In the process of die cutting, we often meet a variety of problems, the common is the burst line and dark line, then what is the cause of the burst line and dark line, and how to solve it? Here is a small series to give you the answer. "Burst line" means that because the pressure of die cutting indentation is too large, it exceeds the endurance limit of the paper fiber, so that the paper fiber is broken or partially broken; "Dark line" refers to the undeserved indentation line, which is generally caused by inappropriate selection of die cutting plate and indentation steel line, improper adjustment of die cutting pressure, poor paper quality, inconsistent direction of paper fiber and die cutting plate row knife, low water content of paper resulting in decreased flexibility and other reasons. Solution 1.Select the appropriate die cutting plate; 2.Proper adjustment of die cutting pressure; 3.The printed matter to be die-cut is placed in the workshop for a period of time before die-cutting; 4.Improve the relative humidity of the workshop environment 5.Reduce the tension on the paper In addition, there is a special case, that is, when die-cutting the hard box cigarette pack small box, because the distance between the indentation lines in many positions is very close, if the height of the indentation steel line is configured according to the normal situation, the tension on the paper is too large during molding, it will also cause "burst line". Therefore, we should try to reduce the tension on the paper, there are two methods: one is to reduce the height of the indentation steel wire; The second is to reduce the thickness of the indentation bottom die strip, but the two can not be used at the same time, otherwise the indentation effect is not very good. The best way is to reduce the height of the indentation steel wire, the height of the reduction is usually 0.1 ~ 0.2mm, the specific according to the paper quantitative determination, quantitative in 350g/m2 above the paper need to reduce the height of the indentation steel wire is 0.2mm, quantitative in 350g/m2 below the paper should be reduced by 0.1mm.

There are many factors affecting the quality of the film, in addition to paper, ink layer, film, adhesive and so on In addition to the objective factors, it is also affected by subjective factors such as temperature, pressure, speed, and glue amount. If these factors are not handled well, various laminating quality problems will occur. There are snowflakes on the product 1.The amount of glue is too small: the amount of glue is too small, and snow spots will appear on the entire surface of the print. The amount of glue can be appropriately increased. 2.Inappropriate pressure: too much pressure on the pressure wheel will squeeze out the adhesive on the edge of the print, resulting in snowflake spots on the edge of the print; Snowflake spots can also appear if it is not compacted. The pressure can be adjusted appropriately. 3.Print powder spraying too much: print powder spraying too much, the compound appears loose pine flower white fog, encounter this situation, should be appropriate to increase the amount of glue, or in the coating before sweeping the print powder. 4.Pressure wheel pressure is too small: there are bubbles on the surface of the entire printing product because the pressure of the pressure wheel is too small, and the pressure of the pressure wheel can be appropriately increased. The coated product has wrinkles The main reasons for the wrinkling of the coated product are the imbalance of the film transmission spoke, the inconsistency of the tightness at both ends of the film or the wavy edge, the thickness of the rubber layer, or the uneven electric wheel and the rubber spoke at both ends, the pressure is inconsistent, and the linear speed is different. Measures can be taken to adjust the transfer wheel to the equilibrium state, increase the film, adjust the amount of glue and increase the temperature of the drying channel, adjust the position and process parameters of the electric heating wheel and rubber wheel, etc.

As a kind of widely used adhesive, coated adhesive has a variety of processes. Here are some of the common processes used: 1. Hot melt coating: hot melt coating is to place a layer of film on the surface of the print, and then through hot pressing the film and the print together.In this process, the laminating glue is heated to turn it into a liquid, which then forms a uniform coating between the print and the film. This method can make the surface of the printed matter smooth and bright, and has waterproof, wear-resistant, oil-proof and other properties. 2.Water-based coating: Water-based coating is an environmentally friendly coating process. It is achieved by coating a layer of water-based laminating glue, and then covering the film over the laminating glue. Because the water-based coating adhesive does not contain organic solvents, it has little pollution to the environment during use. 3.UV coating: UV coating is a coating process using ultraviolet curing technology. In this process, a layer of coated adhesive is first applied, and then ultraviolet light is used on its surface to cure the adhesive quickly. This method has the advantages of fast speed, stable quality, etc., and can also make the printed surface more durable and textured. In short, the use of coated adhesive process is mainly selected according to different application scenarios and use needs. In practical applications, we should combine materials, equipment and production process and other factors to choose the most suitable for their own film coating process to achieve the best results.

1. The effect of membrane material There are dust adsorption, particle impurities, poor plasticization and other crystal points in the film. The moisture absorption on the film surface of the material and the precipitation of additives in the material will cause composite bubbles. The thickness of the film should be as uniform as possible, if the distribution is uneven, it is easy to cause the imbalance of the compound pressure, and there will be a gap where the pressure is small, thus forming bubbles. The way to avoid these effects is to do a good job of raw material inspection and maximize the online corona at the same time of production. 2.The impact of adhesives A large amount of air was mixed in the preparation of the glue solution due to agitation and circulation, which was not discharged in time during static defoaming and was locked in the composite film to form bubbles. The correct approach is: The adhesive is prepared in strict accordance with the instructions, the main agent is added first, and then the ethyl acetate is added and stirred evenly, and then the curing agent is added while stirring, so that the curing agent is full of activity and evenly dispersed, which is conducive to affinity with the printing substrate and reduce bubbles. In addition, the prepared adhesive should be fully static and degassing, and then poured into the rubber tray for use. Moreover, when pouring glue, it is necessary to fall slowly along the edge of the glue tray, and the glue liquid in the glue tray cannot be violently stirred, so as to avoid the formation of bubbles in the composite film due to the mixture of air. The viscosity of the adhesive has an important influence on the fluidity, wettability and uniformity of the adhesive. In the dry composite, the viscosity value of the adhesive should be controlled within the appropriate range, if the viscosity of the adhesive is too high, the dispersion and leveling may be poor, affecting the wettability of the surface of the composite substrate, and failures such as coating leakage and bubbles may occur during the coating process. When the two-component two-liquid reaction adhesive is used, it is necessary to dilute the adhesive by adding diluent in order to ensure uniform coating and conducive to infiltration. Diluents include toluene, ethyl acetate, methyl ethyl ketone, etc. Toluene is being phased out because it is not conducive to environmental protection and is easy to cause bubbles. Methyl ethyl ketone is used less because of its high price and not very good affinity with adhesives. At present, the most used diluent is ethyl acetate. Diluent can not contain water, alcohol, amine, etc. If the water content is more than 0.2%, because the volatilization rate of water is much lower than that of ethyl acetate, the volatilization rate of solvent will be greatly reduced, and the spreading and hardening of adhesive will be affected. After the composite of BOPP film and CPP film, the composite product will pro...