Patent GB-1109537-A (GB)
Title: Optical brightening of paper
IPC: D21H21/30
Filed: 1966-12-09
Abstract: A composition suitable for use in the optical brightening of paper comprises a bis-s-triazinylaminostilbene - 2,21 - disulphonic acid having the formula <FORM:1109537/C3/1> in which the Ar groups are the same and are unsubstituted phenyl radicals or phenyl radicals substituted by halogen atoms, carboxylic or sulphonic acid groups or alkyl or alkoxy groups containing 1-5 carbon atoms, or a water-soluble salt thereof, e.g. an alkali or alkaline earth metal, ammonium or alkanolamine salt, together with degraded starch or a polymer or copolymer of butadiene-styrene, or acrylic or methacrylic acid together with degraded starch and/or casein.  The composition may be a starch size containing 0.2-2 g. of the brightening agent and 50-100 g. of degraded starch per litre and a wetting agent, e.g. an unsulphated or sulphated alkanol glycol ether in which the alkyl radical contains 8-14 carbon atoms and containing 1-20 ethylenoxy groups, or a pigment coating containing 0.2-5 g. of brightening agent and 350-650 g. of white pigment, e.g. china clay, CaSO4.10H2O, BaSO4, titanium dioxide, CaCO3 and mixtures thereof, per litre, and 8-30% by weight of binder comprising butadiene-styrene, acrylic or methacrylic acid polymers or copolymer together with degraded starch and/or casein, 0.2-0.6% by weight of a metal binding agent, e.g. a polyphosphate or polymetaphosphate, and 0.1-0.3% by weight of a wetting agent, e.g. an unsulphated or sulphated higher alkanol-polyglycol ether, calculated on the amount of white pigment used.  The compositions are preferably adjusted to an alkaline pH by the addition of ammonium hydroxide or sodium or potassium hydroxide, carbamate, borate, perborate or a mixture thereof.ALSO:Pulp and paper surfaces are brightened by applying thereto a bis-s-triazinylaminostilbene-2, 2\sv-disulphonic acid having the formula:  <FORM:1109537/D1-D2/1> in which the Ar groups are the same and are unsubstituted phenyl radicals or phenyl radicals, substituted by halogen atoms, carboxylic or sulphonic acid groups, or alkyl or alkoxy groups containing 1-5 carbon atoms, or a water-soluble salt thereof, e.g. an alkali or alkaline earth metal, ammonium or alkanolamine salt.  The brightening agent may be added to a starch size or pigment coating for the paper.  The starch size may contain 0.2-2g of the brightening agent and 50 - 100g of degraded starch per litre and a wetting agent, e.g. an unsulphated or sulphated alkanol glycol ether in which the alkyl radical contains 8-14 carbon atoms and containing 1-20 ethylenoxy groups, and the pigment coating may contain 0.2-5g of brightening agent and 350 - 650g of white pigment per litre and 8 - 30% by weight of binder, 0.2-0.6% by weight of metal binding agent and 0.1-0.3% by weight of a wetting agent calculated on the amount of white pigment used.  Suitable pigments are china clay, CaSO4.10H2O, BaSO4, titanium dioxide, CaCO3 and mixtures thereof.  Suitable binders are butadiene-styrene, acrylic or methacrylic acid polymers or copolymers, together with degraded starch and/or casein, suitable metal binding agents are polyphosphates or polymeta phosphates and suitable wetting agents are unsulphated or sulphated higher alkanol-polyglycol ethers.  The treating compositions are preferably adjusted to an alkaline pH by the addition of ammonium hydroxide or sodium or potassium hydroxide, carbonate, borate, perborate or a mixture thereof.