Abstract: A method for the purification or recovery of lactide rich streams by the combination of a suspension-based melt crystallization process with a subsequent separation of the pure lactide crystals in a wash column is disclosed.

Abstract: The invention relates to a method for the purification or recovery of orthophosphoric acid rich streams by suspension-based melt crystallization. The orthophosphoric acid is crystallized as the hemi-hydrate form and subsequent separation of such crystals in a wash-column produce a high purity acid/water solution that has been depleted of most of the metals and impurities other than water, thereby separating an orthophosphoric acid rich feed liquor into an ultra-pure orthophosphoric acid hemi-hydrate and a mother liquor containing almost all impurities originally present in the feed. The orthophosphoric acid rich feed liquor typically contains no more than 15 wt % water and 1 wt % other impurities. Individual metal ion composition in the purified orthophosphoric acid product is in the range of 100 to 1000 ppb (parts per billion= 1/1000 ppm) of each metal ion. The metal ion composition of the resulting purified product is thus typically below the detection limit of typical analysis equipment.

Abstract: A method for the purification or recovery of lactide rich streams by the combination of a suspension-based melt crystallization process with a subsequent separation of the pure lactide crystals in a wash column is disclosed.

Abstract: The invention relates to a method for the purification or recovery of orthophosphoric acid rich streams by suspension-based melt crystallization. The orthophosphoric acid is crystallized as the hemi-hydrate form and subsequent separation of such crystals in a wash-column produce a high purity acid/water solution that has been depleted of most of the metals and impurities other than water, thereby separating an orthophosphoric acid rich feed liquor into an ultra-pure orthophosphoric acid hemi-hydrate and a mother liquor containing almost all impurities originally present in the feed. The orthophosphoric acid rich feed liquor typically contains no more than 15 wt % water and 1 wt % other impurities. Individual metal ion composition in the purified orthophosphoric acid product is in the range of 100 to 1000 ppb (parts per billion= 1/1000 ppm) of each metal ion. The metal ion composition of the resulting purified product is thus typically below the detection limit of typical analysis equipment.

Abstract: The invention relates to an apparatus for the purification of a substance from a solution, a suspension or a mixture of liquids by crystallization, preferably in a continuous manner. The apparatus comprises a first crystallizer (1c) comprising an input (1) for receiving a liquid comprising the substance and an output (4) for discharging a slurry of liquid and crystals. The apparatus comprises also a first separator (1s) connected to the output 4 of the first crystallizer (1c) having a product output (2), and being with a residue output (5) connected to an input of a second crystallizer (2c), and a second separator (2s) being with an input connected to an output (6) of the second crystallizer (2c), a crystal output (7) of the second separator (2s) being connected to an input of the first crystallizer (1c).

Abstract: The invention relates to a crystallization method for forming crystals of a substance in a solution, a suspension, or a mixture of liquids, in particular ice crystals from an aqueous solution or organic crystals from an organic melt. The method comprises the steps of crystallizing the solution to form a crystal slurry by means of cooling in a heat exchanger and feeding the crystal slurry from an outflow side of the heat exchanger to an inflow side of the heat exchanger via a recirculation duct and separating at least a part of the crystals from the liquid. A recirculation pump is included in the recirculation duct wherein the slurry is continuously supplied through the recirculation duct such that the crystals are homogeneously distributed in the duct and the heat exchanger and such that the under cooling at the outlet of the heat exchange is the equilibrium temperature Teq minus 0.5 to 0.9 times the meta-stable region &Dgr;Tmax.

Abstract: The present invention relates to finely dispersed, low-viscosity polymer polyols which are stabilized in a novel manner and which are characterized by a high content of polystyrene or polystyrene copolymers. This invention also relates to the preparation of such polymer polyols, and their use for the preparation of polyurethane materials.

Abstract: Stable, agglomerate-free, low-viscosity graft copolymer dispersions are prepared by the radical polymerization of 25 to 65% by weight of ethylenically unsaturated monomers in the presence of a base polyol, a macromer, a low-molecular weight regulator and, optionally, an organic solvent. The dispersions of this process are suitable as a polyol component for the production of polyurethane plastics by the isocyanate addition process.

Abstract: A process for the production of stable, agglomerate-free, low viscosity graft copolymer dispersions through radical polymerization of ethylenically unsaturated monomers in the presence of a base polyol, a macromer, an enol ether of a specific formula, and optionally, an organic solvent. These enol ethers correspond to the general formula:A=CH--O--Rwherein:A represents a di-valent residue of the formula ##STR1## R represents an aliphatic hydrocarbon radical having 1 to 18 carbon atoms, a cycloaliphatic hydrocarbon radical having 5 to 10 carbon atoms, or a substituted or unsubstituted benzyl radical;andR' represents a hydrogen atom or an aliphatic hydrocarbon radical having 1 to 8 carbon atoms.

Abstract: This invention relates to the preparation of 3- and/or 4-substituted pyrrolidine catalysts corresponding to formula (I) ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, X.sub.1, X.sub.2, and Y have the meanings described for formula (I) and to use of such catalysts in the polyisocyanate polyaddition process.

Abstract: The present invention relates to a process for preparing polyisocyanate polyaddition products by reacting(a) polyisocyanates with(b) relatively high molecular weight compounds containing at least two isocyanate-reactive hydrogen atoms and(c) chain-extending agents, in the presence of(d) N-(aminoalkyl)pyrrolidine catalysts corresponding to formula (I) ##STR1## in which R is a C.sub.2-12 alkylene group (optionally containing O or N atoms but not isocyanate-reactive groups) andR' is hydrogen or a C.sub.1-4 alkyl group,(e) optionally, other known catalysts, and(f) other known additives.

Abstract: The present invention relates to a process for preparing polyisocyanate polyaddition products by reacting (a) polyisocyanates with (b) relatively high molecular weight compounds containing at least two isocyanate-reactive hydrogen atoms and (c) chain-extending agents, in the presence of (d) N-(aminoalkyl)pyrrolidine catalysts corresponding to formula (I) in which R is a C2-12 alkylene group (optionally containing O or N atoms but not isocyanate-reactive groups) and R′ is hydrogen or a C1-4 alkyl group, (e) optionally, other known catalysts, and (f) other known additives.