Abstract
Today, many mills are manufacturing wet-strength papers with melamine-or urea-formaldehyde resins. But, when a bleached pulp is used, the whiteness of paper is slightly lowered with acid colloid resin treatment (yellowing of paper), so we carried out many tests and we found that,
(1) Six kinds of organic or inorganic acid colloid resins were used and when a lactic or phosphoric acid colloid resins were used, no yellowing occured.
(2) The yellowing of paper caused by acid colloid resin treatment is prevented with use of chelating agents (polyphosphate, E.D.T.A., etc.)
