“Is there a UV-curable, medical-grade (safe to use in the body) biodegradable adhesive of any kind on the market right now? If not, would it be possible to formulate the adhesive?”
Dymax does not presently pursue implantable applications for our adhesives, and we are unaware of any adhesive on the market that would be biodegradable. Consequently, we cannot comment on the feasibility of such a product.
“Dymax curing equipment can be outfitted with several different types of bulbs. How do I choose the right bulb for my application?”
Metal halide bulbs (lamps) come standard in Dymax UV light-curing systems to match the cure chemistry of most high-performance UV-curable acrylate and cationic epoxy adhesives and coatings. Other bulbs offered include Mercury bulbs and visible indium bulbs. For curing UV inks and some (usually very thin layer) UV coatings, Mercury bulbs provide better surface cures faster. For applications where visible light is predominantly required for curing bonds between UV-blocking plastics, visible indium or “V” bulbs are best. The best approach to selecting a bulb is to speak with a Dymax Application Engineer. With a little information about your application, an Application Engineer will be able to select the most efficient bulb for your application.
“I want to find an epoxy that can bond two pieces of polycarbonate materials and be sterilized using autoclave. We tried using epoxy 353ND from Epoxy Technology but it is very difficult to cure completely, and after the sterilization process, the epoxy failed.”
Similar to light-curable adhesives, polycarbonate is usually not suitable for repeated autoclaving cycles. If a strong bond between the two pieces of polycarbonate is achieved, 1-5 cycles may be possible without damaging the adhesive and the polycarbonate.
There are several light-curable adhesives for polycarbonate available that are also approved for medical applications. One example is Dymax 1161-M, which I recommend for further testing with your application.
“Guidelines for Protecting Light-Sensitive Adhesives from Curing in Dispensing Equipment in Manufacturing Environments”
Unfortunately, manufacturing facilities that use standard fluorescent lighting sometimes have a problem with the polymerization of UV/Visible light-curable adhesives in dispenser tips and lines. The chemistry of these products make them extra sensitive to light, so extra measures must be taken to insure that unwanted polymerization does not occur.
To prevent this problem, manufacturers should shield needle tips and lines from light exposure. Incorporating lines that are black, opaque, polyethylene plastic will completely block light from the adhesive and eliminate the chances of unwanted polymerization. Dymax provides light-blocking materials for syringe needle tips. If these measures are insufficient and a process can’t be shielded through use of light-blocking materials, the fluorescent lamps in the facility could be retrofitted for existing incandescent and fluorescent fixtures.
Adhesives, Coatings, Dispensing Equipment
“We are observing a cracking problem in the bonding of a PVC tube and component of PC-144R with a 50% Cyclohexanone + 50% Tetrahydrofuran solvent mixture. Please suggest an alternative solvent for bonding the above component. Also describe why the polycarbonate is showing cracks when used with aforementioned solvents.”
There are cases where the PC tends to crack upon contact to attacking chemicals like ketones (Cyclohexanone, MEK) , ethers, and esters (Tetrahydrofuran):
- Applied stress due to joint design: when both parts are pushed into each other putting them into tension. To resolve, we recommend changing the design.
- Residual stress due to the molding process: when the molded PC does not cool down consistently. An annealing step (time and temperature to be determined) will relieve residual stress.
I would recommend looking at the possibility of stress within the Polycarbonate and make changes to design and/or process accordingly.
You can also look into switching to a light-curable adhesive, which is typically less harsh to Polycarbonate. For bonding PVC to PC, Dymax has a variety of products if you are interested exploring this path further.