Packaging Printing Liquid Ink Analysis

According to ink ink rheological properties of the classification method, ink products are divided into two categories: the paste ink and liquid ink. The method of classifying inks by the printing plate type, in which the gravure ink, the flexographic ink, and most of the mesh printing inks are liquid inks. This article will focus on the status quo and development trends of gravure and flexographic inks.

The production and application of liquid ink in China is developed with the technological progress of the packaging and printing industry in China. Liquid inks have been produced in small quantities in the late 1950s. The production volume in the 1960s was still small. Its type was gravure printing ink and was mainly used by the publishing industry. From the late 1960s to the early 1970s, plastic film packaging materials began to be used in China. Followed by the ink company launched a gravure printing plastic ink, in the PE and PP surface sheet printing. In the late 1970s, water-based inks were successfully developed and put into production. In the early 1980s, flexographic printing inks began to be produced. In the late 1980s, intaglio printing plastic ink came out in China. In the 1990s, gravure printing inks developed rapidly. Since the mid and late 1970s, printing companies in China have introduced multicolor intaglio printing presses from abroad. With the increase in printing speed and the adoption of new packaging materials, the development and production of liquid inks in China has entered a new era and has now basically taken shape. The four major systems of liquid ink products: surface printing plastic ink, plastic ink printing (gravure composite plastic ink), gravure printing ink, water-based flexographic ink.

First, table printing plastic ink

In the late 1960s and early 1970s, with the adoption of plastic film as a new packaging material, the emergence of domestic gravure plastic film printing machines and plastic gravure printing inks based on polyamide resin as the main connecting material took the lead in Tianjin, Shanghai's ink company launched, the product has a high gloss, strong adhesion characteristics. After more than three decades of improvement and improvement, its quality level has basically met the needs of domestic printing companies. In addition, there are PVC plastic ink printing ink, film free processing plastic ink, silk screen plastic ink and so on.

Plastic table printing inks need to improve the quality of products are: 1 improve the coloring of ink: domestic ink coloring power is significantly lower than imported ink, this is because the concentration of domestic pigments itself is worse than the imported pigments, generally only imported 80- 90% In actual production, if the amount of pigment used is increased from the standard of 10% to 12%, although the tinctorial strength can be improved, some of the varieties of ink and ink have problems. Therefore, the pigment factory to increase the pigment concentration, ink companies need to improve the ink, is the urgent need to solve the problem of plastic ink printing. 2 to improve the ink's frost resistance: domestic ordinary plastic table printing ink, poor resistance to low temperature in the winter, the ink product is easy to jelly, in the ink bucket is not easy to pour, need to return to normal temperature conditions before use, to Printing companies have brought certain difficulties in use. This is mainly due to the low freezing point of the main link material polyamide resin of the ink. After years of exploration and practice, ink companies of all sizes can produce antifreeze inks. Specific measures are: use of low freezing point polyamide resin, adding auxiliary resin, adding antifreeze additives, etc., can all play a role in reducing the freezing point. 3 to solve the thermal adhesion: Table printing plastic ink is based on polyamide resin as the main material, and fight with other resin, to ensure the gloss of the ink and solve the heat adhesion defects. However, there are also a lot of ink manufacturers, in order to reduce costs, only one polyamide resin is used as the binder, and the quality of the polyamide resin is poor (such as the softening point is within 95°C), so the ink is printed and then printed. There are multiple disadvantages of adhesion. To solve this problem, ink manufacturers should use polyamide resins with softening points and penetration criteria (such as a softening point between 105-115°C) and a certain amount of nitrocellulose as a secondary binder. 4 Develop inks with special properties: At present, due to the wider use of inks, the requirements for inks have become increasingly stringent. Therefore, the polyolefin film inks, oil-resistant plastic inks, water-resistant and anti-freeze plastic inks, heat-resistant Plastic inks, etc., have all been researched and developed and put into production one after another. The varieties of table printing plastic inks will gradually improve.

With the improvement of human environmental awareness, "water-based ink" has become imperative. In 2000, experts and professors from the Department of Chemistry and Chemical Engineering of Sun Yat-sen University in Guangdong Province, successfully developed the "waterborne gravure plastic film printing ink" and passed the inspection of the National Quality Supervision and Inspection Center for Printing and Decoration Products. The scientific research results have been brought to market and produced. The ink has the characteristics of good adhesion fastness, good gloss, no solvent residue, etc., which can meet the requirements of environmental protection customers and export product packaging.

Second, in India plastic ink

The composite packaging printing process was introduced from Japan in the early 1980s. Large-scale rotogravure printers were also imported from Japan, and a few came from Europe. At that time, the intaglio compound plastic ink was also supplied by the Japanese ink company. Until the mid-1980s, China had its own domestic composite ink developed. In the initial stage, chlorinated rubber was used as the main connecting material, and A-block was used as a solvent to produce composite inks. The greatest advantage of this type of composite ink is its strong adhesion and high composite strength. However, due to its large amount of residual solvents and poor printability and ink properties, it has not yet formed mass production. In the early 1990s, domestic joint venture ink companies adopted European technology and process routes, using ethylene copolymers and chlorinated polypropylene as the main binder; toluene, esters, and ketones as solvents, to produce a new generation of composite inks. . Such composite inks not only have strong adhesion, excellent printing and compounding properties, but also have a great reduction in residual solvents. After years of continuous practice and improvement, the current process route has become increasingly perfect, and has become the mainstream production process of domestic composite ink. In the middle and late 1990s, some ink manufacturers in China adopted the most advanced technology route in the world, using polyurethane as the main connecting material and esters and ketones as solvents, to produce benzene-free composite inks, which are suitable for high hygiene requirements. Printing of food, medicine and other packaging. With a specific type of polyurethane as a binder, another major category of inks produced is a retort-resistant composite ink. The printed bags require cooking at 110-130°C for 30 minutes without bleeding, peeling or cracking. . At present, the light packaging ink with chlorinated polypropylene as the route, the benzene-free composite ink with polyurethane as the route, and the two-component polyurethane-based cooking-resistant compound ink can basically meet the needs of the domestic packaging and printing industry. The quantity has become saturated and stable.

Recently, domestic ink manufacturers have developed environmentally friendly water-based composite plastic inks. Aqueous composite inks mainly include waterborne acrylic and waterborne polyamide types. In general, water-based composite inks have a certain gap in terms of dryness, ink, adhesion, etc., compared with solvent-based composite inks, but we believe that with the continuous update of new materials and new technology, In use, aqueous composite inks will eventually replace solvent-based composite inks.

Third, gravure printing ink

China's gravure printing inks were first developed in the publishing and printing industry. In the 1950s, Beijing's Xinhua Printing Company and other companies introduced German multicolor intaglio printing presses to print publications such as the "People's Liberation Army Pictorial". Printing inks were all imported. In the late 1950s and early 1960s, Tianjin's ink production enterprises adopted the former Soviet Union's technical route to develop a "phenyl-engraved printing ink". This ink uses rosin-modified alkyd resin as the binder, and benzene as the binder. Solvents to produce China's first generation of gravure printing inks, replacing imported inks. The ink is mainly based on non-coated paper such as printed newspapers and stamp paper. It has the advantages of good gloss, quick dryness, and bright color, but it also has the disadvantage of poor leveling. Since the 1970s, backbone ink manufacturers across the country have successively produced "alcohol-type gravure printing ink", which is based on nitrocellulose as the main connecting material, using ethanol as the solvent, and adapting to a printing speed of 30-50 meters/. The printer is printed on a gravure printer. Printing food paper such as candy paper and popsicle paper. This is the first generation of gravure printing paper ink for packaging printing in China. In the early 1990s, the printing of cigarette packs changed from offset to gravure printing, and it developed rapidly in China. Starting from Yunnan, China introduced dozens of gravure printing paper production lines from Europe, mainly packaging cigarette packets. Due to the significant increase in printing speed, a new phase of the development of gravure printing inks in China has been set off. The improved technical route of the gravure printing ink is still based on nitrocellulose as the main connecting material. Alcohols, esters and other solvents are used to improve the drying speed of the ink to 150 m/min. This ink has the characteristics of no paste, good leveling, excellent transfer performance and thick color. Previously mainly printed uncoated paper, now mainly printed coated paper. In order to improve the printability of printing inks, it has developed towards the lithographic printing. Now domestic ink manufacturers have developed standard four-color printing inks to meet the needs of printing companies. At present, the varieties of gravure printing inks are still increasing and the quality is still rising.


Fourth, soft version of water-based ink

People made the manufacture and application of water-based inks earlier. Especially since the 1970s, due to environmental protection requirements and the shortage of petroleum raw materials, people have started to research non-solvent inks, and water-based inks have made great progress. In the beginning, dextrin, shellac, casein, and sodium natrium were used as binders to produce water-based gravure inks for general books, magazines, and corrugated papers. Their gloss and water resistance were poor, and the printing effect was not good. ideal. In the 1980s, with the development of materials science, the production of water-based inks using male-modified rosin as the main binder has become the mainstream. In the same period, domestic printing companies introduced more than a dozen flexo-printed carton production lines, and ink production companies provided them with a flexo-based water-based ink. However, the primary products of these inks still have the disadvantages of poor gloss, blistering, and poor thermal stability. Since the 1990s, China has imported nearly 100 sets of combined narrow flexographic printing presses from Europe and the United States, which has played a role in the development of water-based inks. The newly introduced production line is not like the previous flexo carton printing machine printing only the block version, but the machine has added the screen printing version. The lowest cable version of the cable has reached 150 lines/inch. Therefore, new requirements have been put forward for the tinting strength, transferability, water resistance, and re-dissolvability of the ink. The development of new water-based inks is a top priority. Since the late 1980s, domestic ink manufacturers in Tianjin, Gan Valley, and Hangzhou have developed water-based flexographic inks using acrylic solutions as a binder. In the late 1990s, water-based inks also used acrylic emulsions or colloidal dispersions as the connecting material production process, making China's water-based ink into the stage of upgrading. The quality of the ink and the quality of the solvent-based ink are almost the same, and the ink is non-toxic and non-flammable. It is green and environmentally friendly. The packaging of food, medicine, and cigarettes is the preferred ink.

Water-based inks, combined with different printing methods, can be applied over a wide range of substrates. From the perspective of the development trend of international packaging printing, water-based ink has been developed from a single carton ink to various substrates. Ink and ink will be fully developed on paper, aluminum foil, vacuum aluminized film, gold and silver cardboard, composite plastics, polymer materials (such as PE, PP, PET and other substrates), metal and other substrate printing. The above-mentioned "water-based plastic surface printing ink" and "water-based compound plastic ink" are the new varieties developed by water-based inks. In China, the three pillars of offset printing, gravure printing, and flexo printing (based on ink and wash) have formed three pillars in the packaging and printing industry, from the speed of development and the ultimate trend.