“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.
“We use 1184-M-T, 1184-M-B, and 1184-M-VT epoxies for various uses. What is a good solvent that can take apart lenses glued together using 1184-M-T adhesive?”
If your lenses are made of glass you have several options, as glass is resistant to the solvent removal methods suggested below:
There are a few chemicals that will dissolve or swell 1184-M-T or any other light-curable acrylate, such as Dichloromethane, MEK, or Acetone. It may take some time for the solvent to migrate all the way in between the laminate, so the time depends on the size of your parts. A more gentile method is to soak the lenses in isopropyl alcohol (IPA) or even use warm IPA with the help of an ultra-sonic cleaner. I would also suggest this method if your lenses are made of plastic since the solvents mentioned first will also damage it.
“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
“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.
“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).
“I am interested in a low-viscosity epoxy (<100 cp) with good adhesion to ceramics and stainless steel. The objective is to seal a small metal sensor inside a ceramic casing at room temperature. There is no contact with the patient. What type of epoxy do you recommend?"
Based on the substrates, ceramic and stainless steel, and the room-temperature requirements, I would recommend looking at a cyanoacrylate (instant adhesive) or a two-part epoxy.
Cyanoacrylates are available in very low viscosities. You may want to evaluate the DYMAX 222 Series which offers cyanoacrylates in a variety of viscosities. Low-viscosity epoxies are rare. One option could be two-part epoxy 301 from EPO-TEK, which is 100-200 cP.
“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 am trying to bond 304 stainless steel to 304 stainless steel without welding. A strip of stainless steel is put into place once the device is completely assembled and welding would damage sensitive electronic components. The strip of stainless steel is currently held in place with high bond-strength double-sided tape with foam between the adhesive layers. The foam helps the strip to take its shape over slight surface variations in the welded cabinet it is being affixed to. The problem is that the foam can be shifted over allowing access to what is behind the strip. Pry bars have then been used to gain access into the device. It has been difficult to find an adhesive that can allow for surface irregularities. The adhesive must be able to withstand outdoor temperature extremes, moisture, and UV since this device can be permanently installed anywhere. The adhesive must also have other special properties because the strip is installed vertically to the cabinet and it is done on a shop floor where there are a lot of people around. Any ideas?”
For such extreme environment requirements and gap configuration, a 2-part epoxy could possibly be the best solutions for this application.