Regarding the test method of ink adhesion fastness, it has been clearly stipulated in the national standard GB/T13217.7-91 and the industry standard gravure composite plastic ink technical requirements and test methods, that is, use a silk rod to place the ink on the treated low-density polymer Scrape a thin layer on the ethylene (for composite ink, biaxially oriented polypropylene film) film, place it for 24 hours, and use 21mm wide tape (cellophane, 3-4N/220mm adhesion, natural rubber adhesive) ) pasted on the printing surface, rolled back and forth three times with a tape roller machine, and then left for 5 minutes, then peeled off the tape with a disc peeling test machine at a speed of 0.6-1.0m/s, and then put a translucent millimeter grid with a width of 20mm The paper is covered on the uncovered part, and the number of cells A1 occupied by the ink layer and the number of cells A2 occupied by the removed ink layer are counted respectively, then the adhesion fastness of the ink is A=A1×100%/(A1+A2) . The standard stipulates that the ink adhesion fastness A≥95% of the solid part is qualified. In actual production, an approximate simple test method is often used to test the adhesion fastness of the printing ink layer . That is to say, it is quickly peeled off after pasting with ordinary tape, and the ink fastness is judged according to the falling off of the ink.
But in fact, the above test method only describes one side of ink adhesion fastness. This method needs to be further improved in the following aspects: First, it fails to fully reflect the influence of the contents and external environmental conditions on the ink fastness test results, such as milk, vinegar and other irritating liquid packaging printing films in the filling The fastness of the ink layer will change ; the second is that the influence of the adhesion force between the surface of the printing ink layer and the tape on the test results and the influence of the oiled cloth on the test results are not fully considered. The printing fastness of many inks is not very high, but because the surface of the printing ink layer and the adhesive tape cannot form enough adhesion, the real printing fastness of the ink cannot be detected; the third is that the thickness of the ink layer cannot be fully reflected. 1. The influence of the internal bonding force of the ink layer on the test results. For example, sometimes when tape is used for inspection, only a certain amount of ink on the surface of the ink layer is transferred to the tape. The standard does not make a clear judgment on the fastness of the ink layer in this case Provisions.
Therefore, when determining the ink layer fastness standards and inspection methods in actual production, it is necessary to consider the influence of the above-mentioned packaging contents, environmental conditions, etc., and to communicate fully with customers and suppliers when necessary.
