Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-03-20
2002-02-26
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S621000, C568S623000, C568S624000
Reexamination Certificate
active
06350920
ABSTRACT:
This application is a 371 of PCT/EP98/04860, filed Aug. 5, 1998.
The present invention relates to a process for the preparation of polyether polyols by reacting polyols with epoxides in the presence of basic catalysts, by removing the bases from the polyethers by means of OH-functional solid inorganic metal compounds, returning the base-laden compounds to the reaction of polyols with epoxides or treating the base-laden compounds with polyols and using those polyols in the reaction with epoxides.
From U.S. Pat. No. 3,528,920 it is known to remove basic catalysts used in the preparation of polyether polyols from the polyether polyols. In order to remove the basic catalysts, the polyether polyols were neutralised with sulfuric acid then treated with magnesium silicate, dried and subsequently distilled at elevated temperature in order to remove water. The magnesium silicate was then separated from the polymer product in a separate step.
U.S. Pat. No. 4,029,879 discloses an improved process for removing basic catalysts from polyether polyols by treating the polyether polyols with magnesium silicate in the presence of from 1 to 5 wt. % water. In a separate step, the adsorbent must then be separated from the polyether polyol by filtration and the water must be separated off by distillation.
Disadvantages of the above-mentioned processes are the large number of purification steps, the use of acids for neutralisation, and the formation of unrecoverable, economically and ecologically unsound, contaminated magnesium silicate waste. Owing to the known processes for removing catalysts from polyether polyols, which are associated with the described disadvantages, the processes used hitherto are not very economical.
The object of the present invention is to make available an economically and ecologically advantageous process for removing basic catalysts from polyether polyols, which avoids the disadvantages of the known processes.
The present invention provides a process for the preparation of polyether polyols by reacting polyols with epoxides in the presence of basic catalysts, which process is characterised in that the polyether polyols containing the basic catalysts are treated with OH-functional solid compounds of metals of groups III to VIII of the periodic system of the elements (Mendeleyev), the said compounds being insoluble in the polyether polyols and having BET surface areas of from 10 to 1000 m
2
/g, the solid inorganic compounds laden with the basic catalysts are isolated from the polyether polyol and used in the reaction of the polyols with epoxides, or the isolated inorganic compounds laden with the basic catalysts are brought into contact with the polyols that are to be used in the reaction with epoxides, those polyols are separated from the inorganic compounds and delivered to the reaction with the epoxides.
The preparation of polyether polyols has long been known and is described in general terms, for example, in Kunststoffhandbuch, Volume 7, Polyurethane, Carl Hanser Verlag, Munich-Vienna, 1973, p. 58 ff. All known polyols come into consideration as starter compounds for the epoxide polymerisation. Special mention may be made of mono-, di-, tri- and tetra-ethylene glycol, mono-, di-, tri- and tetrapolypropylene glycol, 1,2-, 1,3-, 1,4-butanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, hexanetriol, sugars, such as saccharose, fructose, maltose, sucrose, xylose, sorbitol, palatinitol, xylitol, oxyalkylation products of ammonia and amines, such as ethylenediamine, diethylenetriamine, piperazine, aniline, toluylenediamine, methylenedianiline, phenols such as hydroquinone, resorcinol, pyrocatechols, bisphenol F, bisphenol A and their oxyalkylation products, and also so-called prepolymers, which are obtained by reacting the above-mentioned polyols with from 0.5 to 4 mol, preferably from 0.7 to 2 mol, of epoxide/mol of polyol.
There are preferably used mono- to tetra-ethylene glycol, mono- to tetra-propylene glycol, glycerol, trimethylolpropane, pentaerythritol and the above-mentioned sugars and their hydrogenation products.
Suitable epoxides are ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide and mixtures of those epoxides. Ethylene oxide and propylene oxide are preferred.
There are used as basic catalysts especially potassium hydroxide and sodium hydroxide.
As mentioned above, the basic catalysts remain in the polyether polyols when the polyether polyols are prepared and must be removed therefrom.
By the process according to the invention it is now possible to remove the basic catalysts by treating the polyether polyols containing the basic catalysts with OH-functional solid compounds of metals of groups III to VIII of the periodic system of the elements, the said compounds being insoluble in the polyether polyols. There may be mentioned as OH-functional compounds of metals preferably the hydroxides and hydroxy oxides of aluminium, gallium, silicon, tin, titanium, zirconium, hafnium, tantalum, niobium and iron, especially the hydroxides and hydroxy oxides of aluminium, silicon, tin, titanium, zirconium, tantalum and niobium, very especially of aluminium, silicon, titanium, tantalum and niobium. Of course, the hydroxides and hydroxy oxides of the mentioned metals may also be used in the form of chemical compounds or in mixtures with one another. Mention may be made of, for example, aluminium-silicon hydroxy oxides and titanium-zirconium hydroxy oxides.
It is also possible to mix the mentioned hydroxides and hydroxy oxides with other metal compounds, such as magnesium silicates or aluminium titanates, as well as with layered silicates of the montmorillonite, bentonite and (hydro)talcite type. The amount of such admixed metal compounds is, depending on the procedure, up to 500 parts by weight, preferably 200 parts by weight, based on 1 part by weight of basic catalyst.
Very special preference is given to the use of the hydroxy oxides of the above-mentioned metals.
The amount of the above-mentioned solid inorganic compounds to be used is up to 1000 parts by weight, preferably up to 400 parts by weight, based on 1 part by weight of basic catalyst.
The adsorbents of the above-described type used in the process according to the invention for removing the basic catalysts are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Vol. A1, 557 ff; A27, 74 ff; A20, 190-271 and 297-311; A24, 12 ff; A26, 78 ff; A17, 255 ff; A23, 583-791.
The adsorbents used have a BET surface area of from 10 to 1000 m
2
/g, preferably from 20 to 900 m
2
/g, especially from 25 to 800 m
2
/g. They can be used as powders or in the form of course-ground material, granules, spheres, cylindrical bodies, hollow cylindrical bodies, or rings. The OH-functional surfaces of the mentioned hydroxides and hydroxy oxides are obtained especially by suitable methods of calcining precipitated hydroxy oxides of the mentioned metals or their gel-like hydrates at relatively low temperatures. The preparation of such surface-rich hydroxides and hydroxy oxides of the above-mentioned metals is known and is described, for example, in Kirk Othmer, Encyclopedia of Chemical Technology, 3rd edition, Vol. 2, p. 218 ff (1978); Ullmann's Encyclopedia of Industrial Chemistry under the metal names indicated above.
In the preparation of polyether polyols there are used as basic catalysts in addition to potassium and sodium hydroxide mentioned above also the hydroxides of the other alkali metals and those of the alkaline earth metals, although to a lesser degree. In addition, it is possible to use as basic catalysts tertiary amines, such as triethylamine, tributylamine, tetramethylethylenediamine, pentamethylenediethylenetriamine, diethylpiperazine, methyl-diaza-bicycloundecene, methyl-diaza-bicyclononene and pentamethylguanidine.
Implementation of the process according to the invention involves in principle the following operations:
reaction of the polyols with epoxides in the presence of basic catalysts to form polyether polyols,
treatme
Buysch Hans-Josef
Dietrich Manfred
Gupta Pramod
Ooms Pieter
Bayer Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Keys Rosalynd
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