Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Inorganic carbon containing
Reexamination Certificate
2002-09-20
2004-02-24
Wood, Elizabeth (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Inorganic carbon containing
C502S200000
Reexamination Certificate
active
06696383
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to double-metal cyanide (“DMC”) catalysts which can be used to prepare polyols. The present invention is also directed to a process for preparing DMC catalysts. The present invention is further directed to a process for polymerizing an alkylene oxide in the presence of a DMC catalyst prepared according to the process of the present invention.
BACKGROUND OF THE INVENTION
In the preparation of polyoxyalkylene polyols, starter compounds having active hydrogen atoms are oxyalkylated with alkylene oxides in the presence of a suitable catalyst. For many years, basic as well as DMC catalysts have been used in oxyalkylation reactions to prepare polyoxyalkylene polyols. Base-catalyzed oxyalkylation involves oxyalkylating a low molecular weight starter compound (such as propylene glycol or glycerine) with an alkylene oxide (such as ethylene oxide or propylene oxide) in the presence of a basic catalyst (such as potassium hydroxide (KOH)) to form a polyoxyalkylene polyol.
In base-catalyzed oxyalkylation reactions, propylene oxide and certain other alkylene oxides are subject to a competing internal rearrangement which generates unsaturated alcohols. For example, when KOH is used to catalyze an oxyalkylation reaction using propylene oxide, the resulting product will contain allyl alcohol-initiated, monofunctional impurities. As the molecular weight of the polyol increases, the isomerization reaction becomes more prevalent. As a result, 800 or higher equivalent weight poly(propylene oxide) products prepared using KOH tend to have significant quantities of monofunctional impurities. Monofunctional impurities tend to reduce the average functionality and broaden the molecular weight distribution of the polyol.
Unlike basic catalysts, DMC catalysts do not significantly promote the isomerization of propylene oxide. As a result, DMC catalysts can be used to prepare polyols which have low unsaturation values and relatively high molecular weights. DMC catalysts can be used to produce polyether, polyester and polyetherester polyols which are useful in applications such as polyurethane coatings, elastomers, sealants, foams and adhesives.
DMC-catalyzed oxyalkylation reactions, however, are known to produce small amounts of high molecular weight polyol impurities (typically, molecular weights in excess of 100,000 Da). These high molecular weight impurities are often referred to as the “high molecular weight tail”. In elastomers and other systems, the high molecular weight tail may interfere with hard segment phase out as well as with the alignment of hard segments responsible for strength and modulus properties. In polyurethane foam systems, for example, polyols which have a high molecular weight tail produce course foam cells, very tight foams or weak foams or contribute to foam collapse.
DMC catalysts are known and are described in,;for example, U.S. Pat. Nos. 3,278,457, 3,278,459, 3,289,505, 3,427,256, 4,477,589, 5,158,922, 5,470,813, 5,482,908, 5,545,601, 5,627,122 and 6,423,662 as well as in WO 01/04180 and WO 02/09875. DMC catalysts are typically prepared by mixing an aqueous solution of a metal salt with an aqueous solution of a metal cyanide salt in the presence of an organic complexing ligand. A precipitate forms when these two solutions are mixed together. The resulting precipitate is isolated and then washed.
The art teaches that, during the preparation of a DMC catalyst, alkaline metal salts are incorporated into the catalyst. See Huang et al., “Controlled Ring-Opening Polymerization of Propylene Oxide Catalyzed by Double Metal-Cyanide Complex,”,
Journal of Polymer Science
, Vol.40, page 1144 (2002); U.S. Pat. No. 3,278,457, column 5, lines 40-44; and WO 02/09875, page 5, lines 5-12. The art also teaches that these occluded ions must be removed during the preparation of a DMC catalyst. See Huang et al., page 1144; U.S. Pat. No. 3,278,457, column 5, lines 57-58; and WO 02109875, page 5, lines 5-12. U.S. Pat. No. 6,423,662 (at column 6, lines 47-50), WO/01/04180 (at page 8, lines 17-19), and U.S. Pat. No. 3,278,457 (at column 5, lines 45-58), for example, teach those skilled in the art to wash the precipitate formed during the preparation of a DMC catalyst as thoroughly as possible in order to remove essentially all of these occluded ions.
SUMMARY OF THE INVENTION
The present invention is directed to process for preparing a DMC catalyst which involves combining: i) at least one metal salt; ii) at least one metal cyanide salt; iii) at least one organic complexing ligand; iv) at least one alkaline metal salt; and, optionally, v) at least one functionalized polymer.
The present invention is also directed to a process for preparing a polyol in the presence of a DMC catalyst prepared according to the process of the present invention.
The present invention is also directed to a DMC catalyst which is represented by the following general formula (I)
M
1
x
([M
2
x′
(CN)
y
]
z
.[M
3
(-x-)(A)
(-y-)]).L
1
.L
2
.M
4
(B)
z
(I)
Surprisingly, DMC catalysts of and produced by the process of the present invention, which are preferably prepared with at least one alkaline metal halide, have acceptable activity and can be used to catalyze oxyalkylation reactions.
Additionally, DMC catalysts produced by the process of the present invention can be used to produce polyols which have reduced levels of high molecular weight tail.
DESCRIPTION OF THE INVENTION
In a first aspect, the present invention is a process for preparing a DMC catalyst comprising combining: i) at least one metal salt; ii) at least one metal cyanide salt; iii) at least one organic complexing ligand; iv) at least one alkaline metal salt; and, optionally, v) at least one functionalized polymer, under conditions sufficient to form a catalyst.
In a second aspect, the present invention is a process for preparing a polyol comprising reacting i) at least one starter compound having active hydrogen atoms with ii) at least one oxide in the presence of iii) at least one DMC catalyst which is prepared according to the process of the present invention, under conditions sufficient to form a polyol.
In another aspect, the present invention is a DMC catalyst which is represented by the formula M
1
x
([M
2
x′
(CN)
y
]
z
.[M
3
(-x-)
(A)
(-y-)
]).L
1
.L
2
.M
4
(B)
z
,
wherein
M
1
represents at least one metal;
[M
2
x′
(CN)
y
] represents at least one metal cyanide;
[M
3
x
(A)
y
] represents at least one transition metal salt;
M
4
(B)
z
represents at least one alkali metal salt;
L
1
represents at least one organic complexing ligand;
L
2
is optional and can represent at least one functionalized polymer; and
x, x′, y and z are integers and are chosen such that electroneutrality of the DMC catalyst exists.
In yet another aspect, the present invention is a process for preparing a polyol comprising reacting i) at least one starter compound having active hydrogen atoms with ii) at least one oxide in the presence of iii) at least one DMC catalyst which is represented by the formula M
1
x
([M
2
x′
(CN)
y
]
z
.[M
3
(-x-)
(A)
(-y-)
]. L
1
.L
2
. M
4
(B)
z
.
wherein
M
1
represents at least one metal;
M
2
x′
(CN)
y
represents at least one metal cyanide;
[M
3
x
(A)
y
]. represents at least one transition metal salt;
M
4
(B)
z
represents at least one alkaline metal salt;
L
1
represents at least one organic complexing ligand;
L
2
is optional and can represent at least one functionalized polymer; and
x, x′, y and z are integers and are chosen such that electroneutrality of the DMC catalyst exists.
Any metal salt can be used in the present invention. Preferably, water soluble metal salts which are known in the art are used in the present invention. Examples of metal salts which are useful in the present invention include, for example, zinc chloride, zinc bromide, zinc acetate, zinc cetylacetonate, zinc benzoate, zinc nitrate, zinc propionate, zinc formate, iron(II)
Le-Khac Bi
Wang Wei
Bayer Polymers LLC
Gil Joseph C.
Mrozinski, Jr. John E.
Wood Elizabeth
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