Introduction to the new pre printing technology of

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Introduction to the new process technology of intaglio printing carton preprint (II)

-- it can be used for large-scale multicolor color printing. The maximum format of traditional color offset printing can generally reach 1.2 × 0.9m (full size sheet) and mostly four-color printing. The maximum width of the printing material of the unit gravure printing machine used for carton pre printing is 2.5m. (Shaanxi beiren printing machine company has produced various specifications of pre printing machines 1300mm, 1650mm, 1800mm, 2000mm, 2200mm, 2500mm and they are in good operation). The number of printing colors can reach the color group, and it can also print gold ink, silver ink and other special inks

-- it is more suitable for large-scale long edition printing. The pre printing plates are made of steel chrome plated engraving intaglio plates, with a printing resistance of 10000 printing times, which reduces the time of changing plates, and is especially suitable for large quantities of long plate printing

-- the corrugated box produced has higher strength. Because the production of corrugated boxes for pre printing is completed on the production line, there is a certain heating and forming time during the production, the final corrugated boxes have high strength, and can avoid the uneven gelatinization, carton reinforcement, cardboard warping and other phenomena produced during the production of veneering machine

● production equipment and process of carton pre printing

-- the main equipment used for carton pre printing is a large unit gravure printing machine, and its auxiliary equipment is corrugated paper production line computer-controlled cross cutting and longitudinal cutting. The pre printed face paper is loaded on the noodle station of the corrugated board line, and is finally made into color paperboard through the processes of sizing, veneering, flattening, drying, cutting, etc., and then the carton is made through the subsequent processing processes such as die cutting, gluing, etc

-- requirements of carton preprint on corrugated board line. The important configuration of the intaglio printing carton preprint production line is the computer crosscutting on the corrugated board production line, that is, the identification crosscutting control function must be added to the crosscutting knife of the corrugated board production line. Its main control principle is that the photoelectric eye identifies the crosscutting mark on the corrugated board printing pattern, transmits the time when the crosscutting mark reaches the photoelectric eye to the control computer, and then the control computer controls the crosscutting time, Thus, the corrugated board is accurately cut off at the boundary of the pattern. At present, cross cutting machine manufacturers at home and abroad can install this function for carton factories, and the cross cutting accuracy can be controlled within 0.5mm. At present, the corrugated board production lines currently produced in China can install computer cross cutting devices according to customer requirements

computer longitudinal cutting and computer transverse cutting are the same principle

-- ink and varnish: the inks used in the pre printed gravure printing machine are mainly alcohol soluble inks or special gravure printing inks for water-based paper

when the pre printed paper is pressed and dried on the corrugated paper production line, the ink used is required to have good high temperature resistance and friction resistance, otherwise the color surface will be scratched or dragged. At present, the "Tiens" brand ink produced by Tianjin Dongyang ink factory can meet the requirements of water-based paper gravure printing, with low cost and no pollution, and meets the national environmental protection requirements. The intaglio carton pre printing ink produced by essence industry and Trade Co., Ltd. is based on cellulose and the main solvents are alcohol and ester. Compared with water-based ink and offset printing ink, this ink has bright color, high gloss, abrasion resistance, high temperature resistance of 180 ℃ -250 ℃, good printing adaptability, clear printing patterns, delicate color performance, etc., and has excellent adhesion to most printing surfaces. In addition, the ZZ type carton preprint ink produced by Guangdong Shunde Demai ink company has good gravure printing adaptability, which is suitable for a variety of substrates from g. the large-scale field printing has good leveling, and the level transition is clear. Through the inspection of the authoritative organization its, the content of heavy metals meets the international standard, there is no harmful solvent, the ink is resistant to high temperature of 170-250 degrees, abrasion resistance of 2kg per square centimeter, and it is ground 400 times under pressure, and the bottom ink is not decolorized, The surface friction coefficient of printed matter can also be adjusted according to customer requirements to meet the handling and stacking requirements of carton manufacturers. Some domestic manufacturers of glazing oil adopt high-temperature glazing oil of American cprecision in technology company, and some domestic brands are also widely used, with good results

-- printing plate: the pre printed printing plate adopts steel chrome plated electric engraving intaglio, and the number of lines of the intaglio can reach more than 300 lines, which is completely suitable for field printing and point level printing of color transition. However, at present, in terms of improving the performance of the tape, the intaglio printed on sheet is deeper than that of the general plastic printing intaglio when engraving, and the price of intaglio plate making has been reduced from 0.7 yuan/cm2 to about 0.35 yuan/cm2, which is close to the flexible plate, The printing number of gravure plate is times that of flexo plate, which can reach ten thousand printing. The polishing roller can use a fixed line roller, which adopts shaftless transmission. At present, there are many domestic plate making manufacturers, such as Shanghai Yuncheng, Nanfang plate making, Sanmenxia Lanxue and other manufacturers, whose electric engraving has reached the international advanced level

-- paper: the substrate of gravure pre printing must use coated white paper with good surface smoothness, strong printing adaptability and stable moisture content (6%-7%). The zero point conditioning device, pendulum knife edge, imported coated ox card and domestic gray bottom white board can meet the paper matching requirements of high-grade color corrugated box face paper. Finnish M-real forestry company is famous for producing coated paper with high hygienic standards all over the world. 185g coated paper has been widely used in domestic prepress machines, and the quantitative range of paper is 150g-350g/m2. Mead paper industry in the United States has been using 500 grams of raw wood pulp to coat kraft linerboard gravure printing cartons and tinned beer portable cartons, with strength higher than corrugated cartons

● problems and solutions

the printing products of the paper concave machine include pre printed paper rolls such as decorative paper, bubble sugar paper, beer and beverage boxes, cigarette boxes, medicine boxes, milk boxes and fruit boxes, household appliances and daily necessities, which are characterized by exquisite design, bright colors and large demand. For some common problems in the application of paper concave machine, the following solutions are for reference

wrinkling: the tension of high gram pre printed paper roll is about 50kg, which is more than that of film (10kg) and thin paper (25kg). 2.7 batch experiment: it is difficult to control samples with the same parameters. When the moisture content is uneven and the thickness is uneven, greater tension changes will cause the paper to swing laterally and form the wrinkle of the print surface. The installation of preheating device on the paper concave machine helps to reduce the tension change caused by moisture loss (if the moisture is too low, install a humidifier); If the deflection adjusting and flattening roller is added, it will help the paper roll to flatten as much as possible and reduce the swing

ink embossing: in addition to the above-mentioned temperature resistant ink and varnish, the latest air cushion heating plate heat conduction control system can reduce the heating temperature and stress strength when the paperboard passes through the hot end. Why are some tensile testing machines very cheap. The process is that an air spraying channel is set at the gap between the heating plate and the paperboard, which can spray air instantly to form an air film to hold up the paperboard, so as to avoid scratches, ink drawing and other defects caused by excessive heating and pressure of the paperboard

whitening: it is mainly caused by dust on the surface of the paper roll and ink blocking. Installing dust removal and explosion-proof electrostatic ink suction devices in the field printing group can respectively blow and dust, improve the inking effect, and reduce the phenomenon of point loss

spiral winding: the gravure printing machine for preprinting shall adopt a closed-loop control system to ensure the taper control of the winding tension

uneven edge trimming: if the section edge trimming is uneven, the standby pressure roller (receiving rubber roller) can be added to drive the air out of the paper roll, so as to eliminate the surface static electricity. When the paper roll is collected and pulled, it is close to the roller device to reduce the edge trimming swing

installing the PLC computer deviation correction device also helps to alleviate the uneven edge. Another way to solve the uneven edge is offline rewinding

paper roll lapping: improper paper roll lapping during the printing process will cause downtime and slow down, and affect the consistency of prints at the same time. The paper can be connected by zero number docking without interrupting the printing process

at present, the gravure printing machine suitable for carton preprint produced by our company mainly has the following characteristics:

(1) high printing speed and high overprint accuracy

the printing speed of this series of models is m/min, and the overprint accuracy is ± 0.2mm longitudinally (automatic registration system tracking, normal printing brush) and ± 0.2mm horizontally (manual control)

(2) large printing format and good printing quality

the printing format of this series of models can be divided into the following specifications 1300mm, 1650mm, 1800mm, 2000mm, 2200mm and 2500mm, which can be matched with corrugated cardboard line

(3) printing and oiling can be completed at one time

this series of models can realize 4-10 color ink printing, and can be completed at one time with varnish. The coating unit is driven by a separate motor, and the coating roller with a diameter different from that of the printing plate roller can be used to save costs

(4) use alcohol soluble environmental protection ink or environmental protection ink printing

this series of models are equipped with an independent intelligent drying system. The fully enclosed oven and heat source can be used for secondary return air, which can fully dry and solidify the ink, and ensure that the printing surface enters the corrugated paper production line and does not fade and "pull" when rubbing with the backing plate. The automatic ink circulation system and ink stirring stick can make the printing of mass-produced prints, and the ink color is uniform without chromatic aberration

(5) high speed automatic refueling without shutdown

this series of models can realize high-speed automatic refueling without shutdown, greatly improve the yield and save working time

(6) automatic control

the whole machine of this series of models adopts closed-loop tension control system, dt950m Ⅱ photoelectric registration device (or domestic registration device) of Japan Taiyang company, static picture observation system, computer automatic receiving and refueling system, and adopts pneumatic shaftless plate loading, pneumatic scraper, imprinting, shaftless clamping, paper preheating, water cooling and other structures, making the machine operation more convenient and reliable

● conclusion: the production of cartons by pre printing is still in the ascendant in China. With the joint efforts of machinery manufacturers, ink, paper, printing plate suppliers and the majority of carton manufacturers, the grade of packaging cartons in China will be raised to a new level

source of information:

source of information: Huicong Author: sunjingzhong

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