Application of Laser Processing in Modern Flexible Packaging

The original concept for this form of laser processing was for the micro perforating cigarette tipping materials to create the cool draw concept. This is a current market and in the meantime over the past years MLT machine development also focused on other industrial processes such as perforation, scribing/ scoring and marking applications which are today in operation and in continuous demand worldwide.

MLT customers require turn-key, tailor-made solutions for their packaging needs not only in relation to the Laser process and machine configuration but also the technical and specialist advice regarding the necessary extraction and filter systems which is a very important topic in the food and hygiene market.

MLT offers customised laser solutions based on all key components both at the film producing and converting process (off-line) or on the packaging machines (online).

Micro-perforation:

Web material Laser Perforation Systems, can also be used to create ‘Micro holes’ for MAP – Modified Atmosphere Packaging, especially applicable to flexo or gravure printed film materials, a solution commonly used for the packaging of fresh and perishable goods such as vegetables, lettuce or herbs

Modified atmosphere packaging (MAP) of fresh food produce requires a completely different approach by the packaging industry which is used to developing packaging with barrier properties designed to exclude atmospheric oxygen and prevent migration of any component within the package to the outer surface of the packaging material.

Fresh produce, such a salads, fruits and vegetables are to some extent ‘alive’ for a specific ‘shelf life’ of the product and therefore technically still require oxygen for their metabolism. Conventional flexible packaging with regular barrier properties has not proved to be suitable in most cases. An alternative packaging is required whose gas transmission properties are precisely matched to the ‘gas out’ requirements of the product.

As the industry for freshly supplied produce has grown larger and more sophisticated, so the requirements from the packaging must develop accordingly.

Films with holes or pores admit O2 and CO2 at similar rates. Therefore, the ratios of gases that can result inside such packages are limited. It is impossible to achieve low O2 (1-5%) without accumulating high CO2 (15-20%). Thus, these films are applicable only for those products that tolerate high CO2 without experiencing premature decay.

Micro-perforated films can offer the possibility to tailor the OTR ( oxygen transfer rate ) to suit the produce to be packaged. The holes are typically from 50 microns in diameter and can be spaced at the required pitch.

Perforating speeds up to 400 m/min is possible with the MLT unique optical multiplexing technology used in MAP applications

Laser Scanning

So called ‘scanning’ laser systems can produce at high speeds (compared to punching/die-cutting systems) ‘Macro holes’ provided as a simple packaging airing system e.g. Flow-Wrap of trays.

Scanner technology enables film processing at web speeds of up to 200 m/min.

MLT Laser Scribing/Scoring Systems can process all established mono and multilayer film combinations. MLT can offer both an offline solution for the film slitter/rewinder process or alternatively as an online solution during the actual packaging process, enabling, through our Laser technology, defined material/film weakening in a specific location of the final package.

Typical examples are the “Easy Opening” solutions for instant products, such as coffee, soups and pet food which increasingly prefer the opening of their packaging without tool or tear strip.

More complex opening functions for convenience-food applications such as the defined/timed opening of microwave packaging during heating are still to be further established in the market.

In order to achieve an Easy Opening feature, materials can be processed in Machine Direction (MD), Cross Direction (CD) or in all variations of Free-Form contour scribing. Laser Scoring/Scribing can also be implemented to create paperboard container fold-lines. The selected weakening of materials can be adjusted with a high level of precision ensuring the barrier properties are not damaged during the scribing process.

Laser Marking/security systems:

Laser Marking Systems are also incorporated as solutions for product safety and anti-plagiarism. Web materials, and other materials with smooth surfaces, can be Marked either during the “on-the-fly” or the “interrupted-cycle” process which enables the superimposing of labels, security marks, barcodes and number-combinations.

A classic example is the safety-code marking of cigarette packets.

But maybe you have your own idea for using laser technology?

Lawrence Wild, Edlon Machinery Ltd, Maple House, Potters Bar, EN6 5BS Email: wild@edlonmachinery.co.uk
Tel: 0044 (0)1707 827957

Frank R Wagner, MLT Micro Laser Tech, D – 85551 Kirchheim, Germany

Email: fwagner@microlasertech.de
Tel: 0049 (0) 89 901196 725