Alkanolammonium-containing triazinyl flavonate whiteners
View Patent ↗A process for whitening paper in a size press includes contacting a cellulose sheet with a size press liquor that contains a surface size and a particular whitener containing sulfonate groups and cations, M, wherein at least 10% of all cations M have the formula in which R 5 to R 7 , independently of one another, denote hydrogen, a C 1 -C 4 -alkyl radical or an optionally further substituted C 2 -C 4 -hydroxyalkyl radical, and R 8 denotes an optionally further substituted C 2 -C 4 -hydroxyalkyl radical. The process provides superior paper whitening compared to a corresponding process in which the whitener cations are all sodium or potassium ions.
1. A process for whitening paper in the size press, comprising contacting a cellulose sheet with a size press liquor, wherein the size press liquor consists essentially of
(a) a whitener of the formula Ia
in which
M denotes a mixture containing the cation of the formula II
and Na + or K + , and
at least 10 mol % of all cations M correspond to the formula II;
(b) water,
(c) surface size, and
(d) optionally, starch, carrier substances, salts, standardizing agents, and/or auxiliaries.
2. The process according to claim 1 , wherein the size press liquor contains whiteners which comprise more than 50% by weight of a whitener of the formula Ia.
3. The process according to claim 1 , and comprising the starch, wherein the starch is natural, derivatized, or degraded starch.
4. The process according to claim 3 , wherein the starch is oxidatively degraded starch.
5. The process according to claim 1 , wherein the size press liquor comprises the whitener of the formula Ia in an amount of less than 2.5% by weight.
6. The process according to claim 1 , wherein the size press liquor comprises the whitener of the formula Ia in an amount of 0.01 to 2.0% by weight.
7. The process according to claim 1 , wherein at least 20 mol % of all cations M correspond to the formula II.
8. The process according to claim 1 , wherein at least 50 mol % of all cations M correspond to the formula II.
9. The process according to claim 1 , wherein at least 80 mol % of all cations M correspond to the formula II.
10. The process according to claim 1 , wherein, in Formula Ia, the terminal sulfo groups are each in the para position relative to the aniline nitrogen atom,
50 to 100 mol % of all cations M correspond to the formula II;
and
wherein the size press liquor comprises the whitener of the formula Ia in an amount of 0.5 to 2.0% by weight.
11. A size press liquor consisting essentially of:
(a) a whitener of the formula Ia
in which
M denotes a mixture containing the cation of the formula II
and Na + or K + , and
at least 10 mol % of all cations M correspond to the formula II;
(b) water,
(c) surface size, and
(d) optionally, starch, carrier substances, salts, standardizing agents, and/or auxiliaries.