GB710331A - Anti-sticking cellulosic sheets or films, and process and sizing emulsions for theirmanufacture - Google Patents

Abstract

Films cast from aqueous alkaline cellulosic solutions have a size thereon comprising a colloidal inorganic water-insoluble solid material and a non-ionogenic self-emulsifying lubricious substance which emulsifies in hot water or aqueous media without the use of an alkali or an extraneous emulsifying agent and renders surfaces to which it is applied slippery. The colloidal inorganic material may be colloidal silica, kaolin, aluminium hydroxide, or titanium oxide. The lubricious substances are preferably the partial esters of polyhydric alcohols and of fatty acids containing at least 8 carbon atoms in the molecule, e.g. partial esters of sorbitol, mannitol, glycol, or glycerol with stearic, oleic, myristic, or lauric acids. Alternatively they may be condensates of such esters with ethylene oxide containing for example, 1-100 ethylene oxide units per molecule, e.g. sorbitol mono-, di-, tri- or tetra-stearate containing 6 ethylene oxide units or polyethylene glycol mono-stearates containing 10-50 ethylene oxide units, as well as condensates of glycerol monostearates with ethylene oxide containing 1-100 ethylene oxide units. In an example a sheet of purified regenerated cellulose in the gel condition which has been cast from viscose is passed through an aqueous bath containing 5 per cent. by weight of glycerol, 0.1 of colloidal silica and 0.1 of a glycerol mono-stearate, excess bath liquid is removed from the sheet by means of doctor blades and the sheet dried by passage over drier rolls. The bath is prepared by dissolving the glycerol in water, adding a 30 per cent. aqueous dispersion of colloidal silica stabilized by the addition of sodium hydroxide to a pH of about 10, and then adding a small proportion of a relatively concentrated aqueous solution of the ester. In a similar example the bath contained 0.5 per cent. of colloidal silica and 0.5 of a polyethylene glycol monostearate containing 50 ethylene oxide units per molecule. The films treated may have been cast from solutions of low-substituted cellulose ethers, esters, and ether-esters such as glycerol cellulose, methyl or ethyl cellulose, cellulose glycollic acid, and cellulose phthalic acid.ALSO:Films cast from aqueous alkaline cellulosic solutions have a size thereon comprising a colloidal inorganic water-insoluble solid material and a non-ionogenic self-emulsifying lubricious substance which emulsifies in hot water or aqueous media without the use of an alkali or an extraneous emulsifying agent and renders surfaces to which it is applied slippery. The colloidal inorganic material may be colloidal silica, kaolin, aluminium hydroxide, or titanium oxide. The lubricious substances are preferably the partial esters of polyhydric alcohols and of fatty acids containing at least 8 carbon atoms in the molecule, e.g. partial esters of sorbitol, mannitol, glycol, or glycerol with stearic, oleic, myristic, or lauric acids. Alternatively they may be condensates of such esters with ethylene oxide containing for example, 1-100 ethylene oxide units per molecule, e.g. sorbitol mono-, di-, tri-, or tetra-stearate containing 6 ethylene oxide units or polyethylene glycol mono-stearates containing 10-50 ethylene oxide units, as well as condensates of glycerol monostearates with ethylene oxide containing 1-100 ethylene oxide units. In an example a sheet of purified regenerated cellulose in the gel condition which has been cast from viscose is passed through an aqueous bath containing 5 per cent. by weight of glycerol, 0.1 of colloidal silica and 0.1 of a glycerol monostearate, excess bath liquid is removed from the sheet by means of doctor blades and the sheet dried by passage over drier rolls. The bath is prepared by dissolving the glycerol in water, adding a 30 per cent. aqueous dispersion of colloidal silica stabilized by the addition of sodium hydroxide to a pH of about 10, and then adding a small proportion of a relatively concentrated aqueous solution of the ester. In a similar example the bath contained 0.5 per cent. of colloidal silica and 0.5 of a polyethylene glycol monostearate containing 50 ethylene oxide units per molecule. The films treated may have been cast from solutions of low-substituted cellulose ethers, esters and ether-esters such as glycerol cellulose, methyl or ethyl cellulose, cellulose glycollic acid, and cellulose phthalic acid.