The medical device industry has a wide range of products and applications that are a fit for medical molding, and choosing the right material from the beginning will save significant time and resources.
Often, it’s easy to be confused about which “soft material” you should choose for your application when there are so many options, especially when comparing TPE to LSR. The first place to start in your medical application is with the environmental conditions of the application, which can help narrow down the choices.
TPE: A great choice for a variety of medical device applications and some implantable devices, cost effective process, recyclable during the molding process, and has a high range of “softness”.
LSR: With high chemical and heat resistant properties as well as less diverse reactions to skin contact, this material is ideal for implantable device applications.
TPE Basics
TPE stands for Thermoplastic Elastomer and, in general, is a flexible material that can be stretched repeatedly to over twice its length with a range of softness on a durometer scale. The most common general application for TPE is to “over-mold” it onto a substrate for a “soft touch” feel. Typically, TPE’s are most commonly used on handles or areas that would be physically touched.
Traditionally, there were 6 primary TPE types categorized into two generic classes,
However, over the past few years, there have been two additional emerging technologies;
A major benefit of TPE over LSR is its recyclability. This allows a “re-molding” opportunity with the TPE without chemically changing the material; this differentiator, as well as a less expensive molding process vs LSR, will, in turn, typically result in lower production costs.
According to medicalplasticsnews.com, “Medical device manufacturers increasingly turn to thermoplastic elastomers (TPEs) for applications that require flexibility or rubber-like elasticity. These compounds have replaced alternative materials such as thermoset rubber and PVC in standard applications, including tubing, bags, pouches, drip chambers, masks, cushions, syringe tips, ventilator bags, luers, stoppers, gaskets, seals, and dropper bulbs.
And as designers have come to appreciate the value of TPEs, more and more are using these elastomers for new applications.
TPE growth in medical devices involves their advantages over alternative materials. The most obvious advantages stem from the fact that TPEs are thermoplastics. They process more efficiently and economically than thermoset rubber, provide greater design freedom, exhibit a wider range of color options, and, unlike rubber, can be recycled.
At the same time, TPEs provide device manufacturers with a means of obtaining comparable or even superior properties while avoiding problems associated with certain alternative materials.
LSR stands for Liquid Silicone Rubber and is typically either injection molded or compression molded. LSR is a thermosetting polymer, which means that once it’s molded, it cannot be recycled like the thermoplastic counterpart in TPE. The main raw material is sand, or silicon dioxide, which is then combined with methyl chloride to create different types of silicone, including liquid silicone rubber.
Much different than TPE, LSR uses a two-component reactive chemical that is mixed, heated up, and then changed into a rubber form. Because the LSR components are shipped in sealed containers and processed with a closed system, there are fewer issues with dust and moisture contaminants.
In medical molding, LSR usage has been increasing over the years for implantable devices, mainly because during the molding process, it cures completely. This means that the device will not leach chemicals and potentially cause adverse reactions in the patient. Since LSR has an extremely high heat and chemical resistance, it can handle rigorous sterilization processes, which make it a good fit for many different applications in the medical industry.
Due to the key differences between thermoplastic elastomers (TPE) and thermosets (LSR), choosing the right supplier for your application can be difficult, depending on how many implantable vs non-implantable products your company produces. Often, the molding supplier will focus on either thermoplastic or thermoset materials for the majority of their business, with some companies having a few machines/processes for their non-dominant material.
If your company mainly produces non-implantable products, then it’s a good idea to focus on a TPE molding expert who has all of the certifications and cleanroom facilities to handle most of your product needs. This, in turn, means that any implantable products ideal for an LSR application should be sourced from a company that focuses primarily on LSR molding.
Crescent Industries has been providing TPE and thermoplastic solutions to the medical industry for over 60 years. Our application expertise spans a wide range of uses in the medical, dental, and pharma industries, leveraging ISO 13485 certification and Class 7 clean room operations, providing assembly and packaging services. Crescent continues to expand its technology and is dedicated to providing the medical, dental, and pharma industries with the highest-quality products that solve some of the most challenging applications.
Contact us today to learn how Crescent can assist with your injection molding project!