Description

Kraft paper is made of 80 to 100% virgin pulp or recyclable pulp. If a paper is made of 100% recyclable pulp, it’s called Liner, and if it is double-layer, it is called Testliner. In Iran, when a small percentage of high-quality pulp is added to this kind of paper, it is called Pseudo-Kraft paper. Lining paper or Testliner paper is used in the production of corrugated cardboard, and considering its quality, it can be used as both outer and inner layers. Also, it can have a white top Testliner. This kind of paper weighs around 90 to 220 grams. Testliner paper, which is applied as the outer layer of flute cardboard, has specific technical characteristics. For instance, the outer layer has less water absorption than the inner layer, and that is because it supports cartons to avoid absorbing the environment humidity, and for better printing. The inner layer absorbs more water since it has better cohesion on flute paper. In addition, Testliner paper has proper surface resistance for high-quality printing. This product is made of recycled fibers, however, in terms of hygiene, it should be placed in an acceptable rank since recycled fibers in contact with food products may have an unpleasant aroma. Papers applied in the middle layers of cartons with quintuple or septuple layers are this kind since they only have protective and volume-making roles. Most domestic papermaking factories use this type of paper single-layer to produce cartons. Usages of Testliner paper in Flute cardboard Two layers of lining and one or several layers of the flute have been used to produce flute cardboard. The base weight of corrugated or flute paper is between 80 to 200 grams per square meter. This corrugated layer gives the required resistance to the cartons. Its resistance to crushing and breaking is one of the most important facets of this layer. The appearance of the layer can be ignored in most cases. One of the specific features of Flute paper is its ability to resist traction through corrugation without cracks and fractures. Two phenomenal factors for increasing its resistance are chips and wood fibers which are not clinging to each other, and high elasticity. These characteristics are made in Flute paper by well- refining of pulp and less tension in the process of sheet drying to improve its elasticity. Flute paper must tolerate more water absorption than Testliner paper since absorbing water prevents glue to penetrate the paper. The fluted or corrugated paper structure must be such as to distribute environmental forces in all parts of the package and tolerate them.