CA2023634A1 - Process for the removal of catalysts from polyether polyols - Google Patents
Process for the removal of catalysts from polyether polyolsInfo
- Publication number
- CA2023634A1 CA2023634A1 CA002023634A CA2023634A CA2023634A1 CA 2023634 A1 CA2023634 A1 CA 2023634A1 CA 002023634 A CA002023634 A CA 002023634A CA 2023634 A CA2023634 A CA 2023634A CA 2023634 A1 CA2023634 A1 CA 2023634A1
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- CA
- Canada
- Prior art keywords
- polyether polyol
- water
- polyether
- temperature
- carbon dioxide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/34—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from hydroxy compounds or their metallic derivatives
- C08G65/46—Post-polymerisation treatment, e.g. recovery, purification, drying
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/30—Post-polymerisation treatment, e.g. recovery, purification, drying
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyethers (AREA)
- Polyurethanes Or Polyureas (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
A PROCESS FOR THE REMOVAL OF
CATALYSTS FROM POLYETHER POLYOLS
ABSTRACT OF THE DISCLOSURE
The present invention thus relates to a process for removing a basic catalyst from a polyether polyol having a hydroxyl number of from about 4 to 800 comprising (a) adding from about 0.7 to 10 percent by weight of water, based on said polyether polyol, to an alkaline medium containing said polyether polyol at a temperature of from about 25 to 140°C;
(b) introducing about 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from about 75 to 120°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding inorganic and/or organic acids.
CATALYSTS FROM POLYETHER POLYOLS
ABSTRACT OF THE DISCLOSURE
The present invention thus relates to a process for removing a basic catalyst from a polyether polyol having a hydroxyl number of from about 4 to 800 comprising (a) adding from about 0.7 to 10 percent by weight of water, based on said polyether polyol, to an alkaline medium containing said polyether polyol at a temperature of from about 25 to 140°C;
(b) introducing about 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from about 75 to 120°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding inorganic and/or organic acids.
Description
~6~ 34 Mo3437 A PROCESS FOR THE REMOVAL OF
CATALYSTS FROM POLYETHER POLYOLS
BACKGROUND OF THE INVENTION
The present invention relates to a process for the removal from polyether polyols of basic catalysts that remain in these products after their preparation is completed. The removal of catalyst is effected by hydrolysis and introduction of carbon dioxide, with subsequent filtering off of the carbonate formed. Finally, the residual base content is adjusted to any desired level by post-neutralization with acids, preferably oxalic acid.
Polyoxyalkylene polyether polyols, also known simply as polyether polyols, are particularly useful for the preparation of polyurethanes. The polyether polyols are most commonly reacted with polyisocyanates and give urethane polymers, which can be in the form of either elastomers or semi-rigid or rigid foams. For example, European Application --~ -116,309, German Auslegeschrift 1,~29,034, German Offenlegungsschrift 2,019,322, and Ullmanns Encyklopadie der technischen Chemie (Ullmanns Encyclopedia of Industrial Chemistry), vol. 19, page 31 et seq. Polyether polyols can also be used as textile auxiliaries, surfac~ants, hydraulic fluids, ingredients of paints and adhesives, and lubricants.
The properties of the polyurethanes depend to a great -~
extent on the polyether polyols and isocyanates used, as well as on the corresponding additives, such as, for example, catalysts. Accordingly, the polyether polyols must be present in very pure form and substantially free from impurities that could act as catalysts in the polyurethane-forming reaction.
Polyether polyols can be prepared on a large industrial scale by the polyaddition reaction of alkylene oxides on starter molecules containing active hydrogen atoms.
See, for example, Ullmanns Encyklopadie der technischen Chemie (Ullmanns Encyclopedia of Industrial Chemistry), vol. 19, page Le A 26 956 ~ r ' ' ' ' ~ ' , . ~ , ' ~ 3 ~ 3 '~
CATALYSTS FROM POLYETHER POLYOLS
BACKGROUND OF THE INVENTION
The present invention relates to a process for the removal from polyether polyols of basic catalysts that remain in these products after their preparation is completed. The removal of catalyst is effected by hydrolysis and introduction of carbon dioxide, with subsequent filtering off of the carbonate formed. Finally, the residual base content is adjusted to any desired level by post-neutralization with acids, preferably oxalic acid.
Polyoxyalkylene polyether polyols, also known simply as polyether polyols, are particularly useful for the preparation of polyurethanes. The polyether polyols are most commonly reacted with polyisocyanates and give urethane polymers, which can be in the form of either elastomers or semi-rigid or rigid foams. For example, European Application --~ -116,309, German Auslegeschrift 1,~29,034, German Offenlegungsschrift 2,019,322, and Ullmanns Encyklopadie der technischen Chemie (Ullmanns Encyclopedia of Industrial Chemistry), vol. 19, page 31 et seq. Polyether polyols can also be used as textile auxiliaries, surfac~ants, hydraulic fluids, ingredients of paints and adhesives, and lubricants.
The properties of the polyurethanes depend to a great -~
extent on the polyether polyols and isocyanates used, as well as on the corresponding additives, such as, for example, catalysts. Accordingly, the polyether polyols must be present in very pure form and substantially free from impurities that could act as catalysts in the polyurethane-forming reaction.
Polyether polyols can be prepared on a large industrial scale by the polyaddition reaction of alkylene oxides on starter molecules containing active hydrogen atoms.
See, for example, Ullmanns Encyklopadie der technischen Chemie (Ullmanns Encyclopedia of Industrial Chemistry), vol. 19, page Le A 26 956 ~ r ' ' ' ' ~ ' , . ~ , ' ~ 3 ~ 3 '~
31 et seq. ~he resultant polyether polyols have free hydroxyl groups, some of which, however, are terminated by alcoholate groups because of the alkaline reaction medium. The alcoholate groups can be converted into free hydroxyl groups in a 5 subsequent step. The alkali-containing polyether polyol preparations are generally neutralized with inorganic or organic acids to produce polyether polyols containing hydroxyl groups and aqueous salt solutions. The water is then removed by distillation and the salts are separated from the polyether o polyols by filtration. Alternatively, the polyether polyol can be separated by centrifugation and/or phase separation, either with or without the addition of inert solvents. ~;
If inorganic acids, such as sulfuric acid, phosphoric -~
acid, hydrochloric acid, potassium hydrogen phosphate, and the ~ -like, or organic acids, such as citric acid, tartaric acid9 and -the like, are used for the neutralization, the neutralization ~ -must be carried out to the exact equivalence point. This precision is intended to assure, on the one hand, a minimum of residual basic alkali salts and, on the other hand, a minimum 20 . of excess acid. Furthermore, the alkali salt is often precipitated in such a fine form that filtration is difficult despite the use of filtration aids. The use of strong acids can also lead to side reactions, such as esterification, etherification, and/or dehydration of terminal hydroxyl groups, 25 ~ and/or to the degradation of the polyether chains. Polyethers damaged in this way can contain unpleasant odor components.
Another method for removal of the catalyst is hydrolysis of the alcoholate and subsequent phase separation using inert organic solvents. See U.S. Patent 3,715,402. The phase separat;on can be aided by centrifugation or electrostatic coalescence, but such variants on the process are limited to water-insoluble polyether polyols.
The use of magnesium silicates as absorbents for the removal of aqueous potassium hydroxide is described in a number 35- of patents, for example, German Offenlegungsschrift 2,208,614 Le A 26 956 , ~ ~ q~
and U.S. Patents 4,029,879 and 4,137,396. The resultant filtration residue, which consists of potassium hydroxide-magnesium silicate and polyether polyol, is difficult to handle and too problematical to dispose of. In addition, losses in yield are relatively high.
U.S. Patent 3,833,669 teaches inter alia that when removing catalysts by neutralization with carbon dioxide, the catalyst is inadequately neutralized and the very fine crystals alkali metal carbonates are difficultly filtered.
Consequently, the polyether polyols thus obtained do not have the desired degree of purity. This patent recommends the use of magnesium carbonates to form sparingly soluble alkali metal-magnesium carbonate double salts. The disadvantages of this process include the handling and disposal of the filtration residue. The use of large stoichiometric excesses of carbon dioxide (two- to ten-fold, plus exhaust gas disposal) and magnesium salts (one to 20 times the catalyst content, plus waste disposal) is unsatisfactory. In addition, filter aids in -q quantities of 0.1 to 1% of the amount of polyether polyol are required for separation and are further obstacles to further -use of the residues.
Therefore, the object of the present invention was to provide a simple and reliable process for the removal of catalyst residues from polyether polyols without the disadvantages discussed above.
SUMMARY OF THE INVENTION
The present invention thus relates to a process for removing a basic catalyst from a polyether polyol having a hydroxyl number of from about 4 to about 800 comprising (a) adding from about 0.7 to about 10 percent by weight of -~
water, based on said polyether polyol, to an alkaline medium containing said polyether polyol and said basic catalyst at a temperature of from about 25 to about 140DC;
(b) introducing about 1 to about 2 times the stoichiometric ~-amount of gaseous carbon dioxide, based on the amount of Le A 26 956 ~ c `: : ~
~'J ~
base in the alkaline reaction medium, at a temperature of from about 75 to about 120C, thereby forming a carbonate ¦ salt;
I (c) removing said carbonate salt by filtration to give a ¦ 5 filtrate containing the polyether polyol; and ~-(d) neutralizing said filtrate by adding inorganic and/or organic acids (preferably oxalic acid).
DETAILED DESCRIPTION OF THE INVENTION
It has surprisingly been found that if suitable reaction conditions and parameters are selected, basic catalysts can be very effectively removed by carbonate salt formation. The resultant carbonate salts unexpectedly precipitate as coarse crystals, so that filtrat;on does not present problems, even in the absence of filter aids.
Polyether polyols having OH values of 4 to 150 contain less -~
than 10 ppm residual alkali. Polyether polyols having OH
values above 150 contain up to 1,000 ppm residual alkali.
It has surprisingly been found that the content of excessive residual alkali can be reduced to any desired level by subsequent neutralization with relatively strong acids, followed by filtration of the resultant salts. Suitable such acids include inorganic acids, such as sulfuric acid or phosphoric acid, and organic acids such as tartaric acid or other carboxylic acids, especially oxalic acid. It has also been found that polyether polyols neutralized solely with carbon dioxide and then post-neutralized with organic acids are substantially odorless when compared to products which have been worked up using mineral acids. ~ -The use of gaseous carbon dioxide and carboxylic acids, particularly oxalic acid, advantageously avoids unwanted secondary reactions, such as esterification, dehydration, or over-acidification; allows easy removal of the excess carbon dioxide; allows the formation of substantially odorless polyether polyols; and prevents corrosion by mineral acids.
:
Le A 26 956 ~:
r~
' . "~ ~ ' ~ ,', ' ~'~' ~ ' ' , ' , , ' -`' 3 ~
Suitable polyether polyols for use in the process of the invention have a hydroxyl number of about 4 to about 250 and are prepared by known methods, such as described in -~
Saunders and Frisch, Polvurethanes: Chemistrv and TechnoloqY - -Part I (1962), pages 32 to 40. The preparation of such polyether polyols typically involves the use of strongly basic catalysts. For example, suitable catalysts that can be removed according to the present invention include alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, and the like.
The alkali metal carbonates formed in the process of the invent;on contain metal ions corresponding to those of the ;
alkali metal catalysts originally used to form the polyether polyols. These carbonate salts can be isolated in such pure form that they can be used as raw materials, for example, in the production of glass, ceramics, and enamels.
The process according to the invention is carried out by the following general procedure. In step (a~ of the process of the invention, the alkaline polyaddition product, which contains at least some alkoxide groups under the reaction conditions, is hydrolyzed by addition of water to the alkaline medium, typically at a temperature in the range of about 25 to about 140C. The catalyst is then neutralized in step (b) by introducing gaseous carbon dioxide at a temperature in the range of about 75 to about 120C. The carbonate salt is removed by filtration, either before or after distillation to remove the added water. After determination of the residual alkali content, the polyol-containing filtrate is post-neutralized with acid (particularly oxalic acid), redistilled, and filtered. Known antioxidants can be added, -particularly during the post-neutralization, to prevent -~
deterioration of the poly~l, e.~. B.H.T (Di-tert.-Butyl-~ydroxy-Toluene).
In a preferred embodiment of the invention, the alkaline polyaddition product is hydrolyzed by addition of 35- about 0.7 to 10.0 wt.% of water at a temperature of about 75 to Le A 26 956 ~;y.~
...... . ~ :
,_, 2~3~1;3~ ".
120-C. Gaseous carbon dioxide is then passed through with ~-stirring at about 75 to 120C (preferably 80 to 95C) in an amount corresponding to about 1 to about 2 times the stoichiometric requirement determined by the amount of base in the alkaline medium. The water is removed under atmospheric pressure or in vacuo at a temperature of about 90 to about 130-C. The carbonate salt which precipitates is filtered off, optionally with the assistance of a filtering aid, such as cellulose fiber or the like if appropriate. Water may again be remoYed as before, giving the product polyether polyol.
After determination of the residual alkali content, the product is subjected to post-neutralization using 60 to 100% of the stoichiometric quantity of oxalic acid. The salt precipitate is filtered off, optionally after the removal of water.
The following examples further illustrate details for the process of this invention. The invention, which is set forth in the foregoing disclosure, is not to be limited either in spirit or scope by these examples. Those skilled in the art will readily understand that known variations of the conditions 20.. of the following procedures can be used. Unless otherwise noted, all temperatures are degrees Celsius and all percentages and parts are percentages by weight and parts by weight.
EXAMPLES
Example 1 To 5841 g of a polyether of glycerol and butylene oxide ("butox") (OH number 546) containing 0.5 wt.% KOH was added 290 9 of water at 90-C. The mixture was stirred for 0.5 hour at 90-C and neutralized with 13.7 9 of gaseous carbon dioxide. The carbonate was filtered off and the resultant 30 product was analyzed.
Analysis:
Base content (KOH, ppm): 707 ppm Water content (wt.%): 4.64%
Le A 26 956 :; - : :: ~ , .
&:.
~:: .: , '' :
~2~3~
The treated polyether was then stirred with 26.7 9 of water, 3.64 9 of oxalic acid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) 177 ppm ~ -Water content (wt.%) 0.05%
ExamDle 2 To 6839 9 of a polyether of sugar, propylene glycol, water, and propylene oxide ("PO") (OH number 470) containing o 0.5 wt.% KOH was added 341.5 9 of water at 90C. The mixture was stirred for one hour at 90C and neutralized with 19.3 9 of gaseous carbon dioxide. The mixture was stirred with 0.1%
filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 650 ppm Water content (wt.%):
A 5322 9 portion of the treated polyether was then stirred with 23.6 9 of water, 3.1 9 of oxalic acid, 0.1%
cellulose-based filter aid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) 130 ppm Water content (wt.%) 0.06%
ExamDle 3 To 5690 9 of a polyether of trimethylolpropane and propylene oxide ("PO") (OH number 380) containing 0.5 wt.% KOH
was added 569 9 of water at 90C. The mixture was stirred for one hour at 90C and neutralized with 13.5 9 of gaseous carbon 30 dioxide. The mixture was stirred with 0.1% filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 477 ppm 35 - Water content (wt.%): -Le A 26 956 ~J~34 A 5400 9 portion of the treated polyether was ~hen stirred with 55R.5 9 of water, 2.44 9 of oxalic acid, 0.1%
filter aid, and antioxidants. ~ater was removed at 110C and the product was filtered.
Analysis:
Base content (KOH, ppm) 54 ppm ~ater content (wt.%) 0.05%
ExamDle 4 To 4500 9 of a polye~her of sorbitol, propylene oxide (~PO~), and ethylene oxide (~EOn) (OH number 175) containing 0.4 wt.~ KOH was added 569 9 of water at 90-C. The mixture was stirred for one hour at 90-C and neutralized with 13.5 9 of gaseous carbon dioxide. The mixture was stirred with 0.1%
cellulose-based filter aid, water was removed, and the carbonate was filtered off. The resultant product was analyzed.
Analysis:
Base content (KOH, ppm): 75 ppm ~ater content (wt.%J: -The treated polyether was then stirred with 26.7 9 ofwater, 3.64 9 of oxalic acid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) lO ppm ~ater content (wt.%) 0.06%
x mple 5 To 3814 9 of a polyether of trimethylolpropane and propylene oxide (OH number 380) containing 0.25 wt.% KOH was added 440 9 of water at 90-C. The mixture was stirred for 0.5 hour at 90-C and neutralized with 8.71 9 of gaseous carbon dioxide. The mixture was stirred with O.lX cellulose-based filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 398 ppm ~ater content (wt.%): 0.02%
~e A 26 956 :, ~ ~: - , . .
: . . . ~ . . .
3 ~ 3 ~1 g A 4513 g portion of the treated polyether was then stirred for two hours at 80~C with 225 9 of water and 2.36 g of 85% phosphoric acid. Water was removed, the product was filtered, and the product was analyzed.
Analysis:
Base content (KOH, ppm) 67.5 ppm Water content (wt.%) 0.07%
ExamDle 6 A polyether (5130 g) was neutralized with carbon o dioxide as in Example 3, followed by removal of water and filtration.
A 4000 g portion of the treated polyether was then stirred for one hour at 98C with a solution of 2.06 g of tartaric acid in 40 9 water and antioxidants. Water was removed, the product was filtered, and the product was analyzed.
Analysis:
Base content (KOH, ppm) 150 ppm Water content (wt.%) 0.05%
. ~;
Le A 26 956 ~ ~
-: -:
If inorganic acids, such as sulfuric acid, phosphoric -~
acid, hydrochloric acid, potassium hydrogen phosphate, and the ~ -like, or organic acids, such as citric acid, tartaric acid9 and -the like, are used for the neutralization, the neutralization ~ -must be carried out to the exact equivalence point. This precision is intended to assure, on the one hand, a minimum of residual basic alkali salts and, on the other hand, a minimum 20 . of excess acid. Furthermore, the alkali salt is often precipitated in such a fine form that filtration is difficult despite the use of filtration aids. The use of strong acids can also lead to side reactions, such as esterification, etherification, and/or dehydration of terminal hydroxyl groups, 25 ~ and/or to the degradation of the polyether chains. Polyethers damaged in this way can contain unpleasant odor components.
Another method for removal of the catalyst is hydrolysis of the alcoholate and subsequent phase separation using inert organic solvents. See U.S. Patent 3,715,402. The phase separat;on can be aided by centrifugation or electrostatic coalescence, but such variants on the process are limited to water-insoluble polyether polyols.
The use of magnesium silicates as absorbents for the removal of aqueous potassium hydroxide is described in a number 35- of patents, for example, German Offenlegungsschrift 2,208,614 Le A 26 956 , ~ ~ q~
and U.S. Patents 4,029,879 and 4,137,396. The resultant filtration residue, which consists of potassium hydroxide-magnesium silicate and polyether polyol, is difficult to handle and too problematical to dispose of. In addition, losses in yield are relatively high.
U.S. Patent 3,833,669 teaches inter alia that when removing catalysts by neutralization with carbon dioxide, the catalyst is inadequately neutralized and the very fine crystals alkali metal carbonates are difficultly filtered.
Consequently, the polyether polyols thus obtained do not have the desired degree of purity. This patent recommends the use of magnesium carbonates to form sparingly soluble alkali metal-magnesium carbonate double salts. The disadvantages of this process include the handling and disposal of the filtration residue. The use of large stoichiometric excesses of carbon dioxide (two- to ten-fold, plus exhaust gas disposal) and magnesium salts (one to 20 times the catalyst content, plus waste disposal) is unsatisfactory. In addition, filter aids in -q quantities of 0.1 to 1% of the amount of polyether polyol are required for separation and are further obstacles to further -use of the residues.
Therefore, the object of the present invention was to provide a simple and reliable process for the removal of catalyst residues from polyether polyols without the disadvantages discussed above.
SUMMARY OF THE INVENTION
The present invention thus relates to a process for removing a basic catalyst from a polyether polyol having a hydroxyl number of from about 4 to about 800 comprising (a) adding from about 0.7 to about 10 percent by weight of -~
water, based on said polyether polyol, to an alkaline medium containing said polyether polyol and said basic catalyst at a temperature of from about 25 to about 140DC;
(b) introducing about 1 to about 2 times the stoichiometric ~-amount of gaseous carbon dioxide, based on the amount of Le A 26 956 ~ c `: : ~
~'J ~
base in the alkaline reaction medium, at a temperature of from about 75 to about 120C, thereby forming a carbonate ¦ salt;
I (c) removing said carbonate salt by filtration to give a ¦ 5 filtrate containing the polyether polyol; and ~-(d) neutralizing said filtrate by adding inorganic and/or organic acids (preferably oxalic acid).
DETAILED DESCRIPTION OF THE INVENTION
It has surprisingly been found that if suitable reaction conditions and parameters are selected, basic catalysts can be very effectively removed by carbonate salt formation. The resultant carbonate salts unexpectedly precipitate as coarse crystals, so that filtrat;on does not present problems, even in the absence of filter aids.
Polyether polyols having OH values of 4 to 150 contain less -~
than 10 ppm residual alkali. Polyether polyols having OH
values above 150 contain up to 1,000 ppm residual alkali.
It has surprisingly been found that the content of excessive residual alkali can be reduced to any desired level by subsequent neutralization with relatively strong acids, followed by filtration of the resultant salts. Suitable such acids include inorganic acids, such as sulfuric acid or phosphoric acid, and organic acids such as tartaric acid or other carboxylic acids, especially oxalic acid. It has also been found that polyether polyols neutralized solely with carbon dioxide and then post-neutralized with organic acids are substantially odorless when compared to products which have been worked up using mineral acids. ~ -The use of gaseous carbon dioxide and carboxylic acids, particularly oxalic acid, advantageously avoids unwanted secondary reactions, such as esterification, dehydration, or over-acidification; allows easy removal of the excess carbon dioxide; allows the formation of substantially odorless polyether polyols; and prevents corrosion by mineral acids.
:
Le A 26 956 ~:
r~
' . "~ ~ ' ~ ,', ' ~'~' ~ ' ' , ' , , ' -`' 3 ~
Suitable polyether polyols for use in the process of the invention have a hydroxyl number of about 4 to about 250 and are prepared by known methods, such as described in -~
Saunders and Frisch, Polvurethanes: Chemistrv and TechnoloqY - -Part I (1962), pages 32 to 40. The preparation of such polyether polyols typically involves the use of strongly basic catalysts. For example, suitable catalysts that can be removed according to the present invention include alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, and the like.
The alkali metal carbonates formed in the process of the invent;on contain metal ions corresponding to those of the ;
alkali metal catalysts originally used to form the polyether polyols. These carbonate salts can be isolated in such pure form that they can be used as raw materials, for example, in the production of glass, ceramics, and enamels.
The process according to the invention is carried out by the following general procedure. In step (a~ of the process of the invention, the alkaline polyaddition product, which contains at least some alkoxide groups under the reaction conditions, is hydrolyzed by addition of water to the alkaline medium, typically at a temperature in the range of about 25 to about 140C. The catalyst is then neutralized in step (b) by introducing gaseous carbon dioxide at a temperature in the range of about 75 to about 120C. The carbonate salt is removed by filtration, either before or after distillation to remove the added water. After determination of the residual alkali content, the polyol-containing filtrate is post-neutralized with acid (particularly oxalic acid), redistilled, and filtered. Known antioxidants can be added, -particularly during the post-neutralization, to prevent -~
deterioration of the poly~l, e.~. B.H.T (Di-tert.-Butyl-~ydroxy-Toluene).
In a preferred embodiment of the invention, the alkaline polyaddition product is hydrolyzed by addition of 35- about 0.7 to 10.0 wt.% of water at a temperature of about 75 to Le A 26 956 ~;y.~
...... . ~ :
,_, 2~3~1;3~ ".
120-C. Gaseous carbon dioxide is then passed through with ~-stirring at about 75 to 120C (preferably 80 to 95C) in an amount corresponding to about 1 to about 2 times the stoichiometric requirement determined by the amount of base in the alkaline medium. The water is removed under atmospheric pressure or in vacuo at a temperature of about 90 to about 130-C. The carbonate salt which precipitates is filtered off, optionally with the assistance of a filtering aid, such as cellulose fiber or the like if appropriate. Water may again be remoYed as before, giving the product polyether polyol.
After determination of the residual alkali content, the product is subjected to post-neutralization using 60 to 100% of the stoichiometric quantity of oxalic acid. The salt precipitate is filtered off, optionally after the removal of water.
The following examples further illustrate details for the process of this invention. The invention, which is set forth in the foregoing disclosure, is not to be limited either in spirit or scope by these examples. Those skilled in the art will readily understand that known variations of the conditions 20.. of the following procedures can be used. Unless otherwise noted, all temperatures are degrees Celsius and all percentages and parts are percentages by weight and parts by weight.
EXAMPLES
Example 1 To 5841 g of a polyether of glycerol and butylene oxide ("butox") (OH number 546) containing 0.5 wt.% KOH was added 290 9 of water at 90-C. The mixture was stirred for 0.5 hour at 90-C and neutralized with 13.7 9 of gaseous carbon dioxide. The carbonate was filtered off and the resultant 30 product was analyzed.
Analysis:
Base content (KOH, ppm): 707 ppm Water content (wt.%): 4.64%
Le A 26 956 :; - : :: ~ , .
&:.
~:: .: , '' :
~2~3~
The treated polyether was then stirred with 26.7 9 of water, 3.64 9 of oxalic acid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) 177 ppm ~ -Water content (wt.%) 0.05%
ExamDle 2 To 6839 9 of a polyether of sugar, propylene glycol, water, and propylene oxide ("PO") (OH number 470) containing o 0.5 wt.% KOH was added 341.5 9 of water at 90C. The mixture was stirred for one hour at 90C and neutralized with 19.3 9 of gaseous carbon dioxide. The mixture was stirred with 0.1%
filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 650 ppm Water content (wt.%):
A 5322 9 portion of the treated polyether was then stirred with 23.6 9 of water, 3.1 9 of oxalic acid, 0.1%
cellulose-based filter aid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) 130 ppm Water content (wt.%) 0.06%
ExamDle 3 To 5690 9 of a polyether of trimethylolpropane and propylene oxide ("PO") (OH number 380) containing 0.5 wt.% KOH
was added 569 9 of water at 90C. The mixture was stirred for one hour at 90C and neutralized with 13.5 9 of gaseous carbon 30 dioxide. The mixture was stirred with 0.1% filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 477 ppm 35 - Water content (wt.%): -Le A 26 956 ~J~34 A 5400 9 portion of the treated polyether was ~hen stirred with 55R.5 9 of water, 2.44 9 of oxalic acid, 0.1%
filter aid, and antioxidants. ~ater was removed at 110C and the product was filtered.
Analysis:
Base content (KOH, ppm) 54 ppm ~ater content (wt.%) 0.05%
ExamDle 4 To 4500 9 of a polye~her of sorbitol, propylene oxide (~PO~), and ethylene oxide (~EOn) (OH number 175) containing 0.4 wt.~ KOH was added 569 9 of water at 90-C. The mixture was stirred for one hour at 90-C and neutralized with 13.5 9 of gaseous carbon dioxide. The mixture was stirred with 0.1%
cellulose-based filter aid, water was removed, and the carbonate was filtered off. The resultant product was analyzed.
Analysis:
Base content (KOH, ppm): 75 ppm ~ater content (wt.%J: -The treated polyether was then stirred with 26.7 9 ofwater, 3.64 9 of oxalic acid, and antioxidants. Water was removed and the product was filtered.
Analysis:
Base content (KOH, ppm) lO ppm ~ater content (wt.%) 0.06%
x mple 5 To 3814 9 of a polyether of trimethylolpropane and propylene oxide (OH number 380) containing 0.25 wt.% KOH was added 440 9 of water at 90-C. The mixture was stirred for 0.5 hour at 90-C and neutralized with 8.71 9 of gaseous carbon dioxide. The mixture was stirred with O.lX cellulose-based filter aid, water was removed, and the carbonate was filtered off. The resultant product was then analyzed.
Analysis:
Base content (KOH, ppm): 398 ppm ~ater content (wt.%): 0.02%
~e A 26 956 :, ~ ~: - , . .
: . . . ~ . . .
3 ~ 3 ~1 g A 4513 g portion of the treated polyether was then stirred for two hours at 80~C with 225 9 of water and 2.36 g of 85% phosphoric acid. Water was removed, the product was filtered, and the product was analyzed.
Analysis:
Base content (KOH, ppm) 67.5 ppm Water content (wt.%) 0.07%
ExamDle 6 A polyether (5130 g) was neutralized with carbon o dioxide as in Example 3, followed by removal of water and filtration.
A 4000 g portion of the treated polyether was then stirred for one hour at 98C with a solution of 2.06 g of tartaric acid in 40 9 water and antioxidants. Water was removed, the product was filtered, and the product was analyzed.
Analysis:
Base content (KOH, ppm) 150 ppm Water content (wt.%) 0.05%
. ~;
Le A 26 956 ~ ~
-: -:
Claims (6)
1. A process for removing a basic catalyst from a polyether polyol having a hydroxyl number of from 4 to 800 comprising (a) adding from 0.7 to 10 percent by weight of water, based on said polyether polyol, to an alkaline medium containing said polyether polyol and said basic catalyst at a temperature of from 25 to 140°C;
(b) introducing 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from 75 to 120°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding an inorganic and/or organic acid.
(b) introducing 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from 75 to 120°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding an inorganic and/or organic acid.
2. A process according to Claim 1 wherein step (a) is carried out at a temperature of from 75 to 120°C.
3. A process according to Claim 1 wherein carbon dioxide is introduced in step (b) at a temperature of from 80 to 95°C.
4. A process according to Claim 1 wherein one or more filter aids are used in filtration step (c).
5. A process according to Claim 1 wherein the acid used in step (d) is oxalic acid.
6. A process according to Claim 1 for removing a basic catalyst from a polyether polyol having a hydroxyl number of from 4 to 800 comprising (a) adding from about 0.7 to about 10 percent by weight of water, based on said polyether polyol, to an alkaline medium containing said polyether polyol and said basic catalyst at a temperature of from 75 to 120°C;
(b) introducing 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from 80 to 95°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration using one or more filter aids to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding oxalic acid.
(b) introducing 1 to 2 times the stoichiometric amount of gaseous carbon dioxide, based on the amount of base in the alkaline reaction medium, at a temperature of from 80 to 95°C, thereby forming a carbonate salt;
(c) removing said carbonate salt by filtration using one or more filter aids to give a filtrate containing the polyether polyol; and (d) neutralizing said filtrate by adding oxalic acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3928151A DE3928151A1 (en) | 1989-08-25 | 1989-08-25 | METHOD FOR REMOVING CATALYSTS FROM POLYETHER POLYOLS |
| DEP3928151.5 | 1989-08-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2023634A1 true CA2023634A1 (en) | 1991-02-26 |
Family
ID=6387883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002023634A Abandoned CA2023634A1 (en) | 1989-08-25 | 1990-08-20 | Process for the removal of catalysts from polyether polyols |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0414070A3 (en) |
| JP (1) | JPH0397730A (en) |
| KR (1) | KR910004706A (en) |
| AU (1) | AU6124290A (en) |
| BR (1) | BR9004169A (en) |
| CA (1) | CA2023634A1 (en) |
| DD (1) | DD298121A5 (en) |
| DE (1) | DE3928151A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11572440B2 (en) | 2020-02-18 | 2023-02-07 | Covestro Llc | Methods for purifying polyols containing oxyalkylene units to reduce 2-methyl-2-pentenal content |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5095950B2 (en) * | 2006-03-03 | 2012-12-12 | 株式会社カネカ | Method for producing polyether |
| JP2013506732A (en) * | 2009-10-02 | 2013-02-28 | ビーエーエスエフ ソシエタス・ヨーロピア | Odor reducing polyol composition and method for producing the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3715402A (en) * | 1969-08-08 | 1973-02-06 | Basf Wyandotte Corp | Removal of catalysts from polyols |
| JPS5241698A (en) * | 1975-09-30 | 1977-03-31 | Sanyo Chem Ind Ltd | Process for the purification of polyethers |
-
1989
- 1989-08-25 DE DE3928151A patent/DE3928151A1/en not_active Withdrawn
-
1990
- 1990-08-11 EP EP19900115431 patent/EP0414070A3/en not_active Withdrawn
- 1990-08-20 CA CA002023634A patent/CA2023634A1/en not_active Abandoned
- 1990-08-22 AU AU61242/90A patent/AU6124290A/en not_active Abandoned
- 1990-08-23 BR BR909004169A patent/BR9004169A/en unknown
- 1990-08-23 JP JP2220185A patent/JPH0397730A/en active Pending
- 1990-08-23 DD DD90343599A patent/DD298121A5/en not_active IP Right Cessation
- 1990-08-23 KR KR1019900013010A patent/KR910004706A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11572440B2 (en) | 2020-02-18 | 2023-02-07 | Covestro Llc | Methods for purifying polyols containing oxyalkylene units to reduce 2-methyl-2-pentenal content |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3928151A1 (en) | 1991-02-28 |
| KR910004706A (en) | 1991-03-29 |
| EP0414070A2 (en) | 1991-02-27 |
| AU6124290A (en) | 1991-02-28 |
| BR9004169A (en) | 1991-09-03 |
| EP0414070A3 (en) | 1991-03-13 |
| JPH0397730A (en) | 1991-04-23 |
| DD298121A5 (en) | 1992-02-06 |
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