Let's Be Clear!

By Tom Kerchiss, RK Print Coat Instruments

Going clear is one of many options that the packaging technologists and brand owner can consider. Obviously when it comes to the packaging of some foods it’s definitely not appropriate. For instance, snack foods such as crisps are best packed in flexible opaque filmic + metalized and combo pillow pouches and other flexible configurations. Crisps have a tendency to look greasy and unappealing when presented and viewed in a see-through pack. Crisps and many other foods sell better and are more appropriately packed in a filmic bag or in a carton. Sometimes how a product looks is best left to the consumer’s imagination or better still left to how the printer and converter reproduces a graphic image of how the item looks in more favourable circumstances.

However, many products do benefit from having a transparent or near transparent look. PETE or Polyethylene Terephthalate provides for a high degree of transparency and is widely used for the bottling of mineral water and fizzy drinks. A noteworthy benefit for many beverage applications is that PETE is ideal for carbonated beverages, preventing the egress of CO2 for a lengthy period of time after manufacture, distribution and sale.

Clear packaging or at least window filmic materials are suitable for showcasing some products where this form of differentiation is an advantage, enabling the consumer to feast with their eyes before they buy. Prepared gourmet ready to eat prime cuts of meats, cheeses, pizzas, rib eye steak and smoked salmon may be packed with a combination of film, paperboard and a clear window material.

An advantage of providing a pack with a clear window means that the brand owner and designer is not forced to compromise on other design elements such as colour, graphics, text and logo. The envelope window itself serves not only as an additional value-added feature, the plastic filmic technology and laminates now available or becoming more widely available can be engineered to manage gas, moisture and humidity transmission rates.

Packaging plays an important role in many product sectors, many of which have different processing, end-use requirements and display priorities, for example, the medical device and diagnostic product market. In industries where package performance integrity is top of the agenda, looks and glamour are less important. The purpose of the pack may be to maintain a sterile atmosphere for the product; protect an item against light, gases (ingress and egress), etc.
Many factors influence material selection, hence the need for vigorous product development programs, trialling and monitoring.  Systems such as the VCML Lab/Pilot Coater and the VCM or Versatile Converting Machine designed and developed by RK Print Coat Instruments Ltd speed the process of bringing products to market; enabling users operating across many sectors to trial materials, formulae and determine product feasibility and resolve issues that could, in the medium to long term impact on profitability and commercial success.

The VCML Lab/Pilot Coater enables operatives to print, coat and laminate on all types of flexible substrates and on a reel-to-reel basis. It can accommodate paper, films, metallic foil, etc. Configurable and adaptable it has the ability to apply various coatings including, inks, varnishes, adhesives and even paint using solvent and water based materials, etc. It also offers short run production capability making it ideal for production purposes, monitoring of quality and for undertaking real world trials, tests and procedures.

The VCML has a web width of up to 300 mm, a cantilevered unwind and rewind, head mounting station with tray lift and trough and a laminator station with pneumatic nip. In addition to offering offset gravure, flexo, gravure, knife over roll and other processing options, the VCML can be configured for UV curing, infrared, hot air drying and corona treatment. Edge guide and heated laminator and ATEX coating zone can also be provided for.

The Versatile Converting Machine or VCM coater is suitable for pilot or for production purposes and for many different industries. Designed, configured and optimised to meet the specific requirements of the customer and product sector the VCM can be considered to be very much a machine of its time, a 21st century machine that can be used for medical diagnostics, security, latent imaging, medical and advanced packaging product and material development and for solar reflective film, polymeric semiconductors, and much else beside.

With regard to the subject of medical and diagnostic sectors, medical and diagnostic clear packaging makes less use of envelope windows and greater use of transparent pouches and bags that enable a health care worker to quickly identify product contents, which can be important in an emergency. That is not to say that transparent items are devoid of printed matter. Printed information on flexible items must be clear and precise. Colour, which helps to clarify and identify products must be accurate and also plays a role in identification, when products are quickly taken from a medical despatch centre.

Colour communication or proofing devices such as the FlexiProof family of devices for users and producers of flexographic inks ensures colour matching accuracy, determines printability and can be used to trial materials, etc, in the pre-press area, the laboratory and in the printing and converting environment.  

The K Printing Proofer is an alternative option to the FlexiProof when high quality proofs are needed when using gravure or offset gravure processes. The K Printing Proofer also allows for proofing using flexo inks and as an added bonus wet or dry laminated samples can be produced.
Packaging technologists and associates, chemists, film manufacturers and converters have an array of materials to choose from including, multi-web structures, laminates and composites as well as numerous resin and polymers. However, there are many processing and commercial challenges to surmount on an almost daily basis. From the printing and converting perspective speed to market considerations rank highly, quality must be maintained at all time and the integrity of the product must be maintained, critical at all times but especially when it comes to products subject to sterilisation processes or when food products are packed.

Selection of materials sometimes requires a degree of experimentation. Barrier resistance, heat stability, printability and much else besides need to be considered. With regard to producing a pack with clarity or a degree of transparency there are many clear barrier materials to choose from, including those that compare favourably in terms of barrier resistance to thin gauge aluminium foils and metallized films.

Protective requirement varies greatly; some applications require a barrier against oxygen and water vapour, some demand chemical resistance and protection from UV light. Still others need microbial barrier properties.

Formable barrier materials include ethylene vinyl alcohol (EVOH) co-extrusions. Clear barrier webs often benefit from the addition of various barrier coating. This is certainly the case when using an appropriately gauged bi-axially oriented polyester (OPET) film, a substrate noted for its strength, clarity, thermal stability and chemical resistance.

Coatings that enhance the performance of many materials include, silicon oxides, PVDC or polyvinylidene chloride and polyvinyl alcohol.

PVDC is sometimes made available as a discrete layered co-extruded film; more often than not it is applied inline as a barrier coating. PVDC has good oxygen and moisture resistance, though the degree of protection varies according to coating thickness. The same applies when PVOH or polyvinyl alcohol is deposited as a coating.

The search for packaging materials with clarity and barrier resistance is driven by the end user and the transport and storage requirements. If we consider in its narrowest sense of a barrier to oxygen, polyethylene and for example polypropylene have little to offer in the way of barrier resistance to oxygen, which affects the appearance, taste and texture of meat products, etc., EVOH, PVDC on the other hands provides the necessary resistance, without compromising on package film clarity.

RK Print Coat Instruments Ltd
Litlington, Royston, Hertfordshire SG8 0QZ 
www.rkprint.com sales@rkprint.com

Source: RK Print Coat Instruments Ltd