Liquid packaging board is a multi-plypaperboard with high stiffness, strongwet sizing and a high barriercoating, e.g.plastic. Only virginpaper fibers are used. The barrier coating must hold the liquid and prevent migration of air and flavors through the paperboard.[1]
A liquid packaging board might be up to five plies and is formed on a multi-plypaper machine with online coating. The most common is to use three plies with abasis weight of about 300 g/m2.[2] The base or middle ply is normally made ofpulp from bleached or unbleached chemical pulp,chemi-thermo-mechanical pulp (CTMP) orbroke (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. Wheninduction welding is employed analuminum foil layer is used for barrier protection and for heating.[3] 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 theprinting applications. Liquid packages are normallyheat sealed.
Cartons filled with short-shelf-lifedairy products use board that are barrier coated on both sides with one layer of low densitypolyethylene. For long-shelf-life products it is common to usealuminium foil as barrier coating together with polyethylene. Commonly theplastic coating on the top side is 12 - 20 g/m2 and on the reverse side 15 - 60 g/m2.[2]
Sanitary andaseptic processing of food contact products are critical.[4]
Liquid Packaging Board (LPB) is traditionally associated with beverage packaging, including formilk,juiceboxes and other dairy products, but its applications extend beyond just liquids, encompassing a broad range of uses due to its strength, barrier properties, and versatility.
Liquid packaging board is used for two package types: brick and gable topcartons.[citation needed]
