Technical Highlights of Gravure Printing Inks for Flexible Packaging

Plastic gravure ink is a kind of mixed dispersion liquid, and the key to production lies in the fact that the ingredients can be fully mixed and dispersed. The basic process of plastic ink includes:

1. The production of binders dissolves a variety of compatible resins through a solvent, and becomes a uniform viscosity liquid, and the equipment is mainly a reaction kettle and the like. At present, some well-known ink manufacturers in the country can directly produce resins with different functions and combine them into their own unique connection materials, such as Tianjin Toyo, Hangzhou Hanghua, Zhejiang New Oriental and other ink manufacturers.

2. Dispersion, milling The pigment, the binder, the solvent and the additives are mixed and ground into a semi-finished product.

3. Adjustment, finished product packaging through a variety of control methods; test a variety of indicators, stable after getting the finished product.

The ink production equipment has a great influence on the stability of the ink product quality. In particular, the quality of the grinding is directly related to the stability of the ink and the printability. Therefore, a good ink product must be based on an excellent formula, with advanced production technology and equipment.

Use of plastic ink

In addition to the classification methods mentioned above, plastic gravure inks can be divided into table printing inks and compound inks according to the way of printing and processing. At present, there are many domestic ink manufacturers can produce these two types of inks, from which aspects we choose the ink we need? We must choose the printing substrate film, printing conditions, product quality requirements, post-processing conditions, end-use to choose Ink, at the same time, must understand the overall performance of the selected plastic printing ink, including the type of ink, the dilution solvent, and the conditions of use.

1. The functions and characteristics of different types of inks are shown in Table IV.

2. The viscosity of the ink.

The viscosity of the ink has a direct effect on the quality of the printed product. The viscosity of the ink in production is determined by the specific process parameters, and the viscosity is also related to the temperature, humidity of the shop, the speed of the printer, and the dilution solvent (purity, solvent formulation) used for the concentration of the ink. In order to make printing and carry it out, we must control the viscosity of the ink. If the viscosity of the ink is too high or too low, the prints, text, patterns, and dots will be incomplete. Viscosity is too low, the surface ink will make the product not bright, hair, abrasion resistance, abrasion strength weakened, adhesion is not enough and fade phenomenon. The appearance of composite ink will result in incomplete layered dots, poor hiding power, and spotted film leakage at the end of printing, especially when compounded with aluminum foil and aluminized film.

In the polyurethane ink composition, butanone is the main solvent of the ink and belongs to the fast volatile ink. If the volatilization rate of the ink and the solubility of the added solvent cannot be controlled, it may cause precipitation of the polyurethane resin, flocculation of the pigment, precipitation of the ink, and the occurrence of a series of troubles such as non-coloring, dirty printing, discoloration, and discoloration. In order to make the solvent volatilization and dissolution of the polyurethane ink in the printing process parallel, we must adjust the dilution solvent reasonably so that the ink is always in a good fluid state during printing.

Development of ink for flexible packaging

In China's plastic flexible packaging market, small and medium-sized enterprises account for the vast majority of the production of technical products is not high, or the products are similar, so the competition is very fierce, and finally often focus on the reduction of costs, while ignoring the product's technical requirements and health Claim. The use of plastic ink in China has increased significantly, but it has not been correspondingly improved in terms of safety and health performance, there is a significant lag. Toluene and other aromatic solvents are still used in large quantities, and chlorinated and acrylic inks account for more than 60% of the ink market. Since China’s accession to the WTO, China’s economy and trade with other countries have become closer, and “internationalization” has greatly driven the development of the Chinese plastic ink industry toward environmental protection. There are quite a few plastic flexible packaging companies and ink manufacturers that are passively accepting status rather than consciously taking the initiative. In domestic plastic packaging, ink must be associated with safety and hygiene. As far as its solvent system is concerned, it is currently developing toward the absence of benzene and alcohol. In terms of alcohol-soluble ink technology, Shanghai Si Kebai, Zhejiang New Oriental, and Shanghai DIC are among the leading companies. As far as its connection material technology is concerned, it is heading towards the development of polyester urethanes. Because of its low toxicity, polyester polyurethane inks are suitable for printing on PET and NY materials, and have excellent performances such as high-temperature cooking resistance, freezing resistance, and abrasion resistance. They will gradually replace the chlorinated polypropylene inks. New Oriental Ink's polyester inks currently account for more than 50% of the company's total ink production and become the company's core competitiveness products. In terms of its pigment system, plastic packaging inks will develop toward the direction of free heavy metal pigments. If the domestic pigment manufacturers cannot integrate with international manufacturers at this point, they will face the risk of being eliminated.

Since the gravure printing technology entered the country, it has been in a steady development trend and its development prospects are promising. This is different from other countries such as Europe and the United States. In China's food plastic flexible packaging, gravure printing has absolute advantages. In large-scale supermarkets, Yingying’s eye-catching food and daily product packaging are gravure products. However, in Western Europe, flexo printing accounted for more than 70% of food plastic packaging, and gravure food packaging bags continue to decrease. According to the current gravure development situation in China, we have reason to believe that gravure will continue to maintain its absolute leading position in the printing of plastic flexible packaging. Of course, plastic flexible packaging inks must move toward safety and hygiene. With China's accession to the WTO, packaging requirements will gradually be brought into line with international standards, and the country will gradually formulate more stringent standards. Manufacturers who supply raw materials for flexible packaging companies must plan ahead and adjust their technological orientation to meet the needs of the development of the times in order to be invincible in the market.

--- Flexible Packaging News