Reducing molecular weight distribution of polyether glycols by s

Details Reducing molecular weight distribution of polyether glycols by s Reducing molecular weight distribution of polyether glycols by s

1992-09-15

1994-04-12

Manoharan, Virginia

Distillation: processes, separatory

Plural distillations performed on same material

One a filming distillation

159 49, 203 80, 203 89, 203 91, 568617, 568621, B01D 122, B01D 310, C07C 4138

Patent

active

053022556

ABSTRACT:
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.

REFERENCES:
patent: 4568775 (1986-02-01), Aoshima et al.
patent: 4585592 (1986-04-01), Mueller
patent: 4686273 (1987-08-01), Harris
patent: 4762951 (1988-08-01), Mueller
patent: 4904745 (1990-02-01), Inoue et al.
patent: 4933503 (1990-06-01), Mueller
patent: 5053553 (1991-10-01), Dorai

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