Printing technology for cosmetics green plastic packaging

Printing technology for cosmetics green plastic packaging

First, the green technology of gravure printing

First of all, it is necessary to develop advanced plate-making technology and replace traditional corrosion plate-making technology with advanced plate-making technologies such as electronic engraving and laser engraving;

 promote film-free electroplating engraving technology and develop computer-to-plate (CTP) technology, which can eliminate the complexity of engraving and plate-making. process, increase the speed of plate making, reduce waste liquid caused by film development, etc. A fully enclosed unit is used in the gravure printing equipment to reduce the diffusion of solvent in the workshop and improve the environmental performance of the gravure printing machine. Gravure printing in-line processing technology can save resources and is an important green and environmentally friendly process. Nowadays, the most widely used technologies include in-line glazing, in-line hot stamping, in-line die-cutting and creasing, in-line inspection, etc.

Secondly, we must promote water-based gravure inks; 

develop alcohol-soluble plastic gravure inks, that is, toluene-free inks, to achieve stupidity-free inks. Toluene-free inks are to replace the toluene in traditional plastic gravure inks with other non-toxic or less toxic substances. It is replaced by solvent and its printing performance is similar to that of traditional toluene-based ink, thereby meeting the requirements of green environmental protection. Alcohol-soluble ink has the characteristics of low odor and no benzene, which can effectively solve the problems of health damage caused by toluene-based ink and the impact of solvent residue on the quality of packaging.

Third, we must develop green composite processing technology.

 The use of adhesives with high solid content and low viscosity has become an important development direction of dry composite adhesives. Using adhesives with high solid content at the same coating amount can effectively reduce the amount of solvent used and drying load. Reduce energy consumption, reduce residual solvents, and improve production efficiency; others include the use of alcohol-soluble polyurethane adhesives, water-based adhesives, and solvent-free adhesives, etc., which can effectively reduce energy consumption, reduce harmful gas emissions, and achieve better results. Environmental requirements. Wholesale skin care bottles

2. Green technology of screen printing

First, treat waste liquid and waste gas.

The waste liquid produced during the screen plate making process contains organic emulsion particles. If dichromate is used as the photosensitive agent, it will contain chromium, so it must be treated as toxic waste liquid; mercury wastewater and acid-base waste liquid are also used in plate making factories and printing and dyeing plants. pollutants emitted. Methods for treating mercury include activated carbon adsorption, chemical coagulation, sulfide precipitation, metal reduction and ion exchange. If acid and alkali waste liquids are discharged into public water sources, the pH value of the water sources will change. In addition, acid-base waste liquid can eliminate or inhibit the growth of bacteria and microorganisms, thereby hindering the self-purification of water bodies and affecting the ecology. The treatment methods for acid-base waste liquid include mutual neutralization method and flue gas neutralization method.

The treatment of exhaust gas is also very important. On the one hand, low-volatile water-based inks or non-volatile UV inks should be used in the printing process. On the other hand, it is necessary to effectively control the exhaust gas, install a ventilation device in the printing workshop, discharge the exhaust gas in a timely manner, and burn the exhaust gas to eliminate it, or use water spraying at the exhaust outlet to purify the exhaust gas. The commonly used purification method in printing workshops is adsorption separation technology.

Second, develop new technologies and materials.

In addition to making full use of high-tech computers and other technologies in pre-press and post-press processing, like other printing methods, screen printing is also constantly absorbing and utilizing new technologies and methods in printing to improve printing quality and printing speed. reduce environmental pollution. In particular, the application of digital platemaking technology provides silk screen printing with good conditions for improving printing quality and reducing pollution.

Third, promote environmentally friendly screen printing inks.

The harm of ink in screen printing to human body is considerable. Generally, inks contain volatile chemicals. Some inorganic pigments contain heavy metal elements such as lead, chromium, copper, and mercury, and some contain the carcinogen biphenyl glue. Among the organic solvents used in printing, many are natural resins and synthetic resins, which are important components of various inks. During production, solvents enter the body through skin contact, which will damage the human body and subcutaneous fat. Long-term exposure will cause the skin to become dry and rough; if it penetrates into the skin or blood vessels, it will endanger the person's blood cells and hematopoietic function along with the blood; it will be sucked into the trachea, It spreads to other parts of the bronchi, lungs, blood vessels, and lymphatic vessels, and may even cause chronic poisoning. Wholesale skin care bottles

Currently, green inks suitable for screen printing include water-based inks, ultraviolet light-curing inks, and electron beam radiation-curing inks.

Water-based ink is a world-recognized environmentally friendly printing material. Since water is a polar substance, according to the miscibility characteristics of polar substances and polar substances, water-based ink does not contain or contains a very small amount of organic solvents. Therefore, the maximum consumption of water-based ink The characteristic is that it reduces VOC emissions, thereby avoiding the pollution of volatile organic compounds, improving the printing operating environment, and is beneficial to human health. It can completely eliminate the harm to the human body and the contamination of packaging products caused by certain toxic and harmful substances in solvent inks. It is especially suitable for packaging and printing products with strict hygienic conditions such as food, beverages, and medicines. In addition, it reduces fire hazards caused by static electricity and flammable solvents, and reduces residual solvent odors on the printed surface. UV light-curable ink has the advantages of low solvent content and no environmental pollution. It has developed rapidly in recent years. Since the energy of electron beam radiation is stronger than that of ultraviolet radiation, electron beam curing ink is not limited by the thickness of the ink layer and is safer to operate than ultraviolet light curing ink. However, this equipment is relatively expensive and it is still difficult to promote it. .

3. Green technology of flexographic printing:

The products printed by plastic flexographic printing mainly include plastic packaging for food, cosmetics, sanitary products, etc. Flexo printing is suitable for medium and low-end film products, and its specialty is low price and short production cycle. With the development of the economy and people's increasing awareness of environmental protection, flexo printing will be more and more widely used. The operating cost of using flexographic printing is much lower than that of offset printing and gravure printing machines, because the flexographic printing machine has fast start-up speed, simple operation, saves energy, and can complete many processes at one time.

Flexographic printing has widely used water-based ink printing, so it is known as the greenest printing method. However, it is still not completely pollution-free to the environment. There are still the following problems in the printing process:

First, flexographic plate washing is completed in a dedicated plate processor. 

Most developers use chlorinated hydrocarbon solvents as the main solvent, but they are toxic and highly volatile. Pay attention to the amount of water in the air when using them. The content cannot exceed the poisoning limit. In addition, when light, air, and moisture coexist, chlorinated hydrocarbon solvents will decompose to produce acidic hydrogen chloride gas, which will corrode metals. Therefore, special cleaning equipment must be used when using it. The equipment itself must be able to recover the developer for recycling to minimize pollution.

Second, during the plate making process, 

in order to remove the stickiness on the surface of the plate and enhance the inking ability of the printing plate, it is necessary to use light or chemical methods to detack the plate. The traditional chemical method is to immerse the dry printing plate in a well-prepared detackifying solution. There are two types of chemical detackification: chlorination treatment, that is, bleaching powder aqueous solution, and bromination treatment, that is, hydrochloric acid and bromide aqueous solutions. Both solutions are very harmful to the environment. The illumination method is a commonly used method now. It is completed by irradiating the bromine solution tank with ultraviolet C. Relatively speaking, it causes much less environmental pollution, but the waste liquid still needs to be properly disposed of. There is now a digital dry plate making system that uses thermal processing plates and the entire process is in a completely dry state. Since no solvent is required, environmental pollution problems caused by solvents are completely avoided.

Third, although the water-based ink used in flexographic plates has significantly reduced VOC emissions, it still hopes to minimize emissions. In addition, try to exclude pigments with high heavy metal ion content.

Fourth, there are also environmental factors in the cleaning process of the anilox roller. 

General cleaning methods include strong corrosive chemical cleaning, jet cleaning, ultrasonic cleaning, etc. The strong corrosive chemical cleaning method applies the corrosive cleaning agent evenly to the surface of the anilox roller. If necessary, wrap a layer of plastic on the surface of the anilox roller to prevent the liquid from evaporating. After the cured ink is fully softened, clean it with water or alcohol. This method has the best effect, but it will cause certain corrosion to the anilox roller and pollute the environment. The jet cleaning method is to spray the baking soda softening cleaning medium onto the surface of the anilox roller to crush the solidified ink to achieve the purpose of cleaning. This method is pollution-free. The ultrasonic cleaning method is to immerse the anilox roller into an ultrasonic cleaning pool filled with chemical cleaning liquid. The anilox roller rotates slowly, and the frequency conversion device in the pool that can send high-frequency sound waves starts to work. The solution vibrates to generate bubbles, which causes an inward explosion. Continuous inward explosive force expels the ink from the cells, this method is also very environmentally friendly.

Conclusion

The above-discussed green printing technologies commonly used in plastic packaging, other green and environmentally friendly printing methods include emerging green printing methods such as waterless offset printing technology and digital printing. They have more applications in other fields, and they need to continue to be improved and promoted in plastic packaging printing.

Vigorously developing green packaging and printing is a concrete manifestation of circular economy in the packaging and printing industry. It is an essential requirement for developing circular economy and a comprehensive, coordinated and sustainable development concept. It is a powerful measure to establish a resource-saving society and promote harmony between man and nature. Therefore, we must actively develop green plastic packaging and printing and advocate green and low-carbon production methods and lifestyles.