Improvements in or relating to the production of surface-coated papers using brightening agents

摘要

The brightness of white surface-coated paper is enhanced by incorporating in the paper support or in one or more surface coatings thereof or in both an anionic fluorescent compound or compounds and polyvinylpyrrolidone or a copolymer of vinylpyrrolidone and vinyl acetate or both. The fluorescent compound may be an amino-stilbene of the general formula FORM:0967891/C4-C5/1 where Q and Q1 are each FORM:0967891/C4-C5/2 or R5-CO-, R3, R4 and R5 are each hydrogen, halogen, hydroxyl, amino or any of a wide variety of organic radicals linked directly or through O, N or S (examples given in the Specification) and may be the same or different from one another and R1 and R2 are each a water-solubilizin group, e.g. sulpho or carboxyl or a salt thereof, or if at least one of the groups R3, R4 and R5 is anionic may be hydrogen. The fluoroscent compound and the polymer may be incorporated separately or may first be reacted to form an addition compound which is then incorporated. In the former case they may be present in the same layer or in different layers of the coated paper, or paper, e.g. a photographic paper, having the polymer incorporated in it or in a coating layer, may be treated with a solution, e.g. a developing, stop or fixing bath, containing the fluorescent compound. Specifications 614,155, 884,736 and 967,892 are referred to.ALSO:The brightness of white surface-coated paper is enhanced by incorporating in the paper support or in one or more surface coatings thereof or in both an anionic fluorescent compound or compounds and polyvinylpyrrolidone or a copolymer of vinylpyrrolidone and vinyl acetate or both. The fluorescent compound may be an amino-stilbene of the general formula: FORM:0967891/D1-D2/1 where Q and Q1 are each FORM:0967891/D1-D2/2 or R5-CO-, R3, R4 and R5 are each hydrogen, halogen, hydroxyl, amino or any of a wide variety of organic radicals linked directly or through O, N or S, (examples given in the Specification) and may be the same or different from one another and R1 and R2 are each a water solubilizing group, e.g. sulpho or carboxyl or a salt thereof, or if at least one of the groups R3, R4 and R5 is anionic may be hydrogen. The fluorescent compound and the polymer, may be incorporated separately or may first be reacted to form an addition compound which is then incorporated. In the former case they may be present in the same layer or in different layers of the coated paper, or paper, e.g. a photographic paper, having the polymer incorporated in it or in a coating layer, may be treated with a solution, e.g. a developing, stop or fixing bath, containing the fluorescent compound. Specifications 614,155, 884,736 and 967,892 are referred to.