IV. History and Future of Adhesives for Blister Soft Packaging Materials
Blister packaging adhesives, early adhesives used single-component pressure-sensitive adhesives, the main components of pressure-sensitive adhesives include synthetic resin adhesives (including natural rubber, synthetic rubber, cellulose, polyacrylates ), Adhesives (including rosin, rosin esters, various petroleum resins, epoxy resins or phenolic resins, etc.), plasticizers (including chlorinated paraffins, phthalates), antioxidants, stabilizers, cross-linking Agents, colorants and fillers. In the early days, pressure sensitive adhesives were based on natural rubber. The formula was 100 parts of plasticized natural rubber, polyterpene resin had a melting point of about 75Â°C, and petroleum resin contained 5 parts and partially polymerized. Methyl dichloroquinoline 2 parts mixed.
Another formula consists of 100 parts of smoked rubber tablets, 50 parts of zinc oxide, 75 parts of hydrogenated rosin, and a small amount of tackifier and plasticizer. Later, synthetic rubbers and synthetic resins were used instead of natural rubber. Among them, acrylates and their copolymers are most commonly used. For example, acrylic copolymer emulsions are used to make high-strength pressure-sensitive adhesives. The mixing ratio and manufacturing method is 100 parts. Amount of butyl acrylate - 2-ethylhexyl acrylate - vinyl acetate copolymer emulsion (composition ratio of 50:17:33) and 30 parts of 50% solids ethylene-vinyl acetate-vinyl chloride copolymer emulsion (composition The ratio was 19:36:45.) Mixing, coating on a polypropylene film treated with corona discharge, drying at 110Â°C for 1 minute, was made into a pressure-sensitive adhesive tape. This tape has a peel strength of stainless steel of 600g/25mm. With the continuous improvement of the hygienic performance requirements of pharmaceutical packaging materials, the additives added to natural rubber adhesives have odor, and some are toxic. They are not used in pharmaceutical and food composite packaging, but acrylic pressure-sensitive adhesives Still have certain advantages, such as because it is a single component, will not be cross-linked curing, do not have to glue, simple to use, unused glue even if overnight or longer will not degenerate, as long as sealed airtight preservation However, the surface state of the adherend is excellent, and many non-polar materials such as plastics and metal materials can adhere to a small surface tension. However, due to the wide variety of materials in the packaging of compound drugs, companies have turned to two-component polyurethane adhesives for the compounding of polar plastics and non-polar materials.
At present, pressure-sensitive adhesives for pharmaceutical flexible packaging composite materials have been replaced by polyurethane adhesives, and ester-soluble polyurethane adhesives are mainly used. These adhesives are two-component ester-soluble adhesives, and their main agents are polyether or polyester polyols modified with aromatic isocyanates. Hydroxyl-containing polyurethane polyols, curing agents are a combination of aromatic isocyanates and trimethylolpropane. Such adhesives have excellent performance, mature technology, and many varieties, but they are toxic and costly, and they emit large amounts of solvents to pollute the environment. Long time of composite materials may cause hydrolysis and release of a carcinogenic substance, which will seriously affect the operator's health. As the awareness of environmental protection increases, the use of such adhesives continues to decline. The use of alcohol-soluble polyurethane adhesives; it is based on industrial alcohol as a solvent, low production costs, good health performance, harmless to humans, no pollution to the environment. The disadvantage is that it is not resistant to high temperatures of 100Â°C and cannot be packaged with highly corrosive products. Another type of adhesive is an aqueous polyurethane adhesive based on water-soluble or water-dispersible solvents. Its advantage is that water replaces organic solvents. There is no danger of burning and the cost is low. However, poor adhesive properties.
At present, the adhesives for composite flexible packaging materials develop toward solvent-free type, and solvent-free adhesives are basically two-component polyurethane adhesives. The main agent and curing agent have high viscosity at room temperature and fluidity, and the main agent and curing agent are compounded. Proportional mixing, after the temperature rises, the roller is applied to the substrate. Since no organic solvent is used, the cost is reduced. There is no environmental pollution caused by the volatilization of the organic solvent, which saves the huge drying, heating, air blowing, and exhaust emission devices of the device and reduces the Energy consumption. The product has no residual solvent damage, the production speed is increased, the maintenance cost is low, and the benefits are significant. In the field of pharmaceutical flexible packaging, it is the future development direction.
Fifth, anti-counterfeit labels for pharmaceutical blister packaging and new materials and new technology applications look forward to strengthening
At present, the blister package PTP aluminum foil surface printing is very simple, monochrome printing is more common, almost no security signs and special counterfeit materials and means, which provides counterfeiters with the convenience of prevention and fraud. According to information, there are nearly 10 types of anti-counterfeit signs on a slap-sized pillbox in Western countries. It uses micro-letters, anti-counterfeit signs that can be visually recognized, such as lacquering and gravure printing on banknotes. A fake-like logo that can be seen using special lenses. In addition, on the surface of pharmaceutical blister packaging, foreign countries mostly use laser holographic dark anti-counterfeit PTP aluminum foil products, the advantage of which is that the laser hologram pattern has strong intuitiveness and is easy for consumers to identify without affecting the original printing design and product packaging appearance. , does not affect the performance of using PTP aluminum foil material. This anti-counterfeiting product is a counterfeit method adopted by many multinational pharmaceutical companies. The application of invisible fluorescent anti-counterfeiting PTP aluminum foil material is also one of the development trends of pharmaceutical packaging technology in the future. This anti-counterfeiting effect is more subtle and difficult to observe with the naked eye, but the anti-counterfeiting mark or pattern text under the UV lamp will be clearly exposed. At present, some blister packaging manufacturers in China have already been applied, but the total amount used is still very small. Overall, China's pharmaceutical packaging companies are still relatively backward in terms of anti-counterfeit technology. Although we have seen alarming cases of counterfeit drugs in the pharmaceutical market, awareness of the importance of anti-counterfeiting technology and the importance of use has gradually increased, but in the new security materials and anti-counterfeiting technology The investment application is unsatisfactory, and it is necessary to focus on strengthening the promotion and use of counterfeiting in this area for a long time to come. For example, one or more anti-counterfeiting technologies can be used for pharmaceutical packaging: digital security, ink security, special printing anti-counterfeiting, nuclear track anti-counterfeiting, biological security, and DNA anti-counterfeiting technology are the future development direction of pharmaceutical packaging anti-counterfeiting applications.
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