Current situation and application of adhesives for

2022-08-19
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Current situation and application of adhesives for blister flexible packaging of drugs

blister packaging is formed by placing drugs in the pits (called blisters or blisters) of plastic hard films formed by suction molding, and then gluing and heat sealing a piece of aluminum foil printed by intaglio and coated with protective agent and adhesive with the plastic hard films, so that drugs can be safely protected. The main materials of blister packaging are pharmaceutical PTP aluminum foil, plastic hard pieces (PVC), and adhesives. With the further improvement of the safety requirements of blister packaging materials in China, this paper reviews the history and current situation of the materials used, and analyzes the future development direction, in order to promote the survival of the fittest of pharmaceutical packaging materials

I. brief history of the development of pharmaceutical blister flexible packaging in China

pharmaceutical blister packaging was formed in Europe in the 1930s. China initially introduced equipment, technology and raw materials in the 1980s. In the 1990s, China has been able to manufacture monochrome or multicolor PTP aluminum foil printing and coating equipment, which has been used by domestic pharmaceutical packaging enterprises, and can manufacture color series of pharmaceutical flexible packaging aluminum-plastic Blister products. At present, PTP aluminum foil gravure printing equipment in China has been able to meet the needs of domestic pharmaceutical packaging. China has obtained the production license of pharmaceutical packaging materials, and 165 blister material manufacturers, including film, film, aluminum foil (composite) flexible packaging enterprises, have a considerable production scale. Because blister packaging is widely used, it is the fastest-growing flexible packaging material in recent years, and it is also food, health care products The main packaging forms in drugs and other fields have promoted the expansion of reproduction in these fields, and the number of newly-built packaging enterprises is also increasing

II. Current situation of aluminum foil for flexible packaging

pharmaceutical PTP aluminum foil is a sealing material sealed on medical plastic hard pieces, which is usually called capping material. Its surface can be printed with words or patterns, and both sides have good printing applicability. Aluminum foil is made of 99% electrolytic aluminum by calendering and other treatment methods. It is non-toxic and tasteless, with excellent conductivity, shading, high moisture resistance, gas resistance and other excellent properties. In modern packaging, aluminum foil is used as barrier material in almost all composite flexible packaging materials requiring shading or high barrier. This is because aluminum foil has a highly dense metal crystal structure, which can completely block any gas. Most of the thickness used in the flexible packaging of drugs is double zero foil. The consumption of double zero aluminum foil in China reached 60000 tons in 2002, of which nearly 50000 tons were self-produced and nearly 20000 tons were imported. Therefore, from the perspective of the development prospect of the aluminum foil market for flexible packaging in China, the market has good growth, and there is a huge development space for both consumption and product grade

from the perspective of daily consumer goods, China can consume 161300 tons of aluminum foil every year. The product with the largest market consumption is air conditioning foil, followed by cigarette foil. China is the world's largest cigarette production and consumption industry platform, and is gradually improving. The annual consumption of cigarette foil in cigarette packaging is 35000 tons, accounting for 60% of the total consumption of double zero foil. Third, decorative foil, which is used for heat insulation, moisture-proof and decorative materials in the construction industry. At present, China's construction The appliance industry has formed an upsurge in the application of decorative foil. The fourth is cable foil, which uses the airtightness and shielding of aluminum foil as a shield for cables. Therefore, aluminum foil is widely used, and has become the second largest consumer of aluminum foil in the world after the United States. However, its per capita share is less than 1/10 of that of developed countries, especially the packaging consumption is far less than that of developed countries. It is one of the materials with broad development space in the future

III. current situation and development of plastic rigid sheet materials for blister flexible packaging

PVC rigid sheet (PVC rigid sheet for short) is the most common base material used in PTP aluminum-plastic blister packaging. Since the blister packaging production mode was adopted, PVC materials have been used to complete the blister packaging of drugs. Although PVC has many advantages such as high quality and low price, in the process of PVC production or use, there has been an impact on the environment and organisms for a long time. The main problems are; Polymerized PVC monomers such as vinyl chloride monomers. Additives for preparing PVC plastics, such as plasticizers, stabilizers, etc. Products from the incineration of PVC, such as dioxin hydrochloride. Because HCl produced after PVC decomposition has a certain impact on the environment, its monomer, plasticizer and stabilizer are harmful to human body

according to relevant reports, German drug manufacturers no longer use PVC as blister packaging, and Japan also restricts the production of PVC products, which needs our high attention. Therefore, the PVC sheet commonly used as blister packaging material for drugs will be gradually eliminated. Instead, the blister packaging plastic sheet requires that it is non-toxic and has good water and oxygen isolation performance, so as to ensure that the drug will not oxidize, absorb moisture, mildew, deteriorate, etc. within the validity period for a long time, especially for traditional Chinese medicine, it is more sensitive. However, due to the poor performance of PVC hard sheet in blocking water vapor transmission, it is not suitable for drug packaging with high moisture-proof requirements. In order to improve the defects of PVC, PVC composite hard sheet has been applied at present. This composite sheet is mainly produced by PVC hard sheet and another or several new polymer material films and sheets through extrusion, compounding, coating and other processing methods, which meets the requirements of drug packaging. In the 1990s, the safety of drugs has been paid more and more attention by pharmaceutical enterprises and consumers. Because the components of some drugs are prone to deliquescence and oxidation, the original PVC hard tablets can no longer meet the packaging requirements of these drugs

China has successfully developed composite materials based on PVC hard sheet and added some high barrier polymer materials, such as PVC and PVDC composite, PVC and PE composite, pvc/pe/pvdc composite, etc. It integrates the good rigidity, good molding and excellent barrier to water vapor, oxygen, carbon dioxide gas and various odors of PVC hard films, and can meet the packaging requirements of drugs that are easy to deliquescence and oxidize and some traditional Chinese medicine that need to retain odor. At the same time, these composite hard films still use the original aluminum-plastic blister packaging form, packaging equipment and technology

IV. history, current situation and future of adhesives for blister flexible packaging materials

adhesives for blister packaging in the early stage were single component pressure-sensitive adhesives. The main components of pressure-sensitive adhesives include synthetic resin adhesives (including natural rubber, synthetic rubber, cellulose, polyacrylate), adhesives (including rosin, rosin ester, various petroleum resins, epoxy resin or phenolic resin, etc.) Plasticizers (including chlorinated paraffins and benzoic acids), 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 2-ethylhexyl 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 on polypropylene film treated by corona discharge, and dry it at 110 ℃ for 1min to make pressure-sensitive tape. The peel strength of this tape to stainless steel is 600g/25mm. With the continuous improvement of the requirements for the hygienic performance of drug packaging materials, the additives added to the adhesive with natural rubber ratio have peculiar smell and some are toxic, which have not been used in the composite packaging of drugs and food. However, acrylic pressure-sensitive adhesive still has certain advantages. For example, because it is a single component, it will not be crosslinked and cured, so it does not need to be mixed with adhesive, and the unused adhesive will not deteriorate even if it is used overnight or for a longer time, As long as it is sealed and stored without air leakage, the surface of the adherend is in good condition. Many non-polar materials such as plastic and metal materials can stick firmly with low tension before the second restart. 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 Flexible Packaging Composites for drugs has been replaced by polyurethane adhesive, mainly ester soluble polyurethane adhesive, which is a two-component ester soluble adhesive. Its main agent is polyether or polyester polyol aromatic isocyanate modified polyurethane polyol containing hydroxyl, and the curing agent is the compound of aromatic isocyanate and trimethylolpropane. This kind of adhesive has excellent performance, mature technology and many varieties, but it is toxic and costly. 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 seriously affects the health of operators. With the enhancement of environmental awareness, 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 of composite flexible packaging materials is developing in the direction of solventless. Solventless 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 exhaust emission devices of the equipment are eliminated, 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

v. the application of anti-counterfeiting marks and new materials and new technologies for drug blister packaging is expected to be strengthened.

at present, the surface printing of PTP aluminum foil for blister packaging is very simple, monochrome printing is relatively common, and there are almost no anti-counterfeiting marks and special fake materials and means, which provides convenience for counterfeiters to prevent and fabricate. It is reported that in western countries, there are nearly 10 kinds of anti-counterfeiting marks on a palm sized medicine box. It uses anti-counterfeiting marks that can be recognized by the naked eye, such as microfilms, glazing and gravure printing technology on banknotes, as well as counterfeiting marks that can be seen by using special lenses. Table 43 shows the comparison of the properties of transparent conductive films. In addition, on the surface of drug blister packaging, most foreign countries use laser holographic dark grain anti-counterfeiting PTP aluminum foil products. Its advantages are that the laser holographic pattern is intuitive, easy for consumers to identify, and does not affect the original printing design and product packaging appearance, and does not affect the performance of PTP aluminum foil materials. This anti-counterfeiting product is a counterfeiting means adopted by many multinational pharmaceutical group companies at present. 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 kind of anti-counterfeiting effect is relatively hidden, with the naked eye

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