Liquid packaging board (LPB) is a versatile material used for various liquid packaging applications, with milk and juice packaging being the most common. LPB is used for two types of packages: brick and gable top.

Brick board is delivered to dairies in rolls, either in a flat form or in a tubular form with the longitudinal seal already made. The unique feature of the packaging process is that filling and forming of the package are done in one stage under a liquid surface. This eliminates the presence of gas in the package. Additionally, the contents of the package support the carton, allowing for the use of lower basis weight. Brick type packages are often aseptic, ensuring the safety and freshness of the product.

On the other hand, LPB for gable top packages, such as one-liter milk cartons, is delivered in blank form with the side seal already made. The bottom seal is made after the carton has been assembled, followed by the addition of liquid, and then the top seal is made. Gable top packages require higher basis weight LPB compared to brick packages.

The purity and cleanliness of the product are of utmost importance when it comes to milk and juice packaging. Therefore, only virgin fiber can be used for LPB production. To ensure a good package, high paperboard stiffness is necessary. This has led to the development of two-ply and three-ply (or even more) structures. Pulp with a high modulus of elasticity is used for the top and back plies, while pulp providing maximum bulk is used for the middle ply.

Since LPB goes through a converting operation where various layers of plastic and/or metal are added, it is delivered to converters from the board mill in roll form. LPB is a multi-ply product that can be coated or uncoated, depending on the end use. It can also be made of unbleached or bleached chemical pulp.

In conclusion, liquid packaging board plays a crucial role in the packaging of milk and juice. Its unique properties and manufacturing process ensure the purity and safety of the product. LPB is continuously evolving to meet the changing needs of the industry, providing efficient and reliable packaging solutions.