Medical Elastomers And Latex

Why TPES (Thermoplastic Elastomers) can replace Thermoset rubbers in medical applications?

Mr. Manan Shah, Rubber Technologist

Thermoset rubbers are used in all medical applications of rubber technology.

Rubber expenditures often rank at or near the top of material costs in medical companies, because of the need for elastomeric components in most medical products.

Factors driving move to replace thermoset rubbers with TPEs :

1. Processibility and design flexibility of TPEs
2. Cleanliness of TPEs (Low extractables)
3. Material Cost

Any one or a combination of these three factors can lead to an overall cost reduction for the product or to a marketplace advantage over traditional thermoset products.

1. Processing of TPEs :

As TPEs are thermoplastic, they can be processed on any type of equipment that can hand thermoplastic materials including standard thermoplastic injection molding machines and extrusion equipment.

While thermoset rubbers require special vulcanizing equipment and cannot be handled by personnel familiar only with thermoplastic engineering technology.

So, Medical products manufacturers’ generally buy thermoset rubber parts from outside vendors which implies loss of manufacturing and cost control.

The ease of TPE processing using conventional thermoplastic equipment gives medical product manufacturers the opportunity to fabricate parts in-house on their own equipment.

The medical product producer can have following advantages of thermoplastic processing over thermoset plastic technology :

The above processing advantages result in lower overall manufacturing costs and better quality control of the final product.

Thermoset Rubber Fabrication involves numerous control and processing steps which are not required in TPEs’ fabrication scheme.

Every steps in a medical manufacturing environment would have to be monitored, adding to cost of the thermoset manufacturing process.

2. Cleanliness of TPEs versus Thermosets :

• Numerous chemical additives, vulcanizates, and fillers must be added to gum rubber matrices for the purpose of crosslinking the rubber and/or providing the necessary engineering properties to the thermoset rubber. These catalysts and processing aids give rise to a major problem often encountered in biomedical applications of thermoset rubbers.
  
  Therefore, washing steps are normally used by the medical industry to remove/extract surface residuals from thermoset rubbers, thus reducing the toxicity of these materials to acceptable levels. Such cleaning and extraction processes add a substantial cost to the rubber part.

• The cleanliness of thermoplastic elastomers, from the standpoint of toxicity and extractables, often makes them superior materials for use in medical products.

• It is not necessary to wash TPE parts after fabrication as they generally will pass the required toxicity tests.

• Many variability associated with thermoset materials is virtually eliminated with TPEs.

So, above lack of overall elutables from TPEs, coupled with ease of processing, that makes this new family of melt processible elastomers of major interest to medical community.

Potential replacement of thermoset rubbers by TPEs in medical products

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