A comprehensive study on fluorination of HDPE container

It is widely known that the HDPE (High-density polyethylene) and PP (Polypropylene) is an ideal barrier for chemical packaging. And also perfect for making the drums and bottles with a property of flexibility, sealability, high impact strength, and functional stack load-bearing capacity.

The plastic is having a drawback against metal and glass, permeation and scalping is a problem. Many chemicals used to pack in HDPE and PP containers such as solvent, acid, lubes, oils, brake fluid, grease, flavors, fragrance, etc.  

Why do we need fluorination, is it stable with HDPE?

The HDPE drum barrier does not entirely support a few chemicals, and even we can’t go with metal and glass packaging. And therefore, we need a layer of fluorination required inside the drum to give surface modification. 

How fluorination reaction works:

Fluorination does a surface modification by substituting the hydrogen molecule with a fluorine molecule. There is no such change in the entire bulk properties of HDPE drums. The fluorination changes the HDPE polarity, cohesive energy, and surface tension. So this makes it has less wetting, dissolution, and diffusion of non-polar solvent relative to the polymer. 

The gas-phase fluorination of the HDPE container follows a two-step chemical reaction. The first step corresponds to one of the two hydrogen atoms’ spontaneous substitution on the carbon skeleton by a fluorine atom. The next step involves the substitution of the second hydrogen. These two steps occur during the induction period in a zone described as the “latent zone,” which is the boundary between the un-fluorinated and fluorinated polyethylene parts.

Full research article available on The Gas Phase Fluorination of High-Density Polyethylene http://epubs.surrey.ac.uk/851349/

How can we do the plastic fluorination process?

The plastic fluorination process placed inside a large metal container, loaded into a room, and then exposed to fluorine gas. This exposure generates carbon-fluorine bonding on the inside and outer bodies of the container. The bonding that occurs blocks the porous wall of plastic and helps to reduce and even eliminate the migration of aggressive chemicals.

There are several different levels of fluorination. Each level offers a different barrier level. Higher levels are used for more aggressive permeates and provide more barriers on the inside and outside surface areas.

Why fluorination required:

The fluorination is sufficient to decrease the permeability and reduce the paneling effect in the drum or also in bottles. 

• Protective against solvents that otherwise permeate through plastics

• Protecting containers and closures, resulting in superior product safety and integrity

• Stopping products from changing properties

• Meeting regularity standards for packaging many food products and providing safe use

• Retaining appealing odors and fragrances

• Stopping product loss

Not all kinds of plastic fluorination processes can take. For instance, PET containers cannot be fluorinated. You can select from opaque or transparent plastic, LDPE, HDPE, PP, PVC, and other plastics that can be fluorinated. The kind of plastic and the level of fluorination are essential and depend on the products you want to package.

Why Fluorine Gas for HDPE containers?

The carbon-fluorine bond is a polar covalent bond between carbon and fluorine that is a component of all organofluorine compounds. It is one of the most influential single bonds in organic chemistry—behind the B-F single bond, Si-F single bond, and the H-F single bond, and relatively short—due to its partial ionic character. The carbon-fluorine bond is organic chemistry’s most robust and gives stability to organofluorines. Molecules containing a carbon-fluorine bond often have very high chemical and thermal stability.

The fluorination process is resistant to most solvents and environmental stresses, making it an excellent choice for packing products susceptible to cracking.

The packaging material helps to preserve the food product by providing an oxygen barrier. This prevents the product from deteriorating and protects its stored container. The coating delivers prodigious barrier properties, which in turn permits the containers to be lighter. At some points, the container wall thickness was increased to avoid switching to multilayer because of cost. However, by applying Fluorination technology on HDPE / PP containers, we can reduce the thickness of the container wall in those cases and compensate by having a more prodigious barrier property.

The route suggests that legislation is forthcoming requiring ambitious recycling of packaging material. However, this is difficult because different layers of the material make it difficult to recycle. Fluorination technology makes it possible to recycle fluorinated products.

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