Abstract:Thermosetting acrylic resin and nitrocellulose are used to make aluminum foil protective coating for pharmaceutical packaging. The production process of resin, preparation and properties of lacquer are introduced, and various influencing factors are discussed.
Keywords: pharmaceutical packaging, aluminum foil, thermosetting acrylic resin, nitrocellulose, protective coating
Aluminum foil blister packaging for pharmaceuticals is the most widely used pharmaceutical packaging method. It has the advantages of moisture-proof, safety and hygiene, long shelf-life, easy to carry and use, etc. Meanwhile, it also has the advantages of low cost, fast production speed and convenient transportation. Aluminum foil for pharmaceutical packaging generally consists of 5 parts: protective layer, outer printing, aluminum foil substrate, inner printing, adhesive layer. The role of the protective layer is mainly:
(1) Modify the surface of aluminum foil, so that the surface of the aluminum foil is bright, smooth, embedded in the surface of the aluminum foil of small gaps.
(2) Improve the resistance of aluminum foil to acid and alkali erosion, prolonging the shelf life of drugs.
(3) It has a certain hardness and adhesive strength, protects the printing ink on the outside, and adheres well to the aluminum foil substrate without falling off. In high temperature compounding (150-180 ℃) not because of the softening of the viscous and make the coating stick to the stick of the drug packaging machine. This test uses thermosetting acrylic resin, through the appropriate nitrocellulose, additives, solvents, etc., to get good heat resistance, strong adhesion, full coating, rapid drying, good uncoiling, excellent performance of the aluminum protective coating for pharmaceutical packaging.
1 test part
1.1 Raw materials and instrumentation
1.1.1 Main raw materials and specifications
Methyl methacrylate, industrial grade; butyl acrylate, industrial grade; methacrylic acid, industrial grade; acrylamide, industrial grade; formaldehyde,
industrial grade; initiator, reagent; auxiliary, industrial grade; nitrocellulose,
industrial grade. Cellulose,
Industrial Grade; Solvent, Industrial Grade.
1.1.2 Test instrumentation
Super thermostatic water bath; electric heat jacket; electric stirrer; X-1 rotary vane vacuum pump; constant temperature drying oven; commonly used glass instruments.
1.2 Synthesis of thermosetting acrylic resin
1.2.1 Recipe
The thermosetting acrylic resin recipe is shown in Table 1.
1. 2. 2 Synthesis process
In a four-necked bottle equipped with a stirrer, reflux condenser, and thermometer, add the solvent methanol. Turn on the stirring and raise the temperature. At reflux temperature, according to a certain order of reaction monomer and initiator were added dropwise. After all the drops were finished, the reaction was carried out for 2 h. Then, toluene was added and the methanol was evaporated. After all the methanol is evaporated, the temperature is lowered to obtain thermosetting acrylic resin.
1.2.3 Technical specifications of thermosetting acrylic resin
The technical specifications of thermosetting acrylic resin are shown in Table 2.
1.3 Preparation and Performance of Aluminum Foil Protective Coating for Pharmaceutical Packaging
1.3.1 Lacquer Preparation
Add thermosetting acrylic resin, nitrocellulose, additives and solvent according to the formulated amount, and then stir well.
2 Results and Discussions
2.1 Selection of Raw Materials
Aluminum Foil Protective Coating for Pharmaceutical Packaging The important performance requirements are that the protective layer formed on the rigid aluminum foil has strong adhesion to the aluminum foil, and has high hardness without sticking off during high-temperature hot-press lamination (150-200℃:). Nitrocellulose has good tensile strength, high hardness, fast solvent release, and its content reaches a certain level to meet the hardness requirements. Thermosetting acrylic resin is used for metal surfaces as a protective or modification coating, which has excellent performance in all aspects after curing, with excellent light retention, color retention, corrosion resistance, heat resistance, adhesion and other properties. After considering the performance of the two resins, nitrocellulose and thermosetting acrylic resin were selected as the main film-forming materials for the protective coating of aluminum foil for pharmaceutical packaging to ensure that the protective layer has good hardness, adhesion, heat resistance and corrosion resistance.