After China's accession to the WTO, the domestic packaging and printing industry is facing a new development situation, which has both challenges and opportunities. The printing industry is developing from the original pure manufacturing to the information dissemination and increasing the added value of packaging products. With the demand for gentrification, personalization, anti-counterfeiting and environmental protection, packaging and printing companies should find a favorable market space in the new market, and do other people's design, processing, and development of new technologies. Adapt to market demand.
Cigarettes are high-value-added products and are targets of counterfeiters. Therefore, most cigarette labels and special brand cigarette labels have basically adopted anti-counterfeiting technology. Qiaotong has accumulated unique features in the design, printing, and anti-counterfeiting of cigarettes, achieving the comprehensive purpose of “new, extraordinary, special, beautiful and anti-counterfeiting”. In addition to anti-counterfeiting technologies such as anti-counterfeiting inks, holographic positioning stamping, and other anti-counterfeiting technologies, cigarette marking also features articles on the combination of cigarette marking design and new processes, new materials, and special printing processes, such as soft paper and paper jams. Positioning hot, gravure reverse printing, etc., in order to improve the design, printing difficulty, to achieve the effect of anti-counterfeiting tobacco labels, but also improve the quality of cigarette labels.
Water-based inks start a new era of cigarette marking
Water-based ink refers to a volatile ink that uses a part of alcohol as a solvent. The ink is dried as the water evaporates. The printing process has no pollution to the environment. The water-based ink is not toxic to the human body, and it is not easy to burn. The water-based ink is environmentally safe. The advantage is that when many paper products are printed, they can be designed to emit low VOCs or zero VOOs. With the world's attention to environmental protection, Jinjia Group launched the printing of environmental protection cigarettes at the beginning of this century. Water-based inks developed jointly with ink suppliers have been successfully put into production, which has opened up a new era of environmental protection for domestic cigarette printing.
In the use of gravure solvent inks, alcohol inks, and water-based inks, Jing Jia Group directly challenged water-based inks, led the development of water-based ink cigarette markings in China, completely changed the performance of inks, and used water and alcohol as diluents. The cost of solvent is saved, the environmental protection level is improved, and the customer's needs are met. First of all, Jingjia Group provided the “New Pride Seven Wolfs” for Fujian Longyan Cigarette Factory and became the leader of domestic water-based inks in cigarette label printing. Solvent-based inks also use a volatile dry method, but there is a large amount of volatile organics.
As international crude oil prices have remained high, the price of downstream chemical products has been rising all the way. In the past, solvent-based inks lost their price advantage. The amount of solvent used is calculated as 100% of the amount of ink, then the solvent cost of the solvent-based ink increases to 4,000 yuan/ton-5,000 yuan/ton. Considering that the drying requirement of the water-based ink is higher than that of the solvent-based ink, the coating amount of the water-based ink is less than The solvent-based ink is 15% to 20% less than the average of the three. Even if the surface price of the water-based ink is 5,000 yuan more than the solvent ink, the actual use cost is still lower than the solvent-based ink.
First, the relationship between aqueous ink PH value and viscosity
Viscosity is closely related to the fluidity of aqueous inks. The decrease of the PH value of the water-based ink directly affects the decrease of the ink activity and the solubility of the resin, resulting in an increase in the viscosity of the ink, which may cause the printing plate to dry up, thereby causing problems such as failure of the printing plate and dropping of dots. Conversely, if the pH value of water-based ink is high, the alkalinity is strong, and the resin dissolves too much, the pigment and the binder may separate, the ink fluidity will increase, leading to unclear printing dots, agglomeration, etc., and the ink will not dry easily (rotary printing The machine easily sticks to the paper roll).
In actual printing, when the PH value is between 6.0 and 7.0, the ink will have a delamination phenomenon, and the printing phenomenon will occur when printed. When the pH is between 7.0 and 8.5, the ink system becomes unstable and the viscosity of the ink increases, resulting in poor transfer, dry printing, and dropping, and the color intensity of the printed matter decreases (black ink is the most obvious). When the PH value is between 8.5 and 9.1, the water-based ink has good fluidity, the ink viscosity is suitable for printing needs, has good wettability and spreadability to the substrate, and the ink layer also has good drying properties. PH value of 9.1 ~ 11.5, a large number of foam in the ink tank, the ink viscosity has a significant reduction, resulting in slow drying rate, water resistance becomes worse, the dot gain rate increases, the footprint is not clear, agglomerate, trademark The standard barcode bar increases. At the same time, due to the strong alkaline ink, the properties of the pigment may be damaged, and the ammonia odor remaining in the mature aqueous ink print after the end of the process is used. Therefore, the pH of water-based ink should generally be controlled between 8.5 and 9.1.
Second, the relationship between aqueous ink hue and PH value
The pigment is the main factor that determines the color of the ink. It should be an inert substance. Its chemical stability determines the color rendering effect of the pigment. The chemicals that the ink is usually exposed to are nothing more than acids, alkalis, salts, water, corrosive gases, organic solvents (the ink tank is not clean), and these factors can affect the hue of the ink. Although the pigments used in water-based inks all have good alkali resistance, generally speaking, regardless of the choice of pigments, if the pH value of the ink is too high and the alkalinity is too strong, it will have more or less influence on the pigments and thus affect the pigments. The hue of the ink, so should try to avoid the PH value of the ink is too high. If the PH value is too high, the color will become lighter, and poor transfer will occur. Conversely, the solubility of the alkali-soluble resin will decrease, the viscosity of the ink will increase, the printing ink film will be thicker, and the color density of the ink layer will also be high. . Of course, if the pH value of the ink is properly controlled (between 8.5 and 9.1), the pigment will be thoroughly dissolved, the dispersibility will be good, and the hue will remain normal.
Third, the relationship between water-based ink gloss and PH value
The glossiness of water-based ink is mainly related to the thickness of the ink film, the glossiness of the linking material, the transparency and fluidity of the ink, the particle size of the pigment, the resin content, and the drying speed of the ink. Because the change of ink PH value will affect the thickness of the ink layer, fluidity, drying speed, and then affect the gloss of the ink. In addition, the solubility of the alkali-soluble and dispersion-type resins in the aqueous ink, the size of the pigment particles, and the degree of polymerization are also related to the pH of the ink. In the conversion of solvent-based inks and aqueous inks, a glossy varnish was directly selected. Only one varnish can reach the brightness of the solvent-based ink twice, greatly reducing production costs.
Fourth, water-based ink printing environment and solutions
In actual production, the working environment of the printing shop requires relatively strict temperature and humidity. When the temperature is higher than 26.5°C, the volatilization of ammonia in the ink is accelerated and the pH value decreases. A suitable amount of pH adjustment solution may be added in advance to the aqueous solvent: during the printing process, the printing ink is extracted at regular intervals or when the hue of the printed product changes. If the PH value is lower than 8.5, the pH adjustment solution may be added in an appropriate amount. When the pH value is higher than 9.1, hot air and hot water may be suitably used to heat the ink, so that the alkaline substance in the ink is volatilized, thereby lowering the PH value of the ink. Do not reduce the pH by adding acidic substances. Doing so may cause deterioration of the ink. It is generally believed that the ambient temperature of the workshop is maintained at 19°C to 25°C and the relative humidity is controlled at 55% to 65%.
The current research focuses on the stability of the water-based ink PH value. Ink manufacturers must develop water-based inks with stable PH values during the printing process. That is, there is no need to detect and adjust the pH value in printing; re-dissolvability is another key area of research. In the process of ammonia volatilization, the resin tends to solidify and even adhere to the printing plate. To this end, we appeal to water-based ink suppliers and do their utmost to research and develop high-quality water-based inks that are convenient for printing companies.
Yunnan Qiaotong Packaging & Printing Co., Ltd. Wen Jie Zhang Xuejun
Source: Ke Yin Media - "Printing Technology - Packaging and Printing"
