Solvent-type gravure compound retort pouch ink formulation and printing performance (below)

4, the selection of high temperature resistant cooking bag ink wax powder

The compound high-temperature retort pouch ink formula used for gravure printing usually contains some special high-temperature resistant wax powder, which can provide excellent anti-grinding and scratch resistance for the high-temperature resistant ink film of the print, preventing adhesion and increasing the ink on the machine. Liquidity, improve printability and improve post-processing performance. Since these special wax particles have a diameter of about 5 microns, which is larger than the diameter of the pigment particles and the thickness of the ink film, these wax powder particles can highlight the ink film after the ink is printed and dried to make the ink film surface rough. When the plastic film is printed on the ink for a long time after being wound up, the rough ink film is advantageous in preventing the printing surface from sticking to the back side of the plastic film; it also facilitates the uniform coating of the glue on the post-processing composite and enhances the compounding of the film. degree. Adding these special wax powders to the ink can also eliminate the disadvantages that the ink ink film can easily fall off the roller during high-speed printing due to excessive pressure.

Most of the formula design of composite high-temperature retort pouch ink for gravure printing is to use molecular straight-chain synthetic polyethylene wax with high melting point and strong hardness. There are two methods before and after the ink production process. 0.5-1.0% of the total weight of the ink. Under normal circumstances, it is added before the coarse grinding of the ink, which is beneficial to dispersion and improving the fluidity; however, attention should be paid to the fact that the grinding temperature should not be too high, so that these wax powder particles are not deformed and agglomerated, and the performance of the wax particles is affected. It is also formulated with ink system resin and organic solvent made of paste ---- wax paste, which is added during the tackifying and color matching stage of the ink; but to do so, it is necessary to prevent certain organic solvents with strong penetrating power from dissolving the wax powder particles. Produce recrystallization and return to coarse, lose the performance of the special wax powder.

5, high speed printing antistatic agent selection

When the gravure plastic ink is printed at a high speed, due to accumulation of static electricity, it may cause problems such as offset, blur, spots, beards, and edge repulsion. In serious cases, fire or explosion may occur. Therefore, the purpose of adding an antistatic agent to the ink is to reduce the surface resistance of the plastic film during the printing process and eliminate the static electricity to solve the above-mentioned problems in the printing. Anionic antistatic agents are generally used in plastics and inks, including higher fatty acid salts, alkyl phosphate salts, alkyl sulfate salts, and sulfonate salts, which are soluble in water, ketones, and alcohols. Organic solvents such as benzenes and benzenes are sold as aqueous solutions of organic solvents containing 30 to 60% of actives. The composite high-temperature retort pouch ink used for gravure printing is mainly selected as the antistatic agent of ethyl phosphonate isopropanol solution, and the added amount accounts for 0.1--0.4% of the total amount of ink without any adverse effect on the ink property.

6, adhesion promotion resin and fumed silica powder selection

In the polyurethane and vinyl acetate resin ink systems of the composite high-temperature retort pouch ink for gravure printing, since the flexibility of the vinyl acetate resin itself is not enough, it is necessary to use the adhesion promoting resin to improve the flexibility; the composite for gravure printing High temperature resistant cooking bag ink formula will add some modified chlorinated polypropylene resin solution, its solid content is generally about 15-25%, improve the adhesion of polyurethane ink on plastic film, enhance the dispersion effect and fluidity.

Fumed silica powder, also called matt powder, is generally easy to disperse after it is organically surface-treated. Its role in gravure printing for composite high-temperature retort pouch inks: A. Prevents pigment settling and maintains long-term rheological properties and fineness of the ink. B. Improves ink sag performance when the ink is printed on the machine. The generation of watermarks; C, also can be like wax powder, is conducive to the uniform coating of adhesives, improve the composite fastness.

7, the choice of organic solvents in gravure high temperature cooking bag ink system

The plastic gravure ink is mainly formed by the solvent evaporation and drying. When the ink is printed on the surface of the substrate, the ink film thickness decreases and shrinks due to the volatilization of the solvent. The solvent evaporation of the ink solvent film is mainly divided into two stages: the first is the "wet stage" controlled by the surface layer; the second is the "dry stage", and the solvent volatilization rate is controlled by the diffusion of the solvent inside the integral ink film. When there is a true solvent, it ensures that the resin and other polymers fully stretch and interact with each other, and the leveling property is good. If the true solvent volatilizes too quickly and only the co-solvent remains in the residual solvent, the polymer molecules tend to form a tight curl or even precipitate out. It is particularly important that solvent evaporation causes endothermic cooling and a rise in polymer concentration, which increases the surface tension of the ink film and causes the solution to flow from a low surface tension zone to a high surface tension zone. This is a peak-wool flow, which easily produces “orange peel”. And floating color phenomenon, so to maintain the necessary amount of true solvent is an important condition to ensure the ink film leveling.

For polyurethane and vinyl acetate ink systems, toluene, xylene, ethyl acetate, butanone, isopropyl alcohol are common solvents, but also acetone, methyl isobutyl ketone, ethylene glycol monobutyl ether, Propylene glycol methyl ether and other special organic solvents. Among them, benzenes and alcohols are only auxiliary solvents for polyurethane and chloroacetic resins. Ketones and esters are true solvents, but the evaporation rate is too fast. Therefore, special solvents such as methyl isobutyl ketone, ethylene glycol monobutyl ether, and propylene glycol methyl ether are also used to adjust the volatilization rate and solubility, enhance the dispersive power of the mixed solvent, and increase the dissolution parameters so that the ink always presents a good fluid. State, to ensure the smooth progress of the printing work.

Solvent-type gravure composite high-temperature cooking bag ink application performance brief introduction

Compound high-temperature retort pouch inks for solvent-based gravure printing use a high-chlorine, medium-viscosity trivalent chloroacetic resin, a special high-temperature-resistant polyurethane resin as the main binder, and a series of special additives and organic solvents. The organic pigments with high temperature resistance are evenly stirred, dispersedly ground, and tackified and colored. It is suitable for low-speed to high-speed high-temperature plastic film inside (composite) printing, the substrate is generally RCPP, PET, BOPP, NYLON (nylon) and AL (aluminum film) and other high-temperature composite plastic film. The thin film products printed with this type of ink can be used in ordinary composite processes, and are more suitable for high-temperature cooking compound processes. The ink film solvent residues are low in residue, odorless and non-toxic, environmentally safe, and can be used for the packaging of foods and medicines. , in line with health requirements.

The gravure compound high-temperature cooking bag ink has the following characteristics:

1. Low viscosity, good leveling property, large solid content, bright color, high color concentration, good dot reproducibility, suitable for multi-layer color printing.

2, high attachment fastness, suitable for a variety of printing films.

3, excellent printability, good ink transfer, suitable for different machine speed and depth.

4. The printed product can withstand high-temperature cooking, and can be boiled (80-100°C) and high-temperature cooking (100-130°C) when used in one-component, and can be printed by adding the curing agent (2-5%) in two-component printing. The product's high temperature resistance, film forming properties, printability, and composite fastness.

5, the composite performance is good, the ink film has a high peel strength, up to 5N/15mm - 10N/15mm; and after 120 °C high temperature cooking, the peel strength does not fall but rose.

Conclusion

Some scholars have said that market information has given birth to industrial opportunities, market demand has stimulated technological innovation, and technological innovation has changed the market landscape; our factory also has such a slogan: "Market needs are directives, and quality is first-rate." In order to develop and surpass the world level, the composite high-temperature cooking bag ink used for gravure printing in our ink market requires our ink workers to have cutting-edge technical design, brave technological innovation and reasonable production management. We must not evade the challenges of the three, and we should face them, study them, and perfect them. This is what we hope to discuss with your peers about the purpose of selecting and printing the compound high-temperature cooking bag ink for commercial gravure printing.

Source: 21st Century Fine Chemicals Network