Hydrolytically stable viscosity index improves

a technology of oleaginous fluid and viscosity index, which is applied in the direction of liquid carbonaceous fuels, lubricant compositions, fuels, etc., can solve the problems of imposing severe demands on hydraulic fluids, water or moisture ingress to the system can have a serious effect on the performance of hydraulic fluids, and hydraulic fluids containing acrylic acid ester copolymers have a tendency to form acids, so as to improve hydrolytic stability

Inactive Publication Date: 2006-11-09
DUGGAL AKHILESH +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0003] Additives for improving properties of hydraulic fluids such as viscosity index improving additives are known. Viscosity index improving additives reduce the influence of temperature changes on fluid viscosity. Of the viscosity index improving additives, acrylic acid ester copolymers are particularly suitable for such applications. However, hydraulic fluids containing the acrylic acid ester copolymers have a tendency to form acids in the presence of ambient moisture during use, particularly in high pressure (above 20 MPascals pressure) applications. Accordingly, there exists a need for multi-grade lubricants and hydraulic fluids which are less corrosive under severe operating conditions.
[0005] In another embodiment, there is provided a multi-grade lubricant having improved hydrolytic stability. The lubricant includes an antiwear effective amount of an antiwear agent and an acrylic acid ester copolymer. The acrylic acid ester copolymer includes a reaction product produced by polymerizing more than about 90 weight percent of monomers in a reaction mixture containing a first acrylic acid ester monomer having from about 1 to about 4 carbon atoms, a second acrylic acid ester monomer having from about 12 to about 14 carbon atoms, and a third acrylic acid ester monomer having from about 16 to about 20 carbon atoms, in the presence of a polymerization initiator, a chain transfer agent, and a hydrocracked group II process oil having a sulfur content of less than about 0.03 wt. %. The reaction product as made contains less than about 1 weight percent unreacted monomer.
[0006] An advantage of the embodiments disclosed herein is that fluids, such as hydraulic fluids, containing the improved viscosity index improvers may exhibit increased hydrolytic stability as compared to the same fluids containing conventional viscosity index improvers. Such multi-grade hydraulic fluids may also exhibit improved filterability as compared to conventional multi-grade hydraulic fluids. Without desiring to be bound by theory, it is believed that substantial absence of unreacted monomeric components in the viscosity index improver additive described herein contributes to the improved hydrolytic stability of fluids containing the additive.DETAILED DESCRIPTION OF EMBODIMENT OF THE DISCLOSURE
[0025] The following non-limiting example is provided to illustrate reaction mixtures that may provide acrylic acid ester copolymers that enhance the hydrolytic stability of oleaginous fluids containing them. TABLE 1Example 1Example 2(wt. %)(wt. %)Reaction Mixture ComponentsMethyl methacrylate15.2024.80Lauryl methacrylate43.8849.80Cetyl eicosyl methacrylate15.2714.60Azoisobutyronitrile0.200.25n-dodecyl mercaptan0.450.55Group II hydrocracked diluent oil25.0010.00Copolymer CompositionMethyl methacrylate20.427.8Lauryl methacrylate59.155.8Cetyl eicosyl methacrylate20.516.4
[0027] The disclosure also provides a method for improving the hydrolytic stability and filterability of a multi-grade hydraulic fluid, which comprises adding to the hydraulic fluid from about 1 weight percent to about 20 weight percent, based on the total weight of the hydraulic fluid, of an acrylic acid ester copolymer as described above that is substantially devoid of unreacted monomers.

Problems solved by technology

Hydraulic systems, e.g., systems wherein the operation of high speed, high pressure hydraulic pumps is subject to wide temperature variations, can impose severe demands on hydraulic fluids.
Under such severe operating conditions, water or moisture ingress to the system can have a serious effect on the performance of the hydraulic fluid if reactive acidic components are present in the fluid.
However, hydraulic fluids containing the acrylic acid ester copolymers have a tendency to form acids in the presence of ambient moisture during use, particularly in high pressure (above 20 MPascals pressure) applications.

Method used

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Examples

Experimental program
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Effect test

example 1

[0074] In the following example, an acrylic acid ester copolymer was made in a 10 liter reaction vessel. Hydraulic oils containing the reaction products from Runs 1-4 were tested for hydrolytic stability as described above. The hydraulic oils contained 6.7 weight percent of the reaction product, 0.85 weight percent of HiTEC® 521 antiwear hydraulic package 86.45 weight percent AMERICAS CORE 15ON base oil and 6 weight percent AMERICAS CORE 600N base oil from Exxon Mobil Corporation of Irving, Tex.

TABLE 3Run 1Run 2Run 3Run 4Copolymer PropertiesKinematic viscosity11351162806812at 62.63 wt. %,(cSt at 100° C.)Weight average58,20057,00068,80057,700molecular weight(Mw)Number average33,90032,80040,10032,300molecular weight(Mn)GPC conversion (%)99.0099.9094.6096.10Residual monomer0.420.814.842.32(wt. %)PerformanceCharacteristicsD2619 HydrolyticStabilityCopper weight loss−0.07−0.071.26−0.17(mg / cm2)Acidity of water001.390(mg KOH)Copper appearance1A1A2B1A

[0075] Runs 1 and 2 exhibited lower res...

example 2

[0076] In the next series of runs, copolymers were made in a full scale reaction vessel. As in Example 1, the copolymers were tested in hydraulic oils to determine the hydrolytic stability of the oils containing the copolymers. The copolymers made in Runs 5 and 6 were made with nitrogen sparging. The copolymer of Run 7 was made without nitrogen sparging.

TABLE 4Run 5Run 6Run 7Copolymer PropertiesKinematic viscosity at 62.63 wt.101510831139%, (cSt at 100° C.)Weight average molecular weight54,10055,80063,800(Mw)Number average molecular weight31,00031,00033,500(Mn)GPC conversion (%)98.9098.9097.35Residual monomer (wt. %)0.300.371.33Performance CharacteristicsD2619 Hydrolytic StabilityCopper weight loss (mg / cm2)−0.05−0.06−0.14Acidity of water (mg KOH)000Copper appearance1A1A1A

[0077] As shown by the foregoing examples, runs 1-2, 5-6 provide superior hydrolytic stability to fluids containing the copolymers, provided the monomer content of the copolymers added to the hydraulic oils did no...

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Abstract

An acrylic acid ester polymer having improved characteristics and oleaginous compositions containing the acrylic acid ester polymer. The acrylic acid ester polymer includes a copolymer derived from a first acrylic acid ester monomer having from about 1 to about 4 carbon atoms, a second acrylic acid ester monomer having from about 12 to about 14 carbon atoms, and a third acrylic acid ester monomer having from about 16 to about 20 carbon atoms. The copolymer has a weight average molecular weight ranging from about 20,000 to about 100,000 daltons and contains no more than about 1 weight percent unreacted monomer.

Description

FIELD OF THE DISCLOSURE [0001] The disclosure is directed to hydrolytically stable oleaginous fluids and improved additives for oleaginous fluids, particularly certain poly(alkyl (meth)acrylates) useful as additives for hydraulic fluids. BACKGROUND AND SUMMARY [0002] Hydraulic systems, e.g., systems wherein the operation of high speed, high pressure hydraulic pumps is subject to wide temperature variations, can impose severe demands on hydraulic fluids. Under such severe operating conditions, water or moisture ingress to the system can have a serious effect on the performance of the hydraulic fluid if reactive acidic components are present in the fluid. [0003] Additives for improving properties of hydraulic fluids such as viscosity index improving additives are known. Viscosity index improving additives reduce the influence of temperature changes on fluid viscosity. Of the viscosity index improving additives, acrylic acid ester copolymers are particularly suitable for such applicati...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C10L1/14
CPCC08F220/18C10M145/14C10N2240/08C10N2230/02C10N2230/66C10M2209/084C10N2030/02C10N2030/66C10N2040/08C08F220/1812
Inventor DUGGAL, AKHILESHRYAN, HELEN T.SLAYTON, THERESA L.SHEETS, ROGER M.
Owner DUGGAL AKHILESH
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