The ink for food packaging appears "migration" phenomenon. How can consumers tell the packaging safety?

Ink directly determines the tone, color and clarity of the image on the printed matter, so ink plays an important role in printing.

At present, more than 95% of plastic flexible packaging is printed by gravure printing. Our common Printing Ink is generally made of chlorinated polymers. In the process of production and use, aromatic solvents such as toluene are needed to dissolve and adjust the viscosity of the ink. Therefore, in the process of production and printing, a large number of harmful gases will be volatilized, which will destroy the ozone layer of the atmosphere and endanger the health and safety of workers (fire). The safety of food soft packaging products is also very poor, benzene is easy to remain in the dry ink microfilm layer, and xylene is more likely to cause the increase of benzene residue. Benzene residue will pollute the food in the package. At present, although alcohol-soluble ink is environmentally friendly, it will still pollute the environment, and there will be solvent residues. The PE (polyethylene) film made of flexible packaging has poor leakage resistance and strong adsorption, which easily pollutes the PE film in the packaging with the unpleasant smell of ethyl acetate.
According to the regulations of various countries on the use of ink, at the end of last century, countries and regions such as Japan, South Korea and Southeast Asia have eliminated toluene printing ink. In the 1980s, the United States advocated Water Based Printing Ink, and banned the use of solvent based printing ink.
In recent years, food safety problems caused by food packaging have occurred continuously. Ink is an important part of food packaging and printing, and its own harmful substances will migrate to food with the change of environmental time, causing pollution to food.

01 Causes of Migration of Ink for Food Packaging

1. Contact migration
That is, the ink migrates from the printing surface to the non-printing surface of another layer, so that it contacts with the product and migrates.
2. Diffusion and migration
That is, the printing ink of food packaging permeates from the printing surface to the non-printing surface so as to contact with the product and migrate.
3. Evaporative migration
That is, some substances in ink volatilize and migrate. When volatile chemicals and compounds in ink are transferred to internal products by evaporation or from heated, baked or boiled food.
No matter what kind of migration, its ultimate target is the raw material composition of ink itself. Only by selecting raw materials that meet the requirements of laws and regulations and controlling the safety of ingredients from the source is the ultimate weapon to reduce this risk.

02 legal provisions on food packaging safety
Article 3 of the European Framework Regulation (EC)1935/2004 on Food Contact Materials and Products stipulates that substances that migrate from food contact materials to food shall not:
-It is potentially harmful to health.
-Causing unacceptable changes in food composition.
-Change the flavor of food.
This law clearly defines the responsibilities of the packaging supply chain to ensure the safety of packaging. In order to ensure the safety of consumers, Switzerland issued the world's first ink regulation. The ink regulations drafted by Germany in 2016 were also released at the end of 2021, which stipulated the positive list of raw materials that can be used for food packaging ink, which is a further improvement of the European framework regulations on food contact materials. In the Asia-Pacific region outside Europe, China initiated the formulation of ink regulations for food contact materials in 2016. The consultation ended at the end of 2021, and the final version will be promulgated soon. India issued regulations on printing inks in 2019, which explicitly banned toluene inks and some o-benzene plasticizers. The promulgation of this series of laws and regulations means that the impact of ink on food safety has received great attention.

03 Can consumers tell which packages are safe?
It is generally difficult for consumers to tell which packages are safe and which are unsafe from the appearance, because the migration we usually talk about refers to the level of several parts per million (equivalent to the proportion of one candy dissolved in two tons of water), and it is difficult for us to identify such a low content through our senses. Maybe you will say, is such a low dose really harmful to your health? If you have some basic chemical knowledge, you will know that some substances will accumulate and exist in the body for a long time, so long-term accumulation and exposure will endanger your health to some extent.
Since it is difficult for consumers to distinguish between safe and unsafe packaging from the sensory level, they have to rely on the strong sense of social responsibility of enterprises in the packaging value chain to maintain the safety of packaging. Ink raw material suppliers provide transparent raw material information for ink manufacturers, including main components and possible impurities. Packaging suppliers provide reliable and reasonable packaging design, purchase qualified packaging raw materials, and discuss with brands how to ensure the safety of final packaging. This is a complex system engineering, which needs the full cooperation of the whole industrial chain to complete.

04 Future trend

Nowadays, Water Based Plastic Ink, as an alternative product of solvent ink, is recognized by more and more color printing and packaging industries because of its non-flammable and green environmental protection characteristics, and is also concerned by ink production enterprises and society in many aspects. It is an inevitable trend that the ink in flexible packaging printing is completely water-based.

To use water based Plastic Ink for printing, first of all, it does not need to use solvents, only water can be used. How much solvent can be added in the printing industry? For example, if you add 50%-100% solvent to ink, and mistakenly think that the more solvent you add, the better, and the lower the cost. Actually, 50%-100% of the solvent is added during the whole printing process. This is because the volatilization of solvent causes the viscosity of ink to change and is added. The faster the printing speed, the faster the volatility of the diluent to be prepared, and the more times the solvent is added. This is equivalent to increasing the printing cost. Therefore, it is not after 10 kilograms of ink is added to 5 kilograms of solvent that printing begins.

According to the standard of ink industry, high color density and low viscosity are good inks. Diluent is added to the ink only to reduce the viscosity of the ink. Make it suitable for printing, such as excessive addition, the color density of ink will decrease. The weight of the binder is reduced at the same time, so that a good product cannot be printed. Therefore, Water Based Ink only adds pure water, and it is added at one time (prepress). In the printing process, it won't cause color change because of viscosity change, and it won't be like ink, which is a waste product caused by adding thinner during printing, thus greatly improving the qualified rate of printed products. The cost of solvent is saved, and the appearance of waste products is reduced. This is one of the cost advantages of water based plastic ink.