A METHOD FOR PROVIDING A FLUID COMPOSITION WITH IMPROVED FIRE RESISTANCE

Abstract: The present invention provides a method for providing an anhydrous poly(alkylene glycol)-based fluid composition with Group 1 or Group 2 fire resistance properties. According to the method, the fluid composition is formulated with an ethylene oxide/alkylene oxide wt. percent ratio and/or an amount of antioxidant sufficient to provide the fluid composition with a spray flammability parameter of less than 8.0 x 10<4>. Fluid compositions formulated according to the invention are useful as hydraulic fluids and quenchants and in other industrial and commercial applications requiring fluids having enhanced fire resistance.

Description: A METHOD FOR PROVIDING A FLUID COMPOSITION WITH IMPROVED FIRE RESISTANCE The present invention relates to a method for providing fluids with improved fire resistance properties. More particularly, the invention provides a method for providing anhydrous poly(alkylene-glycol)-based fluid compositions with Group 1 or Group 2 fire resistance properties, as measured by calculating a spray flammability parameter which is representative of the heat content of a fluid. Until recently, fire resistant fluids have typically been classified using either a spray flammability test or a hot-channel test. However, those skilled in the art have long recognized that these testing protocols do not adequately discriminate between observable and significant differences in the fire resistance properties of various fluid types. Accordingly, Factory Mutual Research Corporation of Norwood, MA (Factory Mutual) has developed a new testing protocol based on the heat content of a fluid as represented by an experimentally determined spray flammability parameter (S.F.P.). This new S.F.P. protocol provides a quantitative measure of the fire resistance properties of different fluids and allows for accurate differentiation among fluid types. Factory Mutual is recognized by those skilled in the art as a highly authoritative resource for determining the fire resistance properties of various materials, and the S.F.P. protocol is expected to be the standard by which fire resistant fluids will be categorized. According to the new protocol, an experimental S.F.P. parameter is calculated by the following equation from experimental data: Equation I S.F.P. = (1.47 x l0 17 ft ) (Pf) x (T f ) 4 x (m f ) where: Q C h = Chemical heat release of spray flame (kilowatts) pf = Fluid density (kilograms per cubic meter) T f = Fire point temperature (degrees Kelvin) irif = Mass flow rate of the fluid (grams per second). The S.F.P. may also be estimated according to the following equation which assumes 100 percent combustion efficiency: Equation II S.F.P. = (1.47 x l0 17 x (Α Hτ) (Pf) x (Tf) 4 where: Δ H T = The net heat of complete combustion (kilojoules per gram) Using the S.F.P. protocol, fluids are classified into one of the following groups as set forth in Table 1 : Table 1 Classification of Fluids Calculation of the estimated S.F.P. is used as a preliminary screening procedure for fire resistance. For example, if the objective is to determine if a fluid is Group 1 or Group 2, and if an S.F.P. value of significantly less than 4.0 x 10 4 is obtained, then the fluid will be certified as Group 1 by Factory Mutual without further testing. However, if the estimated S.F.P. is close to 4.0 x 10 4 then the fluid must be tested experimentally to accurately classify it in the appropriate category. A similar procedure is used to classify a fluid according to Groups 2 or Group 3 The present invention provides a method for providing an anhydrous poly(alkylene-glycol)- based fluid composition with at least Group 2 fire resistance properties. According to the invention, the composition is formulated with an ethylene oxide/alkylene oxide weight percent ratio and/or an amount of antioxidant sufficient to provide the fluid composition with a spray flammability parameter of less than 8.0 x 10 4 . More specifically, the invention provides a method for providing an anhydrous poly(alkylene-glycol)-based fluid composition with at least Group 2 fire resistance, characterized by the step of: formulating the composition with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the fluid composition with a spray flammability parameter of less than 8.0 x 10 4 . The invention further provides a method for providing a hydraulic system with at least Group 2 fire resistant properties, characterized by the step of: adding to the system an anhydrous poly(alkylene-glycol)-based hydraulic fluid formulated with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the fluid with a spray flammability parameter of less than 8.0 x lO 4 The invention further provides a method for providing a heat treatment system for metal working with at least Group 2 fire resistant properties characterized by the step of: adding to the system an anhydrous poly(alkylene-glycol)-based quenchant formulated with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the quenchant with a spray flammability parameter of less than 8.0 x lO 4 . Anhydrous poly(alkylene-glycol)-based fluid compositions comprise polymers of poly(alkylene-glycols) (PAG's) which are made from the reaction of alkylene oxide monomers and a nucleophilic starter, usually an alcohol. These polymers are represented by the following general formula: R' R" where: Z = an alcohol starter with 1-20 carbon atoms, including methanol, ethanol, propanol, isopropanol, butanol, glycerine, and sucrose. Z may also be an amine starter such as ammonia, monoethanolamine, triethanolamine, and diethanolamine; R', R" = H, CH 3 , any aryl or C 2 -C 16 alkyl group in any combination resulting in a block or random structure; R"'= H, CH 3 , any aryl, ester, or C 2 -C 16 alkyl group; n = 5-500; and x = 1-6 While any PAG-polymer having this general formula may be used in formulating fluid compositions in accordance with the present invention, these fluid compositions are usually formulated using ethylene oxide and/or alkylene oxide polymers. The ethylene oxide can range from 0 to 100 weight percent of the oxide feed, with the balance being the alkylene oxide monomer(s), typically propylene oxide, although other oxides such as butylene oxide or styrene oxide can also be used. As noted above, the sequencing of the oxide monomers can be either random or block. In accordance with the present invention, fluid compositions are provided with at least Group 2 fire resistance by providing the composition with an ethylene oxide/alkylene oxide weight percent ratio of from 0:1 to 1:0. In those formulations which include antioxidant, the composition includes at least 0.1 weight percent antioxidant, preferably from 0.5 to 10 weight percent antioxidant, and most preferably from 1 to 2 weight percent antioxidant. Preferably, the fluid composition is provided with Group 1 fire resistance, that is, with an ethylene oxide/alkylene oxide weight percent ratio and/or an amount of antioxidant sufficient to provide a spray flammability parameter of less than or equal to 4.0 x 10 . In one embodiment, this is accomplished by formulating the composition with an ethylene oxide/propylene oxide ratio of at least 2:1 to 1:0. In a second embodiment, Group 1 fire resistance is provided by formulating the composition with an ethylene oxide/propylene oxide weight percent ratio of from 1 :3 to 3:1 and with 1 weight percent to 2 weight percent of antioxidant. In yet another embodiment, borderline Group 1 /Group 2 fire resistance is provided by formulating the composition with an ethylene oxide/propylene oxide weight percent ratio of 0:1 and from 1 to 2 weight percent of antioxidant. Fluids formulated according to the method of the invention can be used in a number of industrial and commercial applications where the risk of fire is a critical concern. For example, hydraulic system failures have, in a number of instances, resulted in serious fires accompanied by loss of life. Accordingly, hydraulic fluids must not only have superior high pressure and lubricating properties, but these fluids must also provide fire resistance in those applications where a significant risk of fire would result from an hydraulic system failure. Quenchant fluids used in heat treating systems for metalworking applications also present a significant risk of fire. This is particularly the case with marquenching fluids, which are used for the high-temperature heat treatment of crack-sensitive steel alloys. Anhydrous poly(alkylene-glycol)-based fluid compositions formulated according to the invention are particularly suitable for use as hydraulic fluids. These compositions not only provide superior high pressure and fire resistant properties, but can also provide superior lubrication. In addition, it is possible to formulate fire resistant anhydrous (PAG-based hydraulic fluids which also exhibit good biodegradabihty and low aquatic toxicity. The fluid compositions taught by the invention are also excellent quenchants and are therefore particularly suitable for use in heat treating applications. These compositions have quenching properties equivalent to those of the specially formulated mineral oil quenchants typically used in the art and provide the important advantage of being fire resistant. The compositions can also formulated to be water soluble or biodegradable and to provide significantly lower sludging tendencies as compared to mineral oil quenchants. Fluid compositions formulated in accordance with the invention may also include additional components depending on the particular industrial or commercial application for which the fluid will be used. Accordingly, these compositions may include, for example, lubricity modifiers, corrosion inhibitors (both ferrous and non-ferrous types), anti-wear agents, extreme-pressure modifiers, dyes, biocides, anti-foaming agents, wetting agents, viscosity modifiers, thermal stability agents and detergents. It has been determined that the ethylene oxide/alkylene oxide content of an anhydrous poly(alkylene-glycol) (PAG)-based fluid composition significantly impacts the fire resistance properties of the composition. More specifically, it has been discovered that by increasing the ethylene oxide content of an anhydrous PAG-based fluid composition, the S.F.P. of the composition is lowered. It has also been discovered that the addition of one or more antioxidants to an anhydrous PAG-based fluid composition reduces the S.F.P. of the composition, regardless of the ethylene oxide/alkylene oxide weight percent ratio of the composition. The S.F.P. lowering effect provided by the antioxidant is dependent on the structure of the antioxidant and its concentration in the fluid composition, at least up to a certain concentration level. As noted previously, one or more antioxidants may be used to provide the desired level of fire resistance. In order to determine the effects of ethylene oxide/alkylene oxide weight percent ratio and antioxidant selection and concentration on enhancing the fire resistant properties of anhydrous PAG-based fluid compositions, the S.F.P. was estimated for several fluid compositions using Equation II above. The fluid compositions selected for study and the data obtained for these fluids are summarized below in Table 2 as Examples 1-15. Each fluid composition consists of a base fluid having a specified ethylene oxide/propylene oxide (EQ/PO) weight percent ratio, or such a base fluid together with an antioxidant. It should be understood that while each of the fluid compositions used in Examples 1-15 includes either ethylene oxide or propylene oxide polymers or ethylene oxide/propylene oxide copolymers, the invention is in no way limited in this regard, and similar results can be expected with other poly(alkylene-glycols) having the general formula set forth above. Table 2 I I Table 2 Con't... Table 2 Con't.. 1 I Table 2 Con't. 1 The fire point was determined according to A.S.T.M. D92. 2 Heat of combustion was determined according to A.S.T.M D240. This base fluid also includes Ortholeum 535 (0.25 wt. % of base fluid) and Tolytriazole (0.01 wt. % of base fluid). UCON Lubricant LB-285 is an alcohol-started polymer of propylene oxide having a viscosity of 285 Saybolt Universal Seconds (SUS) at 38 ° C. This polymer is available from Union Carbide Corporation, Danbury, CT. UCON Lubricant LB- 165 is an alcohol-started polymer of propylene oxide having a viscosity of 165 SUS at 38 C. This polymer is available from Union Carbide Corporation, Danbury, CT. UCON Lubricant 50-HP-260 is an alcohol-started copolymer containing equal amounts by weight of ethylene oxide and propylene oxide. The copolymer has a viscosity of 260 SUS at 38 C and is available from Union Carbide Corporation, Danbury, CT. CARBO WAX TPEG-990 is a glycerin-started polymer of ethylene oxide which has a molecular weight of 990 grams per mole. CARBOWAX TPEG-990 is available from Union Carbide Corporation, Danbury, CT. The data presented in Table 2 show that increasing the ethylene oxide content of an anhydrous PAG-based fluid composition enhances the fire resistance properties of the fluid. In particular, note that Examples 15, which contains 100 weight percent of ethylene oxide and which does not include an antioxidant, has an S.F.P. of 3.02 x 10 . Accordingly, this PAG-based fluid composition exhibits Group 1 fire resistance properties. Example 2 also does not include an antioxidant and has an ethylene oxide/propylene oxide weight percent ratio of 1:1. Example 2 has an S.F.P. of 4.71 x 10 4 and is therefore classified only as a Group 2 fire resistant fluid. However, the S.F.P. of the Example 2 composition is significantly lower than that of the Example 3 composition which is 100 weight percent propylene oxide. Those skilled in the art have not heretofore appreciated that Group 1 and Group 2 fire resistance can be provided in an anhydrous PAG-based fluid composition solely by controlling the ethylene oxide to alkylene oxide weight percent ratio of the fluid. These fluids have been used in the past as hydraulic fluids; however, fire resistance was achieved either by incorporating water in the fluid or by adding an agent which controls the droplet size of the fluid, as disclosed in U.S. Patent No. 5,141,663. Incorporating water in an hydraulic fluid presents several disadvantages. These fluids generally exhibit inferior hydraulic pump performance as compared to anhydrous fluids, and they exhibit poor lubrication protection and a much greater potential for cavitation. The anhydrous PAG-based fluid disclosed in the '663 patent overcomes these disadvantages. However, as noted above, the composition requires the addition of an agent to control the droplet size of the fluid. Only by employing such an agent can the droplet size and distribution of the fluid as it is sprayed from a nozzle be controlled to provide acceptable fire resistance. Quenchants including water soluble polymers are known in the art. However, these quenchants are often characterized by excessive cooling rates sufficient to causes cracking of steel. Moreover, vaporization of the water in these quenchants can contaminate heat treating atmospheres. The use of anhydrous fluid compositions eliminates these potentially severe problems. Anhydrous PAG-based fluid compositions containing 100 weight percent of ethylene oxide have been used in the past as quenchants on a very limited basis. However, neither the superior fire resistance properties of these fluids nor the fact that fire resistance could be provided by controlling the ethylene oxide content of the fluid was appreciated by those skilled in the art. The present invention does not require the addition of water or the use of an agent to control droplet size. As shown in Table 2, Group 1 or Group 2 fire resistance is achieved by providing a sufficiently favorable ethylene oxide to propylene oxide weight percent ratio. More specifically, Group 1 fire resistance is achieved by providing an anhydrous PAG- based fluid with an ethylene oxide/propylene oxide weight percent ratio of at least 2:1. Anhydrous PAG-based fluid compositions having an ethylene oxide/propylene oxide weight percent ratio of at least 1:1 exhibit Group 2 fire resistance. The data in Table 2 also demonstrate that the fire resistance properties of an anhydrous PAG-based fluid composition are enhanced by the addition of one or more antioxidants, regardless of the ethylene oxide/propylene oxide weight percent ratio of the composition. Moreover, the data show that the addition of antioxidant to an anhydrous PAG-based fluid composition provides Group 2 fire resistance even where the composition contains 100 wt. percent of propylene oxide. In particular, the results shown for Examples 3, 5-8 and 10 demonstrate that fire resistant properties approaching very close to Group 1 fire resistance can be provided by the addition of a sufficient amount of an appropriate antioxidant or combination of antioxidants. Antioxidant structure plays an important role in the S.F.P. lowering effect. Several classes of antioxidants have been found to be particularly effective in improving the fire resistant properties of PAG-based fluids. The preferred antioxidants include, phenolic antioxidants, phenol formaldehyde resins containing bisphenol A as a termonomer, amine-based antioxidants such as phenyl-α-napthylamine (PANA), phenothiazine, and mixtures of these antioxidants. It should be understood, however, that the invention is not limited to these antioxidants and that other antioxidants known in the art may also be employed. For example, phosphite functional antioxidants such as triphenyl phosphite may be employed; however, the S.F.P lowering effect of these antioxidants are generally inferior to the effect provided by the preferred antioxidants noted above. Examples 3, 5-8 and 10 demonstrate the effect of antioxidant structure on S.F.P. reduction. All of these examples employ the same anhydrous PAG-based fluid containing 100 wt. percent of propylene glycol. The data show that phenothiazine was the most effective antioxidant evaluated in the study (Example 7). PANA, an amine-based antioxidant, and IRGANOX E-3201, a phenolic-based antioxidant available from Ciba Specialties Chemicals Corporation, Tarrytown, NY were both equally effective in reducing the S.F.P. of the base fluid (Examples 5 and 13). Triphenyl phosphite (Example 10) was the least effective of the antioxidants examined. Other effective antioxidants include IRGANOX L-06 and IRGANOX 1010, both of which are amine-based antioxidants available from Ciba Specialties Chemicals Corporation, Tarrytown, NY. With respect to antioxidant concentration, the results in Table 2 indicate that the S.F.P. lowering effect provided by the antioxidant is apparent only up to a certain concentration of antioxidant in the fluid composition. Additional levels of antioxidant provide only a marginal improvement in the fire resistance properties of the composition. Note, in particular, that Examples 3-5 all comprise the same anhydrous PAG-based fluid but contain varying amounts of the antioxidant N-phenyl alpha naphthylamine (PANA). Examples 4 and 5 have considerably lower S.F.P. as compared to Example 3, which does not contain any antioxidant. However, doubling the antioxidant concentration from 1 wt. percent in Example 4 to 2 wt. percent in Example 5 provides only a marginal improvement in fire resistance. Generally, the fire resistance provided by the antioxidant increases as the ethylene oxide content of the fluid composition increases. Thus, the lowest S.F.P. results were obtained with PAG-based compositions containing 100 wt. percent ethylene oxide together with an antioxidant, as shown by Example 11. Slightly higher S.F.P.'s, but still Group 1 fire resistance, was provided by the use of an antioxidant in a fluid composition containing only 50 wt. percent ethylene oxide. In cases where the anhydrous PAG-based fluid composition does not contain any ethylene oxide, at least 2 wt. percent of antioxidant is preferred. Where the fluid composition is characterized by an ethylene oxide/propylene oxide wt. percent ratio of from 1 :3 to 3:1, the composition preferably includes from 1 wt. percent to 2 wt. percent of the antioxidant. As discussed above, the S.F.P. in each of Examples 1-15 was estimated using Equation II, which assumes 100 percent combustion. Accordingly, the S.F.P. for several of the fluid compositions set forth in Table 2 (Examples 3-10) was derived experimentally to determine how closely the estimated S.F.P. values and the experimental S.F.P. values agreed. The results of this study are set forth below in Table 3. Table 3 As shown in Table 3, the estimated S.F.P. values are close but always higher than the experimentally derived S.F.P. values. This is as expected, since Equation II assumes 100 percent combustion. The results confirm that Equation II may be used to provide a estimated S.F.P. that closely approximates the experimentally derived value. As discussed previously, anhydrous PAG-based fluid compositions prepared according to the method of the invention may be used as fire resistant hydraulic fluids, quenchants and lubricating fluids. However, those skilled in the art will appreciate that the invention is in no way limited by these particular applications and that fluids prepared by the method taught by the invention may be used in a wide variety of industrial and commercial applications where fluid compositions having Group 1 or Group 2 fire resistance are required.

Claims: WE CLAIM: 1. A method for providing an anhydrous poly(alkylene-glycol)-based fluid composition with at least Group 2 fire resistance, characterized by the step of: formulating the composition with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the fluid composition with a spray flammability parameter of less than 8.0 x 10 4 . 2. The method of claim 1 , wherein the alkylene oxide is propylene oxide, butylene oxide, or styrene oxide. 3. The method of claim 1 , wherein the ethylene oxide/alkylene oxide weight percent ratio is at least 1:1. 4. The method of claim 3, wherein the ethylene oxide/alkylene oxide ratio is at least 2:1. 5. The method of claim 1 , wherein the fluid composition comprises at least 0.1 weight percent antioxidant. 6. The method of claim 5, wherein the fluid composition comprises from 0.5 to 10 weight percent antioxidant. 7. The method of claim 6, wherein the fluid composition comprises from 1 to 2 weight percent of antioxidant. 8. The method of claim 1 , wherein the fluid composition consists essentially of 100 weight percent ethylene oxide. 9. The method of claim 1 , wherein the fluid composition consists essentially of ethylene oxide and antioxidant. 10. The method of claim 1, wherein the ethylene oxide/alkylene oxide weight percent ratio is 3:1. 11. The method of claim 1 , wherein the ethylene oxide/alkylene oxide weight percent ratio is from 1:3 to 3:1 and the fluid composition comprises from 1 weight percent to 2 weight percent of antioxidant. 12. The method of claim 2, wherein the alkylene oxide is propylene oxide and the composition has an ethylene oxide/propylene oxide ratio of 0: 1 , and wherein the composition includes from 1 to 2 weight percent of antioxidant. 13. The method of claim 1 , wherein the antioxidant is amine-based antioxidants, phenolic antioxidants, phenol formaldehyde resins containing bisphenol A as a termonomer, phosphite functional antioxidants, or mixtures thereof. 14. A method for providing a hydraulic system with at least Group 2 fire resistant properties, characterized by the step of: adding to the system an anhydrous poly(alkylene-glycol)-based hydraulic fluid formulated with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the fluid with a spray flammability parameter of less than 8.0 x lO 4 . 15. A method for providing a heat treatment system for metal working with at least Group 2 fire resistant properties characterized by the step of: adding to the system an anhydrous poly(alkylene-glycol)-based quenchant formulated with at least one of an ethylene oxide/alkylene oxide weight percent ratio and an amount of antioxidant sufficient to provide the quenchant with a spray flammability parameter of less than 8.0 x 10 4 .

Inventors: BROWN WILLIAM LOWELL, MATLOCK PAUL LUMPKIN, TOTTEN GEORGE EDWARD, BROWN, WILLIAM, LOWELL, MATLOCK, PAUL, LUMPKIN, TOTTEN, GEORGE, EDWARD
Applicants: UNION CARBIDE CHEM PLASTIC, UNION CARBIDE CHEMICALS & PLASTICS TECHNOLOGY CORPORATION
Application year: 2001
Main classification: C08K5
IPC codes: C08K5, C08L71, C09K21, C10M107, C10M129, C10M133, C10M137, C10M145, C10M169, C10N30, C10N40, C23F11