subject: How to prevent the overlay of paper are not allowed to lead to the phenomenon of expansion - paper c [print this page] How to prevent the overlay of paper are not allowed to lead to the phenomenon of expansion - paper c
Offset lithography is the use of oil and water immiscible principle to carry out printing. So after printing the paper generally elongate, but shorter contract situation is rare, for the elimination of such failure, is to discuss the printing process.
Print Network HC Paper is a fibrous tissue with the variability of plant material, it has the function of the wet moisture release, when the air when the water is constantly changing, it will happen and air conditioning and humidity balance. When the air humidity was higher than the paper contained in the water, it will absorb moisture from the air and the expansion of elongation; the other hand will release moisture and shrink shorter, in order to achieve the relative humidity environment with a bad balance.
Lithography Offset printing The use of immiscible oil and water to carry out the principle of printing. So after printing the paper generally elongate, but shorter contract situation is rare, for the elimination of such failure, is to discuss the printing process:
1, printing horizontal wire lock as far as possible
Paper has horizontal and vertical wire lock wire lock of the points. Part of the process of papermaking in the paper, as pulp (plant fiber) is vertically mobile with the wire-line flow, fiber by the sudden acceleration, most of the movement direction along the wire connects, it formed what we call the vertical and horizontal wire lock. Paper, the plant fibers are translucent hollow tube like structures that we can image: the length of the fiber itself is what we call vertical wire lock, and fiber and fiber orientation is horizontal wire lock gap. The results show that: the cohesion of the fiber itself is greater than the binding force between the fibers (mainly hydrogen bonding). Damp paper, the longitudinal direction of the stretching wire lock wire lock than the transverse direction stretching to be small, more or less 1:2. Therefore, overlay products that must be considered more precise aspect of their paper the deformation of wire lock relationship. Therefore, in printing, making paper, wire lock the vertical direction and the roller axis parallel to, and batch printing paper with the direction of the wire lock to be consistent.
2, overprint clear water (commonly known as pressurized water)
In the printing paper is not very good grasp of the situation, in order to prevent elongation of paper in printing, you can use a clean water first overlay method to meet the printing requirements of paper and then start printing the color, the method to solve overprint allowed to a certain extent.
3, control the printing layout of water
Printed page of paper stretch of water the size of the key factors that control the layout of the water through the Blanket Passed to the paper, the greater the layout of water, the greater the stretch. Thus the layout of water as small as possible, especially when printing 80 grams of Offset special to note.
4, by pulling Edition machine stretched plate
General monochrome machine in the third, four-color printing process, two-color printing machine in the second process, the paper's image has become large, elongated, resulting in overprinting not allowed. This is because PS version Material has good ductility, can be stretched by pulling Edition machine, so that image with paper plates balanced elongation Ershi image overlay accuracy.
Currently, most small and medium enterprises, generally no air conditioning, most of the practice is to sprinkle some water around the machine to increase air humidity. Do not ask for non-network printing products, you can really connected with Pentong sprinkler edges toward the machine after printing; for workshop humidity is high, the best cut of paper covered with a plastic cover up to prevent moisture longer ; If it is drying the second printing, can be used by the version line method to compensate for shrinkage of the image of interest.
Overall, the settlement papers are not allowed to stretch the process leading to overlay approach are many, as long as the printing process of strengthening and Management Generally can be resolved.
