Nonylphenol in your epoxy resin
1:1 Epoxy Resins
Ever since epoxies gained significant popularity among the woodworkers and crafts makers, manufacturers and distributors of epoxy resins in North America started to promote their "tabletop" "arts" "crafts" etc., fast curing 1:1 (one to one) by volume mixing ratio epoxy formulations designed for coatings, so-called "decoupage coatings". When you consider purchasing a 1:1 resin for arts, tabletops, crafts or other applications, there is a significant (almost guaranteed) chance that the product will contain nonylphenol.
Filling The Gap In the Formulation
By the nature of the chemistry involved in the development of epoxy resins, a standard mixing ratio for unmodified Part A / Part B compounds would lie in the range of 1.8:1 - 3:1. Therefore, a 1:1 by volume mixing ratio is achievable if part B (hardener or cross-linker) is modified with a filling compound. Ideally, this filling compound should be compatible with epoxy resins such that it should be transparent, possess workable viscosity, and cause a reaction to accelerate to allow the curing process to complete in 24 hours or less. Importantly, it should not cause deterioration of the properties of the cured resin such as a decrease in glass transition temperature down to the level where epoxy coating becomes soft under even slightly warmer conditions than the room temperature.
Such a compound was found: "Nonylphenol"
Nonylphenol has been an attractive choice for the modification of part B of the epoxy resin system for more than 15 years. Due to a particular chemical group (hydroxyl group "OH"), it causes the acceleration of epoxy resin curing reaction, Nonylphenol is a forgiving compound and it allows a chemical formulator to use it in high concentrations. If you are using a 1:1 epoxy system for your arts or crafts project, most likely your epoxy product contains Nonylphenol in concentrations of 40-65% of part B (hardener). You can check it by yourself by downloading the Safety Data Sheet from your manufacturer's website or requesting it from the distributor. Section 3 of the Safety Data Sheet of Part B of the epoxy product should contain information on whether your 1:1 epoxy system contains Nonylphenol or not.
Why Should You Avoid Using Products Containing Nonylphenol?
As a team of chemists and engineers, after researching the current epoxy market, we found concerning claims of the epoxy resin manufacturers and distributors about the safety of their products. "Low VOC", "Zero VOC", "Safe to breath", "The Safest Epoxy" and other claims are being made to promote the product and grow sales. The reality is that these claims could be misleading at the very least or even dangerous for an epoxy user. For example, an epoxy formulation can be made without the usage of volatile organic compounds (Zero VOC), but the lack of volatile organic compounds is not a panacea that is making epoxy "safe". In fact, in the pursuit of profits, many of these manufacturers enter dark grounds claiming their products are safe to use. Chemical compounds can possess various types of health hazards: immediate and those which could potentially cause damage but the specificity of the damage is not easily detectable or traceable. While hazards like skin corrosion/irritation, eye damage, and others can cause serious harm, usually the immediate nature of these hazards allows to prevent them by using appropriate personal protective equipment and good practices when working with chemicals. On the other hand, some of the potential health hazards are not as easily detectable or they tend to occur after repeated exposure including the following:
GERM CELL MUTAGENICITY
TOXIC TO REPRODUCTION [Fertility]
TOXIC TO REPRODUCTION [Unborn child]
SPECIFIC TARGET ORGAN TOXICITY (REPEATED EXPOSURE): SKIN [central nervous system (CNS)]
WHMIS (Workplace Hazardous Materials Information System) pictogram for health hazards is shown below.
Depending on the regulatory requirements for the particular region, if a chemical product such as an epoxy system is available to purchase, it may or may not require the health hazard pictogram to be shown on the label. For example, there is no requirement for this WHMIS pictogram in Canada to be present on the product package, but it will still be present in the Safety Data Sheet.
Below you can find a list of Nonylphenol's health hazards in its pure form:
ACUTE TOXICITY: ORAL - Category 4
SKIN CORROSION/IRRITATION - Category 1B
SERIOUS EYE DAMAGE/ EYE IRRITATION - Category 1
GERM CELL MUTAGENICITY(Suspected of causing genetic defects) - Category 2
TOXIC TO REPRODUCTION [Fertility] - Category 2
TOXIC TO REPRODUCTION [Unborn child] - Category 2
SPECIFIC TARGET ORGAN TOXICITY (REPEATED EXPOSURE): SKIN [central nervous system (CNS)] - Category 2
A Delayed Hazard
Mutagenicity, toxicity to reproduction, and specific target organ toxicity are those hazards that could be hardly traceable but very dangerous because of the delayed observance of those. It is a topic for debate whether 40-65% concentration of Nonylphenol in part B of epoxy resin formulation will cause these adverse effects or not, what are the routes of exposure, and how long an individual should be exposed to start experiencing any of these health issues. At the same time, our team finds the practices of some of the other manufacturers questionable at the very least, when they claim their products which contain nonylphenol - "the safest" or any other marketing expression.
In our opinion, the right way to address the presence of a certain compound that could possess hidden effects for health is either to simply not use it or, to take some effort to communicate to customers all of the potential dangers of these constituents, especially when the customers often have not dealt with such a class of materials before, thus being more vulnerable to exposure to potentially harmful components.
Nerpa Polymers does not use Nonylphenol in our products. Our R&D team has developed a coating resin that maintains the properties you love such as 1:1 by volume mixing ratio, 45 minutes working time, 24 hours dry through cure, Shore D hardness 80+, UV Protection, 7 days full cure in our high viscosity Nerpa Coating Epoxy without the use of Nonylphenol. Instead, our team found a solution with a newer, advanced alternative to Nonylphenol that does not have these potential health hazards which Nonylphenol has.
Please be advised, that Nerpa Polymers insists on using personal protective equipment such as gloves and safety glasses anyways because components of the epoxy resins in their liquid state are reactive and considered to be irritants and corrosive to skin and eyes.