Packaging Technology and Engineering. Dipak Kumar Sarker

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77–79 GLS Metal‐backed glass (Cu, Ag, Au, respectively) Composites 81 C^a) Mixed media: paper/plastic Chilled grocery, drinks cartons 82 C^a) Paper and fibreboard with aluminium Pack liners 90–92 C^a) Plastic and metals Retortable pouches 95–98 C^a) Glass and metals Reinforced glass 99 C^a) Other

a) LDPE, LD polyethylene; PA, polyamide; PAN, polyacrylonitrile; PAP, paper; PC, polycarbonate; PET, polyethylene terephthalate; SAN, styrene–acrylonitrile.

      Numerical and abbreviation codes are also shown in Figure 8.2a(iv).

      1.2.2.1 The Meaning of Symbols on Packaging

A single cyclical arrow (), a circle based on an arrowed ‘ying‐yang’ symbol () found on the product packaging, and the more common centre‐filled codified three‐arrowed universal recycling symbol () represent an assurance that the producer of that packaging recognises the potential for the material to be reused or reworked (see Table 8.2 and Figure 8.1). The colour, exact form, and size of this triangular symbol () as well as the colour of the background may vary according to the packaging. The meaning of the symbols is given in Table 1.2. The symbols were initially used by the Society of the Plastics Industry (SPI) of the USA (founded in 1937) until it ceased activities under this name in 2010, when the body was renamed. The organisation was rebranded in 2016 as the Plastics Industry Association (PIA) and now sits as the authority on plastic materials, promoting the use of the eight ‘plastics’ symbols that have been adopted globally to aid recycling and recyclability. The RIC and international packaging material codes highlight that the packaging product is made from materials that can be recycled or indicate that any recycling of this material is not available at present. Recyclable plastics with RIC codes of 1/2/4/5 (mostly polyolefins) are habitually recycled. However, plastics assigned 3/6/7 are rarely recycled, possibly because of the evolution of toxic waste, with category 7 indicating the use of a mixed‐medium material (other than polymeric materials 1–6), which is currently inaccessible to recycling practices. Other common groupings of materials are 20–39 for paper and cardboard material, 40–49 for metal material, and 70–79 for glasses (Table 1.2).

      Other information shown on the pack in recent times can include ‘made from recycled …’ or shows the packaging origins by bearing the caption ‘is made in part or in full from recycled material’. Where only part of the material of the product is based on recycled materials this is often indicated in a manner such as ‘label made from’ or ‘core made from’ in the case of white‐lined paperboard. Packaging manufacturers or companies that have a code number from the relevant body such as the Department for Environment, Food and Rural Affairs in the UK or the Ministry of Commerce and Industry in India may use the symbol in the way it is allocated to the product varying by the country holding the licence. Some products also bear on the pack or on the label an indication of other properties of the contents. These can include pictorial indications if the product contains flammable products such as butane, contains pressurised gas, contains toxic products (), or may cause infection or irritation. The product packaging also indicates if it is made from compostable materials and therefore is a recognised compostable product, such as the compressed paper egg boxes used in the UK (according to EN 13432). The complex variety of packaging materials [8] used for consumable and non‐consumable products serves a multitude of functions, but the primary importance is chemical, microbiological, and physical protection. Current awareness of packaging use, design, and resource utilisation and ultimately of sustainability [9–11] is an important issue and one that defines current, and will increasingly define future, use.

      1.2.2.2 Glass Packaging

      Washed sand is the main ingredient needed for the fabrication of most types of glass. However, glassy materials produced using only pure silica result in a glass that is too fragile for commercial handling. Consequently, soda (sodium oxide) is added to increase the durability and simultaneously decrease the melting point temperature, making the product easier to handle. Limestone minerals, such as dolomite (calcium carbonate), are incorporated into the sample to increase the chemical resistance of the glass and confer an inertness to a corrosive product. Secondary additions, such as broken pieces of preformed glass (cullet), are further added to this ‘combination’ during production; this is then heated to approximately 1500 °C and shaped into the desired glass packaging. Using broken cullet that has been through certain recycling processes provides technical, environmental, and economic advantages over virgin materials.

Glass packaging has a natural gloss and sheen and is smooth and easy to clean or rinse and dry, so it represents a convenient material for many applications. It is also aesthetically pleasing to the eye because it is optically transparent and can be fine‐tuned to possess a range of optical properties. Given the high amount of energy required for original manufacture it is convenient that glasses can be both reused and recycled. Many pharmaceutical and liquor producers prefer the material because of its inertness and non‐reactivity to chemicals but also because of its high gas and water barrier properties, combined with its ability to withstand very high pasteurisation and sterilisation temperatures. The technical properties of glass have also increased as a result of new techniques discovered for cutting, carving, moulding, and surface engraving. Using computer‐programmed cutting to form numerous designs, including same strength but lightweight versions of vessels, is now possible. Glass beer bottles account for nearly 55% of glass packaging usage followed by 18% for food, 12% for wine, alcoholic drinks, and liquor, 7% for soft drinks, and others,

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