Abstract:
Excellent development of photosensitive coatings on planographic printing plates is achieved by directing a dynamic flow of fresh alkaline developer solution that impinges on a target area of the coating extending the width of the plate and floods the target area with a turbulent flow. At sufficient volumetric flow rate, the developer solution at the target area is constantly displaced during the development time, whereby no boundary layer forms on and travels with the plate during the development time and thus the target area is always in contact with fresh developer solution.
Abstract:
A negative-working lithographic printing plate has a coating which is imaged by heating an area of the coating with an infrared laser and actinically reacting the coating in the heated area with ultraviolet or visible radiation. The coating contains an infrared absorber but the coating is not imageable by infrared radiation or by the heat generated. The imaging time is reduced since the actinic reaction rate is increased at the elevated temperature.
Abstract:
A lithographic printing plate substrate web is brush grained with some of the brushes having the bristles moving over the web along a first track and some additional brushes having the bristles moving over the web along a second track at an angle of at least 5° to the first track. Some of the brushes may have the axis of rotation perpendicular to the direction of movement of the web in the conventional manner and at least one additional brush having the axis of rotation at an angle to the direction of movement of the web. There may be a plurality of such additional brushes, usually two, with the additional brushes being angled with respect to each other. In one embodiment, the bristles of the additional brush track over the web in a direction perpendicular to the web movement.
Abstract:
A metal substrate is treated with a plurality of rotating brushes and a slurry of particulate material such that the treated surface is capable of absorbing incident infrared laser radiation. The substrate is itself capable of being visibly imaged by selective writing with an infrared laser. The substrate is coated with an ablatable coating which is transparent to the imaging infrared laser radiation. Selective exposure to infrared laser radiation ablates this coating in the laser exposed areas as a result of the absorption of infrared radiation by the substrate. The substrate can be anodized after rotary brush graining and still retain its ability to be imaged and ablate a coating. The coated article can be imaged in a computer-to-plate infrared laser imaging device. Depending on the specific coating and substrate selection, the imaged article can be used in a conventional lithographic printing process or in a dryographic printing process.
Abstract:
A catalyst structure is formed by forging catalytic particles from a slurry into the surface of a metal substrate such that the particles protrude from the surface and are permanently fixed into the surface. The forging is accomplished by engaging rollers with the surface as it passes through the slurry to press the particles into the surface. The rollers may be brush rollers, fabric rollers or solid rollers. The particles may be any particles which have catalytic activity for a particular purpose and which are hard enough to forge into the metal substrate.
Abstract:
A positive-working, infrared imageable coating and a lithographic printing plate or other element with the coating are described. The coating is a phenolic resin containing an o-diazonaphthoquinone derivative which couples or reacts with the resin to partially insolubilize the coating and an infrared absorbing dye or pigment which further insolubilizes the coating and which renders the coating imageable by infrared radiation. The coating contains only that quantity of infrared radiation absorber necessary to be imageable and only that small quantity of o-diazonaphthoquinone derivative necessary to supplement the insolubilizing function of the absorber. Specifically, the absorber is from 1 to 10 weight percent of the total dry weight of the coating and the dry weight ratio of the absorber to the diazonaphthoquinone moiety is greater than 1:5 and preferably 1:2 or greater. By replacing a portion of expensive dye with some less expensive o-diazonaphthoquinone derivative to obtain the necessary degree of insolubility, the cost of the coating is greatly reduced.
Abstract:
In an offset printing apparatus, the offset blanket is configured to prevent the transfer of ink from the bare metal edges of the lithographic printing plates. These edges may also have burrs which would exacerbate the ink pick-up and transfer of the unwanted ink to the offset blanket and the paper. The offset blanket is shaved down or relieved in the areas juxtaposed to the edges of the printing plates so that the ink will not be transferred.
Abstract:
A series of printing plate imagers for imaging lithographic printing plates onto a continuous web are combined in a single imaging process line. The imageable web is passed through a series of properly spaced imaging stations in the line with multiple plate sections being selectively imaged in one or another of the stations or with each individual plate section being partially imaged in two or more stations. The imaging stations may operate in different modes, such as the digital mode with a laser and the analog mode with actinic radiation, with the prepared web capable of being imaged by either of the modes.
Abstract:
A novel method and apparatus for the imaging of a continuous web on an internal drum type imaging device is disclosed. The method and apparatus may further be included in a process to produce punched, imaged sheets. A web is punched with registration holes and imaged in an internal drum-type imager prior to cutting the web into individual imaged plates particularly for use as printing plates. The web with an imageable surface is serially punched, imaged and sheeted with the punched holes being utilized to assure registration and alignment in the imaging operation and in the subsequent use of the plates on a printing press. The imaging station has an arcuate concave imaging platen. The web is advanced under tension and then stopped while a roller on an arm forces the web down into contact with the platen. Vacuum is then used to hold the web on the imaging platen while the web is imaged.
Abstract:
The water-loving properties of an anodized aluminum lithographic surface are enhanced or restored by treatment with a solution containing a monomeric, organo-phosphonic acid chelating compound or salt thereof. Such treatment can take place following, during or in lieu of the treatment of anodized aluminum in web form with an alkali metal silicate in the process of manufacturing printing plates. Alternatively, the treatment can be carried out as a plate is developed and/or prepared for the press. In a third approach, an organo-phosphonic acid chelating compound can be incorporated into a fountain solution, ink or correction fluid.