Generally, the requirements for pharmaceutical packaging are relatively high. In the printing process of aluminum foil for pharmaceutical packaging, industry professionals have summarized several precautions based on their own experience for your reference. The brief process flow of aluminum foil printing for pharmaceutical packaging is: aluminum foil unwinding→gravure printing→drying→coating protective layer→drying→coating adhesive layer→drying→aluminum foil winding. During the whole production process, the following issues should be paid attention to.
1. Master the characteristics of medicinal aluminum foil and printing ink
The raw material used in the production of pharmaceutical PTP aluminum foil is industrial pure aluminum foil, generally requiring a thickness of 0.02mm, a tensile strength of 98kPa, a burst strength of 90kPa, a clean, smooth surface, no wrinkles, no indentation damage, and no fluorescent substances in flakes. The surface wetting tension is not less than 32. The requirement for the pinhole degree of medicinal aluminum foil is that the pinholes with a diameter of 0.1-0.3mm are not more than 1/m². Since the pinhole in the aluminum foil is a penetrating defect, the medicine will be reduced or deteriorated by the intrusion of oxygen, water vapor and light, so the requirements for the pinhole degree are very strict; in addition, if the thickness of the aluminum foil exceeds the required deviation ( 10%), it will affect the coating amount of the adhesive layer and protective layer, and the attention of the operator should be aroused.
Printing inks for pharmaceutical packaging aluminum foil are currently divided into two categories: one is polyamide inks. This kind of ink has good adhesion, dispersibility, gloss, abrasion resistance, good solvent release and softness for printing various substances, and is mostly used for printing plastic films. When used in the printing of aluminum foil materials, the excellent performance of this kind of ink can be displayed, and its heat resistance can also meet the requirements of aluminum foil printing. The other is special ink for aluminum foil with vinyl chloride vinyl acetate copolymerized resin/acrylic resin as the main component. It is characterized by bright color, high concentration, strong adhesion to aluminum foil, and good transparency. During gravure printing, the solvent has a high volatility, and when it is used for the surface printing of pharmaceutical PTP pharmaceutical aluminum foil, it is easy to cause ink drying and deposition in the ink hole of the gravure roller, resulting in paste phenomenon. Therefore, it is necessary to carry out necessary pretreatment on the deposition and freezing of the ink, and the method is to stir the deposited and frozen ink or increase the temperature (water bath). If the storage time of the ink is too long, the ink will be deposited, resulting in more resin solution in the upper layer of the ink, more pigment in the lower layer, the color of the upper layer is light, and the color of the lower layer is dark. It should also be stirred evenly before use.
2. The amount of solvent added to the medicinal aluminum foil ink should be appropriate
When the ink with high viscosity needs to be diluted with a large amount of diluent, it should be stirred while adding the diluent so that the diluent is evenly distributed throughout the ink. The measurement of the product degree meter is about 20-30s. Indoor temperature and humidity affect the ink concentration. It is best to use an ink concentration detector to determine the amount of solvent added, and measure the ink concentration at regular intervals according to changes in temperature and humidity. When gravure printing is used to print aluminum foil products, if the ink concentration is too low, the color of the printed text and pattern will not be bright, and a paste phenomenon will occur at the texture; if the ink concentration is too high, cracks will occur at the pattern, which not only wastes ink, but also It is easy to cause the printing surface to be uneven and not beautiful. In addition, the best ink should be selected according to the speed of the pharmaceutical aluminum foil printing and coating machine and the depth of the ink hole of the printing gravure roller.
3. Pharmaceutical aluminum foil adhesive should meet the requirements
The adhesive of PTP pharmaceutical aluminum foil is coated on the inner side of the aluminum foil. Its function is to make the aluminum foil and the pharmaceutical PVC hard sheet can be firmly heat-pressed, so that the medicine in the plastic hard sheet blister is separated from the outside world, so as to make the medicine sealing purpose. In the process of loading the medicine for heat sealing, the adhesive layer is activated by heat and pressure, so as to be firmly bonded with the PVC plastic sheet, which requires that the adhesive layer and the PVC resin should have good heat sensitivity and compatibility with the substrate. compatibility.
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