How much is the packaging offset? (148-152)

148. What factors affect the quality of paper cutting?

1 paper stack height. As the height of the paper stack increases, the error in cutting size increases, and the cut paper stack tends to have a phenomenon that the length of the upper portion is long and the size of the lower portion is short. The stack height should not exceed 10cm.
2 How to load paper. The thickness of the paperboard is relatively large. In the process of loading the paper in batches to the cutting machine, the surface layer of the paper edge tends to tear and curl in the paper stack, and the blanket is crushed during printing.

If paper is loaded according to the method shown in Fig. 1, it may cause the A side of the paper stack under the paper stack to tear. Pay attention to raising the upper stack of paper during production, and do not allow the upper and lower stacks to touch on the A side.

If paper is loaded according to the method shown in Fig. 2, it may cause the back of the B side of the upper stack to tear. The contact on the B side is unavoidable. When you pay attention to the batch loading of the paper on the paper cutting machine, do not load too much after the first batch except for the first batch. Because the thicker the paper stack above, the greater the friction on the B-side, the easier the edge tears.
3 The sharpness of the knife. The knife is not sharp, the edge of the cut paper is not clean, the precision of cutting is reduced, and the paper edge of the incision is sticky, which affects the printing production. Since the paper used in offset offset printing is mostly hard paper such as coated paper, whiteboard paper, and kraft paper, a high-quality cutter should be used, and the angle of sharpening can be controlled to be slightly larger.

4 pressure on the paper press. The paper press must have sufficient pressure to press the paper along the cutting line so that the paper is straightened by the knife.

5 Cutter status. The work surface of the paper feeder should be parallel to the cutting line to ensure that the cut paper is rectangular and meets the needs of precise positioning during printing.

149. How to match the spot color ink according to the printing chromatogram?

Each color patch in the chromatogram is marked with the percentage of the primary dot, and the percentage of the remaining white area of ​​each primary color is used as the proportion of the white ink to mix the primary ink and the white ink of each color. If you want to call out the color code marked with 40% blue ink, then mix the blue ink and white ink with the ratio of 40%:60%, ie 2:3; if you want to call out the chromatogram, mark 40% green, 40% The pale greenish-yellow pieces of yellow are mixed in a ratio of 40%:40%:[(100%-40%)+(100%-40%)], that is, 1:1:3.

Because it is based on the principle of subtractive color mixing pigment, so the formulated ink has a lower color brightness and higher saturation; while the chromatographic color block uses the subtractive color principle of color materials and the additive color of shade. Principle, its color is relatively high degree of description, low saturation. Therefore, it is unavoidable that there is a difference in the colors of the prepared spot colors and chromatograms. The two can only be as similar as possible.

150. How to use color-toned hybrid chromatography to match spot color inks?

PANTONE CHROMATOGRAPHY chromatograms first defined a PANTONE Basic Color, which includes Yellow, Yellow 021, Warm Red 032, Rubine Red, Rhodamine Red, Purple, Violet, Blue 072, Reflex Blue, Process Blue, Green, There are 14 such as Black. Many ink manufacturers in the world produce basic color inks according to the 14 basic colors. The other color patches of the color-toned mixed color chromatography are formed by mixing these 14 inks with white ink. Each color block on the chromatogram is marked with the color below. The number and mix gives the percentage of each basic color ink required for that color. If you want to match a spot color ink according to a color sample, you first need to find the color block that matches or most resembles the color sample on the PTZ color spectrum. Or according to the customer's or designer's direct designation of the Pantone color code number, each color ink is mixed with the percentage of each basic color ink marked by the color block corresponding to the number.

Due to the great difference in the color rendering effect of ink on coated paper and non-coated paper, color-toned color mixing chromatography is divided into coated paper part and non-coated paper part, and denoted by C and U on color labels, respectively. . When the spot color ink is used for image copying of coated paper or non-coated paper, the corresponding chromatogram should be selected separately.

151. What should pay attention to when choosing ink?

1 Make full use of original ink. As long as there is the original stereotyped ink, do not use other color inks to deploy. For example, the basic color of color-toned color mixing chromatography, the domestic red ink, green, etc.

2 Try to use the ink with the hue closest to the requirements as much as possible to minimize the number of mixed inks. Since the color mixing of the ink follows the principle of subtractive color, the larger the hue difference of the ink to be mixed and the more the number of species to be mixed, the darker the color after the mixing; due to the mutual influence between the colors of the ink, the more varieties are mixed, the more the color effect is grasped. Difficulty, the more difficult it is to adjust the ink. If a certain green color is slightly yellower than the original green ink, the method of using green ink as the main ingredient and adding a little yellow ink should be used instead of mixing the similar amounts of blue ink and yellow ink.

3 The deployment of light-colored ink should use proper diluting agent.

152. What kind of diluent? How to choose the right diluent?

Dilute agents include white ink, dilute agent, dimensional oil, bright light paste and so on.

1 From the perspective of transparency. The white ink has poor transparency and hiding power. The other three diluting agents have good transparency. If the color and texture of the paper are poor, white ink as a diluting agent will help cover the background of the paper. If the prepared light color is to be overprinted on other colors, the latter 3 transparent diluting agents should be used. For example, in the packaging design, there are often light-colored backgrounds and dark-colored trademarks and texts. If the background color and the trademark are printed in a superimposed manner, and the small-area logos and texts are printed on the color sequence and printed on the background, the background color is light. Color ink must use a transparent thinner; if the background color and trademark use trapping, or first print the background after the trademark, you can use white ink to match the light-colored ink, but this process is more difficult to register and anti-color enamel dirty.

2 from the perspective of color effect. White ink used as a dilute agent formulated light-colored hair powder, ink than fresh; with Victoria oil, light dip agent, bright light as a dilute agent to obtain a light-colored transparent, ink is not clear. The poor gloss of Vine oil, lightening agent and bright gloss gloss, can enhance the luster of the ink film.

3 From the standpoint of print drying. Weili oil is made of a mixture of aluminum hydroxide and polymeric dry vegetable oil. Aluminum hydroxide has an adsorption effect on the driers in the ink, and the linking material used is a grease type. Therefore, the use of virgin oil as a diluting agent will reduce the imprinting effect. Drying speed.

4 from the perspective of post-press processing. Some poor quality white ink pigment particles are coarse and poorly combined with the binder. After printing, the binder is easily absorbed by the paper. The pigment particles float on the surface of the paper and become pulverized, which is unfavorable for the adhesion of the coating. When the anodized aluminum is hot stamped, It is also prone to pullback. Therefore, for the products that are to be filmed and anodized by hot stamping after printing, good quality white ink should be used, and the white ink content should not exceed 60%. The strength of aluminum hydroxide contained in Dimensional Oil is small, and it is easy to float on paper after printing, which is unfavorable to the adhesion of the film. The light-colored ink coating prepared by using a bright paste or a lighter remover has a good effect, but both the bright paste and the light-reducing agent contain a wax material, which is unfavorable for hot stamping of anodized aluminum, and the hot stamping is not easy or the hot stamping is not firm. phenomenon.

Printing Technology - Packaging Printing