Needle Bonding

A main field of application for adhesives in medical systems is needle bonding and syringe assembly – the bonding of stainless steel needles or cannulas into glass or plastic syringes. The needles’ required high withdrawal forces are achieved through precision manufacture (needle position, adhesive dosing and reliable adhesive curing), choice of hub (material and design) and, in particular, the right adhesive system.

Already the hub material used affects the choice of adhesive, since not all adhesives adhere well to all plastics. Many adhesives are UV-curing, which requires the use of transparent and UV-permeable materials. For materials that block UV light, such as polycarbonates, long-wave LED curing is recommended. All needle bonding adhesives listed in the table below can be LED-cured.

The hub design also plays an important role for the assembly of syringes: it determines whether a mobile adhesive that flows into the needle hub through capillary action or a highly viscous adhesive capable of filling large gaps is used. In some cases the needle shaft must be designed with grooves to provide an additional key for the adhesive.

Panacol offers various adhesives that are suitable for bonding stainless steel needles into glass syringes and stainless steel cannulas into syringes made from plastics such as PC, PVC, PP or ABS. All adhesives recommended for needle bonding are solvent-free and certified USP Class IV and/or ISO 10993 for use in medical equipment. In addition, high needle extraction forces were measured with all needle bonding adhesives even after several sterilization cycles. Electron-beam sterilization has even been shown to improve the adhesion of some adhesives of the Vitralit® series.

All adhesives are also available in fluorescent versions, which allows a fast and efficient quality control during production.
 

Needle bonding: A needle is being bonded into a syringe; the adhesive is cured with two LED heads

The table below lists a selection of needle bonding adhesives from Panacol. Further products and custom solutions for needle assembly are available on request. 

Adhesive/ Needle Bonder Application Viscosity [mPas] Base Curing* Properties
Vitralit® 6108 glass bonding
medical technology
potting material
600-900 acrylate UV
VIS
thermal
Non-yellowing
excellent flow properties
certified to USP Class VI and ISO 10933-5 standards
Vitralit® 6108 T glass bonding
medical technology
potting material
4,000-6,000 acrylate UV
VIS
thermal
Non-yellowing
excellent gap-filling
certified to USP Class VI standards
Vitralit® 7041 medical technology 50-90 acrylate UV
VIS
Excellent adhesion to glass, plastics and metals;
certified to USP Class VI/ ISO 10993/-4/-5 standards
Vitralit® 7041 T medical technology shear thinning acrylate UV
VIS
Excellent adhesion to glass, plastics and metals;
certified to USP Class VI/ISO 10993/ -4/-5 standards;
high viscosity/stable
Vitralit® UV 4050 medical technology
plastic bonding
140-500 acrylate UV
VIS
Certified to ISO 10993-5 standards
modified acrylate
impact resistant
very fast curing
very high adhesion to plastics
Structalit® 5893 glob top encapsulation
SMD assembly
medical technology
needle bonding
6,000-10,000 epoxy thermal Black color
excellent flow properties
filling material
high resistance to heat and chemicals
certified to ISO 10993-5 standards

*UV = 320 - 390 nm          VIS = 405 nm