Corrugated cardboard – applications, varieties, classification

Use of corrugated cardboard

The main use of corrugated cardboard is consumer packaging.

Many industrial goods today are packaged in three- and five-ply corrugated boxes.

Among others:

  1. Foodstuffs;
  2. Glassware and glassware;
  3. Glassware and ceramics;
  4. Cosmetics and perfumes;
  5. Medical supplies;
  6. Sanitary ware;
  7. Building materials;
  8. Industrial equipment;
  9. Household appliances and furniture.

Corrugated cardboard boxes are used to pack household items when moving.

The material is used as a separator for fragile objects such as crystal, glass and mirrors.

Due to its cushioning properties corrugated packaging is an effective way to protect office and household equipment, household items, furniture, industrial equipment and auto parts during storage and transportation.

Varieties of Kraft cardboard

Types of Kraft liners include:

  1. K – cellulose lining.
  2. BW – bleached cellulose top coat.
  3. MK – indication white with small spots.
  4. T2 – with a small proportion of recycled fiber in the composition.
  5. T3, C – test liners made entirely of recycled material.
  6. OY – dough pads with flecks.
  7. WT – test pads made of coated waste paper.

The most popular with consumers are the long-fiber varieties made of Kraft pulp. They are environmentally safe because they decompose in record time. In addition, they can be recycled, which significantly reduces production costs and the cost of the final product.

Grade and profile

Corrugated cardboard is divided into two classes: first and second. In this article we will look at the features of the second class of three-layer corrugated cardboard, in particular the two grades: T22 and T23. Another article has a more complete comparison – click. The profiles of these grades are listed below: B – 3 mm, C – 4 mm, E – 2 mm. In addition, it should be noted that the corrugated board of profile E is a micro corrugated board.

Produced by

A sulfate (chemical) version is often added to natural pulp, wood components. There are different ratios of primary and secondary raw materials. Barrier properties and technical characteristics depend on this. To get the desired texture, aluminum sulfate (alumina), starch, honey are added.

We follow a two-stage manufacturing process.

1) Raw material preparation. The fiber suspension is created by pouring the pulp into the pulping equipment. This equipment pulverizes the pulp and mixes it with water (quantity: 1 to 10). It is then purified on various devices. To remove large foreign particles such as staples and glass, the slurry is passed through a sieve with a coarse mesh. It then passes through a turbo-separator and a vibrating screen, where films, plastics and tissue residues are sifted out. The composition is then pumped into the pulsators to achieve a homogeneous consistency. In the composition basin, additives are added to the thick mass. This ends the first step.

2) Finishing of the finished sheets. Thoroughly cleaned semi-finished product is pressed into a long strip of cardboard. Several operations are performed: dewatering, pressing, drying. High pressure is applied to smooth the surface. To increase the thickness, the strips are glued together with starch paste. Finally, the strip is cut into rolls or sheets of the desired size.

The finished panel undergoes quality control. Its thickness, ability to absorb liquid and weight are checked. In some categories, electrical insulation properties and resistance to deformation are checked.

Types and classification of corrugated board

The number of layers in the sheet structure affects the properties of the material. The layers of corrugated and smooth paper are considered.

Depending on the number of layers, corrugated cardboard is made of two, three, five or seven layers.

Double-layer

The material consists of one corrugated and one flat layer. Its peculiarity is the ease of rolling. It is rigid in all directions in which it is corrugated.

Double-layer cardboard is used for lightweight packaging and cushioning of glassware, light bulbs or fluorescent tubes and other fragile items.

Three-layered

The most common type of packaging material.

The three-layer cardboard structure has a corrugated sheet in the center and two flat sheets on the edges, which provides good stiffness when bending in all directions.

This material is used as packaging for many purposes:

  1. Food manufacturing;
  2. Pharmaceuticals and medicines;
  3. Operation and transportation companies;
  4. Delivery of goods in online stores.

Five Layer

It is used to make durable packaging for bulky goods such as furniture, appliances, spare parts and other bulky items.

Seven-ply

The least popular type of corrugated board, consisting of three corrugated layers and four flat sheets. It has high strength and stiffness. It is suitable for packing large-sized goods. It stacks well and is crush-resistant. It can withstand a load of up to 200 kg/m2.

Corrugated cardboard is the stiffer and stronger the more layers.

Corrugated cardboard is classified depending on its size:

  1. A – large, h = 4.0 – 4.9 mm; t = 8.0 – 9.5 mm;
  2. B – medium, h = 3.1 – 3.9 mm; t = 6.8 – 7.9 mm;
  3. C – small, h = 2.2 – 3.0 mm; t = 5.5 – 6.5 mm;
  4. E – micro, h = 1.1 – 1.8 mm; t = 3.0 – 3.5 mm.

This is largely due to the length and height of the inner corrugations of corrugated board.

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