Cardboard is made of pulp , mechanical pulp and waste paper produced material , among other things, in printing as a printing surface, in the packaging industry to protect packaged goods (packaging material) or as a container (box or carton ) and in the graphic arts and in arts and crafts as artistic material and as Design substrate is used. Essentially, this is paper with a greater thickness. Sometimes cardboard is also made with wood to reinforce the cardboard.
Cardboard is usually multi-layered, i.e. it consists of several layers of paper of different thicknesses and sometimes of different materials, which are pressed together (crumpled) without the use of glue. One side can be painted - especially with the folding box board. Glued cardboard boxes are also produced. The grammage of cardboard is between 150 and 600 g / m², so that the material extends into the area of both paper and cardboard .
The production of cardboard is similar to that of paper . High-quality cardboard (e.g. folding box cardboard) usually consists of at least three layers, with the outer layers being optimized for strength and the inner layers for volume. In the first step, pulp and waste paper are prepared for further processing. If not already delivered, the pulp is broken down into its fibers and ground into an aqueous pulp.
The waste paper is freed from foreign bodies and dirt and also grinded. This recycling material can only be added to a certain extent, as the original fiber becomes shorter with each reprocessing until it can no longer be properly consolidated with the other fibers and the end product does not have sufficient stability. After further processing, u. a. chemical deinking (decolorizing, de-inking), the recycling material is also mixed into an aqueous solution with water and additives and added to the pulp.
This pulp is then applied to a sieve-like endless conveyor belt of the cardboard machine. As a result, the fibers contained in the pulp align themselves with the direction of the sieve. This direction of movement is extremely important when the cardboard is later processed into folding boxes. The resulting paper webs are pressed together wet (couched).
In the board machine, this endless web runs through various rolling and drying cylinders ( calenders ). Just like in paper production, 95% of the chemicals used leave the system with the wastewater. The remaining 5% remain in the paper or cardboard. After the last phase of drying has been completed, a so-called "line" is applied to the continuous cardboard web so that the cardboard can be printed with labels and images. The bar ( coating color , coating) is usually white liquid which contains mostly limestone, fillers and binders, the composition and type of materials used may vary widely. The composite of raw cardboard and coating goes through a rolling and drying phase in the next, penultimate working step. Depending on the requirements, the cardboard box can also be smoothed on the "line" side using a chrome-plated calender. In the last step, the continuous cardboard web is cut into individual sheets and stacked.
In general, a variety of different grades are commercially available, which are classified according to their fiber types. To make them easier to differentiate, a generally applicable code has been established, which consists of the characteristics of the surface treatment, the substance input and a code number. Examples of box designations could be: GN1, GD, UN4.
When it comes to surface treatment, a distinction is made between:
- A cast-coated (special type of pigment-coated)
- G pigment-coated
- U uncoated
There are five different types of substance entry:
- Z chemically bleached virgin fibers
- N chemically unbleached virgin fibers
- C wood pulp
- T Recycled pulp with white, yellow or brown back
- D recycled cellulose with a gray back
The codes are to be used according to the table below:
|Code number||Back color (except for GD and UD)||Specific volume of GD and UD [cm³ / g]|
List of cardboard types
- Bristol board: a board made of three or more layers glued together; Top layers are made from wood-free materials; Inlay is generally wood-containing; has high flexural rigidity and can be creased and grooved;
- Chromoduplex cardboard: cardboard with a one-sided coating of about 12 g / m²; the pre- product is the duplex cardboard
- Chromo-replacement cardboard: Cardboard, smooth on one side, with a light, wood-containing insert and a wood-free top layer on one or both sides
- Chromo cardboard: Cardboard with a matt coating on one or both sides of about 18 g / m². The pre- product is the chromo replacement cardboard
- Chromolux : Cardboard made of wood-free material, coated on one or both sides with a high-gloss finish, particularly stable
- Duplex cardboard / duplex cardboard: multi-layer cardboard with a gray insert, gray back and a wood-free or only slightly wood-containing top layer
- Egg carton : cardboard in a hollow shape made from ground wood
- Felt cardboard : is used to insert soft materials, such as B. Wallets used
- Finnboard : acid-free, yellowish cardboard made from pulp wood. Mainly used in model making
- Beverage carton : see composite carton
- Gray board (also machine gray board): Gray board because the color is gray. It is mainly used for bookbinding, is between 0.5 and 4 mm thick and consists of waste paper and cellulose
- Half cardboard: cardboard with a basis weight between 130 and 170 g / m²
- Handboard : older name because this cardboard was removed by hand after winding the thin layer into a thicker cardboard
- Hard cardboard : Hard cardboard is a solid cardboard that is made by winding and compressing several moist fiber layers on a format roller and is particularly resistant to bending and very tough
- Wooden board : Cardboard with a large proportion of wood pulp
- Index card : for the production of index cards
- Cardboard : for the production of cardboard packaging
- Leather cardboard : brown cardboard made from at least 30% brown pulp. This makes it particularly tough and supple, e.g. B. for cardboard boxes and cases
- Manila cardboard : Formerly made from Manila hemp (waste such as ship ropes), wood-free and mostly natural-colored material with high lightfastness and very good mechanical strength. Mostly processed into packaging paper
- Multiplex cardboard / multiplex cardboard: Cardboard made of at least two layers that differ in terms of material composition, area-related mass or color
- Postcard board : machine-smooth, satin-finished or coated types of cardboard with 150 to 190 g / m² for hand and machine lettering
- Triplex / triplex : squeezed together from three different layers (gegautschter) carton. Mostly smooth on one side. He is z. B. used in cardboard production
- Composite cardboard: made of cardboard and other materials, for example metal and plastic foils; Frequent use in beverage cartons , where several top or intermediate layers of polyethylene (PE) and aluminum are applied to prevent the carton from soaking through or the product being filled with light and air.
Usage and Risks
Cardboard is mainly used in the packaging industry and is used to manufacture folding boxes and other packaging such as fine cardboard boxes , book covers, displays, paper cups, beverage cartons and other products. The Wiggle Side Chair is a piece of cardboard seating .
In 2009, hazardous mineral oil contents were detected in foods that came from cardboard packaging made from recycled fibers. The industry is therefore trying to reduce the transition from mineral oil to food, in particular through technological solutions such as barriers through plastic coatings or inner bags. The entry routes for mineral oil into food packaging are printing inks, which mainly enter the recycling cycle via newspapers and advertising brochures. The mineral oil mixtures evaporate and pass from the packaging into the food. The health risk assessment of the findings of mineral oil in food is difficult because there are no data on the toxicity of the substances found after ingestion through food. Mineral oil is a complex mixture of saturated hydrocarbons ( MOSH : mineral oil saturated hydrocarbons) and aromatic hydrocarbons ( MOAH ; mineral oil aromatic hydrocarbons), some of which can be carcinogenic and mutagenic.
- German standard DIN 19303 draft: Cardboard - terms, definitions and classification , Beuth, Berlin 2010
- Paper ABC. Association of German Paper VDP, Bonn 2005, .
- Joachim Elias Zender: Lexicon books, printing, paper . Haupt, Bern / Stuttgart / Vienna 2008, ISBN 978-3-258-07370-5 .
- only indicates the color, can be coated or uncoated
- half box . In: Joachim Elias Zender: Lexicon book printing paper . Haupt Verlag, Bern / Stuttgart / Vienna 2008, p. 125
- Recycled cardboard. IDW-Online, October 26, 2011