Green Plastic Ink: Grasp the Opportunity and Face it Concisely (I)

It is the responsibility of the world's ink workers to develop new pollution-free environmental protection inks. The ink produced using water as a solvent is non-flammable, non-explosive, non-toxic, and tasteless. In the process of production and use, it does not cause any damage or pollution to the human body and the environment. It is the latest and most environmentally friendly printing ink.

At present, the daily necessities, food, medicine, etc. are inseparable from the packaging, and most of these packages use gravure printing, according to China's ink production 260,000 tons, gravure accounts for about 30% of the share, that is, China gravure printing all kinds of packaging The consumption of ink is more than 70,000 tons. It beautifies people's lives and brings people visual enjoyment. However, it also contaminates the air at a large scale. It prints volatile solvents for every kilogram of ink, including the solvent in the ink and the diluent used for printing. At 1 kg or more. In China, 70,000 tons of gravure printing ink is printed every year, and 70,000 tons of organic solvents are also volatilized on the sky, which also causes direct damage to the printing operator's body. No matter what kind of printing method is used, what is the substrate, as long as the solvent ink is used for printing, there must be solvent residue. The highest limit of the solvent residue of the packaging material from the country is from 2 mg per square meter of the drug standard to the plastic composite bag. The total amount of solvent residues is 8 milligrams per square meter. The residual solvent will cause food contamination. How can we do both printing and environmental printing? Only the use of water-based printing ink can fundamentally solve the problem.

Through the persistent efforts of some ink manufacturers in China over the past decade and the sincere cooperation of printing companies, the technological level of plastic environmental protection ink has reached or exceeded the advanced level of similar products in the world. Some products can only be seen in China. Such as gravure gold, gravure plastic composite ink and so on. And some gravure other plastic ink: such as PVC wallpaper ink, soft plastic ink and so on. Some foreign countries, China has a lot of ink manufacturers can also produce the same, with the same quality, and even the performance of imported ink over the product. Although current ink paintings still have some problems. If the printing process is quick-drying, it can easily cause plug printing. However, as long as the printing company slightly changes the operating procedures, the ink manufacturer can make some adjustments. These environmentally-friendly plastic inks are gradually accepted by the market with their unique performance and low cost, and are growing at a high rate. It can be said that the current plastic ink products can completely replace some of the same type of ink, and can meet the needs of the printing industry.

At present, there are several types of environmental protection inks commonly used in the printing market, such as alcohol-soluble inks, UV-curable inks, and water-based printing inks. In fact, whether or not the environmental protection ink mainly depends on whether the product causes pollution to the environment during the production process, whether it causes damage to the production operator's body, on the other hand, whether the product itself contains VOCs, what percentage is it, and so on. The alcohol-soluble inks on the market today are not real, 100% alcohols used as solvents, it is more or less the use of some lipids or other types of solvents as diluents. The definition of environmentally-friendly ink and wash, some economically developed regions and countries are based on the percentage of alcoholic solvents per Kg of ink, and generally no more than 5% of environmental protection inks, which are currently used in the market. The vast majority of printing inks are UV-cured UV inks (other than water-based UV inks) that have different degrees of contamination, solvent types, including what people consider environmentally friendly. They also incorporate a certain amount of ink in the production formula. The organic solvents that are harmful to the human body are only a lot less solvent than ordinary solvent-based inks. Strictly speaking, this is not an environmentally friendly ink. The real water-based environmental printing ink uses only water as the solvent in the production process. Even if alcoholic solvents are contained within 5%, they must be edible alcohols (because ethanol is not included in VOCs), and cannot be methanol, isopropyl alcohol, etc. In order to keep the residual solvent content of printing products to a minimum, Only in this way can the printed matter meet the requirements for the safety of food and medicine packaging in any region or country.

The use of ink printing, we must first understand its various properties, and then according to the actual situation of the company can use good ink.

First, the printing speed:

The printing speed has a bearing on the output of Flexible Packaging companies. Since ink is used as a solvent for water, its drying rate is fixed. Even if solvents such as alcohols are volatilized faster than water, the printing speed is only slightly faster. This is particularly different from solvent inks. The ink is adjusted to the desired printing speed by adjusting the volatilization rate of the solvent. However, there is a limit to how the solvent ink is adjusted. In order to print at a higher speed, it is still necessary to adjust the printing press. Drying equipment to match. The ink is also relied on external drying equipment to adjust the printing speed, that is to say, the same water-based compound ink, on the gravure printing machine of different drying equipment, it can be 40 meters to 200 meters per minute or more per minute. With high printing speeds for printing, there is no distinction between high, medium, and low speed printing inks.

Second, the PH value of ink:

The PH value of the ink, the PH value of the ink at 8.5, its fluidity, gloss to achieve the best, but in the printing process, within one hour, due to the volatilization of the alkaline solution, the ink viscosity will increase rapidly, gloss If it drops, the fluidity becomes worse, and a large number of unqualified products will appear. In this case, the PH value must be adjusted, the amine solvent must be added, and during the printing process (within one hour), continuous testing (with the pH meter) should be performed. Inadvertently, waste products will appear, and the entire printing shop is full of unpleasant odors, and such products are considered poor in printability. If the PH value of the ink is between 7-8, the stability of the ink is the best. The user can add pure water as a solvent to adjust the viscosity. In the printing process, no PH regulator is needed.

Third, adhesion

With plastic ink printing, in addition to paper, PVC, aluminized film, metal foil, etc., the rest of the plastic substrates need to be surface treated, the most desirable surface treatment is above 42 dyne, because the ink is made of water The surface tension of the solvent and water is about 72 dyne, so the surface tension of the produced ink is slightly higher than the surface tension of the ink, but as long as the surface treatment of the substrate reaches the specified factor, on the flexographic printing, the printing Stoppage detection on the way, its adhesion is better than the adhesion of the ink. Intaglio printing depends on the drying equipment on the printing press. If the drying equipment is good, the ink adhesion and the adhesion of the ink are the same after the printing is finished. However, the drying equipment is slightly inferior. The effort will be a little worse than the ink, because the volatilization of water is slower than the solvent under the same dry conditions, also known as not dry, the dry time of the ink is about 16-18 hours, and the running time of the ink is about In about 24 hours.

Fourth, gloss, brightness, wear resistance

The brightness problem, whether it is ink or ink, is not related to the production process and the type of ink. However, in daily work, it is often asked whether the color brightness of the ink is lower than that of the ink. In fact, this is the cause of the brightness of the pigment itself. . Ink manufacturers will include this test in their routine tests when selecting pigments. For example, most printing companies consider the reddish and bright red of the yellowish phase to be brighter. In fact, each printing site in each region is With its own favorite or popular colors, each ink factory has a variety of different brightness, transparent or translucent colors, so the brightness of the ink and the brightness of the ink without any difference.

Gloss and abrasion resistance generally refer to the basic requirements for printing ink or ink when printing on a gravure surface. The performance of ink in this area is far better than ink. If the gloss of the table printing ink is about 70 degrees at a 60 degree angle, the anti-sticking phenomenon will occur under a certain temperature and pressure. When the gloss of the ink is at a 90 degree angle of 60 degrees, it is not under the same conditions. There will be anti-sticking, ink wear resistance is higher than the surface printing ink (except for the two-component exception). The abrasion resistance of common surface ink and the water-based surface ink are tested under the same conditions. The ink will show traces (complete decolorization) when it is rubbed for the second time, and the ink will not appear until it reaches the ninth rub. Traces (standard for ten times). Therefore, the gloss and abrasion resistance of environmental protection inks are superior to inks.