USE OF RE-REFINED BASE OIL

Description

FIELD OF THE INVENTION

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 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, the additive treat rate for industrial lubricating fluids is considerably lower than for engine oils, with additive treat rates of less than 5 wt % being usual.

With such a low additive treat rate, the base oil being used is of key importance. Typically, so called ‘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 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 “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 technologies are unfinished and typically unsuited for use as lubricants without further improvement. Finishing technologies such as clay treatment, hydrotreatment (see, for example, EP3921390A1, U.S. Ser. No. 11/034,895B1), or solvent extraction (as described in CN107574012A may then be used 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 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 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 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, 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 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 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. 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.

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, 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 comprises at least 95 wt % of base oil. According to the invention, of this base oil, at least a portion and up to 100 wt % is re-refined base oil. Preferably at least 10 wt % 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 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 (American Petroleum Institute—see Table 1) base oil categories, which can be used alone or in a mixture.

The re-refined base oil used in the present 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 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 preferably at least 95 and more preferably at least 105. 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 lubricant fluid using solvent extraction or hydrotreatment.

Preferably the overall amount of additives in the industrial lubricating fluid is less than 5 wt %, more preferably less than 3 wt %, even more preferably less than 2 wt % based on the overall weight of the industrial lubricating fluid. Suitably, the overall amount of additives in the industrial lubricating fluid is at least 0.1 wt % based on the overall weight of the industrial lubricating fluid. The additives may be incorporated into 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.

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-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 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 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 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 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, 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.

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 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.

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, 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.