Application Analysis of Aluminum Foil Gravure Printing Materials

Pharmaceutical blister packaging is also known as "blister eye" packaging. It is one of the main flexible packaging forms for solid dosage forms such as pharmaceutical tablets, capsules, and pills. Because of its many advantages, this form of packaging is highly valued by pharmaceutical companies and welcomed by drug users. Blister packs are those in which a drug is placed in a cavity (referred to as a blister or blister) in a hard plastic molded plastic sheet, followed by an aluminum foil that is printed and coated with a protective agent and an adhesive. Hard plastic sheets are glued and sealed so that medicines are protected. Pharmaceutical blister packaging materials include materials coated with protective and adhesive layers, known as protective agents and adhesives, pharmaceutical aluminum foil substrates, ink materials capable of printing text and patterns on aluminum foil, and plastic hard disks. China's use of more plastic hardening material is PVC (polyvinyl chloride). Pharmaceutical blister packs were raised in Europe in the 1930s. China's blister packaging materials used in the early 1970s mainly depended on imports. In the 1980s, China's Guangzhou, Lianyungang, Jinzhou and other places have introduced Japanese pharmaceuticals. Aluminum foil gravure coating equipment and its application technology, but the main materials such as substrate aluminum foil need to be imported. In the 1990s, China has been able to manufacture single-color or multi-color aluminum foil printing and coating equipment, and can print golden series of pharmaceutical packaging aluminum-plastic products, while the blister packaging used in pharmaceutical aluminum foil materials, aluminum foil printing ink , Aluminum foil protective agents, adhesives have been made, and can meet domestic demand.

1 Application Status of Aluminum Foil Printing Materials

Printing materials Aluminum foil is a sealing material that is sealed on medical plastic hard sheets and is also called a cover material. Its surface can print text or patterns, and both sides have good printing performance. The aluminum foil material is made of 99% electrolytic aluminum, made by post-deceleration and other processing methods. It is non-toxic and odorless. It has high-quality conductivity and light-shielding properties as well as extremely high moisture resistance and gas barrier properties. Because aluminum foil has a highly dense metal crystal structure, it can completely block any gas. In modern packaging, almost all shade-requiring or high-barrier composite flexible packaging materials use aluminum foil as a barrier material. The aluminum foil used in pharmaceutical blister packaging printing is made of industrial pure aluminum foil as a substrate, printed on a medicinal aluminum foil printing and coating machine, and coated on one surface with an adhesive. The aluminum foil used has a thickness of 0.02 mm. Its adaptability and quality indicators for printing mainly include: the number of pinholes of aluminum foil, the heat-sealing strength of the adhesive layer, the adhesiveness of the protective layer, the heat resistance, the rupture strength, the content of volatiles, easy oxides and heavy metals, and abnormalities. toxicity. These indicators can ensure that the aluminum foil has good barrier properties, hygienic properties, heat sealability and good mechanical strength after printing. At present, the application status of aluminum foil in China, from the quality compared with imported products, there is still a gap, mainly in the following aspects:

1. The number of pinholes in medicinal aluminum foil does not meet the requirements for use. The number of pinholes in aluminum foil is a penetrating defect, which seriously affects the barrier property of aluminum foil. Especially when applied to the outer packaging of medicines, it is easy for oxygen, water vapor and light to penetrate and reduce the efficacy of the medicine. Pharmaceutical aluminum foil national standards require that aluminum foil can not have pinholes with a diameter greater than 0.3 mm, and pinholes with a diameter of 0.1 mm to 0.3 mm cannot have more than one pinhole per square meter. Currently, domestic aluminum foil rarely meets this standard.

2. The thickness of domestically-made medicinal aluminum foil is not uniform, and its tensile strength is low. Different thickness will affect the uniformity of the amount of adhesive used to coat, and thus affect the heat sealing strength of aluminum foil and plastic hard sheet. The low tensile strength will cause the foil to break when tension is applied during the printing process, thus preventing continuous printing operations.

3, aluminum foil surface residual oil. Because aluminum foils are cooled and shaped by oil during the calendering and stretching process, there are often oil stains in the finished aluminum foil. This type of surface oil contamination can affect the adhesion of aluminum foil printing inks and protective agents to aluminum foil materials, resulting in a series of quality problems, such as unclear writing, peeling of protective agent and aluminum foil, and the like. In particular, when gold foil is printed on the surface of a foil or a color pattern is printed, due to the presence of grease on the surface of the foil, the word and the pattern and the aluminum foil have almost no adhesive force, resulting in discoloration and falling, and seriously affecting the quality of the product. At present, the dosage of medicinal aluminum foil is increasing year by year. It is expected that the dosage will exceed 5,000 tons in 2002. In addition to the solid-type packaging for Chinese and western medicines such as tablets, capsules, and pills, there are also packages for health products, and they are widely used in injection kits. package.

2 Foil Gravure Ink Variety

At present, there are many types of printing inks on the market with different brands. However, considering the special requirements for the printing process of pharmaceutical aluminum foils and pharmaceutical packaging, the inks for aluminum foils must meet the following requirements: Good adhesion to aluminum foils, printed texts The pattern is clear and firm, with quick solvent release, good heat resistance, excellent rubbing resistance, good gloss, non-toxic pigments, and chemical components in the ink will not migrate the packaged drug. The viscosity meets the requirements of the aluminum foil printing process. Combining these factors, the inks currently suitable for aluminum foil printing fall into two major categories: The first type is inks of alcohol-soluble polyamides. Because polyamide resin has good adhesion to various substrates, it is especially suitable for printing polyolefin plastic film, with good dispersion, high gloss, softness, good abrasion resistance, solvent release and printing performance. Good, so it is mostly used for surface printing of LDPE, CPP, OPP film. These inks are resistant to blocking, drying, and heat resistance to meet the requirements of aluminum foil printing and are therefore also used in aluminum foil printing. However, since such inks are not special inks for aluminum foil printing, peeling may occur during large-area printing of aluminum foils. At present, domestic manufacturers have produced special polyamide inks for gravure printing of aluminum foil. In the 200°C high temperature heat sealing experiment, printed characters and patterns are still clear without discoloration. The second category is based on vinyl chloride, vinyl acetate copolymer resin and acrylic resin as the main ingredient of aluminum foil ink. This gravure ink is characterized by its bright color, high concentration, particularly strong adhesion to aluminum foil, good transparency, and excellent reproducibility of aluminum foil, but due to the gravure ink, its solvent volatility Large, used for printing on the surface of aluminum foil is likely to cause the gravure roll ink in the ink hole dry knot, resulting in stencil phenomenon, while the surface of the ink tank easy surface crust, resulting in aluminum foil surface color, color lines and other quality problems, need further improvement.

3 Aluminum Foil Printing Protective Agent Adhesive Application

The industrial production of medicinal aluminum foil is to apply ink protection agent on the characters or patterns printed on the surface of aluminum foil. Apply adhesive to the other side of the aluminum foil. The purpose of applying the protective agent on the surface of the aluminum foil is to prevent the abrasion of the printing ink layer on the surface of the aluminum foil, and also to prevent the outer layer of the ink from contacting the inner layer of the adhesive layer during the mechanical operation of the winding process to cause the contamination of the medicine during packaging. The role of the adhesive layer is to allow the aluminum foil and the plastic rigid sheet to heat and bond together so that the medicine can be sealed. Most of the protective agents used today are solvent-based, and their main chemical components are roughly: Nitrile fiber synthetic resins, plasticizers, true solvents, cosolvents, and thinners. These ingredients are mixed at a certain ratio, and are stirred with a reactor to form a solvent, which is coated on the aluminum foil by a printing machine to produce a protective film. The specific requirements for the protective agent are that aluminum foil has good film adhesion and flexibility, good transparency gloss, good heat resistance, no residual odor, protection of the printing ink layer does not fall off, and high wear resistance. Currently used adhesives are mainly single-component sols or two-component sols. The main component of one-component sol is natural rubber or synthetic rubber, and it can also be made of nitrocellulose, acrylic acid and solvent. As the main agent is a macromolecule elastomer and a tackifier is used as an auxiliary agent, an organic solvent can be used to stir and react the mixture in an autoclave to form an emulsion. This emulsion has non-dryness and hot-melting properties. It has a certain adhesive strength after aluminum foil coating, and it is heat-sealed with PVC after dry coating. The heat sealability is good. This adhesive has been widely used. In production. However, with the improvement of the hygienic and sealing performance requirements of packaging materials for pharmaceuticals, the trend of using two-component adhesives has become increasingly evident. The two-component adhesive is a urethane adhesive mainly composed of a main agent and an ammonia curing agent. The main agent generally contains many active hydrogens such as hydroxy oxime, ammonia hydrazine, etc. The curing agent is composed of polyisocyanate compounds. When the isocyanate quinone in the curing agent is in contact with the active hydrogen in the main agent molecule, an addition reaction is automatically performed to generate the structure of the amino phthalate ester so that the molecular weight will be doubled when the main agent and the curing agent are combined with each other. Even cross-linked products having a steric conformation with a branched structure are generated. It has good high and low temperature resistance, high resistance to media erosion and high adhesion. Because polyurethane molecules contain a large number of polar oxime groups, a large dipole moment, and a great affinity for the adherent material, they work for various packaging materials such as aluminum foil and plastics. In addition, the isocyanate in the curing agent is a very reactive reaction oxime, which not only reacts with the active hydrogen in the main agent molecule, but also reacts with the active hydrogen in the surface material of the adherent material to form a chemical bond. This bridges the adhesive molecules with the bonded material, resulting in stronger adhesion. Due to the high bonding strength of such adhesives, it is widely used in composite flexible packaging of aluminum-plastic composite packaging and various types of plastic film. In the future, the application of adhesives for aluminum foil coating will gradually develop toward the direction of solvent-free. Its composition is also a two-component type of polyurethane adhesive, with the difference that the viscosity of the main agent and curing agent at room temperature is high, but still It is a semi-solid substance with rolling property. When used, the main agent and curing agent are mixed in proportion and placed in a container with heating and heat preservation function. After the temperature is raised, the viscosity is reduced. Then, the gravure roll with insulation function is applied to the printed aluminum foil base. On the material, no drying is required to directly dry the paste after the glue is applied, because the glue itself has no solvent and can be directly bonded to another coffin, so there is no problem of exhaust emissions, which is beneficial to environmental protection, and because it does not It is necessary to equip the printing and coating equipment with huge drying ovens and blower exhaust devices, which can also save equipment investment costs.

4 Application Status of Material Blister Hard Film Heat Sealed with Aluminum Foil

At present, China's most widely used blister plastic hard piece is PVC (polyvinyl chloride) material, the general thickness of 0.25mm. PVC hard sheets have good processability, heat sealability, transparency and barrier properties as well as mechanical strength. Since the drug is sensitive to moisture and light transmission, it is also required to have good barrier properties against water vapor, light and odors for plastic hard sheets. However, the performance of PVC hard sheets in blocking water vapor transmission is not ideal, so it is not suitable for the packaging of drugs with high moisture-proof requirements. In the future, polyvinylidene dichloride (PVDC) composites will have more room for development as pharmaceutical packaging materials. Due to its high polymer density, ideal structure, and high crystallinity, PVDC has extremely strong gas tightness, excellent moisture resistance, and good resistance to oil, chemicals, and solvents. In particular, it has excellent barrier properties to oxygen, water vapor, and carbon dioxide gas in the air. The barrier properties of PVDC with the same thickness are 1500 times that of PE (polyethylene), 100 times that of PP (polypropylene), and 100 times that of PET (polyester). Water vapor resistance is also superior to PVC. In addition, PVDC not only has excellent barrier properties against gas and odor, but also the impact strength, tensile strength, and durability performance of the seal can meet the special requirements for pharmaceutical packaging. It is the future direction of development, and PVDC composite materials will also be large application. At present, domestic PVDC composite materials mainly include PVC/PVDC/PE composites, PVC/PVDC composites, and PVDC/OPP/PE composites. The barrier properties of these composite materials are greatly improved compared with PVC, and they have broad market prospects in the field of pharmaceutical packaging.

5 Inspection of printed aluminum foil and its materials

After printing, the aluminum foil was handed to the pharmaceutical factory together with the PVC hard film. The pharmaceutical company used a fully automatic packaging machine to heat the aluminum foil and the PVC blister filled with the tablets together. At present, the automatic packaging machine used in the pharmaceutical industry in China has various forms such as “vertical”, “horizontal”, “intermittent”, and “continuous” in its production form; the internal structures of different types of equipment are similar. It is composed of PVC hard sheet molding part, drug supply part, PVC and aluminum foil connection part, and cutting part. In order to ensure the quality of products, the printed aluminum foil and blisters pharmaceutical companies can be tested in accordance with the requirements of ZBC 08003 Pharmaceutical Aluminum Blister Packaging. Mainly detects the sealing quality of aluminum foil and blisters,