Environmental pollution and governance issues in printing

Preventing pollution, managing the environment, and adhering to the strategy of sustainable development are the inherent requirements for China's integration into the world economy and the establishment of a modern enterprise system after China's accession to the WTO. In recent years, the environmental protection requirements for printing and packaging have become higher and higher at home and abroad. How should we deal with the actual printing industry? The principle of pollution prevention and environmental protection is the correct use of various chemicals. It is not only necessary to reduce waste at the source, but also to reduce the environmental impact of various chemicals in the production process.

In the printing industry, manuscripts, films, printing plates, inks, fountain solutions, coating solutions, and printer washings constitute an integral part of the printing process and are an important factor in printing. Some of them constitute a part of the printed product, and some of the liquid, solid waste that becomes solid after it is completed remains in the printing shop or enters the environment. We analyze this to facilitate effective control of environmental pollution by various factors. First of all, we must look for ways to use safe products to reduce or avoid environmental pollution. At the same time, we must find ways to rationally use the chemicals that we have to use to control the amount of chemicals used to reduce environmental pollution.

I. Main sources of pollution in the printing process

The first is ink. At present, the traditional solvent-based ink is widely used in the printing industry. The solvent-based ink consists of pigments, binders, solvents, fillers, and adjuvants. The solvents used are mainly aromatic hydrocarbons, esters, ketones, ethers, etc. Organic solvents, most of these solvents are toxic and can contaminate foods, medicines and cosmetics that are packaged; they are volatile, have a strong irritating odor, and can pollute the environment and affect the health of workers; organic solvents are flammable and easy to use. Explosion, there is a hidden danger of production safety.

The second is the fountain solution. The fountain solution is a necessary condition for ensuring the formation of a hydrophilic salt layer in the blank part of the printing plate. Currently, an alcohol dampening system is generally used on an offset printing press, and isopropyl alcohol is one of the additives of the fountain solution. Compared with the traditional water dampening system, this dampening method can greatly reduce the amount of water, but also avoid paper deformation due to excessive water and excessive emulsification of ink, thereby greatly improving the printing effect. However, the alcohol vapor produced after the evaporation of isopropanol is toxic, has bad odor, and has a harmful effect on human health. In many developed countries, the threshold value of isopropyl alcohol in the workplace is only 200 to 400 per cubic meter. In addition, isopropanol emissions also pollute the environment. Isopropanol is a photochemical oxidant that, like other trace gases in the vicinity of the ground, emits ozone when exposed to sunlight, resulting in the so-called “summer smoke” phenomenon. Photochemical smog stimulates people's eyes and respiratory system and endangers people's health and plant growth. Therefore, isopropyl alcohol is a chemical that is harmful to the environment and the human body. It is inevitable that reducing the use of isopropyl alcohol in the printing industry will reduce the use of isopropyl alcohol. the trend of.

Third, film and waste fixer. At present, the most used in printing is offset printing. In offset printing, most of the plates used for printing are printed on the photo-setter to make the PS plate to print on the machine. The film is a silver salt photosensitive material containing silver ions, and the fixed waste fixer solution also contains a large amount of silver ions. If these substances directly enter the environment, heavy metal silver ions can contaminate natural water bodies and cause environmental damage. The film base of the film is a macromolecular compound that is extremely difficult to degrade and contaminate the soil in the environment.

Fourth, plastic film. Plastic film is popular among publishers and consumers because of its folding and abrasion resistance, ability to protect prints, increased gloss, and low cost. However, plastic film cannot be degraded and becomes white pollution. The coated paper cannot be recycled. This causes waste of resources. At the same time, the use of toxic volatile solvents, such as toluene and naphthalene, in the coating process will endanger the health of workers and pollute the environment.

Fifth, oily glazing materials. The glazing process is a process for finishing the surface of printed products. After polishing, the gloss, smoothness, and stiffness of the surface of the printed product can be increased to protect the printed products and increase the appearance. However, the diluent used for oily glazing materials is mainly toluene, which is a toxic volatile substance. Inhalation of a certain amount of toluene by the human body can lead to lesions in the respiratory system and blood system. Therefore, the oily glazing process does not meet the environmental protection requirements. In particular, packaging materials such as medicines and foods, and children's toys, children's books, etc. should not use oily glazing techniques.

Sixth, plastic printing waste products. With the rapid development of the printing and packaging industry, the printing of plastics and other organic polymer materials is becoming more and more common. The plastic printing waste products produced by printing plants are a kind of solid pollutants that cannot be ignored, due to their water insolubility and extremely difficult in nature. Degradation, if directly into the environment will inevitably cause harm. If the waste is burned nearby, a large amount of toxic gases such as dioxins will be produced. At extremely low concentrations, dioxin can cause distortion in humans and animals, and it is a strong carcinogen and can seriously pollute the surrounding environment. air. Therefore, plastic printing waste must be treated properly.

Second, the basic measures for the development of green printing

First, vigorously develop and develop water-based inks, UV inks, and other new inks that require symbolic environmental protection. Water-based ink is a world-recognized environmentally-friendly printing material. Since water is a polar substance, depending on the compatibility of polar substances with polar substances, water-based inks do not contain or contain a very small amount of organic solvents. Therefore, water-based inks are used. The most important feature is the reduction of VOC (volatiles) emissions, thus avoiding air pollution, improving the printing operation environment and benefiting the health of workers. It can completely eliminate the harmful effects of some toxic and harmful substances in the solvent ink on the human body and the pollution of the packaged products. It is especially suitable for packaging and printing products with strict requirements for hygienic conditions such as foods, beverages and medicines. In addition, it not only reduces the risk of fire caused by static electricity and flammable solvents, but also reduces the residual solvent odor on the print surface.

Second, develop and promote flexographic printing. In addition to its own advantages and technological advances, one of the most important factors for flexographic printing is that it meets the requirements of environmental protection and green packaging, and can be widely used non-toxic, non-residual solvents, non-environmentally polluting aqueous inks and UV inks.

Third, develop and improve waterless offset printing and non-alcoholic printing processes. Waterless offset printing is an offset printing process without fountain solution. Because there is no fountain solution, there are no problems such as volatilization of organic compounds and environmental protection. Alcohol-free printing is the replacement of isopropanol in alcohol fountain solution with a mixture of ether, ethylene glycol and other additives. This kind of alcohol substitute has low volatility, high ignition point, no irritation, and is beneficial to the health of workers and production safety. It is an environmentally friendly printing fountain solution. For example, an alcohol substitute called Substifix HD has been developed abroad and has been extensively tested to prove that it is a substance that has no bad odor, does not harm health, and does not pollute the environment. At the same time, ink emulsification began to take more time than Isopropanol is slow, there is no ink penetrating the dampening system, printing speed is no less inferior to alcohol printing, is an economic and environmentally safe product.

Fourth, the development of filmless direct platemaking technology (dry film imaging). Dry film imaging does not require conventional exposure and rinsing of the film, and it does not require a developer. Naturally, it does not require related equipment and operating procedures. It is especially useful for imaging without the use of any chemicals. "Green" imaging technology.

Fifth, develop and develop water-based glazing processes. Plastic coating and oily coating will cause great harm to the environment. The thinner used for waterborne coating is non-toxic, odorless and non-polluting water. From the viewpoint of environmental protection and human health, waterborne coating The craft is undoubtedly advantageous.

Sixth, using environmental protection technologies to treat waste gas and waste. Collect all types of waste generated during the printing process, recycle valuable materials such as paper, and recycle waste materials such as film and plastic film that are difficult to degrade the environment. Or sanitary landfill. At the present stage, because of the process and other reasons, it is also necessary to use a variety of printing materials with pollution, such as oily ink, oily film, oily glazing, etc., and harmful and toxic gases generated during their use can pass through the air. Adsorption, absorption, catalytic combustion and other methods are used to reduce the concentration of harmful gases in the working environment, reduce the damage to workers, and reduce the pollution of harmful gases to the environment.

With the improvement of environmental protection requirements and the strengthening of people’s environmental protection awareness, vigorous research and development of environmentally friendly printing materials, improvement of printing processes, and development and promotion of environmental protection printing processes have become the subject of industry research in the 21st century. At present, China's printing industry still has a big gap compared with developed countries in terms of environmental protection technology. Therefore, it should increase investment in the research and development of printing environmental protection products and processes, and do a good job in science and technology promotion. The author believes that as long as we continue to study and practice, green printing will be popularized in China in the near future, and green printing products will go with our lives.