Paper or board making machine for manufacturing high filler content paper or board and method

Abstract

The invention pertains to a paper or board making machine for manufacturing high filler content paper or board and to a corresponding method. The paper or board making machine comprises a forming section (101) in which at least one wire (105) arranged in a wire loop is provided for forming a web (W) from a fiber suspension, a closed draw press section (102) in which at least two press nips (N, N) being formed between two rolls (118, 119) each are provided for dewatering the web (W) transferred from the forming section (101), and a drying section (103) in which at least one drying cylinder (132) is provided for drying the web (W) transferred from the closed draw press section (102). The forming section (101) comprises a headbox (99) being capable of supplying liquids onto the wire (105, 109) in a layered manner and comprising a turbulence generator and a nozzle chamber having two converging walls (21, 22) forming a nozzle outlet (24). The turbulence generator has at least three diffusers (1, 3, 5, 7, 9) creating turbulence in liquids supplied into each respective diffuser (1, 3, 5, 7, 9) via feeding means (25, 27, 29) for feeding pulp suspension and/or water as the liquids. Each of the diffusers (1, 3, 5, 7, 9) has an outlet into the nozzle chamber. A central diffuser (1) of the at least three diffusers (1, 3, 5, 7, 9) has two blades (11, 13) arranged at its outlet and extending into the nozzle chamber in a converging manner. The blades (11, 13) separate a liquid flowing through the central diffuser (1) from liquids flowing through adjacent diffusers (3, 5, 7, 9). In the transporting direction of the web an impingement drying means (123, 124) is arranged before the at least one drying cylinder (132) in the drying section (103).

Description

technical field [0001] The invention relates to a paper or board machine and a corresponding method for producing paper or board with a high filler content. Background technique [0002] When making paper, the papermaker's goal is to use as much filler as possible in order to maintain the desired functional properties for the paper that is subsequently made. This is due to the fact that the price of the fiber is approximately six times higher than that of the filler (PCC). Filler GCC is even cheaper than PCC. However, the use of filler GCC leads to a decrease in the bulk of the paper. In addition to the loss of strength and bulk, higher filler contents generally limit the runnability of the paper machine. Also, the higher filler content makes the paper less strong when wet, so it is rather challenging when the web starts running in the dryer section. In addition, a certain minimum strength is required in the size press to allow the paper to withstand natural traction and...

AI Technical Summary

Problems solved by technology

However, the use of filler GCC will lead to a decrease in the bulk of the paper

In addition to the loss of strength and bulk, higher filler content usually limits the runnab

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