Liquid packaging board is a multi-ply

paperboard Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker (usually over 0.30 mm, 0.012 in, or 12 points) than paper and has certain superior attribute ...

with high stiffness, strong wet sizing and a high barrier coating, e.g.

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

. Only virgin paper fibers are used. The barrier coating must hold the liquid and prevent migration of air and flavors through the paperboard.

Manufacture

A liquid packaging board might be up to five plies and is formed on a multi-ply paper machine with online coating. The most common is to use three plies with a basis weight of about 300 g/m². The base or middle ply is normally made of pulp from bleached or unbleached chemical pulp, CTMP or ''broke'' (waste paper from a paper machine). CTMP gives more bulk and stiffness. The top ply (inside) is made of bleached chemical pulp. The barrier coating depends on the application and might be applied on both sides. When induction welding is employed an aluminum foil layer is used for barrier protection and for heating. The back side of the board is the printing side and might have an extra ply made from chemical pulp of quality that is suitable for the

printing Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ...

applications. Liquid packages are normally heat sealed. Cartons filled with short-shelf-life

dairy products Dairy products or milk products, also known as lacticinia, are food products made from (or containing) milk. The most common dairy animals are cow, water buffalo, nanny goat, and ewe. Dairy products include common grocery store food items in ...

use board that are barrier coated on both sides with one layer of low density

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including ...

. For long-shelf-life products it is common to use

aluminium foil Aluminium foil (or aluminum foil in North American English; often informally called tin foil) is aluminium prepared in thin metal leaves with a thickness less than ; thinner gauges down to are also commonly used. Standard household foil is typ ...

as barrier coating together with polyethylene. Commonly the plastic coating on the top side is 12 - 20 g/m² and on the reverse side 15 - 60 g/m². Sanitary and aseptic processing of food contact products are critical. Liquid packaging board is used for two package types: brick and gable top cartons.

Applications

*Packaging for beverages. The most common applications are

milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modulati ...

and juicebox packaging.

References

{{packaging Paperboard Packaging materials

Manufacture

Applications

See also

References