As a subset of industrial cleaning agents, hydrocarbon solvents are the most popular ones. They are petroleum-based solvents having hydrogen and carbons as the main elements of their chemical structure. There are two main categories of hydrocarbons solvents: Aliphatic solvents such as gasoline, kerosene and hexane that have straight hydrocarbons chains and are typically used for metal cleaning. Aromatic solvents, on the other hand, contain benzene ring structures and are widely used in the manufacturing of paint thinners, paint strippers, inks, etc. Examples in this category include toluene and xylenes.
Toluene has applications in paints, lacquers, thinners and glues manufacturing as a solvent and xylene (mixture of three xylene isomers and traces of other aromatic compounds) is the typical solvent that is employed for removing grease, waxes and oil as well as stripping and thinning for solvent based acrylic (SBA) sealers.
Despite being the two most common industrial solvents, there are health hazard associated with the use of toluene- and xylene-based solvents. The main effect of inhaling toluene and xylene vapors are depression of the central nervous system, with symptoms such as headache, dizziness, nausea and vomiting. Effects may vary depending on the exposure dosage. Moreover, there are growing concerns upon industrial use of both toluene- and xylene-based solvents due to their VOC (Volatile Organic Compound) content. VOCs are normally used in solvents and thinners formulation to reduce viscosity. As per EPA (Environmental Protection Agency), VOCs are defined as “any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photo-chemical reactions.”
Aside from serious health problem associated with the VOCs, they participate in photo-chemical reactions (in the presence of nitrogen oxides and sunlight) and give rise to the formation of photochemical smog and ozone when released to the atmosphere. This made VOCs a major concern in several regions especially in the state of California, which has led to the push for replacements that do not contribute to smog.
Solvide, a Safe Alternative?
As an appropriate alternative, Solvide is a green organic solvent with the scientific name Parachlorobenzotrifluoride (formula C7H4ClF3 and abbreviated as PCBTF). It is a colorless liquid with a distinct aromatic odor and considered to have negligible VOCs and therefore, it is exempt from the EPA’s stricter Clean Air Act Regulation. The reason is that in the troposphere, Solvide is transformed with an estimated half-life of 67 days by reaction with photochemically-produced hydroxyl radicals to give mainly 2-chloro-5-trifluoromethylphenol.4 which is not an environmental concern. Figure 1 shows the ozone forming potential of common solvents used in coating industry. As can be observed, Solvide (PCBTF) forms significantly lower amounts of ozone per pound emitted and thus can be regarded as a much safer alternative compared to toluene and xylenes.
Fig 1. Ozone Forming Potential of Common Coating Solvents
Solvide is a colourless, stable, non-reactive, non-corrosive, hydrophobic, low polarity solvent that boils at 139°C and the vapour has a characteristic aromatic odour (Chemical structure shown in Fig 2). Its great advantage as a solvent is its capacity to dissolve large quantities of non- and low-polarity molecules. Only 20 g of Solvide is able to dissolve 22 g of printers’ ink. Also, the solvent has a low surface tension, allowing Solvide-based inks, paints and varnish solutions to easily penetrate cracks and crevices.
Fig 2. Chemical Structure of Solvide
Solvide benefits compared to other high VOC content solvent makes it a great replacement to be used in a wide spectrum of applications including the manufacture of printing inks, cleaners, degreasing agents, aerosols, paints, adhesives, caulks, epoxies, and urethanes. Due to its exemption from the EPA’s Clean Air Act Regulation, it’s being sought as a viable option for coating companies as well. Table 1 compares physical properties of a number of industrial solvents including Solvide. As can be observed, Solvide has physical properties close to those of xylenes while posing low to no health risks. It also possesses a significantly lower vapor pressure relative to DCM or THF which makes it safer to work with.
Table 1. Physical properties of typical industrial solvents
|Vapor pressure @ at 25°C||430||162||28||8.3-8.8||8|
|Boiling point (°C)||40||60||111||140||139|
PCBTF has been adopted by the coatings industry due to its unique position among the growing list of deregulated materials as a reliable, medium boiler of good solvency for a very wide spectrum of coating resins.
Check the Safety Data Sheet for Solvide here