M-real Oyj

Metsa Board Oyj

Seppo Katajamäki

Esa Hassinen

Tom Nickull

The invention relates to cardboard used in authenticity products, comprising a fiber matrix having two surfaces, whereby the second surface of the fiber layer has a layer of surface sizing containing a marking agent in a particle form, its particle size being smaller than 50 &#x3bc;m. By incorporating the marking agent into the surface sizing, the particles of the marking agent can be attached to the board, at the same time decreasing their total consumption by 80 to 90% compared with a case where they would be added to pulp. By using particles of a size less than 50 &#x3bc;m, a top free from streaks and roughness can be formed, which streaks might otherwise weaken the quality of the product.

Cardboard and a method of manufacture thereof

A method of manufacturing a multilayer fibrous product. The product comprises at least two overlapping layers, each of which has a different fiber composition, and in the production of the product, chemical short stock is used at least partly. In the method, short stock is brought to a screening stage where fines, which pass a screen having an average hole size of 0.2-1.5 mm, are separated from it, in order to prepare at least two fiber fractions having different fiber compositions, and the fractions generated are recovered and included in different layers of the same fibrous product. With the invention, it is possible to screen an initial material and form a product which has better properties than a corresponding product, the initial material pulp of which has only been refined.

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Tampere, Finland

Seppo Katajamäki