Superabsorbent Polymers: Uncovering the Secret of Water Absorption
Superabsorbent polymers (SAP) or slush powder are class of cross-linked hydrophilic polymers that are engineered with high affinity towards liquid absorption. Superabsorbent polymers can retain exceptionally large amount (about 300-500 times their weight) of aqueous fluid compared to its own mass. Once the aqueous fluid is absorbed, SAP does not release it. Superabsorbent polymers utilize osmotic pressure for liquid absorption, thus making it ideal material for the products designed to contain fluids such as disposable hygiene products. Disposable hygiene adhesives are then used to stabilize the fluff and superabsorbent polymer matrix.
Acrylic acid (Na or K salts), sodium hydroxide, and acrylamide are the key raw materials for manufacturing of superabsorbent polymers. They are synthesized via three key processes: gel polymerization, inverse-suspension polymerization, and solution polymerization. Polymerization of acrylic acid is blended with sodium hydroxide, UV initiator, and cross-linking agents to form polyacrylic acid salt (sodium polyacrylate).
Sodium Polyacrylate Continues to be the Most Popular Product
In 2019, the estimated demand for superabsorbent polymers was around 3.0 million tons. Superabsorbent polymers can be classified as synthetic (petrochemical based) or natural (polysaccharide or polypeptide based). Sodium polyacrylate, polyacrylamide, ethylene maleic anhydride copolymer, and polyvinyl alcohol are the most common types of superabsorbent polymers available in the market. Sodium polyacrylate is the most manufactured superabsorbent polymer and accounted for more than 80% of the total SAP production worldwide in 2019. However, in case of agriculture applications, potassium polyacrylate is the preferred product as after rain or irrigation it tends to gel the absorbed water, unlike sodium polyacrylate which will not release water and let soil harden.
Sodium polyacrylate is used in wide range of hygiene as well as non-hygiene applications. These polymers are used in agriculture as well as industrial applications such as waterproofing materials, cooling materials, cable wrapping tapes, etc. Growing demand for disposable and personal care hygiene products such as baby diapers, sanitary pads, and adult incontinence products has been the key factor behind the robust growth of sodium polyacrylate.
Hygiene Led by Diapers to be the Largest Consumer of Superabsorbent Polymers
Almost 90% of the total SAP consumed worldwide is for disposable and personal care hygiene products. Diapers accounted for more than 3/4th of the total demand for superabsorbent polymers in 2019. SAP has been a revolutionary material to the diaper industry with successful replacement of traditional materials such as cloth, cellulose fiber, and cotton. Superabsorbent polymers keep the skin dry and protects from skin irritation.
Demand for disposal hygiene products is heavily influenced by multiple factors such as rising disposable income levels, birth rates, increasing number of working women, and ageing population, consequently driving the volume growth of superabsorbent polymers. Furthermore, growing health and personal hygiene awareness in the developing economies is projected to boost the demand for SAP over the coming years. Other applications such as agriculture, medical, and industrial are also expected to offer lucrative growth opportunity during the forecast period.
North America Remains Largest Market, Asia Pacific to be the Fastest Growing Region
Currently, North America is the largest consumer of superabsorbent polymers accounting for nearly 1/3rd of the total consumption. The disposable diapers penetration rate in the region is more than 90% and is expected to exhibit sluggish growth as birth rates dwindle. However, with ageing population and greater acceptance of incontinence products, the demand for adult incontinence products is expected to drive superabsorbent polymers market in the region.
Asia Pacific is projected to be the fastest-growing market. Factors such as rising disposable incomes, changing consumer preferences, and growing hygiene awareness in countries such as India, China, and Southeast Asia is anticipated to boost the SAP demand. The region is also expected to witness high birth rates and increased penetration rates for baby diapers, except Japan. Japan has more than 90% penetration rate for disposable diapers; however, industry players are depending upon growing elderly population to drive the need for adult incontinence products.
Companies Focusing on Capacity Expansion and New Product Innovation
The market for superabsorbent polymers is highly consolidated. Companies such as Nippon Shokubai, Evonik Industries, BASF SE, SAP Global, and Sumitomo Seika Chemicals together accounted for more than 60% of the total superabsorbent polymers production in 2019. Companies operating in the market have technological advantage enabling them to control over the market. Currently, there seems to be overcapacity in the market due to cost competitive China-based manufacturers. However, the capacity expansion tends to come over the course of time due to rising demand from hygiene and non-hygiene applications. In 2019, LG’s new SAP capacity came on stream along with crude acrylic acid. The company invested US$278 Mn for the expansion, allowing the company to strengthen vertical integration position in propylene processing.
The companies are focusing on product innovation to solve issue regarding odor, leakage, rashes in hygiene product. In 2019, LG and Archer Daniels Midland Company (ADM) signed a joint development agreement (JDA) to create 100% biobased acrylic acid production and build a sustainable technology for SAP. Furthermore, LG plans to review construction of bio superabsorbent polymer production facility in North America.