Product decoration technologies: flexible packaging

However, where the packaging itself comes into contact with food products, either directly or indirectly, there are numerous rules and regulations in place to protect the consumer and to ensure that inks, adhesives and other materials do not migrate into the product, or contaminate them in any way. These issues will be highlighted in this article.

We will also explore a number of the main flexible packaging systems in use and their role as a carrier of product decoration and branding, in a variety of market sectors.

MARKETS FOR FLEXIBLE PACKAGING

The largest sector of the flexible packaging market are for applications in food and retail, but other non-food sectors are growing fast (Figure 8.1). 

Major applications for flexible packaging are diverse and include the following;

• Multi-colored frozen food packs

• Sweet wrappers

• Confectionary packs – e.g. Mars wrappers etc.

• Garden centre and horticultural packs – fertilizer, bark, grass seed etc.

• DIY packs – wallpaper paste, plaster etc

• Stand-up pouches – washing liquids, detergents, soups etc.

• Sachets

• Lidding for yogurt, cream, dessert, pots etc.

• Agricultural packs – feeds, seeds etc.

Some product categories have notably shifted almost entirely to filmic packaging, for example baby food and some tobacco products.

The key end-use markets for flexible packaging are featured in the chart (see Figure 8.2).

THE CONVERTING PROCESS

A typical converting process for flexible packaging from material through to the end-product is illustrated in Figure 8.3 below. Each of these steps will be covered in the paragraphs that follow.

Peelable seal lids require a polymer layer on the inside to facilitate the heat sealing.

Some lidding applications require a heat seal coating applied to the film construction. The coated film passes over a pre-heat station where it warmed before it is sealed to the tray or pack, via a sealing bar or platen set at a desired heat, pressure and dwell time. The sealed tray or pack is then die-cut to shape.

Pot applications such as yogurts use heat seal pre-cut lids or diaphrams matched to the shape of the container.

Form Fill Seal (FFS)

Form-fill-seal (FFS) machines are used to form the package, fill it with a wet or dry product and seal it closed. Most FFS systems use a roll of flexible packaging film which is shaped and sealed to form the primary package, such as a wrapper or pouch (Figure 8.13).

FFS machines can be positioned either vertically or horizontally. Vertical machines form and cut packages. The product is then dropped into the package before final sealing (Figure 8.14).

Horizontal machines are used in cases where dropping a fragile product (such as a cake or biscuit) vertically may cause damage and instead the product is placed into the package horizontally (Figure 8.15).

FFS machines are able to fill the flexible pack from either the top or the side. In most cases heat sealers apply heat to the sides of the package and melt the substrate material together to form a seal.

Ultrasonic sealing is a new development which tends to be used for heat-sensitive products and permits sealing through liquids.

Sachets

A variety of materials can be used for sachet packing including aluminium foil, paper backed foil and PET foil.

Individual packs can be designed and printed in a range of colors to reinforce branding, as well as displaying all the required regulatory and product information.

Many different sizes of sachets can be filled with a range of products including powders, tablets and capsules or liquid.

Packaging machines are used which take flexible packaging material, to form a package which is then filled and sealed in a sequence of operations to form a three or four side sealed sachet. The process is similar to that illustrated in Figure 8.6.

There are two basic types of sachets, a fin seal type which is a face-to-face seal around the pack and a pillow style which is a crimp seal on the top and bottom edges and a flat seam running down one side.

The majority of machines used for these type of operations, are of the vertical form fill seal type, although horizontal form fill seal equipment is sometimes employed.

ALUMINIUM FOIL BOTTLE CAPS AND NECK FOILS

There are many types of bottle cap liners in use. Whilst they can be printed, their main function is to seal and protect the contents of the pack.

A popular seal liner is the induction seal which contains a foil laminate (known as an inner-seal) which is welded to the top lip of jars and bottles and creates a hermetic, tamper evident seal. Aluminium foil’s ability to be a total barrier to light, atmosphere and liquids is the principle reason for its use in caps, capsules and lids.

The sealing process takes place after the filling and capping operation. The capped containers pass underneath an induction sealing system which produces an electromagnetic current and the foil laminate generates electrical resistance, heating the foil. The hot foil in turn melts a polymer coating on the inner-seal. The heat, coupled with the pressure of the cap, causes the inner-seal to bond to the lip of the container.

Heat seal closures are compatible with the wide variety of plastic containers – PS, PP, PE, PVC and PET.

Aluminium neck foiling is used on a large scale particularly for premium brand beers, wines and champagnes to convey the impression of high quality.

Unsupported neck foils are often printed and are totally malleable, and can cover curved and shaped areas of the bottle neck and closure, to create a decorative finish and provide evidence of tampering. Neck foils are frequently embossed giving a distinctive appearance (Figure 8.16).

FOOD LABELING APPLICATIONS

In the food sector consumers are increasingly concerned about labels and/or packaging contaminating products. This concern is heightened in instances where packaging materials are in direct contact with food contents, but many of the issues relating to migration apply to all types of labeling and packaging.

Most countries have standards which determine which label and packaging materials may come into direct contact with food-stuffs and human skin. These products are prohibited along with those where there may be some transfer or migration of substances to food. The label user and/or label manufacturer are held liable for any failure on their part to comply with standards.

The labeling requirements for foods are set out in the relevant EU, FDA and national regulations around the world. They generally relate to most prepared foods, such as canned and frozen foods, breads, cereals, snacks, desserts, etc. Nutritional labeling may be voluntary, while other foods may have more detailed separate labeling requirements.

There are a number of directives and regulations governing food labeling, but these are complex and not always easy to understand. The EU started to harmonize legislation on food contact materials several years ago, but fully harmonized legislation does not yet exist for all materials.

Much of the basic regulatory background is contained in Regulation (EC) N° 1935/2004 and in particular article 15 of this regulation.

The article lays down common rules for packaging materials which come, or may come, into contact with food, either directly or indirectly. It also seeks to protect human health and consumers’ interests throughout the European Economic Area. It covers a wide range of different materials, including all papers and boards, plastics, inks, adhesives and coatings Any substances which can reasonably be expected to come into contact, or which can transfer their constituents to food are covered by the regulation. It seeks to ensure that the labeling of foods ‘shall not mislead the consumer’.

In America the FDA (US Food and Drugs Administration) is the U.S. federal agency responsible for ensuring that foods are safe, wholesome and sanitary; that human and veterinary drugs, biological products, and mechanical devices are safe and effective; that cosmetics are safe; that electronic products that emit radiation are safe.

The FDA also ensures that these products are honestly, accurately and informatively represented to the public, including issuing regulations governing the use of self-adhesive labels for contact with foodstuffs (FDA 175.125 for direct contact, and FDA 175.105 for indirect contact).

The U.S. Federal Food, Drug and Cosmetic Act (FFDCA) defines food ‘labeling’ very broadly. It covers all labels and other written, printed, or graphic matter upon any article or any of its containers or wrappers, or accompanying such article. The term 'accompanying' extends to tags, leaflets, circulars, booklets, brochures, instructions, and even websites.

The Nutrition Labeling and Education Act (NLEA), which amended the FFDCA, requires most foods to show specific nutrition and ingredients on the label. Food, beverage and dietary supplement labels that show nutrient content claims (for example ‘low fat’ or ‘contains vitamin XYZ’) and certain health messages have to comply with specific legal requirements.

Furthermore, the Dietary Supplement Health and Education Act (DSHEA) has amended the FFDCA, in part, by defining ‘dietary supplements’. It also adds specific labeling requirements for dietary supplements, and provides for optional labeling statements).

A US government advisory body exists to check compliance of any label with current rules. This service (which must be paid for) is recommended for manufacturers and label/leaflet vendors. A recent regulation (May 2016) changes US requirements regarding health criteria to be mentioned on labels.

Figure 8.17 highlights some of the most important aspects of food labeling regulations and directives.

MIGRATION

There are rules and regulations in place to ensure that inks, adhesives and other materials do not migrate into the product.

For Europe, regulation (EC) No 1935/20041 requires that materials and articles which, in their finished state, are intended to be brought into contact with foodstuffs, must not transfer any components to the packed foodstuff in quantities which could endanger human health, or bring about an unacceptable change in the composition or deterioration in organoleptic properties.

Figure 8.18 highlights some of the key migration issues to be considered when labeling or packaging food.

Although the risk that chemicals may leach through labels and packaging is real, the fear arises through most people’s ignorance of what chemicals there are in ink. As a result, label converters are turning pre-emptively to more expensive low-migration inks.

Some ink manufacturers are promoting UV LED inks not only for the energy economy, but also because this drying technology can be better controlled than traditional mercury lamp drying.

There has been some concern about the risk of contamination through mineral oils contained in substrates. Paper materials however are mostly made from virgin fibers, and synthetic substrates have (so far) been less often accused, and are available in ‘high barrier’ options from several producers.

Adhesives used for self-adhesive labels can also be a potential source of migration and contamination, particularly when these labels are applied directly to foodstuffs. The two most commonly used adhesives for pressure-sensitive labels are hotmelt and acrylic emulsion.

Nearly all adhesives stick because they contain resins, and the lower the resin content, the lower the initial tack. This problem is even more acute with filmic labels.

However recent developments using a multi-layer adhesive technology have resulted in a virtually resin-free adhesive, which can be used for filmic food labels as well as for moist or fatty surfaces.

Knowledge around barrier protection is crucial for servicing the market. Suppliers must be able to provide the right sealant for a given application and to support clients with 'fitness for use' testing.

CONCLUSION

One of the main factors driving the growth in flexibles is cost savings, particularly when flexibles are compared with labeled or decorated rigid packaging. Users of flexible can claim an improved carbon footprint, because of the weight and volume savings achieved. As mentioned previously migration and food labeling regulations need to be carefully considered in those sectors.

Recycling, environmental friendliness and sustainability have become issues for all packaging, providing the opportunity for new packaging materials development. As a result, continual improvements in polymer films, surface treatments, and coatings are yielding new packaging alternatives while respecting environmental impact.

Film structures are clearly moving to thinner laminations with stronger barriers and improved seal properties, which may require investments in servo-driven presses with special tensioning capabilities. At the same time, packaging machinery is being built to run faster.

In recent years the market for flexibles has been driven by innovative new origination, print and press technologies.

There is also a growing realization that narrow-web digital presses also have a significant role to play in meeting manufacturer’s demands for shorter runs, lead times, variable data and more product personalization.

Peelable seal lids require a polymer layer on the inside to facilitate the heat sealing.

Some lidding applications require a heat seal coating applied to the film construction. The coated film passes over a pre-heat station where it warmed before it is sealed to the tray or pack, via a sealing bar or platen set at a desired heat, pressure and dwell time. The sealed tray or pack is then die-cut to shape.

Pot applications such as yogurts use heat seal pre-cut lids or diaphrams matched to the shape of the container.

Form Fill Seal (FFS)

Form-fill-seal (FFS) machines are used to form the package, fill it with a wet or dry product and seal it closed. Most FFS systems use a roll of flexible packaging film which is shaped and sealed to form the primary package, such as a wrapper or pouch (Figure 8.13).

FFS machines are able to fill the flexible pack from either the top or the side. In most cases heat sealers apply heat to the sides of the package and melt the substrate material together to form a seal.

Ultrasonic sealing is a new development which tends to be used for heat-sensitive products and permits sealing through liquids.

Sachets

A variety of materials can be used for sachet packing including aluminium foil, paper backed foil and PET foil.

Individual packs can be designed and printed in a range of colors to reinforce branding, as well as displaying all the required regulatory and product information.

Many different sizes of sachets can be filled with a range of products including powders, tablets and capsules or liquid.

Packaging machines are used which take flexible packaging material, to form a package which is then filled and sealed in a sequence of operations to form a three or four side sealed sachet. The process is similar to that illustrated in Figure 8.6.

There are two basic types of sachets, a fin seal type which is a face-to-face seal around the pack and a pillow style which is a crimp seal on the top and bottom edges and a flat seam running down one side.

The majority of machines used for these type of operations, are of the vertical form fill seal type, although horizontal form fill seal equipment is sometimes employed.

ALUMINIUM FOIL BOTTLE CAPS AND NECK FOILS

There are many types of bottle cap liners in use. Whilst they can be printed, their main function is to seal and protect the contents of the pack.

A popular seal liner is the induction seal which contains a foil laminate (known as an inner-seal) which is welded to the top lip of jars and bottles and creates a hermetic, tamper evident seal. Aluminium foil’s ability to be a total barrier to light, atmosphere and liquids is the principle reason for its use in caps, capsules and lids.

The sealing process takes place after the filling and capping operation. The capped containers pass underneath an induction sealing system which produces an electromagnetic current and the foil laminate generates electrical resistance, heating the foil. The hot foil in turn melts a polymer coating on the inner-seal. The heat, coupled with the pressure of the cap, causes the inner-seal to bond to the lip of the container.

Heat seal closures are compatible with the wide variety of plastic containers – PS, PP, PE, PVC and PET.

Aluminium neck foiling is used on a large scale particularly for premium brand beers, wines and champagnes to convey the impression of high quality.

Unsupported neck foils are often printed and are totally malleable, and can cover curved and shaped areas of the bottle neck and closure, to create a decorative finish and provide evidence of tampering. Neck foils are frequently embossed giving a distinctive appearance (Figure 8.16).

FFS machines are able to fill the flexible pack from either the top or the side. In most cases heat sealers apply heat to the sides of the package and melt the substrate material together to form a seal.

Ultrasonic sealing is a new development which tends to be used for heat-sensitive products and permits sealing through liquids.

Sachets

A variety of materials can be used for sachet packing including aluminium foil, paper backed foil and PET foil.

Individual packs can be designed and printed in a range of colors to reinforce branding, as well as displaying all the required regulatory and product information.

Many different sizes of sachets can be filled with a range of products including powders, tablets and capsules or liquid.

Packaging machines are used which take flexible packaging material, to form a package which is then filled and sealed in a sequence of operations to form a three or four side sealed sachet. The process is similar to that illustrated in Figure 8.6.

There are two basic types of sachets, a fin seal type which is a face-to-face seal around the pack and a pillow style which is a crimp seal on the top and bottom edges and a flat seam running down one side.

The majority of machines used for these type of operations, are of the vertical form fill seal type, although horizontal form fill seal equipment is sometimes employed.

ALUMINIUM FOIL BOTTLE CAPS AND NECK FOILS

There are many types of bottle cap liners in use. Whilst they can be printed, their main function is to seal and protect the contents of the pack.

A popular seal liner is the induction seal which contains a foil laminate (known as an inner-seal) which is welded to the top lip of jars and bottles and creates a hermetic, tamper evident seal. Aluminium foil’s ability to be a total barrier to light, atmosphere and liquids is the principle reason for its use in caps, capsules and lids.

The sealing process takes place after the filling and capping operation. The capped containers pass underneath an induction sealing system which produces an electromagnetic current and the foil laminate generates electrical resistance, heating the foil. The hot foil in turn melts a polymer coating on the inner-seal. The heat, coupled with the pressure of the cap, causes the inner-seal to bond to the lip of the container.

Heat seal closures are compatible with the wide variety of plastic containers – PS, PP, PE, PVC and PET.

Aluminium neck foiling is used on a large scale particularly for premium brand beers, wines and champagnes to convey the impression of high quality.

Unsupported neck foils are often printed and are totally malleable, and can cover curved and shaped areas of the bottle neck and closure, to create a decorative finish and provide evidence of tampering. Neck foils are frequently embossed giving a distinctive appearance (Figure 8.16).

FOOD LABELING APPLICATIONS

In the food sector consumers are increasingly concerned about labels and/or packaging contaminating products. This concern is heightened in instances where packaging materials are in direct contact with food contents, but many of the issues relating to migration apply to all types of labeling and packaging.

Most countries have standards which determine which label and packaging materials may come into direct contact with food-stuffs and human skin. These products are prohibited along with those where there may be some transfer or migration of substances to food. The label user and/or label manufacturer are held liable for any failure on their part to comply with standards.

The labeling requirements for foods are set out in the relevant EU, FDA and national regulations around the world. They generally relate to most prepared foods, such as canned and frozen foods, breads, cereals, snacks, desserts, etc. Nutritional labeling may be voluntary, while other foods may have more detailed separate labeling requirements.

There are a number of directives and regulations governing food labeling, but these are complex and not always easy to understand. The EU started to harmonize legislation on food contact materials several years ago, but fully harmonized legislation does not yet exist for all materials.

Much of the basic regulatory background is contained in Regulation (EC) N° 1935/2004 and in particular article 15 of this regulation.

The article lays down common rules for packaging materials which come, or may come, into contact with food, either directly or indirectly. It also seeks to protect human health and consumers’ interests throughout the European Economic Area. It covers a wide range of different materials, including all papers and boards, plastics, inks, adhesives and coatings Any substances which can reasonably be expected to come into contact, or which can transfer their constituents to food are covered by the regulation. It seeks to ensure that the labeling of foods ‘shall not mislead the consumer’.

In America the FDA (US Food and Drugs Administration) is the U.S. federal agency responsible for ensuring that foods are safe, wholesome and sanitary; that human and veterinary drugs, biological products, and mechanical devices are safe and effective; that cosmetics are safe; that electronic products that emit radiation are safe.

The FDA also ensures that these products are honestly, accurately and informatively represented to the public, including issuing regulations governing the use of self-adhesive labels for contact with foodstuffs (FDA 175.125 for direct contact, and FDA 175.105 for indirect contact).

The U.S. Federal Food, Drug and Cosmetic Act (FFDCA) defines food ‘labeling’ very broadly. It covers all labels and other written, printed, or graphic matter upon any article or any of its containers or wrappers, or accompanying such article. The term 'accompanying' extends to tags, leaflets, circulars, booklets, brochures, instructions, and even websites.

The Nutrition Labeling and Education Act (NLEA), which amended the FFDCA, requires most foods to show specific nutrition and ingredients on the label. Food, beverage and dietary supplement labels that show nutrient content claims (for example ‘low fat’ or ‘contains vitamin XYZ’) and certain health messages have to comply with specific legal requirements.

Furthermore, the Dietary Supplement Health and Education Act (DSHEA) has amended the FFDCA, in part, by defining ‘dietary supplements’. It also adds specific labeling requirements for dietary supplements, and provides for optional labeling statements).

A US government advisory body exists to check compliance of any label with current rules. This service (which must be paid for) is recommended for manufacturers and label/leaflet vendors. A recent regulation (May 2016) changes US requirements regarding health criteria to be mentioned on labels.

Figure 8.17 highlights some of the most important aspects of food labeling regulations and directives.

MIGRATION

There are rules and regulations in place to ensure that inks, adhesives and other materials do not migrate into the product.

For Europe, regulation (EC) No 1935/20041 requires that materials and articles which, in their finished state, are intended to be brought into contact with foodstuffs, must not transfer any components to the packed foodstuff in quantities which could endanger human health, or bring about an unacceptable change in the composition or deterioration in organoleptic properties.

Figure 8.18 highlights some of the key migration issues to be considered when labeling or packaging food.

Although the risk that chemicals may leach through labels and packaging is real, the fear arises through most people’s ignorance of what chemicals there are in ink. As a result, label converters are turning pre-emptively to more expensive low-migration inks.

Some ink manufacturers are promoting UV LED inks not only for the energy economy, but also because this drying technology can be better controlled than traditional mercury lamp drying.

There has been some concern about the risk of contamination through mineral oils contained in substrates. Paper materials however are mostly made from virgin fibers, and synthetic substrates have (so far) been less often accused, and are available in ‘high barrier’ options from several producers.

Adhesives used for self-adhesive labels can also be a potential source of migration and contamination, particularly when these labels are applied directly to foodstuffs. The two most commonly used adhesives for pressure-sensitive labels are hotmelt and acrylic emulsion.

Nearly all adhesives stick because they contain resins, and the lower the resin content, the lower the initial tack. This problem is even more acute with filmic labels.

However recent developments using a multi-layer adhesive technology have resulted in a virtually resin-free adhesive, which can be used for filmic food labels as well as for moist or fatty surfaces.

Knowledge around barrier protection is crucial for servicing the market. Suppliers must be able to provide the right sealant for a given application and to support clients with 'fitness for use' testing.

CONCLUSION

One of the main factors driving the growth in flexibles is cost savings, particularly when flexibles are compared with labeled or decorated rigid packaging. Users of flexible can claim an improved carbon footprint, because of the weight and volume savings achieved. As mentioned previously migration and food labeling regulations need to be carefully considered in those sectors.

Recycling, environmental friendliness and sustainability have become issues for all packaging, providing the opportunity for new packaging materials development. As a result, continual improvements in polymer films, surface treatments, and coatings are yielding new packaging alternatives while respecting environmental impact.

Film structures are clearly moving to thinner laminations with stronger barriers and improved seal properties, which may require investments in servo-driven presses with special tensioning capabilities. At the same time, packaging machinery is being built to run faster.

In recent years the market for flexibles has been driven by innovative new origination, print and press technologies.

There is also a growing realization that narrow-web digital presses also have a significant role to play in meeting manufacturer’s demands for shorter runs, lead times, variable data and more product personalization.