Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-10-18
2002-11-19
Barts, Samuel (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S618000, C568S619000, C536S120000
Reexamination Certificate
active
06482993
ABSTRACT:
This is the National phase Application of PCT/EP99/02397, field Apr. 8, 1999.
This invention relates to a process for the production of long-chain polyether polyols without working up.
Polyether polyols are obtainable by polyaddition of alkylene oxides, such as for example ethylene oxide, propylene oxide, butylene oxide, onto compounds containing active hydrogen atoms, such as alcohols, amines, acid amides, phenols, and are used inter alia for the production of polyurethane plastics, surfactants and lubricants. Polyaddition of epoxides onto starter compounds is conventionally performed industrially by alkali metal catalysis. The predominantly used alkali metal catalysts are alkali metal hydroxides. Disadvantages of alkali metal hydroxide catalysed polyether polyol production are primarily the elaborate working up of the product due to neutralisation of the alkaline polymer (c.f. for example U.S. Pat. No. 3,715,402, U.S. Pat. No. 4,430,490, U.S. Pat. No. 4,507,475 and U.S. Pat. No. 4,137,398) and the base-catalysed rearrangement of epoxides, for example propylene oxide, which proceeds as a secondary reaction, to yield allyl or propenyl alcohols, which give rise to monofunctional polyethers having a terminal double bond, which are known as monools.
One method known for the reduction of the monool content in the polyether polyols is to use double metal cyanide (DMC) complex compounds as catalysts for the polyaddition of epoxides onto starter compounds (c.f. for example U.S. Pat. No. 3,404,109, U.S. Pat. No. 3,829,505, U.S. Pat. No. 3,941,849 and U.S. Pat. No. 5,158,922). The polyether polyols obtained in this manner may be processed to yield high grade polyurethanes (for example elastomers, foams, coatings).
EP 700 949, EP 761 708, WO 97/40086 and DE-A 197 45 120.9, 197 57 574.9 and 198 102 269.0 disclose improved DMC catalysts which allow a further reduction in the fraction of monofunctional polyethers having terminal double bonds in the production of polyether polyols. The improved DMC catalysts are extraordinarily highly active and allow the production of polyether polyols at such low catalyst usage rates (25 ppm or below) that it is no longer necessary to separate the catalyst from the polyol (c.f. for example page 5, lines 24-29 in EP 700 949).
One disadvantage of using DMC catalysts for the production of polyether polyols is that these catalysts usually require an induction period. Unlike alkali metal catalysts, DMC catalysts do not start epoxide polymerisation immediately once the epoxide and starter compound have been added to the catalyst. The DMC catalyst must first be activated by a small quantity of epoxide. Induction periods are typically of a duration of some minutes to several hours.
Another disadvantage is that conventional, low molecular weight starter compounds for alkali metal catalysed polyether polyol synthesis, such as for example propylene glycol, glycerol or trimethylolpropane, cannot be alkoxylated with DMC catalysts. DMC catalysts thus require the use of oligomeric, alkoxylated starter compounds (for example a propoxylated propylene glycol or glycerol) having molecular weights of above 200, which have previously been obtained from the above-stated low molecular weight starters by, for example, conventional alkali metal catalysis (for example KOH catalysis) and subsequent elaborate working up by neutralisation, filtration and dehydration. Problematically, even very small residual quantities of alkali metal catalyst in the alkoxylated starter compounds can deactivate the DMC catalyst, such that a further additional, time-consuming working up stage (for example treatment with an ion exchanger or adsorbent) is necessary in order to ensure complete removal of the alkali metal catalyst from the alkoxylated starter compound.
The object of the present invention is accordingly to provide a process for production of long-chain polyether polyols without working up, in which oligomeric, alkoxylated starter compounds are first obtained from the low molecular weight starter compound (for example propylene glycol or trimethylolpropane) by an alternative catalysis to the conventional alkali metal catalysis, which oligomeric, alkoxylated starter compounds may then directly, i.e. without working up or removal of the catalyst, be further extended to yield long-chain polyether polyols by means of highly active DMC catalysts at very low catalyst usage rates (30 ppm or below).
German patent application No. 197 02 787.3 describes a process for the production of polyether polyols by catalysis with perfluoroalkyl-sulfonic acid salts (perfluoroalkyl-sulfonates) of the metals of group III A of the periodic system of elements (in accordance with the TUPAC convention of 1970).
It has surprisingly now been found that oligomeric, alkoxylated starter compounds having molecular weights of between 200 and 1000, which have been obtained by the metal perfluoroalkylsulfonate catalysts described in the above-stated German patent application from conventional, low molecular weight starters, such as for example propylene glycol or trimethylolpropane, by reaction with alkylene oxides at reaction temperatures of 80 to 200° C. and catalyst concentrations of 5 to 200 ppm, relative to the quantity of the oligomeric, alkoxylated starter compound to be produced, may be converted directly, i.e. without working up and removal of the catalyst, by means of highly active DMC catalysts at very low catalyst usage rates (30 ppm or below) by reaction with alkylene oxides into higher molecular weight, long-chain polyether polyols. It this manner, long-chain polyether polyols may be produced entirely without working up.
It was also found that when the alkoxylated starter compounds obtained by catalysis with the metal perfluoroalkylsulfonates are used, the induction and alkoxylation times on DMC catalysis are distinctly reduced in comparison with the use of corresponding oligomeric starter compounds, which were produced by alkali metal catalysis and conventional working up.
By shortening the cycle times in polyether polyol production, reduced induction and alkoxylation times also improve the economic viability of the process.
The present invention accordingly provides a process for the production of long-chain polyether polyols without working up, in which oligomeric, alkoxylated starter compounds having molecular weights of 200 to 1000 are first obtained by catalysis with perfluoroalkylsulfonates of the metals of group III A of the periodic system of elements (in accordance with the IUPAC convention of 1970) from low molecular weight starters by reaction with alkylene oxides at reaction temperatures of 80 to 200° C. and catalyst concentrations of 5 to 200 ppm, which oligomeric, alkoxylated starter compounds are then converted without working up and removal of the catalyst by means of highly active DMC catalysts at a catalyst concentration of 30 ppm or below, relative to the quantity of polyether polyol to be produced, by reaction with alkylene oxides into higher molecular weight, long-chain polyether polyols.
Catalysts used according to the invention for the production of the oligomeric, alkoxylated starter compounds are perfluoroalkylsulfonates of the metals of group III A of the periodic system of elements (in accordance with the TUPAC convention of 1970). This comprises the metals scandium, yttrium and the rare earth metals lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. A further metal which may be used is “mixed metal” (also known as “didymium”), a mixture of rare earth metals obtained from ore.
Perfluoroalkylsulfonates are taken to be metal salts of perfluoroalkylsufonic acids, in which the metal is at least attached to a perfluoroalkylsulfonate group. Other suitable anions may also be present. Preferred compounds, are the metal salts of trifluoromethanesulfonic acid, which are known as trifluoromethanesulfonates or triflates. The following are preferably used: scandium, yttrium, lanthanum, ceri
Gupta Pramod
Hofmann Jörg
Barts Samuel
Bayer Aktiengesellschaft
Gil Joseph C.
Henry Michael C.
Sloane Carolyn M.
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