Versatile, flexible, fast and of high quality - Palamo is your guide when it comes to individual packaging solutions. And not only that: at Palamo, sustainability comes first.

Environmentally friendly materials, energy-efficient and resource-saving manufacturing processes, and a high recycling rate determine our everyday life. The focus here is particularly on methods such as the deinking process with integrated flotation.

In the following article, we will show you the importance of deinking and explain the procedure. If you are concerned about environmental compatibility, sustainability and recyclable packaging, you cannot avoid the deinking process.

You can find exciting information and interesting facts about sustainable packaging in our blog.

Deinking and floating - what is behind these terms?

The word deinking is the term used in English for ink removal.

The process: The respective (waste) papers are often glued or stapled together. Before they can be recycled, foreign bodies of this kind must be completely removed before the recycling process. And that's not all: printing ink and inks must also be completely removed from the waste paper. The so-called deinking process is used for this purpose.

In paper recycling, deinking is an important core or key process for achieving a high degree of whiteness. Printing ink and colors are removed with the aid of flotation. This is a physical-chemical separation process for solids with a fine-grained consistency. As part of the deinking process, floating is considered the most important process step in the recycling of paper in Europe.

The waste paper is freed from foreign bodies, shredded and mixed with water before the chemical substances are added in several steps. These wash the ink out of the paper fibers so that it collects on the surface of the water, where it is removed.

The deinking process and the floating process are therefore particularly suitable for recycling printed products whose inks are water-repellent. This requirement is met in particular by paper that has been printed using the offset printing process.

Printed matter with special finishes (for example varnish), flexographic inks, liquid toner prints, UV inks and also many digital prints can only be processed poorly or not at all with the deinking process.

The deinking method only works if water-repellent inks are used!

The deinking process has this historical origin

The historical roots of the deinking process go back to the 18th century and are closely associated with the name of Justus Claproth (1728 - 1805). Actually, his name stands for private draft laws, which strongly influenced the development of criminal law at the beginning of the 19th century.

Claproth did not devote himself to handicrafts, and in particular to craft processes, until 1754, when he was appointed a manufactory judge. In the process, he became aware of the shortage of rags for paper production.

At that time, rags made of cotton, linen or hemp, mixed with rope-making and spinning waste, formed the only available fiber raw material for the production of paper. In 1774, Claproth finally published the paper "An Invention to Make New Paper from Printed Paper Again, and to Wash Out the Printing Ink Completely.

In it, he documented various attempts to produce new writing paper from printed waste paper. He was assisted by the papermaker Johann Engelhard Schmid (1736-1811), in whose mill in Klein Lengden the trials were carried out.

Justus Claproth develops the first deinking process through trials

After only a few trials, they succeeded in producing a completely new material for paper production. According to the records, a process with four operations was established:

1. The bookbinding glue was removed with the help of hot water.
2. The waste paper was then processed for about twelve hours in the tamping mill with the addition of washing earth.
3. Then the waste paper was stored for eight days with the addition of lime.
4. Finally, the waste paper was ground in the paper Dutchman (Dutchman windmill) for about two hours before it was used again as new material for papermaking.
   
   

Deinking becomes the standard industrial process in the 1950s

This decolorization process, discovered and developed by Claproth, was a world first at the time. Nevertheless, this process did not attract much attention at first.

Most papermakers continued to focus on production by rag or used fibers from old clothing and later wood pulp as the base material for recycled paper. It was not until centuries later that the process now known as deinking caught on and finally established itself in industrial ink removal in the 1950s.

Through the interaction with flotation(physical-chemical separation process for fine-grained solids), it was thus possible to achieve a degree of whiteness not previously possible around 70 years ago. From then on, this allowed the production of sanitary and newsprint papers from recycled waste paper.

In detail: This is how the deinking process works

As an established process for ink removal, the complete deinking process always comprises several process steps. These traditionally include sorting, disintegration and flotation.

In the course of further developments and process improvements, thickening, hot dispersion and fine screening were gradually integrated as separate process steps. Only then is it possible to remove stickies from the paper in addition to ink and printing ink.

Modern deinking processes today also rely on a second flotation and thickening stage, as well as additional cleaning of the recycled water. This has a positive effect on the quality of the recycled paper produced. In the following, we have listed the individual process steps with detailed explanations for a better understanding.

1. The sort
   Before the actual de-inking process starts, the de-inking agent used for this purpose is Waste paper sorted. This is necessary because some Paper types from several different Paper fibers exist. Suitable for deinking are primarily Magazines- and Newsprint, corrugated board, cardboard or even before recycled paper.

   Sorting in this case also prevents the subsequent mixing of higher-quality and lower-quality papers. This is important because the starting material also determines the quality of the resulting recycled paper. After sorting, the paper is pressed and then delivered in bales to a paper mill for further processing.

2. Foreign body removal
   There, the paper bales are untangled again and transported in lanes via conveyor belt to a large Stirring vat (also referred to as a pulper). Large foreign bodies can be removed by hand as well as by a machine be removed directly on the conveyor belt.

   For example, a magnet is used here for removing staples or metal bands, or a so-called raker for removing cords, strapping and similar foreign objects.

   It is important that the pressure-sensitive adhesive used for the binding is always removed at the same time as the backing. This keeps the pressure-sensitive adhesive tape intact. This means that no particles containing adhesive get into the material to be recycled.

3. The operations in the pulper
   Several operations then run simultaneously in the stirred tank. Accordingly multifunctional then also presents itself the installed Mechanics. Two variants have become established. Pulpers with a perforated drum or pulpers with a trough plus integrated rotor. Basically, the often expensive Drum pulper better results in the form of a higher degree of whiteness.

   With the help of these two mechanisms, the recovered paper can be continuously and reliably shredded. However, this is only part of the performance in the third process step. In the stirred tank itself, the water and paper pieces are mixed to form a mixture with a pulpy consistency. Before this, the water is additionally enriched with various chemicals. These are intended to specifically support the detachment of the printing ink from the paper fibers and the decomposition of the waste paper.

4. Flotation
   Only when a waste paper pulp has been produced in the third step does the actual flotation begin. In order to achieve this special Separation process for fine-grained solids, paper manufacturers use certain substances or chemicals.
   The already at the Waste paper defibering chemicals introduced into the drum or pulper in several process steps form the basis here. Deinking or flotation recipes usually consist of four to five components.
   
   

   • Caustic soda: Alkaline solutions of sodium hydroxide(NaOH) are called caustic soda. Sodium hydroxide dissolves very well in water under strong heat formation. Depending on the mixing ratio of water and NaOH, the lye has a pH value between 8 and 14. In terms of consistency, NaOH lye is an aqueous, colorless substance. Caustic soda is usually obtained from a sodium chloride solution, which is also aqueous. This form of extraction is known as chlor-alkali electrolysis. In the deinking process, caustic soda has the task of decomposing the printing ink and impurities.

   • Hydrogen peroxide (H2O2): This is a largely stable liquid compound that acts as a very powerful oxidizing agent. This makes hydrogen peroxide an excellent bleaching and disinfecting agent at the same time.

     In floating, hydrogen peroxide therefore also takes on the function of a bleaching agent. In addition to the bleaching effect, it also counteracts the yellowing of fibers, for example. This often occurs with waste paper that is particularly heavy in wood. The substance also supports the detachment of printing inks.

   • Water glass: This substance belongs to the"glassy compounds". Available are water-soluble sodium, lithium and potassium silicates. These are available either as an aqueous solution or as a solid.

     Water glass is produced from finely ground glass, which is melted at temperatures up to a maximum of around 1500 °C. The glass is then used to make the glass. Various chemicals are then added. The chemicals used then ultimately determine which compound is produced.

     Sodium silicate is used for the deinking process. This compound is considered the best peroxide stabilizer. This is important in floating, as peroxide is very quickly decomposed by heavy metals (pulpers in this case). In addition, water glass also supports the detachment of printing inks as well as ink removal.

   • Surfactants: If the printing ink detaches from the fiber, particles of printing ink are formed. Washing-active substances are used to bind these particles. In this case, they are mostly anionic surfactants (soaps).
     In addition, the surfactants ensure adhesion to the air bubbles and improve the release of the printing inks.

     
     It is important to note that surfactants require hard water for deinking. If the water is too soft, the manufacturers alternatively use synthetic surfactants or Calcium ionswhich are added to the water. You can remove the surfactants afterwards with Flotation Foam.
     
     

   • Complexing agents: A few years ago, manufacturers also relied on complexing agents to bind detached color particles and reduce water hardness.

     Various complexing agents are used, for example, in the washing and cleaning industry and in deinking or floating as builders to mask water hardness. In the meantime, however, these so-called Lewis bases are hardly ever used in the deinking process.
     
     

5. The further procedure
   Immediately after floating, the waste paper pulp is then washed and bleached by hydrogen peroxide or oxygen. Often, this is followed by a second floatation pass as well as washing and bleaching again. Finally, virgin fibers are added to the recy cled paper pulp.
   
   This is to improve the stability of the recycled paper. The pulp is then smoothed and processed into webs before the drying process starts. As soon as the paper webs have finished drying, they are usually rolled up.
   During further processing, the paper webs are turned into various types of paper for printed products or even sanitary papers.
   
   

In addition, the following can be produced from old cardboard also recycled corrugated board or recycled cardboard cardboard. However, separate processing is necessary for this.