Process for coagulation of aqueous polymer dispersions
A process is proposed for coagulation of an aqueous polymer dispersion, which comprises, during or after the coagulation, converting the dissolved coagulation salt into an insoluble form.
1. A process, with the aid of a coagulation salt, for coagulation of an aqueous polymer dispersion comprising a polymer, stabilized via one or more dispersing agents, which comprises, during or after the coagulation, converting the coagulation salt from a dissolved from to an insoluble form, wherein the water solubility of the insoluble form being less than 6% by weight, wherein the HCO 3 is selected as anion of the coagulation salt, and wherein together with the coagulation salt with HCO 3 as its anion which is converted from the dissolved form to the insoluble form, at least one further coagulation salt is used which remains in the dissolved form after the coagulation process.
2. The process according to claim 1 , wherein the coagulation salt with HCO 3 as its anion is converted into the insoluble salt form via exposure to heat or to electromagnetic radiation, or sound, or chemicals.
3. The process according to claim 1 , wherein the dispersing agents have a sterically or electrostatically stabilizing action.
4. The process according to claim 3 , wherein the dispersing agents have been selected from the group of anionic, cationic, nonionic, or amophoteric surfactants.
5. The process according to claim 4 , wherein the dispersing agent is an anionic surfactant or a mixture composed of anionic and nonionic surfactants.
6. The process according to claim 1 , wherein a cation of the coagulation salt is selected from the group IIa or IIIa of the Periodic Table of the Elements.
7. The process according to claim 6 , wherein the cation of the coagulation salt is selected from the group of alkaline earth elements.
8. The process according to claim 7 , wherein the cation is magnesium.
9. The process according to claim 7 , wherein the cation is calcium.
10. The process according to claim 1 , wherein the dissolved HCO 3 salt is converted to the corresponding insoluble carbonate salt via heating to from 60 to 130° C.
11. The process according to claim 1 , wherein the polymer in the polymer dispersion is formed from one or more monomers selected from the following group: butadiene, isoprene, alkyl acrylates, methacrylates, styrene and its derivatives, vinyl chloride, unsaturated fatty acids and their derivatives, acrylates, methacrylates, epoxides, amides, anhydrides, acrylonitrile, and methacrylonitrile.
12. The process according to claim 11 , wherein the polymer in the polymer dispersion comprises polybutyl acrylate or polybutadiene.
13. A process for preparation of molding compositions, which comprises, after partial to complete removal of water, mixing/processing, in a melt, the polymer dispersion coagulated according to claim 1 with a second or with a plurality of further polymer(s).
14. The process according to claim 13 , wherein the water content of the coagulated polymer dispersion is from 5 to 40% by weight.
15. The process according to claim 13 , wherein the second polymer comprises PSAN, PMMA, or PVC.
16. A molding composition obtained by the process according to claim 12 .
17. A molding, a semifinished product, a fiber, a foam, or a foil composed of the molding composition according to claim 16 .
18. The process according to claim 14 , wherein the water content of the coagulated polymer dispersion is from 10 to 40% by weight.