Polypropylene is widely used across industries — and for good reason. Its exceptional versatility, outstanding durability, lightweight nature and low cost make it a very attractive material choice.

In the medical industry, polypropylene is safe for patients, nontoxic and doesn’t react to various chemicals, acids or bases. Its sterility and impermeability make it particularly well-suited for the lids and caps that cover containers including pill bottles, vials and fluid jars.

Another key attribute is its excellent high-temperature resistance, enabling the use of stainless steel seal heads for heat-sealing polypropylene lids onto containers. However, stainless steel seal heads come with notable limitations — friction, wear and progressive degradation over time — which can compromise sealing consistency and longevity. That’s why it’s important to protect them with a suitable coating.

One large medical manufacturing company contacted Magnaplate to solve a longstanding issue with the stainless steel seal heads it uses to seal polypropylene lids to bottles that contain various chemicals. Unfortunately, the customer’s polymer-based coating often failed after just 24 hours in the sealing process. This application presented multiple challenges that few coatings can effectively address all at once.

For example:

• Polypropylene, when heated, easily sticks to sealing equipment.
• Sealing temperatures can reach 470°F.
• The coating must be biocompatible, undergo sterilization and resist corrosion in a medical manufacturing environment.

We recommended Nedox® for the stainless steel seal heads. Nedox is an advanced electroless nickel coating infused with proprietary polymers to provide superior wear and friction protection plus excellent corrosion resistance and release properties up to 850°F. With Nedox, stick slip is eliminated and cleanup becomes fast and effortless. The composition is also FDA-compliant, making it particularly well-suited for pharmaceutical applications where residues often cling to metal parts. Nedox also performs exceptionally well in washdown-intensive environments.

Additional features and characteristics of Nedox include:

• Chemical, acid and alkaline resistance.
• Surface hardness to Rc68.
• Suitable for all types of metal parts.

Nedox Earns Customer’s Seal of Approval

Nedox has proven to be a superior replacement for the medical manufacturer’s prior polymer coating. It consistently withstands the intense heat and operational stresses of heat-sealing polypropylene lids onto containers. This successful application is another example of a Magnaplate surface treatment solving wear and stick-release problems.

When your application calls for surface treatment to eliminate wear and sticky material buildup, our specialists can suggest the right coating for your needs.

For more information, please visit our product page.