Method for the preparation of ultra-pure bisphenol A and the use thereof

• US 5,696,295 A
• Filed: 04/06/1995
• Issued: 12/09/1997
• Est. Priority Date: 04/18/1994
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Quaeyhaegens, Frank, van Osselaer, Tony, Vaes, Johan, Meurer, Kurt-Peter, Hinz, Jurgen, Hallenberger, Kaspar, Wulff, Claus, Steude, Heinrich, Hooftman, Ignace
• Primary Examiner(s): Dees, Jose G.
• Assistant Examiner(s): Williams, Rosalynd
• Application Number:
  US08/418,583
• Time in Patent Office: 978 Days
• Field of Search: 568/722, 568/724, 568/723
• US Class Current: 568/724
• CPC Class Codes: C07C 37/74 by distillation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes
• CPC Class Codes: C08G 64/06 not containing aliphatic unsaturation

Abstract

The invention relates to a method for the purification by distillation of p,p-bisphenol A from the melt.

The p,p-bisphenol A melt thus obtained is highly heat-stable, stable in storage and colour-stable, is free from high-boiling components and no longer contains any surface-active or non-distillable metal, salt, acid or polymer components and no sulphur-containing components; o,p-BPA and phenol are removed and the low-boiling components are scarcely detectable.

Claims

1. A method for the preparation of ultra-pure bisphenol A by distillation, wherein:

a) a bisphenol A melt is distilled;

b) the distillation of the melt is carried out without the addition of stabilizers and under inert conditions;

c) the distillation is carried out such that the losses through decomposition of p,p-bisphenol A are less than 0.5%;

d) the distillation is carried out at temperatures of from 220°

C. to 250°

C.;

e) the distillation is carried out under vacuum at 1 to 50 mbar;

f) the distillation takes place in a first stage and a second stage,

g) wherein in the first stage

g.1) high-boiling components are removed;

g.2) metal dust, metal ions and traces of salt, traces of acid, polymeric and oligomeric residues of catalysts and other non-distillable higher molecular compounds are removed;

g.3) surface-active compounds are removed;

g.4) low-boiling components and sulphur-containing low-boiling components are removed or reduced;

g.5) concentrated BPA melt solutions containing low-boiling components, phenol and high-boiling components and having a p,p-bisphenol A content of greater than 92% are returned to the process as recycled streams;

h) not more than 5% of concentrated BPA melt solutions containing low-boiling components and not more than 10% of concentrated BPA melt solutions containing high-boiling components are channelled into the process;

i) low-boiling and high-boiling components contained in the channelled products mixed with p,p-BPA are returned to the process from the recycled streams, rearranged and partially recovered; and

j) distilled p,p-bisphenol A is worked up as a stable bottom product free of other substances.

2. The method of claim 1, wherein the bisphenol melt (a) is produced by melting flakes, powder or pellets of bisphenol A having a p,p-bisphenol A content of at least 90% and a phenol content less than 10%.