Published June 2014
Acrylic acid and esters are versatile monomers used as building blocks for thousands of polymer formulations. They are flammable, reactive, volatile liquids based on an alpha-, beta-unsaturated carboxyl structure. Incorporation of varying percentages of acrylate monomers permits the production of many formulations for latex and solution copolymers, copolymer plastics and cross-linkable polymer systems. Their performance characteristics—which impart varying degrees of tackiness, durability, hardness and glass transition temperatures—promote consumption in many end-use applications. Major markets for the esters include surface coatings, textiles, adhesives and plastics. Polyacrylic acid or copolymers find applications in superabsorbents, detergents, dispersants, flocculants and thickeners. Superabsorbent polymers (SAPs) are used primarily in disposable diapers.
The following pie chart shows world consumption of acrylic acid:
Crude acrylic acid must be purified to glacial acrylic acid, which is used to produce superabsorbent polymers and polyacrylic acid and copolymers used as dispersants/antiscalants, anionic polyelectrolytes for water treatment and rheology modifiers. In 2013, global glacial acrylic acid consumption was estimated to account for about 45% of total crude acrylic acid consumption. Growth is forecast at 5.4% annually during 2013–2018. More information on the superabsorbent polymers market can be found in the CEH Superabsorbent Polymers report.
Acrylate esters impart many desirable qualities to polymeric materials, such as color stability and clarity, heat and aging resistance, good weatherability and low-temperature flexibility. One of the important properties of acrylate esters is their glass transition temperature (Tg), which influences the characteristic temperature at which the resultant polymer undergoes a change from a brittle system to a softer, more flexible one. The Tg has a major influence on the minimum film formation temperature of the coating or adhesive. (The minimum film formation temperature is also influenced by the levels and types of cosolvents and coalescing agents, plasticizers and other additives added to the polymer or to the coating formulation.) The shorter-chain monomers (e.g., methyl acrylate) produce harder, more brittle polymers, while the longer-chain monomers (e.g., 2-ethylhexyl acrylate) impart softness and flexibility.
Growth in demand for crude acrylic acid is forecast at almost 4.5% annually during 2013–2018, driven by growth in superabsorbent polymers at 4.8% and acrylate esters at 4.3%. SAP growth will be strongest in China (expected growth in production is 13–14% per year for 2013–2018) and other areas of Asia (e.g., the Republic of Korea and Indonesia), but will be much more moderate in the mature regions of North America, Western Europe and Japan. The strong SAP growth in Asia is strongly influencing the industry to expand capacity for both crude and glacial acrylic acid, especially in China.