Current situation and development of the hottest l

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Current situation and development of liquid ink for packaging and printing


according to the method of classifying ink according to its rheological properties, ink products are divided into two categories: paste ink and liquid ink. The method of classifying inks according to the type of printing plate. Among them, intaglio inks, flexo inks and most hole inks belong to liquid inks. This paper will focus on the status and development trend of gravure ink and flexographic ink

the production and application of liquid ink in China has developed with the technological progress of packaging and printing industry in China. Liquid ink has been produced in small batches in the late 1950s, but the production volume is still small in the 1960s. Its variety is gravure printing ink, which is mainly used by the publishing industry. From the late 1960s to the early 1970s, plastic film packaging materials began to be used in China. Then the ink enterprises launched gravure surface printing plastic ink to print single sheets on the surface of PE and PP. In the late 1970s, water-based inks were successfully developed and put into production. In the early 1980s, flexographic surface printing plastic inks began to be produced. In the late 1980s, gravure printing plastic ink came out in China. In the 1990s, gravure printing ink developed rapidly. Since the middle and late 1970s, Chinese printing enterprises have successively introduced multicolor gravure printing machines from abroad. With the improvement of printing speed and the massive adoption of new packaging materials, the development and production of liquid ink in China has entered a new era. Up to now, four systems of liquid ink products have basically formed: surface printing plastic ink, internal printing plastic ink (gravure composite plastic ink), gravure printing paper ink and water-based flexographic ink

I. surface printing plastic ink

in the late 1960s and early 1970s, with the adoption of plastic film, a new packaging material, and the emergence of domestic gravure plastic film printing machines, plastic gravure ink with polyamide resin as the main connecting material was first introduced in ink enterprises in Tianjin and Shanghai. The products have the characteristics of high gloss and strong adhesion. After more than 30 years of improvement, its quality level basically meets the needs of domestic printing enterprises. In addition, plastic surface printing inks include PVC plastic ink, film free plastic ink, silk plastic ink, etc

the works that need to improve the product quality of plastic surface printing inks include: ① improve the coloring power of inks: the coloring power of domestic inks is significantly lower than that of imported inks, because the concentration of domestic pigments is lower than that of imported pigments, which is generally only% of imported pigments. In actual production, if the usage of pigments is increased from 10% of the standard to 12%, although the coloring power can be improved, the inkability of some varieties of inks has problems. Therefore, in order to improve the pigment concentration of pigment factories, ink enterprises need to improve the inkability, which is an urgent problem to be solved for surface printing plastic inks. ② Improve the frost resistance of ink: domestic ordinary plastic surface printing ink has poor low temperature resistance in winter. The ink product is easy to be gelatinous and is not easy to pour out in the ink bucket. It needs to be recycled under normal temperature before use, which brings certain difficulties to printing enterprises. This is mainly due to the low freezing point of polyamide resin, the main connecting material of the ink. After years of exploration and practice, large-scale ink enterprises can produce antifreeze ink. The specific measures are: selecting low freezing point polyamide resin, adding auxiliary resin, adding antifreeze additives, etc., which can reduce the freezing point. ③ Solve the problem of thermal adhesion: the surface printing plastic ink uses polyamide resin as the main connecting material and other auxiliary resins to ensure the gloss of the ink and solve the problem of thermal adhesion. However, there are also many ink production enterprises. In order to reduce costs, the connecting material only uses polyamide resin, and the quality of polyamide resin is poor (such as the softening point is within 95 ℃), so the ink after printing causes the disadvantage of multiple adhesion of prints. To solve this problem, printing ink manufacturing enterprises should choose polyamide resin with qualified softening point and penetration index (such as softening point between ℃), and use a certain amount of nitrocellulose as secondary connecting material. ④ Development of inks with special properties: at present, due to the increasingly wide range of use of inks, the requirements for inks are becoming more and more strict. Therefore, the system has excellent control, high stability, stable and reliable operation, fast response, low noise inks, etc. it has been developed and put into production successively, The varieties of surface printing plastic inks will gradually become perfect

with the improvement of human awareness of environmental protection, "oil ink" is imperative. In 2000, an expert professor from the Department of chemistry and the school of chemical engineering of Sun Yat sen University in Guangdong successfully developed the "water-based intaglio plastic film surface printing ink", which has passed the inspection of the national printing and decoration products quality supervision and inspection center. Now the scientific research achievements have been introduced to the market. The produced ink has the characteristics of good adhesion fastness, good gloss, no solvent residue and can meet the requirements of environmental protection customers and export product packaging

second, the printing process of composite packaging with plastic ink inside was introduced from Japan in the early 1980s. Large rotary gravure printing machines are also mostly imported from Japan, with a few from Europe. At that time, intaglio composite plastic inks were also mostly supplied by Japanese ink companies. It was not until the mid-1980s that China developed its own domestic composite ink. In the initial stage, chlorinated rubber was used as the main connecting material and methyl benzene was used as solvent to produce composite ink. The biggest advantage of this kind of composite ink is its strong adhesion and high composite strength. However, due to its large amount of residual solvents and poor printing performance and inkability, it has never formed mass production. In the early 1990s, domestic ink joint ventures adopted European technology and process routes, with ethylene copolymers and chlorinated polypropylene as the main connecting materials; Evonik is committed to providing high-quality products and services for the acrylic acid industry with toluene, esters and ketones as solvents to produce a new generation of composite inks. This kind of composite ink not only has strong adhesion, excellent printing and composite properties, but also greatly reduces its residual solvent. After years of continuous practice and improvement, this process has been improved and has become the mainstream production process of composite ink in China. In the middle and late 1990s, some domestic ink production enterprises used the world's more advanced technical route to produce benzene free composite inks with polyurethane as the main connecting material and esters and ketones as solvents, which ensured the consistency and speed of systematic sampling. They are suitable for the printing of food, drugs and other packaging with high health requirements. Another type of printing ink produced with a specific type of polyurethane as the connecting material is the cooking resistant composite ink. The printed packaging bags are required to be cooked at a high temperature of ℃ for 30 minutes without color seepage, peeling and cracking. At present, the light packaging ink based on chlorinated polypropylene, the benzene free composite ink based on polyurethane and the cooking resistant composite ink based on two-component polyurethane can basically meet the needs of the domestic packaging and printing industry, and the variety and quantity have become saturated and stable

recently, domestic ink manufacturers have developed environmentally friendly water-based composite plastic inks. Water based composite ink mainly includes water-based acrylic acid type and water-based polyamide type. In general, there is a certain gap between water-based composite ink and solvent based composite ink in terms of dryness, inkability and adhesion. However, we believe that with the continuous updating and use of new materials and new technologies, water-based composite ink will eventually replace solvent based composite ink

III. gravure printing ink

gravure printing ink in China was first developed in the publishing and printing industry. In the 1950s, Xinhua printing factory and other enterprises in Beijing introduced German multi-color gravure printing machines to print publications such as PLA pictorial. Printing inks were all imported. In the late 1950s and early 1960s, the ink manufacturing enterprises in Tianjin successfully developed "phenyl Photocopying ink" using the technical route of the former Soviet Union. The ink used rosin modified alkyd resin as the connecting material and benzene as the solvent to produce China's first generation gravure printing paper ink, which replaced the imported ink. The ink is mainly non coated paper such as printing and painting newspaper and stamp paper. It has the advantages of good gloss, fast drying, bright color and so on, but it also has the disadvantage of poor leveling. Since the 1970s, the backbone ink production enterprises all over the country have successively put into production the "alcohol type intaglio printing paper ink", which uses nitrocellulose as the main connecting material and ethanol as the solvent, and is suitable for printing on the intaglio printing machine with a printing speed of meters/minute. In order to slow down the development of the rubber industry, the resources faced by it are unsustainable and effectively solve the haze weather printing. This is the first generation of gravure printing ink used for packaging and printing in China. In the early 1990s, cigarette box printing changed from offset printing to gravure printing, which developed rapidly in China. Since Yunnan, China has introduced dozens of gravure printing paper production lines from Europe, mainly printing cigarette box packaging. Due to the remarkable improvement of printing speed, a new stage of the development of gravure printing ink in China has been set off. The technical route for the improvement of gravure printing ink this time still uses nitrocellulose as the main binder, alcohols, esters and other solvents, and the drying speed of the ink is increased to 150 m/min. This ink has the characteristics of no paste, good leveling, excellent transfer performance and thick color. Previously, non coated paper was mainly printed, but now coated paper is mainly printed. In order to improve the printability of paper printing inks and develop to hierarchical printing, domestic ink manufacturers have developed standard four-color printing inks to meet the needs of printing enterprises. At present, the varieties and quality of gravure printing ink are still increasing

IV. flexo water-based ink

people have made and applied water-based ink at an early time. Especially since the 1970s, due to the requirements of environmental protection and the shortage of petroleum raw materials, people began to study non solvent inks, and water-based inks have made great progress. At first, dextrin, shellac, casein and sodium lignate were mainly used as connecting materials to produce water-based intaglio ink, which was used for the printing of general books, magazines and corrugated plates. Its gloss and water resistance were poor, and the printing effect was not ideal. In the 1980s, with the development of material science, the production of water-based ink based on Maleic modified rosin as the main binder has become the mainstream. In the same period, domestic printing enterprises introduced more than ten flexographic printing carton production lines, and ink manufacturers produced flexographic water-based inks for them. However, the primary products of these inks still have the disadvantages of poor gloss, easy foaming and poor thermal stability. Since the 1990s, China has imported nearly 100 combined narrow width flexographic printing machines from Europe and the United States, which has promoted the development of water-based inks. Unlike the previous flexographic carton printing machine, which only printed square plates, the newly introduced production line increased the printing of line plates. The lowest line has reached 150 lines/inch. Therefore, new requirements are put forward for the coloring power, transfer printing, water resistance and re solubility of ink. It is urgent to develop new water-based ink. Since the late 1980s, domestic ink manufacturers in Tianjin, Gangu, Hangzhou and other places have developed water-based flexographic inks with acrylic solution as the connecting material. here we are

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