Double metal cyanide catalysts containing cyclic, bidentate complexing agents

Double metal cyanide (DMC) catalysts and methods for making them are disclosed. The catalysts comprise a DMC compound, an organic complexing agent, and optionally, a functionalized polymer. The key component is the complexing agent, which comprises a C.sub.3 -C.sub.5 aliphatic alcohol a cyclic, bidentate compound selected from lactams and lactones. Polyether polyols made from the catalysts contain reduced levels of high-molecular-weight (Mn greater than 400,000) components and consistently perform better in urethane applications such as flexible and molded foams.

FIELD OF THE INVENTION 
The invention relates to double metal cyanide (DMC) catalysts and methods 
for making them. In particular, the invention relates to DMC catalysts 
useful for making polyether polyols that contain reduced levels of a 
high-molecular-weight component compared with polyols made using other 
known DMC catalysts. 
BACKGROUND OF THE INVENTION 
Double metal cyanide complexes are well-known catalysts for epoxide 
polymerization. These active catalysts give polyether polyols that have 
low unsaturation compared with similar polyols made using basic (KOH) 
catalysis. The catalysts can be used to make many polymer products, 
including polyether, polyester, and polyetherester polyols. These polyols 
are useful in polyurethane coatings, elastomers, sealants, foams, and 
adhesives. 
DMC catalysts are usually made by reacting aqueous solutions of metal salts 
and metal cyanide salts to form a precipitate of the DMC compound. A 
water-soluble, low-molecular-weight organic complexing agent, typically an 
ether or an alcohol, is included in the catalyst preparation. The organic 
complexing agent is needed for favorable catalyst activity. Preparation of 
typical DMC catalysts is described, for example, in U.S. Pat. Nos. 
3,427,256, 3,289,505, and 5,158,922. 
While water-soluble ethers (e.g., dimethoxyethane ("glyme") or diglyme) and 
alcohols (e.g., isopropyl alcohol or tert-butyl alcohol) are most commonly 
used as the organic complexing agent, many other general classes of 
compounds have been described. For example, U.S. Pat. No. 4,477,589 
teaches (column 3, lines 20-22) that the organic complexing agent can be 
"an alcohol, aldehyde, ketone, ether, ester, amide, nitrile, or sulphide." 
Others list the same classes (see, e.g., U.S. Pat. No. 3,278,458 at column 
6 and U.S. Pat. No. 3,941,849 at column 13). According to U.S. Pat. No. 
3,278,458, the organic complexing agent preferably has "a substantially 
straight chain" or is "free of bulky groups." U.S. Pat. Nos. 5,158,922 
(column 6) and 5,470,813 (column 5) add nitriles and ureas to the list of 
suitable complexing agents. Japanese Pat. Appl. Kokai No. H3-128930 
(Morimoto et al.) teaches to use N,N-dialkylamides (e.g., 
N,N-dimethylacetamide) as the organic complexing agent to make catalysts 
with improved activity. 
For decades, DMC catalysts having a relatively high degree of crystallinity 
were used for making epoxide polymers. The most popular catalyst contained 
an organic complexing agent (usually glyme), water, excess metal salt 
(typically zinc chloride), and the DMC compound. Activity for epoxide 
polymerization, which exceeded the activity available from the commerical 
standard (KOH), was thought to be adequate. Later, it was appreciated that 
more active catalysts would be valuable for successful commercialization 
of polyols from DMC catalysts. 
Recent improvements in DMC catalyst technology have provided catalysts with 
exceptional activity for epoxide polymerization. For example, U.S. Pat. 
No. 5,470,813 describes substantially amorphous or non-crystalline 
catalysts that have much higher activities compared with earlier DMC 
catalysts. Other highly active DMC catalysts include, in addition to a low 
molecular weight organic complexing agent, a functionalized polymer such 
as a polyether (see U.S. Pat. Nos. 5,482,908 and 5,545,601) or other 
functional group-containing polymer (U.S. Pat. No. 5,714,428). Highly 
active DMC catalysts are generally substantially non-crystalline, as is 
evidenced by powder X-ray diffraction patterns that lack many sharp lines. 
The catalysts are active enough to allow their use at very low 
concentrations, often low enough to overcome any need to remove the 
catalyst from the polyol. 
Even the best DMC catalysts known could be improved. High catalyst activity 
has sometimes come at a price, namely the unexpected formation of traces 
of polyether having extremely high (greater than 400,000 or &gt;400K) number 
average molecular weight (Mn). This high-molecular-weight component, even 
at part-per-million levels, can negatively impact the way polyether 
polyols made from the catalysts perform in urethane applications such as 
flexible or molded polyurethane foams. For example, polyols that contain 
too much high-molecular-weight component can process poorly, give tight 
foams, or cause foam settling or collapse. While various approaches have 
been proposed for dealing with the high-molecular-weight component (e.g., 
reformulation of the urethane, removal of the component from the rest of 
the polyol after formation), an ideal strategy would begin with the 
catalyst and minimize or eliminate formation of the component. 
In sum, improved DMC catalysts are still needed. A preferred catalyst would 
have high activity similar to that of the substantially non-crystalline 
DMC catalysts now known (e.g., from U.S. Pat. Nos. 5,470,813 or 
5,482,908). A preferred catalyst would still give polyol products with low 
viscosities and low unsaturation. Ideally, however, the catalyst would not 
produce significant amounts of high-molecular-weight polyol components, 
particularly those having number average molecular weights greater than 
about 400,000. 
SUMMARY OF THE INVENTION 
The invention provides a way to make polyether polyols that perform more 
consistently in urethane applications. The invention is a double metal 
cyanide (DMC) catalyst and a method for making it. The catalyst comprises 
a DMC compound, an organic complexing agent, and optionally, from about 2 
to about 80 wt. % of a functionalized polymer. The key component is the 
organic complexing agent. It comprises a C.sub.3 -C.sub.5 aliphatic 
alcohol and from about 5 to about 95 mole percent, based on the total 
amount of organic complexing agent, of a cyclic, bidentate compound 
selected from lactams and lactones. The invention also includes a process 
for making an epoxide polymer using the catalysts. 
We surprisingly found that making DMC catalysts with a complexing agent 
comprising a mixture of a C.sub.3 -C.sub.5 aliphatic alcohol and a cyclic, 
bidentate compound selected from lactams and lactones offers valuable and 
unexpected benefits. In particular, polyether polyols made from the 
catalysts contain reduced levels of high-molecular-weight (Mn greater than 
400,000) components. This reduction makes the polyols process better in 
urethane applications such as flexible and molded foams. 
DETAILED DESCRIPTION OF THE INVENTION 
Catalysts of the invention comprise a double metal cyanide (DMC) compound, 
an organic complexing agent mixture, and optionally, a functionalized 
polymer. 
Double metal cyanide compounds useful in the invention are the reaction 
products of a water-soluble metal salt and a water-soluble metal cyanide 
salt. The water-soluble metal salt preferably has the general formula 
M(X).sub.n in which M is 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). More 
preferably, M is selected from the group consisting of Zn(II), Fe(II), 
Co(II), and Ni(II). In the formula, X is preferably an anion selected from 
the group consisting of halide, hydroxide, sulfate, carbonate, cyanide, 
oxalate, thiocyanate, isocyanate, isothiocyanate, carboxylate, and 
nitrate. The value of n is from 1 to 3 and satisfies the valency state of 
M. Suitable metal salts include, for example, zinc chloride, zinc bromide, 
zinc acetate, zinc acetonylacetate, zinc benzoate, zinc nitrate, iron(II) 
sulfate, iron(II) bromide, cobalt(II) chloride, cobalt(II) thiocyanate, 
nickel(II) formate, nickel(II) nitrate, and the like, and mixtures 
thereof. Zinc halides are preferred. 
The water-soluble metal cyanide salts used to make the double metal cyanide 
compounds useful in the invention preferably have the general formula 
(Mu).sub.a M'(CN).sub.b (A).sub.c in which M' is 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). More 
preferably, M' is selected from the group consisting of Co(II), Co(III), 
Fe(II), Fe(III), Cr(III), Ir(III), and Ni(II). The water-soluble metal 
cyanide salt can contain one or more of these metals. In the formula, Mu 
is an alkali metal ion or alkaline earth metal ion. A is an anion selected 
from the group consisting of halide, hydroxide, sulfate, carbonate, 
cyanide, oxalate, thiocyanate, isocyanate, isothiocyanate, carboxylate, 
and nitrate. Both a and b are integers greater than or equal to 1; the sum 
of the charges of a, b, and c balances the charge of M'. Suitable 
water-soluble metal cyanide salts include, for example, potassium 
hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium 
hexacyanoferrate(III), calcium hexacyanocobaltate(III), lithium 
hexacyanoiridate(III), and the like. 
Examples of double metal cyanide compounds that can be used in the 
invention include, for example, zinc hexacyanocobaltate(III), zinc 
hexacyanoferrate(III), zinc hexacyanoferrate(II), nickel(II) 
hexacyanoferrate(II), cobalt(II) hexacyanocobaltate(III), and the like. 
Further examples of suitable double metal cyanide compounds are listed in 
U.S. Pat. No. 5,158,922, the teachings of which are incorporated herein by 
reference. Zinc hexacyanocobaltates are preferred. 
The catalysts of the invention include an organic complexing agent 
comprising an alcohol and a cyclic, bidentate compound. The alcohol is a 
C.sub.3 -C.sub.5 aliphatic alcohol. Suitable alcohols include, for 
example, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, tert-butyl 
alcohol, tert-amyl alcohol, and the like, and mixtures thereof. Branched 
alcohols are preferred; tert-butyl alcohol is particularly preferred. 
In addition to the alcohol, the complexing agent includes a cyclic, 
bidentate compound selected from the group consisting of lactams and 
lactones. Preferably, the lactam or lactone is at least partially soluble 
in water. Especially preferred are C.sub.3 -C.sub.6 lactams and lactones. 
Lactams are cyclic amides. Many are conveniently produced by dehydrating 
common amino acids. The lactams can be substituted on the ring carbons or 
on the nitrogen atom with one or more alkyl, hydroxyalkyl, hydroxy, 
halogen, or alkoxy groups, or the like. Suitable lactams include, for 
example, .beta.-propiolactam, 2-pyrrolidone, 1-methyl-2-pyrrolidone 
(N-methylpyrrolidone), .delta.-valerolactam, .epsilon.-caprolactam, 
1-(2-hydroxyetyl)-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 
methyl-2-oxo-1-pyrrolidineacetate, and the like, and mixtures thereof. 
Particularly preferred are .delta.-valerolactam and pyrrolidones such as 
2-pyrrolidone and 1-methyl-2-pyrrolidone. 
Lactones are cyclic esters. Like the lactams, the lactones can contain ring 
substituents such as alkyl, hydroxyalkyl, hydroxy, halogen, or alkoxy 
groups, or the like. Suitable lactones include, for example, 
.beta.-propiolactone, .gamma.-butyrolactone, 67 -valerolactone, 
.epsilon.-caprolactone, and the like, and mixtures thereof. 
.gamma.-Butyrolactone is particularly preferred. 
Both the C.sub.3 -C.sub.5 aliphatic alcohol and the cyclic, bidentate 
compound are needed to give a catalyst that is highly active and also 
gives the desirable reduction in the amount of high-molecular-weight 
polyether component. If the cyclic, bidentate compound is omitted, the 
catalyst has high activity (like the ones disclosed in U.S. Pat. No. 
5,470,813), but polyols made from the catalyst can contain undesirable 
levels of the high-molecular-weight component. On the other hand, if only 
the cyclic, bidentate compound is present as the complexing agent, the 
catalysts tend to have relatively low activity and/or give polyols with 
broad molecular weight distributions and high viscosities. 
The relative amounts of C.sub.3 -C.sub.5 aliphatic alcohol to cyclic, 
bidentate compound needed in the catalyst can vary over a wide range, and 
a skilled person can control catalyst activity, polyol viscosity, and the 
like, by varying them. However, preferred catalysts will contain from 
about 5 to about 95 mole percent, based on the total amount of organic 
complexing agent, of the cyclic, bidentate compound. More preferred are 
catalysts that contain from about 10 to about 80 mole percent of the 
cyclic, bidentate compound; most preferred is the range from about 20 to 
about 60 mole percent. 
Catalysts of the invention optionally include a functionalized polymer or 
its water-soluble salt. By "functionalized polymer" we mean a polymer that 
contains one or more functional groups containing oxygen, nitrogen, 
sulfur, phosphorus, or halogen, wherein the polymer, or a water-soluble 
salt derived from it, has relatively good water solubility, i.e., at least 
about 3 wt. % of the polymer or its salt dissolves at room temperature in 
water or mixtures of water with a water-miscible organic solvent. Examples 
of water-miscible organic solvents are tetrahydrofuran, acetone, 
acetonitrile, t-butyl alcohol, and the like. Water solubility is important 
for incorporating the functionalized polymer, when used, into the catalyst 
structure during formation and precipitation of the double metal cyanide 
compound. 
Polyethers are preferred functionalized polymers. Catalysts that 
incorporate a polyether are taught in U.S. Pat. Nos. 5,482,908 and 
5,545,601, the teachings of which are incorporated herein by reference. A 
particularly preferred catalyst of the invention incorporates a polyether 
polyol as the functionalized polymer. 
Other suitable functionalized polymers include, for example, 
poly(acrylamide), poly(acrylic acid), poly(acrylic acid-co-maleic acid), 
poly(alkyl acrylate)s, poly(alkyl methacrylate)s, poly(vinyl methyl 
ether), poly(vinyl acetate), poly(vinyl alcohol), 
poly(N-vinylpyrrolidone), poly(N-vinylpyrrolidone-co-acrylic acid), 
poly(N,N-dimethylacrylamide), poly(4-vinylpyridine), poly(vinyl chloride), 
poly(acrylic acid-co-styrene), poly(vinyl sulfate), poly(vinyl sulfate) 
sodium salt, and the like. Many other suitable functionalized polymers are 
described in U.S. Pat. No. 5,714,428, the teachings of which are 
incorporated herein by reference. 
The functionalized polymer, when used, comprises from about 2 to about 80 
wt. % of the catalyst. Preferably, the catalyst contains from about 5 to 
about 70 wt. % of the functionalized polymer; most preferred is the range 
from about 10 to about 60 wt. %. 
Catalysts of the invention are preferably substantially non-crystalline. By 
"substantially non-crystalline," we mean lacking a well-defined crystal 
structure, or characterized by the substantial absence of sharp lines in 
the powder X-ray diffraction pattern of the composition. Conventional zinc 
hexacyanocobaltate-glyme catalysts (such as those described in U.S. Pat. 
No. 5,158,922) show a powder X-ray diffraction pattern containing many 
sharp lines, which indicates that the catalyst has a high degree of 
crystallinity. Zinc hexacyanocobaltate prepared in the absence of a 
complexing agent is also highly crystalline (and is inactive for epoxide 
polymerization). In contrast, catalysts of the invention are preferably 
substantially non-crystalline. 
Catalysts of the invention also feature unique infrared spectra. Many prior 
DMC catalysts, particularly the highly active, substantially 
non-crystalline varieties, exhibit absorption bands for free Zn--OH 
vibrations at 3650 cm.sup.-1 and 642 cm.sup.-1. In contrast, preferred 
catalysts of the invention lack these bands or have reduced absobances at 
these wavenumbers. These observations are significant because the lack of 
infrared absorption bands from free Zn--OH appears to correlate well with 
reduced formation of high-molecular-weight polyol components (see Examples 
1, 2, 4, and C10; Tables 1 and 2). In addition, catalysts of the invention 
uniquely show a low-energy carbonyl absorption (e.g., about 1630 cm.sup.-1 
for 2-pyrrolidones), which suggests the presence of a stable complex of 
the cyclic, bidentate compound and the DMC catalyst. 
The invention includes a method for making the catalysts. The method 
comprises reacting, preferably at a temperature within the range of about 
room temperature to about 80.degree. C., aqueous solutions of a metal salt 
(usually used in excess) and a metal cyanide salt in the presence of the 
organic complexing agent and optional functionalized polymer. The organic 
complexing agent components are included with either or both of the 
aqueous salt solutions, or they are added to the catalyst slurry 
immediately following precipitation of the DMC compound. It is generally 
preferred to pre-mix one or both of the complexing agent components with 
either aqueous solution, or both, before combining the reactants. The 
resulting catalyst is isolated (by centrifugation, filtration, decanting, 
or the like), washed, and dried as described previously (see, e.g., U.S. 
Pat. Nos. 5,470,813, 5,482,908, and 5,714,428, the teachings of which are 
incorporated herein by reference). 
In one preferred method of the invention, the cyclic, bidentate compound is 
included in one or both of the aqueous reactant solutions. In other words, 
it is included in the aqueous metal salt (e.g., zinc chloride) solution 
and/or the aqueous metal cyanide salt (e.g., potassium hexacyanocobaltate) 
solution before the two solutions are mixed. The reactant solutions are 
combined using efficient mixing (preferably by homogenization or 
high-shear stirring, e.g.) to produce a catalyst slurry that contains the 
DMC compound. The catalyst is then isolated, usually by filtration under 
pressure, and the residue is washed with an aqueous mixture that contains 
the C.sub.3 -C.sub.5 aliphatic alcohol. Optionally, this washing mixture 
also includes a functionalized polymer. The catalyst is then isolated as 
before, and additional washings with the C.sub.3 -C.sub.5 aliphatic 
alcohol or aqueous mixtures containing the alcohol and/or functionalized 
polymer are used. Preferably, the final wash uses no water. 
The method of the invention offers some valuable and unexpected benefits 
for catalyst manufacture that result from using a cyclic, bidentate 
compound. First, DMC catalysts made in the presence of the cyclic, 
bidentate compound are easier to filter than prior DMC catalysts, so the 
total amount of time needed to make them is reduced (see Example 15 and 
Comparative Example 16). Second, the cyclic, bidentate compound acts as a 
defoamer in the catalyst preparation, so less catalyst is deposited on the 
walls of the reactor used for catalyst manufacture. This results in 
improved catalyst consistency and less wasted catalyst. 
The invention includes a process for making an epoxide polymer. This 
process comprises polymerizing an epoxide in the presence of a DMC 
catalyst of the invention. Preferred epoxides are ethylene oxide, 
propylene oxide, butene oxides, styrene oxide, and the like, and mixtures 
thereof. The process can be used to make random or block copolymers. The 
epoxide polymer can be, for example, a polyether polyol derived from the 
polymerization of an epoxide in the presence of a hydroxyl 
group-containing initiator. 
Other monomers that will copolymerize with an epoxide in the presence of a 
DMC compound can be included in the process of the invention to make other 
types of epoxide polymers. Any of the copolymers known in the art made 
using conventional DMC catalysts can be made with the catalysts of the 
invention. For example, epoxides copolymerize with oxetanes (as taught in 
U.S. Pat. Nos. 3,278,457 and 3,404,109) to give polyethers, or with 
anhydrides (as taught in U.S. Pat. Nos. 5,145,883 and 3,538,043) to give 
polyester or polyetherester polyols. The preparation of polyether, 
polyester, and polyetherester polyols using DMC catalysts is fully 
described, for example, in U.S. Pat. Nos. 5,223,583, 5,145,883, 4,472,560, 
3,941,849, 3,900,518, 3,538,043, 3,404,109, 3,278,458, 3,278,457, and in 
J. L. Schuchardt and S. D. Harper, SPI Proceedings, 32nd Annual 
Polyurethane Tech./Market. Conf. (1989) 360. The teachings of these U.S. 
patents related to polyol synthesis using DMC catalysts are incorporated 
herein by reference in their entirety. 
Polyether polyols (or monols) made with the catalysts of the invention 
preferably have average hydroxyl functionalities from about 1 to 8, more 
preferably from about 2 to 6, and most preferably from about 2 to 3. The 
polyols preferably have number average molecular weights (Mn) within the 
range of about 500 to about 50,000. A more preferred range is from about 
1,000 to about 12,000; most preferred is the range from about 2,000 to 
about 8,000. 
The invention offers unexpected benefits for polyols. In particular, 
polyols made using DMC catalysts of the invention contain reduced levels 
of high-molecular-weight components compared with similar catalysts 
prepared without a cyclic, bidentate compound. The amount of 
high-molecular-weight component is quantified by any suitable method. A 
particularly convenient way to measure this component is by gel permeation 
chromatography (GPC). A suitable technique is described below in Example 
B. 
Polyols made according to the invention consistently contain less than 
about 10 ppm of polyether components having a number average molecular 
weight greater than 400,000 (i.e., Mn&gt;400K). Polyols made with most highly 
active DMC catalysts normally contain higher levels (at least 10 ppm) of 
material having Mn&gt;400K. While this reduction in the amount of 
high-molecular-weight polyol component may appear trivial, we surprisingly 
found that polyols of the invention consistently pass the "supercritical 
foam test" (SCFT)--a sensitive foam test designed to reveal whether or not 
polyols will cause foam settling or collapse in the field--while polyols 
made with other highly active DMC catalysts did not always pass the same 
test. Example A below explains how to practice the SCFT. 
The following examples merely illustrate the invention. Those skilled in 
the art will recognize many variations that are within the spirit of the 
invention and scope of the claims.

CATALYST PREATION EXAMPLES 
Example 1 
This example illustrates the preparation of a substantially non-crystalline 
zinc hexacyanocobaltate catalyst that incorporates 
1-(2-hydroxyethyl)-2-pyrrolidone (HEP) as a complexing agent in addition 
to tert-butyl alcohol and a 1000 mol. wt. polyether diol. 
Aqueous zinc chloride solution (120 g of 62.5 wt. % ZnCl.sub.2) is diluted 
with deionized water (230 g) and HEP (50 mL) in a one-liter beaker 
(Solution 1). Potassium hexacyanocobaltate (7.5 g) is dissolved in a 
second beaker with deionized water (100 mL) and HEP (20 mL) (Solution 2). 
Solution 3 is prepared by dissolving a 1000 mol. wt. polyoxypropylene diol 
(8.0 g) in deionized water (50 mL) and tetrahydrofuran (THF) (2 mL). 
Solution 2 is added to Solution 1 over 35 min. while homogenizing at 20% 
of maximum intensity. Following the addition, homogenization continues at 
40% intensity for 10 min. The homogenizer is stopped. Solution 3 is added, 
followed by slow stirring for 3 min. 
The reaction mixture is filtered at 40 psig through a 20 .mu.m nylon 
membrane. The catalyst cake is reslurried in a mixture of tert-butyl 
alcohol (130 mL) and deionized water (55 mL), and is homogenized at 40% 
intensity for 10 min. The homogenizer is stopped. More 1000 mol. wt. 
polyoxypropylene diol (2.0 g) dissolved in THF (2 g) is added, and the 
mixture is stirred slowly for 3 min. The catalyst is isolated as described 
above. The cake is reslurried in tert-butyl alcohol (185 mL) and 
homogenized as described above. More 1000 mol. wt. diol (1.0 g) in THF (2 
g) is added, and the product is isolated in the usual way. The resulting 
catalyst residue dried in a vacuum oven at 60.degree. C., 30 in. (Hg) to 
constant weight. 
Example 2 
The procedure of Example 1 is followed, except that a 50/50 mixture of 
N-methyl-2-pyrrolidone and tert-butyl alcohol replaces HEP in reactant 
Solutions 1 and 2. 
Example 3 
The procedure of Example 1 is followed, except that a 25/75 mixture of 
N-methyl-2-pyrrolidone and tert-butyl alcohol replaces HEP in reactant 
Solutions 1 and 2. 
Example 4 
The procedure of Example 1 is followed, except that poly(vinyl pyrrolidone) 
is used instead of the 1000 mol. wt. polyoxypropylene diol. 
Example 5 
The procedure of Example 1 is followed, except that a 50/50 mixture of 
2-pyrrolidone and tert-butyl alcohol replaces HEP in reactant Solutions 1 
and 2. 
Example 6 
The procedure of Example 1 is followed, except that a 25/75 mixture of 
2-pyrrolidone and tert-butyl alcohol replaces HEP in reactant Solutions 1 
and 2. 
Example 7 
The procedure of Example 1 is followed, except that a 10/90 mixture of 
.gamma.-butyrolactone and tert-butyl alcohol replaces HEP in reactant 
Solutions 1 and 2. 
Example 8 
The procedure of Example 1 is followed, except that a 25/75 mixture of 
.gamma.-butyrolactone and tert-butyl alcohol replaces HEP in reactant 
Solutions 1 and 2. 
Example 9 
The procedure of Example 1 is followed, except that .delta.-valerolactam 
(40 g in Solution 1, 10 g in Solution 2) replaces HEP. 
Comparative Example 10 
The procedure of Example 1 is followed, except tert-butyl alcohol replaces 
all of the HEP used. This catalyst is prepared essentially by the method 
of U.S. Pat. No. 5,482,908. 
As Examples 1-9 and Comparative Example 10 show (see Table 2), including a 
cyclic, bidentate compound in the preparation of a substantially 
non-crystalline double metal cyanide catalyst offers unexpected benefits. 
In particular, polyols made using the catalysts contain reduced levels of 
high-molecular-weight (&gt;400,000 mol. wt.) polyol component. In addition, 
the polyols perform better than the control polyols (ones made using a 
catalyst not prepared in the presence of a cyclic, bidentate compound) in 
the supercritical foam test, i.e., they exhibit a reduced level of 
settling compared with prior DMC-catalyzed polyols. 
Example 11 
This example illustrates the preparation of a substantially non-crystalline 
zinc hexacyanocobaltate catalyst that incorporates 
1-(2-hydroxyethyl)-2-pyrrolidone (HEP) as a complexing agent in addition 
to tert-butyl alcohol (but without a polyether diol). 
Aqueous zinc chloride solution (120 g of 62.5 wt. % ZnCl.sub.2) is diluted 
with deionized water (230 g) and HEP (50 mL) in a one-liter beaker 
(Solution 1). Potassium hexacyanocobaltate (7.5 g) is dissolved in a 
second beaker with deionized water (100 mL) and HEP (20 mL) (Solution 2). 
Solution 2 is added to Solution 1 over 40 min. while homogenizing at 20% 
of maximum intensity. Following the addition, homogenization continues at 
40% intensity for 10 min. 
The reaction mixture is filtered at 40 psig through a 20 .mu.m nylon 
membrane. The catalyst cake is reslurried in a mixture of tert-butyl 
alcohol (130 mL) and deionized water (55 mL), and is homogenized at 40% 
intensity for 10 min. The catalyst is isolated as described above. The 
cake is reslurried in tert-butyl alcohol (185 mL) and homogenized as 
described above. The catalyst is isolated as described above, and is dried 
in a vacuum oven at 60.degree. C., 30 in (Hg) to constant weight. 
Example 12 
The procedure of Example 11 is followed, except that 2-pyrrolidone replaces 
HEP in reactant Solutions 1 and 2. 
Comparative Example 13 
The procedure of U.S. Pat. No. 5,470,813 (Example 1) is used to prepare the 
catalyst. The complexing agent is tert-butyl alcohol only, and no 
polyether is included. 
As Examples 11-12 and Comparative Example 13 (see Table 3) show, the 
benefits of the invention are not limited to catalysts made in the 
presence of a functionalized polymer. In particular, polyols made using 
the catalysts of the invention contain reduced levels of 
high-molecular-weight (&gt;400,000 mol. wt.) polyol component and perform 
better than the control polyols in the supercritical foam test. 
Evaluation of Catalysts: Polyol Systhesis 
Example 14 
General procedure: Typical "slab" polyoxypropylene triols are prepared by 
adding propylene oxide over 2 hours to an activated mixture containing the 
zinc hexacyanocobaltate catalyst and a propoxylated glycerin starter 
(hydroxyl number=240 mg KOH/g). Catalyst levels of 30-100 ppm (see Tables 
2 and 3) are used. The hydroxyl number, viscosity, and polydispersity (by 
GPC) of each product is measured by standard methods. A GPC technique (see 
Example B) is used to measure the amount of polyol component having a 
number average molecular weight (Mn) greater than about 400,000, and the 
amount present (in ppm) is recorded in Tables 2 and 3. "N.D." means "none 
detected." 
Each polyol is also evaluated in the "supercritical foam test" (SCFT), 
which is described below in Example A. Each polyol's performance is 
compared against the performance of a KOH-based polyol (3000 mol. wt. 
polyoxypropylene triol) in the same test. The % settling of both samples 
is measured. The ratio of the % settle in the foam made using the KOH 
standard to the % settle in the foam made using the polyol to be tested is 
calculated. A ratio in the SCFT test of 0.6 or greater is deemed a "pass," 
while a ratio less than 0.6 fails. A ratio of 1.0 means that the tested 
polyol performs as well as a KOH-based polyol in the test; a ratio greater 
than 1 indicates that the sample outperforms (a "high pass") the KOH-based 
standard. For example, if the KOH-based polyol shows a % settle of 11%, 
and the tested polyol shows a % settle of 31%, the tested polyol has a 
KOH/sample ratio of 11/31=0.35, which fails the test. 
Example A 
Supercritical Foam Test (SCFT) 
Conventional one-shot flexible polyurethane foams are hand mixed and poured 
using the following "stressed" formulation. The formulation is 
characterized as stressed because it is intentionally made sensitive to 
the presence of high-molecular-weight polyol component. 
The B-side is prepared from the polyol sample to be analyzed (100 parts, 
typically a 3000 mol. wt. polyether triol), water (6.5 parts), 
dichloromethane (15 parts), A-1 catalyst (product of Witco, 0.1 parts), 
T-9 catalyst (product of Air Products, 0.25 parts), and L-550 surfactant 
(product of Witco, 0.5 parts). Toluene diisocyanate (78.01 parts, 110 
NCO/OH index) is rapidly added to the B-side components, the ingredients 
are mixed well and poured into a cake box. The foam rises and cures, and 
the % settling (or collapse) is noted. 
Example B 
Measurement of High Molecular Weight Polyol Component by Gel Permeation 
Chromatography (GPC) 
The molecular weight of the high molecular weight component of the polyol 
samples is quantified by comparing elution times in a GPC column with that 
of polystyrene samples of known molecular weights. The fraction of the 
sample having a number average molecular weight (Mn) greater than 400,000 
is then determined by standard methods. 
A Jordi Gel DVB 10.sup.3 angstrom column, 10.times.250 mm, 5 micron 
particle size, is employed with a mobile phase which consists of 
tetrahydrofuran. The detector is a Varex Model IIA evaporative light 
scanning detector. Polystyrene stock solutions are made from polystyrenes 
of different molecular weights by dilution with tetrahydrofuran to form 
standards containing 2, 5, and 10 mg/L of polystyrene. Samples are 
prepared by weighing 0.1 g of polyether polyol into a one-ounce bottle and 
adding tetrahydrofuran to the sample to adjust the total weight of the 
sample and solvent to 10.0 g. Samples of the calibration solutions are 
sequentially injected into the GPC column. Duplicates of each polyether 
polyol sample are then injected, followed by a reinjection of the various 
polystyrene standards. The peak areas for the standards are electronically 
integrated, and the electronically integrated peaks for the two sets of 
each candidate polyol are electronically integrated and averaged. For each 
sample, the fraction of material having Mn&gt;400,000 is calculated and 
reported. 
Example 15 and Comparative Example 16 
The procedure of Example 1 is generally followed, except that the times for 
each filtration step (see last paragraph of Example 1) are noted. The 
filtration times: first filtration: 4 min.; second: 6 min.; third: 4 min. 
For comparison, the filtration times are also noted in making a catalyst by 
the procedure of Comparative Example 10. The filtration times noted: first 
filtration: 17 min.; second: 32 min.; third: 4 min. 
The results demonstrate that catalysts made in the presence of a cyclic, 
bidentate compound are much easier to filter compared with prior DMC 
catalysts, so they will require less time to prepare them. 
The preceding examples merely illustrate the invention; the following 
claims define the scope of the invention. 
TABLE 1 
______________________________________ 
Catalyst Characterization 
Infrared Complexing agents 
spectrum (mole %).sup.1 
Absorbance, 
tert-butyl 
Ex # 642 cm.sup.-1 
alcohol HEP NMP Functionalized Polymer 
______________________________________ 
1 0 82 18 0 1K poly(PO) diol 
2 0 53 0 47 1K poly(PO) diol 
4 0 33 67 0 PVP 
C10 0.225 100 0 0 1K poly(PO) diol 
______________________________________ 
HEP = 1(2-hydroxyethyl)-2-pyrrolidone; NMP = Nmethyl-2-pyrrolidone; PVP = 
poly(vinyl pyrrolidone) 
.sup.1 Based on the total amount of tbutyl alcohol + the cyclic, bidentat 
compound. 
TABLE 2 
__________________________________________________________________________ 
Effect of Catalyst on Polyol Performance 
Catalyst ex. # 
1 2 3 4 5 6 7 8 9 C10 
__________________________________________________________________________ 
Other complex. agent 
HEP 50% 25% HEP 50% 25% 10% GBL 
25% GBL 
VL none 
(with t-butyl alcohol) 
NMP NMP PYR PYR 
Functionalized polymer 
1K diol 
1K diol 
1K diol 
PVP 1K diol 
1K diol 
1K diol 
1K diol 
1K diol 
1K diol 
ppm catalyst 
50 100 100 100 50 50 30 30 50 30 
Polyol properties 
Mw/Mn 1.09 
1.07 1.06 1.08 
1.09 
1.03 1.21 1.24 1.12 
1.03 
OH # (mg KOH/g) 
56.8 
56.9 56.3 56.8 
55.6 
55.1 56.1 55.7 57.3 
56.2 
Viscosity (cps) 
580 550 582 603 562 550 574 574 592 566 
&gt;400K mol. wt. (ppm) 
N.D. 
N.D. N.D. N.D. 
N.D. 
6 N.D. N.D. N.D. 
10 
SCFT: KOH/sample 
0.83 
1.25 0.60 0.74 
1.03 
0.64 0.81 0.71 0.99 
0.36 
Pass/Fail pass 
high pass 
low pass 
pass 
pass 
low pass 
pass pass pass 
fail 
__________________________________________________________________________ 
HEP = 1(2-hydroxyethyl)-2-pyrrolidone; NMP = Nmethyl-2-pyrrolidone; PYR = 
2pyrrolidone; GBL = butyrolactone; PVP = poly(vinyl pyrrolidone); VL = 
valerolactam. High molecular weight polyol component (by GPC) is the 
amount of sample with Mn &gt; 400,000; N.D. = none detected. 
TABLE 3 
______________________________________ 
Effect of Catalyst on Polyol Performance 
Catalyst ex. # 11 12 C13 
______________________________________ 
Other complexing agent 
HEP PYR none 
(with t-butyl alcohol) 
Functionalized polymer 
none none none 
ppm catalyst 50 50 50 
Polyol properties 
Mw/Mn 1.11 1.14 1.04 
OH # (mg KOH/g) 57.8 57.8 56.5 
Viscosity (cps) 591 616 567 
&gt;400K mol. wt. (ppm) 
N.D. N.D. 23 
SCFT results: KOH/sample 
0.67 1.0 0.28 
Pass/Fail pass pass fail 
______________________________________ 
HEP = 1(2-hydroxyethyl)-2-pyrrolidone; PYR = 2pyrrolidone. 
Highmolecular-weight polyol component (by GPC) is the amount of sample 
with Mn &gt; 400,000; N.D. = none detected.