What are acrylates?

Acrylates are esters, salts or conjugate bases of acrylic acid. They have a characteristic double bond between two carbon atoms (vinyl group) and a carboxylic acid function, which is present in the form of an ester or salt. Due to their chemical structure, they are reactive and polymerise easily, making them ideal starting materials for plastics, paints, adhesives, coatings and numerous other applications. Acrylates are used in many industries, from construction and automotive to cosmetics.

Formation

Acrylates are produced industrially by the esterification of acrylic acid with various alcohols. This reaction usually takes place at temperatures between 100 °C and 120 °C using acid catalysts such as sulphuric acid or p-toluenesulphonic acid. For higher alcohols, titanium or tin compounds are often used as catalysts. In some processes, transesterification with lower acrylates is also carried out. Stabilisers such as hydroquinone monomethyl ether (MEHQ) are added to prevent unwanted polymerisation.

Identification

Acrylates usually appear as colourless to slightly yellowish liquids with a pungent, often sweetish chemical odour. They are highly volatile and readily soluble in many organic solvents. Due to their reactivity, they tend to polymerise spontaneously at elevated temperatures or under the influence of light. For this reason, they are almost always mixed with stabilisers and stored in opaque containers. When released, acrylates are often detectable by their odour even in low concentrations.

Limit values

The permissible occupational exposure limits for acrylate monomers depend on the substance in question. For many representatives, the limit values in the European Union are between 100 and 200 ppm (approx. 0.5–1 mg/m³). Some acrylates, such as methyl methacrylate or ethyl acrylate, have specific, legally defined limit values that are regulated in the Technical Instructions on Air Quality Control (TA-Luft) or in TRGS 900.

Hazards

Acrylates irritate the skin, eyes and respiratory tract. Even brief exposure can cause redness, burning and watery eyes. Prolonged or repeated skin contact may lead to the development of allergic reactions, especially in occupational groups with regular contact, such as nail cosmetics or paint processing. Some acrylates are suspected of being carcinogenic or mutagenic. In the environment, acrylates can damage aquatic organisms due to their reactivity and impair air quality through volatile emissions.