DS Chemport (Australia) Pty Ltd was founded in 1987 and is a manufacturer and supplier of a range of chemicals used in the offset lithographic printing industry, including:
- fountain solutions
- plate cleaners and correction agents
- plate developers
- ink additives
- water-based varnishes
- specialty chemicals
DS Chemport currently supplies 60 per cent of the Australian graphics art chemicals market.
The printing process typically involves transfer of ink and fountain solution to the printing plate, via a series of rollers, and then onto the item being printed. A variety of chemicals can be added to the fountain solution to improve its effectiveness. The main function of any additive is to reduce the surface tension of the water in the fountain solution so that the non-image area of the printing plate can be covered with a thin controllable film of water. This is achieved primarily by the inclusion of alcohols or surfactants. Other additives include buffers to control the acidity, biocides to prevent mould growth and chelating agents to remove contaminants that may have dissolved from the ink or substrate.
Isopropyl alcohol (IPA) is commonly used as a fountain solution additive. It is typically added at a rate of between 5 and 20 per cent by volume to provide a 'wetter' fountain solution with increased viscosity and a greater affinity for the printing plate. The benefits of IPA include:
- increased delivery efficiency of the fountain solution;
- better wetting of the printing plate; and
- improved efficiency of the printing process.
The use of IPA has allowed an increase in printing speeds from approximately 8,000 impressions per hour up to 18,000 impressions per hour.
All of the alcohol added to the printing ink eventually evaporates into the atmosphere. Evaporation provides a benefit by assisting in the removal of excess heat generated by friction.
Problems with IPA include that as a volatile organic carbon (VOC) it contributes to the production of atmospheric photochemical smog, it is flammable (and therefore requires careful handling and storage), toxic and expensive.
Cleaner Production Initiative
A number of alternatives are available to replace alcohol in the printing solution, however they all have disadvantages:
- alternative solvents or surfactants which reduce the surface tension of the fountain solution usually result in a reduction in the delivery of fountain solution to the printing plate;
- the evaporation rate of the alternatives is usually lower than IPA, which may interfere with ink quality;
- some alternative solvents can attack the image area of the printing plate or cause swelling and distortion of the roller surface; and
- they may be considerably more toxic than IPA.
DS Chemport observed the behaviour of IPA in the printing process and realised that the same effect could be reproduced by electro-chemical means. After extensive testing in Australia and Germany, and with the assistance of the CSIRO, DS Chemport developed the lithographic alcohol eliminator (LAE), which modifies the properties of the fountain solution at a molecular level, such that it behaves as if alcohol were present.