Heat sealing lacquer for sealing the blister with the blister film
The plastic push-through blister has to be sealed with a cover made of aluminium for the effective protection of tablets. For this purpose, heat seal lacquer, or any suitable sealing agent is applied to the aluminium foil. The aluminium foil is applied after the tablets are put in the individual cavities of the blister mold. By applying the right pressure, heat and time the plastic material of the blister combines with the heat seal lacquer on the aluminium foil. The two are perfectly sealed to protect the tablets from any environmental influences. To ensure that the consumer identifies the drug; a primer is printed on the blister package often other markings or manufacturer’s logo.
Both hard and soft aluminium is used for the push-through packaging. In the past, only hard aluminium foil was used because it can break easily and release the medicine with minimal pressure. The soft aluminium foil is considered children resistant because the film has high stretching power and, therefore, requires more force to flip open. This effect can be intensified by the use of a laminate aluminium with PET or paper.
Cover material made of hard aluminium
The European pharmaceutical industry prefers the hard aluminium foil of approximately 25 micrometers thickness. If the drug is to be taken, it can simply be pushed through the hard aluminium to push through the opening. The outside seal that is visible to the consumer is normally printed. In some instances, the inside sealed with the heat seal lacquer could also have some writings. It is mandatory to have a double coating with a heat seal primer applied with heat seal lacquer. The role of the primer is to ensure the heat seal lacquer securely adheres to the aluminium foil and is in line with the foil. The primer is dyed in some instances for marketing purposes. In such cases, the primer is followed by a heat seal lacquer. The heat sealant protects the medicine from the color pigments of the primer if it is dyed. The color pigments are placed between the heat sealant lacquer and the aluminium foil. The heat seal lacquer, color pigments, and the prime have to be perfectly matched.
Cover material made of soft aluminium
The use of soft aluminium is similar to that of hard aluminium foil. It is used when there is a need to protect children from accessing the tablets. It is preferable because it is soft and requires a lot of pressure to force open. The flexibility and thickness of the aluminium foil make it harder for children to open.
Blister film made of a composite of aluminium with paper / PET
Composite films of aluminium and paper and PET are used as cover films in the pharmaceutical industry. A paper of weight 40-50 g/m² is laminated with aluminium foil. Cover foils with paper and foil can be directly printed on the outward-facing surface of the paper. While the aluminium with paper is used as children protection in Europe, in the USA it is used as a peel-off foil, which is to be pulled down from the blister pack in one piece. This is referred to as peel-off-push-through packaging where first, composite of PET and paper must be removed before the tablet is forced out. For the paper to be peeled off as a whole, the aluminium foil has to be thicker.
Trends in pharma-industry
The pharmaceutical is fast growing with many people being able to afford medicine. With technology growth, companies are different and want diversified products. This has pushed technicians to become creative with the products, at the same time observing high standards.