“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
“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.
“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.
“I am having a hard time bonding polyethylene. Will texturing the surface of my substrate with microblasting improve the bond adhesion?”
Creating a texture on the surface will help with adhesion, however, the surfaces must be free of any dust or particles prior to bonding. An IPA wipe should be sufficient for cleaning. With some hard to bond plastics like polypropylene, silicones, HDPE, etc., this kind of abrasion may have minimal impact for bond strength.
“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.
“We currently employ a solvent process using Cyclohexanone to bond a PVC tubing with an ABS molded hub. We are going to be switching from ABS to a Pebax (thermoplastic elastomer). We believe there are issues with the Cyclohexanone creating the bond with the Pebax that we desire, and I’m looking for some info regarding our process – is it appropriate to continue to solvent bond (maybe with a different solvent) or to switch to a new process (UV adhesive for example)?”
Solvent bonding typically works with amorphous thermoplastics such as PVC, ABS, PC, PMMA, and PS. Pebax belongs to the family of thermoplastic elastomers and has a good resistance to solvents in general. Depending on the grade and softness, it may swell in certain solvents but will not behave like amorphous thermoplastics do. If you replace the ABS with Pebax, you need to switch to a new bonding process. UV light-curable adhesives are a good option. I would recommend trying Dymax medical grade adhesives 204-CTH-F and 209-CTH. They both adhere well to PVC and Pebax and several other commonly used plastics.
“I am trying to adhere a Polyethylene (PE) foam material onto a Polyethylene (PE) rigid, smooth plastic material. I prep both surfaces with a primer (Loctite 7701) before dispensing the adhesive, which is Loctite’s 4011 cyanoacrylate medical-grade adhesive. The adhesive is anchoring or sticking really well to the PE foam, but not the rigid plastic. They are both PE materials and I am not sure why it would adhere to one and not the other.
Are there different primers that vary in performance?”
One reason why the adhesive might stick better to the foamed Polyethylene (PE) is its larger surface. Due to the holes and grooves, adhesives in general can hold on better and achieve a mechanical lock.
According to the suppliers web site, the primer you are using is recommended for PE. If it is not providing the desired results, you may want to look into another surface treatment method such as plasma or corona, which adds polar groups to the surface and usually results in higher bond strengths.
“I would like to know the best adhesive to use in our cannula and metal-wire bonding processes. The details are as follows:
1. Stainless cannula to PC – need wicking grade, with black light confirmation if possible.
2. Stainless 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.
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.
“I need to bond a plastic cap to an alloy/some type of metal shaft. The application is really similar to the two bottom joysticks of a playstation controller where you have the plastic cap that bonds on the resistive joysticks made of an alloy/some type of metal shaft. Any ideas about what adhesive might work best?”
Without knowing what the plastic is, the size and what type of environment this will be exposed to, it is difficult to make an accurate recommendation. However, based on what you provided we would recommend looking at a cyanoacrylate (instant adhesive).
“We want to bond Polyurethane to PU, Polyurethane to latex, and PU to polycarbonate. A little flexibility would be helpful. Visibility of the bond would also be desirable. Do you have a product that meets these requirements?”
DYMAX offers 204-CTH-F light-curable adhesive, which is recommended for single-use medical devices made of Polyurethane, PVC, Polycarbonate, and many other plastics. This adhesive fluoresces blue under black light for quality purposes and is suitable for assembling rigid and flexible components due to its flexibility.
Since latex is very difficult to adhere to, 204-CTH-F may not provide the desired bond strength. Typically, a cyanoacrylate like DYMAX 222 Series is used for latex; however, it will not provide a flexible bond.
If you want to be able to see the adhesive while you dispense it and get confirmation of cure, I would suggest trying DYMAX 1201-M-SC or 211-CTH-SC. Both are light-curable adhesives equipped with DYMAX patented See-Cure color change technology. Adhesives formulated with See-Cure technology are visible when dispensed onto substrates due to their bright blue color while in the uncured stage. When fully cured, they become colorless to visually assure they have been cured.