"We currently use a light-curable acrylated urethane adhesive to bond PVC tubing to a part molded from TPE. We are seeing the adhesive turn yellow and tacky after gamma sterilization and accelerated aging. We also observed the PVC tubing becoming harder in the bond area. These conspire to cause bond failure. The suspect is plasticizer (DEHP) leaching out of the PVC and entering the adhesive. In your opinion, is this the likely cause? Once cured, I would have expected the adhesive to be impervious to DEHP."

I agree that the suspect is the plasticizer migrating during the sterilization and accelerated aging process. Plasticizers like DEHP and BOP will often migrate with heat and time from areas of high concentration to areas of low concentration. It does not matter if the adhesive is cured or uncured. Plasticizers will in effect solvate the adhesive, and migrate into it - often causing it to change color and become gummy or tacky. Just like the plasticizers keep PVC nice and flexible in the cured state, they still migrate away from the PVC under the right conditions. In this case, they migrated into the adhesive, eventually leading to bond failures. This can be tested by subjecting the PVC tubing by itself to the same heating and accelerated aging conditions, and wiping the surface periodically throughout the process. Testing the wipe media for contamination like DEHP or BOP can give an indication of the process step that causes this migration, and how much. Instead of wiping, you can “chemically wash” the part with a proper solvent, collect the solvent, and run it through Gas Chromatography to have it analyzed. To fix the problem, we would recommend trying different PVC tubing with a less mobile plasticizer, or switching to a comparable polyurethane tubing with similar physical properties, but without the need for plasticizer. Changing the chemistry of the adhesive is possible, but a last resort in most cases.

Adhesives, Medical accelerated aging, Adhesives, bond failure, BOP, DEHP, gamma sterilization, gummy, leaching, Plastic Bonding, plasticizer, PVC Tubing, Tack-Free, tacky, TPE, yellowing

A recent question that came through:

“Are there FDA required or recommended adhesives for constructing non-DEHP or
non-phthalate PVC medical devices?”

Response:

That’s a good question and one we are seeing a lot these days. The good news from an adhesive manufacturing standpoint is that many of the adhesives used in medical-device assembly don’t need a plasticizer like DEHP or phthalate-based materials. Most light-curable acrylated urethanes, cyanoacrylates, epoxies, silicones, and polyurethanes do not contain these materials. These adhesive products bond readily to the polymers that are replacing DEHP plasticized PVC, even if they are alternative grades of PVC, extruded silicone, latex, urethane, or other polymer families. Most companies, DYMAX included, are usually asked to provide a letter at the beginning of a project stating that these adhesives do not contain DEHP or BPA.

On a related note, letters similar to the DEHP and BPA letters are available to certify if a product contains material of bovine origin. When Mad Cow Disease came to the forefront a few years ago, the polymers derived from bovine materials became an issue and companies required similar statements from their adhesive and plastic suppliers.

Read more on DEHP and BPA.

Adhesives, Medical BPA, DEHP

REACH, BPA, DEHP, WEEE??? This is not your mother’s alphabet soup but acronyms for new environmental compliance directives, regulations, and initiatives…

As the world shrinks and companies continue to span many continents, we are seeing an increase in global environmental and safety regulations.  Many of these are being initiated in Europe and are spreading throughout Asia and within our own country.  Directives like REACH, WEEE, RoHS, and GHS are driving many companies crazy as they try to understand how the directives affect them.  Initiatives to identify and eliminate DEHP and BPA use in plastics and adhesives are also plaguing many manufacturers.  Very few international companies are immune from these new directives and initiatives.

It’s important to understand each one and how it affects your specific business before investing resources.  In today’s economy companies must invest their resources wisely in order to stay competitive.  It is important to understand the impact of these new regulations and initiatives both financially and from the safety and compliance perspective before moving forward. 

What are they?

REACH, a new European Community Regulation on chemicals and their safe use, entered into law on June 1^st 2007.  The legislation addresses the Registration, Evaluation, Authorization and restriction of Chemical substances.  The main objective of REACH is to improve the protection of human health and the environment from the risks that can be posed by chemicals used in an industry.

REACH makes industries responsible for assessing and managing the risks posed by these chemicals and provides the appropriate safety information to their users.  The criterion is based on volume (equal or greater than 1 metric tonne) imported into the European Union (EU) or if it is a Substance of Very High Concern (SVHC).  Registration of the substances occurs in phases based on the previously mentioned criteria, with the last occurring in 2018.  Learn more. 

WEEE or Waste Electrical and Electronic Equipment is another directive (Directives 2002/95/EC & 2002/96/EC) from the EU which restricts the use of hazardous substances (see RoHS) in electrical and electronic equipment while promoting the collection and recycling thereof.  The recycling program is aimed at re-using electronic waste and encourages consumers to return outdated, broken electronic equipment to the manufacturers at no cost to the consumers.  This eliminates the used electrical and electronic equipment from ever reaching a landfill where it would contaminate the environment with harmful substances that could potentially leech out.  WEEE goes hand-in-hand with RoHS.  Learn more.

RoHS or the Restriction of Hazardous Substances (directive 2002/95/EC) works closely with WEEE and is designed to shift manufacturers away from restricted chemicals to safer alternatives.  The EU identified the following substances under RoHS as hazardous with a significant impact to the environment.  They are: 

• Cadmium (Cd)
• Lead (Pb)
• Hexavalent Chromium (CrVI)
• Mercury (Hg)
• Polybrominated biphenyls (PBB)
• Polybrominated diphenyl ether (PBDE )

Additionally, the EU restricted three other flame retardants under 2003/11/EC for their negative impact on human health and the environment.

• Pentabromodiphenyl ether (PentaBDE)
• Octabromodiphenyl ether (OctaBDE)
• Decabromodiphenyl ether (DecaBDE)

Please click here for more information. 

GHS or Globally Harmonized System of classifying and labeling of chemicals is a regulation that was created in collaboration with the members of the United Nations (UN). Essentially, this regulation looks at unifying and standardizing all classification and labeling of chemicals so they are globally harmonized.  This means whether you are in Russia, France, Mexico, or the United States the safety information would be communicated in an identical manner through pictograms, hazard warnings, signal words, etc.  Read more from the OSHA website. Each specific country’s adoption of this new standard will vary.  Click here to learn more about your specific country’s adoption schedule for GHS.

DEHP and other phthalates

Di(2-ethylhexyl)phthalate (DEHP) is a plasticizer added to polyvinyl chloride (PVC) to make the normally rigid plastic more flexible.  Many companies, especially those in the medical device industry, are requiring suppliers to inform them of DEHP or other phthalate use.  The FDA issued a health warning¹ advising the public that DEHP could leech out of PVC and pose a health risk in certain high risk groups.  Specifically, there are concerns pertaining to the effects on the development of the male reproductive system.  More information is available from the FDA website.   

BPA

Bisphenol A² is a key ingredient in the manufacturing of polycarbonate and a constituent within many epoxies.  “In recent years, a hypothesis has been advanced claiming that exposure to extremely low doses of certain substances could cause adverse health effects in humans, including disruption of normal hormonal functions.”² There have been many conflicting studies completed showing that in some cases there is concern to human health but in other studies demonstrating no harmful effects.  Based on some initial tests through the National Toxicology Program (NTP) it appears as though there is “some concern” especially in small children and infants.  To alleviate some of the discrepancies in testing, NTP is requesting additional information from the scientific community pertaining to the health effects of BPA.³  It may be years before we really know whether there is truly a concern with BPA.  It will probably be too late for industry however, who regardless of the outcomes, will have made the switch to BPA alternatives because of these initial concerns.   More information on BPA can be found here.

Is there any good from these regulations and initiatives?

While many of these regulations and initiatives may be seen as cumbersome and confusing, some of them really are.  They make sense when you look at the overall picture and what is trying to be accomplished.  Many of the regulations are needed to reduce the impact and bioaccumulation of harmful chemicals in the environment, while minimizing or eliminating any risk to the safety and health of the greater population.

DYMAX ECO Benefits Everyone

DYMAX understands that safe ecologically friendly products benefit our customers, the environment, and us. We have created materials with attributes that lower products costs, life-cycle costs, and ecological impact. Learn more…DYMAX Eco underlines the DYMAX commitment to the environment.

¹ Retrieved from the FDA website http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PublicHealthNotifications/ucm062182.htm

² Retrieved from the website http://www.bisphenol-a.org/

³ Retrieved from the website
http://www.ehponline.org/docs/2009/117-3/EHP117pa96PDF.PDF 

Safety BPA, DEHP, GHS, REACH, RoHS, Safety, WEEE