The experience of aluminum foil packaging printing authenticity

With the widespread application of aluminum foil packaging and printing products, the issue of the authenticity of aluminum foil printing has caused controversy in the printing industry on several occasions. With this problem, the author has gained a lot from the communication and practice between the bosses of packaging and printing companies, especially the operators, in Shanghai, Wuxi, Suzhou, Heze, Jining, Zhengzhou, Xinxiang, and Zhenjiang. The practical experience of various factories is now integrated into this article and discussed with colleagues in the industry.

Nowadays, most packaging and printing manufacturers choose 0.001-0.009mm pure aluminum foil as the composite material for printing. For example, most of them choose pure 0.0115mm aluminum foil when printing beer trademarks. The commonly used 0.007mm aluminum foil has about 500 to 600 tiny pinholes per square meter (only when the thickness reaches 0.02mm, the pinhole will disappear). Although the thickness is different, the tensile strength is almost the same, and the moisture permeability (%/m2.24h) is not the same. In order to improve the quality of pure aluminum foil packaging printing products, it must be required to have a certain degree of mechanical properties, but also to maintain a certain degree of flexibility, but the main parameter that directly affects the authenticity rate is the strength of aluminum foil. In addition, there are process problems such as room temperature printing, normal temperature polishing, normal hole punching, embossing and slitting, flattening, no fading, no knife-cutting, trimming, and packaging. Secondly, after printing, the products must also be able to withstand high temperatures (150-180°C). Even at 180-250°C, without changing the production process, the final product requirements are not discolored, do not fade, and do not increase the normal temperature conditions of auxiliary equipment. fade. At present, it has become a pressing and urgent technical problem in the packaging and printing industry.

In addition, factors affecting the quality of packaging and printing of pure aluminum foil are die-cutting, that is, the ink film of the printing ink or the brittleness of the oil film of the post-printing coating oil will cause this failure to occur frequently. Second, die cutting does not even damage the die cutter, that is, the ink film of the printing ink or the overlying oil film of the coating oil will also directly cause the adhesion of the aluminum foil to be scrapped.

In order to solve and avoid the problems caused by the strength of the pure aluminum foil, we have found that there is a difference in the horizontal and vertical strengths after the horizontal and vertical inspection of the aluminum foil of the reel. For example: when the strength of the original aluminum foil is horizontal, the breaking force is 15.066, after printing is 15.361, the breaking strength is 1.0044, after printing is 1.024, the deformation rate is 5%, and after printing is 4.6%; and the longitudinal breaking force is 15.764, after printing, 16.576, breaking strength was 1.051, 1.106 after printing, deformation rate 3.9999%, and 4.2% after printing. Another example is the strength of the aluminum foil after embossing. The transverse tensile breaking force is 9.069 (10.25 in the longitudinal direction), the breaking strength is 0.6046 (0.6833 in the longitudinal direction), the deformation rate is 3.9999% (vertical 3.999), and the embossing pattern is different and different The number of large and small holes after the breaking force, breaking strength, the strength of the deformation rate and so on are not the same. We should have a clear understanding of the production process requirements such as packaging and decoration design, photolithography, printing and cutting, and label adhesion. For consumer users, the horizontal operation method (as the horizontal breaking force is higher than the longitudinal breaking force) can be adopted when labeling to ensure the strength of the aluminum foil printing products. It also requires our decorators, designers, and photolithographers and printers to work in the direction of the package printing according to the currently used four widths: 10 to 39mm, 39 to 130mm, 130 to 220mm, and 220 to 600mm. Cutting and labeling procedures are consistent. In short, increase the quality rate in the reduction of scrap rate and reduce the cost of aluminum foil packaging printing.

In addition to the above-mentioned matters needing attention in the process flow, we can not ignore the embossing (depth of embossing and pressure, punch size, quantity is only a general indicator) equal pressure process.

The quality of the inks used in printing, the quality of the varnishes, and the temperature resistance should be strictly referenced to the technical parameters of these products, and the importance of pre-press production (in ambient temperature, ambient humidity, thickness of printed foils, etc.) The actual technical parameters under the conditions of width and printing speed, etc. can be used as the basis for our bulk packaging and printing products. Only by strictly controlling the quality of aluminum foil in the packaging printing process can we achieve a high quality rate.

Liu Jiaju

Source: China Packaging 2005/2