Analysis of Application Points of Chaolifu 314 Ink

1. Adaptability of ink and substrate film

Chao Lifu 314 ink (hereinafter referred to as 314 ink) is a two-liquid reaction type cooking resistant table printing ink. The applicable film substrates are mainly PE and NY film, and the film surface wetting tension is required to reach (4.0 ~ 4.2) × 10 -2N/m (ordinary surface printing ink requires the wetting tension of the film to be 3.8 x 10-2N/m or more). A certain amount of plasticizers are added to the film forming process or the resin masterbatch. These plasticizers are gradually deposited on the surface of the film and can seriously affect the fastness of the ink, and can be post-processed such as boiling. During cooking, ink fades, stains, and other quality problems occur, causing huge mass loss. Therefore, the use of 314 inks is first to trial the chosen film and put it into mass production.

2. Solvent ratio and ink viscosity

314 ink is polyurethane type ink, the main solvent used is butanone, general requirements butanone content in the mixed solvent should not be less than 30%, and the purity of butanone must be guaranteed to be above 98.5%, otherwise it is easy to print for a long time During the process, with the volatilization of butanone, the solubility of the ink is liable to be deteriorated, so that the viscosity rises, the fluidity is not good, and problems such as blocking, lamination, and discoloration occur. In addition, the content of water in the mixed solvent should also be strictly controlled. When using 314 ink in summer, it is better to prepare a mixed solvent with slower evaporation speed, such as under the conditions of room temperature of 30-35°C and relative humidity of 60%-70%. The basic mixing ratio of the mixed solvent can be set to 40% for methyl ethyl ketone, 30% for toluene, and 20% for butyl ester. On this basis, appropriate adjustments can be made in combination with the depth of printing plate and the speed of printing. When used in winter, the volatilization speed of the mixed solvent can be made faster. For example, when the room temperature is 0 to 1°C, the basic mixing ratio of the mixed solvent can be set to 50% of methyl ethyl ketone, 30% of toluene, and 20% of ethyl ester.

Under conditions permitting, the lower the viscosity of the 314 ink, the better. If the viscosity is low, the fluidity of the ink is good, the ink layer transferred to the thin film is thin, the solvent is volatile, and it is not easy to block the plate; at the same time, using more diluent also helps to reduce the manufacturing cost of the packaging film. However, for some individual colors, the roller aperture may be relatively deep, or the pattern area is large. If the viscosity of the ink is too low, problems such as hair prints, unevenness, etc. may occur, and the viscosity needs to be separately adjusted.

314 ink color density and solid content are relatively high, when used in low-speed gravure printing machine, the ink dilution of about 50% to 80%; when used in high-speed gravure printing machine, dilution can reach 80% to 100%. Since the ink drying speed is relatively fast, it is necessary to supplement the dilution solvent in time during use to ensure that the viscosity of the ink in the ink tank is always the same. This is also an important point for the use of the 314 ink and must be taken seriously.

3. Ink needs to be used with hardener

The purpose of adding the hardener is to increase the adhesion of the ink to the substrate and improve the resistance of the ink layer. The use of hardener is generally 8% to 10%. When adding the hardener, be careful to mix well with the mixed solvent and then add ink. Some users directly add hardener to the ink tank, which is a serious operational mistake. Because the viscosity of the hardener is high and the amount of the hardener is small, it is difficult to disperse evenly in the ink, which easily causes the hardener to settle at the bottom of the ink tank, resulting in quality problems such as discoloration of the product. In summer, because the room temperature is high, and the solvent generates vaporization heat during the evaporation process, the water in the air is mixed into the ink. The hardener in the ink first reacts with water, which also causes the imbalance of hardener dose in the ink. fade. In order to make the ink have enough hardener, a certain amount of hardener can be re-added after 2 to 4 hours according to the specific circumstances, and not too much, otherwise it will affect the heat sealing performance, especially in the heat-seal position, it should be Draw attention. In view of this situation, when designing the layout, the design and printing of graphic images should also be avoided at the heat-seal, because the 314 ink and hardener do not have the heat-sealing property.

Oven temperature

When using two-component reactive cooking resistant table-printing inks, the oven temperature of the printing press should be slightly higher than when using other inks, which is more conducive to the reaction between the ink and the hardener and increases the adhesion to the substrate. However, since the substrate is a co-extruded PE film, the temperature to which it can withstand is limited, so the oven temperature is generally not more than 70 °C. If the substrate is thicker and the printing speed is faster, the temperature of the oven can be adjusted to about 65°C. At this time, close attention should be paid to the accuracy of overprinting, because overheating will cause stretching of the film material and result in overprinting. Some users may feel uncomfortable due to poor film flatness or the presence of flounced edges, which may increase the tension and reduce the oven temperature. This is because it is easy to cause product quality accidents in the two-liquid reactive cooking inks. The 314 ink is used when the oven temperature is below 40°C.

5. The remaining ink treatment

After use, the remaining 314 inks must be strictly sealed and stored. When they are reused, they must be filtered first and mixed with new ink in an amount of 30% or less. If the remaining ink has been severely deformed or turbid, it must not be used.