In the eye of the consumer, the packaging of a product plays a fundamental role in the preservation of a brand’s image. One could argue that the label of a product acts as the corporate face of a brand, which means that poorly applied labelling (whether it is creased, inadequately aligned or displaying poor quality) will affect the consumer’s perception of the product and therefore the brand in question.
For companies that are looking to increase their consumer appeal and protect their products against contamination and counterfeiting, in-mould labelling (IML) provides the ideal labelling technology. A product decoration method that has experienced a surge in popularity throughout the past couple of decades, today we find numerous industries taking an active interest in this technology, including food, beverage, cosmetic, healthcare, pharmaceutical and even automotive.
The market for in-mould labels is projected to grow from USD 2.58 billion in 2015 to USD 3.23 Billion by 2020, at an estimated CAGR of 4.54% . This growth can be attributed to a number of factors, such as increasing technological advancements in the packaging sector, leading to cost-efficient manufacturing processes, as well as a surge in awareness among consumers about sustainable labelling and packaging. The unremitting growth of the food and beverage industries also provides an opportunity for further market expansion, especially in the emerging Asia Pacific and Latin American regions.
IML stands out thanks to its ability to provide better durability, reduce waste and costs, and deliver a noticeable improvement in the packaging’s quality. With the ability to insert superior quality printed labelling directly into a mould, whereby the label becomes a part of the packaging, the consumer is more likely to be won over by the ingenious design and therefore be more inspired to purchase the product in question.
How does IML work?
The term “in-mould labelling” derives from the manufacturing process in which a label is applied to a plastic packaging container. The label is placed within the mould as the container is being formed, instead of being applied to the surface of the finished product with an adhesive.
Traditional paper’s relative incompatibility for recycling with plastic has long constituted a major drawback for IML. For example, differences in shrinkage dynamics could lead to panel bulges or retention blisters, which would then affect the product’s overall presentation. As a consequence, the waste generated by such issues would cause further cost and handling problems, especially when it is necessary to remove the paper labels from the plastic containers to allow recycling.
Recycling has long been one of the primary incentives to invest in synthetic papers for IML applications, as plastic films (such as polypropylene, or polyethylene) share many of the chemical characteristics of the containers they decorate, which in turn allows them to be recycled along with the container.
Other advantages over traditional labelling include better moisture and product resistance, as well as superior tear and abrasion resistance, both of which extend the packaging’s shelf life. More importantly, the plastic films have shrinkages that are a better match for the container materials, therefore helping to significantly reduce the quality issues that arise with traditional labels.
Injection moulding or blow moulding?
IML can be achieved via a number of forming methods, the two most popular being injection moulding and blow moulding. Both methods are effective for labelling applications, but each has a different set of characteristics.Injection moulding involves inserting molten plastic material into a cavity, or mould, which then takes the form of a container, while the label is fitted inside the cavity prior to the plastic being injected. Once the plastic material has been injected into the mould, it is allowed to cool, with the label effectively becoming amalgamated with the container. Among the key benefits that this method offers is the possibility to label all of a polygon-shaped container’s sides at the same time, a procedure which is not possible with glue applied, heat transfer, or pressure-sensitive labelling.
The blow moulding process is not dissimilar to blowing up a party balloon. With the heated plastic material being extruded in the form of a tube, a mould is clamped around the pipe as a jet of air is blown out against the cavity walls to take the shape of the container. As with injection moulding, the label is applied against the cavity wall and adheres to the formed container, due to the heat activated glue on the labels surface, as it cools down and settles into its final shape. Thanks to this method of moulding, the container can be flexed and squeezed with no danger of the label peeling off the surface, therefore resulting in longer durability and also allowing the brand to reproduce higher quality graphics.
The role of static in pinning labels and the methods employed
The biggest challenge in IML has always been ensuring that the label is successfully pinned to the mould according to specifications. While most businesses endeavour to limit the presence of static in their production environments to avoid quality issues and improve health and safety, in-mould labelling companies actually rely on static generation for the delivery of their products.
In the early days of IML, the label would be placed within the mould tool and held into the required position by using a vacuum system. This proved to be a flawed method due to a number of mechanical issues, such as instances where a label was placed incorrectly into the tool and where molten plastic would block the vacuum channels. Furthermore, this process required a high level of maintenance and was more expensive than modern day systems.
As a result, static generation was considered a viable option for fitting labels to mould tools by pre-charging the labels and applying them within the cavity of the injection moulding machine. But in order for this method to be successful, certain types of inks, varnishes and materials needed to be used, so that the static charge could hold the label to the injection moulding tool surface. Pre-charged labels were also more susceptible to contamination, as the presence of static attracted dust and particles to their surface during the transfer between the charging point and placement within the injection moulding tool. Finally, production environments with high humidity levels caused labels to lose charge quicker, affecting conductivity and resulting in higher scrap rates on humid days.
The next step in perfecting the IML method was to transfer the electrical charge on to the label whilst inside the mould tool. There are a number of methods to achieve this, such as conductive foams and conductive resins. However, these two methods require close machining tolerances of the cavity and the mandrel, while also including high costs, a short production life of the mandrel and alignment issues between the mandrel and the mould tool.
The more viable alternative for inducing an electrical charge on the label’s surface is pinning heads. While earlier pinning technologies would use large heads, the high levels of electrical charge stored in the heads could result in sparking, which would in turn damage the face of the mould tool. As a result, a smaller, resistive electric pinning system was necessary and that is where Meech’s IML solution comes into play.
Meech’s solution – electric pinning heads and a compact generator
Meech International has been specialising in static control technology for decades and has called upon that experience to develop solutions for IML that meet the requirements of OEMs and end users.
One of the most common challenges encountered in the IML market is dealing with diminutive containers and labels. The solution to this problem is the creation of a miniaturised IML pinning system specifically designed for use in applications where small items are being moulded.
The Meech 994 Hydra is a system of this kind, providing powerful, repeatable pinning with no degradation over time. The components of the 994 Hydra system are easy to mount, as well as being straightforward to connect and disconnect during mould tool changes. The design eliminates the chance of sparking and the possibility of expensive damage to the mould tool. The choice of materials ensures that the problem of potential contamination of the container, sometimes seen with conductive foam based IML systems, is eliminated.
The standard 994 Hydra system consists of resistively coupled distributors connected in series to the new 994CG, a compact generator designed to meet the greater demands of the IML sector.
The 994CG is a miniature generator with four 4-25kV outlets, making it the most powerful of its kind on the market. With customer feedback indicating that 24V DC power is the preferred supply voltage for ancillary equipment on machinery, the IML generator reduces power consumption, removes the need to route high voltage cables next to signal wires and low voltage cables and has a small footprint, with dimensions of only 150 (L) x 38 (W) x 40 (H) mm, allowing easy installation.
Adding further to the 994CG’s versatility is the ability to connect four six-headed Hydra miniaturised IML pinning systems directly to the compact generator, allowing it to be configured for multiple cavity applications.
The global IML market looks set to thrive over the coming years, with a reduction in labelling costs being a major contributor to this projected growth. Aside from being 100% recyclable and eliminating the need for labelling processes on manufacturing lines, IML’s key strength is its ability to help maximise packaging appeal, prevent label tampering and guarantee superior adhesion. This means that, as long as there is a demand for high quality packaging, clear instruction labelling or the product requires a damage resistant finish, which will effectively convey a brand’s marketing message, there will be a role for in-mould labelling. And with static control being a key component of the IML process, there will also be a requirement for label pinning technologies that ensure that end product quality is always guaranteed.
More info: www.meech.com