Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/20—Antifreeze additives therefor, e.g. for radiator liquids

Definitions

• the present invention relates generally to heat transfer fluids and, more specifically, to an anti freeze concentrate characteri zed by superior stability.
• organophosphate esters have been disclosed for use as lubricants and corrosion inhibitors.
• ethylene oxide-containing organophosphates and propylene oxide-containing organophosphates and a method of preparing them are disclosed in U.S. Patent 4,360,474.
• German patent application 2,756,747 discloses PO/EO and PO/BO-containing phosphate esters (wherein "EO” denotes ethylene oxide, "PO” denotes propylene oxide, and “BO” denotes butylene oxide) useful as lubricants and corrosion inhibitors.
• EO denotes ethylene oxide
• PO denotes propylene oxide
• BO denotes butylene oxide
• the compounds of this publication are made by reacting polyphosphoric acid with aliphatic diols, triols, or tetrols.
• the organophosphates of the German application have molecular weights between 200 and 8,000. This German application is primarily directed to low-foaming metalworking lubricating fluids and does not disclose antifreeze formulations.
• European patent application publication No. 59,461 relates to hydraulic fluids containing polyoxyethylene phosphate esters and salts thereof together with a nonionic oxyalkylene block copolymer, said copolymer having a molecular weight from about 950 to about 3500 and having a polyoxypropylene content of 65 to 100 wt. percent based on the weight of the copolymer.
• a further object of this invention provides a stable, clear antifreeze that does not necessarily require the use of silicone-silicate constituents. Yet another and more specific object is to provide an antifreeze having satisfactory protection against aluminum corrosion.
• the present invention relates to an antifreeze composition concentrate for vehicular cooling systems having internal metal surfaces comprising:
• R'O(X) n R" wherein R' and R" are hydrogen or an organic radical having 1 to 24 carbons, and where n is an integer between 1 and 100, wherein X is an alkyleneoxy radical or mixture of alkyleneoxy radicals made from the corresponding monomer or co-monomer and having from two to six carbon atoms, with the proviso that when said oxyalkylene compound has an EO content of less than 50 wt. percent of X, the molecular weight of said compound must be less than 900, and
• the present invention relates to the antifreeze composition produced by diluting the above concentrate with water and/or alcohol.
• the present invention relates to a method of making the above antifreeze composition and composition concentrate.
• the useful compounds may be termed "surface modifiers".
• the function of such compound is to attach or anchor itself to the metal surface and to provide an affinity with the oxyalkylene compound so that a uniform film of the oxyalkylene compound on the surface-modified metal surfaces will be provided.
• the oxyalkylene compound will be sometimes referred to herein as a "pseudo oil”.
• the thus-provided pseudo oil film will serve to protect the coated metal surfaces against corrosion.
• One end of the surface modifier molecule must have the capability of attaching or anchoring the compound to the metal surfaces in the automotive cooling system.
• the moiety selected should possess thermal, hydrolytic and chemical stability in the cooling system environment, viz. - should not be easily stripped from the metal surface.
• the other end of the surface modifier molecule serves to provide affinity between the pseudo oil and the coated metal surface to provide the requisite oil film that imparts the corrosion inhibition characteristic of the antifreeze composition concentrates of this invention.
• This end of the surface modifier molecule typically an organic moiety, should have the capability of being preferentially "wetted" by the pseudo oil rather than by the continuous alcohol-water system of the working antifreeze composition. If this were not the case, formation of the desired uniform pseudo oil film would be impaired.
• the adequacy of the surface modifier in this respect can thus be readily determined by conventional wetting angle measurements and various corrosion measurement techniques.
• the preferred surface modifier compounds are the organophosphates.
• the preferred organophosphates useful in the present invention are those made by reacting phosphoric acids with aliphatic mono-ols, diols, triols or tetrols containing PO/EO, PO/BO or PO/BO/EO with a PO content of at least 50 wt. % based on the weight of the PO+BO+EO in the alcohol reactant. Their mode of synthesis is well-known and is described by L. W. Burnette in Nonionic Surfactants, vol 1, p 372-394 (Marcel Derker, Inc. 1966).
• the term organophosphate is intended to designate any ester of phosphoric or polyphosphoric acid.
• organophosphates useful in the present invention are identified by the structural formula:
• each substituent R 1 , R 2 , and R 3 is selected from the class consisting of the following radicals: hydrogen; alkyl, aryl, alkenyl and alkynyl, with each of the foregoing having up to about 24 carbon atoms; alkyleneoxy, polyalkyleneoxy; phosphate, polyphosphate and their salts, and combinations thereof; with the proviso that at least one of said substituents is an organic radical listed above or combinations thereof.
• the preferred organophosphates have the structural formula identified above wherein at least one R substituent consists of an organic radical containing an alkylene oxide polymer or copolymer R 4 O(PO) x (EO) y (BO) z -, wherein the alkyleneoxide units may be either random or blocked where x > y > z and x + y + z ⁇ about 100, and R 4 is selected from the class of radicals: hydrogen; alkyl, aryl, alkenyl and alkynl with the foregoing having up to about 24 carbon atoms; phosphates, polyphosphates and salts thereof, and combinations of the above.
• These organophosphates preferably have molecular weights below about 10,000 to insure solubility in the antifreeze composition.
• Preferred organophosphates are identified by structural formulae I to III, and the free acids and salts thereof, together with mixtures thereof:
• organophosphates falling within the groups identified by structural formulae I through III above, are identified as follows:
• the amount of the surface modifier employed should be sufficient to provide surface modification of the interior surfaces of the cooling system, viz.- in the working antifreeze, at least a mono-molecular coating of surface modifier on the cooling system metal surfaces is provided, which, in turn allows a pseudo oil film to be formed theron.
• the amount required can be readily determined based on the surface area of the cooling system to be protected. The specific amount can vary over a wide range, but is preferably used in an amount of between 0.001 and about 30 weight percent, more preferably between about 0.005 and about 1, most preferably between about 0.005 and about 0.1, based on the weight of the concentrate. Below the 0.001 weight percent, the amount of organophosphate is expected to be insufficient to be effective, whereas above about 30 percent organophosphate is expected to provide no significant further corrosion inhibition benefits.
• sulfonate such as barium alkyl benzene sulfonate
• a phosponate such as dodecyl phosphonate
• carboxylate such as a carboxylic acid grafted on polyalkylene glycol
• organoammonium salts such as cetyltrimethylammonium chloride, as well as the other hydrophobizers described above, should be present in the broad range of amounts described above for the organophosphates.
• the oxyalkylene compound or "pseudo oil" useful in the antifeeze concentrates and compositions of the present invention preferably provides a cloud point for the antifreeze between about 40°C and about 125°C, more preferably between about 65°C and about 125°C, most preferably between about 65°C and about 90°C.
• This temperature range encompasses the normal operating temperature of vehicular coolants. This cloud point range insures that the antifreeze is visually single-phase when the car's engine is not in operation.
• the antifreeze "consolute", referring to the tendency of the pseudo oil to come out of solution and coat the coolant system metal surfaces at or above the cloud point temperature.
• the preference for utilizing a consolute antifreeze is predicated upon the improved corrosion resistance provided. More particularly, the pseudo oil that comes out of solution is believed to have greater affinity for the surface-modified metal surfaces of the cooling system than does the pseudo oil in solution.
• the use of nonconsolute antifreeze systems will likewise provide improvement in corrosion resistance. Whether the antifreeze is consolute or non-consolute, the pseudo oil employed must be soluble at ambient temperature in the alcohol selected as the antifreeze base.
• the preferred oxyalkylene compounds have a molecular weight of less than about 900 when the EO content of the oxyalkylene portion of the compound is less than about 50 wt. percent. Above a molecular weight of about 900 for oxyalkylene compounds having an EO content less than about 50 wt. percent, these compounds are generally insoluble in aqueous alcohol solutions at room temperature and, hence, not useful as pseudo oils in antifreeze. When the EO content in the oxyalkylene portion of the compounds is more than about 50 wt. percent, the compound is expected to be soluble at room temperature at all molecular weights in alcohol and useful in antifreeze.
• the most preferred oxyalkylene compound is polypropylene glycol.
• the amount of the pseudo oil utilized should be sufficient to provide the desired oil film. Suitable amounts, which will vary over a wide range, can be empirically determined based upon the interior surface area dimensions of the metals to be protected in the automobile cooling system. In order to provide the desired oil film based upon various cooling system sizes, the pseudo oil may accordingly be employed in an amount between about 0.01 and about 5 weight percent, preferably between about 0.1 and 3 weight percent based on the total weight of the concentrate. Below 0.01 weight percent, the oxyalkylene compound would not be expected to be functional, whereas above 5 weight percent, the amount would be too costly.
• the alcohol employed in the composition of this invention preferably is at least one alcohol selected from the group consisting of methanol, ethanol, propanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol.
• other alcohols can be used such as, for example, butylene glycol, the monoacetate of glycerol, the dimethylether of glycerol alkoxyalkanols (such as methoxyethanol), and hydroxy and alkoxy end-blocked polyalkylene oxides.
• the preferred alcohol is ethylene glycol.
• the selection of the pseudo oil should be coordinated with that of the surface modifier.
• the pseudo oil selected should preferentially wet the surface-modified metal surface and essentially displace the alcohol-water medium of the working antifreeze on the surface-modified metal surface.
• a buffer or mixture of buffers is optionally employed in the antifreeze concentrates and compositions of the present invention.
• the buffer can be employed in a wide range of amounts, but is preferably used in an amount of between about 0.1 and about 5 wt. percent based on the weight of the concentrate.
• the borate buffer useful in the composition concentrate of the present invention is conveniently added as the sodium tetraborate pentahydrate salt, which is commercially available. After adding the salt, addition of sodium hydroxide can be used to provide the desired mixture of metaborates and tetraborates in the concentrate.
• phosphates such as alkali metal phosphates
• benzoates and substituted benzoates such as alkali metal hydroxybenzoate
• salts of dibasic acids having 6 to 12 carbons such as sodium sebacate.
• the buffer serves to provide the desired pH and reserve alkalinity (RA) during use.
• the concentrate will have a pH of between about 5.5 and about 11 to provide a diluted antifreeze pH of between about 8 and about 11.
• the working pH selected may affect the adherency of the surface modifier coating on the metal surfaces.
• the efficacy of the particular working pH in this regard may be readily ascertained.
• Optional additives may be employed in minor amounts of less than 50 wt. percent based on the weight of the concentrate.
• Typical optional additives would include, for example, .known corrosion inhibitors for metals such as, for example, molybdates, phosphates, benzoates, sebacates, carbonates, silicone/silicates, hydroxybenzoates or acids thereof, alkali metal nitrates, alkali metal nitrites, tolyltriazole, mercaptobenzothiazole, benzotriazole, and the like, or mixtures thereof. If one or more of the known inhibitors are employed together with the inhibitors of the present invention, the sum total of all inhibitors should be used in an "inhibitory effective amount", i.e., an amount sufficient to provide some corrosion inhibition with respect to the aluminum or other metal surfaces to be protected.
• inhibitors for example, molybdates, phosphates, benzoates, sebacates, carbonates, silicone/silicates, hydroxybenzoates or acids thereof, alkali metal nitrates, alkali metal nitrites, tolyltriazole
• antifreeze concentrate of this invention may be utilized in combination with other antifreeze concentrates.
• the antifreeze concentrates of the present invention may be utilized with state-of-the-art antifreeze compositions.
• United States Patent 3,337,496 is representative of this type of technology.
• the antifreeze concentrates of this invention should afford adequate corrosion resistance in and of themselves.
• the stability and simplicity of the antifreeze concentrates of the present invention should likewise offer processing and handling advantages in comparison to state-of-the-art antifreeze concentrates.
• the following Examples are merely illustrative of, and not intended to limit the present invention.
• This Example illustrates the preparation of several antifreeze concentrates of this invention utilizing various pseudo oils and surface modifiers and tests the effectiveness with respect to heat rejecting aluminum surfaces.
• a base fluid having the composition set forth in Table I, was prepared.
• the antifreeze solution was clear and bright in appearance.
• the apparatus consists of a 1 liter flask, fitted with a condenser, a thermometer, a cold finger, a temperature controller, a 1 1/2 inch diameter x 1/4 inch thick No. 319 aluminum casting alloy (herein “the aluminum disc”), and a soldering iron heat source.
• the apparatus was charged with 900 ml. of the above-diluted test solution and heated to effect boiling at the aluminum disc surface and to maintain a solution temperature of about 80°C.
• the test duration was 168 hours.
• the weight loss of aluminum from the aluminum disc was determined and used as a measure of corrosion inhibitor effectiveness.
• CYCLOPHOS PV-4 a propylene oxide/ethylene oxide based phosphate ester having a PO content of greater than 50% and having a specific gravity of 1.08 at 25°C, a product of Cycle Chemicals, Inc. (hereinafter referred to as "PV-4") .
• ANTARA LE500 a poIyethyIeneoxy-based phosphate ester with aromatic hydrophobe, having a specific gravity of 1.11 at 25°, a product of GAF Corp.
• BASF 7622 an experimental bis-phosphate ester of propylene oxide/ethylene oxide based block copolymer, high in propylene oxide content, a product of BASF Wyandotte Corporation.
• UCON LB65 is a butanoI-started polypropylene glycol having a molecular weight of 300, a product of Union Carbide Corporation.
• UCON 50HB660 is a propylene oxide/ethylene oxide copolymer having 50 wt. percent ethylene oxide based on the total of ethylene oxide plus propylene oxide and having a molecular weight of 1700, product of Union Carbide Corporation.
• CARBOWAX 1000 Is a polyethylene glycol product of Union Carbide having a molecular weight of 1000.
• CARBOWAX 200 is a polyethylene glycol product of Union Carbide, having a molecular weight of 200.
• PROPASOL DM is a monomethyIether of dipropylene glycol product of Union Carbide, having a molecular weight of 148.
• PROPASOL LM is a monomethy Iether of propylene glycol, a product Union Carbide, having a molecular weight of 90.
• PROPYLENE GLYCOL having a molecular weight of 76.
• TERGIT0L NP27 is a nonionic surfactant of Union Carbide comprising a nonyI phenol ethoxylate having an average of 7 ethylene oxide units per molecule, having a molecular weight of 512.
• Table II above generally show each pseudo oil to have some aluminum corrosion inhibition effectiveness as compared to at least one control composition. The results likewise provide guidance for the selection of the more useful combinations of pseudo oil and surface modifier within the broad scope of the present invention.
• the results as presented in Table II above show the effectiveness of a consolute pseudo oil (PPG 725)-containing antifreeze in combination with various surface modifiers in inhibiting aluminum corrosion on the disk test.
• PPG 725 consolute pseudo oil
• a combination of 0.5 weight percent PPG 725 and 0.005 weight percent PV4 produced an aluminum weight loss of zero mg.
• a control with no PPG 725 and no PV4 produced a weight loss of 60 mg.
• a comparison test with no pseudo oil and 0.005 weight percent PV4 produced an aluminum weight loss of 49 mg.
• a comparison test with 0.5 weight percent PPG 725 and no surface modifier produced a weight loss of 29 mg.
• Analogous results to those discussed above were also found when PPG 725 was tested in combination with a higher amount (0.01 weight percent) of PV4, LE500 and BASF 7622.
• PPG 725 exhibited consolute behavior in admixture with the surface modifier and, since the resulting antifreeze had a cloud point between about 40°C and about 75°C, the PPG 725 oil was in a separate phase from that of the rest of the composition at the test temperature.
• certain non-consolute pseudo oils in combination with certain surface modifiers also provided improved results as compared to the control run with no pseudo oil and no surface modifier, and as compared to the respective single component formulations.
• PV4 provided results considered to be excellent in combination with the following non-consolute oils: PPG 425, CARBOWAX 1000, CARBOWAX 200, PROPASOL DM, PROPASOL LM and TERGITOL NP27.
• Example 2 This Example shows the effectiveness of other antifreeze concentrates pursuant to the present invention, employing various surface modifiers.
• LB385. is a butanoI-started polypropylene glycol having a viscosity of about 600 cent!poise at 60°F.
• PLURONIC L8I "carboxylic acid", a carboxylic acid derivative of BASF's PLURONIC L8I.
• PLURONIC L8I is a propylene oxide/ethylene oxide based on the total weight of ethylene oxide plus propylene oxide in the copolymer. The molecular weight of the total propylene oxide in the copolymer is 2250.

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• Preventing Corrosion Or Incrustation Of Metals (AREA)
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• 1985
  • 1985-07-22 WO PCT/US1985/001367 patent/WO1986000918A1/en not_active Application Discontinuation
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