally friendly alternatives.
Chlorinated Flame Retardants
Chlorinated flame retardants are also an option for PVDC plain film. Since PVDC already contains chlorine in its structure, chlorinated flame retardants can have good compatibility with the polymer. They work in a similar way to brominated flame retardants, by releasing chlorine radicals during combustion to interrupt the free – radical chain reaction.
One example is chlorinated paraffins. Short – chain chlorinated paraffins (SCCPs) were once commonly used but have been restricted due to their persistence, bioaccumulation, and toxicity. Medium – chain and long – chain chlorinated paraffins are still used in some applications, with the long – chain ones being considered relatively less harmful.
2. Phosphorus – based Flame Retardants
Inorganic Phosphorus Flame Retardants
Inorganic phosphorus – based flame retardants such as ammonium polyphosphate (APP) are popular choices for PVDC plain film. APP works mainly through a char – forming mechanism. When heated, APP decomposes to form phosphoric acid, which then promotes the dehydration of the polymer. This dehydration leads to the formation of a char layer on the surface of the film. The char layer acts as a physical barrier, preventing oxygen from reaching the underlying polymer and also reducing the heat transfer.
APP has several advantages. It is relatively non – toxic and has good thermal stability. It can be used in combination with other flame retardants to enhance the overall flame – retardant performance. In PVDC plain film, it can be incorporated at various loadings depending on the required level of flame resistance.
Organic Phosphorus Flame Retardants
Organic phosphorus flame retardants offer a different set of properties compared to inorganic ones. For example, tris(2 – chloroethyl) phosphate (TCEP) and resorcinol bis(diphenyl phosphate) (RDP) are commonly used. TCEP is a well – known flame retardant that can be easily mixed with PVDC during the film – making process. It has good solubility in some solvents and can be evenly distributed in the polymer matrix.
RDP, on the other hand, has high thermal stability and good hydrolytic stability. It can improve not only the flame resistance but also the mechanical properties of the PVDC plain film to some extent. These organic phosphorus flame retardants can be used alone or in combination with other additives to achieve the desired flame – retardant and physical properties.
3. Metal Hydroxides
Aluminium Hydroxide
Aluminium hydroxide (ATH) is a widely used flame retardant in many polymer applications, including PVDC plain film. It acts through an endothermic decomposition reaction. When heated, ATH decomposes to form aluminium oxide and water vapor. The endothermic nature of this reaction absorbs heat from the surrounding environment, thereby reducing the temperature at the surface of the film and slowing down the combustion process.
The water vapor released during the decomposition also dilutes the concentration of flammable gases near the surface of the film. ATH is non – toxic and has good smoke – suppressing properties. However, it usually needs to be added at relatively high loadings (up to 60% in some cases) to achieve effective flame retardancy, which can have an impact on the mechanical and optical properties of the PVDC plain film.
Magnesium Hydroxide
Magnesium hydroxide (MDH) functions in a similar way to ATH. It decomposes endothermically at a higher temperature than ATH, which gives it an advantage in applications where the film may be exposed to higher heat. MDH also releases water vapor during decomposition, diluting the flammable gases.
Compared to ATH, MDH can be used at lower loadings in some cases to achieve similar flame – retardant effects. It also has a positive impact on the smoke – suppression performance of the PVDC plain film. However, like ATH, high loadings of MDH can affect the physical properties of the film, such as its flexibility and transparency.
4. Synergistic Combinations
Often, using a single flame retardant additive may not be sufficient to meet the strict flame – retardant requirements in some applications. Therefore, synergistic combinations of different flame retardants are commonly employed. For example, a combination of a halogen – based flame retardant and a metal hydroxide can provide enhanced flame – retardant performance.
The halogen – based flame retardant can act quickly to interrupt the free – radical chain reaction at the initial stage of combustion, while the metal hydroxide can absorb heat and release water vapor to further suppress the fire. Another common combination is between a phosphorus – based flame retardant and a halogen – based one. The phosphorus – based flame retardant can promote char formation, and the halogen – based flame retardant can work on the gas – phase combustion.
Choosing the Right Flame Retardant Additive
Selecting the appropriate flame retardant additive for PVDC plain film depends on several factors. Firstly, the specific application requirements play a crucial role. For example, if the film is used in food packaging, the additive must be non – toxic and comply with food – contact regulations. If it is used in electronics packaging, the additive should not interfere with the electrical properties of the packaged components.
Secondly, the processing conditions of the PVDC plain film need to be considered. Some flame retardants may have poor thermal stability and can decompose during the high – temperature processing of the film, leading to a loss of flame – retardant effectiveness.
Finally, cost is also an important factor. Different flame retardants have different costs, and the choice should be made based on a balance between performance and cost.
As a supplier of PVDC plain film, I understand the complexity of choosing the right flame retardant additive. We have a team of experts who can provide technical support and guidance to our customers. Whether you need a highly flame – resistant film for a specific industrial application or a safe and compliant film for food packaging, we can help you select the most suitable flame retardant additive and produce the high – quality PVDC plain film that meets your needs.
Coextruded Film If you are interested in our PVDC plain film products or need more information about flame retardant additives, please feel free to contact us for procurement discussions. We are committed to providing you with the best solutions and products.
References
- ASTM International. Standard Test Methods for Flame Retardancy of Plastics.
- Grisoni, M., & Camino, G. (Eds.). (2012). Flame Retardancy of Polymers: New Strategies and Opportunities. Springer.
- Weil, E. D., & Levchik, S. V. (Eds.). (2008). Flame Retardants for Plastics and Textiles: Practical Applications. Hanser Gardner Publications.
Sinosealed Packaging Solutions Limited
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