Methylene chloride (also known as dichloromethane) is an organic halogen compound with the molecular formula of CH2Cl2. It is colourless liquid with a distinctive chloroform odour that is widely used as a solvent in paint strippers and degreasing. This product is a non-flammable liquid, having no measurable flashpoint or flammable limits in air. It is miscible with most organic solvents but only slightly miscible in water.
Methylene chloride was first prepared by Henri Victor Regnault who isolated a mixture of chloromethane and chlorine that had been exposed to sunlight. It is now commercially produced by treating either methyl chloride or methane at elevated temperatures of over 400° C. These products then undergo a progressive chlorination which produces a mixture of by-products which are further separated out via distillation to produce methylene chloride.
Storage and distribution
A chemical wholesaler would have a bulk petrochemical storage facility to regulate this product. Storage is normally in a cool, dry and well ventilated facility away from oxidising agents. Solvents such as methylene chloride should be stored in drummed containers such as Isotanks made of stainless steel, aluminium or carbon steel.
A bulk solvent distributor would normally transport this solvent in bulk vessels or tank trucks. For transportation purposes, methylene chloride is classed as a flammable liquid with a fire hazard rating of 2. A full bulk chemical distributor would export the solvent throughout regions such as the UK, Europe, Africa and America. This product is a packing group 3.
Methylene chloride is predominantly used as a solvent for paint stripper, varnish removal, aerosol spray repellent and degreasing. It is an effective solvent because of its highly volatility and stability. It is also used in the processing of plastics, extracting fats and oils from food products. For example, it can be used to decaffeinate coffee/tea and to prepare hops. Methylene chloride can weld certain plastics and is therefore used in the model-making industry. One final example of its use is in the garment printing industry for the removal of heat-sealed transfers. The main user end markets are the paints, varnish, plastics, cosmetics and textiles industries.