The hottest polyurethane adhesive will dominate th

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Polyurethane adhesive will dominate the field of flexible packaging of drugs.

blister packaging is the process of placing drugs in the pits (known as "blister" or "blister eye") of plastic hard pieces formed by suction molding, and then bonding and heat sealing a piece of aluminum foil printed by gravure and coated with protective agent and adhesive with the plastic hard pieces, so that drugs can be safely protected. The main materials of blister packaging with high cost performance are pharmaceutical FFP aluminum foil and plastic hard pieces (polyvinyl chloride, PVC) and adhesives in such periods of upheaval

the adhesive used for blister packaging used single component pressure-sensitive adhesive in the early stage. The main components of pressure-sensitive adhesives include synthetic resin adhesives (including natural rubber, synthetic rubber, cellulose and polyacrylate), adhesives (including rosin, rosin ester, various petroleum resins, epoxy resins or phenolic resins, etc.), plasticizers (including chlorinated paraffin and benzoic acid), antioxidants, stabilizers, crosslinkers, colorants and fillers. In the early days, pressure-sensitive adhesives were mainly composed of natural rubber. Their formula was 100 parts of plasticized natural rubber, 75 parts of polypinene resin with a melting point of about 70 ℃, 5 parts of petroleum resin and 2 parts of partially polymerized trimethyl dichloroquinoline

another formula is made up of 100 parts of plasticized cigarette rubber, 50 parts of zinc oxide, 75 parts of hydrogenated rosin and a small amount of tackifier and plasticizer. Later, synthetic rubber and synthetic resin were used to replace natural rubber, among which acrylate and its copolymers were most widely used, such as acrylic copolymerization lotion to make high-strength pressure-sensitive adhesive, The proportioning and manufacturing method is to mix 100 parts of butyl acrylate acrylic acid 2 ethyl hexyl acrylate vinyl acetate copolymer lotion (composition ratio: 50:17:33) with 43% solid content and 30 parts of ethylene vinyl acetate vinyl chloride copolymer lotion (composition ratio: 19:36:45) with 50% solid content, apply it to the polypropylene film treated by corona discharge, and dry it at 110 ℃ for 1 minute to make pressure-sensitive tape. This kind of tape peels off stainless steel. The strength is 600g/25mm. With the continuous improvement of the requirements for the hygienic performance of drug packaging materials, because the additives added to the adhesive with natural rubber ratio have peculiar smell and some are toxic, they are no longer used in the oil free outflow of the oil return pipe of drug and food composite packaging, but acrylic pressure-sensitive adhesive still has certain advantages. For example, because it is a single component, it will not be cross-linked and cured, so it is not necessary to prepare adhesive, and it is simple to use; The unused glue will not deteriorate even overnight or longer, as long as it is sealed and stored without air leakage; Moreover, the surface of the adherend is in good condition. Many non-polar materials, such as plastic and metal materials, can stick firmly with low surface tension. However, due to the wide variety of materials in the packaging of composite drugs, enterprises have turned to two-component polyurethane adhesives for the composite of polar plastics and non-polar materials

at present, the pressure-sensitive adhesive used in pharmaceutical flexible packaging composites has been replaced by polyurethane adhesive, mainly ester soluble polyurethane adhesive. This kind of adhesive is a two-component ester soluble adhesive. Its main agent is polyurethane polyol containing hydroxyl after polyether or polyester polyol aromatic isocyanate modification, and the curing agent is the synthesis of aromatic isocyanate and trimethylolpropane. This kind of adhesive has excellent performance, mature technology and many varieties, but it is toxic and costly, and a large number of solvents discharged by it pollute the environment. The composite material may be hydrolyzed for a long time, releasing a carcinogen, which will seriously affect the health of the operator. With the increasing awareness of environmental protection, the use of this adhesive continues to decline

application of alcohol soluble polyurethane adhesive: it uses industrial alcohol as solvent, with low production cost, good sanitary performance, harmless to people and no pollution to the environment. The disadvantage is that it is not resistant to 100 ℃ high temperature and cannot package highly corrosive products. Another kind of adhesive is water-based polyurethane adhesive based on water-soluble or water dispersible solvents. Its advantage is that water replaces organic solvents, there is no danger of combustion, and the cost is low. But the adhesion performance is poor

at present, the adhesive for composite flexible packaging materials is developing in the solvent-free direction. The solvent-free adhesive is basically composed of two-component polyurethane adhesive. Its main agent and curing agent have high viscosity and fluidity at room temperature. When compounding, the main agent and curing agent are mixed in proportion. After heating up, they are roller coated on the substrate. Because there is no organic solvent, the cost is reduced, and there is no environmental pollution caused by the volatilization of organic solvent, The huge drying, heating, air blowing and waste gas emission devices of the equipment are omitted, and the energy consumption is reduced. The product has no residual solvent damage, the production speed is improved, the maintenance cost is low, and the benefit is significant. It is the future development direction in the field of pharmaceutical flexible packaging

information source: Chemical Information Port

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