What Materials are Used to Make Cardboard?

Pine trees are the primary ingredient in cardboard boxes.

Corrugated cardboard is a commonly used type of commercial packaging that consists mostly of pine trees that are grown specifically for this use. Only the tree trunks are used. They are processed at a pulp mill with various chemicals that break down wood chips into a mass that can be further made into sheets and boxes.

Pulping and Gluing

The tree trunks are reduced to wood chips, which are mixed with a variety of alkaline materials like sodium hydroxide, sulfates, sulfides and sulfites. Old cardboard can also be recycled and added to the pulp to make new cardboard. The alkaline chemicals turn the wood chips into a fibrous pulp, which is pressed, dried and rolled into sheets called kraft paper. Large quantities of corn starch powder are then mixed with water and other chemicals and spread on the formed sheets to glue components together to make corrugated cardboard. Heat is then used to cure the glue. The strength of the cardboard can vary according to a customer's needs.

Additional Materials

Inks of various colors are used for printing text, logos and graphics on the cardboard. Blank cardboard sheets are fed through fabrication machines with rollers, printing dies and die-cutting patterns. The machines also trim and score them. Then they are folded and glued and, finally, stacked, banded and wrapped. In addition, waxes made from vegetable oils or paraffin can be applied if grease or water-resistance is required.

References

• Pennsylvania Department of Environmental Protection: Other Paper Products
• Advameg: Corrugated Cardboard