Double metal cyanide catalysts for preparing poly-etherpolyols

Details Double metal cyanide catalysts for preparing poly-etherpolyols Double metal cyanide catalysts for preparing poly-etherpolyols

2000-02-10

2001-03-20

Wood, Elizabeth D. (Department: 1755)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From heterocyclic reactant containing as ring atoms oxygen,...

C502S152000, C502S153000, C502S154000, C502S155000, C502S156000, C502S159000, C502S175000, C502S200000, C549S512000, C549S513000, C549S518000, C549S539000, C568S617000, C568S622000, C568S623000, C568S624000

Reexamination Certificate

active

06204357

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to new double metal cyanide (DMC) catalysts, to a process for the preparation of these new double metal cyanide catalysts, to a process for the preparation of polyetherpolyols by the polyaddition of alkylene oxides to starter compounds which contain active hydrogen atoms in the presence of these new double metal cyanide catalysts, and to the polyetherpolyols produced by this process.
Double metal cyanide (DMC) catalysts for the polyaddition of alkylene oxides to starter compounds containing active hydrogen atoms are known and described in, for example, U.S. Pat. Nos. 3,404,109, 3,829,505, 3,941,849 and 5,158,922. The use of these DMC catalysts for preparing polyetherpolyols causes, in particular, a reduction in the proportion of monofunctional polyethers with terminal double bonds, i.e., the so-called monools, as compared with the conventional preparation of polyetherpolyols using conventional alkali metal catalysts such as, for example, alkali metal hydroxides. The polyetherpolyols obtained in this way may be processed to produce high quality polyurethanes (e.g., elastomers, foams, coatings).
DMC catalysts are, in general, usually obtained by reacting an aqueous solution of a metal salt with an aqueous solution of a metal cyanide salt in the presence of an organic complex ligand such as, for example, an ether. In a typical catalyst preparation, for example, aqueous solutions of zinc chloride (in excess) and potassium hexacyanocobaltate are mixed and then dimethoxyethane (glyme) is added to the suspension produced. After filtering and washing the catalyst with an aqueous glyme solution, an active catalyst of the general formula:
Zn
3
[Co(CN)
6
]
2
.x
ZnCl
2
.y
H
2
O.
z
glyme
is obtained (see, for example, EP-A 700 949).
Other DMC catalysts are disclosed in, for example, JP-A 4 145 123, U.S. Pat. No. 5,470,813, EP-A 700 949, EP-743 093, EP-A 761 708 and WO 97/40086, which are described as further reducing the proportion of monofunctional polyethers with terminal double bonds during the preparation of polyetherpolyols by using tertiary butanol as the organic complex ligand. Tertiary butanol can be used either alone, or combined with a polyether (see, for example, EP-A 700 949, EP-A 761 708, and WO 97/40086). In addition, the induction time during the polyaddition reaction of alkylene oxides with corresponding starter compounds is reduced and the catalyst activity is increased by the use of these DMC catalysts.
The object of the present invention was to provide improved DMC catalysts for the polyaddition of alkylene oxides to corresponding starter compounds which exhibit additionally increased catalytic activity as compared with the currently known catalyst types. This leads to improved economic viability of the method for the preparation of polyetherpolyols due to the shortened alkoxylation times. Ideally, as a result of this increased catalytic activity, the catalyst can then be used in such small concentrations (i.e., 25 ppm or less) that the costly procedure required to separate the catalyst from the product is no longer necessary and the resultant polyetherpolyol product can be used directly for polyurethane production.
Surprisingly, it has now been found that DMC catalysts which contain a cyclodextrin as an additional complex ligand exhibit greatly increased activity during the process for the production of polyetherpolyols.
SUMMARY OF THE INVENTION
The present invention provides a double metal cyanide (DMC) catalyst comprising:
a) one or more, preferably one, double metal cyanide compounds,
b) one or more, preferably one, organic complex ligands, and
c) one or more, preferably one, cyclodextrins, with the proviso that b) the organic complex ligand and c) the cyclodextrin are different compounds.
The double metal cyanide catalyst of the invention may additionally comprise d) water, preferably in an amount of from 1 to 10% by weight related to the total weight of the resultant DMC catalyst, and/or e) one or more water-soluble metal salts, preferably in an amount of from 5 to 25% by weight related to the total weight of the resultant DMC catalyst, which correspond to the formula (I):
M(X)
n
  (I)
from the preparation of the double metal cyanide compounds a). In formula (I) above,
M: represents one of the following metals Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sn(II), Pb(II), Fe(III), Mo(IV), Mo(VI), Al(III), V(V), V(IV), Sr(II), WV(IV), W(VI), Cu(II) and Cr(III), with Zn(II), Fe(II), Co(II) and Ni(II) being particularly preferred;
each X: represents an anion which may be the same or different (preferably the same), with the anions preferably being selected from the group consisting of halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and nitrates; and
n: represents 1, 2 or 3.
The double metal cyanide compounds a) contained in the catalysts according to the present invention comprise the reaction products of water-soluble metal salts and water-soluble metal cyanide salts.
To prepare a) the double metal cyanide compounds, it is preferred that component e), the water-soluble metal salts, correspond to the general formula (I):
M(X)
n
,  (I)
wherein:
M: represents a metal selected from the group consisting of Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sn(II), Pb(II), Fe(III), Mo(IV), Mo(VI), Al(III), V(V), V(IV), Sr(II), W(IV), W(VI), Cu(II) and Cr(III), and is more preferably a metal selected from the group consisting of Zn(II), Fe(II), Co(II) and Ni(II);
each X: represents an anion which may be the same or different (preferably all X's are the same), with X preferably being selected from the group of halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and nitrates; and
n: represents 1, 2 or 3.
Some examples of water-soluble metal salts suitable for the present invention include compounds such as zinc chloride, zinc bromide, zinc acetate, zinc acetylacetonate, zinc benzoate, zinc nitrate, iron(II) sulfate, iron(II) bromide, iron(II) chloride, cobalt(II) chloride, cobalt(II) thiocyanate, nickel(II) chloride and nickel(II) nitrate. Mixtures of different water-soluble metal salts may also be used in the present invention.
To prepare double metal cyanide compounds a), it is preferred that the water-soluble metal cyanide salts correspond to the general formula (II):
(Y)
a
M′(CN)
b
(A)
c
,  (II)
wherein:
M′: represents a metal selected from the group consisting of Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V), and is more preferably selected from the group consisting of Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II);
each Y: represents a cation and may be the same or different (preferably the same), with the cations being selected from the group consisting of the alkali metal ions and alkaline earth metal ions;
each A: represents an anion and may the same or different (preferably the same), with the anions being selected from the group consisting of halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and nitrates; and
the subscripts a, b and c: each represent an integer with the values being individually selected such that the metal cyanide salt is electrically neutral;
wherein:
a: preferably represents 1, 2, 3 or 4;
b: preferably represents 4, 5 or 6; and
c: preferably represents 0.
The water-soluble metal cyanide salts may contain one or more of the metals described as being suitable for M′ above including Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV), V(V), and various mixtures thereof.
Examples of some suitable compounds to be used as double metal cyanide salts in the present invention include compounds such as potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacya

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