The gravure printing machine is a device that uses gravure printing. It is generally used for color printing of plastic films, but it has not been reported for paper printing glue. After the paper is printed with hot sol, it can be used for packaging of various medical products. Therefore, the gravure printing machine is used The gluing used for paper products is an innovation, and it is an initiative for enterprises to use original equipment for technological innovation and development of new products. Through such technological innovations, enterprises have saved a lot of equipment purchase costs and increased the utilization rate of original equipment.
1 Gravure offset control system
The system in which the equipment itself affects the distribution of the printing paste has the following parts:
1.1 Rubber roller-wire roller-scraper-rubber tank system.
This system determines the coating amount of glue, and ensures that the glue is distributed at a certain density to assist the surface of the adhesive paper. The coating state of the glue is mainly determined by this system.
1.2 Design of glue tank:
The design of the glue tank plays an important role in the printing process, because there is a process for the melting of hot sol. That is: heating-melting-aging (yellow and black appear). Therefore, in order to melt the hot sol better, the glue tank must have a certain heat capacity to keep the glue tank at a constant temperature for a long time, and the temperature in the glue tank is consistent throughout. In view of this, the design requires the glue tank wall to be relatively Thick, there must be a rib in the middle of the groove to facilitate heat conduction, the width and depth of the glue groove should be determined according to the width of the printing paper and the diameter of the screen roller.
1.3 Blowing: The room temperature and ventilation conditions affect the curing rate of the glue. Using the advantages of several sets of blowing in the printing press, one or two sets of blowing can be used to accelerate the curing of the glue.
1.4 Rewinding: Be sure to lay a good foundation at the beginning of rewinding and stick the core firmly.
2 Raw materials
2.1 Hot sol: Generally speaking, general hot sol can be used. The melting point of the hot sol produced by different manufacturers is different, and some are quite different. In order to ensure excellent coating state, it should be carefully identified before use.
2.2 Polyethylene wax: mainly used to control the firmness of bonding. Its proportion determines the quality of the packaging. Its selection must also ensure the quality, pay attention not to bring refractory crystal points, impurities, etc. In addition, it is necessary to consider its compatibility with the hot sol. If it forms a thinner layer of liquid after dissolution, it should be stirred more and mixed before use. Otherwise, the paper printed on the paper is wax instead of glue, so it cannot be used in the next step. Produced.
2.3 Adhesive paper: The choice of paper is based on the user's requirements. The second is to pay attention to the tension of the paper. Otherwise, it is a common phenomenon in the process of offset printing. Generally speaking, the tensile strength of paper is far less than that of various plastic films; such as OPP, PET, NY, etc. Therefore, the start of the drive must be stable, slow, and uniform. Suddenly fast and sudden stops will cause paper breakage and cause a lot of waste. On the other hand, the force of the paper roll on each guide roller must be consistent in direction and size, otherwise it will break. Stopping may sometimes cause the test driver to lose confidence in the trial. Another problem is the storage time of the paper. Generally speaking, it should not exceed one year. Otherwise, the whiteness and toughness of the paper will be greatly affected. This must be paid attention to. , It is best to buy and use.
3 Process factors
3.1 Matching of mixed glue and screen roller: In order to make the amount of offset printing on the paper and the screen line clear, it is necessary to take different screen rollers into account for different amounts of glue, which is often negligent. Generally, the following working principles can be followed. The larger the amount of glue, the less the wire of the screen roller used; the smaller the amount of glue, the more the wire of the screen roller used. Generally manufacturers can prepare three sets of wire rollers. That is, a set of 80 lines is used for the largest bonding fastness, and its coating amount is also the largest. A set of 100 to 120 lines is used for moderate bonding fastness, and a set of 130 to 150 lines is used for ordinary bonding. Degree of lesser products. In addition, the rubber roller and the wire roller must be parallel and have a certain pressure when working. Otherwise, there will be a partial lack of network cable, and there is not much rubber transfer. The other is the diameter and width of the network roller and rubber roller are also factors that should be considered. However, it does not make more rubber rollers and wire rollers, which causes unnecessary waste.
3.2 Rubber roller hardness adjustment: The rubber roller in the system provides a certain pressure to force the rubber to squeeze out from the mesh and disperse on the surface of the rubber paper. The hardness of the rubber roller has a great influence on the dispersion of the rubber. It is worth noting that there are two aspects. First, the hardness of domestic rubber rollers is generally not high, and there is a certain difference in hardness of products from different manufacturers. Second, the elasticity of rubber rollers will decrease with the use of time. The hardness of the rubber roller determines the amount of rubber transferred. It is necessary to select a suitable soft and hard rubber roller to make the rubber mesh line printed on the paper clear.
3.3 Cleaning of the system: due to the characteristics of the hot sol: heating, melting, cooling and solidification. Therefore, we must pay attention to the cleaning of the printing glue system. Various guide rollers, blower outlets, and both ends of the screen roller, especially when the paper is broken in the glue tank, will bring a lot of glue to the system. If the cleaning is not clean, it will directly cause Phenomenon such as paper being crushed, vacant and not glued.
3.4 Precautions for driving: The amount of glue must be calculated before driving. If you continue to drive, you must preheat the prepared glue in advance and pour it into the glue tank in a molten state. After one to two hours of constant temperature, the wax will melt after inspection Start driving when it is even. Secondly, because the temperature of the plate roller is not immersed in the rubber tank, its temperature is low, and it cannot be driven. The plate roller should be immersed in the rubber tank and run for 10 to 20 minutes. When driving, the glue should be liquid. When driving, straighten the roll paper so that the direction of the force is the same and the size is the same, so as to avoid the paper from being broken.
4 Workshop environment
Dust: Dust in the air of the workshop will adhere to the paper, destroying the firmness of the glue, especially at the air outlet, the strong airflow will sandwich the dust particles and spread the paper glue, which will affect the quality of the product. Therefore, in addition to maintaining the cleanliness of the workshop frequently, the filter screen at the air outlet should be frequently cleaned and replaced.
Above we discussed the factors that affect the printing glue and some methods to improve the printing effect. The normal production process is more complicated. When analyzing a certain quality problem, it needs more comprehensive consideration.
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