Detailed list of offset printing defects caused by offset printing material problems

Offset materials mainly include paper, ink, printing plates, blankets and cushions. A variety of materials to meet the requirements of offset printability characteristics, otherwise there will be a variety of printing trouble.

1. Paper factor

The physical and chemical properties and technical indexes of paper, including physical performance indexes, optical performance indexes, printing performance indexes, chemical performance indexes, etc. Among them are closely related to the suitability of offset printing: tightness, tensile strength, stretchability, whiteness, absorbency, smoothness, gloss, pH, etc.

The paper's tightness and anti-brush strength value, when the pressure is separated during the printing process, the viscosity of the ink and the adhesive force generated by the moisture on the surface of the blanket will cause hair loss and powder loss, causing burr-like spots or solid spots on the printed product Failure to spend money.

The stretchability of the paper is related to the direction of the fiber arrangement. The stretch rate in the filament (sin) direction is less than the stretch rate in both directions of the fiber arrangement. Therefore, offset printing is usually used for printing on paper with the filament direction parallel to the cylinder axis to minimize Image overprint caused by wet elongation of paper is not accurate.

The whiteness and smoothness of the paper are related to the vividness and saturation of the printed image. After the paper with high whiteness is printed with color ink, the light projected on the paper is absorbed less by the paper and reflected more, so it can Better present the original appearance of ink color. The paper with poor whiteness has a member, which absorbs more projection light and reflects less light, and the printed image is gray. The surface of the paper with poor smoothness is rough, strong in oil absorption, dull after the print is dried, the projected light is absorbed more, and the reflected light is diffusely reflected, the visual effect of the printed matter is poor, and the color is dark and not bright.

Before the blotting has dried the conjunctiva, the oil-absorbent paper absorbs a large amount of the binding material in the blotting ink, resulting in a rough conjunctiva on the surface of the blot, and the product is not tarnished. When it is serious, it will also produce a pulverization failure.

Generally, the pH value of paper is slightly acidic above 5.5. When the pH value drops below 5.5, the acidity of the paper increases. This paper can destroy the dryness of the ink and cause the printing to dry.

Second, the ink factor

The ink used to express the image and color of the image is a kind of plastic fluidity, which is transmitted through the ink roller, coated on the graphics on the printing plate, used by the blanket, and finally transferred to the paper surface, after drying the conjunctiva Later it becomes solid. The main indicators of ink printing suitability for offset printing are: fixability, dryness, coloring rate, fineness, viscosity, fluidity, and acid resistance, alkali resistance, water resistance, light resistance and other resistance.

About us:

Liyang Paper Products Co., ltd is a factory and trade company located in Dongguan, China. Specialized in producing gift paper packaging, such as gift box,paper box, paper bag, book printing, notebook, folder, jewelry boxes, paper tags, jewelry tags,sticker,envelope, etc.
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