Messi Biology states that spandex, known as the “King of Elasticity” in the textile field, is widely used in close-fitting garments such as swimwear, sportswear, and underwear due to its excellent stretch and recovery properties. However, spandex has a fatal weakness: poor chlorine resistance. Chlorine components found in swimming pool disinfectants and bleaches can rapidly destroy the molecular structure of spandex, causing garments to lose elasticity, turn yellow, and become brittle. Magnesium carbonate, a common inorganic compound, is becoming a key material in solving the challenge of spandex chlorine resistance, playing the role of an “invisible guardian” in the textile industry.
The ability of magnesium carbonate to fulfill this mission stems from its unique physicochemical properties. As a white amorphous powder, magnesium carbonate possesses good dispersibility and thermal stability. During the spandex spinning process, it can be uniformly dispersed within the polymer matrix without affecting the formation or basic performance of the fiber. More importantly, magnesium carbonate features weak alkalinity and excellent chlorine-capturing capabilities, which are its core advantages in enhancing the chlorine resistance of spandex.
In the production of spandex, magnesium carbonate mainly functions through addition during spinning. Manufacturers mix a specific proportion of magnesium carbonate powder with spandex raw materials—such as polyether or polyester polyols and diisocyanates—which then undergo polymerization and spinning. When spandex fibers containing magnesium carbonate are exposed to a chlorine-containing environment, the magnesium carbonate reacts with the chlorine first. It converts active chlorine into stable chlorides, preventing chlorine molecules from attacking sensitive groups like urea and ester groups in the spandex molecular chain, thereby protecting the fiber structure. This “sacrificial protection” mechanism significantly delays the aging speed of spandex in chlorinated environments.
In addition to capturing active chlorine, magnesium carbonate can regulate the micro-environment of the spandex fiber. Chlorine disinfectants often make water bodies acidic, and the weak alkalinity of magnesium carbonate can neutralize some acidic substances, reducing acid erosion on the spandex. Simultaneously, the addition of magnesium carbonate can improve the crystallinity of the spandex fiber and enhance its structural compactness. This further blocks the penetration of chlorine molecules, forming a “physical + chemical” dual protection system.
In practical applications, the addition amount of magnesium carbonate must be precisely controlled, typically accounting for 1% to 5% of the total mass of spandex raw materials. If the amount is too low, the ideal chlorine resistance cannot be achieved; if the amount is too high, it may affect the elasticity and softness of the fiber. Spandex modified with magnesium carbonate can see a 3 to 5-fold increase in chlorine resistance. Even after long-term immersion in pool water, it maintains good elasticity and appearance stability, significantly extending the service life of related textile products.
Today, with the increasing popularity of leisure activities such as fitness and swimming, the market demand for chlorine-resistant spandex continues to grow. Magnesium carbonate, as an efficient and environmentally friendly chlorine-resistant modifier, is being applied more and more widely. This small inorganic compound not only solves key technical difficulties in the spandex industry but also brings more durable and comfortable textile products to consumers, building a practical bridge between material science and daily life.