Analysis of Improved Examples of Water-based Flexographic Ink Technology

Flexo printing is the "best and most promising" printing method. However, the environmental protection mentioned here is relative, although the solvent used in water-based inks is mainly water, but it does not rule out the intervention of some toxic substance chemicals, but the content is relatively small. As far as the international research progresses now, there is no water-based ink with little toxicity, which has a great influence on the constraints of printability. Our goal is to minimize the toxic content of water-based inks without affecting the printability. As the basic component of the water-based ink, the binder and the water are non-toxic, and it is natural to focus on the solvent used. When selecting solvents and designing water-based inks, adequate attention should be paid to the smell of solvents, toxicity to humans, air pollution restrictions, and safety. Solvents with unpleasant odours, solvents that are toxic to humans, solvents that are flammable and explosive, and solvents that are contaminated with air should be avoided.

1 Performance of solvents commonly used in the manufacture of water-based inks

Ethanol: commonly known as alcohol, is a colorless, transparent, liquid with a special aromatic odor. Industrial alcohol contains 95% ethanol. Due to its weak polarity, ethanol and ether solvents can improve the solubility of the resin and enhance the dispersion of the pigment, and can accelerate the penetration and inhibit the foaming phenomenon.

Isopropanol: Energy and water can be mixed in any ratio. Solubility, volatilization rate, and toxicity are similar to those of ethanol, but its odor is stronger. It is commonly used as a co-solvent in the manufacture of inks. Accelerate penetration and inhibit foaming.

Ammonia (liquid ammonia): There is a pungent odor. Liquid ammonia will attack some plastic products, rubber and coatings. In the event of heat or open flame, it is difficult to ignite and the danger is low; but if the mixture of ammonia and air reaches a certain concentration range, it will burn and explode in the event of an open flame. If oil or other flammable substances are present, the danger is higher.

Alcohol ether and ether ester solvents: There are many types of such solvents. Although glycol ethers and ether ester solvents are still widely used in China's ink products, since the 1980s, industrial hygiene experts have solemnly pointed out that the toxicity of glycol ethers and ether ester solvents is very serious. It has great harm to the blood circulation system, lymphatic system and animal reproductive system. In June 1982, the U.S. government limited the allowable concentration of ethylene glycol ether and ether to the minimum working environment to prevent the solvent from being absorbed by the human body through the respiratory tract, thus causing health hazards. The concentration of solvent vapor in the production site must be strictly guaranteed. Safety restrictions below. In Los Angeles, National Air Pollution Control No. 66 Regional Management Regulations stipulate that solvents with a mixture of hydrocarbons, alcohols, aldehydes, esters, ethers, or ketones with unsaturation should not exceed 5%; with 8 or more ethylbenzene The mixed solvent of aromatic molecules with more than 8 carbon atoms should not exceed 20%. In the United States, water-based inks complying with VOC regulations must meet the following two standards: I. In the ink composition of the use state, the proportion of organic volatile components (VOC) is less than 17%, and the water content is more than 75; II. Ink with less water content In use, non-volatile components are above 60% (water content).

2 Example analysis

1) Basic formula section

1 Abrasive base formula (take black ink as an example)
Pigment 120%
Acrylic resin solution 355%
Ethanol 150%
Ethylene glycol butyl ether 160%
Antifoaming agent 05%
Wax 10%
Water 200%

2 aminated resin liquid formulations:

J678 resin 370%
Ethanol 200%
ammonia
(Boiling point: -33) 230%
Deionized water 200%
(to be continued)

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