Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1990-12-04
1993-11-16
Chin, Peter
Paper making and fiber liberation
Processes and products
Non-fiber additive
1621683, 162175, D21H 1745
Patent
active
052620085
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the production of paper, board and cardboard by draining a paper stock in the presence of copolymers containing N-vinylformamide units.
JP-A-118 406/86 discloses water-soluble polyvinylamines which are prepared by polymerizing N-vinylformamide or mixtures of N-vinylformamide with other water-soluble monomers, such as acrylamide, N,N-dialkylacrylamides or diallyldialkylammonium salts and subsequently hydrolyzing the polymers with bases, e.g. ethylamine, diethylamine, ethylenediamine or morpholine. The polyvinylamines are used as drainage aids and retention aids in papermaking and as flocculants for wastewaters.
U.S. Pat. No. 4,421,602 discloses polymers which are obtainable by partial hydrolysis of polyl-N-vinylformamide with acids or bases. As a result of the hydrolysis, these polymers contain vinylamine and N-vinylformamide units. They are used, for example in papermaking, as drainage aids, flocculants and retention aids.
EP-A-0 220 603 discloses, inter alia, that N-vinylformamide can be subjected to copolymerization together with basic acrylates, such as dimethylaminoethyl acrylate, or N-vinylimidazolines, in supercritical carbon dioxide. The resulting finely divided copolymers are used in the partially hydrolyzed form, in which they contain vinylamine units, for example as retention aids and flocculants in papermaking.
EP-A-0 282 761 discloses a process for the production of paper, board and cardboard having high dry strength, in which the dry strength agent used is a mixture of cationic polymers, which may also contain, among typical monomers, polymerized units of vinylamine, and natural potato starch, the potato starch being converted into a water-soluble form by heating in an aqueous medium in the presence of a cationic polymer to temperatures above the gelatinization temperature of natural potato starch in the absence of oxidizing agents, polymerization initiators and alkali.
It is an object of the present invention to provide papermaking assistants which ideally are more effective than the conventional ones and which are technically more readily available.
We have found that this object is achieved, according to the invention, by a process for the production of paper, board and cardboard by draining a paper stock in the presence of a polymer containing N-vinylformamide units, if a nonhydrolyzed copolymer which contains, as polymerized units,
(a) from 99 to 1 mol % of N-vinylformamide and
(b) from 1 to 99 mol % of one or more water-soluble basic monomers of the formula ##STR2## where R.sup.1 is H, CH.sub.3 or C.sub.2 H.sub.5, R.sup.2, R.sup.3 and R.sup.4 are each H, CH.sub.3, C.sub.2 H.sub.5 or (--CH.sub.2 --CH.sub.2 --O--).sub.n H, R.sup.5 and R.sup.6 are each C.sub.1 -C.sub.10 -alkyl, A is C.sub.1 -C.sub.6 -alkylene, n is from 1 to 6 and Y.sup..crclbar. is an anion, is used in an amount of from 0.01 to 3.5% by weight, based on dry paper stock, as the polymer containing N-vinylformamide units.
The advantage of the nonhydrolyzed copolymers containing N-vinylformamide units over the previously used hydrolyzed copolymers which contain vinylamine units after the hydrolysis is that the hydrolysis, which is difficult to carry out in many cases, is dispensed with and effective papermaking assistants are obtainable by direct copolymerization.
A suitable monomer (a) of the copolymers is N-vinylformamide. This monomer is present in the copolymers in an amount of from 1 to 99, preferably from 60 to 95, mol %.
Suitable monomers of group (b) are the compounds of the formula I, of which the following compounds may be stated by way of example:
N-Trimethyl-N-(methacrylamidopropyl)-ammonium chloride is preferred.
Other suitable monomers of group (b) are the compounds of the formula II. Examples of compounds of this type are diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldiethylammonium chloride and diallyldiethylammonium bromide. Diallyldimethylammonium chloride is preferably used. The anion Y.sup..crclbar. is an acid radical and is preferabl
REFERENCES:
patent: 3597314 (1971-08-01), Laube et al.
patent: 4772359 (1988-09-01), Linhart et al.
patent: 4818341 (1989-04-01), Degen et al.
Freudenberg Enrique
Hartmann Heinrich
Moench Dietmar
Stange Andreas
BASF - Aktiengesellschaft
Chin Peter
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