When the New York-born inventor Albert L. Jones developed the first corrugated board in 1871, no one could have imagined the significance that this lightweight, dimensionally stable and cost-effective packaging material would acquire over the decades. Corrugated board began a triumphal procession through various epochs and revolutionized logistics and the packaging world with lasting effect.

Today, corrugated board is the most widely used transport packaging worldwide. In Germany alone, more than two thirds of all goods packaged in corrugated board travel to recipients at home and abroad. The demand for corrugated board packaging solutions is correspondingly high. Sales of corrugated board as a recycled product have been rising continuously for decades.

No wonder, because with packaging made of corrugated board you achieve noticeable value-added contributions for functioning supply chains between industry, trade and consumers. This special packaging material combines low weight, excellent machinability and comparatively low material usage with effective product protection.

This is due not least to the special composition of the base materials. Fresh fibers and wood fibers are of particular importance in terms of high quality. The following article explains why this is so and why corrugated board is so popular as a material for a wide range of packaging solutions.   

That is why corrugated board is so popular as a packaging material

Corrugated board now consists of 76 percent recovered paper. The potential behind this is huge: around 5.4 million tons of recovered paper are processed into newly manufactured corrugated board every year. This means that in the German paper industry, 25 percent of total production is accounted for by the manufacture of corrugated board alone.

These figures impressively show the important role corrugated board plays in the transport of goods. In addition to the cost advantages compared to other types of packaging, corrugated board is particularly convincing due to its functional properties.

Corrugated board is a packaging material that can be made almost entirely from recycled raw materials. This makes it particularly sustainable!

Functional properties of corrugated board

Corrugated board has as its characteristic features high stability and strength. In addition, the material offers very good resistance and durability. This provides excellent product protection.

Thanks to the good stability, many boxes can be stacked on top of each other without crushing. This allows you to store your goods in a space-saving way. In the logistics sector, corrugated cardboard pallets with a load capacity of about two tons are not uncommon.

This high load-bearing capacity is achieved, among other things, by a construction with several layers of cardboard and different sized corrugations, which are glued on top of each other during production.

In the process, the flute provides the necessary stability on the one hand and a cushion that protects the packaged products on the other. In the course of special processing with various substances, manufacturers can even make the corrugated board resistant to water, acids, fire or insects to a certain extent.

The most commonly used types of shafts

In practice, the A, C, B and E flutes are mainly used for the production of packaging. The letters stand for different flute types and heights. 

• A (coarse flute): Shaft height 4.0 to 5.0 mm (pitch 7.9 to 10 mm)

• B (fine flute): Shaft height 2.2 to 3.1 mm (pitch 4.8 to 6.5 mm)

• C (medium flute): Shaft height 3.1 to 4.0 mm (pitch 6.5 to 7.9 mm)

• E (ultra-fine or microwave): Shaft height 1.0 to 1.9 mm (pitch 2.6 to 3.5 mm)

The environmental balance of corrugated board

Packaging made of corrugated board also has a good environmental balance. With the exception of traces of glue (provided it is not derived from substances such as corn, wheat or potato starch) and various substances used for impregnation, corrugated board is almost completely recyclable.

The adhesives and chemicals contained in the corrugated board can be reliably removed beforehand using special processes. Composting is also possible. However, you have to wait up to twelve months for complete decomposition.

Energy consumption for production and recycling is also rather low. The recycling of glass, for example, consumes far greater amounts of energy. The amount of chemical waste, which occurs to a greater extent in plastics recycling in particular, is also much lower.

How corrugated board is made

For the production of corrugated board or the required corrugated board base paper, waste paper and wood fibers are first shredded and then mixed and softened with the addition of water. Depending on the intended use, fillers, glues and dyes are added.

Corrugated board is made by gluing flat paper (the so-called cover paper) to corrugated paper (flute). The number of layers determines the stability and load-bearing capacity of the product. The number of layers determines the stability and load-bearing capacity of the product. Depending on the subsequent intended use, corrugated board can be produced with up to twelve layers.

Plane layers and corrugations always altern ate. The layers can consist of different basis weights and paper grades. In addition, the respective layers differ in the wave height and the wave pitch.

To give a corrugated board specific properties, manufacturers combine different paper grades, flute types and basis weights.

Wood fibers as primary raw material for the production of corrugated board

For the production of corrugated base papers (e.g. kraftliner), wood fibers are required just as for the production of paper raw materials. This is a primary raw material alternatively known as virgin fiber.

As a corresponding source of raw materials, manufacturers mostly resort to wood waste. These mainly come from broken, thinned and waste wood. Preferably, coniferous and hardwoods are used. Therefore, no forest areas have to be destroyed for the production of corrugated board.

This applies both to the production of local manufacturers and to imported corrugated base papers from producers in the USA, Canada and Scandinavia. The entire industry has been usingraw materials from sustainable and regulated forestry since as early as 1920.

Process for different fiber product

Primarily, three processes are available for the production of the fiber products required in each case:

• the mechanical process for the production of wood pulp
• the semi-chemical process for the production of semi-chemical pulp
• the chemical process for the production of pulp (cellulose)

While groundwood pulp and the mechanical process required for this do not play a significant role in the production of corrugated base paper, manufacturers use semi-chemical pulp to produce fluting paper and (sulfalt) pulp to produce kraftliner paper.

Cellulose or pulp canonly be produced from wood chips in a complex chemical cooking process (pulping). This process is known as the "alkaline sulfate process".

For the conversion, the manufacturers expose the wood to high temperatures of 170 to 190 degrees Celsius. After about four to six hours, a large part of the disturbing components of the wood dissolves under constant heat effect.

These substances are mainly lignin or resin. If you want to obtain white ceiling papers as an end product, you have to use bleaching agents during the manufacturing process. However, chlorine is not used. Instead, only oxygen is used.

It is true that corrugated board today is generally made from recycled corrugated base papers. However, kraftliner and semi-chemical pulp are still irreplaceable as base materials when the corrugated board is intended for packaging that is subject to high stresses.

For packaging with particularly low moisture absorption and high strength, paper grades with long wood fibers are required.

At a glance - these materials are crucial for the production of corrugated board

To give you a better overview of the possibilities for the production of corrugated board, we have listed the two different layers, the papers that can be used and the possible qualities.

1. the cover papers of corrugated board can be produced in these grades:

• Schrenz: Produced from mixed collector paper of comparatively low quality.
• Kraftliner: Represents the highest quality paper for the top layer; usually consists of at least 80 percent sulfate pulp.
• Testliner: Multilayer paper made from fiber materials of different types; however, the strength properties are not defined and guaranteed because the pulp content is not determined.

2. the fluting paper corrugated layers can be made in these qualities:

• Semi-chemical pulp: basis for the highest quality paper for the corrugating medium; very strong semi-chemical pulp paper in terms of consistency; made from wood fibers.
• Corrugated fabric: Made from the highest quality saddle paper
• Schrenz: Consists of mixed collector paper with the lowest quality.

This is how the wood fiber products for the production of corrugated board are created

Wood fibers are hardly recognizable components in wood. These can be defined as elongated wood cells that run in tree trunks and branches, preferably longitudinally oriented in the direction of growth.
The wood fibers, which consist mainly of cellulose and lignin, are mainly responsible for the strength of the wood. The respective proportion of wood fibers always varies depending on the tree species. In the case of conifers, this proportion is between around 90 and 95 percent, while deciduous trees have around 50 to 60 percent.
Although mechanical pulping requires a lot of energy, part of the process heat is recovered in the course of thermo-mechanical defibering.
This energy can then be used for drying the paper web in the paper machine. If the fiber material is to be additionally bleached, manufacturers usually use hydrogen peroxide and sodium dithionite for this purpose.

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FAQ

1. Question: What processes are used to produce the fiber products?
   Answer: Mechanical, semi-chemical and chemical processes are used for the production.

2. Question: Why is corrugated board popular as a packaging material?Answer: Corrugated board is popular because it is strong, sustainable and light at the same time.