Pishgaman products
Test liner paper
Kraft liner is a paper which can be produced with 80% to 100% (virgin or first hand) pulp. If we produce paper which is made of 100% recyclable paper, it is called liner, and if it has two layers, it is called test liner. In Iran, when a slight percentage of high quality pulp is added to this type of paper, it is called pseudo kraft.I should be mentioned that the less virgin pulp is used in kraft paper, the closer will be quality of the product to test liner paper. Test liner paper is used in the production of corrugated sheet, and as per its quality it can be used both as the external and internal layer. The grammage of this type of paper ranges between 90 to 220 grams. The test liner paper which is used as the external layer of corrugated cartons has special technical specifications. For example, the external layer absorbs less water than the internal layer. The reason for less water absorption of the external layer is to support cartons from absorbing the environmental humid and to print on it better. The reason for the higher water absorption of the internal layer is to have better adhesion on fluting paper. Moreover, the test liner paper has proper surface resistivity for high quality printing.
White top paper
White top paper is a kraft or test liner the top of which is white and is used for the outer layer of cartons. The quality of printing on it is desirable. The grammage of this type of paper ranges from 110 to 150 grams. Between 20% and 25% of white recycled paper is used on the top surface, and between 80% and 75% of the pulp of recycled cartons is used on bottom surface. The production machinery of this paper has two headboxes which can produce white top paper. At present, a few domestic manufacturing factories produce white top paper, and the rest of the domestic requirements for this paper are met by imported white top paper.
Fluting paper
The corrugated layer of the corrugated cardboard is used between two layers of paper. The base weight of the fluting paper is ranged between 80 and 200 grams/ m2. The corrugated layer gives the necessary resistance to cartons. The most important properties of this paper are firmness and resistance against crushing and fracture. The properties related to mechanical strength, cracking and tear are not considered important. In many cases, the appearance of the paper can be ignored. One special feature about fluting paper is its mobility through convertible machine. The mobility here means the ability of the sheet to withstand tensions and stretches in corrugating procedure without cracking and breakage. Two factors of increasing the mobility of sheet are high elasticity and the lack of wood chips and fibers sticking together. These specifications are created by refining pulp well and less stretch in the process of drying sheet to improve the elasticity in fluting paper. The fluting paper should have higher water absorption than test liner paper because very low water absorption prevents the penetration of adhesive into the paper. Concerning the fluting paper in corrugated sheet act as a buffer in cartons and its corrugated structure should be capable to distribute the forces on all parts of the package; this type of paper should be able to withstand static and reversible resistance after applying environmental forces.
Liner paper
The type of paper shares some of the characteristics, such as resistance against humidity or inherent strength of fibers, with outer layer but does not need an appropriate filter for printing or coating with bleached fibers to bleach the surface for printing etc. Liner paper can be made of recycled fibers, but it should be in an acceptable rank in terms of health because the recycled fibers in contact with food products may have bad odors and unpleasant smell. The paper used in middle layers of five or seven layer cartons is of this type because they only play a binding and bulking role. Most domestic paper-making mills produce this type of paper in single layer for the purpose of carton making.
