Pressure sensitive adhesive labels (PSAL) have added to the appeal, shelf life and brand value of pharmaceutical products. Sachin Jagdale analyses various aspects related to PSAL and their impact on the pharma industry
Mechanics of PSAL
The pressure-sensitive product consists of a face material, a pressure-sensitive adhesive and a liner. The liner is coated with a silicon layer, which protects the adhesive layer and releases the face material and adhesive at the point of application. Pressure is needed on the label during application to make the adhesive stick to the surface.
PSALs are used for several varied applications. The name itself suggests that through the application of little pressure by hand the label can be applied or removed with equal ease. These labels are aggressively and permanently tacky / sticky at room temperature and generally adhere/ stick to a variety of surfaces with just finger or hand pressure. They require no activation with water, solvents or heat. PSALs provide an easy way to apply the flexible backing. They also provide a convenient and fast means of application that would be difficult for the other methods to meet.
Shrikant Athavale Proprietor, Prathith Consultants |
Shrikant Athavale, Proprietor, Prathith Consultants, says, “The adhesive will have sufficient strength so that the coated layer does not break up. The adhesive bonding and de-bonding involves certain amount of energy. The PSAL forms a film having good elasticity and have to possess properties like, tack, peel and shear.”
Athavale explains these properties, “Tack (the property which makes the product to stick quick) is the ability of PSAL to form a bond in a short time, with little pressure. Hence, the adhesive needs to have good flow. Peel (the property responsible for resistance to remove or peel off from the applied surface ) is the force required to peel off the PSAL from the applied surface. Shear (the property which decides the holding power of the product) is nothing but the resistance to shear stress.”
Importance of PSAL for pharma
PSALs provide many advantages to the pharma industry: their visual appeal, shelf life increases brand value and sales of the product.
Anil Sharma Mng. Director – Materials (South Asia), Avery Dennison |
“PSAL is a very clean, reliable and fast method of labelling compared to other technologies (e.g. wet glue labelling is slower and the glue could be a source of contamination. Shrink sleeve labelling involves increased temperature that could affect the medicine). PSAL allows functionality in the label with regards to security solutions (e.g. tamper evidence, sequential numbering and other anti-counterfeit functions like holograms or taggants). Self-adhesive labels can be designed to meet specific requirements of the pharma industry, such as migration, sterilisation, low temperature applications, freeze conditions, etc,” informs Anil Sharma, Managing Director, Materials, South Asia, Avery Dennison.
CK Narayanan, Packaging Consultant – Industrial Design, TATA ELXSI, says, “PSAL allows greater packaging design flexibility with fewer limits on label size and shape, for improved shelf appeal.” He adds, “Other benefits of PSAL are application versatility and functionality like front back labelling, wrap around labelling, contoured label applications etc, better end-use performance, capital and operational efficiencies, and better overall total applied cost. The label which is a key part of the packaging can make the difference between success and failure of a product. The appearance of the package is essential for great shelf impact, so is the quality of the label. The PSAL delivers this aspect. These account for the major preference by the pharma industry.”
According to Athavale, the most important and critical requirements of PSAL for pharma industry are, autoclavable, sterilisable, antistatic, sterilisation indication, change in colour indication, and most importantly no residue of adhesive on the packets.
Scope for improvement
The total construction of a PSAL consists of a variety of layers, each layer having a specific function and purpose. The PSAL consists of a release liner, an adhesive and a face stock. “In some cases, a top coat may be applied to the face stock to enhance ink adhesion. When required, a protective over-laminate or UV coating may also be applied,” informs Narayanan.
C K Narayanan Packaging Consultant – Industrial Design, TATA ELXSI |
He adds, “While the pharma industry may use predominantly paper based PSAL, the cosmetics or the personal products industry tend to use both paper based as well polyolefin based PSAL. The ‘no look’ label plays a key role in the cosmetics industry with respect to enhancing the shelf appeal and impact and not offering the appearance of an applied label. Contoured or profiled ‘die cut’ labels also play a key role in enhancing the shelf appeal and impact.”
The composition, structure, the adhesive varies, keeping in mind the end use or application. The label/tape composition depends on the type of application. According to Athavale, label/tape can be meant for packing, for reinforcement, for insulation (this could be heat insulation, or electrical insulation), for mounting, for decoration, or any other application in particular. Based on such end applications, the backing material (for example paper, film, metal foil, elastic foam, woven or non woven fabric), has to be selected.
“Depending on the application and end-use conditions each component can vary. For example, shampoo bottles used in the shower will have plastic labels because paper labels will absorb water and become unreadable. Products that are used out door or in applications that need a long lifetime have to meet more stringent requirements than labels on fast moving consumer goods (FMCG),” says Sharma. He adds, “Labels used in the pharma industry must meet the sterilisation requirements or, in case of plastic bottles, must not have components that can migrate through the bottle wall into the (liquid) medicine.”
Options to PSAL
PSAL is one of the most effective ways of labelling for the pharma industry and other industries as well. However, does this kind of labelling have any equally strong and reliable alternative? According to industry experts, scope for improvement is always there.
“There are many ways of labelling, but PSAL is the most convenient, reliable, cheaper way. They are capable of fulfilling almost all the requirements, related to strength, printability, weather resistance, temperature resistance, water resistance and so on,” opines Athavale.
While highlighting one of the very significant limitations of PSAL, Narayanan says, “PSAL will not be suitable if full body 3600 wrap around labels with graphics are a requirement. Then, shrink sleeve labels will be the best alternate label option.”
Sharma says, “It is difficult to identify a labelling technology that has all the advantages that can be incorporated in one technology like in pressure-sensitive. One could think of using shrink sleeve labelling for tamper evidence, but production and processing is slower and investment costs are relatively higher.”
|
Elements of PSAL |
More to explore
Though PSALs have done a job much to the satisfaction of its users, on the innovation front, industry experts still want modifications/improvements to be done.
“There is a big potential to manufacture labels/ tapes, where all the ingredients/ components, such as the backing, the adhesive, the ink are biodegradable, or repulpable, recyclable. These could be based on paper, with suitable waterborne adhesive, that is repulpable. The cost is a concern here, since there is no repulpable adhesive manufacturer, based in India and one has to depend on imports,” opines Athavale.
According to Sharma, there will be more functionality built in labels, like with RFID, sensoric properties and ability to be applied on difficult substrates.