Packaging of aluminum foil printing process and characteristics
The brief process is: aluminum foil unwinding → gravure printing → drying → coating layer → drying → coating layer → drying → aluminum foil winding. Throughout the production process, the surface quality of the gravure printed text pattern and the heat seal strength to be achieved with the adhesive layer, the adhesion of the protective layer and its drying temperature and the speed of the coating machine operation, the tension control, Need to be strictly grasped. Therefore, in the "pharmaceutical packaging with aluminum foil" national standards for the printing of medicinal aluminum foil surface quality requirements are clear, the protective layer, the performance of the adhesive layer are also physical and chemical indicators, so as to protect the medicinal PTP aluminum foil has a good barrier , Health safety, heat sealing and good physical and mechanical properties. To PTP aluminum foil printing coating production process to achieve the above requirements of the performance, still need to be familiar with the application of raw material properties, and in the operation process should pay attention to the following questions:
1. Master the characteristics of aluminum foil and printing inks
PTP aluminum foil used in the production of raw materials for the industrial pure aluminum foil, the general requirements of the thickness of 0.02mm, tensile strength of 98kPa, breaking strength of 90kPa, the surface clean, flat, no wrinkles, no indentation damage, no film fluorescent material, Surface wetting tension of not less than 32. The need for medicinal aluminum foil pinhole is 0.1-0.3mm diameter pinhole not more than 1 / m2. As the pinhole in the aluminum foil is penetrating defects, drugs by oxygen, water vapor and light intrusion will reduce the efficacy or deterioration, so the requirements of the pinhole is very strict; another aluminum foil thickness if the required deviation (if the deviation ( 10%), the adhesive layer and the protective layer of the coating will have an impact, need to attract the attention of the operator.
Aluminum foil printing ink is currently divided into two categories: one for the polyamide-based ink. This ink has a good adhesion to all kinds of substances, dispersibility, gloss, abrasion resistance, solvent release is good, soft, and more used for printing plastic film. When used in the printing of aluminum foil materials, the excellent performance of the ink can be expressed, and its heat resistance can meet the requirements of aluminum foil printing. The other is based on vinyl acetate vinyl acetate copolymer resin / acrylic resin as the main component of the aluminum foil special ink, its holding point is bright color, high concentration, and aluminum foil adhesion is particularly strong, with good transparency, but As for the gravure printing, the solvent volatile, for the use of medicinal PTP aluminum foil printed sheet is likely to cause the intaglio roll ink in the ink dry, deposition, paste paste phenomenon. Therefore, it is necessary to pre-treat the deposition of the ink by freezing the necessary conditions by stirring or increasing the temperature (water bath). If the ink storage time is too long, the ink will appear deposition, resulting in the upper layer of ink resin solution, the lower pigment, the upper color light, the lower color deep, should also be used after mixing.
2. The amount of solvent added to the ink should be appropriate
When the viscosity of the ink needs to use a large number of diluents diluted, should be added side of the diluent while stirring, so that the diluent evenly distributed throughout the ink. The degree of measurement is between about 20-30 s. Indoor temperature and humidity, the impact on the ink concentration, it is best to use the ink concentration detector to determine the amount of solvent added, and according to the temperature and humidity changes, every predetermined time to determine the concentration of ink. The use of gravure printing and printing of aluminum foil products, the ink concentration is too low, will cause the printed text pattern color is not bright, reticulate paste paste phenomenon; ink concentration is too high, the map will produce cracks, not only waste ink, and Easy to cause the printing surface is not smooth, not beautiful. In addition, the optimum ink is selected according to the speed of the aluminum foil printing coater and the depth of the ink in which the gravure roll is printed.
3. Adhesives should meet the requirements
PTP aluminum foil adhesive is coated on the inside of the aluminum foil, and its role is to make aluminum foil and pharmaceutical PVC hard film can be a strong hot press, so that the plastic chip blister drug separated from the outside world, to make the drug sealed purpose. In the process of loading the drug for heat sealing, the adhesive layer is activated by the hot pressing action, which is firmly bonded with the PVC plastic hard film as a whole, which requires the adhesive layer and PVC resin should have good heat sensitivity and with the substrate Of the compatibility.
4. The temperature and time should be mastered during the printing process
Printed graphic and adhesive layer and the protective layer in the coating process are required to dry, aluminum foil surface coating in the dry need to have a process, it needs to stay in the equipment drying time for a certain time, depending on the coating mechanical winding The size of the speed and the selection of the temperature within the bunker both should maintain the corresponding relationship. As the thickness of aluminum foil material is different, physical and mechanical properties are different, and the material in the equipment running when the thermal expansion, shrinkage, extension also have some differences, it should not stay at a very high temperature too long, otherwise the aluminum foil But also prone to wrinkle and surface discoloration phenomenon. General bake channel temperature control in 170-210 ℃ is appropriate.
5. Printing coating speed, coating tension and coating thickness and bonding quality analysis
The thickness of the adhesive layer during the printing and coating process has a great influence on the adhesion degree of the plastic PVC hard sheet, the adhesive layer is too thin and the hot pressing PVC sheet will reduce the fastness of the adhesive due to the lack of material. Layer coating is too thick, not only increase the cost, and dry time to be lengthened, so need to control in the appropriate thickness range. The coating thickness of the adhesive layer is affected by the concentration of the adhesive, the coating tension, the coating speed, and the number of the anilox rollers. In the case of the shape, depth, the number of inches per inch and the line pressure between the two rollers, the greater the adhesive concentration, the smaller the coating tension, the faster the coating speed, the thicker the coating The The thickness of the adhesive layer is therefore generally adjusted by the concentration of the adhesive and the tension of the coating machine. Different types of aluminum foil on the adhesive layer thickness requirements are also different, the general coating thickness should be controlled at 3.5-7.0mm is appropriate. In the aluminum foil printing coating, the machine speed, temperature, tension between the three are related to each other, but also contain each other, between them with good or bad, directly related to the quality of aluminum foil printing coating.