Messi Biology states that during the scorching summer days, we always apply sunscreen before going out to protect our skin from UV damage. In fact, the plastic products in our daily lives—such as agricultural mulching films, outdoor furniture, and automotive bumpers—are equally vulnerable to sunlight. When exposed to ultraviolet rays for long periods, plastics become brittle, fade, and even chalk. To protect them, scientists have provided plastic materials with a “sunscreen coat”—this is where light stabilizers come in. Among numerous light stabilizers, magnesium hydroxide, as a novel and eco-friendly inorganic material, is gradually becoming a new favorite in the industry.
Traditional organic light stabilizers (such as hindered amine light stabilizers), although effective, often suffer from easy volatilization, poor high-temperature resistance, or decomposition during processing. In contrast, magnesium hydroxide (Mg(OH)2), an inorganic material, derives its core functional mechanism from its unique physical and chemical properties.
First, magnesium hydroxide exhibits excellent UV-shielding capabilities. It can efficiently absorb and scatter ultraviolet rays in sunlight, preventing UV radiation from penetrating deep into the plastic material to destroy polymer chains, thereby cutting off the pathway of photo-aging reactions at the source. Second, magnesium hydroxide acts as an “acid gas scavenger.” During the photo-oxidative degradation of plastics, trace amounts of acidic byproducts (such as hydrogen chloride) are often generated, which in turn accelerate material corrosion and aging. Being weakly alkaline, magnesium hydroxide can neutralize these acidic gases, thereby providing an auxiliary stabilizing effect.
If light stabilization is a “side job” for magnesium hydroxide, flame retardancy is certainly its “main profession.” Magnesium hydroxide is a widely recognized halogen-free, eco-friendly flame retardant. When heated, it decomposes to release bound water, a process that absorbs a large amount of heat and lowers the surface temperature of the material. Simultaneously, the generated water vapor dilutes combustible gases, while the resulting magnesium oxide residue forms a high-temperature-resistant insulating layer. Combining light-stabilizing and flame-retardant functions into one is a major advantage of magnesium hydroxide. For outdoor wires, cables, and building materials that require both resistance to weathering and fireproof performance, using magnesium hydroxide achieves “two birds with one stone,” reducing the dosage of other additives in the formula, simplifying the production process, and lowering costs.
With the increasingly stringent global environmental regulations, heavy metal stabilizers containing lead or cadmium are gradually exiting the historical stage. Magnesium hydroxide is non-toxic, odorless, non-corrosive, and exhibits significant smoke suppression, fully complying with environmental directives such as the EU’s RoHS. In addition, magnesium hydroxide has widely available raw materials and a relatively low price, giving it extremely high cost-effectiveness in large-scale industrial applications.
From long-lasting agricultural greenhouse films to durable outdoor plastic profiles, light-stabilizing magnesium hydroxide silently safeguards the service life of materials through its unique UV-shielding, acid-neutralizing, and exceptional flame-retardant properties. It is not only the “sunscreen” of the plastics industry but also a green guardian of environment and safety. With the advancement of nanotechnology, the research and development of nano-magnesium hydroxide will further enhance its dispersibility and stability. In the future, this white powder will undoubtedly shine even brighter in the field of new materials.