Methacrylates are a class of “building block” chemicals used to make polymers and plastics that have a wide range of beneficial features, including stability, durability, hardness and scratch resistance. The term “methacrylates” is used here to denote both methacrylic acid and its methacrylate ester derivatives.
Uses & Benefits
Methacrylates are used in a range of industries and applications, including:
Electronics and Computers
The electronics and computer industries use methacrylate-based polymers to manufacture flat-screen computer monitors and televisions, as well as in DVDs, compact discs and laser discs. Printed circuit board coatings also contain methacrylate polymers, which can provide them with increased resistance to corrosion, prolonging their service life.
Medical and Dental Applications
Methacrylate-based polymers are used to manufacture a wide range of medical equipment and other medical and dental applications where purity and stability are critical – from intravenous (IV) tubing connectors, medical pump and filter housings and heart valves, to hyperbaric chambers and baby incubators, artificial teeth, dentures, bridges and dental prosthetics. Cements containing methacrylate-based polymers and liquid monomer are used by physicians in hip replacements and by dentists in white dental fillings with liquid monomers polymerized in situ.
Paints and other Surface Coatings
Most types of acrylic paint contain one or more methacrylate-based polymer products, which help enable paints and coatings to be applied easily, while producing a durable, long-lasting coating that helps protect the surface from sunlight, rain and other factors that may cause other types of coatings to degenerate. The durability of methacrylate-based polymers is important in the vast majority of applications and can be critical in some, such as roadway marking paints.
Acrylic Cast and Extruded Sheets
Polymethylmethacrylate (PMMA) and PMMA-based sheets help form shatter-resistant, clear and colored sheets for building windows, skylights, bus shelters, bullet proof security barriers, signs and retail displays, among other applications. PMMA also can be used with a mineral filler to make artificial stone for kitchen and bath countertops and sinks.
Acrylic Resin
Beads or pellets made from methacrylate-based polymers can be molded into many other end use articles, such as taillights and instrument clusters for cars and trucks, knobs on sink faucets and other home appliances, and light lenses in commercial buildings and airport landing lights.
Safety Information
Consumer exposure to methacrylate monomers from finished products made with methacrylate-based polymers is typically very low, and both oral and dermal exposures under normal use are considered to be negligible.
In some products like glues or cements, varnishes or other finishes, consumers may be exposed to liquid monomers until the adhesive or coating cures or dries. For these materials, package labels provide safety information, including instructions to use the product in a well ventilated area and prevent skin contact.
Exposure to methacrylate monomers is most likely to occur through worker inhalation and skin contact during production, transportation or use of these compounds. The U.S. Occupational Safety & Health Administration (OSHA) has defined a Permissible Exposure Limit (PEL) for methyl methacrylate of 100 parts per million (ppm) for an 8-hour time-weighted average, or the average value of an exposure over an 8-hour work shift.
Answering Questions
What are the health effects of exposure to methacrylates?
Methacrylates are generally of low toxicity, have not been found to damage reproduction or harm the unborn child, and studies in workers exposed to methacrylates for more than 30 years indicate that there is no increased risk of developing cancer due to occupational exposure. Some methacrylates can cause skin sensitization, or an allergic reaction or rash, in people exposed to the chemical. Several international agencies have looked at the available information and concluded that the available evidence does not support a causal connection between MMA and development of asthma, though methacrylates can irritate the skin, eyes and respiratory system, and breathing high levels of MMA vapor may provoke an asthma attack in a person that already suffers from asthma.
How are consumers exposed to methacrylates?
Exposure to the liquid monomers occurs primarily in the workplace, where facilities must train workers and provide them with appropriate equipment to control exposure. Consumer exposure to methacrylates from finished products made with the polymers is typically very low, and both oral and skin exposures are considered negligible under normal conditions of use. In some products like glues or cements, varnishes or other finishes, consumers may be exposed to low levels of liquid monomers until the adhesive or coating cures or dries. For these materials, package labels provide safety information, including instructions to use the product in a well ventilated area and prevent skin contact.
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