Converting Case Study


Sticking around L


abel and package converters and their customers, as well as the many others that have a say or are involved in product output, have to consider many factors before making a careful measured and final commercial and process commitment. Decision-making is a joined-up affair during which time economic, environmental, feasibility and marketing related objectives, such as brand/product image and presentation and what is expected of the label or packaging are discussed. Material properties and process fundamentals, including durability, conformability, flexibility, chosen method of printing and, if relevant, die cutting or the addition of tamper evident/anti- counterfeiting devices, must be allowed for. But it doesn’t stop there. The need for clarity, gloss, chemical resistance and moisture resistance may influence substrate and consumable (inks, adhesive) selection. Overriding everything – perhaps, other than cost, of course – is what do we want of the label or the package? If it is a label for a shampoo container, will it be taken in and out of the shower? If so, is the surface that the label is to adhere too flat or curved? Is the product container going to be squeezable? If the answer is in the affirmative, the label


MAKING CHOICES


Let’s consider the cosmetic or personal label. Cosmetic labels must stick fast to the container, irrespective of whether it comes into contact with water, plasticisers, alcohol or even the greasy or oily substances contained within the container. Much of a label’s effectiveness is due to its adhesive. After all, a visually imaginatively created heat resistant label for a scented candle will be judged to be a complete failure if the label fails to stay firmly in place and where it is supposed to be.


If our cosmetic or personal care product is going to be used in or near an area subject to high humidity such as the shower or bathroom then the label might need an adhesive with high shear resistance so that there is less risk of tearing or cracking when the bottle or container is squeezed. For soft squeeze containers that have that textured look and which


By RK Print managing director, TomKerchiss


and, most importantly, its adhesive is going to be subjected to a great deal of flexing and deformation. There is a lot to think about when it comes to designing and producing a label or a package; and that includes choosing the adhesive.


feel velvety to the touch or have been embossed or de-bossed an aggressive and permanent adhesive might be judged necessary to obtain optimum adhesion. The production of products, such as pressure-sensitive adhesives for labels and for tapes, is primarily a coating and laminating process. The objective sounds simple: deposit a uniform amount of adhesive onto a web. It is, however, subject to many variables. Adhesives are available in a variety of adhesive formulations, each subject to specific viscosities and levels of solids. Different applications require various thicknesses and coating weights. The coating of adhesives for pressure sensitives is usually accomplished either by direct or transfer coating. In the case of the former the adhesive is coated directly onto the face stock or a backing material. With the transfer method the adhesive coating is first coated onto a release coated liner and transferred to the face/backing to liner lamination. PS-adhesive items may be coated via the pre-metered method, that is the thickness of the adhesive is pre-determined prior to applying it to a web. Post metering is another option. In post-metering the adhesive or amount of the adhesive is determined after that adhesive has been deposited on the web. The actual choice of coating method and coating applicator depends upon the viscosity of the adhesive, its solids content, the characteristics of the substrate being coated and the coat weight parameters, etc. Pre-metered methods of coating include reverse roll coating and gravure. The latter can provide for a smooth coating profile and, as such, may be regarded as being very good for coating pressure sensitive adhesives on clear film stocks. Gravure and reverse roll coating are amongst the coating technologies that can be supplied with RK Print Coat Instruments VCML- Lab/pilot coater.


Post-metering methods of coating include meter bar. This method of coating is often used to coat solution or emulsion-based


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July/August 2021


convertermag.com


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