Isocyanates - dangerous allies of paintwork

Isocyanates are a family of highly reactive chemicals found in two-part polyurethane paint systems, main product like varnish or undercoat reacts with hardener that serves as a catalyst. These two-component products are recommended for the durability and high quality of the coating they form. The final coat of lacquer is actually a result of several layers of different types of products that perform several different functions. The first coat layers are responsible for corrosion protection, while the last one is the appearance and durability of the color..

Each layer is created through the application of different type of products. The component that binds these different products are in the vast majority isocyanates - an essential component of hardeners.

When applying paint to a car, we do not consider why a product is characterized by a good scratch resistance or color retention for a long time. We only need the product to meet the highest quality standards, and consequently, we want to receive a durable coating. In the overwhelming number of lacquers on the market, the quality of the chemical bonds in the obtained paint coating corresponds to the isocyanates. However, we have to remember that these are some of the most harmful chemical components, and the painters are most often not aware of their maliciousness.

Take care of your health while you work

While handling with hazardous materials that contain isocyanates, basic rules of safety are advised:

- wear protective clothing to prevent skin absorption,

- use nitrile gloves when mixing and spraying products,

- use nitrile gloves when mixing and spraying products,

- do not use latex gloves as isocyanates penetrate through this type of gloves without their visible damage,

- wear safety goggles,

- spray paint only in properly ventilated spray booths.

It has been proven that isocyanates can cause cancer in animals, so these compounds are classified as potential carcinogens. Occupational exposure to these compounds is considered to be one of the major factors contributing to the development of occupational asthma and it is therefore important to monitor their concentrations in the workplace on a regular basis. Many isocyanates are strong lacrymators, that causes the shedding of tears. The health consequences of contact with isocyanates include irritation of the skin, mucous membranes, chest tightness and difficulty in breathing. The varnisher can work with these substances for years without using any protective clothing and ventilation booth during spray application without any health problems. After some time, the same person for reasons that are not known so far may become allergic to isocyanates. In this situation, even the smallest amounts of toxic substances can cause severe reactions - such as asthma attacks.

Things you should know about isocyanates

Isocyanates are organic substances with properties that allow them to be used in many industries such as pesticide production, but the vast majority of these compounds are used in the production of polyurethane materials. It is worth mentioning the basic property of these substances which is cross-linking. It is not questionable that most of the two-part lacquers consist of a resin and a hardener, i.e. isocyanate. These components, when combined as a result of cross-linking create so called urethane bonding - which are responsible for giving specific properties of the applied coating. It is therefore important to keep the time of drying of the clearcoat in order that all the bindings will give us the desired qualities. They play essential role in the process of creating a durable coating that provides good car paint. Isocyanates improve the chemical resistance and mechanical properties of the paint so that the paint is resistant to scratches and atmospheric conditions.

What’s next ?

Although the technology of producing polyurethanes without the use of toxic substances was discovered as early as 1970-1980, in the automotive industry, coatings based on harmful isocyanates are still predominating. Research on solving a toxic problem continues. Potential solution is the isocyanate-free polyurethane-based technology developed by Hybrid Coating Technologies. Company received the Presidential Green Chemistry Challenge Award in 2015. This is a distinction awarded by the Environmental Protection Agency. The path of excluding toxic substances is long and difficult.

Due to the harmfulness of these substances, an alternative is sought, which while being ecological will keep the desired features of the isocyanates. It is possible to cross-link polyurethanes (PURs) without the use of isocyanates. Hardening is then effected by reaction between polyamines and cyclic hydrocarbons. Non-isocyanate-free polyurethanes exhibit better properties than conventional polyurethanes, and can be used for materials which harden at room temperature. Their tensile strength and deformation are comparable to traditional PURs, but they have lower chemical resistance.

Some manufacturers are already struggling to reduce the consumption of isocyanates. An example of this is the CP 2015 HS X-SPEED paint from Profix, which uses the latest generation of resins to minimize the need for harmful compounds. As long as we do not deregulate completely from harmful hardeners, it is essential to observe the basic safety rules when handling with these substances.