Despite their diminishing use in some areas, solvent-based coatings remain key components in the global marketplace. Freedonia Group, Inc. predicts that world demand for solvent-based coatings will rise 2.4% per year to reach 17.1 million metric tons in 2005. Growth, while slow, is an improvement over numbers posted in the last decade. What's behind the increase? The use of solventborne paints in underdeveloped markets like Eastern Europe, Asia-Pacific and Latin America.
In the U.S., latex coatings accounted for the vast majority (more than 80%) of all architectural paint production in 2000. Yet oil-based technologies still occupied a healthy share of the market (approximately 20%), thanks to the continued popularity, performance and aesthetic appeal of stains, sealers and high-gloss paints.
For solvent-based applications, formulators are focusing on higher solids products. In 2000, high solids coatings accounted for 2.5 million metric tons-some 15%-of the total demand for solvent-based coatings. Those numbers are expected to double by 2005, according to Freedonia.
There is also the continued shift in the type of solvents used by paint formulators. For example, companies are replacing hydrocarbons with oxygenated products that are a better fit with today's more stringent environmental mandates.
Suppliers are offering paint companies solutions for their solvent needs, ranging from replacements to environmentally sensitive products.
Lyondell Chemical is still waiting for the green light on the VOC-exempt status of TBAc (tertiary-butyl-acetate), a non-HAP ester solvent for coatings, inks and adhesives. Unlike other esters, TBAc does not react with amine curatives and is an alternative to toluene and xylene for two-component epoxy coatings.
Lyondell also offers NMP (N-methyl-pyrrolidone), a non-HAP coalescent for waterborne acrylics and urethane dispersions. NMP is the solvent of choice for the preparation of polyurethane dispersions, according to the company, and is also an effective adhesion promoter for waterborne coatings and inks on certain plastic substrates.
Lyondell's Arconate PC HP (propylene carbonate) is a non-HAP intermediate and reactive diluent for low-VOC coating systems. It reacts with amines to produce carbamates and offer a non-isocyanate route to urethane products.
ExxonMobil Chemical offers paint formulators a range of products, including Exxate fluids, Glydexx esters, Exxsol D fluids and methyl ethyl ketone (MEK), which can replace MIBK, acetone, ethyl acetate and methyl acetate in automotive, industrial, maintenance, traffic and furniture coatings.
Exxate fluids are a versatile, low vapor pressure product for architectural waterborne, industrial, traffic and maintenance coatings. Benefits of this technology include a wide evaporation range, reduced dry times, faster film hardness, improved water resistance and excellent coalescing power.
ExxonMobil's Glydexx esters can be used in automotive, industrial and maintenance coatings to provide enhanced impact, chemical and salt spray resistance as well as improved adhesion. As a reactive diluent, it provides enhanced chemical, water and impact resistance as well as flexibility.
Exxsol D fluids, which are used in solvent-based architectural and maintenance coatings, typically replace mineral spirits and aliphatic hydrocarbons. They are characterized by low aromatics content for reduced HAPs and odor. Available in a wide range of volatility, Exxsol D fluids have low surface tension and good solvency power.
Dow Chemical officers butyl Cellosolve acetate and butyl Carbitol acetate. These ethylene-based glycol ether acetates have low reactivity and excellent organic solubility properties. While they are typically more hydrophilic than propylene-based glycol ether acetates, they are well suited for one- and two-component solvent-based coatings, according to Dow.
Also from the Dow stable are Dowanol PnB series glycol ethers. These butanol initiated propylene-based glycol ethers are very hydrophobic, yet they maintain partial water solubility. The water/organic balance gives PnB series products excellent versatility in latex coatings as efficient low odor coalescing agents.
The Dowanol PnP series of glycol ethers exhibit high water solubility with mild hydrophobic properties. In applications where the latex may be sensitive to extremely hydrophobic coalescents, it can offer a balanced product for optimal stability.
Dow's hexyl Carbitol displays strong hydrocarbon solvency and low water solubility. A slow evaporating solvent, it effectively reduces film formation temperatures in waterborne coatings and contributes to good flow and leveling in high-solids coatings during dry cycles, according to Dow.