Abstract: The invention relates to a process for the manufacture of hydrophobic paper or board by using rosin sizing, an organic complexing agent being used together with the rosin size. The invention also relates to a sizing composition.

Abstract: A process for the delignification of a chemical pulp, such as a sulfate or sulfite pulp, in which process the pulp is treated with a peroxide and/or a peracid in the presence of an activating Ti-, V- or Cr-group transition metal, such as molybdenum, vanadium or tungsten. A compound containing at least one heteroatom, such as Si, P or B, which is capable of forming a heteropolyacid with the activating transition metal, is added to the pulp. The feeding of the activating transition metal and the heteroatom into the pulp may take place in one and the same alkaline solution, for example introduced into the solution or in the form of a compound of the silicomolybdenic acid type, formed in the solution. The peroxide and/or peracid treatment may constitute part of the bleaching sequence, which contains as potential other treatment steps, for example, a treatment with oxygen and a chelation for the removal of heavy metals such as iron, manganese and/or copper.

Abstract: A product contains silicon dioxide in the form of polysilicic acid in a supporting structure of cellulose. The polysilicic acid contains aluminum silicate sites. In the preparation of the product the cellulose and the silicon dioxide in the form of polysilicic acid are blended to obtain the product in solid form. The obtained blended product is modified with a compound containing aluminum, such as a solution aluminate, which causes the formation of aluminum silicate sites on the polysilicic acid. The cellulose used is viscose cellulose.