| 摘要 |
A method of making paper by depositing cellulose fibres as a layer from an aqueous suspension, and de-watering said layer of cellulose fibres, in which method, to improve the dry strength of the paper product, the cellulose fibres are treated successively with a cationic non-formaldehyde polymer and an anionic polymer which is an aminoplast resin whose repeating unit is anionic. The method can be employed to give paper of usefully improved dry strength, without generating an unacceptable level of free formaldehyde in the working environment. Treatment of the cellulose fibres is preferably carried out by successively adding the cationic polymer and the anionic polymer to the aqueous suspension from which the cellulose fibres are deposited.
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