Printing plates layer

Letterpress. This is the oldest printing process stiU in use. It continues to be replaced by newer printing processes. Printing is conducted from a raised image area of the printing plate. Inks in the printing process are transferred directly from a raised area to a substrate. The printing plates contain a thick layer of photopolymer (often a mixture with polymer such as poly(vinyl alcohol) deposited over a plastic or aluminum base. 

Fig. 15. Flexographic printing station, where the fountain pan suppHes ink to the mbber fountain roU, which in turn suppHes ink to the anilox roU. The doctor blade removes excess ink from the surface of the anilox roU so that it transfers a uniform layer of ink to the printing plate. The printing plate then...

Proofing materials have many of the same sources of variability as film, plus the added problem of registering, ie, accurately overlaying, the different colored layers. The printing plate must be exposed precisely to hold all that is discernible in the films. The accuracy of the exposure is critical because the plate must retain all the information contained in the films for faithful reproduction on the press. 

Diethanolamine salts with fluoroalkanol phosphates are used for presensitized lithographic printing plates. The plate has a partially exposed photosensitive layer containing a polyurethane resin having acidic H-containing substituent and... 

Haley, N. F. Corbiere. S. L. Method of Making a Lithographic Printing Plate Containing a Resole Resin and a Novolac Resin in the Radiation Sensitive Layer. U.S. Patent 5,372,915, December 13, 1994. 

A printing blanket with a specially manufactured layer designed to give or compress, under pressure from the printing plate and impression cylinder. Compressible blankets resist smashing and usually print a sharper halftone dot. 

The increased interest in energy sensitive polymers probably evolves from the shortcomings of the conventional image recording media-silver halide emulsion. It is both difficult and expensive to apply emulsion films as protective layers or use as printing plates or etch resists. Synthetic polymers are one to two orders of magnitude less radiation sensitive than halide emulsion, but their unique properties of chemical and physical resistance easily overcome this disadvantage, ( ., Table IV). 

Solubility modifications. The first commercial photopolymer system introduced in 1959 was the photopolymer printing plate based on the difference in solubility which results in a photo-polymerizable layer on exposure to actinic light relief Images can be obtained by washing out the unpolymerized parts. The photo-polymerizable layer consists of a binder, a monomer, and a photoinitiator. This layer is mounted on an aluminum, a steel, or a polyester support and covered by a removable polyester sheet which protects the plate before use. Before Imagewlse exposure, the... 

The photosensitive layers of early plates were composed of acrylate/methacrylate and acrylated cellulose acetate mixtures. Other printing plates contained polyamides or nylon derivatives as binders. Generally, printing plates contain a mixture of reactive monomers and multifunctional oligomers (pre-polymers), polymeric binders, and photoinitiators with exceptional cure depth. The original photoinitiators were benzoin derivatives. Later, anthraquinone and other systems were used. 

The printing plate, covered with the polymerizable material, often incorrectly referred to as the photopolymer, is irradiated through a film negative to initiate photocuring. Thereby, the areas of the photosensitive layer corresponding to the... 

Uses Photoinitiator for U V-curabie pigmented systems, esp. for thin layer applies, such as printing inks (offset, flexo, screen inks), printing plates, photoresist, solder mask, pigmented varnishes, acrylic clear varnishes Features Bifunctional compat. with resins Properties Off-wh. powd. faint char, odor sol. in most common org. soivs., monomers, prepolymers insol. in water Use Level 0.5-5%... 

Oohashi, H. Kunita, K. Method for colored image formation using discoloring material in photosensitive-thermosensitive layer on lithographic printing plate precursors. Eur. Pat. Appl. EP 1602480,2005 Chem. Abstr. 2005,144,43249. 

Konrad, K. P Elsasser, A. Fischer, R Davies, J. K. Recording material with pigmented radiation-sensitive layer for preparing printing plates. Eur. Pat. Appl. EP 1043627, 2000 Chem. Abstr. 2000, 133, 303590. 

Mack, G. Mueller, B. Jung, G. Frass, W. Developer for exposed negative-working reproduction layers and its use in preparing printing plates. Ger. Offen. DE 3439597,1986 Chem. Abstr. 1986,105, 235876. 

---