Residue of cigarette odor - Influence of ink

With the increasing awareness of environmental protection and the concern for food safety, people have made increasingly clear and strict requirements on the safety and environmental protection of various packaging materials, especially in the field of food packaging. Cigarettes as a special consumer goods, consumers are very sensitive to odors in the process of smoking, cigarette odor odor will make cigarettes odor and affect the health of smokers, cigarette manufacturers therefore put forward various requirements for cigarette packaging materials, The residual solvent of cigarette packs is one of them.

The so-called residual odor of the cigarette pack ink is that the pack, after drying, contains an irritating, even harmful, abnormal smell. At present, the residual odor of cigarette packets is generally determined by chromatographic analysis and human olfactory organs. .

The reasons for the residual odor of the cigarette pack ink are mainly the following three conditions: the residual solvent odor of the ink; the resin odor in the ink; the odor of the auxiliary agent in the ink. The following specific analysis of these three reasons.

1. Solvent odor of residual ink At present, domestic cigarette package printing is mainly based on gravure, lithographic, screen and flexo printing. Gravure printing accounted for a considerable proportion. The inks used are solvent-based inks, water-based inks, offset inks, and UV inks.

In gravure inks, toluene, butyl acetate, isopropyl alcohol and other solvents with strong odors and toxicity have been used in the past. In some developed countries, aromatic solvents like toluene have been banned from foods. Packaging ink. To strengthen competitiveness, tobacco companies also hope to strengthen control in this regard. After scientific demonstration, major tobacco companies also made corresponding requirements for the types and contents of solvent residues on the smoke labels, and clearly specified that no aromatic solvents (benzene, toluene, ethylbenzene), and ketone-free solvents should be included in the printing ink for cigarette packages. , No isopropyl alcohol, n-butanol, butyl acetate and other toxic, harmful, heavier, slower volatile substances, and further to the residual content of ethyl acetate, n-propyl acetate solvent residue in cigarette packs also made clear Provisions. Most cigarette pack ink manufacturers have done this with gravure inks for cigarette packs. However, the alcohol ester-dissolving ink system is mainly based on ethyl acetate, n-propyl acetate, etc. Therefore, the residual solvent of esters in cigarette packets is still high. Although water-based gravure printing inks have attracted attention as a solvent-based ink replacement system, the printing performance and quality of water-based gravure printing inks still fall short of the standard for solvent-based gravure inks. This is mainly due to the higher surface tension of the water, which makes it difficult for the ink to wet the plate and the substrate, and the drying is slower. The printing effect is not ideal. At the same time, in order for water-soluble inks to be used on gravure printing machines, not only inks and resins require advanced technology, but also existing gravure printing equipment needs to be improved, plates need to be redesigned, and more effective drying ventilation equipment is needed. Because of the use of components made of corrosion-resistant materials, water-based gravure inks have not yet been popularized in cigarette gravure printing. Therefore, the development of all-alcohol-based gravure inks will also be put on the agenda. It is believed that all-alcohol-based gravure inks for gravure printing will solve the health problems of solvent inks and the influence of residual solvents on the smell of cigarettes. Contribute to the problem.

On the other hand, the odor of the solvent remaining in the ink can be controlled by the following aspects.
(1) Do not use aromatics (benzene, toluene, ethylbenzene), ketones, isopropanol, n-butanol, butyl acetate, etc. Solvents that are toxic, harmful, heavier, slower, and more likely to remain. Ethanol, ethyl acetate and n-propyl acetate are used as the main solvents. In addition, solvents with higher purity and more stable quality should be used and the contamination of solvent-packing drums and ink packaging drums should be avoided.
(2) Under the premise of guaranteeing ink printability and performance, using alcohol, ethyl acetate, and n-propyl acetate solvent to release faster and easier ink will help reduce the residual odor of cigarette packets.
(3) Under the premise of ensuring the good development of the printing process and the quality of printed products, try to fully dry the cigarette packs so that ethanol, ethyl acetate, and n-propyl acetate solvents are released as much as possible, which is good for reducing the residual odor of cigarette packs. In general, the higher the temperature of the printing environment, the lower the humidity, the slower the printing speed, the higher the hot air temperature of the oven, and the smaller the printing area, the easier the ink on the prints will dries, and the more residual solvent content on the cigarette packs is. Small, the lower the smell.

In cigarette UV inks, generally do not contain solvents, the polymeric prepolymer used generally have a large viscosity, UV inks and UV varnish need to have a viscosity to adapt to the coating machine when coating, usually by adding 20% ​​~ 80% of the active diluent monomer reduces the viscosity of the polymerizable prepolymer, while the active diluent monomer itself polymerizes to become part of the cured film, while the active diluent monomer added is a low molecular weight material. They generally have certain volatility and irritation and are still harmful to the environment and the human body. Due to the incomplete curing of UV inks and UV light oils, there is a certain activity to dilute the irritating monomer.

In the selection of UV inks, UV curing inks can be cured by using fast curing, low skin irritation, and low toxicity. In addition, you can also choose a new type of water-based UV ink, water-based UV inks do not have to use active dilution monomer to adjust the viscosity, but water or thickener to control the rheological properties of the ink to solve the volatile and irritating problems, Is a variety of ideal environmentally friendly products,
In a water-based flexo printing ink, the solvent of the aqueous flexo printing ink is mainly pure water. In addition, a small amount of ethanol, co-solvent and various additives are also added. Therefore, the solvent residue is low.

2. Resin odor in ink The resin used in the ink is mostly solid, and the odor of the resin is mostly determined by the process of resin raw material and resin synthesis. For example: The ink made of rosin modified resin has certain rosin smell after drying and curing. The ink made of solution acrylic resin has a certain acrylic monomer odor after drying and curing.

3. The odor of the auxiliary agent in the ink is small in the proportion of the auxiliary agent in the ink, but it has a great effect and can improve various properties of the ink, such as ink suitability, printability, ink film properties, and drying. Sex, and post-processing suitability.
The odor of the auxiliary agent is mainly due to the odor of the auxiliary agent itself and the odor of the auxiliary carrier solvent, for example: Some photoinitiators (such as BP) in the UV ink and UV varnish have an odor due to the incomplete curing of the ink. After a certain photoinitiator odor, due to the need for stable PH value in water-based inks, high-boiling organic amines are often added to the ink, so that the ink has a certain degree of amine after drying.

Source: China Tobacco Packaging Ink Information Network