Plastic Coextrusion & Its Uses – Explained

Posted on February 17, 2021

Where would we be today without coextrusion? There would be no multi-polymer tubing, which means the medical field could not function at the level it does today.

The process of custom tubes/coextrusions is not only imperative for medical areas such as cardiology but is an interesting subject when we look at the technology involved. The process is evolving and respected in its own right—we mustn’t take it for granted.

In the medical industry, plastic coextrusion are sometimes referred to as plastic sleeves. Find out more about them here.

what is plastic coextrusionWhat Is Plastic Coextrusion?

When two or more types of materials, such as polymers, are pressed through the same mold to produce a single piece, this is called coextrusion. It’s most popularly done with plastics and rubbers to create some important products we may take for granted today.

This process results in the pieces having properties unique to the original materials themselves, inside and out. This has been a great step forward in material engineering and we still have many more possibilities to explore within the field of manufacturing. The coextrusion machines will continue to evolve and give us ever more advances.

Coextrusion used to be a difficult task, but new technology, as it moves forward exponentially, is making it easier and less expensive. Plastic and rubber are the materials we’re going to cover in this article.

Let’s talk about some of the pieces we can make for use in the medical field. Then we’ll move on to some other products made by using this process.

medical field group of peoplePlastic Coextrusion In The Medical Field

Common items we make here at Petro Packaging with this process range from medical tubing to simply a sleeve that a more important device goes into for safe storage. The resulting products are also used for medical jobs where their part has to fit into a specific slot or medical device. Here are some examples of plastic coextrusion:

Catheters

One example of a coextruded medical supply is the catheter. A stripe of “radiopaque plastic” is extruded with the catheter material, which has the effect of helping x-ray quality as it moves through the vein. Adding this material doesn’t compromise its effectiveness, rather it improves it tremendously.

Multi-Lumen Tubing

Multi-lumen tubes have three or more separate holes that are constant down the entire tube. These are used when delivering oxygen, fluid, or wires. They can be created using any number of custom shapes, usually geometrical, with a round outer tube and are created using either custom or common thermoplastic resins.

Dual-Lumen Tubing

These are created in the same way as the above multi-lumen tubing but use interior shapes such as “D” shapes or circles, for example. These are commonly called “Double D” or “smiley face” tubes.

Profile Extrusions

These are similar to dual-lumen tubing except the outside of the tube will be non-round. These can be manufactured using custom outer profile shapes inside a coextrusion machine.

Monofilaments

These are round, solid extrusions of custom nylon or thermoplastic polymers. They’re used in assessing the sensations in peripheral nerves, especially in patients with neuropathic conditions such as diabetes mellitus.

In the foot, for example, if they can’t feel the prodding of such a monofilament, that will usually mean a diabetic peripheral neuropathy diagnosis.

Striped Tubing

Adding a colored stripe to a tube can help denote which chemical or substance is being passed through it during a medical procedure. You can see how important this can be. The colors are added to the tubes much like they’re added to drinking straws, for example.

Paratubing

This sounds like a watersport, but it’s actually a technique is used to attach two tubes with a thin web of plastic. They’re also called “peel-apart” tubing. They are bonded along the entire length but can be separated at any point(s).

What Materials Are Used?

These amazing materials have endless possibilities, some block UV rays while some are anti-microbial. Here’s a list of materials that are commonly used in coextrusion:

  • ABS
  • PETG
  • CAP
  • PVC
  • Polyurethane
  • Polypropylene
  • Polystyrene
  • HDPE & UHMW Polyethylene
  • Acrylic
  • TPR/TPE/TPV
  • Nylon
  • PTFE
  • Polycarbonate

Two or more of these materials can be coextruded in striped alignment or blended. They can cover the outer or inner surfaces of tubing or help in the construction of medical devices. They have uses in the pharmaceutical industry as well.

drinking strawsOther Popular Uses

Coextrusion is in your everyday life and you may not know it. Fences and Handrails can be constructed using recycled plastics, reground scrap, and virgin material.

This is used to create food and cosmetic containers as well. Often the result is stronger than the original material and reduces costs, so it’s a win-win.

As we mentioned above, your average plastic drinking straw is a product of the striping of plastic using a plastic coextrusion machine.

PVC pipes, plastic bags, packaging, and plastic insulated wires can all be made using various methods of coextrusion if two or more polymers are needed. The methods include sheet extrusion, blown film, and tubing extrusion.

Sheet Extrusion

This is done with plastic film coextrusion by first running a thick sheet of plastic through a die. This changes its consistency. Afterward, it’s ready to be transformed into packaging, for example. To do this it’s thermoformed (heated and molded) into the required shape.

Blown Film

We use this method to make plastic bags. It involves running material through a die and directing it around certain open or interior spaces. Then it’s cooled, stretched with rollers and air pressure.

Tubing Extrusion

This is a lot like the blown film process, except tubing extrusion results in thicker, stronger plastic products that are hollow. PVC and other types of pipes or hardware are made using plastic coextrusion machines.

Coextrusion Is Here to Stay

We’ve discussed the processes and products, and discovered the secrets behind the creation of everyday products. Who knew plastic coextrusion involved so many different polymers and careful chemistry?

When choosing a company for your coextrusion products or machines, especially for the medical field, you must be diligent and careful. These are parts of devices and products that need to be precisely made in order to work properly and safely.

Don’t compromise the integrity of your products. Contact us today with any questions!