Blister packaging is a packaging method that seals the product between a blister formed with a transparent plastic sheet and a bottom plate (made of cardboard, plastic film or sheet, aluminum foil or their composite material). Since this packaging method uses a substrate as a base, it is also called substrate packaging.
Packages made of blister packs have a transparent appearance on the one hand, so you can clearly see the appearance of the product; at the same time, beautiful patterns and product instructions can be printed on the substrate for easy display and use. On the other hand, the packaged product is fixed between the formed blister and the substrate, which is not easy to be damaged during transportation and sales. It can not only protect the product, extend the storage period, but also promote the goods and expand the sales.
Blister packs were primarily used for pharmaceutical packaging. In addition to the packaging of pharmaceutical products such as pharmaceutical tablets, capsules and suppositories, blister packaging is also widely used in the packaging of food, cosmetics, stationery, toys, gifts, tools and mechanical and electrical parts.
1 Blister packaging structure
There are many blister packaging structures, some are blister directly heat-sealed to the substrate, some substrates are inserted into special grooves, some substrates can be closed with dumpling chains, and some are all plastic without substrates. The common blister packaging structure is shown in Figure 1. Where (a) is the blister directly sealed on the substrate; (b) is the substrate inserted into the groove of the blister; (c) is the press-through blister; (d) is the blister sealed in die cutting On the substrate; (e) for the blister to be inserted into the groove of the substrate; (f) for the substrate with hinged openings; (g) for the substrate with folded parts, which can stand the product upright or hang on the shelf; (h) The contents can be extruded from the blister without opening the blister; (i) is a double-sided blister with die-cut holes in the substrate; (j) is all plastic without substrate separation Strip packaging; (k) double-layer substrate; (l) multi-blister separate packaging; (m) all-plastic hinged or double blister without substrate packaging; (n) chute type The blister pack of the contents can be taken out.
There are many ways to connect the substrate to the blister. In addition to heat sealing, other methods can be used to seal it. As shown in Figure 1, (a) shows heating above the plastic sheet, the heat passes through the sheet to seal it with the substrate, or it can be heated from below through the substrate to seal it with the blister; (b) is to seal the substrate Insert into the groove of the blister; (e) is to insert the blister into the groove of the substrate, this bonding method can be glued or nailed; (i), (k) is heated from the upper and lower directions, so that The substrate is sealed with the plastic sheet sandwiched therebetween. The sealing method can be selected according to the specific situation, without restricting one cell.
2 Blister packaging materials
The materials used for blister packaging are mainly plastic sheets, substrate materials, heat seal coating materials, etc.
1) Plastic sheet
The plastic sheet used in the blister pack must have sufficient barrier properties against oxygen, carbon dioxide and water vapor, as well as high transparency and mechanical strength that is not easy to crack. The rigid plastic sheets used for blister packaging include cellulose, polystyrene, vinyl resin, polyvinyl chloride, and polyvinylidene chloride.
Cellulose is the most common application, there are cellulose acetate, cellulose butyrate, cellulose propionate, etc. They all have excellent transparency and thermoformability, good heat sealability and grease resistance, but cellulose The heat sealing temperature is usually 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, especially at low temperatures.
The price of vinyl resin is generally cheaper than polystyrene, there are hard and soft, with better transparency, it has good heat sealability with coated paperboard, adding plasticizer can improve cold resistance and Impact strength.
The rigid PVC sheet has good transparency and gloss. Polyvinyl chloride sheets used for pharmaceutical packaging have high hygienic requirements for resins, and non-toxic polyvinyl chloride resins, non-toxic modifiers and non-toxic heat stabilizers must be used. Since the medicine is very sensitive to moisture, moisture and light transmission, it is required to have good barrier properties of moisture, light and odor against plastic sheets. However, the barrier properties of currently used polyvinyl chloride are not ideal, and polyvinylidene chloride will replace it.
Polyvinylidene chloride has extremely strong gas tightness, excellent moisture resistance, good oil resistance, chemical resistance and solvent resistance, especially for oxygen, water vapor and carbon dioxide gas in the air. Polyvinylidene chloride not only has good gas and odor barrier properties, but also the sealing performance, impact strength, tensile strength and durability of the materials can meet the special requirements of pharmaceutical packaging. [next]
2) Substrate material
The substrate is usually white cardboard. The white paperboard is made of bleached sulfate wood pulp, or made of recycled paperboard covered with white paper. The size, shape and quality of the contents should be considered when selecting. The thickness of the white cardboard substrate ranges from 0.35 to 0.75 mm, and the thickness of the commonly used cardboard is 0.45 to 0.60 mm.
The substrate material can also be coated aluminum foil, B-type or E-type coated corrugated paper and various composite materials. For example, aluminum foil has a highly dense metal crystal structure, has good barrier properties and light-shielding properties, so it can protect the packaged objects most effectively, and is widely used in pharmaceutical blister packaging. Aluminum foil is made of electrolytic aluminum with a purity of 99%, which is made by rolling. It is non-toxic and odorless, has excellent electrical conductivity and shading, and has extremely high moisture resistance, gas barrier and taste retention. Aluminum foil also has good printability, and can print text patterns on both sides. The thickness of the aluminum foil material for printing is usually between 0.021 and 0.027 mm, and is composed of an aluminum foil layer, a printing ink layer, a protective layer, and an adhesive layer.
The surface of the substrate should be white and shiny, with good printability, and can be firmly coated with a heat seal coating to ensure that after the heat seal coating is melted, the substrate and the blister can be tightly combined to prevent the contents from falling out Out.
3) Coating material
The heat-sealing coating should be compatible with the substrate and the blister, and the heat-sealing temperature should be relatively low so that the heat-sealing can be performed quickly without damaging the blister film. Commonly used heat-seal coating materials are soluble vinyl resin and water-resistant acrylic resin, which have good gloss, transparency and heat-sealability.
3 Blister packaging process
1) Blister packaging process
The blister cavities in blister packs vary in size, and the shape varies according to the shape of the packaged item; those with or without substrates are useful. And there are many types of blister packaging machines. Nevertheless, the basic principle of blister packaging is roughly the same, and its typical process is:
Sheet heating → film forming → filling product → laying substrate → heat sealing → trimming.
The blister packaging process has three methods: manual operation, semi-automatic operation and automatic operation.
â‘ Manually operate the plastic sheet blister pre-formed, the substrate is pre-printed and cut; during packaging, manually load the product into the blister, cover the substrate, and then use a heat sealer to seal the blister and substrate . Some products do not have high requirements on the temperature and humidity of the circulation environment, and can be sealed with a stapler without heat sealing.
â‘¡Semi-automatic operation will send the reel or single plastic sheet into the semi-automatic blister packaging machine. The machine operation is continuous or intermittent; the number of forming molds depends on the size of the product and the production volume. Column type; after the sheet is formed and cooled, the product is manually loaded into the blister; the printed substrate in the form of a roll or a single sheet is covered on the blister, and then heat sealed and trimmed to obtain a complete package Pieces.
â‘¢Automated operation In the automated operation, in addition to the above packaging processes, printing, installation instructions, cartoning and other processes can also be connected to the production line. This automatic packaging production line is suitable for mass production of a single variety. Its advantages are high productivity, low cost, and compliance with hygienic requirements. [next]
4 Blister packaging equipment
Blister packaging machine is a machine that forms a transparent plastic film or sheet into a blister, and seals the product between the blister and the bottom plate by means of heat sealing and bonding.
The blister packaging machine is divided in terms of overall structure and working principle, including a roller blister packaging machine, a roller plate blister packaging machine, and a flat plate blister packaging machine. Especially the roller plate blister packaging equipment combines the two advantages of plate forming and roller sealing, so it is widely used. It can pack various specifications of drug dragees, plain tablets, capsules, capsules and shaped tablets. It is used for packaging small foods such as chocolate beans and bubble gum. However, when large-diameter medicines, capsules, and shaped tablets with a diameter exceeding 16 mm are obliquely arranged on the plate at an angle exceeding 45 °, such packaging equipment is not suitable.
According to the degree of automation, there are three types of blister packaging machines: semi-automatic packaging machine, automatic packaging machine and automatic production line. Especially in the case of automated operation, in addition to the completion of the packaging process, the processes of printing, loading instructions, and cartoning can also be connected to the packaging line to form a fully automated blister packaging production line.
Although there are many types of blister packaging equipment, it is mainly composed of the following parts:
â‘ Heating part (that is, heating the plastic sheet to soften it to facilitate molding)
There are two heating methods: direct heating and indirect heating. Direct heating is to make the sheet contact with the heater, the heating speed is fast, but uneven, suitable for heating thin materials; indirect heating is to use radiant heat, heating near the sheet, the heating is thorough and uniform, but the speed is slow, suitable for thick and thin material.
â‘¡There are two methods for forming the blister, namely compression molding and suction molding. Compression molding is to use compressed air to blow the softened sheet against the mold to make it adhere to the four walls of the mold. The mold adopts a flat plate shape, which is generally intermittent transmission or continuous transmission. Its molding quality is good and it is suitable for deep and shallow blister. . Vacuum forming is to use vacuum to absorb the softened sheet on the four walls of the mold to form the cavity of the blister. Most of the mold adopts the shape of a roller that is continuously conveyed. The suction force generated by the vacuum is limited. The angle away from the drum is limited, so it is only suitable for shallower blister and thinner materials.
â‘¢ Filling device quantitatively fills the medicine into the formed blister, and quantitative automatic filling device is mostly used.
â‘£The heat sealing device seals the covering aluminum foil substrate material on the blister, there are two types of flat type and roller type. The flat type is used for intermittent transfer, and the drum type is used for continuous transfer.
5 Conclusion
Blister packaging is a hot-press forming packaging method with controllable dose. It takes out the packaged items by a simple squeeze method, which is very convenient for users. With the continuous updating of packaging materials and the continuous improvement of the performance of packaging equipment, China's blister packaging will develop in the direction of humanized design, multi-function and environmental protection. The market also needs this kind of packaging form that can directly see the internal products. It is expected that the blister packaging will be one of the flexible packaging forms that will be widely used and rapidly developed in the future.
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