Use of polymers as assistants in the drying of aqueous polymer dispersions
AssigneeBASF SE
InventorsJoachim Pakusch, Bernhard Schuler, Walter Machtle, Roland Baumstark
Life of this patent
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Abstract
Polymers composed of at least >80% by weight of monomers of the formula ##STR1## where R.sup.1, R.sup.2 and R.sup.3 are each C.sub.1 -C.sub.3 -alkyl, R.sup.4 is C.sub.1 -C.sub.5 -alkyl and X is 0 or NH, are used as assistants in the drying of aqueous polymer dispersions and, in the case of a weight average relative molecular weight of from 5000 to 35,000, additionally as protective colloid for the preparation of aqueous polymer dispersions by the free radical aqueous emulsion polymerization method.
Claims31
A process comprising drying an aqueous dispersion of a polymer II, wherein the aqueous dispersion of the polymer II contains, as added drying assistant, at least one polymer I which, in polymerized form, is composed of
- from .gtoreq.85 to 100% by weight of monomer units of at least one monomer of the formula I and/or salts thereof (monomer a) ##STR3## wherein R.sup.1, R.sup.2, and R.sup.3, independently of one another, are each
- H or C.sub.1 -C.sub.3 -alkyl,
- R.sup.4 is C.sub.1 -C.sub.5 -alkylene and
- X is O or NH, and
- from 0 to .ltoreq.15% by weight of monomer units of at least one monomer capable of free radical copolymerization (monomer b).
A process comprising adding a polymer I which, in polymerized form is composed of from .gtoreq.85 to 100% by weight of monomer units of at least one monomer of the formula I or salts thereof (monomer a) ##STR4## wherein R.sup.1, R.sup.2, and R.sup.3, independently of one another, are each ##STR5## and from 0 to .ltoreq.15% by weight of monomer units of at least one monomer capable of free radical copolymerization (monomer b), as a drying assostant, to an aqueous dispersion of a polymer II differing from polymer I.
A polymer powder containing at least one polymer I which, in polymerized form, is composed of
- from .gtoreq.85 to 100% by weight of monomer units of at least one monomer of the formula I or salts thereof (monomer a) ##STR6## where R.sup.1, R.sup.2, and R.sup.3, independently of one another, are each H
- or C.sub.1 -C.sub.3 alkyl,
- and R.sup.4 is C.sub.1 -C.sub.5 -alkylene and
- X is O or NH,
- and from 0 to .ltoreq.15% by weight of monomer units of at least one monomer capable of free radical copolymerization (monomer b), and at least one polymer II differing from the polymer I, with the proviso that polymer II is dispersible in an aqueous medium.
An aqueous polymer dispersion of a polymer II whose emulsifier content is .ltoreq.2% by weight and which contains, as added dispersant, at least one polymer I which, in polymerized form, is composed of
- from 85 to 100% by weight of monomer units of at least one monomer of the formula I or salts thereof (monomer a) ##STR7## where R.sup.1, R.sup.2 and R.sup.3, independently of one another, are each H
- or C.sub.1 -C.sub.3 -alkyl,
- R.sup.4 is C.sub.1 -C.sub.5 -alkylene and
- X is O or NH, and
- from 0 to .ltoreq.15% by weight of monomer units of at least one monomer capable of free radical copolymerization (monomer b), and has a relative average molecular weight of from 5000 to 35000, with the proviso that polymer II is dispersible in an aqueous medium.
A process for preparing polymer powders comprising adding a polymer I which, in polymerized form, is composed of
- from .gtoreq.85 to 100% by weight of monomer units of at least one monomer of the formula I or salts thereof (monomer a) ##STR8## where R.sup.1, R.sup.2 and R.sup.3, independently of one another, are each H
- or C.sub.1 -C.sub.3 -alkyl,
- R.sup.4 is C.sub.1 -C.sub.5 -alkylene and
- X is O or NH, and
- from 0 to .ltoreq.15% to 100% by weight of monomer units of at least one monomer capable of free radical copolymerization (monomer b), as a drying assistant, to an aqueous dispersion of a polymer II differing from polymer I, and drying said aqueous dispersion.
The process for the free radical aqueous emulsion polymerization of monomers having at least one ethylenically unsaturated group, wherein a polymer I which, in polymerized form, is composed of
- from .gtoreq.85 to 100% by weight of monomer units of at least one monomer of the formula I or salts thereof (monomer a) ##STR9## where R.sup.1, R.sup.2 and R.sup.3, independently of one another, are each H or C.sub.1 -C.sub.3 -alkyl,
- R.sup.4 is C.sub.1 -C.sub.5 -alkylene and
- X is O or NH, and
- from 0 to .ltoreq.15% by weight of at least one monomer capable of free radical copolymerization (monomer b), and whose relative weight average molecular weight is from 5000 to 35,000, is added before, during or after the end of the polymerization.
Dependencies are inferred from the claim text.