Use of rerefined base oil

Abstract

The present invention provides the use of a rerefined base oil in an industrial lubricating fluid comprising at least one base oil and at least one additive to improve one or more of oxidative stability and low temperature performance of the industrial lubricating fluid.

Description

Technical Field

[0001] The present invention relates to the use of re-refined base oils in industrial lubricant formulations. Background Art

[0002] Lubricating fluids are required in all industrial equipment having moving parts. Thus, industrial lubricating fluids include hydraulic oils, gear oils, compressor oils, circulating oils, turbine oils, and the like. Such industrial lubricating fluids typically contain one or more base oils and one or more additives. Typically, the additive treatment rate for industrial lubricating fluids is significantly lower than that for engine oils, where an additive treatment rate of less than 5 wt% is common.

[0003] For such low additive treatment rates, the base oils used are crucial. Typically, so-called "virgin" base oils are used in the manufacture of industrial lubricating fluids. These are typically produced directly from crude oil or natural gas by refining or by synthetic methods.

[0004] The disposal of used lubricating fluids requires careful handling, and the waste streams are typically used as burner fuel. In all technical fields, it is necessary to consider the carbon footprint of the product and to try and ensure that raw materials are reused and recycled where possible. This has led to the development of so-called "re-refined base oils". A re-refined base oil (RRBO) is a base oil derived from the reprocessing of used lubricating oil to remove contaminants, oxidation products, and additives.

[0005] Techniques such as distillation, thermal deasphalting, or solvent (usually propane) deasphalting are used as recycling techniques for used lubricating fluids. The intermediate products produced by the recycling techniques are unrefined and typically not suitable as lubricants without further improvement. Finishing techniques such as clay treatment, hydrotreating (see, for example, EP3921390A1, US11034895B1) or solvent extraction (as described in CN107574012A) can then be used to "finish" the quality of the intermediate into a salable base oil. When the recycling techniques and the finishing techniques are combined, they are generally referred to as re-refining techniques. Additional pretreatment steps can also be used to remove sludge, water, and additive metals before recycling occurs.

[0006] Previously, re-refined base oils were considered to be inferior in quality to virgin base oils. However, with the development of improved re-refining techniques, this is no longer the case. However, the focus on re-refining techniques and the re-refined base oils produced therefrom has been on producing and using base oils of sufficient quality such that they can pass the standards set for lubricating oils in industrial techniques (see, for example, CN104673460A and CN104673461A). The intention of the present inventors is to develop improved lubricating oils using RRBO. Summary of the Invention

[0007] Accordingly, the present invention provides the use of a re-refined base oil in an industrial lubricating fluid, the industrial lubricating fluid comprising at least one base oil and at least one additive, to improve one or more of the oxidation stability and low temperature performance of the industrial lubricating fluid. Detailed Embodiments

[0008] One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed technology. Additionally, for the sake of providing a concise description of these embodiments, not all features of actual specific implementations may be described in the specification.

[0009] When introducing elements of the various embodiments of the present disclosure, the articles "a", "an", and "the" are intended to mean that there is 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 in addition to the listed elements. Additionally, it should be understood that a reference to "an embodiment" or "embodiment" of the present disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0010] The inventors have surprisingly found that a re-refined base oil can be used to provide an improved fluid for use as an industrial lubricating fluid.

[0011] Industrial lubricating fluids include, but are not limited to, those used as hydraulic oils, gear oils, compressor oils, circulating oils, and turbine oils. The industrial lubricating fluid according to the present invention comprises at least one base oil and at least one additive.

[0012] The industrial lubricating fluid preferably comprises at least 95% by weight of base oil. According to the present invention, at least a portion and up to 100% by weight of the base oil is a re-refined base oil. Preferably, at least 10% by weight of the base oil in the industrial lubricating fluid is a re-refined base oil. Depending on the viscosity grade of the industrial lubricating fluid, for light grade industrial lubricating fluids, the RRBO treatment rate can be as high as almost 100%, while for heavy grade industrial lubricating fluids, a heavy virgin base oil may be required to bridge the viscosity gap.

[0013] The base oil that is not a re-refined base oil in the industrial lubricating fluid can be any suitable base oil commonly used in lubricating fluids. Specific examples include base oils of Classes I to IV belonging to the API (American Petroleum Institute - see Table 1) base oil categories, which can be used alone or in mixtures.

[0014] Table 1 - API Base Oil Categories

[0015]

[0016] Based on the API base oil category, the re-refined base oil used in the present invention is preferably of type I or type II. More preferably, the re-refined base oil used in the present invention is type I according to the API base oil category. Typical re-refined type I base oils, although belonging to the API classification of type I base oils, have characteristics that are not typical for the original type I base oils. Preferably, the saturate content of the type I re-refined base oil is preferably at least 80%, more preferably at least 90%. The viscosity index of the type I re-refined base oil is preferably at least 95, and more preferably at least 105. The sulfur content of the type I re-refined base oil preferably does not exceed 0.3%, and more preferably does not exceed 0.1%. The sulfur content of the type I re-refined base oil is greater than 0.03%, which is consistent with the API classification.

[0017] The re-refined base oil used in the present invention is preferably a base oil recycled from used lubricant fluids using solvent extraction or hydrotreating.

[0018] Preferably, based on the total weight of the industrial lubricating fluid, the total amount of additives in the industrial lubricating fluid is less than 5% by weight, more preferably less than 3% by weight, and even more preferably less than 2% by weight. Suitably, based on the total weight of the industrial lubricating fluid, the total amount of additives in the industrial lubricating fluid is at least 0.1% by weight. The additives can be incorporated into the industrial lubricating fluid individually or as part of one or more additive packages. Whether added individually or in the form of an additive package, the diluent oil can be included with the additives and form part of the finished industrial lubricating fluid.

[0019] Depending on the end use of the industrial lubricating fluid, different types of additives will be suitable. These include but are not limited to anti-wear additives, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, antioxidants, rust and corrosion inhibitors, dispersants, demulsifiers, and foam inhibitors.

[0020] Anti-wear additives and extreme pressure additives include phosphorus compounds such as phosphates, acidic phosphates, amine salts of acidic phosphates, basic phosphates, phosphites, thiophosphates, zinc dialkyldithiophosphates, esters of dialkyldithiophosphoric acid with alkanols or polyether-type alcohols and their derivatives, phosphorus-containing carboxylic acids, and phosphorus-containing carboxylic acid esters.

[0021] As examples of viscosity index improvers, non-dispersant viscosity index improvers such as polymethacrylates and olefin polymers such as ethylene-propylene copolymers, styrene-diene copolymers, polyisobutene, and polystyrene, and dispersant viscosity index improvers in which nitrogen-containing monomers have been copolymerized with these, and they can be prepared from types different from copolymers of olefins and alkyl methacrylates can be mentioned.

[0022] As examples of pour point depressants, polymers based on polymethacrylates can be mentioned.

[0023] Suitable antioxidants include amine-based antioxidants, sulfur-based antioxidants, phenol-based antioxidants, and phosphorus-based antioxidants. These antioxidants can be used alone or in combination.

[0024] As examples of demulsifiers suitable for use in the industrial lubricating fluids according to the present invention, mention may be made of those demulsifiers that are commonly used as additives in lubricating oils in the known art. In order to impart anti-foaming properties to the lubricating oil compositions of the present invention, anti-foaming agents may also be added.

[0025] As examples of anti-foaming agents suitable for use in the industrial lubricating fluids according to the present invention, mention may be made of organosilicic acid esters such as dimethylpolysiloxane, diethyl silicate, and fluorosiloxanes, as well as non-siloxane type anti-foaming agents such as alkyl polyacrylates.

[0026] The present invention will now be illustrated by the following non-limiting examples.

[0027] Example

[0028] As shown in Tables 3 to 6, a series of industrial lubricant formulations were blended and tested. The following base oils (having the properties listed in Table 2) were used in the examples.

[0029] Group I 150SN and 500SN are commercially available from Hindustan Petroleum Corporation Limited (HPCL) under the trade names Alprol N32 and Alprol N100.

[0030] Group II 150N and 500N are commercially available from Hainan Handi Sunshine Petrochemical Co. under the trade names HDS-150N and HDS-500N.

[0031] Group I RRBO 150SN is commercially available from Hebei Jingu Recycling Resources Development Co. under the trade name JINGU 150SN.

[0032] Group II RRBO 150N is commercially available from Changzhou FINAS Energy Technology Co. under the trade name FINAS150N.

[0033] Table 2

[0034]

[0035] The hydraulic oil packages used in the formulations are standard industrial hydraulic oil additive packages that are commercially available.

[0036] The pour point depressant used in the formulation is a standard commercially available pour point depressant.

[0037] The defoaming additive used in the formulation is a commercially available defoaming additive.

[0038] As can be seen from Tables 3 to 6, Class I or Class II RRBO-based samples show performance advantages over their virgin base oil counterparts, such as higher VI, lower viscosity at 0 °C, and better oxidation stability as reflected by the RPVOT and TOST test results.

[0039] Table 3

[0040]

[0041] Table 4

[0042]

[0043] Table 5

[0044]

[0045] Table 6

[0046]

Claims

1. Use of a re-refined base oil in an industrial lubricating fluid, the industrial lubricating fluid comprising at least one base oil and at least one additive, to improve one or more of the oxidation stability and low temperature properties of the industrial lubricating fluid.

2. The use according to claim 1, wherein the industrial lubricating fluid comprises at least 95% by weight of base oil.

3. The use according to claim 1 or claim 2, wherein at least a portion and up to 100% by weight of the base oil is a re-refined base oil.

4. The 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 API base oil categories.

5. The use according to claim 4, wherein the re-refined base oil is a Group I base oil having a viscosity index of at least 95, a sulfur content of not more than 0.3%, and a saturates content of at least 90%.

6. The use according to any one of claims 1 to 5, wherein the re-refined base oil is a base oil that has been recycled from a used lubricant fluid using solvent extraction or hydrotreating.

7. The use according to any one of claims 1 to 6, wherein based on the total weight of the industrial lubricating fluid, the total amount of additives in the industrial lubricating fluid is less than 5% by weight, more preferably less than 3% by weight, and even more preferably less than 2% by weight.

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