Formula selection and application of water-based gravure aluminum foil ink

Abstract: Water-based gravure aluminum foil ink series products adopt advanced water-soluble polyurethanes, water-based acrylic resin emulsions, styrene/acrylic resin emulsions, alcohols and ammonia solvents, water, aqueous pigments (dye) and novel water-soluble The intermediate materials such as auxiliaries are fully dispersed and ground to form a water-based ink product with tackiness and coloration. It is suitable for high speed and low speed printing on gravure printing machines. For pure aluminum foil film or aluminum film, it has good light fastness, good adhesion, excellent softness, bright and bright printing, and good after-cutting properties.

Keywords: water-based gravure aluminum foil ink, water-soluble polyurethane, styrene/acrylic resin emulsion, alcohol and ammonia solvent, printability.

Foreword

Since the reform and opening up, with the increasing development of China's printing industry, the amount of ink required by the domestic market is increasing, the variety of inks is increasing, the quality level is getting higher and higher, and the awareness of environmental protection is getting stronger. At present, the printing industry continues to develop towards high-end packaging printing and environmental protection printing. With the development of the market in our country and the improvement of the economic level, people are increasingly demanding the packaging and decoration of various products, and the packaging colors of various products are varied. In China, especially the packaging of beer, more and more aluminum foil is used to seal the bottle mouth and thin aluminum foil bottleneck labels, such as Zhujiang Beer, Blue Ribbon Beer, Tsingtao Beer, Shengli Beer, Jinwei Beer, Draft Beer and so on. With so many aluminum foil bottle-sealing and thin aluminum foil bottleneck labels, it is necessary to have special inks for aluminum foil packaging and printing. Now when printing these aluminum foil sealing and thin aluminum foil bottleneck labels, most printing companies use oil-soluble. Solvent-based gravure ink. However, organic solvents in solvent-based gravure inks generally contain toxic esters and benzenes. Even alcohol-soluble aluminum foil inks, which many people nowadays are talking about, contain esters. The ester solvents also have certain toxicity. This gives a lot of inconvenience in the application and testing conditions, especially in the export of foreign products, there are certain limitations and constraints. So we asked: Is there an entirely green and healthy ink application that is printed on such aluminum foil sealer and thin aluminum foil bottleneck labels? Yes, just like foreign water-based ink printing, China now also has water-based gravure ink applied to aluminum foil. This type of water-based gravure foil also has a unique market for this type of ink in specific packaging and printing applications, and therefore water-based gravure foil ink has emerged.

Water-based gravure foil ink is better in the printing quality, easy to print, ink film color is bright, gloss is high, frost resistance and water resistance are better, and the lightfastness is definitely better. In addition, the printed matter after printing with this type of water-based gravure ink has good cutability and excellent alkali-cooking performance, and can be applied to different depths and speeds. In the following, based on the point of view of the design and production of waterborne gravure inks, some simple analyses are made on the characteristics related to the selection and application of the waterborne gravure aluminum foil inks for the ink manufacturers and printing manufacturers to formulate and apply the inks of this type. Reference.

Classification of water-based gravure foil ink

Water-based gravure aluminum foil ink in the body of the main resin connection material generally have styrene / acrylic resin emulsion, acrylic resin emulsion and water-soluble polyurethane resin fatty acid resin solution, so the water-based gravure aluminum foil ink composition can be seen as styrene / acrylic resin emulsion System and water-soluble polyurethane fatty acid system.

The ink film of the styrene/acrylic resin emulsion system is hard and strong, and the drying speed is fast. The surface of the ink film after drying is easy to absorb water. But its low volatility odor and ink film gloss is relatively high, the ink is stable, storage time is long, the printing machine adaptability is better, the price is lower. Because the ink film is hard and brittle, its adhesion to aluminum foil is somewhat poor. Sometimes it is necessary to add a water-soluble polyurethane fatty acid resin to reduce its hardness and brittleness, increase flexibility, and improve its adhesion on aluminum foil substrates. Fastness.

The water-soluble polyurethane fatty acid system is contrary to the styrene/acrylic resin emulsion system, the ink film is soft and sticky, the drying speed is slower, and the water resistance is better than the styrene/acrylic resin emulsion system. However, a single water-soluble polyurethane fatty acid resin can not make its application on aluminum foil perfect, but also need to add some water-based non-ionic surfactants and release agents and other water additives in water-based gravure aluminum foil ink formulations. To improve the toughness of the ink film, but the added amount should be controlled, otherwise it will increase the original cost of the ink material and ink film drying after printing is poor, or even back to the phenomenon of sticking.

In fact, the styrene/acrylic resin emulsion system and water-soluble polyurethane fatty acid system water-based gravure aluminum foil ink each has its own strengths and shortcomings. In the process of doing this type of water-based gravure ink, the two components will be properly matched, complement each other, and the performance will be balanced. This will be beneficial to the type of ink on the machine printing, suitable for high and low speed printing, for pure aluminum foil film or aluminum The material film has the characteristics of good light resistance, good adhesion, excellent softness, bright and bright printing, and good post-cutting properties.

When water-based gravure foil inks are used, we sometimes use solvents such as water, alcohols, ammonia, or ethers. Based on the considerations of the health and environmental requirements and hygienic conditions of water-based gravure inks, we will comply with different requirements. The standard ink composition, there is no ether and ammonia, but also only add water as a solvent (diluent) and alcohol solvent is not added.

If the water-based gravure aluminum foil ink contains ethers and ammonia, its toxicity is also large, but due to its use of water-soluble polyurethane fatty acid resin, the solvent release is slower, and the evaporation speed of ethers and water is slower. Therefore, the residual amount of the ink film solvent after the printing of the water-based gravure aluminum foil ink will be large, that is, the ether residue will remain in the ink film. If the aluminum foil packaging material is printed on the surface ink, it can also be used, but it is generally required not to use it. Prints food packaging materials that are in direct contact with the food. Therefore, if a water-soluble polyurethane fatty acid resin is used in the water-based ink formulation, then the solvent can be added with little or no ether and ammonia to reduce the pollution and improve the health and environmental protection of the water-based ink.

If the water-based gravure aluminum foil ink only contains water, alcohol solvents and a small amount of ammonia, and no ether solvent, this is also in line with the problem of solving the slow-drying problem of water-soluble polyurethane fatty acid resin, because alcohols and ammonia are very Fast drying, the slowest dry ether (less plus good). Most of the alcohol solvents and ammonia will evaporate after the ink is printed and dried. The hygienic conditions are greatly improved. The printed products are almost non-toxic and can be compared with the energy-curable ink. The price of the water-based ink is far away. Far lower than energy-curable inks; printing equipment requirements are far simpler than energy-curing inks. However, the surface of the ink film of the water-soluble polyurethane fatty acid resin is relatively viscous and not slippery, which is mainly caused by the water-soluble polyurethane fatty acid resin because of its release properties against water and alcohol solvents. SLOW. The aqueous aluminum foil ink of styrene/acrylic resin emulsion system is inferior to the water-based aluminum foil ink of water-soluble polyurethane fatty acid resin system. The reason may be that styrene/acrylic resin reacts with water and alcohol solvents. Since the ink film contains -OH or -COOH in the ink film, it is a hydrogen bond acceptor and a distributor. Therefore, water molecules easily form hydrogen bonds with it, resulting in poor water resistance. Nonionic water-based wax emulsions are usually added to improve their water resistance (or other additives that mask -OH and -COOH are added), but their water resistance is still not ideal.

Waterborne gravure aluminum foil ink vividness

To improve the vividness of the color of water-based gravure foil ink, it is necessary to print the ink first and then overcoat a layer of water-based gloss. However, if this is done, the printing cost will be greatly increased unless a special request is given to the printer. Dare to do this. Another method is to print the color ink on the glossy side of the substrate--aluminum foil. This requires a high degree of surface treatment on the light side of the foil (generally more than 42 dynes) in order to make waterborne. The ink has a good adhesion on aluminum foil. Another is the use of water-based dye powder as the transparent water-based ink, its excellent vividness and transparency, but the use of water-based dye powder is more difficult to choose, and its price is particularly high. The most viable option now is to use a high-gloss, water-soluble acrylic polymer for use with water-based ink formulations.

The slitting property of water-based gravure foil ink

Pure aluminum foil is relatively brittle, and its flexibility is not enough. Generally, the color ink of water-based varnish or water-based gravure aluminum foil ink is to be printed, so that the flexibility of the aluminum foil can be improved and the cutting effect can be improved. Under normal circumstances, after printing water-based gravure aluminum foil ink, it is not necessary to print water-based varnish, and it also meets the requirements for slitting, that is, printing water-based varnish or color ink alone can achieve the cutting requirements. The fact that the print surface is too hard or soft is not conducive to slitting, and that the print surface is too slippery or blunt is not conducive to slitting. It is usually achieved by adjusting the content of styrene/acrylic resin emulsion in the water-based gravure aluminum foil ink. The glass transition temperature of the styrene/acrylic resin emulsion is directly proportional to the hardness of the ink film, if a single styrene/acrylic resin emulsion is not achieved. To meet the requirements, two or more different styrene/acrylic resin emulsions with different types, different glass transition temperatures, and different properties can be used to meet the requirements. The smoothness of the ink film surface can be adjusted with aqueous wax emulsion or aqueous wax powder to meet the cutting requirements. Usually also add some water leveling additives to improve the printing effect, prevent the production of orange peel, smooth ink layer to facilitate the cutting. One thing to note is that the water leveling agent should not be added, because some water leveling additives have extinction and adverse effects, which will affect the brightness and adhesion of water-based gravure foil ink printing products.

Water-based gravure foil ink freeze-thaw resistance and water resistance

The aluminum foil sealer and thin aluminum foil bottleneck labels are often used to make beer labels. In the summer, the beer is generally frozen in the refrigerator and has water droplets on the surface. Therefore, the ink film of the water-based gravure aluminum foil ink usually requires frost resistance and water resistance. . The water-based ink ink layer made of a water-soluble polyurethane fatty acid resin having a relatively low softening point has good low-temperature resistance, and the water-soluble polyurethane fatty acid resin will increase when the ink is formulated or inked. Improves frost resistance; water-based wax emulsions or aqueous wax powders also improve water resistance.

Printing Suitability of Waterborne Gravure Foil Ink

When printing, first adjust the pressure and temperature of the printing press and then start printing. When printing on the machine, it is necessary to adjust the viscosity of the water-based gravure aluminum foil ink with water or related alcohol solvent first: the viscosity of the ink should be lower when printing at a high speed, and more water and other alcohol solvents should be added; the ink viscosity should be higher when printing at low speed Add little water or alcohol solvent. The shaking of the ink should be constantly stirred to even the ink. It can also prevent the surface of the ink in the water-based gravure printing ink from being volatilized due to the volatilization of ammonia, and it is also necessary to add a suitable alcohol solvent to make up for the alcohol solvent that is easily released. To keep the ink viscosity consistent, it is best to have a circulating ink pump. Water-based inks are more likely to foam during the printing process due to the larger surface tension of water-based ink solvents (water and alcohols), and the addition of an aqueous defoamer can generally act as a defoamer.

Some prints stick together when they are put down, or the ink layer separates and sticks to the back of another layer of prints. This is adhesion because the surface of the ink layer is dry when it is dry and there is water or alcohol solvent inside. It is also possible that there are other organic amine residues that are caused by re-dissolving the ink layer in a hot and humid environment. To solve this problem, one method is to add water-based wax emulsion or water-based wax powder to prevent adhesion; the other is to use a special quick-drying solvent to dilute the ink (such as ethanol, isopropyl alcohol, etc.) to reduce the ink film dry Occurrence; or is to change other water-based acrylic resin to improve the ink water and alcohol solvent release and dryness.

Printing case analysis of water-based gravure aluminum foil ink


Our water-based gravure aluminum foil ink has just been designed, and it needs to be further improved in the practical application process. I believe that as long as the printing and actual