Preparation of "green" printing ink
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With the rapid development of the global economy and the continuous improvement of the quality of life of the people, people's awareness of environmental protection and health is constantly increasing. Water-based inks have become more and more concerned because of their environmental advantages and become the direction of the development of the ink industry. And trends. The water-based ink is abbreviated as ink, which is mainly processed by water as a solvent. Compared with other printing inks, water-based inks do not contain volatile toxic organic solvents, so the health of the printing press operators during the printing process. No adverse effects, no pollution to the atmospheric environment, no pollution to the printed matter itself, known as "green" printing ink. Because the ink has the characteristics of non-flammable, it can also eliminate the hidden dangers of inflammable and explosive in the printing workshop, which is conducive to safe production. Of course, the application range of ink and ink is different now. The ink is mainly offset printing, and the ink is mainly flexographic and gravure. In developed countries such as Europe, America and Japan, ink has gradually replaced ink, becoming a special ink for printing methods other than offset printing. In the United States, for example, 95% of flexographic prints use ink and 80% of gravure prints use ink. Ink is also especially suitable for packaging and printing products with strict sanitary conditions such as tobacco, wine, food, beverages, medicines and children's toys.
In recent years, with the continuous modification of resins, the structure of new coatings and inks has undergone great changes. In order to meet the requirements of environmental protection, developed countries have developed many water-based inks, which have begun to be used in paper and plastics. Film, packaging and special printing. The annual production of water-based inks in China is about 100,000 tons, mainly for the production of low-grade paper packaging printing inks. At present, the film-forming materials for aqueous inks are mainly acrylic resins, which are due to the advantages of high stability, good gloss, rheological properties and surface adsorption properties. This experiment uses solution polymerization method, using methyl methacrylate, a-methacrylic acid, acrylic acid, butyl acrylate, vinyl acetate, ammonia water, triethylamine as the main reagent, and adding ammonium persulfate (initiator); Sodium bisulfite (reducing agent); sodium lauryl sulfate (emulsifier) to prepare an acrylic resin. The above-mentioned resin is added into a pigment, an antifoaming agent, a dispersing agent and the like to prepare an aqueous ink, and the film forming property, drying time, water resistance and abrasion resistance are measured, and the standard required for printing of the water-based ink is achieved.
1. Preparation scheme of aqueous resin
2. Preparation method of aqueous resin
Add a uniform amount of the basic monomer (methyl methacrylate, a-methacrylic acid, acrylic acid, butyl acrylate, vinyl acetate reagent) to a 2000 mL three-necked flask in 1/3 amount, then add water and isopropyl Alcohol, heating, stirring to reflux (about 80 ° C or so), adding reducing agent, initiator, while starting to add 2 / 3 amount of monomer and vinyl acetate remaining (the first one added acrylamide, the program added more than two Polyvinyl alcohol), the titration time is about 1 h. When all the monomers are completed, the temperature is kept at about 85 ° C for 2 h and the polymerization inhibitor is added. After 2 h, the temperature is lowered to 60 ° C, and ammonia water is added for neutralization. At the same time, it was diluted with water, and the pH was adjusted to about 8 to 9. After stirring for 0.5 hour, it was cooled to room temperature and then poured out.
3. Development of water-based ink
Add the resin of formula 1, 2, 3 to 240 mL of water/alcohol mixture (4 parts water and 1 part alcohol), stir evenly, add to SFJ container with shearing, stirring and emulsifying function, then add Disperse pigment (W-45 pigment carbon or Cabo-400R carbon black, ie CB-400) 100g, defoamer 10mL, dispersant 10mL and other additives, after high-speed shearing, emulsification, dispersion, sanding, and then Add 500mL water/alcohol mixture, continue stirring for 30min, pour the product into the filter vessel, and filter it to obtain the finished ink. Continue to add water or alcohol to adjust to the desired viscosity.
4. Performance of waterborne resin
(Viscosity is based on GB1723-9)
5. Performance of the ink
The performance test is a printing test on a plastic film. The solubility of the film means that it is immersed in water for 60 hours and immersed in 4% acetic acid for 45 hours, and the color of the film does not fall off.
6 Conclusion
6.1 Tests show that the addition of polyvinyl alcohol and vinyl acetate modified acrylic resin is suitable for the printing of PE film, and its performance in all aspects is superior;
6.2 adding enoic acid in batch during the polymerization process can improve the hydrophilicity of the product (called semi-continuous hunger supplementation), which can make the polymerization reaction more complete;
6.3 The polymerization temperature should not exceed 90 °C, the polymerization time should be 4 hours, the neutralization solution should be stable with ammonia water and triethylamine, and the pH value is better at 8-9;
6.4 Compared with similar products, the experimental products have better solid content and viscosity. Experimental tests have shown that the performance specifications of water-based inks formulated with acrylic resin meet or exceed national standards and practical application requirements.