Use of re-refined base oil

Abstract

The present invention provides the use of a re-refined base oil in an industrial lubricating fluid, said industrial lubricating fluid comprising at least one base oil and at least one additive, in order to improve one or more of oxidation stability and low temperature performance of said industrial lubricating fluid.

Description

[0001] SP2908 - 1 - USE OF RE-REFINED BASE OIL Field of the Invention 5 The present invention relates to the use of re- refined base oils in industrial lubricant oil formulations. Background of the Invention Lubricating fluids are required in all industrial 10 equipment with moving parts. Industrial lubricating fluids, therefore, include hydraulic oils, gear oils, compressor oils, circulating oils and turbine oils, etc. Such industrial lubricating fluids generally comprise one or more base oils and one or more additives. Typically, 15 the additive treat rate for industrial lubricating fluids is considerably lower than for engine oils, with additive treat rates of less than 5wt% being usual. With such a low additive treat rate, the base oil being used is of key importance. Typically, so called 20 ‘virgin’ base oils are used in the manufacture of industrial lubricating fluids. These are typically produced from crude oil or natural gas, directly via refining or via synthetic processes. The disposal of used lubricating fluids requires 25 careful processing and waste streams are often used as burner fuel. In all technology areas, it is necessary to consider the carbon footprint of a product and to try and ensure that raw materials are re-used and recycled where possible. This has led to the development of so called 30 “re-refined base oils”. Re-refined base oils (RRBOs) are base oils derived from reprocessing of used lubricating oils to remove contaminants, oxidized products, and additives. Technologies such as distillation, thermal de- asphalting, or solvent (often propane) de-asphalting are used as recycling technologies for used lubricating fluids. The intermediate products created by recycling 5 technologies are unfinished and typically unsuited for use as lubricants without further improvement. Finishing technologies such as clay treatment, hydrotreatment (see, for example, EP3921390A1, US11034895B1), or solvent extraction (as described in CN107574012A may then be used 10 to “finish” the quality of the intermediates into marketable base oils. When a recycling technology and a finishing technology are coupled together, they are generally referred to as a re-refining technology. A further, pre-treatment, step may also be used to remove 15 sludge, water and additive metals before recycling occurs. Previously, re-refined base oils have been viewed as inferior in quality to virgin base oils. With the development of improved re-refining technologies this is no longer the case. However, the focus on re-refining 20 technologies and the re-refined base oil thus produced has focused on producing and using base oils of sufficient quality that they can pass the standards set for lubricating oils across industrial technologies (see, for example, CN104673460A and CN104673461A). It is the 25 intention of the present inventors to develop improved lubricating oils using RRBOs. Summary of the Invention The present invention therefore provides the use of a re-refined base oil in an industrial lubricating fluid, 30 said industrial lubricating fluid comprising at least one base oil and at least one additive, in order to improve one or more of oxidation stability and low temperature performance of said industrial lubricating fluid. Detailed Description of the Invention One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed 5 techniques. Additionally, in an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described in the specification. When introducing elements of various embodiments of 10 the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 15 Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 20 The present inventors have surprisingly found that re-refined base oils may be used in order to provide improved fluids for use as industrial lubricating fluids. Industrial lubricating fluids include, but are not limited to, those used as hydraulic oils, gear oils, 25 compressor oils, circulating oils and turbine oils. An industrial lubricating fluid according to the present invention comprises at least one base oil and at least one additive. The industrial lubricating fluid preferably 30 comprises at least 95wt% of base oil. According to the invention, of this base oil, at least a portion and up to 100wt% is re-refined base oil. Preferably at least 10wt% of the base oil in the industrial lubricating fluid is re- refined base oil. Depending on the viscosity grades of industrial lubricating fluid, RRBO treat rates could be as high as almost 100% for the light grades of industrial lubricating fluid while heavy virgin base oils might be needed to close the viscosity gap for heavy grades of 5 industrial lubricating fluid. Base oil in the industrial lubricating fluid that is not re-refined base oil may be any suitable base oil typically used in a lubricating fluid. Specific examples include base oils belonging to Groups I to IV of the API 10 (American Petroleum Institute – see Table 1) base oil categories, which can be used alone or in a mixture. Table 1 – API base oil categories Category Sulfur Saturates Viscosity (%) (%) index Group I >0.03 and / or <90 80 - <120 Group II ≤0.03 and ≥90 80 - <120 Group III ≤0.03 and ≥90 ≥120 Group IV PAO Synthetic Lubricants Group V All other base oils The re-refined base oil used in the present 15 invention is preferably Group I or Group II according to the API base oil categories. More preferably, the re- refined base oil used in the present invention is Group I according to the API base oil categories. Typical re- refined Group I base oils, while falling within the API 20 categorisation for Group I base oils have features not typical for a virgin Group I base oil. Preferably, the saturates content of the Group I re-refined base oil is preferably at least 80%, more preferably at least 90%. The viscosity index of the Group I re-refined base oil is 25 preferably at least 95 and more preferably at least105. The sulphur content of the Group I re-refined base oil is preferably no more than 0.3% and more preferably no more than 0.1%. The sulphur content of the Group I re-refined base oil is greater than 0.03%, in line with the API classification. The re-refined base oil use in the present invention is preferably base oil that has been recycled from used 5 lubricant fluid using solvent extraction or hydrotreatment. Preferably the overall amount of additives in the industrial lubricating fluid is less than 5wt%, more preferably less than 3wt%, even more preferably less than 10 2wt% based on the overall weight of the industrial lubricating fluid. Suitably, the overall amount of additives in the industrial lubricating fluid is at least 0.1wt% based on the overall weight of the industrial lubricating fluid. The additives may be incorporated into 15 the industrial lubricating fluid singly or as part of one or more additive packages. Whether added singly or in additive packages, a diluent oil may be included with the additive and form part of the finished industrial lubricating fluid. 20 Different types of additives will be suitable depending on the end use of the industrial lubricating fluid. These include, but are not limited to anti-wear additives, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, anti- 25 oxidants, rust and corrosion inhibitors, dispersants, demulsifiers and foam inhibitors. Anti-wear additives and extreme pressure additives include phosphorus compounds, such as phosphate esters, acidic phosphate esters, amine salts of acidic phosphate 30 esters, basic phosphate esters, phosphite esters, phosphorothionates, zinc dithiophosphates, esters of dithiophosphoric acid and alkanols or polyether-type alcohols, and derivatives thereof, phosphorus-containing carboxylic acids and phosphorus-containing carboxylic acid esters. As examples of viscosity-index improvers mention may be made of non-dispersant type viscosity-index improvers 5 such as polymethacrylates and olefin polymers such as ethylene-propylene copolymers, styrene-diene copolymers, polyisobutylene and polystyrene, and dispersant type viscosity-index improvers where nitrogen-containing monomers have been copolymerised with these, and they may 10 be made with kinds different from the copolymers of olefins and alkyl methacrylates. As examples of pour-point depressants mention may be made of polymethacrylate-based polymers. Suitable antioxidants include amine-based 15 antioxidants, sulphur-based antioxidants, phenol-based antioxidants and phosphorus-based antioxidants. These antioxidants may be used singly or in combination. As examples of demulsifiers suitable for use in industrial lubricating fluids according to this invention, 20 mention may be made of those in the known art normally used as additives for lubricating oils. Defoaming agents may also be added in order to impart defoaming characteristics to the lubricating oil composition of this invention. 25 As examples of defoaming agents suitable for use in industrial lubricating fluids according to this invention, mention may be made of organosilicates such as dimethylpolysiloxane, diethylsilicate and fluorosilicone, and non-silicone type defoaming agents such as 30 polyalkylacrylates. The present invention will now be illustrated through the following, non-limiting examples. Examples A range of industrial lubricant formulation were blended and tested as set out in Tables 3 to 6. The following base oils (with properties as set out in Table 2) were used in the Examples. The Group I 150SN & 500SN are commercially available from Hindustan Petroleum Corporation Limited (HPCL) under the brand name of Alprol N32 & Alprol N100. The Group II 150N & 500N are commercially available from Hainan Handi Sunshine Petrochemical Co. under the brand name of HDS-150N & HDS-500N. The Group I RRBO 150SN is commercially available from Hebei Jingu Recycling Resources Development Co. under the brand name of JINGU 150SN. The Group II RRBO 150N is commercially available from Changzhou FINAS Energy Technology Co. under the brand name of FINAS 150N. Table 2 HANDI HANDI HPCL HPCL SUNS JINGU FINAS PropertiesmTeetshtH SUNSH od150SN 500SN INE INE RRBO RRBO 150N 500N 150SN 150N Vk @ 100°C ASTM (cSt)D4455.293 10.67 5.386 10.13 5.492 5.318Vk @ 40°C ASTM (cSt)D44531.56 93.54 31.54 82.61 31.27 28.97Viscosity ASTM IndexD227098 97 104 103 112 118Saturates IP (%) 368 / ASTM 74.4 61.5 99.8 99.8 96.6 97 D7419 Sulphur ASTM content (%)30.0.000 0.000 0.047 0.007 D54597 1.381 2 7 7 The hydraulic oil package used in the formulations is a commercially available standard industrial hydraulic oil additive package. The pour point depressant used in the formulations is a standard, commercially available, pour point depressant. The anti-foam additive used in the formulations is a commercially available anti-foam additive. It can be seen from Tables 3 to 6 that Group I or Group II RRBO based samples show performance advantages, 5 against their virgin base oil counterparts, like higher VI, lower viscosity at 0°C, better oxidation stability as reflected by RPVOT and TOST test outcomes.

[0002] Table 3 Comp Comp Ex. 1 Ex. 2 Ex 1 Ex 2 Group I 150SN 89.5 Group I 500SN 9.94 Group II 150N 95.47 Group II 500N 3.97 6.34 11.79 Group I RRBO 150SN 92.7 Group II RRBO 150N 87.7 Hydraulic oil package10.45 0.45 0.45 0.45Pour point depressant 2 0.1 0.1 0.5 0.05 Anti-foam additive 3 0.01 0.01 0.01 0.01 PropertiesmTeetshtodAppearance Visual B&C B&C B&C B&C Vk @ 40°C (cSt) GB / T 265 35.27 34.31 33.63 32.76 Vk @ 100°C (cSt) GB / T 265 5.751 5.760 5.843 5.762 Viscosity Index GB / T 1995 103 108 117 118 Vk @ 0°C (cSt) GB / T 265 383.0 346.3 317.3 304.7 Copper, 3 h, 100°C GB / T 5096 1b 1b 1a 1a Rust, SSW, Method B - No No No No24 HoursGB / T 11143Rustin Rustin Rustin Rustin g g g g Foaming Seq I, ml.ml GB / T 12579 0 / 0 30 / 0 10 / 0 50 / 0 Seq II, ml / ml 30 / 0 10 / 0 10 / 0 30 / 0 Seq III, ml / ml 0 / 0 0 / 0 10 / 0 50 / 0 water separation @54°CGB / T 7305 25 20 10 10TOST Oxidation Stability Total acid number GB / T 12581 after 1000hrs0.3 0.24 0.093 0.12RPVOT, 150°C (min) SH / T 0193 205 212 265 228 Filterability (Stage ISO 13357- I)-Dry (%)2:201784.7 88.6 96.3 94.2Filterability (StageII)-Dry (%)67.0 78.6 94.7 90.1Filterability (Stage ISO 13357- I)-Wet 1:2017 91.9 78.3 87.0 82.0 Filterability (StageII)-Wet83.9 54.9 79.0 64.0 Table 4 Comp Comp Ex.3 Ex. 4 Ex 3 Ex 4 Group I 150SN 29.83 Group I 500SN 69.61 Group II 150N 14.92 Group II 500N 84.52 69.04 74.49 Group I RRBO 150SN 30 Group II RRBO 150N 25 Hydraulic oil package10.45 0.45 0.45 0.45Pour point depressant 2 0.1 0.1 0.5 0.05 Anti-foam additive 3 0.01 0.01 0.01 0.01 PropertiesmTeetshtodAppearance Visual B&C B&C B&C B&C Vk @ 40°C (cSt) GB / T 265 67.2 68.31 65.92 68.01 Vk @ 100°C (cSt) GB / T 265 8.631 9.060 8.992 9.109 Viscosity Index GB / T 1995 99 107 111 109 Vk @ 0°C (cSt) GB / T 265 957.6 938.3 826.9 916.0 Copper, 3 h, 100°C GB / T 5096 1b 1b 1a 1a Rust, SSW, Method B - No No No No24 HoursGB / T 11143Rustin Rustin Rustin Rustin g g g g Foaming Seq I, ml.ml GB / T 12579 0 / 0 60 / 0 10 / 0 0 / 0 Seq II, ml / ml 60 / 0 30 / 0 20 / 0 30 / 0 Seq III, ml / ml 0 / 0 0 / 0 10 / 0 0 / 0 water separation @54°CGB / T 7305 30 20 15 10TOST Oxidation Stability Total acid number GB / T 12581 after 1000hrs0.25 0.19 0.10 0.17RPVOT, 150°C (min) SH / T 0193 173 215 202 208 Filterability (Stage ISO 13357- I)-Dry (%)2:201782.7 93.1 93.3 85Filterability (StageII)-Dry (%)65.7 86.0 86.5 74.5Filterability (Stage ISO 13357- I)-Wet 1:2017 92.5 80.5 88.0 83 Filterability (StageII)-Wet84.1 61.2 80.0 74 Table 5 Example 5 Example 6 Group I 150SN Group I 500SN Group II 150N Group II 500N 39.96 43.41 Group I RRBO 150SN 59.08 Group II RRBO 150N 56.08 Hydraulic oil package 1 0.45 0.45 Pour point depressant 2 0.5 0.05 Anti-foam additive 3 0.01 0.01 Properties Test method Appearance Visual B&C B&C Vk @ 40°C (cSt) GB / T 265 46.51 46.68 Vk @ 100°C (cSt) GB / T 265 7.170 7.204 Viscosity Index GB / T 1995 114 114 Vk @ 0°C (cSt) GB / T 265 517.9 509.2 Copper, 3 h, 100°C GB / T 5096 1a 1a Rust, SSW, Method B - 24GB / T 11143No NoHoursRusting Rusting Foaming Seq I, ml / ml GB / T 12579 10 / 0 0 / 0 Seq II, ml / ml 10 / 0 30 / 0 Seq III, ml / ml 10 / 0 0 / 0 water separation @ 54°C GB / T 7305 10 10 TOST Oxidation Stability Total acid number after GB / T 125811000hrs *mg KOH / g0.089 0.11RPVOT, 150°C (min) SH / T 0193 226 267 Filterability (Stage I)-Dry ISO 13357- (%)2:201796.5 87.5Filterability (Stage II)-Dry(%)93.1 76.6Filterability (Stage I)-WetI1S:O201137357-86 78 Filterability (Stage II)-Wet 76 58 Table 6 CompComp Ex Example 5Ex.6 7 Group I 150SN 64.41 Group I 500SN 34.63 36.67 Group II 150N 59.7 Group II 500N 39.79 Group I RRBO 150SN 62.37 Group II RRBO 150N Hydraulic oil package 1 0.45 0.45 0.45 Pour point depressant 2 0.5 0.05 0.5 Anti-foam additive 3 0.01 0.01 0.01 Properties Test method Appearance Visual B&C B&C B&C Vk @ 40°C (cSt) GB / T 265 46.20 45.11 46.52 Vk @ 100°C (cSt) GB / T 265 6.710 6.869 6.850 Viscosity Index GB / T 1995 97 108 102 Vk @ 0°C (cSt) GB / T 265 558.2 510.3 520.4 Copper, 3 h, 100°C GB / T 5096 1a 1a 1a Rust, SSW, Method B - 24GBNo No NoHours / T 11143Rusting Rusting Rusting Foaming Seq I, ml / ml GB / T 12579 0 / 0 0 / 0 0 / 0 Seq II, ml / ml 10 / 0 20 / 0 10 / 0 Seq III, ml / ml 0 / 0 0 / 0 0 / 0 water separation @ 54°C GB / T 7305 30 10 25 TOST Oxidation Stability Total acid number after GB / T 125811000hrs *mg KOH / g0.64 0.22 0.11RPVOT, 150°C (min) SH / T 0193 192 216 244 Filterability (Stage I)- ISO 13357- Dry (%)2:201795.8 94.6 96.3Filterability (StageII)-Dry (%)92.3 90.4 92.6Filterability (Stage I)- ISO 13357- Wet1:201764 82 88Filterability (Stage II)-Wet 20 67 74

Claims

SP2908 - 13 - C L A I M S 1. Use of a re-refined base oil in an industrial lubricating fluid, said industrial lubricating fluid comprising at least one base oil and at least one additive, in order to improve one or more of oxidation 5 stability and low temperature performance of said industrial lubricating fluid.

2. Use according to Claim 1, wherein the industrial lubricating fluid comprises at least 95wt% of base oil.

3. Use according to Claim 1 or Claim 2, wherein at least a 10 portion and up to 100wt% of the base oil is re-refined base oil.

4. Use according to any one of Claims 1 to 3, wherein the re-refined base oil is selected from one or both of Group I and Group II according to the API base oil categories. 15 5. Use according to Claim 4, wherein the re-refined base oil is a Group I base oil with a viscosity index of at least 95, a sulphur content of no more than 0.3% and a saturates content of at least 90%.

6. Use according to any one of Claims 1 to 5, the re- 20 refined base oil is base oil that has been recycled from used lubricant fluid using solvent extraction or hydrotreatment.

7. Use according to any one of Claims 1 to 6, wherein the overall amount of additives in the industrial lubricating 25 fluid is less than 5wt%, more preferably less than 3wt%, even more preferably less than 2wt% based on the overall weight of the industrial lubricating fluid.