Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1996-03-15
1997-12-09
Czaja, Donald E.
Paper making and fiber liberation
Processes and products
Non-fiber additive
162166, 1621681, 1621682, 162158, 106400, 106465, 106471, 106499, D21H 1756, D21H 1755, D21H 1754
Patent
active
056956100
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO ELATED APPLICATION
This application is a 35 U.S.C. 371 of PCT/EP94/03304 filed Oct. 6, 1994.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aqueous pigment slurries which contain up to 80% by weight of a finely divided pigment in dispersed form and from 0.1 to 5% by weight of at least one dispersant, and the use of the aqueous pigment slurries as an additive to the paper stock in the production of filler-containing paper.
2. Description of the Related Art
An efficient dispersant is required for the preparation of highly concentrated aqueous pigment slurries having a low viscosity. Known dispersants are, for example, low molecular weight polyacrylic acids. They can be prepared, for example, by the process disclosed in EP-B-0 002 771, by polymerization of acrylic acid in isopropanol at relatively high temperatures and pressures.
U.S. Pat. No. 3,945,843 furthermore discloses the use of copolymers of methyl acrylate and acrylic acid as dispersants for the preparation of highly concentrated pigment slurries, such as calcium carbonate slurries. The pigment slurries have solids contents of from 50 to 80% by weight and are used for coating paper. However, the concentrated aqueous pigment slurries described above cannot be used in the production of filler-containing papers because the low molecular weight polyacrylic acids contained in the pigment slurries greatly interfere with the efficiency of drainage aids, retention aids and sizes.
The prior German Application P 43 06 608.9 which has not been previously published discloses aqueous pigment slurries which contain up to 80% by weight of a finely divided pigment in dispersed form and from 0.1 to 5% by weight of a dispersant. The dispersants used are reaction products which are obtainable by reacting ethyleneimine, polyetheramines and mixtures of the stated compounds with or nitriles of monoethylenically unsaturated carboxylic acids, chlorocarboxylic acids and/or glycidyl compounds of the formula ##STR1## where X is --NH.sub.2, --OMe or --OR, halohydrin, glycidyl, aziridine or isocyanate unit or a halogen atom as a functional group, weight aqueous solution at 20.degree. C., have a viscosity of at least 100 mPa.s.
These pigment slurries are used as an additive to the paper stock in the production of filler-containing paper, an increase in the drainage rate and an increase in the retention being achieved in comparison with the dispersant-free pigment additives used to date in the paper stock.
DE-B-24 36 386 discloses the use of nitrogen-containing condensation products which are obtainable by reacting 15-500 alkyleneimine units with ethylene oxide units and has been reacted at the terminal OH groups with at least an equivalent amount of epichlorohydrin weight resins which are still water-soluble, as drainage accelerators and retention aids in papermaking. In the form of a 20-25% strength aqueous solution at 25.degree. C., the water-soluble resins have a viscosity of more than 300 mPa.s.
It is an object of the present invention to provide pigment slurries which contain dispersants which do not adversely affect the efficiency of retention aids, drainage aids and sizes in the production of filler-containing papers.
SUMMARY OF THE INVENTION
We have found that this object is achieved, according to the invention, by aqueous pigment slurries which contain up to 80% by weight of a finely divided pigment in dispersed form and 0.1-5% by weight of at least one dispersant, if they contain, as dispersants, polyalkylenepolyamines having a molecular weight of at least 300 or water-soluble reaction products which are obtainable by reacting polyamidoamines grafted with ethyleneimine and halohydrin, glycidyl, aziridine or isocyanate unit or a halogen atom as a functional group have a viscosity of at least 100 mPa.s. Such highly concentrated pigment slurries are used as an additive to the paper stock in the production of filler-containing paper.
DETAILED DESCRIPTION OF THE INVENTION
Suitable pigments are all pigments
REFERENCES:
patent: 3325346 (1967-06-01), Osborg
patent: 3418204 (1968-12-01), Goldstein et al.
patent: 3925095 (1975-12-01), Bockmann et al.
patent: 3998652 (1976-12-01), Aign et al.
patent: 5059248 (1991-10-01), Signorino et al.
patent: 5131951 (1992-07-01), Yoshida et al.
patent: 5158611 (1992-10-01), Ura et al.
patent: 5169441 (1992-12-01), Lauzon
Auhorn Werner
Linhart Friedrich
Lorencak Primoz
Monch Dietmar
Weiser Jurgen
BASF - Aktiengesellschaft
Czaja Donald E.
Fortuna Jos'e A.
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