Manufacturing technology of the corrugated cardboard

Imagine you have a seemingly trivial carton in front of you. Have you ever thought that there is a need for a process that requires patience, meticulousness and thorough knowledge from many areas, in order for it to exist?

Corrugated cardboard is the combination of two sheets of paper called “cover” glued to a corrugated paper called “core“. These three layers of paper are assembled in a way that gives the overall structure a much better strength than the one in each layer.

This construction makes a series of connected arches, which are known for their great ability to support weights.

Plain layer paper (cover)

Kraftliner

Monolayer:

Multilayer (double layer):

Testliner
Monolayer:

Multilayer:

Testliner 1: the outer layer is 100% cellulose and the support ayer 50% cellulose and 50% waste paper.
Testliner 2: the outer layer and the support layer are 100% produced from paper waste made from cardboard packaging.
Testliner 3: the outer layer 100% of paper waste made from cardboard packaging and the support layer 100% of waste mixture.

Corrugated layer paper

The corrugated layer paper is the main component of the corrugated board strength structure, through its sinusoidal shape and rigid bonding points with the cover (plain) paper layers. The main resistance characteristic of the core paper is the corrugating resistance of the corrugations.

SC (semichemical)

W (wellenstoff)

Adhesives

For gluing the corrugated cardboard, natural or synthetic adhesives are used. Starch provides the best conditions for glue manufacturing, for the cost and solder strength.

Advantages of starch glue:

The solder strength is high and the starch glue can be used at high speeds of the corrugated cardboard machine.
It is easy to be prepared and is not toxic.
Dry starch from the bonding area is not abrasive for corrugated cardboard manufacturing machines.
It can be easily removed from the equipment.
Allows easy collapsing of corrugated paperboard.

Disadvantages of starch glue:

Requires rigorous temperature control in the soldering zone, namely reaching the gelling point, otherwise the solder strength will be low.
Excess water introduced with relatively large amount of glue due to low solids content may cause cardboard marking or curvature, therefore, to remove water, the corrugated cardboard machine must be provided with a relatively developed drying area.
Starch is a nutrient medium for microorganisms whose activity causes the solder resistance to decrease.

Corrugated cardboard machine – components