1. Field of the Invention
The present invention relates to a fountain solution for use in offset printing, and more particularly, to a fountain solution which is utilized with various conventional dampening systems, and wherein the fountain solution, when properly employed, is operable to wet the non-print areas of a printing plate thereby facilitating the offset printing process.
2. Description of the Prior Art
The prior art is replete with examples of unpatented fountain solutions which are utilized in offset printing. As should be understood, the most popular of the four major printing processes, lithography, employs a process whereby the image, and non-printing areas of a printing plate are essentially on the same plane of a thin, metal plate. The distinction between the image and the non-printing areas is maintained chemically. In particular, there are two basic differences between offset lithography and other processes, they are, (1) it is based on the principle that grease and water do not mix, and (2) ink is offset first from the metal plate to a rubber blanket, and then from the blanket to the target substrate.
As will be appreciated, when a printing plate is manufactured for use in offset printing, the image area of the plate is rendered ink receptive, and water repellant, and the non-print or non-image areas are rendered water receptive, and ink repellant. On the printing press, the printing plate is mounted on the plate cylinder, which, as it rotates, comes into contact successively with rollers which have been rendered wet by a dampening, or fountain solution, and rollers which have been wet by an ink solution. The fountain, or dampening solution, wets the non-print areas of the plate and prevents the ink from wetting these areas. The ink solution, in contrast, wets the image areas, which is then transferred to the intermediate blanket cylinder. The paper or target substrate then picks up the image as it passes between the blanket cylinder and an adjacent impression cylinder which presses the paper or target substrate against the blanket cylinder.
A conventional dampening system which applies a fountain solution to the printing press normally transfers the dampening solution directly to the printing plate. For example, in the Dahlgren type of direct-feed dampening system, the fountain solution which contains up to 25% alcohol, is metered to the plate through the inking system, or can be applied, alternatively, directly to the plate as in other systems. In general, this type of dampening system uses less water and reduces paper waste at start-up of the press. In view of the cost of isopropyl alcohol, and the potential health hazards attendant its use, a number of new fountain solutions have been developed to reduce or replace alcohol in these types of dampening systems.
While the prior art dampening systems have operated with some degree of success, they have a multiplicity of drawbacks which have detracted from their usefulness. As noted above, various prior art dampening systems have utilized alcohol in combination with water in order to render the water operable to "wet out" the non-printing areas of a plate, thereby causing these areas of the plate to repel the oil-based ink. In view of the health hazards, and other deficiencies, noted above, in utilizing isopropyl alcohol, printers began using glycol ethers. In this regard, the glycol ether of choice was butyl cellosolve, that is, ethylene glycol monobutyl ether. However, and while this glycol ether worked with some degree of success, it was undesirable inasmuch as it was considered to be in a class with other chemicals which were considered to be carcinogenic.
In view of the health hazards, and the harmful environmental effects of employing chemicals which are considered VOC's, and which are now otherwise prohibited or regulated by various state and federal laws, such as California Proposition 65, those skilled in the art have looked for new fountain solutions which do not have the attendant detrimental characteristics of the prior art fountain solutions but which have approximately the same or superior performance parameters.
Therefore, it has long been known that it would be desireable to have an improved fountain solution which has particular utility when utilized to wet the non-print areas of a printing plate for purposes of repelling oil-based inks, and which further can be readily substituted for the prior art fountain solutions utilized heretofore, the fountain solution of the present invention avoiding the shortcomings of the prior art which includes numerous health hazards, and the use of volatile organic compounds (VOC's), which have been otherwise restricted, or prohibited by public law.
USPTO Backgrounds
USPTO Backgrounds