In the offset printing process due to paper sizing porosity structure, smoothness, absorbent, viscoelasticity, and so on, paper in papermaking filler, rubber, pigment particles in the process of rough, the appearance quality of paper dust, spots, fiber ball, sand and other aspects of poor quality, often produces heap version of the fault.Heap version of the reason mainly has: depilate paper, paper powder, rubber cloth on the pile of paper wool, powder.Paper heap version for different reasons, the solution is also different.
A, hair removal heap version of paper
MAO appeared in the process of offset printing paper heap version of the fault, mainly is the result of the paper surface fiber structure loose paper hair removal, this kind of phenomenon is mainly poor printing quality of paper, the failure surface for imprinting for disorderly like confetti of grey ink surface phenomenon, paper hair off cause paper plate, rubber cloth surface covered with hair, serious when need to scrub every printed 1000 copies of plate and rubber, that cause printing quality problem, delay production schedule and time of delivery.
Paper both the hair removal is the technical problems in the process of paper making raw material and paper, offset printing is the use of intermediate elastomer indirect printing rubber roller, plate will be by transfer to the rubber roller, rubber roller on the impression cylinder under the action of a transfer to the printing paper printing process, in the process of offset printing paper would be transferred from the surface of the rubber blanket to MAO plate, along with the increase of the number printed in the paper on the surface of the plate will accumulate if MAO, cause wool pile of paper version of the fault, the paper and stick on the plate by MAO molecularly imprinted on the surface, thus affect the printing quality.
Paper fiber paper and powder both water imbibition, and oil absorption, after the paper plate by adsorption on the hair, as the plate cylinder transfer printing, wet it first encounter water roller, water roller on the plate at the same time there is a certain pressure, paper wool after wetting water roller and pressure, most tiejin on plate picture and text, and then by the ink roller ink.At this time, the paper after wetting the hair with oil resistance, although the four ink forme roller inking and cannot absorb ink, transfer to rubber cloth embossed will present a white phenomenon.
Solution:
Grasp the ink balance (1) when the offset printing, on the premise of cloth dirty version, reduce layout of water and reduce water roll in the pressure plate layout.Purpose is to make paper plate on the surface of the hair to minimize wetting, so as to reduce paper wool grease resistance and increase the inking, and try not to make it close to on the page.
(2) increase the mobility of ink, viscosity, add a small amount of ink oil, use less ink printed products, and increase the inking roller in the plate on the surface of the pressure, the purpose of which is on the plate on the hair after inking roller ink, paper to paper the mullahs, passed to the ink roller, above the main accumulating on the string of ink roller.
In addition, adjust the ink printing adaptability, add oil ink, auxiliary materials to stir well again and again.Also can appropriately increase the lose of ink of the ink fountain to solve the problem.
Second, the paper off powder heap version:
Paper surface causes heap version of honeycomb off powder all over the sky star, packing, rubber, pigment is numerous, auxiliary material loss caused by serious affect the printing quality of the products, printed about 1000 copies will need to scrub a plate, the cause of formation and paper paper heap version similar to MAO, however, there are differences in solution.Paper and powder proportion, MAO MAO large area light weight, very fine powder and heavier.
Solution: increase the mobility of ink, the ink in the appropriate adding a thin ink oil, increased ink viscosity and lose of ink, the ink roller ink storage quantity increase, make print ink, in addition, can increase the thickness of the pad of paper under the plate to increase printing pressure.
Third, rubber paper pile of hair on the cloth
Powder reasons: oil paper mainly in the manufacturing process may occur in the process of printing paper powder, wool, blanket and accumulation in the above, affect imprinting site, graphic right transfer of ink, paper, powder, would be through the rubber powder, the plate cylinder, through the ink roll into ink fountain slot, which affect the ink transfer of the road, encountered the paper off powder, paper, printing at the end of the ink fountain filled with powder, paper wool, paper powder, at this time at maximum ink quantity, imprinted ink also appears pale grinning, printed on 1000 pieces of white paper stick on the rubber cloth, rubber cloth is need to swab.
Solution:
(1) frequently wash rubber cloth.
(2) before the formal printing paper, overprint a white oil and water, make up for the shortage of the paper off powder wool (white oil is a white translucent emulsion, and use it to dilute ink, can reduce the ink viscosity, uniform color. By stearic acid, magnesium carbonate, water, dry vegetable oil, etc, is mainly used in the set of white oil, reduce the paper off powder, hair phenomenon.
(3) in the printing ink to add a small amount of adhesive, square smoothness good coated paper don't join in, don't too much, no more than 3%.
(4) in the rubber cylinder increased by 0.05 mm thick pad of paper, or adjusting the center distance to increase the printing pressure
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