Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Inorganic carbon containing
Reexamination Certificate
2002-05-10
2004-09-28
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Inorganic carbon containing
C502S200000, C502S159000, C502S172000, C423S367000
Reexamination Certificate
active
06797665
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention relates to double-metal cyanide (“DMC”) catalysts for preparing polyether polyols by the polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms.
BACKGROUND OF THE INVENTION
DMC catalysts for the polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms are known. DMC catalysts can be used to produce polyols which have low unsaturation levels compared with basic (KOH) catalysts. DMC catalysts can be used to produce polyether, polyester and polyetherester polyols which are useful in polyurethane coatings, elastomers, sealants, foams and adhesives.
DMC catalysts are typically obtained by reacting an aqueous solution of a metal salt (for example, zinc chloride) with an aqueous solution of a metal cyanide salt (for example, potassium hexacyanocobaltate), in the presence of an organic complexing ligand. The preparation of typical DMC catalysts is described, for example, in U.S. Pat. Nos. 3,427,256; 3,289,505; and 5,158,922.
Organic complexing ligands are needed in the preparation of DMC catalysts in order to obtain favorable catalytic activity. While water-soluble ethers (e.g., dimethoxyethane (“glyme”) or diglyme) and alcohols (for example, isopropyl alcohol or tert-butyl alcohol) are commonly used as the organic complexing ligand, other general classes of compounds have been described which are useful as the organic complexing ligand. For example, U.S. Pat. Nos. 4,477,589; 3,829,505; and 3,278,459 disclose DMC catalysts containing organic complexing ligands selected from alcohols, aldehydes, ketones, ethers, esters, amides, nitrites or sulphides.
DMC catalysts having increased activity for epoxide polymerization are known. For example, U.S. Pat. No. 5,470,813 discloses DMC catalysts which have higher activities compared with conventional DMC catalysts. U.S. Pat. Nos. 5,482,908 and 5,545,601 disclose DMC catalysts having increased activity which are composed of a functionalized polymer such as polyether.
Polyols produced in the presence of DMC catalysts which have increased activity can also have increased high (for example, greater than 400,000) molecular weight components. High molecular-weight components can negatively impact the product produced from the polyol. For example, polyols which have increased high molecular weight components can process poorly resulting in, for example, tight foams or foams which can settle or collapse. Various approaches have been proposed for addressing this problem. Such approaches include, for example, re-formulation of the polyurethane or removal of the component from the polyol after formation. These approaches, however, are not cost effective.
U.S. Pat. No. 6,013,596 discloses a DMC catalyst having increased activity and reduced levels of high molecular weight components. The DMC catalyst of this patent is composed of a C
3
-C
5
aliphatic alcohol and from about 5 to about 95 mol. %, based on the total amount of the organic complexing ligand, of a cyclic, bidentate compound selected from lactams and lactones.
There remains, however, a need for DMC catalysts which have increased activity compared to catalysts known in the art which can be used to produce polyols with reduced high molecular weight components.
SUMMARY OF THE INVENTION
DMC catalysts of the present invention are composed of: a) at least one DMC compound; b) at least one organic complexing ligand; and, optionally, c) at least one functionalized polymer, wherein the organic complexing ligand b) is a mixture of a C
3
-C
7
aliphatic alcohol and from about 2 to about 98 mole %, based on the total amount of organic complexing ligand, of a cyclic, aliphatic, cycloaliphatic or aromatic ketone.
DMC catalysts of the present invention have increased activity compared to catalysts known in the art. Additionally, polyols produced in the presence of the DMC catalysts of the present invention have reduced levels of high (having a number average molecular weight greater than 400,000) molecular weight components.
DESCRIPTION OF THE INVENTION
The present invention relates to a DMC catalyst composed of: a) at least one DMC compound; b) at least one organic complexing ligand; and c) optionally, at least one functionalized polymer, wherein the organic complexing ligand b) is a mixture of a C
3
-C
7
aliphatic alcohol and from about 2 to about 98 mole %, based on the total amount of organic complexing ligand, of a cyclic, aliphatic, cycloaliphatic or aromatic ketone.
DMC compounds useful in the present invention are the reaction products of water-soluble metal salts and water-soluble metal cyanide salts. Examples of suitable water-soluble metal salts useful in the present invention include 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, nickel(II) nitrate and mixtures thereof. Preferably, zinc halides are used in the present invention.
Examples of water-soluble metal cyanide salts useful in the present invention include potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithium hexacyanocobaltate(III). Preferably, potassium hexacyanocobaltates are used in the present invention.
Examples of suitable DMC compounds useful in the present invention include zinc hexacyanocobaltate(III), zinc hexacyanoiridate(III), zinc hexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III). Further examples of suitable DMC compounds useful in the present invention are disclosed in U.S. Pat. No. 5,158,922, the teachings of which are incorporated herein by reference. Zinc hexacyanocobaltates are preferred DMC compounds of the present invention.
Organic complexing ligands of the present invention are mixtures of at least one C
3
-C
7
aliphatic alcohol and at least one cyclic, aliphatic, cycloaliphatic or aromatic ketone.
Examples of suitable C
3
-C
7
aliphatic alcohols useful in the present invention include n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, tert-amyl alcohol and mixtures thereof. Preferably, C
3
-C
7
aliphatic alcohols used in the present invention are branched alcohols. More preferably, tert-butyl alcohols are used in the present invention.
Examples of suitable cyclic, aliphatic, cycloaliphatic or aromatic ketones useful in the present invention include methylethylketone, 3,3-dimethoxy-2-butanone, cyclopentanone, and cyclobutanone. Preferably, cyclopentanones are used in the present invention. More preferably, 3,3-dimethoxy-2-butanones are used in the present invention.
Both the C
3
-C
7
aliphatic alcohols and the ketones are needed to produce DMC catalysts which have increased activity compared to catalysts known in the art which can be used to produce polyols having reduced high molecular weight components. While DMC catalysts having a C
3
-C
7
aliphatic alcohol as the organic complexing ligand may have increased activity, the polyols produced from such DMC catalysts can contain undesirable levels of high molecular weight components. Also, DMC catalysts which have only a ketone as the organic complexing ligand tend to have relatively low activity and/or produce polyols with broad molecular weight distributions and high viscosities.
The relative amounts of C
3
-C
7
aliphatic alcohol and ketone used in the present invention can vary. A skilled person can control catalyst activity, polyol viscosity and the like by varying these amounts. Ketone is typically present in an amount from about 2 to about 98 mole %, preferably, from about 5 to about 95 mole %, more preferably, from about 10 to about 50 mole %, based on the total amount of organic complexing ligand.
DMC catalysts of the present invention can optionally include at least one of the same or different, or a combination or combinations of the same and different, functionalized polymer. “Functionalized polymer” is defined as a polymer or its salt which contains one
Bayer Antwerpen
Gil Joseph C.
Mrozinski, Jr. John E.
Wood Elizabeth D.
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