The quality and resistance of a corrugated cardboard for packaging depends on the correct arrangement of the fibers and their size

How many times have we received, delivered at home, the products we bought on the internet enclosed in a box of cardboard, how many times in our company we use boxes, more or less large, to pack our products for sale, how many times we order by putting our things in cardboard boxes.

A type of convenient packaging, simple to use, long-lasting and also circular, as we easily handle corrugated cardboard boxes made with mainly recycled and recyclable paper.

In a more professional environment, therefore in the company, the quality of the packaging, whatever they may be, is of substantial importance, not only to present our products to customers, but to protect them during transport and storage in the warehouse.

How is recycled corrugated cardboard produced?

To create the finished product we start from its origin, so let's see how the sheets that will make up the recycled corrugated cardboard are made >, taking a step back to the paper mill.

In fact, it is there where the story begins, using, as raw material, the cardboard that comes from separate collection, which makes up the preeminent part of the recipe, then adding a small part of virgin paper fibers, to increase the quality of the finished product.

The type of recipe described does not exhaust the possibilities of finding other blends, as a corrugated cardboard can also be produced 100% with recycled material or with lower percentages of it.

Once the raw material has been inserted into the processing plant, water and other substances suitable for the treatment are added, thus starting a mixing of the raw material which leads to the creation of a fluid paste, in which we find an element of crucial importance for the quality of the future finished product which is fibers.

In fact, both the recycled cardboard and the natural raw material, which comes from trees, contain different types and form the backbone of future boxes in corrugated cardboard.

Once the paper pulp is made, it is spread out, in thin layers, which vary according to commercial requests, on work surfaces to then be sent to the drying of the sheets.

Once the correct drying has been achieved, the flat sheets are placed between a corrugated one, specially made through the use of a mechanical folding action assisted by steam. The various layers will then be glued together using vegetable glues derived from potato starch or corn starch.

How the direction of the fibers is formed and why it is so important

During the creation of the pasta, the most important game regarding future quality is played through the movement of the machine and the presence of water of the cardboard, in fact, with this operation the direction of the fibers is formed which, together with their length, will determine the qualitative result of the product.

The fibers are, as mentioned, an armor for the sheet of paper or cardboard, the bearing tool of the product and, their arrangement determines their one-way or two-way mechanical strength.

In fact if the fibers are oriented in a parallel way it is possible to tear the sheet in the direction of the same, but it is difficult and irregular in the opposite direction.

Furthermore, if the fibers do not have a parallel pattern but unevenly distributed, the mechanical resistance is obtained in both directions of tearing.

This does not only apply to the division of the two flaps of the cardboard or paper, but also to its ability to be folded, in fact if we do not consider the arrangement of the fibers, during the folding of a wing of the box, for example, this will be imperfect and difficult, both manually and using the packing machines.

What are the differences between using long fibers and short fibers

Not all fibers are the same: there are those that are thinner, longer, more irregular, very porous, not porous at all, with knots, of pointed or cylindrical shape and many others.

To simplify, with regard to which fiber would be better to use to produce a corrugated cardboard box, we can say that long fibers are the ones most suitable for purpose, as they have greater resistance and hardness, having to create a surface that is as rigid as possible.

For completeness we can indicate the short fibers are an excellent solution for creating soft and yielding papers, which are used for multiple uses.

Using recycled paper to produce recycled cardboard

As we have seen, a good quality paper for making packaging boxes must use a pulp that contains a sufficient amount of fibers long to reinforce the structure.

In order to arrive at the correct recipe, to contain costs and to contribute to the use of paper and cardboard waste that we produce every day, the production uses a good part of recycled cardboard.

The recycling operations involve, over time, a certain leaching of the fibers, with the consequence that their contribution in the recipe for the production of packaging cardboard, with the various treatment cycles, could decrease.

In this case it becomes necessary to resort to the addition of virgin fibers in order to balance the decrease caused by recycling.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.