Menetelmä retention säätämiseksi ja menetelmässä käytettävä välituote

摘要

The invention provides a method of controlling retention on a forming fabric in a paper making process, an intermediate product for use in the method, as well as use of material for the intermediate product. For making the intermediate product at least one paper making chemical is added to a slurry of fine cellulose fibres such as micro fibrillated cellulose (MFC), the specific surface area of those fibres being larger than that of the fibres of the main fibrous suspension for paper making, causing the paper making chemical being adsorbed on the fine cellulose fibres. This intermediate product is then incorporated in the main fibrous suspension before the suspension is supplied from the paper machine head box to the forming fabric. Other paper making chemicals may be added to the fibrous suspension before or after addition of the intermediate product, so that interactions between different chemicals are prevented. The invention permits an increased retention in general as well as improved control of retention of paper making chemicals separately and/or in relation to each other.