Many of us have to make daily contact with cardboard products. Their main difference is the material itself - cardboard varies in density, shade, size, price and surface roughness. One of the most common is coated cardboard.
What is coating?
The coating process is the application of a special coating on cardboard or paper, which gives them gloss and specific properties. The composition applied to the surface consists of plasticizing and adhesive elements and various pigments, in the role of which are kaolin or chalk. Coating is carried out in several ways: machine, cast and off-machine. The last two types require the use of special equipment, while the first can be carried out on conventional paper technology.
There is another type of coating - scraper. Such a method consists in spraying on the surface of a cardboard or paper an excess amount of coating, which is then smoothed using a long thin plate - a scraper.
Depending on the purpose, coated cardboard can be coated with several layers of the composition. A large number of layers gives the material shine, an attractive appearance, and its surface - a snow-white shade.
What is coated cardboard?
Coated cardboard, or chromed cardboard - a material on the surface of which a special coating is applied, consisting of glue, pigment and plasticizer. It can be of several types: design, packaging and printing.
Depending on the purpose for which the chromed cardboard is made, it may differ from the number of layers and the thickness of the coating, double or single side coating.
Characteristics of coated cardboard
The main properties of coated cardboard, which are paid attention to when buying it, are:
- Rigidity.
- Delamination, breaking and breaking strength.
- Absorbency.
- Weight, density, size.
- Resistance to bending, humidity, punching.
- The number of layers and the degree of whiteness of the surface.
The quality of the raw materials used in the production and the method of processing the layers directly affect the mechanical properties of the cardboard.
A layer of adhesives and dyes is applied to the surface of the cardboard using special coating equipment. The composition is sprayed both in one or in several layers. In multilayer coating, a maximum of three layers are applied to the front surface of the cardboard, and one layer to the back.
The thickness of the deposition of layers varies from 4 to 40 g / m 2 . Depending on the thickness of the coated layer, the printed characteristics of the cardboard change. Coated cardboard, whose density is 230-520 g / m 2 , can be used in various fields of human activity.
Coated cardboard is often indicated by terms such as triplex and duplex.
- Duplex is the most common type of cardboard. The number of coating layers does not exceed three; it is mainly used for packaging. Multilayer coating is carried out according to the classical scheme: one layer is applied to the back of the sheet, three or two to the front. The upper and lower layers are made from quality raw materials - bleached waste paper, pulp or wood pulp. The liner is made of low quality waste paper, pulp or wood pulp;
- Triplex is an expensive and high quality type of cardboard. The quality and composition of the liner material does not change. The front and back layers are double-coated, which is why their properties are very different from the characteristics of duplex.
Differences between coated and uncoated cardboard
The main difference of coated cardboard is the application of a special composition to its surface. White coated cardboard with a smooth surface is much better than uncoated analogues for a long time preserves the printed image, since it is mainly used for marking, text signs and logos of the trademark.
Coated cardboard is often used to produce products that cannot be made from ordinary cardboard for aesthetic reasons, since coated or varnished coatings can be applied to coated. The disadvantages of such cardboard include its high cost.
Classification of coated cardboard
Coated cardboard according to the European classification is divided into several categories: SBB, FBB and WLC.
The first category — SBB, or SBS — refers to cardboard made from bleached pulp and coated on one or both sides with a coated coating. The density of the product is from 185 to 390 g / m 2 .
The second type - FBB - is also referred to as chromosulfur. Its density is 170-850 g / m 2. It consists of three layers, the liner is made of wood pulp, the lower and upper layers are bleached chemical cellulose. Both sides of the cardboard are coated.
The third type is WLC. It is coated cardboard from waste paper with a small addition of wood pulp. The insert is made of cheap cardboard, and high quality waste paper is used to manufacture the lower and upper layers. Coating is carried out both on one and on both sides.
In the German classification, coated cardboard is divided into four categories: uncoated, duplex, triplex and cardboard made from primary fibers. The material manufacturer sets its own marking.
According to Russian standards, coated cardboard is marked with the letter “M” and some others, indicating additional properties. For example, INR - coated cardboard on an unbleached basis, MO - cover, a cover is made from it. Chalkboard of bleached pulp - M.
The advantages of coated cardboard
The main advantage of coated cardboard is its versatility. The distinctive features of chromed cardboard include glossy gloss, whiteness, high-quality composition, the ability to use varnishes. Coated colored cardboard for a long time maintains clarity, brightness and saturation of the shade. The quality of the materials used and the number of coating layers play an equally important role in maintaining color.
Chromo cardboard is used very widely, due to which its production is cost-effective and fully pays off, not to mention the fact that in some production areas it is simply irreplaceable.
Scope of application
Initially, cardboard was created and used as an environmentally friendly and safe, affordable, cheap and convenient container for packaging, storage and shipping of pharmaceutical, food, agricultural and light products, which protected it from various influences. Cardboard packaging over time has become widely used for advertising, marking and signage. Often a box of coated cardboard is made to produce high-quality packaging.
To create a high-quality coating, the upper layers of the front surface are completely coated. This type of cardboard is mainly used for varnishing, embossing and transferring images with bright colors. This includes not only packing tubes, boxes and boxes, but also children's goods - toys, sets, printed materials, booklets and covers.
High-quality cardboard is used in almost all industries, which make special demands on the smoothness and whiteness of the product surface. Coated cardboard is often used as a packaging for gift and food products.
Cardboard recycling
Coated cardboard is disposed of as normal. Waste paper recycling in the Russian Federation falls on those enterprises that have been working in this service for a long time. The capacities of such corporations allow each year to process about 50 thousand tons.