Prepress process of the hottest composite transfer

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With the continuous progress of science and technology, the continuous invention and innovation of printing equipment, and the improvement of process technology, the prepress process of composite and transfer line gravure is like a duck to water, and it is rising day by day. This article will briefly introduce the pre press process of compound, transfer and connection gravure

"the tide rises and the ship rises" should be appropriate for technicians in the printing industry. Good horse with good saddle, advanced equipment combined with advanced technology can achieve the desired effect, save time, labor and cost, and produce more representative packaging and printing products. It is beautiful, generous, bright and elegant, representing advanced equipment, advanced technology, advanced design and enterprise image

I. formulation of prepress process for composite and transfer

the prepress process production requirements of ordinary gravure printing machines are relatively strict, but the prepress process production of composite and transfer connecting gravure needs to be cautious. The development of prepress technology is a clear path for printing production, everything is connected and linked. No human error or predictable error is allowed in the details of each process. Once it is wrong, irreparable losses will be caused

1. Formulation of process raw and auxiliary materials

① transfer film: generally, pet base film is selected. In contrast, the tensile range of pet base film is smaller than that of OPP base film, and its stability is good

② backing paper: the selection of backing paper should refer to the sample sheet or the customer's requirements. The surface of the paper is flat and smooth, with good softness (the paper fiber should not be too hard). When the next process is die-cutting, the indentation is full, and the box type is free of burrs

③ composite adhesives: at present, the composite adhesives used in composite products in China include solvent based, water-based and UV adhesives. Their characteristics are different. Solvent based composite adhesive: it has fast drying speed, good release performance, peculiar smell, which is not conducive to environmental protection. The composite product is curled and tightly placed for a long time, and its color turns yellow. There are white cloud fog points observed under bright light (caused by the high content of rosin in various similar solvent adhesives). Water based compound glue: no solvent volatilization, non-toxic, environmental protection, especially when the base film is laminated with the paper after gluing, the glue liquid is a natural flowing liquid, which can quickly and fully fill the concave part of the paper surface, with good finish, good compound fastness, no warpage, beautiful flatness and excellent comprehensive performance. UV adhesive: the drying speed is fast, the colloid is soft, the adhesion performance is good, the bonding strength is large, the bonding effect remains unchanged after high temperature and freezing, and it does not explode color and brittleness. Composite adhesives with different properties can be selected according to different equipment performance, drying method, gluing method, product requirements, etc., so as to achieve the desired effect

④ varnish: resin oil for short, which is used to coat the gold, silver and laser paper after compounding or transfer, so that it has better adsorption on the ink surface when printing. There are two kinds of commonly used varnishes. The first is oily varnish (volatile dry type). Main ingredients: synthetic resin, nitrocellulose, acrylic resin and additives. Coating advantages: thick coating layer, fast drying speed. Disadvantages: resin inks of the same system are easily soluble in the printing process; The second kind: water-based varnish. Main ingredients: acrylic lotion, defoamer and additives. Coating advantages: less coating, thin varnish layer, cost saving, and it is not easy to dissolve with ink in the printing process. Disadvantages: non volatile resin, slow drying speed

⑤ printing ink: at present, volatile dry oily ink is used for paper gravure printing ink in China. The solvents are acetic alcohol, ethanol (isopropanol), butyl acetate and even toluene, which are harmful to human body and not conducive to environmental protection. However, the printability of water-based gravure ink is not mature, and the technology is still in the process of development. In the selection process, it should be noted that the ink system is benzene free ink, the evaporation and drying speed is neutral, and the particle fineness of ink pigment is 3-5 μ m. Good color concentration, color saturation, high temperature resistance, strong adhesion, easy to bronze, and the printing surface is not easy to scratch. Diluent: ethyl acetate, ethanol (more than 98.5% anhydrous) or isopropanol. Slow drying agent: butyl ether (less toxic)

2. pre production process analysis

① introduction to the process of composite and transfer paper

the transfer film is bonded with the backing paper with adhesive. Because the paper is breathable, the wet composite method is generally adopted. First, the film is applied with glue, then it is bonded by the embossing roller, and finally it is dried. The gluing method can be three roll gluing or corrugated roll gluing; Oven temperature and printing speed determine the drying condition of products. The quality indicators that need to be controlled include: composite fastness, surface flatness, peel integrity. Separate the base film from the paper, so that there is only inp4h-hema-tris system on the paper surface. With the increase of the content of hydrophilic monomer Tris, its oxygen permeability increases by a layer of adhesive, aluminum layer and coating layer. The quality of the stripping process largely depends on the previous processes such as the coating preparation, coating layer and composite effect of the base film. The stripping itself needs to control the tightness, uniformity and surface scratch free of the film. The stripped pet and film can be re coated and transferred again, which greatly reduces the production cost

② composite and transfer line gravure printing process

generally, the composite paper needs to undergo a 24-hour curing period, and the pet base film is transferred to the paper through the stripped aluminum layer and coating layer. However, if the length of the drying channel is 16m and the maximum temperature is 200 ℃, the ideal effect of compounding and transferring to the paper can be achieved after double cooling rollers

③ gluing roller

the use of gluing roller should be determined according to the production products. The size of glue application directly affects the product quality, composite fastness and peel integrity

④ the printing plate 960 Cerutti 3288 uses a hollow Version (a printing plate without an axis during basic processing in the plate making factory), but it has been changed to a plate with an axis (the axis is welded with the printing plate during basic processing). At present, many domestic printing enterprises have no good solutions to the problems of hollow version in the printing process. Its main disadvantages are: the plate making time is relatively long, the machining is difficult, the axis used by the plate making factory is not completely consistent with the axis of the printing factory, or the swing of the dynamic balance of the printing plate caused by long-term use and wear exceeds the specified range by more than (0.3mm), so there are obvious overprint fluctuations and other irregularities in the printing process. However, from the perspective of product quality and process producers, we should try not to use hollow version, which brings us many inconvenient factors in printing production; Although the price of the shaft version is slightly higher, it is still beneficial in terms of the output rate of finished products

the UV glazing process of intaglio continuous machine has been very mature in China to effectively regulate the degradation time and cycle of bioplastics. However, in order to achieve no defects in post press processing, we must consider carefully in the production of pre press process. Because the paper must be baked by UV lamp at high temperature during UV printing, paper deformation often occurs, which brings difficulties in registration to the post-processing of printing. Therefore, in the pre press process typesetting, we should focus on the factors that affect the post-processing, such as the accuracy of the die cutting position and the deformation rate of the paper

the following is a brief introduction to the flip products of fine cigarette packaging: 960 Cerutti 3288 gravure printing machine, the maximum printing width is expanded to 820mm, including the parameter range of combustion heat release, combustion smoke density and combustion toxicity. The requirements for the accuracy of post press bronzing, concave convex and die-cutting registration of the flip products of dry cigarette packs are high, and most of them use 18 spell (3 × 6) , add 4 mm double knives at the connection of two single knives in the horizontal row, and the spacing of six tie rods in the vertical row: 2600mm × 2450mm3, which greatly solves the problem that the paper cannot be aligned after printing due to paper deformation

new equipment, new technology, new process and re innovation are our common goals. Only with advanced and advanced technology can China's printing technology be advanced to the international leading level and take the lead in the field of high-tech printing technology in the world

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