“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.
“What bonding agent would you recommend for bonding soft PVC tubing to a polycarbonate connector? This is a sterile disposable tubing set.”
For this type of application I would recommend a light-curable adhesive. Dymax 1161-M could be a good candidate due to its ability to bond dissimilar substrates like PVC and polycarbonate together. This adhesive is solvent free, resistant to EtO, Gamma or Beta sterilization, and passes ISO 10993 biocompatibility testing. Via UV and visible light, the adhesive cures on demand within seconds using Dymax UV light-curing equipment.
“Can you suggest a medium-viscosity adhesive that is well suited for metal-to-metal bonding?”
“We are currently using Dymax 1184-M, M-B, and V for most applications. However, we’ve found out that they are not well suited for bonding metal to metal, partly because the cured hardness is too high and partly because the UV light cannot penetrate through metal seams.”
For metal-to-metal joints I would suggest looking at traditional epoxies rather than light-curable acrylates.
Epotec and Master Bond Inc. offer epoxies in medical-grade versions. There is an old article that describes the impact of Sterrad low-temperature hydrogen-peroxide-gas plasma on several adhesives. The article, along with the results, can be viewed at: http://www.mddionline.com/article/compatibility-medical-devices-and-materials-low-temperature-hydrogen-peroxide-gas-plasma.
According to the results in the article, some two-part epoxies from Epotec have a moderate compatibility with Sterrad.
“I understand DYMAX has a masking material that is biocompatible or had biocompatible testing done on it?”
DYMAX provides a selection of adhesives (http://www.dymax.com/products/medical/index.php) that have been tested according to ISO 10993 and are biocompatible in the cured stage.
A medical-grade material is typically not needed for temporary masking applications where the light-curable resin acts as a manufacturing aid only and is being removed before the end product is finalized.
“I have an application where I insert a 6 mm square shaft into a 6 mm + square hole to a depth of 6 mm. I need a product to bond these so the shaft does not pull out axially. There is very little force axially. Torque will be taken care of by the square. This is a veterinary medical instrument that does not stay in the body. Adhesive should be able to withstand 500-600 autoclavings and also be usable in ethylene oxide sterilization. “
To achieve a strong bond between two pieces of stainless steel and withstand 500-600 cycles of autoclaving, the best option would be a two-part or heat-curable epoxy. I would suggest trying Master Bond EP42HTMED, which is a two-component epoxy that cures at room temperature or via heat. Another supplier to contact is Epotec, who also offers medical-grade epoxies that will resist autoclaving and ETO sterilization.
"Is there a UV-curable adhesive that when cured conforms to USP Class VI and passes ISO 10993 requirements for permanent implant?"
Unfortunately, not that I am aware of. Technically, most light-curable adhesives are acrylated urethanes or epoxy-based systems, and would not survive permanent implantation. There are other hybrid light-curable technologies, but as far as I know none have been released technically for long-term implantation. In addition, the legal liability is too high for most applications. Perhaps something from the dental cement industry might be a suitable option.
"I have an application where the cuff is glued to the tube and I require a smooth, tapered transition between the cuff edge and the tube.
Writing will take place over this area; that is why I need the smooth, tapered glue connection."
It is very common to use an adhesive to make a nice, smooth, tapered transition between cuff edges and the tube, or marker bands, or transitions where there is a jump from one size tube to another. A low-viscosity adhesive in the 200-600 cP range, which cures rapidly to a smooth tack-free finish, is ideal. DYMAX light-curable materials like 1120-M-UR or 204-CTH-F are often used in these types of applications. Techniques include applying the adhesive in either a vertical or horizontal position, or even at a slight upward angle to achieve the taper. If it is a horizontal or tilted orientation, rotating the shaft during application and curing with a spot system for 1-8 seconds (typical), will allow the material to cure in the proper profile without risk of the adhesive slumping or running. Typically these transitions have a max height of 2-5 mils or less. Lower viscosities will have a sharper taper, and higher viscosities will have a shallower taper. Selecting the right needle dispense tip will help control adhesive quantity and position on the catheter shaft.
“I need a medical-grade adhesive to bond Ultem material to stainless steel (SS). This product will be a reusable medical product that will be autoclaved for 30 minutes @ 250° F”
To bond materials like Ultem and stainless steel, for a reusable device that will see autoclave conditions, the right choice in adhesives is important. As a general category, acrylates, urethanes, and cyanoacrylates will survive only limited autoclaving. Epoxies and silicones will have better success. Ultem is a difficult material, but with proper evaluation you might find a successful candidate. Silicone materials are available from companies like Dow Corning, Momentive, NuSil, and Wacker. Epoxy materials can be obtained from Epoxy Technology, Henkel/Loctite, and numerous others. Silicones will be softer and flex with the thermal stresses, while epoxies will be more rigid. It will ultimately depend on the part design and the number of autoclaving cycles the part will see.
A question that came through:
“What is the best adhesive for bonding a polyethylene terephthalate (PET) balloon to a polyether block amide (Pebax) substrate? What is the recommended surface preparation? Are other catheter-shaft substrate materials more suitable than Pebax for bonding to a PET balloon?”
Answer:
You should select a medium-flexibility light-curing adhesive with the viscosity to achieve the level of wetting and gap filling appropriate to your design. For example, DYMAX’s 204-CTH-F and 208-CTH adhesives have viscosities ranging from 155 to 500 cP. Such adhesives bond well to both PET and Pebax. In addition, it is important to choose an adhesive that fluoresces under a black light, enabling operators to detect and fix voids or air bubbles before the assembly is cured. This feature results in a better-quality bond and greater yields during production.
You can perform a surface treatment using plasma together with oxygen gas. While a plasma treatment with air gas—which has a lower O2 content than oxygen—is also effective, it is not as advantageous as using an oxygen plasma treatment. The oxygen deposits onto the surface of the material and increases the number of bond sites to which the adhesive can stick.
You ask whether other catheter-shaft substrate materials are more suitable than Pebax for bonding to a PET balloon. Pebax is commonly used for manufacturing catheter shafts because adhesives bond well to it. A polyether/nylon copolymer, the material can be mixed with higher proportions of nylon (polyamide) to create higher-durometer materials (72D), or it can be mixed with lower proportions of nylon to create lower-durometer materials (35D). The greater the amount of nylon in the Pebax, the farther apart are the bond sites and the more difficult it is to bond. For example, bonding PET to 35D Pebax is easier than bonding it to 72D Pebax. If you can incorporate a small layer of 35D Pebax at the bond location while retaining 72D Pebax underneath to achieve greater material stiffness, the bonding application will be improved.
A question that came through:
“We currently use one of your medical-grade adhesives with a viscosity of 500 cP. We are looking for a higher-viscosity adhesive and do not want to have to redo biocompatibility testing. Can you tell me if you have an adhesive that is made of the same materials as the one we now use but with a higher viscosity?”
Answer:
DYMAX offers adhesives with several viscosity variations. An adhesive might have a standard base viscosity of 500 cP but also be available in a T (thick) grade with a viscosity of approximately 5,000 cP, a VT (very thick) grade with a viscosity of approximately 12,500 cP, and a gel grade with a viscosity of approximately 25,000 cP. These thixotropic versions all use a nonreactive biocompatible thickener and exhibit the same biocompatibility test results as the standard product. The thixotropic adhesives with gel viscosity allow the material to have a little slump, a minor slump, or no slump at all, enabling them to be dispensed along a ridge or in a groove.
View our Viscosity Comparison Chart.