Automatic blanket cleaning systems are preferred for cleaning ink build-up, paper lint, and other debris from the blanket of an offset printing press. Automatic cleaning usually occurs when a splice is passing through a press during a paster cycler that occurs on supply roll changes, and the press does not have to be stopped for automatic cleaning. Cleaning solution is sprayed on the blanket during the splice or paster cycle, and portions of the web preceding and trailing the splice are used to blot up and remove blanket soil. This part of the web is discarded anyway, so that automatic cleaning does not slow down the press or waste any paper.
Although automatic cleaning is much more desirable than manual cleaning, because of speed, efficiency, and safety, automatic cleaning has not yet been perfected; and better cleaning results are still being sought from automatic cleaning systems.
An automatic blanket wash system described in U.S. Pat. No. 4,686,902 uses an aqueous washing emulsion that is intended for use at low concentrations of the water insoluble phase. At higher concentrations that are preferred when printing is done on high quality coated paper, the emulsion is highly viscous and difficult to handle for the rapid cleaning that is required.
Our invention provides a blanket cleaning formula that achieves optimum cleaning rapidly and effectively. Although our cleaning medium can be used to wash the blanket manually, it has been designed and formulated to be dispensed at high concentrations of the water insoluble phase through an automatic blanket washing system. This permits the preferred cleaning "on-the-fly" while the press is operating, to reduce press shutdowns and work stoppages. In doing this, our cleaner uses chemicals that are effective and convenient to handle and that achieve excellent overall cleaning performance. Further, our invention permits cleaning to be accomplished with quantities of cleaning medium that are able to maintain low solvent vapor concentrations in presses equipped with dryers.