Analysis of flexible plate making technology

2022-09-23
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Analysis of flexible plate making technology

flexible printing, as a kind of environmental protection printing, has developed rapidly today with people's increasing awareness of environmental protection. However, the early hand carved rubber plates can no longer meet the higher printing requirements of hundreds of shoppers on the scene at this stage, such as more visualization, layering, exquisiteness and so on. In 1973, DuPont took the lead in developing Cyrel photosensitive resin flexo. This version has high elasticity, high printing resistance and high image resolution, which makes up for the shortcomings of the rubber version. Therefore, this resin version has gradually replaced the rubber version. Of course, to make high-quality printing plates, we also need high-quality plate making technicians to cooperate with high-grade flexible plate making equipment. The purpose of this paper is to discuss the flexible plate making process. Next, take KMY flexible plate making machine as an example to introduce the technical characteristics of flexible plate making machine

I. flexible plate making machine

kmy flexible plate making machine integrates four processes: exposure, plate washing, constant temperature drying and post-treatment. All production procedures are controlled by microcomputer components, with accurate data, high precision and simple operation. The functions of the device are as follows:

1 Exposure: the imported special plate making lamp tube is used as the exposure light source to ensure the stability of the light source

2. Plate washing: it adopts two-way automatic plate washing. The plate washing brush is fine and has good stiffness. It can make 1:50 line/inch dotted plate and fine lines and small text

3. Baking plate: with automatic constant temperature device, the heating is uniform and effective

4. Post processing: imported Philips debonding light tube is used to mix exposure light tube, which saves time and improves work efficiency

II. Flexo plate making process

the process flow of flexo plate making is: original → film (negative) → exposure → washing → drying → post-processing

1. Manuscript: the manuscript design suitable for flexible printing should have the following characteristics: ① more colors, but less overprint; ② It is not required to reproduce particularly small details; ③ The line is not too high, but it can achieve the design of color printing effect; ④ It can design packaging processing online

2. Film (negative film) flexographic plate making film has the following requirements: ① meet the needs of plate making, clear graphics and texts, and accurate size and specifications; ② Use frosted film; ③ Film requires the same density of four corners; ④ Use film orthography; ⑤ Measured by transmission densitometer, the white level concentration is below 10g0.06; The black spot concentration is above 10g3.5

3. Exposure: it is divided into back exposure and main exposure:

① back exposure: the supporting film of the photosensitive resin version is upward, the protective film is downward, and it is tiled in the exposure drawer for exposure. Ultraviolet light passes through the supporting film to make the photosensitive resin photosensitive and solidified. The purpose is to establish a stable base to support and connect the protruding image part, control the depth of the developing plate, and strengthen the adhesion between the supporting film and the photosensitive resin layer. The back exposure time is determined according to the required subbase thickness

② main exposure: the supporting film of the photosensitive resin plate faces down and the protective film faces up. Lay it in the exposure drawer, and first tear off the protective film once and continuously. Then stick the film film film surface on the photosensitive resin plate, lay the vacuum film on the back of the film (not the film surface) that needs to be reworked, and then turn on the vacuum pump to make the film closely adhere to the photosensitive resin layer. Ultraviolet light passes through the vacuum film and the transparent part of the film, causing the light receiving part of the photosensitive resin to produce photopolymerization reaction and produce insoluble substances. The length of the main exposure time is determined by the model of the plate and the intensity of the printing light source used. Too short exposure time will make the gradient of plate making too straight, lines bent, and small characters and dots washed away. On the contrary, too long exposure time will make the negative text paste, the handwriting become blurred, and the anti white words and anti white dots will be filled. If there are large and small characters, thick and thin lines on the same printing plate, cover them with black film and expose them separately according to the situation, and the small parts will not be lost during washing, so as to ensure the printing plate quality

4. Washing: the function is to dissolve the parts that are not exposed to light in the process of exposure in the washing solvent under the action of the brush on the washing device, so that the photosensitive resin that receives ultraviolet radiation and produces photopolymerization reaction is retained to form relief. The length of the plate washing time depends on the thickness of the printing plate and the depth of the image. If the plate washing time is too short, non photosensitive resin will be left on the plate, which will affect the depth of plate making. If the plate washing time is too long, the plate will expand too much, which will lead to the risk of deformation or separation of fine parts

5. Drying: the function is to volatilize the washing solvent that infiltrates into the printing plate to restore the printing plate to its original size and thickness. The drying temperature is generally between 50 ℃ -65 ℃. The drying time depends on the thickness of the plate and the length of the washing time. Generally, the thick plate is 2H and the thin plate is 1H. If the drying time is too long and the drying temperature is too high, the printing plate will become brittle and affect the printing. Check whether the digital circuit voltage is + 5V? If there is no life. If the drying temperature is too low, the drying time will be prolonged. If the drying time is too short, the printing process will appear rotten plate phenomenon

6. Post processing: that is, debonding and post exposure. The main purpose is to completely harden (polymerize) the photosensitive resin of the printing plate to reach the due hardness standard, eliminate the viscosity of the printing plate, and make the printing plate surface have a good ink transmission effect. Most of the time after treatment, rats are likely to come from the vicinity. The purpose is not to crack or stick

the above introduces KMY type flexible plate making equipment and plate making process flow. With the rapid development of printing technology, our factory will keep pace with the times, continue to develop better flexible plate making equipment, and provide users with the best service

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