, SAE TECHNICAL
`" PAPER ssmss
`
`-
`
`951052
`
`.
`
`The Development of PAG Refrigeration
`Lubricants for Air Conditioner with HFC134a
`
`Masato Kanoko, Tsuneo Konlshi,
`Yasuhlro Kawaguchl, and Mlnoru Takagl
`ldemltsu Kosan Co-. Ltd.
`
`Reprinted from: Design Elements In Automotive climate control Systems
`(SP-1085)
`
`I
`
`S I
`
`Th E I
`
`lnternatlonal Congress and Expoaltlon
`o‘ EFor.A:IzI’r1r:%g agfilfty
`patron, mcmgan
`“Land SunAirand Space,
`February21-Maroh2,1995
`‘
`’N7'5”NA7"0N/H-.
`
`
`Arkema Exhibit 1120
`
`Page 1 of 9
`
`

`
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` GLOIAL MOBILITY IMTABASE
`
`All sAEpapm. standards. and sotoctad
`book: an abstracted and indexed In the
`Global Mobility Database.
`
`No part at this publication may by reproduced in any form. in an electronic retrieval
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`
`ISSN 0148-7191
`Copyright 1995 socloty ot Automotive Engtn-urn. lno.
`
`Positions and opinions advanced in this paper are those of the authorts) and not
`necessarily thcsa of SAE. The author is scioty responsible tor the content of the
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`
`Prtntod tn uss
`
`'
`
`-
`
`mom
`
`
`
`
`
`
`
`Page 2 of 9
`
`

`
`The Development of PAG Refrigeration Lubricants
`for Air Conditioner with HFC134a
`
`Maeato Ktmelto, Tsuneo Konlshi, Yaatthiro Kawagttehl, and Mlnoru Taltagl
`ldamltsu Koaan Go.. Ltd.
`
`951052
`
`ABSTRACT
`
`In order to clarify the relationship between the
`chemical structure of PAG (polyalkyicne glycol) and the
`performance characteristics as the refrigeration lubricants
`used for HFC134a,
`performance tests were conducted
`using PAOs with different end groups and alkylene oxide
`chains in the presence of HFC134a.
`Newly developed dimcthyl ether capped PAGs having
`more titan 70 mol.% PO (propylene oxide) to less than 30
`mol.% E0 (ethylene oxide)
`as a monomer ratio were the
`most preferable of all PAGS tested. The refrigeration
`lubricants using these PAGs have been successfully
`introduced into the marital
`for mobile air conditioning
`systems with refrigerant HFC134a.
`
`INTRODUCTION
`
`The phase-out program of the production and use of
`chlorolluorocarbones (Ci~‘Cs) is underway in compliance
`with the Montreai Protocol on substances that depletethe
`earth's ozone layer in 1987. CFCIZ having been used as
`the refrigerant for mobile air conditioning systems should
`be completely phased out by 1995 and replaced by nonozene
`depleting HFC134a. Mineral oil
`type refrigeration
`lubricants currently used with CFCl2 are unable to be
`applied for compressors with HFC134a because of their
`poor solubility.
`Some kinds of PAGS are soluble in
`HFCl34a. However, there are few published technical
`papers regarding the application of different types of PAGs
`for refrigeration lubricants for HFC134a f”.
`
`This report intends to clarify the influence of the
`structure of PAGs on the performance
`characteristics as the refrigeration lubricant.
`such as the
`solubility in HFCl34a and CFCl2 as taking into account
`the retrofit application. the lubricity, thermal stability. and
`
`hydrolytic stability in the presence of HFC134a and
`
`“‘ Numbers in brackets designate references at end of paper.
`
`oxitlative stability.
`
`1. FLUIDITY CHARACTERISTICS OF PAGS
`Refrigeration lubricants are required to circulate
`smoothly in the refrigeration system with refrigerant.
`It is
`influenced by the lubricant viscosity between the expansion
`valve and suction of the compressor in the system at which
`the temperature is in the range from -30 to 10C. The lower
`the lubricant viscosity.
`the smoother the circulation of the
`lubricant in the systetn.
`lubricants are necessary to have
`On the other hand.
`high viscosity. approximately 10 mmzls at I00 ‘C. from
`the view point of the lubrication of machine parts exposed
`to a high temperature in the system. Therefore. PAGs with
`HVl(high viscosity index) are suitable as base fluids for
`refrigeration lubricants. Consequently. concerning the
`fluidity of PAGS. following specifications are the guide line
`to select appropriate refrigeration lubricants.
`
`Viscosity at lt)0'C (mm2/s) :
`VI
`_
`:
`Pour Point (‘C )
`
`8 ~ 12
`over 200
`below -40
`
`1.] EFFECT OF END GROUPS
`
`The effect of the difference in end groups on the
`VI(viscosity index) of PAG was evaluated using derivatives
`of PPG(polypropylene glycol). 'l'he viscosity of synthesized
`samples are approximately 10 mm2/s at 100 ‘C.
`The
`chemical structures and physical properties of these samples
`are shown in Table 1.
`
`The influence of numbers of hydroxyl groups on the
`V! of PFC} are shown in Fig.1, when one or both of
`hydroxyl groups of PPG were methyl ether capped. The Vl
`of FPO noticeably increases with the decrease of hydroxyl
`groups. The lower the temperature,
`the stronger the
`molecuiar interaction due to hydrogen bonds between
`hydroxyl groups. Therefore. Vi of PPGS having hydroxyl
`groups are smaller than these of diether capped PPGs.
`
`Page 3 of 9
`
`

`
`the other is the most effective end group to
`Furthermore,
`cap hydroxyi groups in order to increase the Vi of PPG in
`comparison with ester or carbonate as shown as well in
`
`260
`
`Dlrnathyl other
`Glppud
`
`
`
`,. 2*"‘E
`
`Irlnnomothyi other
`
`E
`
`1
`
`GIN?"
`
`°'‘’'“‘
`
`°’°'”’°""'
`
`
`
`’ no
`
`‘M0
`
`1
`Number of Hydroxyi Groups
`Fig.1 Influence of Number of Hydroxyl
`Groups on the V5 of was
`
`2
`
`Fig.
`
`1.2 EFFECT OF MAIN CHAINS
`
`1 .
`The effect of the chernicai structureof main chains on
`
`the VI of PAC! was evaluated using dimethyi ether capped
`PAGs. Monomers used for the synthesis of PAGs are
`various ratios of E0 and PO. and those of PO and B0
`
`(butyienc oxide). The viscosity of synthesizedsampies are
`controicd approximately 10 mm’)/s at 100 "C.
`The
`monomer ratios and physical properties of these samples are
`5h°""“ "' Tm‘ 2-
`-
`The influence of
`types of monomers and monomer
`ratios on the Vi of diether capped PAOs are shown in
`Fig.2. The V! or the PAGs noticeably increases with the
`decrease of carbon numbers of monomers from E0 to 130.
`This is attributable to the carbon number of branched alkyl
`groups on the main chain of M03, of which decrease
`causes the increase of VI. As far as the vlscosity-
`temperature characteristics areconcemed, PEG (polyethylene
`glycol) is the most excellent. However. its pour point is
`
`too high to be in practical use as shown in ihbie 2.
`Taking into account
`both the pour point
`and
`viscosity-temperature characteristics. dimethyl ether capped
`PPCls or copolymer type PAGs having more than 50 mol.%
`P0 to less than 50 mol.% E0, or more
`70 moi.% P0
`to less than 30 mo}.% BO as a monomer ratio meet the
`3“‘d° ""5 °f ""3 “P°°m°“5°“3 f°' “"i‘“‘Y °hm°l°“'3'5°5-
`
`
`
`2”
`
`
`
`...,‘.
`
`"" HQ‘
`
`
`
`
`
`
`no -
`§ 290
`
`9°“ I
`uh.
`M
`
`lllllllllllllllliill
`
`.
`
`1,0
`
`no
`
`
`
`-0
`
`
`
`
`
`
`
`
`
`'°
`
`F030
`'0
`Iago
`EOIPOIBO Hallo
`Fig.2 lniiuence of Compositions of Main chain
`on the V! of Dlethar capped PAGs
`
`Table 1. Physical Properties of PPGJ with Different End Groups
`
`No.
`End Groups
`Chamlcalslructure Viscosity [rm-n’lI]
`V]
`pompotm
`
`@4o‘c @1oo'c
`yo]
`
`-40.0
`137
`9.307
`61.92
`HO-Po .H
`Alcohol
`1 Ai<=°h°'
`-45.0
`179
`9.315
`51.62
`cnm‘r>o;33H
`Alcohol
`2 Ether
`-45.0
`214
`9.760
`44.36
`cHao.(p-otncut
`Ether
`3
`5918-’
`.42_5
`177
`10.17
`54.53
`ctncoo4t=otn.cocH.
`Ester
`4 Ester
`.3;-_5
`150
`9.640
`5 Carbonate CarbonalecH»ooo_o~u=otn—cooctta 58.10
`l
`
`Table 2. Physical Properties of FAG: with Different Backbone
`
`No.
`Polymer
`Chemical Structure
`Viscosity tmn-at
`v|
`pom pom;
`3a°kb°"°
`@4o'c @1oo'c
`(‘Cl
`
`
`35.0
`245
`9.960
`Solid
`-CH:
`CHr0lE0ln
`E0
`3
`5
`229
`8.575
`35.92
`CH!C-{ECWO-7fJ)fl-CH1
`Eorponm
`7
`-50»
`227
`1 1.04
`43.79
`cueoteomomstncu.
`EOIPO-5/5
`8
`-50,
`225
`9,750
`42,43
`Cl-{:0-iEOn'PO-Smn-CH:
`5o;po_3;7
`9
`.50)
`195
`10,34
`5.4_42
`CHsO-POIBO-Tf3)fl-CH:
`po/Bo‘-N3
`10
`-so»
`187
`10.92
`57.03
`°”*°¢P°'1*°-5'5ln-CH4
`P0/BO-515
`1 Y
`
`
`
`
`
`
`
`°”‘°"’°"' ‘W’ 54.13 sass 15?so12 50>
`
`
`
`Page 4 of 9
`
`

`
`follows:
`
`CST at 10 wt.% of the iubricant in the refrigerant
`High temperature region ( ‘C ) : over 70
`Low temperature region ( ‘C ): bellow -40
`The influence of the end groups on CSTs of FPO: in
`I-IFC134a measured in a high temperature region is shown
`in Fig.4. The end groups having carboxyl group. such as
`carbonate and ester. exhibit better solubility than ether and
`alcohol. However. all PPGs with different end groups tested
`here were able to meet
`the required CST in a high
`temperature region described above.
`
`utmgnyt other
`cupped
`
`Ttmparuuro('c)
`
`0
`
`2 0
`1 ll
`Oil Content
`
`(Mei)
`
`Cl 0
`
`4 0
`
`Fig.4 influence at End Groups on CSTs of Was
`
`types of monomers and monomer
`The influence oi’
`ratios in main chains on CSTs of PAG.-J in I-IFCl34a was
`evaluated using diether capped PAGs in a high temperature
`region. Test results are shown in Fig.5.
`PEG, PPG and
`copolymers of E0 and P0 show good solubility satisfying
`the requirement. However, as far as copotymers of P0 and
`B0 are concerned. the larger the B0 ratio, the poorer the
`solubility. Consequently it is very difficult to meet the
`requirement.
`CS’Ps in CFCIZ and I-iFCl34a in a high temperature
`
`2. SOLUBILITY IN HFCl34a AND CFCIZ
`The solubility of refrigeration iubrictints in refrigerants
`is indicated using CST (critical soluble temperature). at
`which the lubricant begins to separate from the mixture of
`the lubricant and refrigerant 93. CST is plotted against wt.%
`concentration of the lubricant in the mixture. One of the
`
`test results measured using the mixture of dimethyl ether
`capped copolymer type PM] and l{FCl34a is shown in
`Fig.3. Two CST curves can be obtained from one sample.
`
`1-:
`i
`1%-
`CST In
`tgh ‘romp. Region
`
`
`
`
`
`
`
`o
`
`20
`10
`Olt Content (vim)
`
`so
`
`to
`
`Fig.3 Two CST Curves of PAG(No.10)
`In HFC134a
`
`CST curve drawn at the upper part of the figure in other
`words. in a high temperature region.
`is obtained when
`heating the mixture from a room temperature. Another CST
`curve existing in a low temperature region is obtained when
`cooting the mixture from a room temperature.
`'
`The CSTs of all samples described in Table I and 2
`were measured using refrigerants both i-lFC134u and
`CFCI2. A part of the test results is
`shown in Table 3.
`From point of view of OEMs(original equipment
`manufacturers) and car manufacturers. the acceptable CS'Is
`of refrigeration lubricants In order to be sufficiently used
`for mobile air conditioning systems are considered to be as
`
`Table 3. CST of PAG9
` HZI:j—
`
`
`
`CST ['C]
`
`No, Chamicalstruciure
`
`
`CFC-13
`l-If-‘C1.'34a
`HTH
`LTH
`LTH
`HTH
`
`
`10%tov. 15% zmteov. 10%5v.otcententast. 10%
`
`
`
`
`
`.50,
`90.;
`-00:
`81.0 70.0 08.0 05.5 60.5 73.5
`H(HPO)n-H
`I
`.30,
`99..
`-80:
`77.0 72.6 70.5 07.0 68.5 77.0
`C7110-{PO}-'i-H
`2
`.30,
`99.:
`-60>
`78.0 74.5 71.5 720 73.0 30.5
`clrtzotP0.‘v\-CH:
`3
`.39,
`99¢
`-60>
`34.0 02.0 am am 06.0 90<
`ctecootaoin-coctn
`4
`.59,
`994
`-60:
`03.0 80.0 60.0 90¢ 90¢
`90¢
`ctb0c00tP0)rvc00ciu
`5
`lrtsoi
`lnsoi
`-00>
`77.5 74.0 71.5 73.5 00.0 90<
`cH:GiEO)n-CH3
`0
`.30,
`3;
`-24
`79.0 70.5 73.0 74.0 75.5 90-:
`craoteoruo-mica:
`7
`.503.
`54
`-80>
`74.0 70.0 60.0 67.5 70.0 75.0
`GH:otECr‘PO-575)-Ct-ta
`0
`.39,
`32
`-00>
`70.5 74.5 70.0 7i.0 7l.5 76.5
`cmo.lEorPo—3.fl'}n-CH:
`9
`.39,
`9.34
`-45
`54.0 44.0 39.0 -tt.0 45.0 55.0
`CHJO-[POIBO-7t‘3in-CH:
`I0
`no,
`99.;
`Insol
`_20.0
`Inset
`Inset
`Into! Inset inset
`ctamnoreo-srsin-ctt:
`ll
`.30,
`99..
`Insoi
`ll'|-50i
`Inset
`inset
`Inset Inset inset
`Cl-t-to-tB0)'>CHa
`12
` nttIu:|:
`HTR ;i-tlgh Tarrp. Region. LTR ; Low Temp. Region
`
`Page 5 of 9
`
`

`
`addition to the fluidity and solubility.
`
`3.1 THERMAL STABILITY
`The sealed tube tests were conducted for the evaluation
`
`Test conditions and results
`of thermal stabitity of PAGs.
`are shown in Table 4 and 5 respectively. The thermal
`stability of PACls are predominantly influenced by the
`chemical structure of end groups rather than components of
`the main chain. Ester and carbonate as and groups adversely
`affect the thermal stability of M03.
`
`Table 4. Sealed Tuba Tut
`
`
`Tharrnal Stability Test ttydrotyuo Stablity Teal
`
`Tarrporalura
`‘C1
`175
`mg
`id‘
`Time
`:1
`to
`in
`Oil
`c
`4
`4
`l-IFGt34a
`g
`1
`3
`W0
`n
`-
`o.e4
`
`Cal. Fa.Cu.AI ‘ Fa.Cu.Al
`
`
`
`
`Table 5. Thermal Stability or PA as In HFO134a
`
`
`Charnicaistructuro
`No.
`Total Acid No. Gas
`Appearance
`
`
`
`Cat. tncnomtOil Outbreak
`1
`H0tP0}~tt
`Good Good
`0.1:.
`none
`3
`3
`'
`.>
`HDDO
`2
`Egg:
`none
`5
`4
`Yelow Fa-Biadr
`none
`°“*°°'°4"°i'W°°“*
`0.1>
`3
`Yellow Good
`CO2
`‘JWCOGIFOHCOOCNJ
`0.»
`6
`°“'°tE°“°-SW4‘-“J Good Good'
`none
`
`
`°”’°‘E°"’°‘°”7"“°*‘“ Ge-eel Good 0.1»9 none
`
`
`
`Acetic acid and carbon dioxide were detected from
`
`thermally decomposed products of diester and dicarbonate
`capped PPGs respectively. As shown in following chemical
`equations.
`decomposed products such as acetic acid and
`carbon dioxide may be fonned by the pull reaction of
`hydrogen from tit
`carbon in the main chain of M63
`through the transition state of six membered ring structure
`formed by the internal hydrogen bond between hydrogen
`discribed above and oxygen of the carbonyl group in end
`groups 93.
`Dlester
`
`PAC 3
`
`
`.....t.5-..-::.*=.5I..-c..... .t-..g§;.-u]
`
`EH:
`
`Ha
`-*9 CH. COOH + H-CH-0"
`
`Dicarbonate Capped PAG
`
`cu. og—o—z:-cH~o~-
`
`H
`
`H:
`— H
`
`c+t.o—r.;::§tt-o-i
`
`
`
`---+
`
`cm on + co.
`
`CH.
`l + cit-ctt—o~
`
`
`
`
`
`
`
`region are plotted against monomer ratio of E0. P0 and
`B0 In Fig.6. Taking into account retrofit applications.
`PAG type lubricants should meet the required CST not only
`in Hi'~‘Cl34a but also in CFCl2. The composition of main
`chains of PACis applicable for both refrigerants are between
`in monomer ratio of P0 to E0.
`l0 to 0 and 7 to 3.
`
`Furthermore. these PAGs meet the required CST in a low
`temperature region as shown in Table 3.
`
`Ttmpontun
`
`('0)
`
`Oil Content (emit)
`
`Fig.5 influence at the Main Chains on can 0! MG:
`
`V
`
`.
`
`t._
`
`
`
`
`Tompcratururc) 8jjj
`
`
`llilliiillllllllllll
`Il.Il!fl_IIl_‘ I
`IIIHIIIIL =
`lllilllllliilllllll
`lllllllllllllllllll
`.
`i
`
`
`
`Ill
`llllllllllllll
`
`
`
`
`
`ll!
`
`P030
`F0
`logo
`EOIPOIBO Ratio
`
`I0
`
`Fig.8 influence of CST: In HFc134a and CF01:
`
`3. STABILITY OF PAGS IN HFCl34tt
`
`a high
`Refrigeration lubricants are exposed to
`temperature at the outlet of compressors due to the heat
`generation by the compression of the vapor of refrigerants.
`They are also attacked by water immersing into the system
`through rubber hoses equipped with low pressure area in the
`system.
`Furthermore.
`they
`have a possibility to be
`oxidized contacting with air at a seal of the drive shaft of
`the compressor. Therefore. refrigeration lubricants are
`required for the thermal stability and ltydrolytic stability in
`the presence of HFCi34a
`and oxidative stability.
`in
`
`Page 6 of 9
`
`

`
`made of iron in order to reduce the weight of the systems.
`Accordingly, the lubrication of sliding surfaces between iron
`and aluminum parts and also aluminum and aluminum parts
`became important.
`TCP (trycresyl phosphate) is commonly used as an
`antiwear agent for refrigeration lubricants. The influence of
`PAGs on the lubricity of TCP was evaluated using hermetic
`type friction tester in the presence of HFC l34a. All
`samples tested here were added lwt.% of TCP. The outline
`of the test apparatus and conditions are shown in Fig.7 and
`Table 8 respectively.
`The test results of load carrying capacities of these
`samples evaluated using aluminum pin and steel block are
`shown in Table 9. The antiwear property was evaluated
`using pin and block both made of aluminum.Tct€t
`results are
`shown in Table 10. Both test results indicate
`that the
`
`difference in end groups of PM}: noticeably influence the
`lubricity of TCP. Only diether capped FAG has a good
`compatibility with TC? and does not adversely. affect the
`lubricity of TCP. The components of main chains of PAGs
`did not influence the lubricity of 'l‘C'P.
`
`Table 0. Flux fut
`
`
`Load Carrying Capacity Wear
`I
`sit...
`antes...
`egress
`{mm
`mu
`3'0 upttt-tau:
`stun ecu)
`T!-no
`t_nin.] em
`10
`(
`Temperature
`C
`50
`59
`on
`
`g F
`
`ig.7 Hermetic Typo Falex Tester
`
`in}
`M.
`
`n
`
`3.2 HYDROLYTIC STABILITY
`The sealed tube tests in the presence of water were
`conducted for the evaluation of hydr-otytic stability of PAGs.
`‘lest conditions and results are shown in Table 4 and 6
`respectively. Ester or carbonate capped PAGs were easily
`hydrolyzed to produce polyglycols and related acids. These
`acids considered to com)-de iron and copper wires added to
`simulate the deterioration of materials contacting with
`refrigeration lubricants in the system. PAGs having ether
`or hydroxyl group as end groups had excellent hydrolytic
`stability as predicted.
`
`Table 6. fiydmlyilc Silblilly of P116! in HFC I84!
`..___..._......_...._......_.....___....._......_....__,
`Chemical Structure_ .
`2°-marines
`Total Add No. Gas
`.
`-
`Oil
`Oat.
`.'.tn9rom:. Qnbreait
`————*fl———H#Mfi———u—u————~———————___.__
`H0190)-us
`Good Good
`0.1»
`.
`. none
`C*b€HP0ivHi
`Good Good
`0.1»
`none
`CHIO-(POM-CH1
`Good Good
`0.1:
`none
`5 cmwwfi
`Brown Fe-Black
`24
`none
`i"°¥t°°°CHt
`Brown Good
`on
`CO2
`gibC>{EOrP0-stilt!-Cit:
`good
`good
`OJ,
`mm
`“’°l‘°"’°‘°"’l"*°"' Good Good
`0.t>
`none
`
`3.3 OXIDATIVE STABILITY
`
`Rotary bomb oxidation test was conducted to evaluate
`the oxidative stability of PAGs at
`120 C. All PAOS
`without antioxidant were easily oxidized. There were no
`differences in the oxidative stability between samples as
`shown in Table 7. This indicates that it is difficult to
`
`improve the oxidative stability of l’AGs as modifying these
`chemical structure. However. the addition of antioxidants
`
`dramatically improves the oxidative stability of PAGs
`enough to be in practical use.
`
`Tab]: 7. Oxldstlve Stability of FAG: In HFO134a
`______
`Chemical Structure
`Rotary B-omb oxtuauon Tent (min-i
`am we
`es.-at’ mum at OBI-‘G
`lfl
`IN
`Tfl
`#5
`i.‘Mr0-(‘POM-Oth
`TN
`¢lt:OC-O0-i".0lfl~000cH:
`rer
`WflfiUKHWWW
`Ml
` Oh
`
`Tut Gernitio-1:012-tt'c . OU*.509..|.hL2:I0*PI
`
`no-u>c>y-rt-t
`Cl'b0(P0h-ll
`
`3333332.’
`
`4. LUBRICATING CHALATERRISTICS OF
`
`4.1 COMPATIBILYFY WITH TCP
`The various kinds of materials such as iron, aluminum
`and copper are utilized as frictional parts of compressors in
`mobile air conditioning systems. The demand for improved
`fuel efficiency of automobiles have been encouraging the
`introduction of aluminum parts
`instead of machine pans
`
`Page 7 of 9
`
`

`
`Table 9. Load Carrying Capacity or PA Ge
`
`No.
`
`Chemical Structure
`
`Seizure Load
`{N}
`
`H0tPOln-H
`CH¢0ii’0}0+i
`CHIO-(PO)rt-OH:
`cl~IecOO»{PO)n-0001-ta
`0HsOCO0-{PO)n-GOOGHt
`
`1780
`1
`2230
`2
`5340
`3
`1 730
`4
`1 733
`5
`5340
`9
`
`
` 1
`
`
`Table 12. Fatigue Life of Mac
` '
`
`
`
`No.
`
`Chemical Structure
`
`t,,(xto- rev.)
`
`2
`3
`at
`5
`8
`9
`rel
`
`HO—(PO)n-H
`CH:-0~{PO)n»H
`cwwo(
`CHaODOO-(PO)ovCO0Ci-It
`CH:O-(EOIPO-5I'5}n-Cl-is
`cttso-(I-:OrP&3mn—CHt
`l»iltterIlOI(10rrtt'tt*fI@iO0'C)
`
`6.1
`8.1
`13';
`.
`6,5
`13_2
`123
`143
`
`
`
`
`
`Wear [mg]
`Chamlcai StructureNo. Pm mock
`1
`PO)n-H
`11.0
`18.9
`2
`Gist-(t?-(P0}rvH
`9.7
`24.8
`3
`CHavO-{PO}n-CH:
`0.1
`0,1
`4
`Cl~isGOO-[PO)t't~OOGHa
`8.9
`20,1
`5
`CHe0GO0{PO)n-OOOCI-b
`8.5
`231
`e
`CH:O~{EG‘P0-5/6)!)-CH:
`0.3
`0,1
`
`0.6Ci-I10-{EOfPO-3I7)n-CH:9 0,3
`
`
`
`4.2 INFLUENCE ON ROLLING FATIGUE
`
`The rolling bearings are insulted as one of the machine
`parts for the lubrication more in mobile air conditioning
`systems with Hi’-'Cl34a than these with CFCl2. The
`
`machine failure due to the flaking occurring on rolling
`surfaces ofthese bearings has been recently reported 5“. The
`influence of PAGs on the rolling fatigue life was evaluated
`using test apparatus shown in Fig.8, which was modified to
`be able to conduct the fatigue test under the circumstance of
`the vapor or I-iFCl34a. The test condition and results are
`shown in Table ii and 12 respectively. The test result of
`mineral oil type refiigeration lubricant obtained in the vapor
`of CFCIZ was also shown in ‘liable ll as a reference.
`It is clarified that the increase of hydroxyl groups
`decreases the fatigue life of PAGs from the test results of
`PPG(diol), monoetlter capped PPG(mon_ool) and diether
`capped PPG.
`In order to achieve almost the same fatigue
`life as mineral oil based refrigeration lubricants used for
`CFCI2. the ether is the most effective end group comparing
`with ester or carbonate. Furthermore.
`the difference in
`composition of the main chain does not affect the rolling
`fatigue life of PAGS.
`3
`
`.
`-
`Table 11. Fatigue urn Test __
` -
`BALL
`SUJ2
`. .
`D|SG
`SUJ2
`tatgsmm
`[(399)
`Pmax
`5.9
`Contact Round [rav./m rt.)
`2700
`Temperature
`80
`cc
`OH
`15o
`tlh
`Hi-'O134a
`0.5
` n:——
`
`s
`
`
`
`Fig.8 Fatigue Lite Tester
`
`
`
`5. SUMMARY AND CONCLUSIONS
`
`In order to clarify the relationship between the
`chemicai
`structure of PAG and the performance
`characteristics as the refrigeration lubricants used for
`I-lFC134e, performance tests were conducted using PAGs
`with different end groups and alkylene oxide chains in the
`presence of HFC134a. The summary and conclusions
`obtained from these testresults are as follows:
`
`(1) Diether capped PAGs having more than 50 mol.% PO
`to less than 50 mol.% E0, or more than 70 moi.% PO
`to less than 30 moiflla B0 as a monomer ratio meet
`
`the guide line of the specifications for fluidity
`characteristics taking into account both the pour point
`and viscosity-temperature characteristics.
`(2) The main factor to control the solubility of PAGs is the
`composition of the main chain. The monomer ratio
`applicable for both I-£FCl34a and Cl’-‘C12 are more than
`70 mol.% PO to less than 30 mol.% E0.
`
`(3) The lubricity. thermal stability and hydrolytic stability
`of PAGS are pwrninantly influenced by the difference
`in end groups. Diether capped PAGS are the most
`preferable of all PAGS tested.
`
`
`
`Page 8 of 9
`
`

`
`(4) All PAGs tested were easily oxidizodregurdless of me
`chemical sIIucLure.'I'herefore, addition of antioxidants
`are necessary to bein practical use.
`(5) From these test results. it was clarified that dimethyl
`cine: capped PAGs with a monomer ratio of more than
`10 mol.% PO to less than so mm, so in the main
`
`suitable performance
`chain showed the most
`characteristics of all PAGS tested. Newly developed
`mfrigcrafion lubricants using these PAGs have been
`successfully introduced Into the market for mobile air
`conditloning systems with Hf-‘Cl34a.
`
`REFERENCES
`
`[1] William LBrown. SAE Paper No.932904.
`[2] A.M.Smith. M.C.Beggs. and B.D.Greig.,SAE Paper
`No.930292.
`
`[3] T.Migila,Inuoduc1ion of Organic Chemistry,
`Reaction and Mechanism..pl74
`[4] Kazuhiko Saw eIa1.TrlboIogisl.37,l1(l992)9l8-922
`
`Page 9 of 9