摘要:
A method for purifying polyether polyols made with double metal cyanide (DMC) catalysts is disclosed. A poly(oxypropylene) polyol containing DMC catalyst residues is combined with an amount of an alkali metal compound sufficient to convert DMC residues to an insoluble species, but not sufficient to generate polyol alkoxide groups. The polyol is heated in the presence of water, and is then filtered and stripped. The method eliminates the need to use magnesium silicate in removing DMC catalysts from polyols.
摘要:
A productive process for making conventional and low-unsaturation polyether polyols is disclosed. The process involves continuous removal of allyl alcohol and lower allyl alcohol propoxylates from the polyol during manufacture. The process can be performed at high temperatures and/or low catalyst concentrations. Polyether polyols with exceptionally low monol contents can be prepared.
摘要:
The concentration of propenyl ethers in a hydroxy-functional polyether having oxypropylene units is reduced by a process including the step of contacting the polyether with an acid ion exchange resin for a time and at a temperature sufficient for the conversion of at least some of the propenyl ethers to propionaldehyde and in the presence of sufficient water for the conversion. Optionally, the polyether is treated with an epoxy compound in an amount sufficient to reduce the acidity of the polyol.
摘要:
Polyether glycols, especially poly(tetramethylene ether) glycol (PTMEG) having a narrow molecular weight distribution of about 1.25 to 1.80, or dispersity of 1.05 to 1.90, are made by a process involving distilling the low molecular weight fraction in unit operations including at least one short-path distillation evaporator. Two short-path distillation evaporators, in series, are desirable if significant narrowing of the PTMEG is required. In these units, PTMEG is subjected to temperatures in the range of 270.degree.-400.degree. C. with the hold-up time varying between 10-200 seconds. The required vacuum to force the separation of the low molecular weight PTMEG varies between 0.001 mm and 1.0 mbar. PTMEG residue from the distillation unit is also characterized by its low water content and low concentration of oligomeric cyclic ethers.
摘要:
The present invention relates to a process for improving the polyurethane-forming reactivity of a propylene oxide-based ethylene oxide-free polyol produced using a double metal cyanide complex catalyst by incorporating therein a minor amount of a base prior to employing the polyol in a polyurethane-forming reaction. Also claimed is the base-containing polyol composition produced in accordance with the present invention.
摘要:
High purity polyether polyol compositions such as polyethylene glycol are made having small amounts of impurities such as oligomers of active hydrogen compounds with alkylene oxides. The high purity is achieved by subjecting the polyether polyol compositions to membrane filtration to get less than about 10 parts per million of the low molecular weight oligomers.
摘要:
A novel perfluoropolyether containing 0.1 to 10% by weight of halogen atoms as bonded in the molecule is obtained by reacting tetrafluoroethylene with oxygen in a fluorinated solvent or a chlorofluorinated solvent under ultraviolet irradiation in the presence of a halogenated hydrocarbon chain transfer agent having a chain transfer coefficient with respect to methyl methacrylate of at least 5.times.10.sup.-5.
摘要:
The process for the scission of high molecular weight perfluoropolyethers having neutral end groups obtained from photo-oxidation processes of perfluoroolefins, or fluorination of hydrogenated polyalkylene oxides, or by polymerization with opening of the partially fluorinated oxetane ring, the scission being carried out in the presence of catalysts selected from the group consisting of fluorides, oxyfluorides and oxides of transition metals, or selected from the group consisting of Al, Sn, and Sb, at temperatures ranging from 150.degree. to 380.degree. C. The scission process leads to the formation of low molecular weight perfluoropolyethers having neutral and acid end groups, the perfluoropolyetheral acids being subjected to conversion reactions in order to obtain functionalized perfluoropolyethers. The products can be used as operative fluids for high vacuum pumps.
摘要:
A process for the scission of high molecular weight perfluoropolyethers having neutral end groups obtained from photo-oxidation processes of perfluoroolefins, or fluorination of hydrogenated polyalkylene oxides, or by polymerization with opening of the partially fluorinated oxetane ring, said scission being carried out in the presence of catalysts composed of fluorides, oxyfluorides, or oxides of transition metals, or of Al, Sn, Sb, at temperatures ranging from 150.degree. to 380.degree. C.; said scission process leads to the formation of low molecular weight perfluoropolyethers having neutral and acid end groups, the perfluoropolyethereal acids being subjectable to conversion reactions in order to obtain functionalized perfluoropolyethers and to be utilized to provide new polymers.
摘要:
Strong fibers of poly(ethylene oxide) result from crystallization of the polymer of molecular weight of at least about 500,000 in a shear flow field. Using solutions of a polymer with a molecular weight greater than about 1,000,000, fibers with a tensile strength and tensile modulus of at least 0.1 and 0.5 GPa, respectively, can be readily obtained. Crystallization from a xylene solution within the range from about 35.degree. to about 45.degree. C. is particularly effective.