AU781207B2 - Working fluid compositions - Google Patents

Description

I

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Imperial Chemical Industries PLC Actual Inventor(s): Stuart Corr Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: WORKING FLUID COMPOSITIONS Our Ref 666123 POF Code: 453508/1453 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- WORKING FLUID

COMPOSITIONS

The present invention relates generally to working fluid compositions contained in heat transfer devices which comprise the lubricant and a heat transfer fluid.

Heat transfer devices of the mechanical compression type such as those used in refrigerators.

freezers, heat pumps and automobile air conditioning systems are well known. In such devices a heat transfer fluid of a suitable boiling point evaporates at low pressure taking heat from a surrounding zone. The resulting vapour is then compressed and passes 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 2" 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 heat transfer fluids used in these heat transfer devices include chlorine containing fluoroalkanes such as dichlorodifluoromethane (R-12), chlorodifluoromethane (R-22) and mixtures thereof with.

for example, fluoroalkanes such as l,1-difluoroethane (R-152a). However, such chlorine containing fluoroalkanes have been implicated in the destruction 310 of the ozone layer and as a result the use and production thereof is to be severely limited by international agreement. The use of certain fluoroalkanes and hydrofluoroalkanes in place of the chlorine containing fluoroalkanes has been proposed.

The fluoroalkanes and hydrofluoroalkanes of particular interest are those compounds which have comparable boiling points and other thermal properties to the chlorine containing fluoroalkanes which they are replacing, but which are also less damaging or benign to the ozone layer. Thus, R-12 is generally being replaced by a new refrigerant, 1.1,1,2-tetrafluoroethane (R-134a).

Hitherto, heat transfer devices have tended to use mineral oils as lubricants. The good solubility of chlorine containing fluoroalkanes with mineral oils allows the mineral oil to circulate around the heat transfer device together with the chlorine containing fluoroalkane, and this in turn ensures proper lubrication of the compressor.

Unfortunately, R-134a cannot be used as a direct replacement for certain of the refrigerants which are presently in use such as R-22 and R-502 (an azeotropic mixture of R-22 and chloropentafluoroethane R-115) since it does not possess comparable boiling characteristics and thermal properties.

O* o ;61 2 92832177 3/ 33 15-03-05:10:12 ;Ph II D5 OrmOnde Firzoatrick According to the present invention there is provided a working fluid composition comprising: a heat transfer fluid comprising a mixture of difluoromethane, 1,1,1,2tetrafluoroethane and pentafluoroethane; and a lubricant which is at least partially soluble in each component of the heat transfer fluid said lubricant comprising one or more compounds of general formula:

O

II

R(O-C-R')n wherein R is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylol ethane, trimethylol propane or neopentyl glycol, or the hydroxyl containing hydrocarbon radical remaining after removing a proportion of the hydroxyl groups from pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylol ethane, trimethylol propane or neopentyl glycol; each R' is, independently, H, a straight chain (linear) aliphatic hydrocarbyl group, a branched aliphatic hydrocarbyl group, or an aliphatic 20 hydrocarbyl group (linear or branched) containing a carboxylic acid or carboxylic *i acid ester substituent, provided that at least one R 1 group is a linear aliphatic hydrocarbyl group or a branched aliphatic hydrocarbyl group; and n is an integer.

The heat transfer fluid may comprise three or more components.

25 Preferred hydrofluoralkanes and fluoroalkanes which may be added are selected from the group consisting of 1,1,2,2-tetrafluoroethane (R-134), 1,1difluoroethane (R152a), 1,1,1-trifluoroethane (R-143a) and 1,1,2-trifluoroethane :0 0: (R-143).

The present invention is particularly concerned with the provision of a 30 working fluid composition which provides a useful replacement for the working fluids presently in use which comprise R-22 or R-502 as the refrigerant and a mineral oil lubricant. A working fluid composition in this respect is one which comprises: a heat transfer fluid comprising a mixture of: R-134a; 3 COMS ID No: SBMI-01163710 Received by IP Australia: Time 10:15 Date 2005-03-15 ;61 2 92832177 a 4/ 14-03-05:18:45 ;ph; Is 0 Ormonlde Fitzoat'rck difluoromethane and pentafluroethane (R-125).

sufficient to provide lubrication of a lubricant which is at least partially soluble in each component of the heat transfer fluid.

The fluid may also comprise 1,1,2,2-tetrafluoroethane (R-134).

Preferably, however, R-134a is the only tetrafluoroethane present.

Although the heat transfer fluid may comprise more than three components, it is preferably a ternary mixture. The mixture may be an azeotrope or near-azeotrope, but will normally be zeotropic.

A ternary heat transfer fluid according to the invention provides a suitable replacement for the R-22 and R-502 refrigerants which have been used hitherto in commercial refrigeration systems and related heat transfer devices.

One particularly preferred ternary heat transfer fluid for replacing R-22 is a mixture consisting of: 55 to 65% by weight; particularly about 60% by weight of R-134a; 25 to 35% by weight, particularly about 30% by weight of R-32; I and S(3) 5 to 15% by weight, particularly about 10% by weight of R-125.

Another particularly preferred ternary heat transfer fluid for replacing R-22 S. 20 is a mixture consisting of: 25 to 35% by weight, particularly about 30% by weight of R-134a; 45 to 55% by weight, particularly about 50% by weight of R-32; and 25 15 to 25% by weight, particularly about 20% by weight of R-125.

a. One particularly preferred ternary heat transfer fluid for replacing R-502 is a mixture consisting of; 45 to 55% by weight, particularly about 50% by weight of R-134a; 4 COMS ID No: SBMI-01162984 Received by.lP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 5/ 14-03-05:16:45 :Phl I Io Ormonde Firzoatrick 25 to 35% by weight, particularly about 30% by weight of R-32; and 15 to 25% by weight, particularly about 20% by weight of R-125.

Another particularly preferred ternary heat transfer fluid for replacing R-502 is a mixture consisting of: 45 to 55% by weight, particularly about 50% by weight of R-134a; 35 to 45% by weight, particularly about 40% by weight of R-32; and 5 to 15% by weight, particularly about 10% by weight of R-125.

All the percentages by weight quoted above are based on the total weight of the ternary heat transfer fluid.

I-

i. 15 Suitable lubricants may be selected from those currently used with R-134a provided that the requirement of at least partial solubility is met.

S**

i 'i o* o o* i *i COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 a 14-03-0515:45 ;Pht i s Ormonde FirzoariCk2 We have found that if a prospective lubricant is at least partially soluble in each component of the refrigerant mixture then it will be at least partially soluble in the refrigerant mixture itself, thereby enabling its use as a lubricant with that mixture.

The lubricants for use in the working fluid compositions of the invention are those selected from the class known as neopentyl polyol esters due, inter alia, to their generally high level of thermal stability. Suitable neopentyl polyol esters include the esters of pentaerythritol, polypentaerythritols such as di- and tripentaerythritol, trimethylol alkanes such as trimethylol ethane and trimethylol propane, and neopentyl glycol. Such esters may be formed with linear and/or branched alkanoic acids, or esterifiable derivatives thereof. A minor portion of an aliphatic polycarboxylic acid, eg. an aliphatic dicarboxylic acid, or an esterifiable derivative thereof may also be used in the synthesis of the ester lubricant in order to increase the viscosity thereof. However, where such an aliphatic polycarboxylic acid (or esterifiable derivative thereof) is employed in the 15 synthesis, it will preferably constitute no more than 30 mole more preferably S. no more than 10 mole of the total amount of carboxylic acids (or esterifiable derivatives thereof) used in the synthesis. Usually, the amount of carboxylic acid(s) (or esterifiable derivative thereof) which is used in the synthesis will be sufficient to esterify all of the hydroxyl groups contained in the polyol, but in :I 20 certain circumstances residual hydroxyl functionality may be acceptable.

The lubricant used in the composition of the inventions is on comprising one or more compounds of general formula: O .0 25 R(O-C-R 1 )n II 6 1 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;51 2 92832177 14-03-05;16;45 ;Ph It .DS Orm~o.,de FitzoatriCk

I.

I.

I**

20 vhe i h yrcro radical remainling after r Ro i s the yd o carb 5 onp from pentaerythritol dipefltaerythritol, tripentatrythritol. tr .imethylul ethane. trimethylol propane or neopentyl glycol- or the hydroxyl containling hydrocarbon radical remaiingi af ter removing a prop ortion Of th'e hydroxyl groups from pent arythritol. dipentaerythritol. tripentaerythrito 1 trimethylol ethanle. trimethilol Propane or neopentyl glycol; ty .asrih hi each

R

1 is. independeatY ,asrih hi (linear) al.iphatic hydrocarbyl group. a branched aliphatic hydrocarbyl group, or an aliphatic hydrocarbyl group (linear or branched) containlhg carboxylic acid or carbox1 Ylic acid eater substituent.

provided that at least one Yl group is a Linear aliphatic bydrocarbyl group or a branched aliphatic hydrocarbyl group; and n ic an integer.

The aliphatic hydrocarbyl groups specified for R1 above may be substituted. e.g. by pendant atoms or groups such as chloro, fluoro and bromo. andlor by in chain hetero atoms such as oxygen and nitrogen.

Preferably. however. such hydrocarbYl groups are unsubstituted and. except in the case where Rl is an aliphatic hydrocarbyl group containinlg a carboxylic acid or carboxylic? acid ester substituefit. containl only carbon and hydrogenl atoms.

The ester lubricants of Formula 11 may be prepared, by reactingS the appropriate polyol or mixture of polyols with the appropriate carboxylc acid or mixture of acids. Esterifiable derivatives of the carboxylic acids may also be used in the synthesis such as the acyl halides, anhydrides and lower alkyl este .rs 7 A a a.

S.

S

S

A.

*I *1 Al COMS IDNo: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;51 2 92832177 a a/ 14-03-05:18:45 ;Ph, 11,05 Ormnrle FjtZoatriCk therof.Suitable acyl halides are the IcYl chloride$ and &%uitable lower alkyl esters are temty ses Aliphatic polyca2rboxylic acids. or esterifiable derivatives thereof. may also be used in the synthesis of the ester lubricant. -Where an Aliphatic polycarboxylic acid is used in the syathesis of the ester lubricant, the resulting lubricant will comprise one or more compounds of Formula 11 in vhich at least one of the R 1 group' is an aliphatic hydrocarbyl group (linear or branched) containing a carboxylic acid or carboxylic acid ester substitueut. The ability of pollcfrbdIylic acids to react with two or more alcohol molecules provides a means of increasing the molecular weight of the ester formed and so a means of ncrasinlg the viscosity of the lubricant. Examples of such .1 polycarboxlic acids include maleic acid. adipic acid arnd succiflic acid, especially adipic acid. Generally.

2'J however, only monocarboxylic acids (or esterififtble derivatives thereof will be used in the synthesis of ester lubricant, and were polycarboxylic acids are used they will be used together with one or more r~ monocarboylic acids (or esterifiable derivatives 23 thereof and will constitute only a minor proportion of the trital am~uflt of carboxylic acids used in the .synthesis. Wheare an aliphatic polycarbozylic acid (or an esterifiable derivative thereof) is employed in the synthesis. it will preferably constitute no more than 30 mole Z. more preferably no more than 10 mole 2 of I the total amount of carboxylic acids used in the synthesis. with one or more monocarboxylic acids (or 9:70:esterifiable derivatives thereof) constituting the remainder.

Usually, the amount of the carboxylic acid(s) (or esterifiable derivative thereof) which is used in the COMS ID No: SBMI-011629a4 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 a 9/ 14-03-05:16:45 ;Phi Os Ormonlde Fitzoatrick synthesis will be sufficiet to esterify all of the hydrozyl groups contained in the polyol(s)- in which case the resultins lubricsant vill comprise one or more compounds of Formula II in which R is the hydrocarbon radical remaining after removing the hydrozyl groups from pentaerythritol, dipentaerythritol, tripentaerythr. :ol, trimethylol ethane. trimethylol propane or neopentyl glycol.. However, in certain circumstances ester lubricants which comprise residual hydroxyl functionality may be acceptable. Such lubricants comprise one or more ester compounds of Formula I in which R is the hydroxyl containing hydrocarbon radical remaining after removing a proportion of the hydroxyl groups from pentaerythritol, dipenterythritol, tripentaerythritol. trimethylol ethane, trimethylol propane or neopentyl glycol. Esters containing residual (unreacted) hydroxyl functionality 0 are often termed partial esters, and lubricants :containing them may be prepared by utilising an amount of the carboxylic acid or acids which is insufficient "~to eaterify all of the hydroxyl groups contained in the 25 polyol or polyols.

It will be appreciated that the preferred t oneopentyl polyol ester lubricants may comprise a single compound ef Formula II, i.e. the reaction product which is formed between a single polyol and a single monocarbozylic acid. fovsver, such eater lubricants may 3also com)rise a mired ester composition comprising two ~or more compounds of Formula II. Such mired ester compositions may be prepared by utilising two or more i polyols andlor two or more carbozylic acids (or esterifiable derivatives thereof) in the synthesis of the ester, or by combining a mixture of different esters each of which is the reaction product of a 9 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;1 2 92832177 a 10/ 14-03-05;16:45 ;Ph illPS Ornmolde FirzoatriCk particular polyol and a particular carboly lic acid.

Furthermore,. dif ferent mixed ester compositions each of which has been prepared by utilizinlg two or more -polyols and/or two or more carboxylic acids (or esterifiable derivative' thereof) in their synthesis, may also be blended together.

The preferred neopentyl polyol ester lubricanlts is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol.

dipefltacrythritol, trimethylol propane or neoperitYl glycol. Particularly preferred alcohol' for the synthesis of the ester are pentaerythritol.

dipentaerythritol and trimethylol propane.

OFO Preferably, each RI in Formula 11 is, ~indepenldently. a linear aliphatic hydrocarbyl groupY or a branched aliphatic hydrocarbyl group.

zoPreferred linear aliphatic hydrocarbyl groups for RI are the linear alkyl groups, particularly the C3-10 linear alkyl groups. more particularly the C 5 -10 linear alkyl groups ernd especially the C 5 s linear alkyl groups. Examples of suitable linear alkyl groups 2S include u-pefltyl. n-hexyl. n-heptyl. n-octyl. n-noriyl and n-decyl Esters containing such alkyl groups can be prepared by utilizing e linear alkanoic acid in the synthesis of the ester.

Preferred branched aliphatic hydrocal'byl groups for I 1 are the branched alkcyl groups particularly the .1..C4-14 branch.ed alkyl groups more particularly the branched alkyl groups and especially the C8-10 branched alkcyl group'. Examples of suitable branched alkyl groups include isopentyl, isohexyl. isoheptyl.

isooctyl, isonoflyl, isodecyl. 2-ethylbutyl.

Z-methylhexyl. 2.ethylheZyl. 3 5 COMS ID No: SBMI-01 162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 a 11/ 25 14-03-05;16:45 14-3-0; 1:45 ;Ph.1los Or-Onde Fitzoatrick 8 298277U 1/ neopentyl. neOhept71 and neodecyl. Esters containing sucha alkyl groups can be prepared by utili~ing a 3 branched alkanaic acid in the synthesis Of the ester.

In a particularly preferred embodiment Of the present invention. the ester lubricant comprises one or more eaters of general formula: 2.00

R

2 CO C- R 3 )p

III

wihe rein RZ is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol.

dipentaerythritol or trimethylol propanle; each R3 is. independently. a linear alkyl group or a branched alkyl groups and p is an integer of 3, 4 or 6, wherein one or more of the named polyols. one or more linear alkanoiC acids, or esterifiable derivatives thereof, and optionally one or more branched al1canoic azids, or esterifiable derivatives thereof, are 25 utilised ina the synthesis of the ester lubricant.

*..Preferably. a mixture of two or more linear *~**~alkatloic acids, in particular two, or esterifiable derivatives thereof, are utilised in the synthesis of the ester. Hore preferably. a mixture of one Or more *30 linear alkafloic acids, or aterifiable derivatives thereof, and one or more branched alkanoic acids, or esterifiable derivatives thereof, are utilised in the synthesis. Thus, particularly preferred ester lubricants of the invention are mixed ester compositions which comprise aplurality of compounds of Formula 111.

COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 14-03-05;1 :45 ;PhilI OS O o de F itzoat lick ;61 2 92832177 a 12/ Where a mixture of linear and branched alkanoic acids (or este.rifiable derivatives thereof) are utilived in the synthesis of the ester. as is preferred. the linear alkanoic acid(s) preferably constitutes t least 25 mole z e.g from 25 to mole Z, of the total amount of carboxylic acids used.

In this ay, at Least 25 mo I, eg. from 25 to mole Z. of the hydroxyl groups contained in the polyol or mixture of polyols may be reacted with the said linear alkanoic acid(S).

Ester based lubricants comprising one or more compounds of Formula I provide a particularly good balance between the properties desired of a lubricant and. in particular, exhibit good thermal stability.

good hydrolytic stability and acceptable solubility and PO O miscibility with the heat transfer fluid. As stated previously, the present invention is particularly 20 concerned with the provision of a working fluid composition which can replace the existing working Sluid compositions comprising R-22 or R-502 as the refrigerant. Refrieration systems which contain replacements for R-2 and R-502 typicolly operate at ::temperatures above those using R-134A as the sole i replacement refrigerant. Thus. it is particularly desirable that the lubricant which is used in a working fluid composition designed to replace the existing compositions based on R-22 and R-502 exhibits good oft* 30 thermal stability.

preferably,

R

2 is the hydrocarbon radical remaining after removing the hydroxyl groups from oo pentaerythritol or dipentaerythritol.

Preferred linear and branched alkyl groups for R 3 are those described above in connection with R 1 and are 12 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 13/ 14-03-05:18:45 ;Phill s Ormonde FitzoarriCk derived by utilising the corresponding alkanoic acids or esterifiable derivatives thereof.

An especially preferred ester based lubricant comprises a mixed ester composition which comprises a plurality of esters of Formula II and which is the reaction product of pentaerythritol, heptanoic acid and mixture of branched Ca.

1 o alkanoic acids. Preferably, the heptanoic acid wil constitute from 25 to 75 mofe of the total amount of acids utilised in the synthesis, with the branched Cgs- 0 acids constituting the remainder. Esterifiable derivatives of the acids may also be used in the synthesis of the ester.

The lubricant may optionally further include one or more polyalkylene glycols provided the lubricant meets the requirement of partial solubility. Suitable polyoxyalkylene glycol lubricants include hydroxyl group nitiated polyoxyalkylene glycols, eg. ethylene and/or propylene oxide oligomerslpolymers initiated on mono- or polyhydric alcohols such as methanol.

15 butanol. pentaerythritol and glycerol. Such polyoxyalkylene glycols may also be end-capped with suitable terminal groups such as alkyl, eg. methyl groups.

A preferred polyoxyalkylene glycol lubricant is one having an average molecular weight in the range of from about 150 to about 3000 and comprising one or more compounds of general formula: A(-O-(CHzCH(CH 3 )O),(CHzCHO),-Q), a.* S wherein e. A is the residue remaining after removing the hydroxyl groups from a hydroxyl containing organic compound; Q represents an optionally substituted alkyl, aralkyl or aryl group: I and m are independently 0 or an integer provided that at least one of I or m is an integer; and x is an integer.

The polyoxyalkylene glycol lubricant may be prepared using conventional techniques. Such techniques are well known to those skilled in the art. Thus, in one method a hydroxyl containing organic compound such as an alcohol is reacted with ethylene oxide and/or propylene oxide to form an ethylene oxide 13 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 a 14/ 26 14-03-05:16:45 ;Ph, los Or-onde FitzoarriCk Sand/or propylene oxide oligomer/polymer containing terminal hydroxyl groups which is subsequently etherified to give a polyoxyalkylene glycol of Formula I.

The polyoxyalkylene glycol lubricant which is finally formed will not usually consist of a single compound of Formula I, but will usually comprise a mixture of such compounds which vary from one another in respect of the degree of polymerisation, i.e..the number of ethylene and/or propylene oxide residues.

Moreover, a mixture of alcohols and/or phenols may be used as initiators in the formation of the polyoxyalkylene glycol lubricant, and a mixture of etherifying agents which provide different Q groups may also be used. The molecular weight of a polyoxyalkylene glycol lubricant comprising a mixture of compounds of Formula I will represent the average molecular weight of all the compounds present, so that a given lubricant may contain specific polyoxyalkylene glycols "i which have a molecular weight outside the range quoted above, providing that the average molecular weight of all the compounds is within that range.

15 The moiety A in the polyoxyalkylene glycol of Formula I is the residue remaining after removing the hydroxyl groups from a hydroxyl containing organic compound. Such compounds include the mono- and polyhydric alcohols and S phenols. Where the hydroxyl containing organic compound which is used as an initiator in the formation of the polyoxyalkylene glycol is a monohydric alcohol or 20 phenol, A is preferably a hydrocarbyl group and more preferably is an alkyl, aryl, ialkaryl or aj!kyi group, especially alkyl. Suitable alkyl groups for A may be selected from tj straight chain (linear), branched or cyclic alkyl groups.

Preferably, A is a C1.12, particularly a Ci.0o and especially a C01 alkyl group.

Specific examples of alkyl groups include methyl, ethyl, n-propyl. isopropyl, n- 1 25 butyl, Isobutyl, sec-butyl, tert-butyl, the various pentyl groups, the various hexyl groups, cyclopentyl, cyclohexyl and the like. Particularly preferred alkyl groups for A are the C,.12, particularly the and especially the straight chain alkyl groups, examples of which have been listed above. An especially preferred alkyl group for A is methyl or n-butyl.

Other suitable hydrocarbyl groups for A are those which remain after removing a hydroxyl group(s) from benzyl alcohol and phenols such as phenol, cresol, nonylphenol, resorcinol and bisphenol

A.

14 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 a 15/ 26 14-03-05;:1645 ;Ph.1'1-s O-'o0de FitzoatriCk Where a polyhydric alcohol is used in the formation of the polyoxyalkylene glycol, A Is preferably a hydrocarbon radical. Suitable hydrocarbon radicals for A are those which remain after removing the hydroxyl groups from polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6hexanediol, diethylene glycol, dipropylene glycol, cyclohexane dimethanol, glycerol, 1,2,6-hexane triol, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol. A particularly preferred hydrocarbon radical for A is that remaining after removing the hydroxyl groups from glycerol.

The moiety Q in the polyoxyalkylene glycol of Formula I is an optionally substituted alkyl, aralkyl or aryl group. A preferred optionally substituted aralkyl group for Q Is an optionally substituted benzyl group. Preferred optionally substituted aryl groups for Q include phenyl and alkyl substituted phenyl groups.

o o..

Preferably, Q is an optionally substituted, for example halogen substituted, alkyl group, particularly an optionally substituted C 1 12 alkyl group and more particularly 15 an optionally substituted C1, alkyl group. Suitable alkyl groups for Q may be selected from the straight chain (linear), branched or cyclic alkyl groups, especially the linear alkyl groups. Although the alkyl groups for Q are described as being optionally substituted, they are preferably unsubstituted. Accordingly, particularly preferred alkyl groups for Q are selected from methyl, ethyl, propyl, 20 Isopropyl and the various butyl groups. An especially preferred alkyl group for Q is methyl.

The polyoxyalkylene glycol of Formula I may be a polyoxyethylene glycol, S* a polyoxypropylene glycol or a poly(oxyethylene/oxypropylene) glycol. In the latter case, the ethylene and propylene oxide residues may be arranged randomly or in blocks along the polymer chain. Preferred polyoxyalkylene glycols are the polyoxypropylene glycols and the poly(oxyethylene/oxypropylene) glycols.

The lubricant will typically be part of a lubricant composition which also comprises one or more of the additives which are conventional in the refrigeration lubricants art. Specific mention may be made of oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, viscosity index improvers, anti-wear agents and extreme pressure resistance additives. Such additives are well known to those skilled in the art. Where the lubricant is part of a'lubricant composition containing one or more additives, such additives may be COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 a 16/ 14-03-05;18:45 ;Ph ii .05 Or-Once F,tz,)atrick *present In the amounts conventional In the art. Preferably, the cumulative weight of all the additives will -not be more than eg. of the total weight of the lubricant composition.

Suitable oxidation resistanice and thermal stability improvers may be selected from the diphenyl-, dinaphthyl-, and phenylnaphthYl-amines. the phenyl and naphthyl groups of which may be substituted. Specific examples Include N.N'-diphenyl phenytenediamifle; p-octyidiphenyamfifle, p, p-d ioctyld iphenyla mine, N-phenyl-1.flaphthyI amine, N-phenyl-2-naphthyi amine.

00:..

*16 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 a 17/ 14-03-05;18:45 ;Ph jiip OrO~d N.(p-dadcYL).phenli;- 5phhYI &mine, di-l-nAPhthyl amin, an di2~nahthl amine. ther suitable oxidationl resistance and thermal stability improvers may be selected from the phenothiaZinee such so N-alkylPhanOthiazines and the hindered phenols such as 6$(t-bLtyl) phenol, Z6-di-(t-butyl) phenol, 4-mahyl2.6di-(-buyl)phenol and 4~.4netbylfneb(26df-tbtl phenol).

Suitable cuprous metal deactivators may be selected from imidazole. benzamidezOle- Z-mercaptaboutthiazole, 2 5 -dimectaptothiadiazole alicylidins-propylenedismine, pyrazole. benzotriazole.

tolutrizzole. 2 -mothylbeflzamidazole. pyrazoI6. and methylenle bia-benzotrisbole. Examples of *ore general metal deactivators nd/or corrosion inhibitors include organic acids and the esters, metal.

salts and anhydrides thereof, such as N-0 4 olel-arcosine, sorbit .an monooleate, lead naphthenste. dodecenyl-luceinic acid and its partial esters aind amides, and 4-noTnylpbenoxy acetiC'acid- *1~.eeprimary, secondary and tertiary aliphatic and cycloliphatic amines and amine salts of organic and inorganic acids. such as oil soluble allcylanmofium carboxylates; hetetocyclic nitrogen containing *...compounds. such as thiadiazoles, substituted imidazoliles. and azatolines; quinoline6. quinOfles and anthraqtuinones; ester and amide derivatives of aikeiiyl succinic anhydrides or acids, dithiocarbamates.

dithiophosphates; and amine salts of allcyl. acid phosphates and their derivatives.

Suitable viscosity index improvers include polymethacrylate polymers. copolymers of vinyl pyrrolidone and mathacrylates. polybutene polymers. and copolymers of styrenle and acrylates.

17 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 0 18/ 14-03-05;18:45 ;PhillOS Ormonde FitzoatriCk Examples of suitable. anti-wear and extreme pressure resistance agents include sulphurised fatty acids and fatty acid esters, such as gulphurised octyl tallate: sulphurised terpeoes; sulphurised olefins; organopolysulphides; organo phosphorous derivatives including amine phosphates, alkyl acid phosphates, dialkyl phosphates, aminedithiophosphates, trialkyl and triaryl phosphorothionates, trialkyl and triaryl phosphines, and dialkylphophhites. amine salts of ~phosphoric acid monohexyl ester, amine salts of dinonylnaphthalene sulphonlte. triphenyl phosphate.

.trinaphthyl phosphate. diphenyl cresyl and dicresyl phenyl phosphates, tricresyl phosphate. naphthyl :diphenyl phosphate, triphenylphosphorothionateC; dithiocarbamates. such as an antimony dialkyl dithiocarbamate chlorinated andlor fluorinated hydrocarbons, and zanthates.

The working fluid compositions of the invention vill typically comprise a major amount of the heat .1 *transfer fluid and a minor amount of the synthetic 0lubricant, preferably, the working fluid compositions of the invention will comprise from 50 to 99 2 by 23 weight. more preferably from 70 to 99 1 by weight, of the heat transfer fluid and from i to 50 i by weight.

,more preferably from 1 to 30 Z by cweight, of the lubricant based on the total weight thereof.

The working fluid compositions are useful in all types of compression cycle heat transfer devices. Thus, they may be used to provide cooling by a method involving condensing the heat transfer fluid and thereafter evaporating it in a heat exchange relationship vith a body to be cooled. They may also be used to provide heating by a method involving *condensing the heat transfer fluid in a heat exchange 18 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 4 19/ 26 14-03-05;18:45 ;Ph ii *s Ornonde FirzoatriCk relationship with a body to be heated and thereafter evaporating it.

The working fluid compositions of the invention provide a good compromise between performance and low or zero ozone depletion. They are especially suitable for applications currently satisfied by refrigerants R-22 and R- 502.

The present invention is now illustrated, but not limited, with reference to the following Examples.

Examples The working fluid compositions of the invention which were investigated in the following Examples comprised a lubricant and a heat transfer fluid which was a ternary mixture of 1,1,1,2-tetrafluoroethane (R-134a), difluoromethane

(R-

32) and pentafluoroethane (R-125).

1,1,1,2-tetrafluoroethane, difluoromethane and pentafluoroethane are at !least partially soluble in each of the lubricants tested which means the converse :15 is true, each of the lubricants tested will be at least partially soluble in each of these hydrofluoroalkanes. Moreover, each lubricant tested is at least partially soluble in the ternary mixtures themselves.

Fluoroalkane heat transfer fluids such as R-134a have different solubility I characteristics to chlorine containing fluoroalkanes and tend to be insufficiently ii: l 20 soluble in mineral oils to allow the latter to be used as lubricants.

Example 1 The lower miscibility temperatures of a series of compositions comprising 15% w/w of a lubricant and the complementary percentage of a single hydrofluoroalkane selected from R-134a, R-32 and R-125 were determined. The 25 compositions were prepared and the lower miscibility temperatures of each S" composition i.e. the lowest temperature at which the lubricant remained miscible with the heat transfer fluid was determined using the following procedure: a set amount of the lubricant to be tested was placed in a previously evacuated thick walled test tube and the tube was then placed in a cooling bath regulated at the desired temperature. Once the tube was sufficiently cold, a set amount of the heat transfer fluid was condensed into the test tube. The tube was then removed from the cooling bath and the contents allowed to warm to room temperature. After the contents had been allowed to equilibriate at room temperature, they were agitated and visually examined for evidence of phase 19 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 14-03-05:18:45 ;Phi II D Ormonde Firzoatrick ;el 2 92832177 20/ separation (the mixture looks cloudy). If there was no evidence of phase separation, the temperature of the mixture was lowered in a cooling bath at a rate of 1°C per minute until phase separation was observed. The temperature at which phase separation was first observed was recorded as the lower miscibility temperature. The results are shown in Table 1. In Table 1 it will be noticed that the lower miscibility temperatures are in some cases quoted as being less than This means that at -60*C phase separation was not observed.

TABLE 1

I

LUBRICANT LOWER MISCIBILITY TEMPERATURE R-134a R-32 R-125 PE6 <-60 0 "EMKARATE" (TM) RL-212 -25 20 "EMKARATE (TM) RL-184 10 20 "EMKAROX" (TM) RL-118 <-60 I I denotes immiscibility over the temperature range -50°C to PE6 is an ester of pentaerythritol and n-hexanoic acid.

'EMKARATE' (TM) RL-212 is a commercially available ester based lubricant for use with R-134a obtainable from ]CI Chemicals Polymers Ltd.

Specifically, the lubricant comprises an ester of trimethylol propane and heptanoic acid.

'EMKARATE' (TM) RL-184 is a commercially available ester based lubricant for use with R-134a obtainable from ICI Chemicals Polymers Ltd.

Specifically, the lubricant comprises an ester of pentaerythritol, heptanoic acid and a mixture of branched CB- 10 alkanoic acids.

'EMKAROX' (TM) RL-118 is a commercially available polyoxyalkylene glycol based lubricant for use with R-134a obtainable from ICI Chemicals Polymers Ltd. Specifically, the lubricant comprises an end-capped polyoxyalkylene glycol.

'EMKARATE' and 'EMKAROX' are trademarks of ICI Chemicals Polymers Ltd.

Example 2 In this Example a series of working fluid compositions were prepared comprising varying proportions of a lubricant comprising an ester of pentaerythritol and n-hexanoic acid and a heat transfer fluid comprising 50% by COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 a 21/ 14-03-05:18:45 ;Ph.11- Ornonde FirzoatiCk weight of R-134a, 30% by weight of R-32 and 20% by weight of R-125. The lubricant is at least partially soluble in each of the components of the heat transfer fluid and also in the fluid itself. The lower miscibility temperature of each composition was again determined. The compositions were prepared and the lower miscibility temperatures determined using the procedure described in Example 1.

The results are shown in Table 2. In Table 2 it will be noticed that the lower miscibility temperature of some of the compositions is quoted as being less than -50C. This means that at -50 0 C phase separation was not observed.

I.

I:o I i 6. 21 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 4 22/ 14-03-05;18:45 ;Pn. I ps Ormonde Fitzoatrick TABLE 2 Vorking fluid composition I by weight of I by veight of heat Lower miscibility lubricant transfer fluid temperaturc 10.2 89.8 22.0 78.0 -48 29.7 70.3 41.6 58.4 48.6 51.4 60.7 39.3 it will be appreciated that the ternary mixtures of R-134a, R-32 and R-125 which form the subject of the above Examples can also be used in combination with other neopentyl polyol ester type lubricants to yield viable working fluid compositions. Moreover, ternary mixtures of R-134a, R-32 and R-125 15 comprising different proportions of the constituent hydrofluoroalkanes to the mixtures exemplified above can also be used in combination with neopentyl polyol ester type lubricants to yield viable working fluid compositions.

4 22 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14

Claims (4)

14-03-05:16:45 ;Ph. 1iips Ormnce Firzoatrick The cla:ims defitiig. tho tnvcnt Eon are as fol lows: 1. A working fluid composition comprising; a heat transfer f luid comprising a irlixture of'- difluoromethane, 1,t.t,2-tetraf uoroethane and peritafluoroethKane; I and a lubricant which is at least partially soluble in each componentof the heat transfer tluid said lubricant comprising one or more compounds of general formuila: 0 *1R(O -C -R) I whRi is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol. tripentaerythrltot, trimethylol ethane, trimethylol propane or neopentyl glycol, or the hydroxyl containing hydrocarbon dia remaining after remnoving a proportion of the hydroxyl groups from 'I pentaerythritol, dipentaerythrltol, tripentaerythritol, trimethylo. ethane, trimethylol propane or neopentyl glycol; *each R. IIs, independently, H, a straight chain (kinear) aliphatic hydrocarbyt group, a branched aliphatic liydrocarbyl group. or an aliphatic hydrocarbyl group (linear or branched) containing a carboxytic acid or carboxylic acid ester substituent, *provided that at least one RIgroup is a. linear alipha'tic hydrocarbyl group or a branched aliphatic hydrocarbyl group; and n is'an integer. 23 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 a 24/ 14-03-05;18:45 ;Phill os Ormonide Firzoatrick 2. A working fluid composition of claim 1 wherein the heat transfer fluid (A) comprises 55 to 65 by weight of R-134a; 25 to 35 by weight of R-32; and 5 to 15% by weight of R-125. 3. A working fluid composition of claim 1 wherein the heat transfer fluid (A) comprises 25 to 35 by weight of R-134a; 45 to 55 by weight of R-32; and 15 to 25% by weight of R-125. 4. A working fluid composition of claim 1 wherein the heat transfer fluid (A) comprises i; 45 to 55 by weight of R-134a; 25 to 35 by weight of R-32; and 15 15 to 25% by weight of R-125. 5. A working fluid composition of claim 1 wherein the heat transfer fluid (A) comprises 45 to 55 by weight of R-134a; S(2) 35 to 45 by weight of R-32; and 5 to 15 by weight of R-125. A working fluid composition as claimed in any one of claims 1 to wherein the linear and branched hydrocarbyl groups specified for R 1 are unsubstituted and the carboxylic acid or carboxylic acid ester containing hydrocarbyl group specified for R 1 contains no other substituents 25 7. A working fluid composition as claimed in any one of claims 1 to 6 °wherein the lubricant comprises one or more compounds of Formula II in which R is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylol ethane, trimethylol propane or neopentyl glycol. 8. A working fluid composition as claimed in claim 7 wherein the lubricant comprises one or more compounds of Formula II in which R is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol, trimelhylol propane or neopentyl glycol. 9. A working fluid composition as claimed in claim 8 wherein the lubricant comprises one or more compounds of formula II in which R is the 24 COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;61 2 92832177 25/ 14-03-05;16:45 ;Ph I ,Ds Ormonde Frzoatrick hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol or trimethylol propane. A working fluid composition as claimed in any one of claims 1 to 9 wherein the lubricant comprises one or more compounds of Formula II in which each R' is, independently, a linear alkyl group or a branched alkyl group. 11. A working fluid composition as claimed in claim 10 wherein at least one R' group is a linear alkyl group. 12. A working fluid composition as claimed in claim 10 or claim 11 wherein at least one R 1 group is a linear alkyl group and at least one R 1 group is a branched alkyl group. 13. A working fluid composition as claimed in claim 1 wherein the lubricant comprises one or more esters of general formula: 0 15 R 2 (O-C-R 3 )p [II wherein R 2 is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol, dipentaerythritol or trimethylol propane; each R 3 is, independently, a linear alkyl group or a branched alkyl group; 20 and p is an integer of 3, 4 or 6, wherein one or more of the named polyols, one or more linear alkanoic i' acids, or esterifiable derivatives thereof, and optionally one or more branched alkanoic acids, or esterifiable derivatives thereof, are utilised in the synthesis of 25 the ester. 14. A working fluid composition as claimed in claim 13 wherein a mixture of one or more linear alkanolc acids, or esterifiable derivatives thereof, and one or more branched alkanoic acids, or esterifiable derivatives thereof, are utilised in the synthesis of the ester.

15. A working fluid composition as claimed in claim 13 or claim 14 wherein the lubricant comprises one or more compounds of Formula III in which R 2 is the hydrocarbon radical remaining after removing the hydroxyl groups from pentaerythritol or dipentaerythritol.

16. A heat transfer device containing the working fluid composition claimed in any one of claims 1 to COMS ID No: SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14 ;81 2 92832177 u 2e/ 14-03-05;16:45 ;Phi i Ds Ormondle Fitzoatrick

17. A working fluid composition as claimed in claim 1 substantially as hereinbefore described with reference to any one of the examples. DATED: 14 March, 2005 PHILLIPS ORMONDE FITZPATRICK Attorneys for: IMPERIAL CHEMICAL INDUSTRIES PLC 0 0 6J26 COMS IDNo; SBMI-01162984 Received by IP Australia: Time 16:54 Date 2005-03-14