There are many structural forms of packaging machines, including single-blister substrate structure and double-blister substrate-less structure. The packaging material is mainly composed of a thermoplastic film for blister and a backing substrate.
The substrate is also the main component of the blister packaging machine. Like plastic film, the size, shape, and quality (weight) of the packaged material must be considered when selecting it. Substrates mainly include white cardboard, coated composite materials (mainly coated with heat seal coating), corrugated cardboard, coated aluminum foil and polyvinyl chloride composite materials.
1. Plastic film
There are many types and specifications of plastic sheets used in blister packaging machines. The size, quality, value and impact resistance of the packaged product must be considered when selecting, and whether the packaged product has sharp or prominent edges and corners, and the material itself Heat-sealability and ease of cutting, etc., while also considering the adaptability of the plastic film and the packaged material, that is, the selection of materials to meet the technical requirements of blister packaging, and minimize packaging costs.
The rigid plastic sheets used in the blister packaging machine include cellulose, polystyrene, polyethylene resin, polyvinyl chloride, composite aluminum foil, etc. Among them, cellulose is the most commonly used, such as cellulose acetate, cellulose butyrate, acrylic Acid cellulose, etc., they all have excellent transparency and thermoformability, good heat sealing and grease resistance, but the heat sealing temperature of cellulose is generally higher than other plastic sheets. Directionally stretched polystyrene has excellent transparency and good heat-sealability, but it has poor impact resistance and is easily broken, even worse at low temperatures. The price of vinyl resin is generally cheaper than that of polystyrene. There are hard and soft ones, and they have better transparency. It has good heat-sealability with layered cardboard, and it can improve cold resistance and impact strength after adding plasticizer. For the contents that require barrier properties and protection from light, plastic sheets and aluminum foil composite materials should be used; non-toxic plastics such as non-toxic polyvinyl chloride (PVC) should be used for packaging food and medicine, and they must meet hygienic standards.
2. Substrate
The substrate is also the main component of the blister pack. Like plastic film, the size, shape, and quality (weight) of the packaged material must be considered when selecting it. The substrate is often white cardboard. White cardboard is made of bleached sulphate wood pulp, or recycled cardboard is used as the base layer and covered with white paper. The size, shape and quality of the contents should be considered when selecting. The surface of the substrate should be white and shiny, with good printability, and be able to apply the heat-seal coating firmly to ensure that after the heat-seal coating melts, the substrate and the blister can be tightly combined to prevent the contents from falling off Out. The substrate material can also choose B-type or E-type coated corrugated paper, coated aluminum foil and various composite materials.
3. Coating materials
In addition to plastic films and substrates, the choice of coating materials is also crucial. If the coating material is not selected properly, it may cause damage to the blister film during heat sealing. Therefore, the heat-seal coating should be compatible with the substrate and the blister; it is required that the heat-sealing temperature should be relatively low, so that it can be quickly heat-sealed without causing damage to the blister film. Commonly used heat-sealable coating materials include solvent-resistant vinyl resin and water-resistant acrylic resin, both of which have good gloss, transparency and heat-sealability.
