Oil miscible polyalkylene glycols and uses thereof

Abstract

A polyalkylene glycol having an end-group of the general formula: ##STR00001## in which each R.sup.2 independently represents a hydroxyl, alkyl, alkenyl, aryl, heteroaryl, benzyl, or polyalkylene glycol group, and each R.sup.3 independently represents a hydroxyl, alkyl, alkenyl, aryl, heteroaryl, benzyl, or polyalkylene glycol group; m is 0, 1, 2, 3, 4, 5 or 6; and n is 0, 1, 2 or 3. A lubricating oil composition comprising this polyalkylene glycol. A refrigerant composition comprising this polyalkylene glycol. A method of lubricating moving parts of an industrial or automotive system comprising applying a composition to the parts, wherein the composition comprises this polyalkylene glycol.

Claims

1. A polyalkylene glycol containing at least 4 alkylene glycol units and having an end-group of the general formula: ##STR00004## in which m is 2; and one R.sup.2 represents a methyl group and the other R.sup.2 represents a C.sub.12-20 alkyl group; each R.sup.3 independently represents a hydroxyl, alkyl, alkenyl, aryl, heteroaryl, benzyl, or polyalkylene glycol group; and n is 0, 1, 2 or 3.

2. The polyalkylene glycol as claimed in claim 1, which has the general formula:
R[(C.sub.xH.sub.2xO).sub.p(C.sub.yH.sub.2yO).sub.q(C.sub.zH.sub.2zO).sub.r]R.sup.1  (II) wherein R is the group of formula I; R.sup.1 is a hydrogen atom, a C.sub.1-20 alkyl group or a C.sub.1-20 acyl group, or a group of formula I; x is 2; y is 3; and z is an integer from 4 to 8; and each of p, q and r independently is a number from 0 to 350, provided that the total of p, q and r is at least 4.

3. The polyalkylene glycol as claimed in claim 1, in which the number of alkylene oxide monomer units having 4 or more carbon atoms is 0.

4. The polyalkylene glycol as claimed in claim 1, in which the number of alkylene oxide monomer units having 2 carbon atoms is 0.

5. The polyalkylene glycol as claimed in claim 1, in which the number of alkylene oxide monomer units having 3 carbon atoms is from 4 to 50.

6. The polyalkylene glycol as claimed in claim 1, in which one end group of the formula I is present, and the or each other end group is H.

7. The polyalkylene glycol as claimed in claim 1, in which n is 1, 2 or 3 and each R.sup.3 is a methyl group.

8. The polyethylene glycol as claimed in claim 1, in which the end group of formula I is derived from a tocopherol.

9. A lubricating oil composition comprising the polyalkylene glycol as claimed in claim 1.

10. The lubricating oil composition as claimed in claim 9, which comprises one or more known additives selected from the group consisting of those that provide improved antiwear properties, extreme pressure resistance, oxidation stability, corrosion inhibition, antifoaming, suppression of pourpoint, improvement of viscosity index, and reduction of acid content.

11. The lubricating oil composition as claimed in claim 9, which also contains another lubricating oil.

12. The lubricating oil composition as claimed in claim 9, which has a kinematic viscosity in the range of from 10 to 430 cSt at 40° C., a flashpoint of at least 260° C., and/or a pourpoint of at least −10° C.

13. A refrigerant composition which comprises a refrigerant together with a polyalkylene glycol as claimed in claim 1.

14. A refrigeration system which comprises a refrigerant composition as claimed in claim 13.

15. The refrigeration system as claimed in claim 14, which includes a compressor in which said refrigerant composition is present.

16. A method of lubricating moving parts of an industrial or automotive system, which comprises applying to said moving parts the polyalkylene glycol as claimed in claim 1.

17. A method of servicing an industrial or automotive system, which comprises adding the polyalkylene glycol as claimed in claim 1.

18. The polyalkylene glycol as claimed in claim 1, wherein said polyalkylene glycol is fully miscible with mineral oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1, 2 and 3 show the results of testing carried out as described in the Examples herein.

(2) FIG. 1 shows the miscibility of comparative PAGs with refrigerant R407C.

(3) FIG. 2 shows the miscibility of the product 10TP of Invention Example 1 with refrigerant R407C.

(4) FIG. 3 shows the miscibility of the product 20TP of Invention Example 2 with refrigerant R407C.

(5) The following Examples illustrate the invention.

EXAMPLES

(6) Comparison Products

(7) The miscibility of PAGs according to the invention was compared with miscibility of commercially available PAGs developed and marketed specifically as “oil soluble” polyalkylene glycols for a variety of industrial applications, and also PAGs developed and marketed specifically for refrigeration systems, which are generally not regarded as being “oil soluble”. Sample PAG composition was determined using 1H and 13C NMR as solutions in CDCl.sub.3. Spectra were acquired at ambient temperature on a Bruker DPX400 NMR spectrometer operating at 400.13 MHz for 1H (MT/CMS/20).

(8) The following comparative examples were utilized in the testing:

(9) TABLE-US-00002 TABLE 2 Oil Soluble Comparison PAG Oil Soluble Comparison PAG Type A Type B ISO Viscosity Grade (cSt at 40° C.) 32 46 68 220 22 100 Pag Initiator type (R) Linear C12 Linear C12 Linear C12 Linear C12 Linear & Linear & alcohol alcohol alcohol alcohol branched branched C16-C17 C12-C15 alcohol alcohol Ethylene Oxide (wt %) (C2H4O) 0 0 0 0 0 0 Propylene Oxide (wt %) (C3H6O) 48.8 43.1 49.9 49.8 100 100 Butylene Oxide (wt %) (C4H8O) 51.2 56.9 50.1 50.2 0 0 Terminating Species (R1) —OH —OH —OH —OH —OH —OH Oxide arrangement random random random random — — Number average molecular 780 1010 1260 2790 477 1775 weight, Mn Refrigeration Refrigeration Refrigeration Comparison Comparison Comparison PAG Type C PAG Type PAG Type (dicapped D (uncapped E (uncapped PAG) PAG) PAG) ISO Viscosity Grade (cSt at 40° C.) 46 150 46 150 46 150 Pag Initiator type (R) Tetrahydro- Tetrahydro- Butanol Butanol Butanol Butanol furfuryl furfuryl alcohol alcohol Ethylene Oxide (wt %) (C2H4O) 0 0 0 0 50 50 Propylene Oxide (wt %) (C3H6O) 100 100 100 100 50 50 Butylene Oxide (wt %) (C4H8O) 0 0 0 0 0 0 Terminating Species (R1) —CH3 —CH3 —OH —OH —OH —OH Oxide arrangement — — — — random random Number average molecular 1050 1880 1005 1800 1000 2000 weight, Mn

(10) where Type A=Dow marketed Oil Soluble PAGs, Type B=Sasol marketed Oil Soluble PAGs, Type C=Shrieve marketed dicapped RFL Refrigeration PAG, Type D=Shrieve marketed single end-capped water insoluble Zerol PAG, Type E=Shrieve marketed single end-capped water soluble Zerol PAG.

(11) Physical property data determined for comparative samples as follows:

(12) TABLE-US-00003 TABLE 3 Comparison Comparison Comparison Comparison Comparison Property Test Method PAG Type A PAG Type B PAG Type C PAG Type D PAG Type E PAG ISO Viscosity Grade 46 220 22 100 46 150 46 150 46 150 Viscosity at 40° C., cSt ASTM D445 49.4 211.2 20 79.4 47.7 157.4 44.2 131.3 51 139.6 Viscosity at 100° C., cSt ASTM D445 8.7 31.7 4.17 14.2 9.9 28.7 8.8 28 10.8 27 Viscosity Index ASTM D2270 159.8 194.5 110.9 186.3 201.9 222.9 183.5 251.8 209.4 231.4 Pourpoint, ° C. ASTM D97 <−45 −40 −40 −45 <−45 −40 <−45 −40 <−40 −40 Flashpoint (COC), ° C. ASTM D92 238 245 211 232 257 248 220 234 250 268 4-ball wear scar (mm) ASTM D 4172 0.59 0.42 0.61 0.46 0.57 0.61 0.46 0.48 0.55 0.52 Falex failure load (lb) ASTM D3233 500 750 500 750 1000 1000 1000 1000 750 1250
Measurement of Miscibility

(13) Measurement of miscibility was performed in accordance with the principles of Ashrae 86, in which the blend of mineral oil and test lubricant is prepared and sealed in a sealed glass tube. The temperature of the tube is lowered in 10° C. increments from ambient temperature, to a minimum of −40° C., before warming in 10° C. increments to +60° C. before returning to ambient. For each incremental temperature the sealed glass tube is maintained at that temperature for a period of one hour to observe miscibility, if significant changes in miscibility are observed the temperature increment is reduced to 5° C.

(14) Typical properties of the mineral oils utilized in the miscibility testing are as follows:

(15) TABLE-US-00004 TABLE 4 SN150 L150 Property Test Method Paraffinic Naphthenic ISO Viscosity Grade 32 32 Viscosity at 40° C., cSt at ASTM D445 30.0 30.1 40° C. Viscosity at 100° C., cSt at ASTM D445 5.1 4.5 40° C. Viscosity Index ASTM D2270 56.5 22.9 Flashpoint (COC), ° C. ASTM D92 208 182 API Gravity at 35° C. ASTM D1250 31.8 24.2 Total Acid Number, ASTM D974 0.02 0.01 mgKOH/g Molecular Weight, g/mol ASTM D2502 393 123 Pourpoint, ° C. ASTM D5950 −15 −43

(16) Miscibility data was obtained for the combinations of mineral oil and comparative polyalkylene glycol grades as shown:

(17) TABLE-US-00005 TABLE 5 Paraffinic Mineral Oil Miscibility with Comparative PAGs Lubricant composition (wt % Par- affinic Comparable PAG Product Grades SN150 Type A Type A Type A Type C Type B Type B Type E Type E Type D Type D MO VG220 VG46 VG68 VG46 VG32 VG100 VG50 VG150 VG50 VG50 Observations Conclusion 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible 20 to 60° C., Fail cloudy −40 to −20° C., Stridations −10 to −10° C. 80 20 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C., Fail Cloudy −40 to −20° C. 20 80 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C., Fail Cloudy −40 to −20° C. 20 80 Miscible −40 to 60° C. Pass 80 20 2 Phase −40 to 10° C., Fail Miscible 20 to 60° C. 20 80 Miscible −40 to 60° C. Pass 80 20 2 phase from −40 to 60 degC. Fail 80 20 2 phase from −40 to 60 degC. Fail 80 20 2 phase −40 to 10° C., Fail Miscible 20 to 60° C. 20 80 Miscible −40 to 60° C. Pass 80 20 2 phase from −40 to 60 degC. Fail 20 80 Miscible −40 to 60° C., Fail Cloudy −40 to −20° C. 50 50 Miscible −40 to 60° C., Fail Cloudy −40 to −20° C. 80 20 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C., Fail Cloudy −40 to −20° C. 50 50 Miscible 20 to 60° C., Fail Cloudy −40 to −20° C., Stridations −10 to −10° C. 80 20 Miscible −40 to 60° C. Pass

(18) TABLE-US-00006 TABLE 6 Naphthenic Mineral Oil Miscibility with Comparative PAGs Lubricant composition (wt % Type A Type A Type C Type B Type B Naphthenic L150 MO VG220 VG48 VG46 VG32 VG100 Observations Conclusion 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C., hazy at −40 Fail to −20° C. 50 50 Miscible −40 to 60° C., hazy at −40 Fail to −30° C. 80 20 Miscible −40 to 60° C., hazy at −40° C. Fail 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass

(19) FIG. 1 shows the miscibility of the various comparative PAGs with refrigerant R407C.

(20) The criteria required for full mineral oil/polyalkylene glycol miscibility was complete homogeneity of the mixture across the temperature range of test −40° C. to +60° C. Phase separation, cloudiness, haze and striations are indicative of incomplete homogeneity. Results demonstrate a lack of comprehensive mineral oil miscibility across the paraffinic/naphthenic mineral oil types, temperature range of test, and ratios of mineral oil:PAG for the comparative types tested.

INVENTION EXAMPLES

Example 1

10 Mole Tocopherol Propoxylate (Sample “10TP)

(21) In a first step, 213 g of Mixed Tocopherol (commercially available as Mixed Tocopherol, ex-J Edwards International Inc) was dried to a moisture level <10 ppm, and catalysed with solid potassium hydroxide to a dosage of 0.125 wt % in the final product. The catalysed material was dried to 0.01 wt % water content and reacted with 287 g of propylene oxide at 135° C. until pressure line-out in the reaction vessel indicated reaction completion. The catalyst was thereafter removed from the product prior to sample testing. The resulting product contained 10 propylene oxide units per molecule.

Example 2

20 Mole Tocopherol Propoxylate (Sample “20TP)

(22) In a first step 200 g of product from Example 1, prior to catalyst removal, was reacted with 115 g of propylene oxide at 135° C. until pressure line-out in the reaction vessel indicated reaction completion. The catalyst was thereafter removed from the product prior to sample testing. The resulting product contained 20 propylene oxide units per molecule.

Example 3

Testing of the Products of Examples 1 and 2

(23) The properties of the products of Examples 1 and 2 were measured using standard industry testing methods. Miscibility was measured as described above. Table 7 shows the basic physical properties. Table 8 shows the mineral oil compatibility of the products. Table 9 shows the minimum quantity of the products of Invention Examples 1 and 2 required to solubilize 90/10 (wt/wt) comparative PAGs D and E and mineral oils. FIGS. 2 and 3 show the miscibility of the products of Invention Examples 1 and 2 with refrigerant R407C.

(24) TABLE-US-00007 TABLE 7 Basic physical properties of Invention Examples 1 and 2 Example 1: Example 2: 10 mole 20 mole Tocopherol Tocopherol Propoxylate Propoxylate Property Test Method (10TP) (20TP) PAG ISO Viscosity Grade 200 200 Viscosity at 40° C., cSt ASTM D445 194.5 204 Viscosity at 100° C., cSt ASTM D445 17.8 22.4 Viscosity Index ASTM D2270 99.4 134.1 Pourpoint, ° C. ASTM D97 −28 −32 Flashpoint (COC), ° C. ASTM D92 302 293 4-ball wear scar (mm) ASTM D 4172 0.47 0.44 Falex failure load (lb) ASTM D3233 750 750

(25) TABLE-US-00008 TABLE 8 Mineral Oil miscibility for Invention Examples 1 and 2 Lubricant composition (wt % Invention Examples Example 1: Example 2: Con- Mineral Oil “10TP” “20TP” Observations clusion Paraffinic SN150 MO 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass Naphthenic L150 MO 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass 20 80 Miscible −40 to 60° C. Pass 50 50 Miscible −40 to 60° C. Pass 80 20 Miscible −40 to 60° C. Pass

(26) TABLE-US-00009 TABLE 9 Minimum % invention required to solubilize 90/10 (wt/wt) Comparative PAGs D and E/Mineral Oils. Lubricant composition (wt % Comparative Samples Comparative Comparative Invention Examples PAG Type E PAG Type D invention Example: Mineral Oil VG150 VG150 Tocopherol Propoxylate Observations Conclusion Paraffinic SN150 MO 10.0 90.0 immiscible at room temperature Fail 7.5 67.5 25.0 Miscible −40 to 60° C. Pass 10.0 90.0 immiscible at room temperature Fail 9.9 89.1 1.0 Miscible −40 to 60° C. Pass Naphthenic L150 MO 10.0 90.0 immiscible at room temperature Fail 8.5 76.5 15.0 Miscible −40 to 60° C. Pass 10.0 90.0 immiscible at room temperature Fail 9.9 89.1 1.0 Miscible −40 to 60° C. Pass
The above data illustrate the following:

(27) Comparison of Table 3 and Table 7 confirms no disadvantage of products of the invention with respect to inherent properties expected of polyalkylene glycols. Further improvement of the Viscosity Index would be expected simply by increasing the number of propylene oxide units included in the products.

(28) Comparison of Table 4 and Table 7 confirms the advantage of the products of the invention with respect to improvement of Viscosity Index for mineral oil derived products in admixture with products of the invention.

(29) Comparison of Table 5 and Table 6 with Table 8 provides confirmation that the mineral oil miscibility properties of the invention are advantageous, with respect to prior art in this field, with a complete absence of any inhomogeneity demonstrated with either naphthenic or paraffinic mineral oils in all ratios and across the full temperature range of test.

(30) Table 9 demonstrates that utilization of a minimum concentration of the novel polyether of 1.0% wt in a typical oil-immiscible polyalkylene glycol, enables mineral oil compatibility to be imparted to the blend.

(31) Under normal operating conditions the oil circulation rate (OCR) in refrigeration circuits is around 1% in 99% of refrigerant. Towards end of system lifetime where component tolerances become reduced this may increase to around 2-5% oil in refrigerant. Miscibility of lubricant with refrigerant is most desirable in the temperature region of 15/20° C.-60° C. for effective system operation. FIGS. 1, 2 and 3 demonstrate that there is an advantageous impact on the miscibility property with R407C under these lubricant concentration and system temperature conditions for the novel polyethers of the invention, therefore demonstrating superior suitability for use in refrigeration systems R407C systems, which are typically those retrofitted from R22, where residual mineral oil may be present and where the oil solubility properties of the novel polyether are similarly advantageous.

(32) The above results clearly demonstrate that the products of the present invention have advantageous properties making them particularly suitable for use in refrigeration applications where temperature extremes are commonly encountered. Specifically, they are fully miscible with both paraffinic and naphthenic mineral oil. Moreover, they impart miscibility with mineral oils to blends including known PAGs, when those known PAGs are not themselves miscible with mineral oil. Further, they are fully miscible with HFC type refrigerants (typified by R407C), unlike for example the PAGs of WO 01/57164 (comparative PAG Type C). This can all be achieved in economic fashion without incorporating C4+ alkylene oxide units.

(33) The foregoing has outlined the features and technical advantages of the present invention. It will be appreciated by those skilled in the art that the embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.