Summary: As the world moves ever closer to a truly circular economy, manufacturers are under pressure to turn plastic waste into functional materials. But there are process challenges that come with doing so. Specialty oxidized waxes are capable of meeting some of those challenges.
Over the last decade, the circular economy has evolved from a technical theory to an industrial reality. Participation has become a necessity as manufacturers face growing pressure to incorporate post-consumer recycled (PCR) and bio-based materials into their supply chains. But the challenges of doing so are many and varied. One of the biggest is the reality that recycled materials do not behave the same way as their virgin counterparts.
Overcoming differences in behavior often boils down to the materials used in processing. Specialty waxes, and oxidized waxes more specifically, represent an advanced solution in chemical engineering capable of bridging the gap between material performance and sustainability.
While most manufacturers are familiar with standard paraffin or polyethylene waxes, many are just learning about specialty oxidized waxes. The more they learn, the more oxidized wax becomes the go-to solution for integrating more sustainable resins and other raw materials.
Oxidized Wax: The Basics
Oxidized waxes begin as traditional synthetic waxes, like high-density polyethylene (HDPE). These synthetic waxes are manipulated through oxidation. By introducing oxygen groups – typically carboxylic acids and esters – to the polymer chain, we gain wax polarity. This is an enormous change in terms of how the waxes will interact with other materials.
Standard synthetic waxes are nonpolar. They do not interact well with anything other than simple plastics. But oxidized waxes more easily accommodate polar surfaces, including metals and pigments. More importantly, the waxes interact well with the degraded functional groups typical of recycled plastics.
Why It Makes a Difference
The ability of an oxidized wax to properly interact with recycled plastics is a game changer for the circular economy. If you are not sure why, consider one of the biggest problems that comes with integrating recycled polymers: every time a plastic is reheated and extruded, some of its polymer chains break down, leading to inconsistent melt flow and degraded mechanical properties.
Oxidized waxes address this challenge in two ways:
- Lubrication – Oxidized waxes can be deployed as high-efficiency lubricants that reduce the viscosity of the polymer melt. This allows recycled resins to flow freely even at lower temperatures and pressures.
- Consistency – Oxidized waxes also improve the consistency of finished surfaces. This is accomplished through better contaminant dispersion that reduces service imperfections and creates finishes that rival virgin plastic.
Oxidized waxes can also be used as a bridge between dissimilar materials, something that is important to circular design. If you are trying to combine materials like biopolymers and traditional polyolefins, they may not adhere well. An oxidized wax changes the game.
Oxidation creates a wax with both polar and nonpolar ends. It acts as a coupling agent that holds dissimilar materials together. It stabilizes the interface to prevent delamination and improve structural integrity. The final product is as good as one made with virgin materials even though it contains a significant amount of recycled material.
3 Practical Applications in Circular Manufacturing
In theory, it is easy to explain how oxidized waxes benefit the circular economy by allowing manufacturers to use more recycled material. But what does that look like practically? How do oxidized waxes work on the factory floor? Below are three practical applications:
1. PVC Recycling
PVC is one of the most commonly utilized plastics in the world. It can be recycled, but it is heat-sensitive. Oxidized polyethylene wax is essential to overcoming this particular problem when recycling PVC pipes, windows, and waste.
Oxidized waxes prevent hot melt from sticking to the metal surfaces of the extrusion environment. In addition, introducing oxidized wax at the precise moment PVC powder becomes a molten mass prevents thermal degradation.
2. Water-Based Coatings and Adhesives
Traditionally, the coatings and adhesives used for packaging purposes have contained volatile organic compounds (VOCs) we are now trying to get away from. Indeed, the circular economy demands that VOCs be avoided whenever possible.
Fortunately, oxidized waxes can be emulsified into water. The resulting materials are then used in recyclable paper packaging to provide both moisture and slip resistance. Packaging doesn’t absorb water, and individual packages do not stick together during shipping and handling. At the same time, the repulpibility of the paper is not compromised.
3. Pigment Dispersion
One of the downsides of recycled resins is the well-known gray or yellow tint resulting from repeated heat cycles. Manufacturers must introduce heavy pigment loads to overcome the poor color. Synthetic waxes are introduced to wet these pigments. Those with high oxidation levels do a better job of wetting, guaranteeing that the color of the finished product is both vibrant and uniform.
Synthetic oxidized waxes do an exceptional job of pigment dispersion even when the base material is primarily PCR. Despite the material’s inconsistencies, oxidized waxes get the job done.
Making Waste Functional Again
On a broad scale, the circular economy is not just about reducing waste. It is also about taking waste materials and putting them back into manufacturing. It’s about making waste functional again. But adding function back into degraded materials is more easily said than done. It takes specialized knowledge and more advanced techniques and tools.
Oxidized waxes are ideal for helping turn plastic waste into reusable material. They are the intermediary between degraded, recycled feedstocks and high-performance, marketable goods. They are exactly what your processes need if you are struggling with melt fractures, inadequate adhesion, or poor dispersion.
Don’t try to overcome your manufacturing challenges by throwing more plastic into the problem. Instead, look at oxidized waxes and what they bring to the table. We can probably help with specialty wax uniquely tailored to your process needs.
Trecora specializes in high-precision synthetic wax manufacturing. Each of our synthetic waxes is tailored for a unique and demanding environment. We encourage you to take a look at our specialty portfolio to learn more about how oxidized wax helps manufacturers increase their PCR content without sacrificing the structural integrity, mechanical durability, or aesthetic appeal of their finished products.
FAQs
What is the biggest difference between a traditional synthetic wax and an oxidized wax?
In a word, polarity. Standard synthetic waxes are nonpolar while oxidized waxes are polar.
Are oxidized waxes better than standard waxes for working with recycled plastics?
Recycled plastics tend to contain polar impurities as a result of previous heat cycles. Where standard waxes may separate, oxidized waxes hold together the inconsistent chains of a PCR resin. So yes, they are better.
Do oxidized waxes impact future recyclability?
Not only do oxidized waxes not harm future recyclability, but they also often improve it. By their nature, oxidized waxes are not contaminants. They also improve structural integrity, allowing plastics to be recycled multiple times.
Can oxidized waxes improve melt release?
Yes. The polar groups in an oxidized wax form a microscopic protective layer that overcomes the tacky nature of recycled melt.
Can oxidized waxes be deployed when manufacturing food-contact packaging?
As long as an oxidized wax is manufactured according to FDA and other pertinent regulations, yes. However, acid value must align with packaging application.
