Simon Dearing, managing director of manufacturer Eurobond Adhesives, discusses some of the challenges medical devices present manufacturers with.
The challenge
Medical devices present manufacturers with a unique challenge. As well as being health-compatible, the materials used within these devices must allow high-precision production and permanent joining as well as withstanding various sterilisation methods. It is particularly important to consider all of these factors when choosing which adhesives to use for the assembly of medical devices.
Adhesives
Medical grade adhesives can be used to bond medical products such as syringes, dialysis filters, blood bags and tube connections. These medical products are usually made from a range of synthetic materials such as plastics that are hard to bond e.g. PolyEther Ether Ketone (PEEK), PolyEthylene (PE) and PolyPropylene (PP). On the other hand, common plastics such as PolyVinyl Chloride (PVC) and Acrylonitrile Butadiene Styrene (ABS) are well suited to bonding.
Disposable medical products
Disposable medical products are often produced in large quantities. It’s important for adhesives to possess mechanical bond strength, as well as being able to be rapidly cured. When adhesives have both of these properties high volume production can be ensured.
For transparent and UltraViolet (UV)-permeable materials, UV-curing medical grade adhesives can be used. For UV-impermeable substrates we recommend Light Emitting Diode (LED) curing, and for visual quality inspection, fluorescent versions of medical grade adhesives are also available. One such product is Vitralit UV 4802 which has been developed by German adhesives manufacturer Panacol and is supplied to UK businesses via Eurobond Adhesives.
Reusable medical products
For reusable medical products, durability and the ability to withstand frequent sterilisation play a vital role. Cured acrylate adhesives have a high resistance to sterilisation by autoclaving, gamma radiation and ethylene oxide. These sterilisation methods therefore have no measurable negative impact on Panacol's medical grade adhesives.
Additionally, electron-beam sterilisation has even been shown to improve the adhesion of some medical grade adhesives of the Vitralit series. This is thought to be due to an increase in the degree of polymerisation of these products.
Examples
Eurobond Adhesives supply USP class VI and ISO 10993 medical grade adhesives to manufacturers of medical disposable devices. These organisations use the adhesives Euorbond Adhesives supply to manufacture items such as catheter sets, syringe needle bonding, stop chocks, blood filter housings, bag/tube sets and many other disposable items.
Vitralit UV 4802 is a one-component acrylic system that cures very fast when exposed to light. Eurobond claim the system demonstrates excellent adhesion to many plastics such as PEEK, PolyEthylene Naphthalate (PEN) and Thermoplastic PolyUrethane (TPU). These plastics are all typically hard to bond with conventional adhesives. This adhesive also adheres very well to ceramics and glass. Tests have shown that the adhesive is highly resistant to heat and is able to keep its soft and flexible characteristics even after being exposed to temperatures of 150°C for seven days. As a result of its high flexibility the adhesive is perfectly suited for bonding thin and bendable PEEK plastic materials.
Vitralit UV 4802 is pink in colour and cures within seconds under a UV or visible light source. Both high pressure gas discharge lamps and LED curing systems are suitable for curing the adhesive. Once cured, the adhesive fluoresces which enables inspection of the bond line under black light.