Storage stable solutions of optical brighteners
AssigneeClariant Finance (BVI) Limited
InventorsJohn Martin Farrar, Andrew Clive Jackson, Margaret Mahon, Martin Oberholzer
Life of this patent
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Abstract
The instant invention relates to storage stable solutions of optical brighteners based on certain salt forms of anilino-substituted bistriazinyl derivatives of 4,4′-diaminostilbene-2,2′-disulphonic acid and of organic acids which do not need extra solubilizing additives.
Claims16
An aqueous solution consisting essentially of 15 to 35% by weight of a compound of formula (1)
- wherein
- R is hydrogen or a methyl radical,
- M+ is Li+, Na+, or K+,
- n is less than or equal to 1.5, and
- of 0.1 to 2.0% by weight of an organic acid selected from the group consisting of citric acid, glycolic acid, acetic acid and formic acid.
A process for preparing an aqueous solution, wherein the aqueous solution comprises 10 to 40% by weight of a compound of formula (1)
- wherein
- R is hydrogen or a methyl radical,
- M+ is Li+, Na+, or K+,
- n is less than or equal to 1.5, and of 0.05 to 5% by weight of an organic acid selected from the group consisting of citric acid, glycolic acid, acetic acid and formic acid, comprising the step of converting a compound of formula (2)
- wherein
- R is defined as above,
- in the form of an aqueous solution to a mixed salt form (1) in which at least 25% of the M+ ions associated with the sulphonate groups have been replaced by (CH3)2NH+CH2CH2OH ions, by treatment with 2-dimethylaminoethanol and an organic acid.
A process for whitening of paper comprising the steps of
- providing a pulp suspension,
- adding 0.01 to 2% by weight based on dry fibre of an aqueous solution
- wherein the aqueous solution consists essentially of 15 to 35% by weight of a compound of formula (1)
- wherein
- R is hydrogen or a methyl radical,
- M is Li+, Na+, or K+,
- n is less than or equal to 1.5, and
- 0.1 to 2% by weight of an organic acid selected from the group consisting of citric acid, glycolic acid, acetic acid and formic acid,
- producing a paper sheet from the pulp suspension,
- pressing and drying the paper sheet.
A process for whitening of paper comprising the steps of
- preparing an aqueous coating composition by mixing together chalk or other white pigments, one or more dispersing agents, a primary latex binder and optionally a secondary binder, and optionally other additives,
- adding 0.01 to 3% by weight based on dry pigment of an aqueous solution
- wherein the aqueous solution consists essentially of 15 to 35% by weight of a compound of formula (1)
- wherein
- R is hydrogen or a methyl radical,
- M+ is Li+, Na+, or K+,
- n is less than or equal to 1.5, and
- of 0.1 to 2% by weight of an organic acid selected from the group consisting of citric acid, glycolic acid, acetic acid and formic acid,
- applying the coating composition to a paper sheet to form a coated paper sheet, and
- drying the coated paper sheet.
Dependencies are inferred from the claim text.