Influence of performance defects of the hottest pa

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Influence of paper performance defects on printing quality

paper is a general term for paper and paperboard, which is composed of plant fibers, fillers, pigments, glues, etc. In the process of packaging and printing, to ensure the quality of printed products, we should have five factors: human, machine, material, method and environment. Then, as one of the five factors - the main material in the material, what impact does the paper quality problem have on printing

I. smoothness of paper 1. The impact of poor preparation before installation on printing

smoothness refers to the flatness of the paper surface, which depends on the morphology of the paper surface and reflects the surface structural characteristics of the paper. In order to obtain good printing product quality, the smoothness of paper is a necessary condition. During the printing process, the degree of contact between the paper surface and the inked blanket surface affects whether the ink transfer is comprehensive and whether the graphics and texts are clear. First, due to the poor smoothness of the paper, it affects the ink demand of the paper, so that the thickness of the ink film on the blanket is different, which will increase the uneven ink color of the print, resulting in the enlargement of the graphic points of the print and the increase of the mechanical points. Second, due to the poor smoothness of the paper, it affects the ink uniformity of the paper, resulting in the printing products with blurred graphics and text, and serious point loss

second, the influence of the compression deformation characteristics of paper on printing

for printing paper, it should not only have good compression deformation, but also be suitable for multiple chromatic printing. It has the characteristics of rapid recovery at the moment of pressure removal. This is because in the printing process, the paper is deformed under the printing pressure, which can produce a buffer effect, and the paper can be in good contact with the rubber drum, so that the ink can be transferred evenly. If the printing paper used only has a high compression rate, but does not have a high elastic recovery rate, in multicolor printing, it cannot recover quickly after repeated compression deformation, making the paper larger or shrink, which will seriously affect the overprint quality of printing products

III. The Influence of poor surface strength of paper on printing

surface strength refers to the bonding strength between the surface fibers, adhesives, fillers or coating particles on the surface of paper, as well as between the coating and the paper base. In the process of printing, if the surface degree of the printed paper is poor, the surface of the paper is separated from the inked blanket, and the separation force of the ink is greater than the binding force between the particles on the surface of the paper, white edges, false printing, false printing and other phenomena will be seen on the edges of the text and text of the printed matter, which is the galling phenomenon in printing, and the impact on printing mainly has two aspects:

1 Cause pollution in the graphic part of the scope of application. Mainly reflected in: ① white spots caused by not being stained with ink after paper particles peel off. ② It is caused by the roughening of paper powder or fine paint

2. The increase of cleaning times of blanket and ink roller in offset printing. Due to the poor surface degree of the paper, it is very easy to drop materials and powder, and the cleaning times of the blanket are significantly increased, which greatly affects the printing production

IV. the impact of paper acidity and alkalinity on printing

in the printing process, the normal pH value of fountain solution is 4.8~5.2. Due to the different acidity and alkalinity of the paper used for printing, there will be different phenomena of handing over to the Netherlands Institute of sustainable packaging, which will have different effects on Printing. The acidity of the paper will cause the corrosion and sticking of the printing plate, which will directly affect the oxidation and conjunctiva drying of the imprint. It can be seen from the results of printing different papers at ordinary times that the greater the acidity, the faster the drying speed of the ink. This is because the acidic paper will absorb the desiccant in the ink, thus inhibiting the oxidation and conjunctival effect of imprinting. On the contrary, if the paper is alkaline, the alkaline substances in the paper will be transferred to the water tank and neutralized with the fountain solution in the water tank, which will directly affect the control of pH value, thus emulsifying the ink, resulting in dirty parts of the printed products and affecting the product quality. (sensor: accept the information of physical or chemical variables (input variables)

because the paper has a great impact on printing, when the used printing paper is out of the warehouse, it is necessary to strictly check the smoothness, compression deformation characteristics, surface strength, acidity and alkalinity of the paper, so as to avoid affecting the quality of printing products due to the quality of printing paper

source: Greater China Printing

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