Sizing of paper
AssigneeCiba Specialty Chemicals Water Treatments Ltd.
InventorsPeter Peutherer, Ian Mark Waring, Lesley Collett
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Abstract
Sizing dispersions of liquid reactive size are made by dispersing the reactive size as a neat liquid into a dispersion of bentonite or other anionic microparticulate material in water. These dispersions can be used for internal sizing, for instance wherein the dispersion is used as the anionic microparticulate stage in a microparticulate retention paper-making process, or they can be used for external sizing.
Claims24
A process of making a sizing dispersion of a reactive anhydride size which is liquid at room temperature, the process comprising dispersing the reactive anhydride size as a neat liquid into a dispersion of anionic microparticulate material in water in which the anionic microparticulate material is selected from swelling clays, silica, polysilicic acid, polysilicate microgel and polyaluminosilicate microgel, using less than 2% surfactant based on the weight of the size.
A sizing dispersion comprising a dispersion in water of a reactive size which is liquid at room temperature and anionic microparticulate material selected from swelling clays, silica, polysilicic acid, polysilicate microgel and polyaluminosilicate microgel which stabilises the dispersion, and in which the dispersion is substantially free of cationic polyelectrolyte and is free of surfactant.
A process for making sized paper form a cellulosic suspension utilising a microparticulate retention system comprising a polymeric retention aid and a microparticluate anionic material selected from swelling clays, silica, polysilicic acid, polysilicate microgel and polyaluminosilicate microgel, the process comprising providing a cellulosic suspension containing the polymeric retention aid, then mixing into the suspension a dispersion which is in water and which contains the microparticulate anionic material and the water insoluble reactive size, draining the suspension to form a sheet and drying the sheet, characterised in that the dispersion contains the microparticulate material and the reactive size and is substantially free of additives selected from cationic polyelectrolytes and surfactants.
Dependencies are inferred from the claim text.