Thermoplastics for injection moulding medical components

Thermoplastics for injection moulding medical components

The global medical plastics market is set to grow by 7.2% to $76.7 billion by 2031 according to a recent report by Transparency Market Research (TMR). The report highlights that growth is largely driven by the use of plastic devices such as syringes, catheters and patient diagnostic equipment. However, other equipment, implants and medical products that come into direct contact with patients are also influencing growth. The same can be said for plastic housings for automated medical equipment and even clips, fastenings and connectors used for hanging products such as medical curtains or surgical equipment.

6 reasons polymers are used in the healthcare market:

  • Cost effective – yet offer high performance properties.
  • Lightweight – compared with metals, composites, ceramics, or glass.
  • Widely available – in a large range of polymer types for different applications.
  • Medically approved – a large number of existing medical grade polymers
  • Easy to process – through injection moulding but also secondary processing such as EMC coating, adhesive bonding, welding – hot plate, laser transmission, spin and ultrasonic – plus heat staking to name a few.
  • Very versatile – you can colour them and change the properties to make them conductive or anti-microbial as required.

One of our earlier blogs covers the advantages of plastic injection moulding for medical devices, here we take a closer look at the types of plastic that can be used.

Types of medical grade polymer:

Commodity Polymers – such as PP, PE and ABS. Low cost and readily available, make these the first port of call. Many of these grades are ISO 10993 compliant for Biocompatibility.

Examples of Commodity Polymers:
  • Polyvinyl Chloride (PVC)
  • Polypropylene (PP)
  • Polyethylene (PE)
  • Polystyrene (PS)
  • Acrylonitrile Butadiene Styrene (ABS)

Engineering Polymers – such as Copolyester, PBT and PET, PC, PC-ABS, Nylon and PPO. These are more expensive than commodity polymers, but provide improved thermal properties, electrical, wear and solvent resistance. Most have a higher melting point and require more expertise and knowledge for processing.

Examples of Engineering Polymers:

  • Copolyester
  • Polybutylene Terephthalate (PBT)
  • Polyethylene Terephthalate (PET)
  • Polyamide (Nylon)
  • Polyoxymethylene (POM or acetal)
  • Polycarbonate (PC)
  • Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS)

High Performance Polymers – such as polyketones, polysulfones (PPSU), polyarylates, polyamides, and liquid crystal polymers (LCP) such as PEEK. Characterised by a combination of high modulus, melting points (greater than 250°C), biocompatibility, electrical insulation, and low-friction surfaces.

Examples of High-Performance Polymers:

  • Polysulphone (PPSU)
  • Polyether ether ether ketone (PEEK)
Example of PPSU - Thermoplastics for injection moulding medical components

In addition to the Thermoplastic polymers listed, there is also a wide range of Thermoplastic Elastomers (TPE) and Thermoplastic Urethanes (TPU) as well as more exotic materials such as PCU (Polycarbonate Urethane) which passes USP XXII Class VI Biological Reaction. These are generally soft, rubber compounds, used for seals, cushioning features and soft touch surfaces. These materials can be moulded in on their own as components or bonded to polymers with matching chemistry, for a chemical bond, as opposed to a mechanical bond using either overmoulding or 2-shot moulding technology.

6 considerations for choosing a material for your medical device

  • Part functionality and therefore its performance requirements, such as:
    – mechanical
    – thermal
    – electrical
    – sterilisation method
    – biological and chemical resistance to cleaning agents
  • Manufacturing volumes – low, medium or high annual volumes (for example you may choose a ‘nucleating agent’ to improve the rate of polymer crystallisation for higher manufacturing volumes
  • The environment your device or part will be used in – is it in contact with the body? Is it going inside the body? Is it a piece of diagnostic equipment for non-contact monitoring?
  • Regulatory requirements
  • Material price
  • Material availability

In our next blog we will focus in more detail on the commodity materials used to manufacture parts for medical devices. We will highlight the properties of each thermoplastic, explaining why it is used for plastic injection moulding particular components and the types of medical applications it is suited to.

If you need advice in selecting a material for your next medical device project, our expert team at OGM is always happy to help. We manufacture to medical standard ISO 13485 and have an ISO 7/ Class 10,000 cleanroom. Contact us for more information.

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