GB2245587A

GB2245587A - Heat transfer device lubricant

Info

Publication number: GB2245587A
Application number: GB9109967A
Authority: GB
Inventors: Stuart Corr; Richard Llewellyn Powell
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1990-05-10
Filing date: 1991-05-09
Publication date: 1992-01-08
Also published as: GB9109967D0; GB9010517D0

Abstract

Lubricant composition comprising a hydrofluoroalkane or hydrochlorofluoroalkane working fluid and a fluorinated ether or ester such as octafluoropentylundecyl-tricarballylate or hexadecafluorononyl (3-methyl glutarate).

Description

LUBRICANTS This invention relates to lubricants and more particularly to their use in heat transfer devices.

Heat transfer devices of the mechanical vapour recompression type, including refrigerators, heat pumps and air conditioning systems, are well known. In such devices, a working fluid of suitable boiling point evaporates at low pressure taking heat from the surrounding zone. The resulting vapour is then compressed and passed to a condenser where it condenses and gives off heat to a second zone. The condensate is then returned through an expansion valve to the evaporator, so completing the cycle. The mechanical energy required for compressing the vapour and pumping the fluid is provided by, for example, an electric motor or an internal combustion engine.

The working fluids used in these heat transfer devices include chlorofluorocarbons such as dichlorodifluoromethane (R-12) the production of which is likely to be severely limited by international agreement in order to protect the stratospheric ozone layer. As is the case with other mechanical equipment, it is necessary for the moving parts of the heat transfer devices to be adequately lubricated and the devices are generally designed to use lubricants which are miscible with the working fluids, mineral oil commonly being used in conjunction with dichlorodifluoromethane.

Unfortunately some of the compounds, for example 1,1,1,2-tetrafluoroethane (R-134a), which have been proposed as working fluids to replace dichlorodifluoromethane are insufficiently soluble in mineral oils to allow the latter to be used as lubricants. Polyalkylene glycols have been proposed as alternatives but they are not entirely satisfactory for a number of reasons. Thus, whilst they show reverse solubility such that the working fluid tends to separate from the lubricant at temperatures above about 400C, they often attract water to an extent sufficient to cause corrosion in the equipment.

Furthermore, they often fail to wet metals sufficiently to provide efficient lubrication and have an adverse effect on aluminium commonly used for the construction of compressors.

It has now been found that certain ethers and esters as hereinafter defined are excellent lubricants having adequate miscibility with 1,1,1,2-tetrafluoroethane and some related hydrofluorocarbon working fluids such as 1,1,2,2-tetrafluoroethane, and hydrochlorofluorocarbons such as the monochlorotetrafluoroethanes and are free from the disadvantages associated with polyalkylene glycols or esters having other structures. In particular, the ethers defined below are characterised by a high degree of thermal stability ensuring an extended useful life for the lubricant and minimal formation of resins or carbon deposits when the compressors are operated at high temperatures.

Accordingly, the invention provides a composition for use in a compression type heat transfer device comprising: a) a hydrofluoroalkane or hydrochlorofluoro- alkane working fluid, and b) a sufficient amount to provide lubrication of a compound of the formula: (A) Rf1(Ar)x-CH2Q wherein Q represents -OR or -NR2 or a residue Z of an acid wherein R is a polyoxyalkylene radical, Ar is an optionally substituted arylene radical, x is 0 or 1 and Rfl is a fluorinated radical selected from

wherein a is 0-20, preferably 0-16, (ii) CF3(CF2)bCH2wherein y is 0-13, preferably 0-9, (iii) H(CF2CF2) wherein c is 1-4, (iv) CF3(CF2)dCFHCF2wherein d is 0-10, preferably 0-6, (v) CF3(CF2)ewherein e is 0-12, preferably 0-7, (vi) (CF3)2CFO(CF2CF2)f(CH2)g- wherein f is 0-4, preferably 0-2 and g is 0 or 1, and

wherein h is 0 or 1;

wherein Q is as defined above, R1 is a C1-20, preferably C1-6 alkyl radical and Rf2 is a fluorinated radical selected from: (i) H(CF2CF2)c wherein c is as defined above, (ii) CF3(CF2)dCFHCF2wherein d is as defined above, (iii) CF3(CF2)ewherein e is as defined above, and (iv) (CF3)2CFo(CF2CF2)i- wherein i is 0-4, preferably 0-2; (C) R20(CH2)k(CF2CF2)j(CH2)k0R21 wherein j is 1-6, preferably 1-4, k is 1-4 and R2 is hydrogen, alkyl having 1-20, preferably 1-6, carbon atoms, polyoxyalkylene or a fluorinated radical of the formula::

wherein Rf3 is Rfl as defined above or (CF3)2CFO(CF2CF2)iwherein i is 0-4, preferably 0-2, R1 is as defined above, and R21 is the same as R2 or a residue Z of an acid, (D) Rf40ArOR wherein Rf4 is a perfluoroalkenyl radical having 6-12 carbon atoms, R is as defined above and Ar is an optionally substituted arylene radical, (E) Rf4OAr1(OR)2 wherein Rf4 and R are as defined above and Arl is an optionally substituted trivalent aromatic radical, (F) Rf4OArCONR3(CH2)w OR wherein Rf4, R and Ar are as defined above, R3 is a C1-4 alkyl group and w is 2-6, (G) Rf4OArCON [ (CH2)w OR]2 wherein Rf4, R, Ar and w are as defined above, (H) Rf4OArSO2NR3(CH2)w OR wherein Rf4, R, Ar, R3 and w are as defined above, (I) Rf40ArS02N [ (CH2)w OR ] 2 wherein Rf4, R, Ar and w are as defined above, (J) Rf5(OArOR)2 wherein Rf5 is a perfluoroalkenylene radical having 6-12 carbon atoms and Ar and R are as defined above, (K) Rf5 [ OAr1(OR)2 ] 2 wherein Rf5, R and Arl are as defined above,

wherein R is as defined above,

wherein R is as defined above, (N) X-(0R41)n (OZ)m#n wherein m is 1-8, m-n is 1-8, R41 is hydrogen or C1-6 alkyl, Z is a residue of an acid, and X is a fluorine-free organic residue having a molecular weight of from 15 to 5000, especially a hydrocarbon residue optionally containing one or more ether link;; (O) Ethers obtained by grafting fluoro-olefins, for example tetrafluoroethylene or hexafluoropropylene, to alkylphenols, polyoxyalkylene polyols or end-capped polyoxyalkylene polyols, (P) fluorinated alkylene oxide polymers,

wherein R4 is C8H15 or C1,20-alkyl and each of x and y, independently, is 0-25, the sum of x and y being at least 5,

wherein R4, x and y are as defined above (S) Rf40ArR5 wherein Rf4 and Ar are as defined above and R5 is C6#30-alkyl, (T) Rf5(OArR5)2 wherein Rf5, Ar and R5 are as defined above.

and wherein Z is the residue of an acid selected from compounds of the formula: (1) Rf1- (Ar)x-COOH wherein Rfl, Ar and x are as defined above, (2) Rf40ArCOOH wherein Rf4 and Ar are as defined above, (3) Rf40ArS020H wherein Rf4 and Ar are as defined above, (4) Rf4OAr1(COOH)2 wherein Rf4 and Arl are as defined above, (5) Rf5(OArCOOH)2 wherein R5f and Ar are as defined above, (6) Rf5(OArSO2OH)2 wherein Rf5 and Ar are as defined above, (7) Rf5#OAr1(CO0H)2 ] 2 wherein Rf5 and Arl are as defined above,

(9) C6F13CH2ArSO2OH wherein Ar is as defined above, (10) Y-(COOH)n wherein n is 1-4 and Y is a fluorine-free organic residue having a molecular weight of from 15 to 5000, especially a hydrocarbon residue optionally containing one or more ether link.

According to another aspect of the invention there is provided a composition for use in a compression type heat transfer device comprising: a) a hydrofluoroalkane or hydrochlorofluoro- alkane working fluid, and b) a sufficient amount to provide lubrication of an ether selected from compounds of the formula:: (A) Rf1(Ar)x-CH2Q wherein Q represents -OR or -NR2 wherein R is a polyoxyalkylene radical, Ar is an optionally substituted arylene radical, x is O or 1 and Rfl is a fluorinated radical selected from

wherein a is 0-20, preferably 0-16, (ii) CF3(CF2)bCH2wherein y is 0-13, preferably 0-9, (iii) H(CF2OF2)c- wherein c is 1-4, (iv) CF3(CF2)dCFHCF2wherein d is 0-10, preferably 0-6, (v) CF3(CF2)e- wherein e is 0-12, preferably 0-7, (vi) (CF3)2CFO(CF2CF2)f(CH2)g- wherein f is 0-4, preferably 0-2 and g is O or 1, and

wherein h is O or 1;

wherein Q is as defined above, R1 is a C1-20, preferably C1-6 alkyl radical and Rf2 is a fluorinated radical selected from:: (i) H(CF2CF2)c wherein c is as defined above, (ii) CF3(CF2)dCFHCF2wherein d is as defined above, (iii) CF3(CF2)e- wherein e is as defined above, and (iv) (CF3)2CFO(CF2CF2)i wherein i is 0-4, preferably 0-2; (C) R20(CH2)k(CF2CF2)j(CH2)kOR2 wherein j is 1-6, preferably 1-4, k is 1-4 and R2 is hydrogen, alkyl having 1-20, preferably 1-6, carbon atoms, polyoxyalkylene or a fluorinated radical of the formula::

wherein Rf3 is Rfl as defined above or (CF3)2CFO(CF2CF2)iwherein i is 0-4, preferably 0-2, and R1 is as defined above, (D) Rf40ArOR wherein Rf4 is a perfluoroalkenyl radical having 6-12 carbon atoms, R is as defined above and Ar is an optionally substituted arylene radical, (E) Rf40Ar1(OR)2 wherein Rf4 and R are as defined above and Arl is an optionally substituted trivalent aromatic radical, (F) Rf4OArCONR3(CH2)w OR wherein Rf4, R and Ar are as defined above, R3 is a C1-4 alkyl group and w is 2-6, (G) Rf40ArCON [ (CH2)w OR ] 2 wherein Rf4, R, Ar and w are as defined above, (H) Rf4OArSO2NR3(CH2)w OR wherein Rf4, R, Ar, R3 and w are as defined above, (I) Rf4oArso2N [ (cH2)w OR ] 2 wherein Rf4, R, Ar and w are as defined above, (J) Rf5(OArOR)2 wherein Rf5 is a perfluoroalkenylene radical having 6-12 carbon atoms and Ar and R are as defined above, (K) Rf5 [ OAr1(OR)2 ] 2 wherein Rf5, R and Arl are as defined above,

wherein R is as defined above,

wherein R is as defined above, (N) Ethers obtained by grafting fluoro-olefins, for example tetrafluoroethylene or hexafluoropropylene, to alkylphenols, polyoxyalkylene polyols or end-capped polyoxyalkylene polyols, (0) fluorinated alkylene oxide polymers,

wherein R4, x and y are as defined above (R) Rf40ArR5 wherein Rf4 and Ar are as defined above and R5 is C6#30-a1kyl, (S) Rf5(OArR5)2 wherein Rf5, Ar and R5 are as defined above.

According to a further aspect of the invention there is provided a composition for use in a compression type heat transfer device comprising: a) a hydrofluoroalkane or hydrochlorofluoro- alkane working fluid, and b) a sufficient amount to provide lubrication of an ester obtainable by reaction between a hydroxy compound selected from compounds of the formula: (A) Rfl(Ar)x-CH2OH wherein Ar is an optionally substituted arylene radical, x is O or 1 and Rfl is a fluorinated radical selected from::

wherein a is 0-20, preferably 0-16, (ii) CF3(CF2)b CH2wherein b is 0-13, preferably 0-9, (iii) H(CF2CF2) wherein c is 1-4, (iv) CF3(CF2)d CFHCF2wherein d is 0-10, preferably 0-6, (v) CF3(CF2)ewherein e is 0-12, preferably 0-7, (vi) (CF3)2CFO(CF2CF2)f (CF2)gwherein f is 0-4, preferably 0-2 and g is 0 or 1, and

wherein h is O or 1;

wherein R1 is a Cl#20, preferably C1-6 alkyl radical and Rf2 is fluorinated radical selected from:: (i) H(CF2CF2)c- wherein c is as defined above, (ii) CF3(CF2)d CFHCF2wherein d is as defined above, (iii) CF3(CF2)ewherein e is as defined above, and (iv) (CF3)2CFO(CF2CF2)i wherein i is 0-4, preferably 0-2; (C) R20(CH2)k(CF2CF2)j(CH2)kOH wherein j is 1-6, preferably 1-4, k is 1-4 and R2 is hydrogen, alkyl having 1-20, preferably 1-6, carbon atoms, polyoxyalkylene or a fluorinated radical of the formula::

wherein Rf3 is Rfl as defined above or CCF3)2CFO(CF2CF2)i- wherein i is 0-4, preferably 0-2, and R1 is as defined above (D) Rf4ArOH wherein Rf4 is a perfluoroalkenyl radical having 6-12 carbon atoms and Ar is an optionally substituted arylene radical, (E) Rf40Arl(OH)2 wherein Rf4 is as defined above and Arl is an optionally susbtituted trivalent aromatic radical, (F) Rf4 OArC0NR3CCH2)wOH wherein Rf4 and Ar are as defined above, R3 is a C1-4 alkyl group and w is 2-6, (G) Rf4 OArCON [ CH2)wOH ] 2 wherein Rf4, Ar and w are as defined above, (H) Rf4 0ArSO2NR3CCH2)wOH wherein Rf4, Ar, R3 and w are as defined above, (I) Rf4 0 ArSO2N [ (CH2)wOH ] 2 wherein Rf4, Ar and w are as defined above, (J) Rf5 (OArOH)2 wherein Rf5 is a perfluoroalkenylene radical having 6-12 carbon atoms and Ar is as defined above, (K) Rf5 [ OAr1(0H)2 ] 2 wherein Rf5 and Arl are as defined above,

(N) X-(OR4)m wherein m is 1-8, R4 is hydrogen or C1-6 alkyl, at least one R4 being hydrogen, and X is a fluorine-free organic residue having a molecular weight of from 15 to 5000, especially a hydrocarbon residue optionally containing one or more ether link; and an acid selected from compounds of the formula:: (1) Rf1-(Ar)x-OOOH wherein Rfl, Ar and x are as defined above, (2) Rf4OArCOOH wherein Rf4 and Ar are as defined above, (3) Rf4OArSO20H wherein Rf4 and Ar are as defined above, (4) Rf40Arl(COOH)2 wherein Rf4 and Arl are as defined above, (5) Rf5(0ArCOOH)2 wherein Rf5 and Ar are as defined above, (6) Rf5(0ArSO2OH)2 wherein Rf5 and Ar are as defined above, (7) Rf5 [ OAr1(C0OH)2 ] 2 wherein Rf5 and Arl are as defined above,

(9) C6F13CH2ArSO2OH wherein Ar is as defined above, (10) Y-(COOH)n wherein n is 1-4 and Y is a fluorine-free organic residue having a molecular weight of from 15 to 5000, especially a hydrocarbon residue optionally containing one or more ether link; at least one of the hydroxy or acid components being a fluorine-containing compound.

Alkyl radicals which may be represented by R1, R2, R3, R4, R41 and R5 in the above defined compounds include both straight-chain and branched-chain radicals. Aromatic radicals which may be represented by Ar and Arl particularly include benzenoid radicals but the possibility of more complex aromatic radicals, for example naphthalene based radicals is not excluded.

Polyoxyalkylene chains mentioned herein particularly include chains of the formula:

wherein x and y are as defined above, Organic residues which may be represented by X in the compounds of class (N) or by Y in the acids of class (10) include aliphatic, cycloaliphatic andlor aromatic residues.

Ether-containing residues which may be represented by X and Y include oxyalkylene radicals and polyoxyalkylene chains.

The compounds comprising residues of an acid as defined above, i.e. esters, employed as lubricants in the compositions of the invention may be prepared using conventional esterification techniques by reacting one or more appropriate hydroxy compounds with one or more acids selected from classes (1) to (10) or ester-forming derivatives thereof, at least one of the ester-forming components being a fluorine-containing compound.

Hydrofluoroalkanes and hydrochlorofluoroalkanes which may be present as working fluids in the compositions of the invention typically have boiling points in the range from about -85 C to about 3000. Examples of suitable hydrofluoroalkanes and hydrochlorofluoroalkanes are given in the following table: Refrigerant Chemical Boiling Point No.Formula C at 1 bar R-23 CHF3 -82.1 R-32 CH2F2 -51.7 R-125 CHF2CF3 -48.5 R-22 CHClF2 -40.8 R-134a CF3CH2F -26.5 R-152a CHF2CH3 -24.7 R-134 CHF2CHF2 -19.7 R-124 CHClFCF3 -12 R-124a CHF2CClF2 -10.2 R-142b CClF2CH3 - 9.2 R-143 CHF2CH2F 5 R-133 CHClFCHF2 17 R-123 CHC12CF3 27.2 R-123a CHClFCClF2 28.2 A single hydrofluoroalkane or hydrochlorofluoroalkane may be employed as a working fluid in the compositions of the invention or, alternatively, a mixture of hydrofluoroalkanes and/or hydrochlorofluoroalkanes may be used. Any such mixtures may be azeotropes, zeotropes (mixtures of varying boiling point) or close boiling point mixtures.

The weight ratio of hydrofluoroalkane andlor hydrochlorofluoroalkane refrigerant to ether lubricant in the compositions of the invention is generally within the range from 99:1 to 1:99, preferably 99:1 to 70:30.

The compositions of the invention, which may also contain antioxidants, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers and extreme pressure additives, are useful in compression cycle heat transfer devices including refrigerator, air conditioning and heat pump systems and may be used for producing both cooling and heating.

The present invention is illustrated by reference to the following Examples.

Example 1 A lubricant composition comprising 90 mol Z of octafluoropentyl tricarballylate and 10 mol Z of icosafluoroundecyltricarballylate was prepared by esterification of tricarballylic acid with the appropriate fluorinated hydroxy compounds. The viscosity of the composition was determined both at 4000 and 100 C. The upper and lower miscibility limits of a composition comprising 10Z wiw of the lubricant and 90Z wiw of R134a were also determined. The lubrication effect of the lubricant was assessed using a four ball wear test with an applied load of 30 kg.

Example 2 The compound hexadecafluorononyl (3-methyl glutarate) was prepared by esterification of 3-methyl glutaric acid with the appropriate fluorinated hydroxy compound. The viscosity, miscibility and lubrication effect of this compound were determined in the same manner as in Example 1.

The results of Examples 1 and 2 were as follows: Four Ball Viscosity (cP) Wear Test Miscibility ( C) Example e 4000 @ 10000 (mm) Lower Upper 1 113 10.3 0.76 < -60 > +40 2 80 8.9 0.72 < -45 > +40

Claims

Claims 1. A composition for use in a compression type heat transfer device comprising: a) a hydrofluoroalkane or hydrochlorofluoro- alkane working fluid, and b) a sufficient amount to provide lubrication of a compound of the formula: (A) Rf1(Ar)x-CH2Q wherein Q represents -OR or -NR2 or a residue Z of an acid wherein R is a polyoxyalkylene radical, Ar is an optionally substituted arylene radical, x is O or 1 and Rfl is a fluorinated radical selected from

wherein a is 0-20, (ii) CF3(CF2)bCH2wherein y is 0-13, (iii) H(CF2CF2) wherein c is 1-4, (iv) CF3(CF2)dCFHCF2wherein d is 0-10, (v) CF3(CF2)e wherein e is 0-12, (vi) (CF3)2CFO(CF2CF2)f(CH2)g- wherein f is 0-4, and g is 0 or 1, and

wherein h is O or 1;;

wherein Q is as defined above, R1 is a Ol#20, alkyl radical and Rf2 is a fluorinated radical selected from: (i) H(CF2CF2)c wherein c is as defined above, (ii) CF3 (CF2)dCFHCF2- wherein d is as defined above, (iii) CF3(CF2)e- wherein e is as defined above, and (iv) (CF3)2CFO(CF2CF2)iwherein i is 0-4; (C) R20(CH2)kCCF2CF2)j(CH2)k0R21 wherein j is 1-6, k is 1-4 and R2 is hydrogen, alkyl having 1-20, carbon atoms, polyoxyalkylene or a fluorinated radical of the formula::

wherein Rf3 is Rfl as defined above or (CF3)2CFO(CF2CF2)iwherein i is 0-4, R21 is the same as R2 or a residue Z of an acid and R1 is as defined above, (D) Rf40ArOR wherein Rf4 is a perfluoroalkenyl radical having 6-12 carbon atoms, R is as defined above and Ar is an optionally substituted arylene radical, (E) Rf4OAr1(0R)2 wherein Rf4 and R are as defined above and Arl is an optionally substituted trivalent aromatic radical, (F) Rf4OArCONR3CCH2)w OR wherein Rf4, R and Ar are as defined above, R3 is a C1-4 alkyl group and w is 2-6, (G) Rf40ArCON [ (CH2)w OR ] 2 wherein Rf4, R, Ar and w are as defined above, (H) Rf4OArSO2NR3(CH2)w OR wherein Rf4, R, Ar, R3 and w are as defined above, (I) Rf4OArSO2NtCCH2)w R]2 wherein Rf4, R, Ar and w are as defined above, (J) Rf5(0ArOR)2 wherein Rf5 is a perfluoroalkenylene radical having 6-12 carbon atoms and Ar and R are as defined above, (K) Rf5 [ OAr1(OR)2 ] 2 wherein Rf5, R and Arl are as defined above,

wherein R is as defined above,

wherein R is as defined above, (N) X-(0R41)n (OZ)m#n wherein m is 1-8, m-n is 1-8, R41 is hydrogen or C1-6 alkyl, Z is a residue of an acid, and X is a fluorine-free organic residue having a molecular weight of from 15 to 5000;; (O) Ethers obtained by grafting fluoro-olefins, to alkylphenols, polyoxyalkylene polyols or end-capped polyoxyalkylene polyols, (P) fluorinated alkylene oxide polymers,

wherein R4 is CgH15 or C1,20-alkyl and each of x and y, independently, is 0-25, the sum of x and y being at least 5,

wherein R4, x and y are as defined above (S) Rf40ArR5 wherein Rf4 and Ar are as defined above and R5 is C6#30-alkyl, (T) Rf5(OArR5)2 wherein Rf5, Ar and R5 are as defined above.

and wherein Z is the residue of an acid selected from compounds of the formula: (1) Rfl-(Ar)x-COOH wherein Rfl, Ar and x are as defined above, (2) Rf40ArCOOH wherein Rf4 and Ar are as defined above, (3) Rf40ArSO20H wherein Rf4 and Ar are as defined above, (4) Rf40Arl(COOH)2 wherein Rf4 and Arl are as defined above, (5) Rf5(OArCO0H)2 wherein Rf5 and Ar are as defined above, (6) R#5COArSO2OH)2 wherein Rf5 and Ar are as defined above, (7) Rf5 [ OArl(COOH)2 ] 2 wherein Rf5 and Arl are as defined above,

(9) C6F13CH2ArSO2OH wherein Ar is as defined above, (10) Y-CCOOH)n wherein n is 1-4 and Y is a fluorine-free organic residue having a molecular weight of from 15 to 5000.