Keywords: pharmaceutical packaging, PTP, aluminum foil, gravure printing, pharmaceuticals, tablets, capsules, packaging using blister packs are becoming more and more common. Pharmaceutical blister packs, also known as PTP (Press Through Packaging), use gravure printing technology to print text patterns on the surface of aluminum foil, and apply a protective layer, coating the adhesive layer on the other side of the aluminum foil. The brief process flow is: aluminum foil unwinding → gravure printing → drying → coating protective layer → drying → coating adhesive layer → drying → aluminum foil winding.
In the “Aluminum Foil for Pharmaceutical Packaging†national standard, there are clear requirements for the surface quality of printed aluminum foil for pharmaceutical use, and there are physical and chemical indicators for the performance of the protective layer and adhesive layer, so as to protect the medicinal PTP aluminum foil with good barrier properties. Sex, hygiene safety, heat sealability and good physical and mechanical properties. To achieve the above-mentioned requirements in the PTP aluminum foil printing and coating production process, it is still necessary to be familiar with the applied raw material properties, and attention should be paid to the following issues during the operation.
1. Grasp the characteristics of aluminum foil and printing ink The raw material used to produce PTP aluminum foil is industrial pure aluminum foil. The general requirement is 0.02mm in thickness, 98MPa in tensile strength, and 90kPa in breaking strength. The surface is clean, smooth, no wrinkle, no pressure Trace damage, no fluorescent material, surface wetting tension 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 may be degraded or deteriorated due to infiltration of oxygen, water vapor, and light, so the requirement for the pinhole degree is very strict. In addition, if the aluminum foil thickness exceeds the required deviation (10%), it will affect the coating amount of the adhesive layer and the protective layer, and should cause the operator's attention.
The printing inks used in aluminum foils are mainly divided into two categories: one is polyamide-based inks, which are mostly used for the printing of plastic films, and the heat-resistance performance meets the requirements for aluminum foil printing. The other category is based on vinyl chloride vinyl acetate copolymer resin / acrylic resin as the main component of the aluminum foil ink, its characteristics are bright color, high concentration, and aluminum foil adhesion is particularly strong, with good transparency. However, the volatility of the solvent is large. When printing on the surface of the PTP aluminum foil, the ink is likely to cause the ink knots and deposits in the ink hole of the gravure roll, resulting in a paste plate phenomenon. Therefore, it is necessary to carry out the necessary pretreatment for the deposition and freezing of the ink. The method is to stir or freeze the deposited and frozen ink. If the ink storage time is too long, the ink will appear to be deposited, resulting in more ink on the top of the resin solution, the bottom of the paint more, the upper color is light, the bottom color is dark, it should be used after stirring.
2. The amount of solvent added to the ink should be properly diluted with a thinner ink. When stirring with thinner, add the diluent evenly throughout the ink. Determine the viscosity between 20 and 30p using a viscometer. An ink concentration detector was used to determine the amount of solvent added, and the concentration of the ink was determined at regular intervals based on changes in temperature and humidity. When gravure printing is used to print aluminum foil products, the ink concentration is too low, which will cause the printed text pattern color to be not bright, and the graphics and text will produce stencil printing; if the ink concentration is too high, cracks will occur at the graphic and textual sites, which will not only waste ink. And it is easy to cause the surface of the brush to be uneven and not beautiful. In addition, the optimum ink concentration should be determined based on the speed of the aluminum foil coater and the ink hole depth of the gravure roll.
3. The adhesive should meet the requirements PTP aluminum foil adhesive is coated on the inside of the aluminum foil, its role is to make aluminum foil and medical PVC hard film can be firmly hot pressed together, so that the plastic hard film blisters inside the drug and the outside world Separated to achieve the purpose of sealing the medicine. In the process of loading the medicines for heat sealing, the adhesive layer is activated by heat and is firmly bonded to the PVC plastic hard sheet. This requires that the adhesive layer and the PVC resin should have good thermal sensitivity and compatibility with the substrate.
4. Printing and coating process should have a good grasp of the drying temperature and time printing graphics and adhesive layer and protective layer in the coating process need to be dried, the aluminum foil surface coating drying requires a process, it needs to be in the equipment drying The middle of the road stays for a certain period of time, depending on the speed of the winding of the coating machine and the temperature level selected in the drying tunnel. The two should maintain a corresponding relationship. Due to the different thickness of aluminum foil material, physical and mechanical properties are all different, and the thermal expansion, contraction, and elongation of the material when running in the equipment are also somewhat different, so it should not stay too long at very high temperatures, otherwise aluminum foil It is also prone to wrinkling and surface discoloration. Generally drying temperature control in 170 °C ~ 210 °C is appropriate.
5. Analysis of printing and coating speed, coating tension, and coating thickness and bonding quality The coating thickness of the adhesive layer during the printing and coating process has a great influence on the bonding strength of the plastic PVC hard sheet. The adhesive layer coating If it is too thin, the adhesive fastness of the PVC hard sheet may be reduced due to lack of material; if the adhesive layer is coated too thick, not only the cost is increased, but also the drying time needs to be lengthened, so it needs to be controlled within an appropriate thickness range. The coating thickness of the adhesive layer is affected by the binder concentration, coating tension, coating speed, and the number of anilox roller lines. In the case of coating roll pattern shape, depth, number of lines, and contact line pressure setting between the two rolls, the greater the adhesive concentration, the smaller the coating tension, and the faster the coating speed, the more the coating becomes. thick. Therefore, the thickness of the adhesive layer is generally adjusted by the concentration of the adhesive and the tension of the coater. Different types of aluminum foil have different requirements for the thickness of the adhesive layer. Generally, the thickness of the coating should be controlled at 3.5 to 7.0 μm. In the printing and coating of aluminum foil, the speed, temperature, and tension of the aluminum foil are related to each other and pinned each other. The quality of the aluminum foil is directly related to the quality of printing and coating of the aluminum foil.
The machine speed of the printing machine, the temperature of the drying tunnel, and the tension of the equipment during the printing and coating of the aluminum foil cause the cause of the product quality problem to be analyzed in the following table.
In the “Aluminum Foil for Pharmaceutical Packaging†national standard, there are clear requirements for the surface quality of printed aluminum foil for pharmaceutical use, and there are physical and chemical indicators for the performance of the protective layer and adhesive layer, so as to protect the medicinal PTP aluminum foil with good barrier properties. Sex, hygiene safety, heat sealability and good physical and mechanical properties. To achieve the above-mentioned requirements in the PTP aluminum foil printing and coating production process, it is still necessary to be familiar with the applied raw material properties, and attention should be paid to the following issues during the operation.
1. Grasp the characteristics of aluminum foil and printing ink The raw material used to produce PTP aluminum foil is industrial pure aluminum foil. The general requirement is 0.02mm in thickness, 98MPa in tensile strength, and 90kPa in breaking strength. The surface is clean, smooth, no wrinkle, no pressure Trace damage, no fluorescent material, surface wetting tension 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 may be degraded or deteriorated due to infiltration of oxygen, water vapor, and light, so the requirement for the pinhole degree is very strict. In addition, if the aluminum foil thickness exceeds the required deviation (10%), it will affect the coating amount of the adhesive layer and the protective layer, and should cause the operator's attention.
The printing inks used in aluminum foils are mainly divided into two categories: one is polyamide-based inks, which are mostly used for the printing of plastic films, and the heat-resistance performance meets the requirements for aluminum foil printing. The other category is based on vinyl chloride vinyl acetate copolymer resin / acrylic resin as the main component of the aluminum foil ink, its characteristics are bright color, high concentration, and aluminum foil adhesion is particularly strong, with good transparency. However, the volatility of the solvent is large. When printing on the surface of the PTP aluminum foil, the ink is likely to cause the ink knots and deposits in the ink hole of the gravure roll, resulting in a paste plate phenomenon. Therefore, it is necessary to carry out the necessary pretreatment for the deposition and freezing of the ink. The method is to stir or freeze the deposited and frozen ink. If the ink storage time is too long, the ink will appear to be deposited, resulting in more ink on the top of the resin solution, the bottom of the paint more, the upper color is light, the bottom color is dark, it should be used after stirring.
2. The amount of solvent added to the ink should be properly diluted with a thinner ink. When stirring with thinner, add the diluent evenly throughout the ink. Determine the viscosity between 20 and 30p using a viscometer. An ink concentration detector was used to determine the amount of solvent added, and the concentration of the ink was determined at regular intervals based on changes in temperature and humidity. When gravure printing is used to print aluminum foil products, the ink concentration is too low, which will cause the printed text pattern color to be not bright, and the graphics and text will produce stencil printing; if the ink concentration is too high, cracks will occur at the graphic and textual sites, which will not only waste ink. And it is easy to cause the surface of the brush to be uneven and not beautiful. In addition, the optimum ink concentration should be determined based on the speed of the aluminum foil coater and the ink hole depth of the gravure roll.
3. The adhesive should meet the requirements PTP aluminum foil adhesive is coated on the inside of the aluminum foil, its role is to make aluminum foil and medical PVC hard film can be firmly hot pressed together, so that the plastic hard film blisters inside the drug and the outside world Separated to achieve the purpose of sealing the medicine. In the process of loading the medicines for heat sealing, the adhesive layer is activated by heat and is firmly bonded to the PVC plastic hard sheet. This requires that the adhesive layer and the PVC resin should have good thermal sensitivity and compatibility with the substrate.
4. Printing and coating process should have a good grasp of the drying temperature and time printing graphics and adhesive layer and protective layer in the coating process need to be dried, the aluminum foil surface coating drying requires a process, it needs to be in the equipment drying The middle of the road stays for a certain period of time, depending on the speed of the winding of the coating machine and the temperature level selected in the drying tunnel. The two should maintain a corresponding relationship. Due to the different thickness of aluminum foil material, physical and mechanical properties are all different, and the thermal expansion, contraction, and elongation of the material when running in the equipment are also somewhat different, so it should not stay too long at very high temperatures, otherwise aluminum foil It is also prone to wrinkling and surface discoloration. Generally drying temperature control in 170 °C ~ 210 °C is appropriate.
5. Analysis of printing and coating speed, coating tension, and coating thickness and bonding quality The coating thickness of the adhesive layer during the printing and coating process has a great influence on the bonding strength of the plastic PVC hard sheet. The adhesive layer coating If it is too thin, the adhesive fastness of the PVC hard sheet may be reduced due to lack of material; if the adhesive layer is coated too thick, not only the cost is increased, but also the drying time needs to be lengthened, so it needs to be controlled within an appropriate thickness range. The coating thickness of the adhesive layer is affected by the binder concentration, coating tension, coating speed, and the number of anilox roller lines. In the case of coating roll pattern shape, depth, number of lines, and contact line pressure setting between the two rolls, the greater the adhesive concentration, the smaller the coating tension, and the faster the coating speed, the more the coating becomes. thick. Therefore, the thickness of the adhesive layer is generally adjusted by the concentration of the adhesive and the tension of the coater. Different types of aluminum foil have different requirements for the thickness of the adhesive layer. Generally, the thickness of the coating should be controlled at 3.5 to 7.0 μm. In the printing and coating of aluminum foil, the speed, temperature, and tension of the aluminum foil are related to each other and pinned each other. The quality of the aluminum foil is directly related to the quality of printing and coating of the aluminum foil.
The machine speed of the printing machine, the temperature of the drying tunnel, and the tension of the equipment during the printing and coating of the aluminum foil cause the cause of the product quality problem to be analyzed in the following table.
Printing coating quality problems Quality analysis 1 Printing and coating Cohesive layer thickness uneven, inconsistent depth Speed ​​and tension control changes inconsistent 2 Printing, adhesive layer, protective layer appears dry in the surface dry speed is too slow, drying temperature Low 3 material thermal deformation is too large, discoloration, crumpling machine speed is too fast, low drying temperature 4 left and right deviation when wrap, wrinkle, tear tension is too large, speed is slow
(Bai Bing Shandong Pharmaceutical Packaging Research Institute)
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