“We have recently taken on some medical tubing device-assembly work from another company but the information supplied seems to be missing some crucial points. We are having bond-strength issues when fixing a flexible PVC tube into the female port of an ABS connector.

The instruction we had was to use 100% cyclohexanone, but my feeling and internet research seems to show some form of cyclo/THF and pellet combination would perform better. Would you agree or is there a ready-made alternative available?”

In general, adding pellets (PVC) to the solvent mixture can help avoiding stress cracks and allows more flexibility in the gap design due to its gap-filling properties. So far, we have not come across a readily available mixture.

If you consider moving away from using solvent, I would suggest looking at light-curable adhesives. Dymax offers a variety of products suitable for bonding PVC to ABS. Medical grade adhesive Dymax 1161-M for instance provides strong bonds to a variety of substrates and cures within seconds upon exposure to UV and/or visible light.

Adhesives, Medical bond ABS to PVC, bond PVC, bond tubing, Light Curable Adhesive, light-curable adhesives, Medical-Grade Adhesive, PVC Tubing, solvent bonding

“We are looking for a medical-grade adhesive for bonding PEBAX (72D MED) tubing to latex nature rubber. We need shore hardness of a UV adhesive below 50D after cured. What is the best adhesive for this application? Also, which pre-surface treatment is suitable for PEBAX?

We also need a medical-grade adhesive for bonding PEBAX (72D MED) tubing to a colored ABS hub. Which fast setting adhesive is suitable for this?”

Latex nature rubber can typically be bonded with cyanoacrylates, also referred to as Super Glue. The Dymax medical grade 222 series cyanoacrylates might be a good place to start.

For bonding PEBAX I would suggest looking at Dymax 208-CTH-F, which is a medical grade, light-curable adhesive with shore D55. To combine PEBAX with latex or colored ABS, light-curable adhesives might not be suitable due to low adhesion to latex and problems with light curing through the colored ABS hub. Therefore, a cyanoacrylate is most likely the adhesive of choice.

Adhesives, Cyanoacrylates, Medical ABS to Pebax, bond Latex, bond Pebax, bond PEBAX to Latex, Cyanoacrylates, Medical-Grade Adhesive, Pebax, Plastic Bonding

“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.

Adhesives, Medical biodegradable adhesives, Light Curable Adhesive, light-curable adhesives, Medical-Grade, Medical-Grade Adhesive, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“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.

Adhesives, Medical autoclave-resistant adhesive, bond PC, bond polycarbonate, epoxy, plastic bonder, Plastic Bonding

“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.

Adhesives, Medical 1161-M, bond PC, bonding PVC, gamma sterilization, Light Curable Adhesive, light-curable adhesives, Medical-Grade, Medical-Grade Adhesive, Plastic Bonding, PVC Tubing, tubeset bonding

“We are looking for a good adhesive to pot Nitinol or Titanium wire into a hole in a Noryl device. The hole is 0.156″, while the wire is 0.125″. We are looking for an adhesive that can stand up to re-sterilization using various methods of sterilization including autoclave and EtO, and that will also fill the gaps well. Can you recommend an adhesive?”

If the number of sterilization cycles is limited to a few you may be able to utilize a light-curable adhesive for your application. Dymax 1128A-M is a medical-grade adhesive that cures with UV and visible light, and exhibits good adhesion to a variety of metals. Adhesion to the Noryl will have to be tested.

If more than 10 cycles of autoclave sterilization are required then the best choice of adhesive will be either a heat-curable or two-part epoxy. Masterbond and Epotec offers a variety of materials that are medical grade and suitable for repeatable sterilization.

Adhesives, Medical 1128A-M, medical grade adhesives, metal bonding, nitinol bonding, noryl bonding

“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.

Adhesives, Medical 1184-M Series, Light Curable Adhesive, light-curable adhesives, medical adhesives, medical device adhesives, Medical-Grade, Medical-Grade Adhesive, metal bonding, metal to metal bonding

“I would like to know the best adhesive to use in our cannula and metal-wire bonding processes. The details are as follows:

3. Nitinol wire to ABS/PC - need thicker adhesive for potting a wire into a slot in the plastic part. Wire is 0.010 to 0.021 inches in diameter, in a 0.025 inch slot.”

I would suggest you start trials with the DYMAX 1180-M family of adhesives. This series of products cures with UV and visible light, fluoresces for quality purposes, and is available in several viscosities. These adhesives are designed for bonding metal cannula or wires into plastic parts made of PC, ABS, or other plastics.

For application 1, I would recommend DYMAX 1180-M-UR, which has a nominal wicking-grade viscosity of 150 cP and fluoresces bright red.

For applications 2 and 3, DYMAX 1180-M-T-UR could be a good candidate with a nominal viscosity of 6,000 cP. This product also fluoresces red.

Adhesives, Medical cannula bonding, Light Curable Adhesive, light-curable adhesives, Medical-Grade Adhesive, needle bonding, Plastic Bonding, wire bonding

“I would like to attach 72D Pebax extruded tubing into the ID of a Polycarbonate tube. What is the appropriate gap-per-side if I want to use DYMAX 204-CTH UV- curable adhesive?”

The optimum gap size for UV bonding applications (in general) is 0.002-0.006 inches, or 0.05-0.15 mm. In catheter bonding applications, where a Pebax tube is being bonded into a Polycarbonate Y-connector, we often see bond gaps around 0.1 mm per side. The DYMAX 204-CTH-F family is a very good choice of products to use for this type of application and substrate combination. Another product to consider is 208-CTH-F.

Adhesives, Catheter Bonding, Medical 204-CTH-F, 208-CTH-F, bonding Pebex tubing, Catheter-Bonding, Medical-Grade Adhesive, Pebax, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive

“Can you recommend the most appropriate UV-curable adhesive to bond ABS connectors to polyurethane tubing in a medical device application? It is a polyether aromatic polyurethane tube to a transparent ABS connector.”

For this type of application I suggest trying DYMAX 1161-M. This adhesive cures with UV and visible light and exhibits good adhesion to ABS and PUR. It also fluoresces blue for quality purposes. If you are interested in See-Cure patented color-change technology, I would recommend DYMAX See-Cure 1201-M-SC. This product is blue and helps verify that enough adhesive has been dispensed. Upon exposure to UV/visible light, the adhesive turns clear to confirm complete cure.

Adhesives, Medical 1161-M, 1201-M-SC, Light Curable Adhesive, light-curable adhesives, Medical-Grade Adhesive, See-Cure, UV Light Curing Adhesive, UV/Visible Light Curing Adhesive