POLYETHER THICKENERS FOR WATER-BASED HYDRAULIC FLUIDS

Abstract: Alpha olefin oxide-capped polyether polyols are prepared by reacting a substantially anhydrous heteric or block copolymer of ethylene oxide and a lower alkylene oxide with an alpha olefin oxide in the presence of a catalyst. The capped polyether polyols are useful as thickeners for aqueous systems, such as water-based hydraulic fluids.

Description: Polyether Thickeners for Water-Based Hydraulic Fluids Background of the Invention This invention pertains to novel alpha oiefin oxide-capped polyether polyols which are particularly suitable for use as thickeners for aqueous systems, such as water-based hydraulic fluids. Water-soluble or water-dispersible thickeners of a variety of chemical types are used in aqueous liquids to increase their viscosity. In recent years, by reason of their lower cost, as compared to petroleum oils, efforts have been made to provide water-based hydraulic fluids of acceptable properties. Because of the substantially lower viscosity of water-based hydraulic fluids, as compared to those based on petroleum oils, various types of polyether polyols have been suggested for used therein as thickeners. However, in order to obtain hydraulic fluids having a viscosity of at least 200 Sabolt Universal Seconds (SUS) at 100° P., it has been necessary to use substantial amounts of polyether pόlyol thickeners of relatively high molecular weight. In addition to the cost disadvantages due to the substantial quantities of such thickeners which must be used to obtain the desired viscosity, such thickeners in use evidence a reduction in molecular weight by reason of the shearing forces to which they are subjected, whereby a significant decrease in the viscosity of the hydraulic fluid occurs. Summary of the Invention This invention relates to novel thickeners for aqueous-based hydraulic fluids. The thickeners are polyether polyols which have been capped with an aliphatic alpha oiefin oxide containing from about 10 to about 30 carbon atoms. The polyether polyols which are capped are obtained by reacting ethylene oxide and a lower alkylene oxide having 3 to 4 carbon atoms with an active hydrogen compound which is a polyhydric alcohol to form a heteric or block copolymer. The reaction by which such copolymers may be capped may be illustrated as follows: H0CH2CH 2 C(CH3)CHCH2θ] x [CH2CH2θ]yCH2CHCH 3 OH HOCH CH 2 [(CH3)CHCH2θ] χ [CH2CH2θ]yCH 2 CHCH2θ-CH2CHOH -R in which x and y are integers and R is an aliphatic chain containing from 8 to 28, preferably from 12 ot 20 carbon atoms. Surprisingly, it was discovered that such capped polyether polyols have considerably greater thickening power than similar high molecular weight uncapped polyether polyols. Thus, a much lesser quantity of the new polyols is required to provide aqueous-based hydraulic fluids of a given viscosity. In addition, and of equal importance, was the discovery that the new capped polyether polyols are shear stable as a result of which hydraulic fluids in which they are employed undergo only relatively small reductions in viscosity even after hundreds of hours of use. Description of the Preferred Embodiments In preparing the capped polyether polyol thickeners of this invention, the polyether polyols are first prepared by reacting ethylene oxide, at least one lower alkylene oxide having 3 to 4 carbon atoms, and an active hydrogen compound which is a polyhydric alcohol. OMPI Methods for preparing these polyether polyols are well known, and good results may be obtained by bringing a mixture containing the ethylene oxide and the lower alkylene oxide into intimate contact with the aliphatic polyhydric alcohol active hydrogen compound in the liquid phase, throughout which a suitable catalyst is uniformly dispersed. As catalysts, sodium and potassium hydroxide are preferred. The reaction is carried out at temperatures on the order of 50° to 160° C, under a pressure of from about 20 to about 100 psig. The concentration of the catalyst may vary from about 0.1 to about 5 percent by weight of the active hydrogen compound. Besides ethylene oxide, the lower alkylene oxides used in the reaction include 1,2-propylene oxide, and butylene oxide. The percentages by weight of these components vary from about 10 to about 90 percent of ethylene oxide, to from about 90 to 10 percent of another lower alkylene oxide or mixture thereof. Preferably the copolymers, which may be either heteric or block, contain about 65 to about 85 percent ethylene oxide and about 35 to about 15 percent lower alkylene oxide containing 3 to 4 carbon atoms. A particularly preferred polyether polyol is a block copolymer comprising 75 percent ethylene oxide and 25 percent 1,2-propylene oxide. The reactive hydrogen compounds or initiators employed in preparing the polyether polyols which are then capped with -an aliphatic alpha oiefin oxide are selected from the group consisting of alkane polyols, alkene polyols, alkyne polyols and oxyalkylene polyols. The alkane polyols should contain from about 2 to about 10 carbon atoms from about 2 to about 6 hydroxyl groups. Examples of such alkane polyols are ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, trimethylol propane, pentaerythritol and the like. The alkene polyols, like the alkane polyols, may have from 2 to 10 carbon atoms and 2 to 6 hydroxyl groups. Useful alkene polyols include 2-butene-l,4-diol, 2-hexene-l,4,6-triol, l,5-hexadiene-3,4-diol, and the like. Examples of alkyne polyols, which may also contain the same number of carbon atoms and hydroxyl groups as the alkane and alkene polyols, are 2-butyne-l,4-diol, 2-hexyne-l,4,6-triol and 4-octyne-l,2,7,8-tetrol. Of the oxyalkylene polyols, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol and tripropyleπe glycol are preferred active hydrogen compounds. Generally a relatively minor amount of initiator or active hydrogen compound, e.g. on the order of 10 percent or less, by weight, based on the combined weight of the alkylene oxide monomers and initiator need be used to prepare the polyether polyols which are capped according to the invention. The polyether polyols which are to be capped generally will have a molecular weight of about 5000 to about 75,000, preferably from about 10,000 to about 15,000. Such polyether polyols in which the active hydrogen compound is a polyol and the process for their preparation are described in detail in U.S. Patent No. 2,425,845, the disclosure of which is incorproated herein by reference. For further details on the preparation of block copolymers see U.S. Patent No. 3,535,307 which is incorported herein by reference. [SIX^*- The aliphatic alpha oiefin oxides which are used to cap the polyether polyols described hereinabove, are those containing on the order of from about 10 to about 30 carbon atoms, preferably from about 12 to about 18 carbon atoms. The amount of alpha oiefin oxide required to obtain the improved thickeners of this invention is generally from about 1 to about 20 percent, preferably from about 1 to about 10 percent, by weight of the capped polyether polyol. Examples of preferred alpha oiefin oxides are 1,2-epoxy hexadecane, 1,2-epoxy heptadecane, 1,2-epoxy octadecane, and mixtures thereof. In capping the polyether polyols, it is preferred that such reactant first be rendered substantially anhydrous. This may be accomplished by heating the polyether polyol in the presence of an organic solvent, such as toluene or xylene, under reflux conditions for several hours, following which the solvent is stripped to remove water. BF3 catalyst, preferably in ether, is added to the reaction vessel under a blanket of an inert gas such as nitrogen. In the alternative, an alkaline catalyst such as sodium hydroxide, sodium methoxide or potassium hydroxide may be used in place of BF3. Such alkaline catalyst may be an anhydrous solid or in the form of a concentrated aqueous solution. However, where the catalyst is in the form of an aqueous solution, the catalyst and polyol should be combined following which water is removed to provide anhydrous reactants as hereinabove described. The alpha oiefin oxide is then added and the reaction takes place over a period of several hours in the absence of heat. During the reaction, reaction temperatures should be maintained in the range of from about 45 to about 50° C, although such temperatures may be as high as 155° C, particularly where an alkaline catalyst is employed. In order that the invention may be better understood several examples thereof will now be described, purely by way of illustration, without suggestion that the scope of the invention is limited to the details thereof. Example I 1400 grams of a block copolymer comprising 75 percent, by weight of ethylene oxide and 25 percent 1,2-propylene oxide and having a molecular weight of 12,000-15,000 (ϋcon 75H 90,000, Union Carbide Corp.) and 100 grams of xylene were placed in a 2 liter, three neck flask and heated under reflux for about five and a half hours, following which the xylene was stripped under a vacuum of 24" mercury to remove substantially all of the water initially present in the copolymer. The flask was blown with nitrogen for 10 seconds and, after cooling the contents of the flask to 72° C, 5 ml. of a mixture of BF3 (47%) in ether were added and the contents of the flask were stirred for one hour. The heat source was removed and 130 grams of a mixture of aliphatic alpha oiefin oxides containing from 16 to 18 carbon atoms were added, and the reaction mixture was stirred for five hours to produce the capped polyether polyol thickener. Example II A hydraulic fluid was prepared by combining the following constituents: TABLE I Constituents We ight Percent Thickener of Example I 9. 0 Ethylene glycol 33.0 Vapor phase corrosion inhibitor* 2. 0 Copper corrosion inhibitor** 0.5 Morpholine 0.5 Soft water 55.0 * Dibutylamine caprate ** Sodium mercaptobenzothiazole The hydraulic fluid, which had a hazy opaque appearance, had a viscosity of 420 SUS at 100°F. , a pH of 9.2 and a specific gravity of about 1.07 at 60° F. The hydraulic fluid was subjected to the following pump test: TABLE II Pump Vickers V-104-A-10 Vane Pump Pressure, psi 900 Output (theoretical) gpm 5 Sump temperature °F 120 + 5°F Duration, hrs. 168 TEST RESULTS Ring Wear Loss, mgs 175 Wear Rate, gs/hr. 1.04 Viscosity Loss, % 12.4 Example III 4582 grams of a block copolymer comprising 75 percent, by weight of ethylene oxide and 25 percent 1,2-propylene oxide and having a molecular weight of 12,000-15,000 (Ucon 75H 90,000, Union Carbide Corp.) and 400 grams of xylene were placed in a 2 liter, three neck flask and heated under reflux for about six hours, following which the xylene was stripped under a vacuum of 20-24" mercury to remove substantially all of the water initially present in the .copolymer. The flask was blown with nitrogen for 10 seconds, and after cooling the contents of the flask to 50° C., 15 ml. of a mixture of BF3 (47%) in ether were added, and the contents of the flask were stirred for one hour. The heat source was removed and 382 grams of a mixture of aliphatic alpha oiefin oxides containing from 16 to 18 carbon atoms were added, and the reaction mixture was stirred for five hours to provide a capped polyether polyol thickener. Example IV A hydraulic fluid was prepared by combining the following constituents: TABLE III Constituents Weight Percent Thickener of Example III 7. .5 Ethylene glycol 35. .5 Vapor phase corrosion inhibitor* 1, .0 Copper corrosion inhibitor** 0. .5 Morpholine 0. .5 Soft water 55. .0 * Dibutyla ine caprate ** Sodium mercaptobenzothiazole The hydraulic fluid, which had a hazy opaque color, had a viscosity of 152 SUS at 100° F., a pH of 9.0-9.4 and a specific gravity of about 1.07. The hydraulic fluid was subjected to the following test: TABLE IV Pump Viσkers V-104- -A- -10 Vane Pump Pressure, psi 900 Output (theoretical) ggppm 5.0 Sump temperature °F 120 + 5 °F Duration, hrs. 212 TEST RESULTS Ring wear loss, mgs. 801 Vane wear loss, mgs. 34 Total wear loss, mgs. 835 Wear rate, mgs/hr. 3.9 Viscosity loss, % 5.3 Example V To a 3 liter, 3 neck flask prepared for heating and agitation were added 120 g. of a block copolymer comprising about 75 percent by weight of ethylene oxide and 25 percent of 1,2-propylene oxide and having a molecular weight of about 2000 (Ucon 75H 1400, Union Carbide Corp.), 25 g. of a mixture of aliphatic alpha oiefin oxides having from 16 ot 18 carbon atoms, and 1 ml. of a mixture comprising BF3 (47%) in ether were added, and the reaction mixture was heated for a period of approximately 25 minutes. A capped polyether polyol thickener for aqueous systems was obtained. Example VI To a 250 ml. beaker fitted with a stainless steel stirrer were introduced 100 g. of a heteric copolymer of ethylene oxide and 1,2-propylene oxide, 20 g. of a mixture of aliphatic alpha oiefin oxides containing from 16 to 18 carbon atoms and 1 mg. of a mixture of BF3 (47%) in ether. The reaction mixture was stirred and the temperature of the mixture increased from 26° C. to 34° C. over the approximately 1 hour reaction OMPI reaction time. The resulting capped polyether polyol thickener was used to formulate a hydraulic fluid containing 10 percent by weight of the thickener, 25 percent polypropylene glycol and 65 percent water. Example VII To a 3 liter, 3 neck flask prepared for heating and agitation were added 920 g. of a block copolymer comprising 75 percent by weight of ethylene oxide and about 25 percent of 1,2-propylene oxide (M.W. 15,500), 80 g. of toluene and 218 g. of a 45 percent aqueous solution of potassium hydroxide. The mixture was blended and heated at 110 - 115° C. for 3-4 hours under a vacuum of 25-28" Hg., following which a nitrogen purge was used to remove water and toluene. 38 g. of a mixture of aliphatic oiefin oxides having from 16 to 18 carbon atoms were added and the reaction mixture was maintained at 150-155° C for 2 hours. A capped polyether polyol thickener for aqueous systems was obtained.

Claims: Claims 1. A polyether polyol particularly useful for thickening aqueous systems, said polyether polyol having a molecular weight of from about 5000 to about 75,000 and having been prepared by reacting ethylene oxide and at least one lower alkylene oxide having 3 to 4 carbon atoms with at least one polyhydric alcohol selected from the group consisiting of alkane polyols, alkene polyols, alkyne polyols and oxyalkylene polyols to prepare a heteric or block copolymer, and further reacting said copolymer with a lower aliphatic alpha oiefin oxide having from about 10 to about 30 carbon atoms and wherein said alpha oiefin oxide is present in the amount of from about 1 percent to about 20 percent by weight based on the total weight of said copolymer and alpha oiefin oxide. 2. A polyether polyol of claim 1 prepared by copolymerizing a mixture of ethylene oxide and said lower alkylene oxide to form a heteric copolymer and subsequently reacting said copolymer with said alpha oiefin oxide. 3. A polyether polyol of claim 1 prepared by reacting ethylene oxide with a lower alkylene oxide to form a block copolymer and subequently reacting said copolymer with said alpha oiefin oxide. 4. A polyether polyol according to claim 3 in which said lower alkylene oxide is 1,2-propylene oxide. _ OMPI_ 5. A polyether polyol according to claim 1 in which the proportion of ethylene oxide to lower alkylene oxide employed in preparing said copolymer is from about 65 to about 85 percent by weight of ethylene oxide and from about 35 to about 15 lower alkylene oxide. 6. A polyether polyol according to claim 1 in which said polyhydric alcohol is an alkane polyol. 7. A polyether polyol according to claim 6 in which said polyhydric alcohol is ethylene glycol. 8. A polyehter polyol according to claim 6 in which said polyhydric alcohol is diethylene glycol. 9. A polyether polyol according to claim 1 in which said aliphatic alpha oiefin oxide contains from 12 to 18 carbon atoms. 10. A polyether polyol according to claim 1 in which said alpha oiefin oxide comprises a mixture of 1,2-epoxy hexadecane, 1,2-epoxy heptadecane and 1,2-epoxy octadecane. 11. A polyether polyol particularly useful for thickening aqueous systems, said polyether polyol having a molecular weight of from about 10,000 to about 15,000 and having been prepared by reacting from about 75 percent, by weight of ethylene oxide, and about 25 percent of 1,2-propylene oxide with an alkane polyol selected from the group consisting of ethylene glycol and diethylene glycol to prepare a block copolymer, and further reacting said copolymer with a mixture of 1,2-epoxy hexadecane, 1,2-epoxy heptadecane and 1,2-epoxy octadecane. 12. A process for preparing a polyether polyol particularly suitable for thickening aqueous systems which comprises reacting a substantially anhydrous copolymer of ethylene oxide and a lower alkylene oxide containing 3 to 4 carbon atoms with an aliphatic alpha oiefin oxide having about 12 to 18 carbon atoms in the presence of a catalyst selected from the group consisting of boron trifluoride, sodium hydroxide, sodium methoxide and potassium hydroxide, said alpha oiefin oxide being present in the amount of from about 1 to about 10 percent by weight, based on the total weight of copolymer and alpha oiefin oxide. 13. A process according to claim 12 in which said copolymer is prepared by reaction of from about 65 to about 85 percent by weight of ethylene oxide with from about 35 to about 15 percent of lower alkylene oxide. 14. A process according to claim 12 in which said copolymer is a block copolymer containing about 75 percent by weight of ethylene oxide and about 25 percent of 1,2-propylene oxide, and said alpha oiefin oxide comprises a mixture of 1,2-epoxy hexadecane, 1,2-epoxy heptadecane and 1,2-epoxy octadecane.

Inventors: COSTAGLIOLA EMIL J, MUNJAT FRANCIS S, COSTAGLIOLA, EMIL, J., MUNJAT, FRANCIS, S. (DECEASED)
Applicants: HOUGHTON & CO E F, E. F. HOUGHTON & CO.
Application year: 1983
Main classification: C07C43
IPC codes: C08G65, C10M173