What is cardboard made of?

What is Cardboard Made Of?

Introduction: If you're curious about what cardboard is made of and how it can be recycled, this article is for you. Cardboard consists of two primary materials: Flute and Liners. Both of these materials originate from trees that are pulped.

Flute

Flute is the angular material between the liners of cardboard boxes, typically made from recycled paper. This structure gives cardboard its strength and rigidity.

Liners

Liners are the sheets between which the flute is sandwiched. There are two types of liners: the inner liner, known as test paper, and the outer liner, known as Kraft paper. Test paper liners are usually made from hardwood trees like oak and chestnut, or recycled paper, making them more affordable but rougher in quality. In contrast, the outer liner is made from softwood trees like pine, offering a smoother surface and better durability. This outer layer is also more water-resistant, making it ideal for printing and external exposure.

The two types of liners and the flute are glued together using a corrugator machine. Hot steam is sprayed on the paper, allowing it to be pressed and bonded. The corrugated cardboard is then cut to size, and designs such as handles and flaps are added using trimmers or die-cutters. Finally, the cardboard boxes are folded and assembled, with any leftover fragments being recycled.

Can Cardboard Be Recycled?

Yes, cardboard is one of the most extensively recycled materials. Here’s how the process works:

Sorting

The first step in recycling cardboard is sorting. Cardboard is categorized based on its quality and intended use, such as food packaging or shipping boxes. After sorting, the cardboard is shredded into small pieces.

Pulping

The shredded cardboard is mixed with water in large tanks, turning it into a pulp.

Filtration

The pulp is filtered to remove impurities like tape, plastic, and glue. A centrifugal process helps in this, followed by a de-inking process to remove any chemicals and ink.

More Addition of Water

More water and chemicals are added to the pulp to enhance its durability and water resistance. The mixture is then stirred and pressed.

Vacuum & Drying

The pulp is dried using heating and vacuum rollers, giving it a sturdy, sheet-like structure. Additional layers can be added depending on the type of cardboard being produced, such as double-walled or triple-walled cardboard.

The Final Stage

After drying, the cardboard is passed through rollers with small projections to create a corrugated texture, if needed. It is then cut and shaped into various sizes and forms, ready for use.

By following these steps, cardboard is efficiently recycled, reducing waste and supporting eco-friendly practices.