Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-12-20
2002-07-23
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C252S182240, C252S182250, C252S182260, C252S182270, C521S128000, C521S129000
Reexamination Certificate
active
06423759
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to co-initiated polyether polyols useful for the production of rigid polyurethane foams and to a process for the production of such co-initiated polyols.
Processes for the production of polyether polyols from materials which are normally solid at ambient conditions such as sucrose are known. In many of the known processes, the solid material is dissolved or suspended in a solvent prior to reaction with the selected alkylene oxide(s) to facilitate processing of the reaction mixture. The solvent can either be an inert material such that disclosed in U.S. Pat. No. 3,941,769 or a reactive material such as water (U.S. Pat. No. 5,596,059).
The presence of water or an inert organic solvent during the reaction of the solid material with the alkylene oxide, however, is undesirable for a number of reasons. First, the solvent takes up space in the reactor which might otherwise be used to produce larger batches of polyol. Second, the solvent or unreacted water must be removed, usually by distillation. Such removal consumes both time and energy. Finally, if water is used to suspend or dissolve the sucrose, difunctional glycols which reduce the average functionality of the polyol produced are formed. One proposed solution to this problem is removal of the solvent by distillation after a portion of the alkylene oxide has been added. (See, e.g., U.S. Pat. No. 3,085,085 which discloses removal of water by distillation.) Such removal of water after adding and reacting a portion of the total alkylene oxide desired reduces the amount of glycols formed and allows for a larger batch size but still consumes time and energy.
In commercial processes for the production of polyurethane foams, mixtures or blends of individual polyols are generally used as the polyol component to be reacted with the isocyanate component. Use of such mixtures makes it possible to produce polymers having specific physical properties suited for a particular application.
When developing new systems, combination of individual polyols makes it easier to optimize a system for the production of polymers having a desired combination of properties. However, once a system has been optimized, the flexibility achieved by use of individual polyols is no longer necessary. This is particularly true where one or more of the polyols in the optimized system is difficult to manufacture such as polyols based on solid initiators such as sucrose. In such cases, it may be desirable to produce a co-initiated polyol which duplicates the properties obtained from the blend of individual polyols.
In U.S. Pat. No. 5,684,057, for example, a polyol composition to produce a rigid foam having improved thermal insulation and dimensional stability when specified blowing agents were used was sought. The polyol composition developed includes at least three different types of polyol. The polyol composition required in this patented process includes: (1) an aromatic amine-initiated polyether polyol, (2) an aliphatic amine-initiated polyether polyol, and (3) a polyester polyol. This patent teaches that the individual polyols may be combined prior to reaction with the polyisocyanate. It is preferred, however, that the aromatic amine-initiated and aliphatic amine-initiated polyols be prepared by a co-initiation process in which the aliphatic and aromatic amine initiators are first blended together and the resultant blend is subsequently alkoxylated. The required polyester polyol is then added to the propoxylated blend.
U.S. Pat. No. 5,596,059 discloses polyol blends for the production of flexible foams which do not require the use of expensive initiators such as glycerine or of solvents such as toluene. These polyol blends are prepared by alkoxylating aqueous solutions of one or more solid, polyhydric, hydroxy-functional initiators to produce a blend of low functionality diols and higher functionality polyols. A key feature of this process, is the alkoxylation of the water used as solvent. This alkoxylation of water eliminates the need for water removal and the need to use expensive conventional initiators such as glycerine or solvents. Water co-initiated polyols such as these, however, are not useful for the production of rigid polyurethane foams because of their low functionalities and hydroxyl numbers.
A polyol blend for the production of rigid polyurethane foams which could be prepared from a solid polyhydroxyl compound initiator by a simple process without the need to use a solvent would, therefore, be advantageous.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the production of a co-initiated polyether polyol from a polyhydroxyl compound that is normally solid at processing conditions without the need to use large quantities of a solvent that must be removed prior to use of that co-initiated polyol and without generating large amounts of low functionality diols.
It is also an object of the present invention to provide a more efficient and economical process for the production of a co-initiated polyether polyol having a functionality of at least 4 from a polyhydroxyl compound that is normally solid at processing conditions.
It is a further object of the present invention to provide a co-initiated polyol for the production of rigid polyurethane foams which produces foams having properties comparable to foams made with polyols formed by the conventional method for producing blends, i.e., combining individual polyols.
These and other objects which will be apparent to those skilled in the art are accomplished by suspending a solid polyhydroxyl initiator having a functionality of at least 4 and a melting or decomposition point above 95° C. in an amine-initiated polyol, heating the suspension, (preferably, in the presence of an alkaline catalyst) and alkoxylating the resultant mixture. The alkaline catalyst may then be neutralized and/or removed from the alkoxylated mixture. The alkoxylation product may then be used in a process for the production of rigid polyurethane foams.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to a new method for producing co-initiated polyether polyols from polyhydroxyl compounds that are solids at ambient temperature without the use of an inert solvent such as toluene or the large quantities of water necessary to suspend or dissolve the solid polyhydroxy compound. In this method, at least one solid polyhydroxyl compound is suspended in at least one amine-initiated polyol, the suspension is heated to or maintained at a temperature of at least 80° C. in the presence of an alkaline catalyst and subsequently alkoxylated. The alkaline catalyst is then neutralized and/or removed from the alkoxylated mixture by any of the known techniques such as neutralization with sulfuric acid or lactic acid, extraction or decantation. The resultant alkoxylated mixture may then be used to prepare rigid polyurethane foams.
The solid polyhydroxyl compounds useful as the initiator to be suspended in the amine-initiated polyol have a hydroxyl group functionality of at least 4 and melt at temperatures above 95° C. or decompose before melting. Examples of suitable polyhydroxyl compound initiators include: pentaerythritol, dipentaerythritol, glucose, sorbitol, lactose, mannitol, fructose, sucrose, hydrolyzed starches, saccharide and polysaccharide derivatives such as alpha-methylglucoside and alpha-hydroxyethyl-glucoside. Sorbitol, sucrose, and pentaerythritol are particularly preferred.
The amine-initiated polyol in which the solid polyhydroxyl compound is suspended may be any of the known amine-initiated polyether polyols which is liquid at temperatures of from about 70 to about 150° C., has a viscosity at the processing temperature which is sufficiently low that it will form a suspension that can be stirred, and has a hydroxyl number sufficiently high that upon alkoxylation the co-initiated polyether polyol product will have the predetermined hydroxyl number of greater than 300 mg KOH/g. The hydroxyl number of the amine-initiate
Ball Edward E.
Doerge Herman P.
Headley Keith J.
Schilling Steven L.
Bayer Corporation
Cooney Jr. John M.
Gil Joseph C.
Whalen Lyndanne M.
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