How to choose raw materials for retort-resistant composite packaging ink?

    In the early 1980s, China began to introduce composite packaging production lines from Japan, Italy and other countries and put them into production. As of a few days ago, there have been hundreds of composite packaging production lines in China. The printing inks used for composite packaging are divided into two categories, one of which is light packaging composite packaging inks, which are mainly used for printing BOPP film, and then extrude the composite PE film to make instant noodles, small foods, and cosmetic packaging bags. The other is cooking-resistant composite packaging ink, which is mainly used to print PET, NY film and then dry composite aluminum foil, CPP film to make high-temperature steamed meat, poultry, seafood and other soft can packaging.

Here mainly introduces the raw material selection of retort-resistant composite packaging ink:

1. Resin
    Polyurethane resin is usually used as the bonding material resin of the retort-resistant composite packaging ink, because it has extremely high adhesion to a variety of materials. For polyurethane resin
Coatings and ink binders show excellent process performance and physical and mechanical properties. Inks made of polyurethane resin binders not only have good viscoelasticity, but also have excellent high and low temperature performance and rubbing resistance.
    Polyurethane (polyurethane for short) resin is a type of macromolecular compound that contains more carbonate groups (-NH-COO-) on the main chain of the macromolecule. The resin used for the ink binder should have good fluidity, so the resin must be a macromolecule with a linear structure. Generally, there are two methods for synthesizing linear resin. One is directly granulated after bulk polymerization. This method has a short synthesis cycle and can be continuously produced. However, the system has a large viscosity in the middle and late stages of the reaction, and the reaction heat is difficult to release, and the reaction temperature is difficult to control.

    This leads to partial overheating of the reaction system, widens the relative molecular mass distribution of the product, and easily produces cultural cross-linking, which makes the resin solubility worse and the fluidity lower. The other method is solution polymerization. This method has a stable polymerization reaction, easy to control, and a wide range of reaction conditions: the product has good linearity, relatively narrow mass distribution, and the obtained resin has good fluidity: but its disadvantage is the monomer in the system Low concentration; low reaction speed and long reaction period.

2. Pigments
    The following pigments were selected according to factors such as the heat resistance of the pigment, compatibility with the resin, and price.
Yellow: benzidine yellow G combined with benzidine yellow 10G
Red: Lithol Crimson 243
Blue: Phthalocyanine blue
Black: Pigment carbon black
White: Titanium dioxide Rutile grade DTR-01
Lightening agent: OT Calcium

3. Auxiliary resin and additives
    The ink made from a single polyurethane resin has good dryness, adhesion fastness, peel strength, and cooking resistance, but the ink is poor; and the contradiction between thermal adhesion and resolubility of the ink is difficult to solve. When the relative molecular weight of the resin is large, the viscosity of the resin solution is higher, and the thermal adhesion is better, but the resolubility is poor. When ink printing is easy to paste and the relative molecular weight of the resin is small, the viscosity of the resin is lower, the resolubility is improved, but the thermal adhesion is reduced.
In order to solve these problems, the method of mixing auxiliary resins and adding auxiliary agents can be used to improve the ink properties, thermal adhesion and resolubility of the ink. Can use vinyl chloride-vinyl acetate copolymer resin, butyral resin, cellulose resin, rosin ester, etc. The auxiliary agent selects BYK's VP-101 ink auxiliary agent.

4. Solvent
    Comprehensive consideration of the solvent's influence on ink properties, ink properties, resin solubility, solvent price, toxicity and other factors: you can choose mixed solvent H-42, its composition is; ester: ketone: DOX: DMF=45:30:20: 5.
This kind of ink is suitable for printing on rotogravure printing machines, and the printing speed is 60-150m/min. It is mainly used for printing PET film and NY film. The ink has excellent adhesion fastness and can be used for dry composite aluminum foil and CPP film. After the bag is made, the food is put into the food under low temperature (60℃-85℃), medium temperature (85℃-100℃), high temperature (101℃-121℃) for 30 minutes, and the printed product will not change color, no foam, and composite layer. not separated. The oil resistance and heat resistance of the ink meet the requirements of food packaging.