Analysis on the application points of Zhihuo super

2022-07-31
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Analysis on the application points of super Lifu 314 ink

1. adaptability of ink and substrate film

super Lifu 314 ink (hereinafter referred to as 314 ink) is a two liquid reaction type cooking resistant surface printing ink. The applicable film substrates are mainly PE and NY films, and the film surface wetting tension is required to reach (4.0 ~ 4.2) × N/M (ordinary surface printing ink requires the wetting tension of the film to be 3.8 × N/M). A certain amount of plasticizer is added to the film forming process or resin masterbatch. The 12 agents can be known through the appearance of the equipment. These plasticizers gradually precipitate on the film surface, which will seriously affect the adhesion fastness of the ink, and after processing, such as boiling. Ink fading, dyeing and other quality problems occur during cooking, resulting in huge quality loss. Therefore, when using 314 ink, the selected film should be tried out before being put into mass production

2. solvent ratio and ink viscosity

314 ink belongs to polyurethane ink. The main solvent used is butanone. Generally, it is required that the content of butanone in the mixed solvent should not be less than 30% and the purity of butanone should be more than 98.5%. Otherwise, it is easy to cause poor solubility of the ink with the evaporation of butanone during the long printing process, so that the viscosity increases and the fluidity is poor, resulting in blocking, pasting Discoloration, etc. In addition, the moisture content in the mixed solvent should also be strictly controlled. When using 314 ink in summer, it is best to prepare a mixed solvent with slower volatilization speed. For example, under the conditions of room temperature 30 ~ 35 ℃, relative humidity 60% ~ 70%, the basic ratio of the mixed solvent can be set as butanone 40%, toluene 30% and butyl 20%. On this basis, appropriate adjustments can be made in combination with the depth of the printing plate hole and the speed of printing. When used in winter, the volatilization speed of the mixed solvent can be faster. For example, when the room temperature is 0 ~ 10 ℃, the basic ratio of the mixed solvent can be set as 50% of butanone, 30% of toluene and 20% of ethyl ester

if conditions permit, the lower the viscosity of 314 ink, the better. If the viscosity is low, the ink has good fluidity. The ink transferred to the film is thin, the solvent is volatile, and it is not easy to block the plate. At the same time, using more diluents is also conducive to reducing the manufacturing cost of the packaging film. However, for some individual colors, the hole of the plate roller may be deep, or the pattern area may be large. If the ink viscosity is too low, it will often cause problems such as printing blooming and unevenness. At this time, it is necessary to adjust the viscosity separately

314 ink has high color concentration and solid content. When used in low-speed gravure printing press, the ink dilution is about 50% ~ 80%; When used in high-speed gravure printing press, the dilution can reach 80% ~ 100%. As the drying speed of the ink is relatively fast, it is necessary to supplement the dilution solvent in time during the use process to ensure that the viscosity of the ink in the ink tank is always consistent. This is also the key point of the use of 314 ink, which must be paid attention to

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3. the ink needs to be used with hardener

the purpose of adding hardener is to increase the adhesion fastness of the ink to the substrate and improve the resistance of the ink layer. The use amount of hardener is generally 8% ~ 10%. When adding hardener, pay attention to mixing it with mixed solvent before adding it to the ink. Some users directly add hardener to the ink tank, which is a serious operation error. Due to the high viscosity and small amount of hardener, it is difficult to evenly disperse in the ink, which is easy to cause the hardener to precipitate at the bottom of the ink tank, resulting in quality problems such as product fading. In summer, due to the high room temperature in the workshop and the vaporization heat generated during the evaporation of the solvent, the moisture in the air is mixed into the ink, and the hardener in the ink first reacts with the moisture, which will also cause the imbalance of the hardening dose in the ink and cause color fading. In order to have enough hardener in the ink, a certain amount of hardener can be added 2 ~ 4 hours after printing according to the specific situation, and it should not be too much, otherwise the heat sealing performance will be affected, especially in the heat sealing part, which should be paid attention to. In view of this situation, during the layout design, it is also necessary to avoid designing and printing graphics and text at the heat sealing place, because 314 ink and hardener do not have heat sealing performance

4. Oven temperature

when using two liquid reactive surface printing ink, the oven temperature of the printing machine should be slightly higher than that of other inks, which is more conducive to the reaction between the ink and the hardener and increases the adhesion fastness to the substrate. However, as the substrate for printing is coextruded PE film, the temperature it can withstand is limited, so the oven temperature generally does not exceed 70 ℃. If the substrate is thick and the printing speed is fast, the oven temperature can be adjusted to about 65 ℃. At this time, pay close attention to the overprint accuracy, because too high a temperature will stretch the film material and cause inaccurate overprint. Some users will increase the tension and reduce the oven temperature due to poor film flatness or the existence of ruffles. These practices are very inappropriate, because it is easy to cause product quality accidents of two liquid reaction type cooking resistant surface printing ink. Note: do not use 314 ink when the oven temperature is lower than 40 ℃

5.1) treatment of residual ink in runner design

after use, the remaining 314 ink must be strictly sealed and stored. When it is reused, it must be filtered first and mixed into the new ink at a quantity of less than 30%. If the remaining ink has been seriously degraded or whitened, it must not be used

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