Patent ID: 8608905

Claim:
A method of producing a three-layer fiber product having a grammage of 25 to 60 g/m 2 , the method comprising fitting on both sides of a middle layer consisting of at least one fiber layer, a fiber layer which contains a filler and which forms a surface layer of the fiber product, characterized in that the layers are formed by using a multilayer forming process wherein slush of pulp is layered in the headbox of a paper machine in such a way that filler and additives are added to the pulp used in the surface layers of the three-layer product, after which the pulps are fed separated from each other to the headbox and then immediately combined before the lip of the headbox, where the jet of the pulp slush is directed to the wire, and the filler of the surface layers consists at least partially of cellulose or lignocellulose fibrils, on which light-scattering material particles are deposited, the maximum content of which is 85% of the total weight of the filler; the amount of said filler in the surface layers is 5-50% by weight of the fibers of the surface layer; the grammage of each surface layer is approximately 2-20 g/m 2 ; and the ratio of the total weight of the surface layers in relation to the weight of the middle layer is 35/65 to 65/35.