Aluminum foil printing for the hottest drug packag

2022-08-16
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Aluminum foil printing for drug packaging

at present, blister packaging is becoming more and more popular for drug tablets and capsules. Blister packaging of drugs, also known as PTP (press through packaging), is a linkage process in which industrial pure aluminum foil is used as the base material, and on the pharmaceutical PTP aluminum foil coating machine, the gravure printing technology and roller coating method are used to print text patterns on the surface of aluminum foil, and the protective layer is coated, and the adhesive layer is coated on the other side of aluminum foil. The brief process flow is: aluminum foil unwinding? gravure? dry? Coating? dry? Apply adhesive layer? dry? Aluminum foil winding. In the whole production process, the surface quality of gravure printed text patterns, the heat sealing strength of the bonding layer, the adhesion and drying temperature of the protective layer, as well as the speed and tension control of the coating machine need to be strictly controlled in the process operation. Therefore, in the national standard "aluminum foil for pharmaceutical packaging", there are clear requirements for the surface quality of printed words of pharmaceutical aluminum foil, as well as physical and chemical indicators for the performance of protective layer and bonding layer, so as to protect pharmaceutical PTP aluminum foil with good barrier, health and safety, heat sealing and good physical and mechanical properties. In order to meet the above requirements in the production process of PTP aluminum foil printing and coating, it is necessary to be familiar with the properties of the applied raw materials, and pay attention to the following problems in the operation process:

1. Master the characteristics of aluminum foil and printing ink

the raw material used in the production of PTP aluminum foil is pure aluminum foil for industrial use, which generally requires a thickness of 0.02mm, a tensile strength of 98 kPa, a rupture strength of 90kpa, a clean, flat surface, and no wrinkles, No indentation damage, no flakes of fluorescent substances, and the surface wetting tension is not less than 32. The requirement for the pinhole of medicinal aluminum foil is that the pinhole with a diameter of 0.1 ~ 0.3mm is not more than 1/m2. Because the pinhole in aluminum foil is a penetrating defect, the medicine will be reduced or deteriorated by the invasion of oxygen, water vapor and light, so the requirements for pinhole are very strict; In addition, if the thickness of aluminum foil exceeds the required deviation (10%), it will affect the coating amount of bonding layer and protective layer, which needs the attention of the operator

at present, the printing inks used for aluminum foil are mainly divided into two categories: one is polyamide inks. This kind of ink has good adhesion, dispersion, gloss, wear resistance, solvent release and softness for the printing of various substances. It is mostly used for the printing of plastic films. When used in the printing of aluminum foil materials, the excellent performance of this kind of ink can be shown, and its heat resistance can also meet the requirements of aluminum foil printing. The other is the special ink for aluminum foil, which is mainly composed of vinyl chloride vinyl acetate copolymer synthetic resin/acrylic acid resin. Its holding point is bright color, high concentration, especially strong adhesion with aluminum foil, and good transparency. However, due to its high solvent volatility when used in gravure printing, when used in pharmaceutical PTP aluminum foil surface printing, it is based on the technical feasibility The advantage of cost and the possibility of production are easy to cause ink drying and deposition in the ink hole of gravure roll, resulting in the phenomenon of paste. Therefore, it is necessary to carry out necessary pretreatment for the deposition and freezing of the ink. 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 deposit, resulting in more resin solution in the upper layer, more pigments in the lower layer, light color in the upper layer and deep color in the lower layer. It should also be mixed evenly before use

2. The amount of solvent added to the ink should be appropriate

when the ink with high hiding degree needs to be diluted with a large amount of diluent, it should be stirred while adding diluent to make the diluent evenly distributed in the whole ink. The measuring time of the instrument is about 20 ~ 30s. Indoor temperature and humidity have an impact on the ink concentration. It is best to use the ink concentration detector to determine the amount of solvent added, and measure the ink concentration at regular intervals according to the changes of temperature and humidity. When using intaglio printing to print aluminum foil products, the ink concentration is too low, which will cause the color of the printed text pattern to be not bright, and the paste phenomenon will occur at the lines; If the ink concentration is too high, cracks will occur at the image, which not only wastes ink, but also easily causes uneven and unsightly printing surface. In addition, according to the speed of the aluminum foil printing coater and the inking hole depth of the gravure roller, the best ink should be formulated

3. The adhesive should meet the requirements to form two series of all electric injection machines and three series of electro-hydraulic servo injection machines. The adhesive of PTP aluminum foil is coated on the inner side of the aluminum foil. Its function is to make the aluminum foil and medicinal PVC hard sheet can be firmly geothermal pressed, so that China, the number one auto producing country, can separate the drugs in the plastic hard sheet Blister from the outside world, so as to achieve the purpose of sealing the drugs. In the process of loading drugs for heat sealing, the adhesive layer is activated by hot pressing, so it is firmly bonded with PVC plastic hard pieces, which requires that the adhesive layer and PVC resin should have good heat sensitivity and compatibility with the substrate,

4. In the process of printing and coating, the drying temperature and time should be mastered

the printed graphics and text, as well as the adhesive layer and protective layer should be dried during the coating process, The drying of the surface coating of aluminum foil needs a process, so it needs to stay in the drying channel of the equipment for a certain time, which depends on the winding speed of the coating machine and the temperature selected in the drying channel. The two should maintain a corresponding relationship. Due to the different thickness of aluminum foil materials, there are differences in physical and mechanical properties, and there are certain differences in the thermal expansion, contraction and elongation of materials when they are running in the equipment, so they should not stay at a very high temperature for too long, otherwise the aluminum foil is also prone to wrinkling and surface discoloration. Generally, the temperature of drying channel should be controlled at 170 ~ 210 ℃

5. Analysis of printing and coating speed, coating tension, coating thickness and bonding quality

the coating thickness of the bonding layer in the printing and coating process has a great impact on the bonding firmness of plastic PVC hard films. If the bonding layer is coated too thin, the bonding firmness will be reduced due to lack of material when hot pressing PVC hard films; If the bonding layer is coated too thick, it will not only increase the cost, but also prolong the dry operation time, so it needs to be controlled within the appropriate thickness range. The coating thickness of the bonding layer is affected by the concentration of the adhesive, the coating tension, the coating speed, and the number of roller lines. When the shape, depth, number of lines per inch and the pressure of the contact line between the two rollers are set, the thicker the coating is, the greater the adhesive concentration, the smaller the coating tension and the faster the coating speed. Therefore, the thickness of the bonding layer is generally adjusted by the concentration of the adhesive and the tension of the coater. Different kinds of aluminum foil have different requirements for the thickness of the bonding layer. Generally, the coating thickness should be controlled within 3.5 ~ 7.0um. In the printing and coating of aluminum foil, the machine speed, temperature and tension are not only related to each other, but also contain each other. The cooperation between them is directly related to the printing and coating quality of aluminum foil

the change of the machine speed of the printing machine, the temperature in the drying channel and the tension of the equipment during the printing and coating of aluminum foil, resulting in the analysis of the causes of product quality problems are shown in the following table:

the analysis of the quality causes of printing and coating quality problems

the thickness and depth of the printing and coating adhesive layer are uneven, and the change of the machine speed and tension control are inconsistent

the printing, adhesive layer and protective layer are dry on the surface and dry inside, and the machine speed is too fast, The drying temperature is low

the thermal deformation of the material is too large, the discoloration and wrinkle machine speed are too slow, and the drying temperature is high

the left and right deviation occurs during winding, resulting in excessive wrinkle and tear tension, and the machine speed is too slow

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