Double metal cyanide catalysts for producing polyether polyols

Details Double metal cyanide catalysts for producing polyether polyols Double metal cyanide catalysts for producing polyether polyols

2001-08-08

2003-07-01

Truong, Duc (Department: 1711)

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

Synthetic resins

From organic oxygen-containing reactant

C528S422000, C528S482000, C528S486000, C528S491000, C502S175000, C502S176000, C502S159000, C502S200000

Reexamination Certificate

active

06586566

ABSTRACT:

This invention relates to novel double metal cyanide (DMC) catalysts for the production of polyether polyols by polyaddition of alkylene oxides onto starter compounds having active hydrogen atoms.
Double metal cyanide (DMC) catalysts for the polyaddition of alkylene oxides onto starter compounds having active hydrogen atoms are known (c.f. for example U.S. Pat. Nos. 3,404,109, 3,829,505, 3,941,849 and 5,158,922). Using these DMC catalysts for the production of polyether polyols in particular brings about a reduction in the proportion of monofunctional polyethers with terminal double bonds, so-called monools, in comparison with the conventional production of polyether polyols by means of alkali metal catalysts, such as alkali metal hydroxides. The resultant polyether polyols may be further processed to yield high-grade polyurethanes (for example elastomers, foams, coatings). DMC catalysts are usually obtained by reacting an aqueous solution of a metal salt with the aqueous solution of a metal cyanide salt in the presence of an organic complex ligand, for example an ether. In one typical catalyst preparation method, aqueous solutions of zinc chloride (in excess) and potassium hexacyanocobaltate are, for example, mixed and dimethoxyethane (glyme) is then added to the resultant suspension. Once the catalyst has been filtered and washed with 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 (c.f. for example EP-A 700 949).
JP-A 4 145 123, U.S. Pat. No. 5,470,813, EP-A 700 949, EP-A 743 093, EP-A 761 708 and WO 97/40086 disclose DMC catalysts which, by using tert.-butanol as an organic complex ligand (alone or in combination with a polyether (EP-A 700 949, EP-A 761 708, WO 97/40086)), further reduce the proportion of monofunctional polyethers with terminal double bonds in the production of polyether polyols. Moreover, using these DMC catalysts also reduces the induction time in the polyaddition reaction of the alkylene oxides with appropriate starter compounds and increases catalyst activity.
The object of the present invention was to provide further improved DMC catalysts for the polyaddition of alkylene oxides onto appropriate starter compounds, which catalysts exhibit increased catalyst activity in comparison with hitherto known catalyst types. By shortening the alkoxylation times, this improves the economic viability of the polyether polyol production process. Ideally, by virtue of its increased activity, the catalyst may then be used in such low concentrations (25 ppm or below) that it is no longer necessary to perform the highly elaborate separation of the catalyst from the product and the product may be used directly for polyurethane production.
It has surprisingly now been found that DMC catalysts which contain an ionic surface- or interface-active compound as a complex ligand exhibit greatly increased activity in polyether polyol production.
The present invention accordingly provides a double metal cyanide (DMC) catalyst containing
a) one or more, preferably one, double metal cyanide compounds,
b) one or more, preferably one, complex ligands other than c), and
c) one or more, preferably one, ionic surface- or interface-active compounds.
The catalyst according to the invention may optionally contain d) water, preferably 1 to 10 wt. %, and/or e) one or more water-soluble metal salts, preferably 5 to 25 wt. %, of the formula (I) M(X)
n
originating from the production of the double metal cyanide compounds a). In the formula (I), M is selected from among the 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), W(IV), W(VI), Cu(II) and Cr(III). Zn(II), Fe(II), Co(II) and Ni(II) are particularly preferred. The anions X are identical or different, preferably identical, and preferably selected from the group comprising halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates or nitrates. The value for n is 1, 2 or 3.
The double metal cyanide compounds a) present in the catalysts according to the invention are the reaction products of water-soluble metal salts and water-soluble metal cyanide salts.
Water-soluble metal salts suitable for the production of double metal cyanide compounds a) preferably have the general formula (I) M(X)
n
, wherein M is selected from among the 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), W(IV), W(VI), Cu(II) and Cr(III). Zn(II), Fe(II), Co(II) and Ni(II) are particularly preferred. The anions X are identical or different, preferably identical, and preferably selected from the group comprising halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothio-cyanates, carboxylates, oxalates or nitrates. The value for n is 1, 2 or 3.
Examples of suitable water-soluble metal salts are 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 various water-soluble metal salts may also be used.
Water-soluble metal cyanide salts suitable for the production of double metal cyanide compounds a) preferably have the general formula (II), (Y)
a
M′(CN)
b
(A)
c
, wherein M′ is selected from among the metals 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). M′ is particularly preferably selected from among the metals Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II). The water-soluble metal cyanide salt may contain one or more of these metals. The cations Y are identical or different, preferably identical, and are selected from among the group comprising alkali metal ions and alkaline earth metal ions. The anions A are identical or different, preferably identical, and are selected from among the group of halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates or nitrates. Not only a, but also b and c are integers, wherein the values for a, b and c are selected such that electron-neutrality of the metal cyanide salt is ensured; a is preferably 1, 2, 3 or 4; b is preferably 4, 5 or 6; c preferably has the value 0. Examples of suitable water-soluble metal cyanide salts are potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithium hexacyanocobaltate(III).
Preferred double metal cyanide compounds a), which are present in the catalysts according to the invention, are compounds of the general formula (III)
M
x
[M′
x′
(CN)
y
]
z
,
in which
M is defined as in the formula (I) and
M′ as in the formula (II), and
x, x′, y and z are integers and selected such that electron-neutrality of the double metal cyanide compound is ensured.
Preferably
x=3, x′=1, y=6 and z=2,
M=Zn(II), Fe(II), Co(II) or Ni(II) and
M′=Co(III), Fe(III), Cr(III) or Ir(III).
Examples of suitable double metal cyanide compounds a) are zinc hexacyanocobaltate(III), zinc hexacyanoiridate(ll), zinc hexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III). Further examples of suitable double metal cyanide compounds may be found, for example, in U.S. Pat. No. 5,158,922. Zinc hexacyanocobaltate(III) is particularly preferably used.
The organic complex ligands b) present in the DMC catalysts according to the invention are known in principle and have been exhaustively described in the prior art (for example in U.S. Pat. Nos. 5,158,922, 3,404,109, 3,829,505, 3,941,849, EP-A 700 949, EP-A 761 708, JP-A 4 145 123, U.S. Pat. No. 5,470,813, EP-A 743 093 and WO 97/40086). Preferred organic complex ligands are water-soluble, organic compounds having heteroatoms, such as oxygen, nitrogen, phosphorus or su

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