“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.

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“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.

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“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

“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.

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“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.

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“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.

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“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

“Do you have an FDA-approved adhesive for artificial hearts (structural and non-structural adhesive)? Which standard is more relevant and which standard applies - ISO 10993, USP Class VI, or another standard?”

If you are referring to implantable artificial hearts, we have to pass. DYMAX adhesives have not been tested for prolonged or permanent implantation and are only intended for use in short-term (<29 days) or single-use disposable device applications. DYMAX does not authorize their use in long-term implant applications.

Polymerized DYMAX MD^® Medical Device adhesives are biocompatibility tested in accordance with ISO 10993 and/or USP Class VI. ISO 10993 is a newer, internationally accepted standard. The current DYMAX test protocol for medical adhesives contains the following studies:

• ISO 10993-4 Hemolysis
• ISO 10993-5 Cytotoxicity
• ISO 10993-6 Implantation 14 Days
• ISO 10993-10 Intracutaneous
• ISO 10993-11 Systemic Toxicity

Older DYMAX adhesives have been tested in accordance with USP Class VI, which consists of Systemic Toxicity, Intracutaneous and a 7-days Implantation Test. When comparing both standards, USP Class VI is included in and covered by ISO 10993.

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“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.

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